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Article

Nutrients, Phytochemicals, and Antioxidant Capacity of Red Raspberry Nectar Fermented with Lacticaseibacillus paracasei

by
Feng Shi
1,†,
Yin Qin
1,2,†,
Shuyi Qiu
1 and
You Luo
1,3,*
1
School of Liquor and Food Engineering, Guizhou University, Guiyang 550025, China
2
School of Food and Drug Manufacturing Engineering, Guizhou Institute of Technology, Guiyang 550003, China
3
Centre for Nutrition and Food Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, QLD 4068, Australia
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Foods 2024, 13(22), 3666; https://doi.org/10.3390/foods13223666
Submission received: 5 October 2024 / Revised: 9 November 2024 / Accepted: 14 November 2024 / Published: 18 November 2024
(This article belongs to the Section Food Microbiology)
Browse Figures
Versions Notes

Abstract

:
Fresh raspberries are highly perishable, but lactic acid bacteria fermentation offers a favourable method for developing healthy products. This study investigated the effects of Lacticaseibacillus paracasei fermentation on the nutrients and phytochemicals of red raspberry nectar using widely targeted metabolomics, as well as its antioxidant activity. The fermentation notably disrupted the raspberry tissue structure, reshaped its non-volatile composition, and increased its DPPH and hydroxyl free radical scavenging abilities. A total of 261 compounds showed significant differences, with 198 upregulated and 63 downregulated. Among these, certain flavonoid glucosides (e.g., pelargonid-in-3-O-rutinoside, delphinidin-3-O-rutinoside-7-O-glucoside, and kaempferol-3-O-glucoside) were significantly downregulated, while some bioactive phenolic acids (e.g., 3-(4-Hydroxyphenyl)-propionic acid and DL-3-phenyllactic acid), alkaloids (e.g., deoxymutaaspergillic acid and indole-3-lactic acid), amino acids (e.g., L-phenylalanine and L-glutamine), and B vitamins (e.g., VB6, VB7, and VB3) were substantially upregulated. Furthermore, the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation and enrichment analysis revealed that metabolic pathways and the biosynthesis of secondary metabolites contributed significantly to the new profile of fermented red raspberry nectar. These findings provide valuable insights for developing fermented raspberry products using Lacticaseibacillus paracasei, which can help minimise fresh raspberry loss and enhance their valorisation.

1. Introduction

Rubus idaeus (red raspberry) is a highly nutritious fruit that provides a rich source of dietary fibre, vitamins, and phenolic compounds [1]. A growing body of studies have shown that red raspberries have positive effects on human health and wellness, such as anti-cancer [2] and anti-diabetic activity [3,4]. However, fresh red raspberries have an extremely short shelf life due to their delicate tissue structure and high respiration rate [5,6]. Freezing and frozen storage are popular methods for prolonging their quality and shelf life, while fermentation is a safer, more sustainable, and preferred strategy for preserving fresh foods and creating new delicious and healthy products [7].
Probiotic fermentation is a traditional and favourable processing method that can greatly enhance the flavour, nutritional profile, and health benefits of foods [7,8]. Lactobacillus species are considered safe starter cultures and probiotics which are widely used in the manufacture of fermented foods such as yogurt, cheese, and kimchi. Numerous studies have verified that lactobacilli are appropriate strains for fruit processing and contribute to nutrient availability and flavour enhancement, as well as health benefits [9,10,11,12,13]. For example, Xu et al. reported that four lactobacilli, including Levilactobacillus brevis, Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, and Limosilactobacillus fermentum, improved the total flavonoid and phenolic levels, vitamin C content, and antioxidant capacity of Citrus juice [13]. Wen et al. indicated that Lacticaseibacillus casei fermentation increased the polyphenol, flavone, and exopolysaccharide levels in litchi juice, thereby enhancing its immunomodulatory effects and gut-microbiota-regulating activity [9].
Several studies have examined how Saccharomyces or non-Saccharomyces yeast fermentation affects the volatile [14,15] and non-volatile compounds [16,17,18] in red raspberry juice. However, no research has yet explored the impact of pure fermentation with a single Lactobacillus strain on the non-volatile composition of red raspberry nectar. Our previous work showed that Lacticaseibacillus paracasei FBKL 1.0328 (Lc. paracasei FBKL 1.0328) significantly transformed phytochemicals in Rosa roxburghii Tratt juice and enhanced its antioxidant activity [19]. Therefore, this study aimed to comprehensively investigate the impact of Lc. paracasei FBKL 1.0328 fermentation on the nutrients, and phytochemicals of red raspberry nectar using widely targeted metabolomics, as well as its antioxidant capacity. The findings underscore the beneficial effects of Lc. paracasei FBKL 1.0328 fermentation on red raspberry nectar, including the enhanced antioxidant capacity and elevated levels of certain bioactive phenolic acids and nutrients, providing a valuable reference for the development of novel functional red raspberry products.

2. Materials and Methods

2.1. Samples and Chemicals

Fresh red raspberries were purchased from a Walmart in Guiyang, Guizhou, China. Their place of origin was Menghai County, Xishuangbanna, Yunan, China. Lacticaseibacillus paracasei FBKL 1.0328 was isolated from a local fermented food Suantang and kept at the Fermentation Engineering Laboratory of Guizhou University.
Acetonitrile, methanol, and formic acid (chromatographic grade) were provided by Merck (Darmstadt, Germany). DPPH was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). Other chemicals were obtained from Sinopharm Chemical Reagent Co., Ltd. (Beijing, China).

2.2. Fermentation of Red Raspberry Nectar

The average weight of each red raspberry fruit is approximately four grams. Fresh red raspberries (172.63 g) were mixed with distilled water (340 mL), then pressed and filtered through 80-mesh nylon cloth to obtain raspberry nectar. Raspberry nectar (30 mL per tube) was transferred to 50 mL centrifuge tubes and sterilised at 121 °C for 15 min in a high-pressure steam steriliser (Shenan, Shanghai, China).
Lc. paracasei FBKL 1.0328 was activated with fresh MRS (de Man, Rogosa, and Sharpe) broth. The stock culture (1 mL) was added to 100 mL of MRS broth (Bio-way, Shanghai, China) and incubated at 37 °C for 24 h. The bacterial cells were then obtained by centrifugation (4500× g, 10 min, 4 °C), washed twice with sterile water, and resuspended in sterile phosphate-buffered saline (PBS) to be used as the inoculum for the red raspberry nectar.
The red raspberry nectar without inoculation was used as the control and labeled UFR. The fermentation group (FR) was inoculated with 7.21 Log CFU/mL of activated Lc. paracasei FBKL 1.0328. All samples were incubated statically in a 37 °C anaerobic incubator (Hengzi, Shanghai, China) for 48 h. After fermentation, samples were centrifuged (LICHEN, Shanghai, China) at 4 °C for 10 min (6580× g). The supernatants were stored at −80 °C for analysis, while the residues were freeze-dried for scanning electron microscopy (SEM) analysis.

2.3. Determination of Viable Cells

Viable cell counts were determined by the agar serial dilution method. The fermented red raspberry nectar (1 mL) was diluted with normal saline, and 100 μL of each dilution was plated on MRS agar. Samples were cultured at 37 °C for 48 h. The Petri dishes containing 30–300 colonies were counted and recorded as log CFU/mL [19].

2.4. Scanning Electron Microscope of UFR and FR Residues

A small amount of sample (unfermented/fermented nectar sediments) was adhered to a conductive adhesive and coated with gold/palladium alloy by the Oxford Quorum SC7620 sputter coating (Laughton, UK). The morphology of sample was collected by a ZEISS GeminiSEM 300 scanning electron microscope (Oberkochen, Germany) in secondary electron imaging mode.

2.5. Determination of Physicochemical Parameters of UFR and FR

The L (lightness), a (green/red), and b (blue/yellow) of samples were measured by a Chroma meter CR-400 (KONICA MINOLTA, Tokyo, Japan). The Brix (total soluble solids) of samples was measured with a handheld refractometer at 25 °C (VWR, Radnor, PA, USA). The total sugar and reducing sugar content of samples were measured by the phenol-sulfuric acid method [20] and the 3,5-dinitrosalicylic acid method [21], respectively. The pH values of samples were measured with a pH meter (PHS-2F, INESA, Shanghai, China). The total acidity was determined by titration with 0.1 mol/L of NaOH (National Standard of the people’s Republic of China, GB-12456-2021) [22]. Tartaric acid served as the reference acid for titration.

2.6. Determination of Total Phenolic and Total Flavonoid Content

The total phenolic content and total flavonoid content of the unfermented and fermented samples were determined by Folin–Ciocalteu and AlCl3 colorimetric method, respectively. The procedures followed those outlined in a previous study [19].

2.7. Identification of Non-Volatile Compounds

The non-volatile compounds of samples were detected and identified using an ultra-high-performance liquid chromatography–triple quadrupole mass spectrometry system, according to a method described by Li et al. [23]. Thawed samples were vortexed for 10 s. Subsequently, each sample (100 μL) was mixed with 100 μL of 70% methanol containing the internal standard (2-Chloro-L-phenylalanine, 1 ppm). After agitation for 15 min, samples were centrifuged at 4 °C for 3 min (14,800× g), and the supernatants were analysed by UHPLC (ExionLCTM AD, Framingham, MA, USA) coupled with MS/MS (QTRAP 4500, SCIEX, Framingham, MA, USA).
The UHPLC conditions were as follows: column—Agilent SB-C18 (2.1 × 100 mm, 1.8 μm; Santa Clara, CA, USA), mobile phases—purified water containing 0.1% formic acid (A) and acetonitrile containing 0.1% (v/v) formic acid (B), flow rate—0.35 mL/min, injection volume—2 μL, column temperature—40 °C, and the elution gradient—0 min, 5% B; 0–9 min, 5–95% B; 9–10 min, 95% B; 10.00–11.10 min, 5% B; and 11.10–14 min, 5% B. The mass spectrometer was run in negative (−4500 V)/positive (5500 V) ionisation mode over a scan range of 100–1250 Da with the following settings: electrospray ionisation source temperature, 550 °C; ion source gas I, 50 psi; gas II, 60 psi; curtain gas, 25 psi; the collision-induced ionisation, high; the collision gas (nitrogen), medium; and the triple quadrupole mass spectrometer scan mode, Multiple Reaction Monitoring (MRM). Quality control (QC) samples were regularly tested to ensure method and instrument performance.
Compound identification was performed using MS/MS data, internal standards, the MS/MS library, and the Metware Database. Isotope signals, redundant signals containing K+, Na+, and NH4+ ions, and fragment ion signals from larger molecules were excluded during analysis. Compound quantification was achieved using the MRM mode on a triple quadrupole mass spectrometer. The precursor ion of the target compound was selected to minimise interferences, then fragmented in the collision cell to generate product ions. The triple quadrupole filtered these to select a specific characteristic fragment ion. After obtaining mass spectrometry data, peak area integration was performed for all chromatographic peaks, and the peak areas for the same metabolite across different samples were corrected and integrated.

2.8. Evaluation of In Vitro Antioxidant Activity

The antioxidant activity of samples was evaluated by DPPH, ABTS, and OH radical scavenging assays [24,25], as well as the reducing power test [26].

2.9. Statistical Analysis

All tests were performed in triplicate, and results were expressed as mean ± standard deviation. Significant differences between UFR and FR were determined by the paired t-test using SPSS 22.0 (IBM), with p < 0.05 considered statistically significant. Compound data were processed using hierarchical cluster analysis (HCA), principal component analysis (PCA), and orthonormal partial least-squares discriminant analysis (OPLS-DA) with the R package Complex Heatmap, R function “prcomp”, and MetaboAnalystR, respectively. Identified compounds were annotated through the Kyoto Encyclopedia of Genes and Genomes (KEGG) compound database.

3. Results and Discussion

3.1. The Effects of Lc. paracasei Fermentation on Red Raspberry Tissue Structure

The surface morphology of unfermented and fermented red raspberry tissue is shown in Figure 1. The unfermented sample had a relatively smooth surface with numerous thin, intact laminae and a compact microstructure (Figure 1A,C), whereas the fermented sample exhibited a rough, fluffy surface with exposed filaments and scattered irregular fragments (Figure 1B,D). This evidence suggests that Lc. paracasei can considerably break down the structure of red raspberry tissue, facilitating the liberation and conversion of components. Similarly, Zhang et al. observed cracks and small fragments on the outer wall of bee pollen after fermentation [27]. The degradation of plant cell walls is driven by various enzymes, such as cellulase and pectinase, which enhances the bio-accessibility and bioavailability of nutrients and bioactive compounds in substrates [10,16,28].

3.2. The Viability of Lc. paracasei FBKL 1.0328 in Red Raspberry Nectar

As shown in Table 1, the viable cells of Lc. paracasei increased significantly from 7.21 log CFU/mL to 9.84 log CFU/mL after 48 h of fermentation (p < 0.05), indicating its ability to grow and proliferate in the red raspberry nectar without additional nutrients. This suggests Lc. paracasei is a promising strain for developing new raspberry products. Likewise, three LAB strains-L. plantarum NCU116, L. acidophilus NCU402, and L. casei NCU215-achieved robust growth in blueberry juice, reaching 8.0 log CFU/mL after 24 h of fermentation [12].

3.3. The Basic Physicochemical Properties of UFR and FR

Lc. paracasei fermentation resulted in a significant decrease in the L* value, a slight increase in the a* value, and a slight decrease in the b* value of red raspberry nectar, indicating reduced lightness and yellowness, but a redder hue (Table 1). The colour of the juice or nectar correlates with the pH and anthocyanin composition. Fermentation causes fluctuations in the pH and alters the anthocyanin levels, leading to changes in colour [12].
The total soluble solids of red raspberry nectar significantly dropped from 6.10 to 5.83 after fermentation. The total sugar content mildly decreased from 463.38 to 458.59 μg/mL, while the reducing sugar content slightly increased from 278.62 to 297.63 μg/mL (Table 1). This may be attributed to the hydrolysis of polysaccharides or glycosylated compounds. Sugars released from these complex compounds can partially compensate the consumed monosaccharides and disaccharides [29,30,31]. In addition to carbohydrates, Lc. paracasei can utilise other components to survive and thrive, such as protein, lipid, and organic acid. The variation in the sugar content during the LAB fermentation of fruits varied from case to case. For example, LAB fermentation significantly reduced the total soluble solids and glucose in blueberry juice [12]. A notable decline occurred in the sucrose concentration of a vegetable–fruit beverage after fermentation, while its total sugar content showed no significant change [32]. The total sugar content in the sea buckthorn juice was not significantly affected by the fermentation process, because the employed L. plantarum preferentially utilised organic acids instead of sugars as the carbon source [33]. The total acidity of red raspberry nectar notably increased from 9.92 to 12.24 g/L after fermentation. Correspondingly, the pH significantly decreased from 3.25 to 3.12 (Table 1). In general, LAB converts the sugars in substrates into organic acids, leading to a rise in the total acidity and a drop in the sugar content.

3.4. The Total Phenolic and Flavonoid Content of UFR and FR

Microbial fermentation can release and transform phenolics, thereby affecting their levels in foods. The total phenolic content and total flavonoid content in UFR were 346.39 μg GAE/mL and 482.28 μg RE/mL, respectively, while the total phenolic content and total flavonoid content in FR were 336.50 μg GAE/mL and 446.84 μg RE/mL, respectively (Table 1). Lc. paracasei fermentation did not significantly change the total phenolic content of red raspberry nectar but remarkably reduced its flavonoid content by 7.35%. Studies show that LAB fermentation either increased or decreased the total phenolic and flavonoid content of substrates. Some research indicates that LAB can boost the levels of phenolics and flavonoids [19,34,35]. Conversely, some studies report reductions in the total phenolic and flavonoid content after fermentation [11,36]. For example, Adebo et al. observed decreased flavonoid, phenolic, and tannin levels in ting (a Southern African food) fermented with Lacticaseibacillus strains [36]. Li et al. found a significant increase in the total phenolic content but a considerable decrease in the total flavonoid content of jujube juice after LAB fermentation [10]. These variations highlight that the effects of LAB fermentation on the polyphenolic concentration depends on the specific strains and substrates.

3.5. Overview of the Non-Volatile Composition Profile of UFR and FR

The non-volatile compounds in the unfermented and fermented red raspberry nectar were analysed qualitatively and quantitatively using UHPLC-MS/MS in the MRM model. The total ion current (TIC) chromatogram is shown in Supplementary Figure S1. The high overlap between samples and QC samples indicated the reproducibility, stability, and reliability of the data. Furthermore, the proportion of substances with coefficient of variation (CV) values below 0.3 in QC samples exceeded 85% (shown in Supplementary Figure S2), indicating that the experimental data were highly stable.
A total of 1729 compounds were identified, which consisted of amino acids and their derivatives (20.53%, n = 355), phenolic acids (12.20%, n = 211), flavonoids (11.05%, n = 191), alkaloids (9.66%, n = 167), terpenoids (8.27%, n = 143), lignans and coumarins (6.13%, n = 106), lipids (5.73%, n = 99), organic acids (5.67%, n = 98), nucleotides and their derivatives (3.7%, n = 64), tannins (0.93%, n = 16), quinones (0.58%, n = 10), steroids (0.12%, n = 2), and others (15.44%, n = 267). A heatmap (Figure 2) visualises the relative content of these components, showing the distinct clustering of FR and UFR. Most compounds in FR, especially amino acids, their derivatives, and alkaloids, were significantly upregulated, highlighted in red. This coincided with previous findings where most amino acids and their derivatives and alkaloids in Rosa roxburghii Tratt juice were considerably upregulated after Lc. paracasei fermentation [19].

3.6. The Differences in Primary Nutrients and Phytochemicals Between UFR and FR

Lc. paracasei fermentation remarkably transformed the chemical composition of red raspberry nectar. PCA analysis (Figure 3A) displayed a clear separation between FR and UFR, which was further confirmed by an OPLS-DA analysis (Figure 3B). A total of 261 compounds showed significant differences, with 198 upregulated and 63 downregulated (Figure 3C). This was consistent with some previous studies, in which lactic acid bacteria impacted the non-volatile and volatile compounds of fruit juice or nectar considerably [12,19,37].
The significantly differential compounds (n = 261) were classified into 11 categories, including amino acids and their derivatives (n = 113), alkaloids (n = 34), nucleotides and their derivatives (n = 20), flavonoids (n = 20), phenolic acids (n = 16), organic acids (n = 17), lipids (n = 10), terpenoids (n = 8), lignans and coumarins (n = 5), tannins (n = 1), and others (n = 17). Amino acids and their derivatives, phenolic compounds, and alkaloids were the predominant differential metabolites. The top 50 differential compounds between FR and UFR shown in Table 2 were screened by Variable Importance in Projection (VIP), VIP > 1, and Fold Change (FC), FC ≥ 2 or FC ≤ 0.5, based on the OPLS-DA model. Moreover, violin plots (Figure 3D) illustrate the relative content and distribution of the top 20 differential compounds between the FR and UFR group. Except for nicotinamide, all other compounds were remarkably upregulated in FR. The most prominently upregulated compounds, which were phenolic acids with a high abundance, include 3-(4-hydroxyphenyl)-propionic acid, DL-3-phenyllactic acid, 2-hydroxy-3-phenylpropanoic acid, and tropic acid. Additionally, amino acids and their derivatives were substantially upregulated, including Asp-Phe-Arg, Gly-Gly-Gln, Cyclo (L-prolyl-L-tyrosine), Cyclo(L-tyrosyl-D-proline), Cyclo(D-Val-L-Pro), Cyclo(L-Phe-trans-4-hydroxy-L-Pro), and N-(1-deoxy-1-fructosyl) phenylalanine.

3.6.1. Amino Acids and Their Derivatives

A total of 113 amino acids and their derivatives were identified as differential metabolites between FR and UFR, with 100 upregulated and 13 downregulated. These compounds were mainly short peptides, cyclic peptides, and amino acid derivatives, which impact sensory quality and biological activities. For instance, N-(1-deoxy-1-fructosyl)leucine, a sweet amino acid derivative [38], increased by 16.12 times after fermentation. Essential amino acids such as L-phenylalanine (5.04-fold increase), DL-methionine (3.09-fold increase), and L-glutamine (2.62-fold increase) could influence the taste of raspberry nectar. Generally, glutamine provides a sweet taste, while phenylalanine, methionine, tryptophan, lysine, and isoleucine contribute bitterness. In addition, some upregulated cyclodipeptides, such as cyclo(Pro-Val), cyclo(Pro-Leu), and cyclo(L-Pro-L-Tyr), have shown antibacterial activity [39]. Different strains produce distinct amino acid profiles. The co-fermentation with Lacticaseibacillus rhamnosus and Gluconacetobacter xylinus reduced the content of bitter and sweet free amino acids in yacon–litchi–longan juice [40]. W. anomalus fermentation significantly decreased the bitter leucine content in black garlic juice [41].

3.6.2. Organic Acids

Organic acids lower the pH of the fermenting “must” to a level where many spoilage bacteria cannot survive. On the other hand, they play an important role in the taste and flavour of fermented foods. Lc. paracasei fermentation modified the organic acid profile of red raspberry nectar, with 17 organic acids (14 upregulated and 3 downregulated) showing significant differences between FR and UFR. Notably, the L-lactic acid content substantially increased by 13.29 times due to the conversion of carbohydrates and malic acid during fermentation. Fumaric acid, L-malic acid, and D-malic acid were downregulated, leading to the reduced tartness of red raspberry nectar [42,43], while lactic acid and malic acid in Goji berry juice were significantly elevated after fermentation with Tibetan kefir grains containing lactic acid bacteria, acetic acid bacteria, and yeasts [44]. Additionally, the concentration of L-tartaric acid and oxalic acid in FR increased significantly by 15.80 and 13.07 times, respectively. Similar results were observed in Limosilactobacillus reuteri fermented apple juice [42]. But Zhao et al. found that LAB greatly decreased the tartaric acid and oxalic acid content in jujube–wolfberry juice [45]. These findings indicate that the strain-specific metabolism and substrates together create the organic acid profile of a product.

3.6.3. Nucleotides and Their Derivatives

The fermentation significantly changed 20 nucleotides and their derivatives in red raspberry nectar, with 15 upregulated (such as 2′-deoxyadenosine, inosine, and thymine) and 5 downregulated (such as 5′-deoxy-5′-(methylthio)adenosine, 6-O-methylguanine, and 2-deoxy-D-ribose). Similar results were observed in the LAB fermentation of Rosa roxburghii Tratt juice [19], wolfberry–longan juice [35], and barley extracts [46], as well as E. cristatum fermentation of dark tea [47]. For instance, LAB increased the 5′-guanylic acid content in wolfberry–longan juice but decreased several purine metabolites like adenosine and guanosine [35]. Additionally, Lc. paracasei fermentation significantly upregulated 2′-deoxyadenosine, 2′-deoxyguanosine, and 2′-deoxyinosine in Rosa roxburghii Tratt juice [19].

3.6.4. Lipids

Raspberries contain a lot of tiny hard seeds which are a great source of high-quality oil. Approximately, 10–25% of the oil can be recovered [48]. Lc. paracasei fermentation significantly changed the content of 10 lipids (3 up-regulated and 7 down-regulated) in red raspberry nectar. Three free fatty acids, namely, punicic acid (polyunsaturated fatty acid, 19.10-fold increase), octadeca-9,12,15-trienoic acid (polyunsaturated fatty acid, 8.95-fold increase), and undecylic acid (saturated fatty acid, 6.96-fold increase), were significantly upregulated. Similarly, Filannino et al. reported that the levels of mono, di-, and tri-hydroxy-octadecenoic acids in avocado nectar were enhanced by L. plantarum AVEF17 fermentation [49]. Interestingly, punicic acid is an “omega-5” polyunsaturated fatty acid originally found in pomegranate seed oil. To the best of our knowledge, this is the first report of its identification in red raspberry seed oil. Punicic acid is recognised as a functional substance with potential efficacy against various chronic diseases, as demonstrated in vitro and in animal models [50].

3.6.5. Vitamins

Fruits are a rich source of vitamins, but they have relatively low levels of vitamin B and K [43]. It has been reported that lactic acid bacteria fermentation not only provides an acidic environment that maintain the stability of vitamins but also can synthesise water-soluble vitamins such as vitamin B [51]. Lc. paracasei fermentation significantly increased the concentrations of pyridoxine (VB6), biotin (VB7), and nicotinic acid (VB3) in red raspberry nectar, with elevations of 6.78, 4.99, and 2.82 times, respectively, whereas another form of VB3-nicotinamide in red raspberry nectar was remarkably downregulated after fermentation. This indicates that Lc. paracasei is a vitamin-B-producing strain and could be used to develop novel vitamin-B-enriched products. Similarly, Kaprasob et al. found that four lactic acid bacteria strains (Lactobacillus acidophilus, Lacticaseibacillus casei, Lactiplantibacillus plantarum, and Leuconostoc mesenteroides) boosted the levels of B-group vitamins (B1, B2, B3, B6, and B12) in cashew apple juice [52].

3.6.6. Alkaloids

Lc. paracasei fermentation significantly increased the levels of 31 alkaloids in red raspberry nectar. Key examples included deoxymutaaspergillic acid (59.64-fold increase), N-benzoyl-2-aminoethyl-β-D-glucopyranoside (27.27-fold increase), and tryptamine (16.75-fold increase). Only three alkaloids (including N, N-cinnamoylbutanediamine, oxoassoanine N-oxide, and α-hydroxyquinoline) were significantly reduced. Some up-regulated alkaloids have been scientifically proven to possess specific pharmacological properties. For example, deoxymutaaspergillic acid was shown to be moderately active against MCF-7 (a breast cancer cell line) and weakly active against HepG2 cell line [53]. Indole-3-lactic acid plays a key role in anti-inflammation [54,55]. Additionally, 5-methoxy-3-indole acetic acid can activate hepatic Nrf2 and stimulate the transcription of genes involved in the cellular antioxidant response, thereby protecting the liver from acetaminophen overdose and acute ethanol toxicity [56]. These suggest that Lc. paracasei fermentation can greatly enhance certain beneficial alkaloids. Similar results were observed with other lactic acid bacteria [19,57].

3.6.7. Phenolic Compounds

Lc. paracasei fermentation greatly transformed phenolic acids (13 upregulated and 4 downregulated) and flavonoids (7 upregulated and 13 downregulated) in red raspberry nectar. Some desirable phenolic acids were remarkably upregulated after fermentation. 3-(4-Hydroxyphenyl)-propionic acid (103.59-fold increase), a metabolite of procyanidin A2, has the potential to inhibit cellular oxidative stress and inflammation [58]. DL-3-phenyllactic acid (58.35-fold increase) has been proven as an ideal antimicrobial compound with broad and potent antimicrobial activity against both fungi and bacteria [59,60,61,62]. It can be converted from phenyl pyruvic acid by certain lactic acid bacteria under the action of lactic dehydrogenase [63,64]. Hydroxytyrosol (10.73-fold increase) is considered one of most powerful natural antioxidants [65], and has other beneficial effects on physic health, such as anti-inflammatory and anti-tumour activity [66,67]. Mandelic acid (2.32-fold increase) has effective anti-microbial properties [68]. Similarly, Zhao et al. reported that LAB significantly elevated the levels of certain phenolic acids (such as gallic acid, chlorogenic acid, and caffeic acid) in jujube–wolfberry composite juice and thereby improved its antioxidant capacity [45].
Most individual flavonoids in red raspberry nectar were significantly downregulated after fermentation, especially flavonoid glucosides, such as pelargonidin-3-O-rutinoside, delphinidin-3-O-rutinoside-7-O-glucoside, and kaempferol-3-O-glucoside. Montijo-Prieto et al. also observed that L. plantarum 748T resulted in a considerable decrease in aryl-glucosides such as quercetin-3-glucoside isomer b, protocatechuic acid 4-glucoside, luteolin-7-O-(2″-O-pentosyl)-hexoside isomer d, and kaempferol-O-hexoside isomer b. Likewise, Wu et al. found that the levels of cyanindin-3-glucoside and peonidin-3-glucoside in blueberry and blackberry juice dropped significantly after fermentation with L. plantarum, Streptococcus thermophilus, and Bifidobacterium [31,69]. Additionally, Qin et al. reported a progressive decrease in anthocyanins, identified as glycosides of cyanidin, pelargonidin, and delphinidin, in red raspberry juice during fermentation [18]. This might be attributed to microbial glycosidases, which hydrolyse flavonoid glucosides [70,71]. Conversely, some flavonoid glucosides were significantly upregulated, such as delphinidin-3-O-arabinoside, apigenin-4′-O-glucoside, and apigenin-7-O-glucoside. Similarly, Montijo-Prieto et al. reported that the concentrations of flavonoid glucosides such as luteolin-7-O-(2″-O-pentosyl)-hexoside isomer a, quercetin-diglucoside, and quercetin-3-O-arabinosyl-glucoside in avocado leaves were enhanced after fermentation [69].

3.6.8. Terpenoids

Terpenoids are a diverse class of secondary metabolites including monoterpenoids, sesquiterpenoids, diterpenoids, triterterpenoids, tetraterpenoids, and polyterpenoids [72]. A total of eight terpenoids in red raspberry nectar were considerably affected by Lc. paracasei. The level of glucosyl 7-methyl-3-methyleneoctane-1,2,6,7-tetraol (monoterpenoid), shanzhiside (monoterpenoid), and ailantinol D (diterpenoid) significantly increased, while the content of 3,4-dihydroverbenalin (monoterpenoid), suavissimoside R1 (triterpene saponin), 3-hydroxy-23-oxoolean-12-en-28-oic acid (triterpene), caesalpin J (sesquiterpenoid), and (8R)-9-hydroxy-8-(hydroxymethyl)-6-methoxy-8-methylpyrano [2,3-f]chromen-2-one (terpene) in red raspberry nectar was markedly reduced after fermentation. The fermentation tended to upregulate some monoterpenoids and downregulate some higher-order terpenoids, such as triterpene and sesquiterpenoids in red raspberry nectar. This indicates that high-molecular-weight terpenoids were decomposed by Lc. paracasei into low-molecular-weight ones. Mandha et al. reported that most sesquiterpenes in mango juice decreased, while the total monoterpenes content remained unchanged after LAB fermentation [73].

3.7. KEGG Annotation and Enrichment Analysis of Differential Compounds

Most differential compounds between FR and UFR were annotated to metabolic pathways (44 compounds) and the biosynthesis of secondary metabolites (19 compounds), as shown in Figure 4A. Furthermore, the KEGG enrichment analysis revealed that the most significantly enriched pathways were nucleotide metabolism, purine metabolism, and ABC transporters during the Lc. paracasei fermentation of red raspberry nectar (Figure 4B). Organic acids, amino acids, nucleotides, and their derivatives are the primary differential compounds enriched in these pathways. These results provide insights into the metabolic functions of Lc. paracasei and the differential compounds associated with specific pathways. However, further investigation is needed to elucidate the biotransformation mechanism, including the examination of gene expression and enzyme activity.
Similarly, the significantly enriched pathways involved in the formation of LAB-fermented Rosa roxburghii Tratt juice were ABC transporters, nucleotide metabolism, purine metabolism, and metabolic pathways [19], while the significantly enriched KEGG pathways involved in the LAB fermentation of wolfberry–longan juice were related to amino acid metabolism [35]. These metabolic differences are attributed to both the strain species and the substrates used.

3.8. The In Vitro Antioxidant Activity of UFR and FR

Lc. paracasei fermentation significantly improved the DPPH and hydroxyl radical scavenging abilities of red raspberry nectar by 7.26% and 6.87%, respectively, while the ABTS radical scavenging ability remained unchanged. However, its reducing power significantly decreased by 7.19% (Table 1). Similarly, LAB fermentation notably improved the DPPH and ABTS radical scavenging abilities of Opuntia ficus-indica fruit juice but did not have an impact on its ferric reducing antioxidant power [74]. In contrast, W. anomalus fermentation reduced the DPPH and ABTS radical scavenging abilities of black garlic juice by 5.2% and 1.4%, respectively [41]. Based on these cases, it can be concluded that fermentation affects the antioxidant capacity of substrates, influencing both the radical scavenging ability and reducing capacity, with outcomes that can be either positive or negative. The antioxidant activity is correlated with the type and content of antioxidants present. In fermentation systems, both the antioxidants originally present in the substrates and those produced by the microbes can influence the overall antioxidant capacity. Leonard et al. indicated that an enhancement in the antioxidant capacity correlates with the augmented presence of phenolic acids and other antioxidants during microbial hydrolysis reactions and metabolism [75]. Given that this study only examined two groups, it is not possible to establish direct and reliable correlations between specific antioxidants and the antioxidant capacity. Future research involving a broader range of groups helps to identify key antioxidants and their contributions to antioxidant activity.

4. Conclusions

Lc. paracasei FBKL 1.0328 fermentation significantly modified the nutrients and phytochemicals of red raspberry nectar, resulting in 261 significant differential compounds (198 upregulated and 63 downregulated). Amino acids and derivatives (n = 113), phenolic compounds (n = 37), and alkaloids (n = 34) were the three largest groups of differential components between the unfermented red raspberry nectar and the fermented one. Certain desirable nutrients (e.g., essential amino acids, lactic acid, and vitamin B) and bioactive compounds (e.g., 3-(4-hydroxyphenyl)-propionic acid, DL-3-phenyllactic acid, and ndole-3-lactic acid) were notably upregulated. Simultaneously, the fermentation significantly enhanced the DPPH and OH radical scavenging abilities of red raspberry nectar. Furthermore, the KEGG enrichment analysis uncovered that nucleotide metabolism, purine metabolism, and ABC transporters contributed significantly to the new non-volatile composition profile of fermented red raspberry nectar. These findings provide a sound reference for the development of fermented red raspberry products.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/foods13223666/s1, Figure S1:The total ion current (TIC) of samples including quality control (QC); Figure S2: Coefficient of Variation (CV) distribution diagram of each group of samples.

Author Contributions

F.S.: investigation, formal analysis, validation, and writing—original draft; Y.Q.: formal analysis, writing—original draft, and funding acquisition; S.Q.: resources; Y.L.: conceptualisation, data curation, writing—review and editing, funding acquisition, supervision, and project administration. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Guizhou Provincial Research Program (Natural Science) (ZK [2022]086, [2019]2381), the Guizhou University Talent Research Fund ([2021]-26 and [2023]-29), the China Scholarship Fund (Liujinxuan [2023]40), and the Youth Science and Technology Talent Development Project of Colleges and Universities of Guizhou Province (Talent Base of Fermentation Engineering and Liquor Making in Guizhou Province [2018]3).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author.

Acknowledgments

We sincerely thank Zhang Jiale (UQ) for his assistance with the SEM analysis and Li Ming (UQ) for providing us with expert advice on UHPLC-MS/MS data analysis.

Conflicts of Interest

The authors declare that there are no conflicts of interest.

References

  1. Sadik, H.; Ouazzani, C.; Moustaghfir, A.; El Ghammarti, S.; Er-Ramly, A.; Essebbahi, I.; Dami, A.; Balouch, L. Comparison of the nutritional proprieties of commercial strawberries, red and black raspberry consumed in Morocco. Appl. Food Res. 2023, 3, 100362. [Google Scholar] [CrossRef]
  2. God, J.; Tate, P.L.; Larcom, L.L. Red raspberries have antioxidant effects that play a minor role in the killing of stomach and colon cancer cells. Nutr. Res. 2010, 30, 777–782. [Google Scholar] [CrossRef] [PubMed]
  3. Derrick, S.A.; Kristo, A.S.; Reaves, S.K.; Sikalidis, A.K. Effects of Dietary Red Raspberry Consumption on Pre-Diabetes and Type 2 Diabetes Mellitus Parameters. Int. J. Environ. Res. Public Health 2021, 18, 9364. [Google Scholar] [CrossRef] [PubMed]
  4. Uclés, R.M.; González-Sarrías, A.; Espín, J.C.; Tomás-Barberán, F.A.; Janes, M.; Cheng, H.; Finley, J.; Greenway, F.; Losso, J.N. Effects of red raspberry polyphenols and metabolites on the biomarkers of inflammation and insulin resistance in type 2 diabetes: A pilot study. Food Funct. 2022, 13, 5166–5176. [Google Scholar] [CrossRef] [PubMed]
  5. Shi, K.; Liu, Z.; Wang, J.; Zhu, S.; Huang, D. Nitric oxide modulates sugar metabolism and maintains the quality of red raspberry during storage. Sci. Hortic. 2019, 256, 108611. [Google Scholar] [CrossRef]
  6. Huynh, N.K.; Wilson, M.D.; Stanley, R.A. Extending the shelf life of raspberries in commercial settings by modified atmosphere/modified humidity packaging. Food Packag. Shelf Life 2023, 37, 101069. [Google Scholar] [CrossRef]
  7. Jahn, L.J.; Rekdal, V.M.; Sommer, M.O.A. Microbial foods for improving human and planetary health. Cell 2023, 186, 469–478. [Google Scholar] [CrossRef]
  8. Mukherjee, A.; Breselge, S.; Dimidi, E.; Marco, M.L.; Cotter, P.D. Fermented foods and gastrointestinal health: Underlying mechanisms. Nat. Rev. Gastroenterol. Hepatol. 2024, 21, 248–266. [Google Scholar] [CrossRef]
  9. Wen, J.; Ma, L.; Xu, Y.; Wu, J.; Yu, Y.; Peng, J.; Tang, D.; Zou, B.; Li, L. Effects of probiotic litchi juice on immunomodulatory function and gut microbiota in mice. Food Res. Int. 2020, 137, 109433. [Google Scholar] [CrossRef]
  10. Li, T.; Jiang, T.; Liu, N.; Wu, C.; Xu, H.; Lei, H. Biotransformation of phenolic profiles and improvement of antioxidant capacities in jujube juice by select lactic acid bacteria. Food Chem. 2021, 339, 127859. [Google Scholar] [CrossRef]
  11. Isas, A.S.; Escobar, F.; Álvarez-Villamil, E.; Molina, V.; Mateos, R.; Lizarraga, E.; Mozzi, F.; Van Nieuwenhove, C. Fermentation of pomegranate juice by lactic acid bacteria and its biological effect on mice fed a high-fat diet. Food Biosci. 2023, 53, 102516. [Google Scholar] [CrossRef]
  12. He, Y.; Hu, M.; He, W.; Li, Y.; Liu, S.; Hu, X.; Nie, S.; Yin, J.; Xie, M. Volatile compound dynamics during blueberry fermentation by lactic acid bacteria and its potential associations with bacterial metabolism. Food Biosci. 2024, 59, 103639. [Google Scholar] [CrossRef]
  13. Xu, H.; Feng, L.; Deng, Y.; Chen, L.; Li, Y.; Lin, L.; Liang, M.; Jia, X.; Wang, F.; Zhang, X.; et al. Change of phytochemicals and bioactive substances in Lactobacillus fermented Citrus juice during the fermentation process. LWT 2023, 180, 114715. [Google Scholar] [CrossRef]
  14. González, E.A.; Agrasar, A.T.; Castro, L.M.P.; Fernández, I.O.; Guerra, N.P. Solid-state fermentation of red raspberry (Rubus ideaus L.) and arbutus berry (Arbutus unedo, L.) and characterization of their distillates. Food Res. Int. 2011, 44, 1419–1426. [Google Scholar] [CrossRef]
  15. Jiang, Y.; Luo, T.; Tang, Y.; Chen, S.; Ni, H.; Chen, Q.; Song, X.; Bao, Y.; Deng, Z.; Wang, J. Isolation of a novel characterized Issatchenkia terricola from red raspberry fruits on the degradation of citric acid and enrichment of flavonoid and volatile profiles in fermented red raspberry juice. Food Sci. Hum. Wellness 2022, 11, 1018–1027. [Google Scholar] [CrossRef]
  16. Liang, T.; Jiang, T.; Liang, Z.; Zhang, N.; Dong, B.; Wu, Q.; Gu, B. Carbohydrate-active enzyme profiles of Lactiplantibacillus plantarum strain 84-3 contribute to flavor formation in fermented dairy and vegetable products. Food Chem. X 2023, 20, 101036. [Google Scholar] [CrossRef]
  17. Yuan, Y.; Tian, Y.; Gao, S.; Zhang, X.; Gao, X.; He, J. Effects of environmental factors and fermentation on red raspberry anthocyanins stability. LWT 2023, 173, 114252. [Google Scholar] [CrossRef]
  18. Qin, Y.; Luo, Y.; Qiu, S.; Zhang, Q.; Yang, L. Secondary metabolite profiles and bioactivities of red raspberry juice during fermentation with Wickerhamomyces anomalus. LWT 2024, 191, 115706. [Google Scholar] [CrossRef]
  19. Luo, Y.; Tang, R.; Qiu, H.; Song, A. Widely targeted metabolomics-based analysis of the impact of L. plantarum and L. paracasei fermentation on rosa roxburghii Tratt juice. Int. J. Food Microbiol. 2024, 417, 110686. [Google Scholar] [CrossRef]
  20. Sun, X.; Yan, Z.; Zhu, T.; Zhu, J.; Wang, Y.; Li, B.; Meng, X. Effects on the color, taste, and anthocyanins stability of blueberry wine by different contents of mannoprotein. Food Chem. 2019, 279, 63–69. [Google Scholar] [CrossRef]
  21. Wood, I.P.; Elliston, A.; Ryden, P.; Bancroft, I.; Roberts, I.N.; Waldron, K.W. Rapid quantification of reducing sugars in biomass hydrolysates: Improving the speed and precision of the dinitrosalicylic acid assay. Biomass Bioenergy 2012, 44, 117–121. [Google Scholar] [CrossRef]
  22. GB 12456-2021; National Food Safety Standard-Determination of Total Acidity in Food. National Health Commission of the People’s Republic of China: Beijing, China, 2021.
  23. Li, W.; Wen, L.; Chen, Z.; Zhang, Z.; Pang, X.; Deng, Z.; Liu, T.; Guo, Y. Study on metabolic variation in whole grains of four proso millet varieties reveals metabolites important for antioxidant properties and quality traits. Food Chem. 2021, 357, 129791. [Google Scholar] [CrossRef] [PubMed]
  24. Luo, Y.; Peng, B.; Liu, Y.; Wu, Y.; Wu, Z. Ultrasound extraction of polysaccharides from guava leaves and their antioxidant and antiglycation activity. Process Biochem. 2018, 73, 228–234. [Google Scholar] [CrossRef]
  25. Zhou, S.; Huang, G.; Chen, G. Extraction, structural analysis, derivatization and antioxidant activity of polysaccharide from Chinese yam. Food Chem. 2021, 361, 130089. [Google Scholar] [CrossRef]
  26. Canabady-Rochelle, L.L.S.; Harscoat-Schiavo, C.; Kessler, V.; Aymes, A.; Fournier, F.; Girardet, J.-M. Determination of reducing power and metal chelating ability of antioxidant peptides: Revisited methods. Food Chem. 2015, 183, 129–135. [Google Scholar] [CrossRef]
  27. Zhang, H.; Lu, Q.; Liu, R. Widely targeted metabolomics analysis reveals the effect of fermentation on the chemical composition of bee pollen. Food Chem. 2022, 375, 131908. [Google Scholar] [CrossRef]
  28. Matthews, A.; Grimaldi, A.; Walker, M.; Bartowsky, E.; Grbin, P.; Jiranek, V. Lactic Acid Bacteria as a Potential Source of Enzymes for Use in Vinification. Appl. Environ. Microbiol. 2004, 70, 5715–5731. [Google Scholar] [CrossRef]
  29. Mahajan, P.M.; Desai, K.M.; Lele, S.S. Production of Cell Membrane-Bound α- and β-Glucosidase by Lactobacillus acidophilus. Food Bioprocess Technol. 2012, 5, 706–718. [Google Scholar] [CrossRef]
  30. Iliev, I.; Vasileva, T.; Bivolarski, V.; Momchilova, A.; Ivanova, I. Metabolic Profiling of Xylooligosaccharides by Lactobacilli. Polymers 2020, 12, 2387. [Google Scholar] [CrossRef]
  31. Wu, B.; Liu, J.; Yang, W.; Zhang, Q.; Yang, Z.; Liu, H.; Lv, Z.; Zhang, C.; Jiao, Z. Nutritional and flavor properties of grape juice as affected by fermentation with lactic acid bacteria. Int. J. Food Prop. 2021, 24, 906–922. [Google Scholar] [CrossRef]
  32. Yang, X.; Zhou, J.; Fan, L.; Qin, Z.; Chen, Q.; Zhao, L. Antioxidant properties of a vegetable–fruit beverage fermented with two Lactobacillus plantarum strains. Food Sci.Biotechnol. 2018, 27, 1719–1726. [Google Scholar] [CrossRef] [PubMed]
  33. Markkinen, N.; Laaksonen, O.; Nahku, R.; Kuldjärv, R.; Yang, B. Impact of lactic acid fermentation on acids, sugars, and phenolic compounds in black chokeberry and sea buckthorn juices. Food Chem. 2019, 286, 204–215. [Google Scholar] [CrossRef] [PubMed]
  34. Ricci, A.; Cirlini, M.; Maoloni, A.; Del Rio, D.; Calani, L.; Bernini, V.; Galaverna, G.; Neviani, E.; Lazzi, C. Use of Dairy and Plant-Derived Lactobacilli as Starters for Cherry Juice Fermentation. Nutrients 2019, 11, 213. [Google Scholar] [CrossRef]
  35. Zheng, Z.; Wei, L.; Zhu, M.; Qian, Z.; Liu, J.; Zhang, L.; Xu, Y. Effect of lactic acid bacteria co-fermentation on antioxidant activity and metabolomic profiles of a juice made from wolfberry and longan. Food Res. Int. 2023, 174, 113547. [Google Scholar] [CrossRef]
  36. Adebo, O.A.; Njobeh, P.B.; Adebiyi, J.A.; Kayitesi, E. Co-influence of fermentation time and temperature on physicochemical properties, bioactive components and microstructure of ting (a Southern African food) from whole grain sorghum. Food Biosci. 2018, 25, 118–127. [Google Scholar] [CrossRef]
  37. Laophongphit, A.; Wichiansri, S.; Siripornadulsil, S.; Siripornadulsil, W. Enhancing the nutritional value and functional properties of mango nectar via lactic acid bacteria fermentation. LWT 2024, 197, 115878. [Google Scholar] [CrossRef]
  38. Azi, F.; Tu, C.; Meng, L.; Zhiyu, L.; Cherinet, M.T.; Ahmadullah, Z.; Dong, M. Metabolite dynamics and phytochemistry of a soy whey-based beverage bio-transformed by water kefir consortium. Food Chem. 2021, 342, 128225. [Google Scholar] [CrossRef]
  39. Castaldi, S.; Cimmino, A.; Masi, M.; Evidente, A. Bacterial Lipodepsipeptides and Some of Their Derivatives and Cyclic Dipeptides as Potential Agents for Biocontrol of Pathogenic Bacteria and Fungi of Agrarian Plants. J. Agric. Food Chem. 2022, 70, 4591–4598. [Google Scholar] [CrossRef]
  40. Chen, H.; Xiao, G.; Xu, Y.; Yu, Y.; Wu, J.; Zou, B. High Hydrostatic Pressure and Co-Fermentation by Lactobacillus rhamnosus and Gluconacetobacter xylinus Improve Flavor of Yacon-Litchi-Longan Juice. Foods 2019, 8, 308. [Google Scholar] [CrossRef]
  41. Huang, Y.-B.; Meng, F.-B.; Gong, C.-X.; Deng, Y.; Li, Y.-C.; Jiang, L.-S.; Zhong, Y. Widely targeted metabolomics and flavoromics reveal the effect of Wickerhamomyces anomalus fermentation on the volatile and nonvolatile metabolites of black garlic juice. Food Chem. 2024, 460, 140534. [Google Scholar] [CrossRef]
  42. Ji, G.; Liu, G.; Li, B.; Tan, H.; Zheng, R.; Sun, X.; He, F. Influence on the aroma substances and functional ingredients of apple juice by lactic acid bacteria fermentation. Food Biosci. 2023, 51, 102337. [Google Scholar] [CrossRef]
  43. Yang, X.; Hong, J.; Wang, L.; Cai, C.; Mo, H.; Wang, J.; Fang, X.; Liao, Z. Effect of Lactic Acid Bacteria Fermentation on Plant-Based Products. Fermentation 2024, 10, 48. [Google Scholar] [CrossRef]
  44. Du, G.; Qing, Y.; Wang, H.; Wang, N.; Yue, T.; Yuan, Y. Effects of Tibetan kefir grain fermentation on the physicochemical properties, phenolics, enzyme activity, and antioxidant activity of Lycium barbarum (Goji berry) juice. Food Biosci. 2023, 53, 102555. [Google Scholar] [CrossRef]
  45. Zhao, X.; Tang, F.; Cai, W.; Peng, B.; Zhang, P.; Shan, C. Effect of fermentation by lactic acid bacteria on the phenolic composition, antioxidant activity, and flavor substances of jujube–wolfberry composite juice. LWT 2023, 184, 114884. [Google Scholar] [CrossRef]
  46. Zhao, Y.; Wu, C.; Zhu, Y.; Zhou, C.; Xiong, Z.; Eweys, A.S.; Zhou, H.; Dong, Y.; Xiao, X. Metabolomics strategy for revealing the components in fermented barley extracts with Lactobacillus plantarum dy-1. Food Res. Int. 2021, 139, 109808. [Google Scholar] [CrossRef]
  47. Xiao, Y.; He, C.; Chen, Y.; Ho, C.-T.; Wu, X.; Huang, Y.; Gao, Y.; Hou, A.; Li, Z.; Wang, Y.; et al. UPLC–QQQ–MS/MS-based widely targeted metabolomic analysis reveals the effect of solid-state fermentation with Eurotium cristatum on the dynamic changes in the metabolite profile of dark tea. Food Chem. 2022, 378, 131999. [Google Scholar] [CrossRef]
  48. Grajzer, M.; Wiatrak, B.; Gębarowski, T.; Boba, A.; Rój, E.; Gorczyca, D.; Prescha, A. Bioactive Compounds of Raspberry Oil Emulsions Induced Oxidative Stress via Stimulating the Accumulation of Reactive Oxygen Species and NO in Cancer Cells. Oxidative Med. Cell. Longev. 2021, 2021, 5561672. [Google Scholar] [CrossRef]
  49. Filannino, P.; Tlais, A.Z.A.; Morozova, K.; Cavoski, I.; Scampicchio, M.; Gobbetti, M.; Di Cagno, R. Lactic acid fermentation enriches the profile of biogenic fatty acid derivatives of avocado fruit (Persea americana Mill.). Food Chem. 2020, 317, 126384. [Google Scholar] [CrossRef]
  50. Shabbir, M.A.; Khan, M.R.; Saeed, M.; Pasha, I.; Khalil, A.A.; Siraj, N. Punicic acid: A striking health substance to combat metabolic syndromes in humans. Lipids Health Dis. 2017, 16, 99. [Google Scholar] [CrossRef]
  51. LeBlanc, J.G.; Laiño, J.E.; del Valle, M.J.; Vannini, V.; van Sinderen, D.; Taranto, M.P.; de Valdez, G.F.; de Giori, G.S.; Sesma, F. B-Group vitamin production by lactic acid bacteria—Current knowledge and potential applications. J. Appl. Microbiol. 2011, 111, 1297–1309. [Google Scholar] [CrossRef]
  52. Kaprasob, R.; Kerdchoechuen, O.; Laohakunjit, N.; Somboonpanyakul, P. B vitamins and prebiotic fructooligosaccharides of cashew apple fermented with probiotic strains Lactobacillus spp., Leuconostoc mesenteroides and Bifidobacterium longum. Process Biochem. 2018, 70, 9–19. [Google Scholar] [CrossRef]
  53. Shaala, L.; Youssef, D.; Badr, J.; Harakeh, S. Bioactive 2(1H)-Pyrazinones and Diketopiperazine Alkaloids from a Tunicate-Derived Actinomycete Streptomyces sp. Molecules 2016, 21, 1116. [Google Scholar] [CrossRef] [PubMed]
  54. Meng, D.; Sommella, E.; Salviati, E.; Campiglia, P.; Ganguli, K.; Djebali, K.; Zhu, W.; Walker, W.A. Indole-3-lactic acid, a metabolite of tryptophan, secreted by Bifidobacterium longum subspecies infantis is anti-inflammatory in the immature intestine. Pediatr. Res. 2020, 88, 209–217. [Google Scholar] [CrossRef] [PubMed]
  55. Yu, K.; Li, Q.; Sun, X.; Peng, X.; Tang, Q.; Chu, H.; Zhou, L.; Wang, B.; Zhou, Z.; Deng, X.; et al. Bacterial indole-3-lactic acid affects epithelium–macrophage crosstalk to regulate intestinal homeostasis. Proc. Natl. Acad. Sci. USA 2023, 120, e2309032120. [Google Scholar] [CrossRef] [PubMed]
  56. Saeedi, B.J.; Liu, K.H.; Owens, J.A.; Hunter-Chang, S.; Camacho, M.C.; Eboka, R.U.; Chandrasekharan, B.; Baker, N.F.; Darby, T.M.; Robinson, B.S.; et al. Gut-Resident Lactobacilli Activate Hepatic Nrf2 and Protect Against Oxidative Liver Injury. Cell Metab. 2020, 31, 956–968.e5. [Google Scholar] [CrossRef]
  57. Xie, H.; Gao, P.; Lu, Z.-M.; Wang, F.-Z.; Chai, L.-J.; Shi, J.-S.; Zhang, H.-L.; Geng, Y.; Zhang, X.-J.; Xu, Z.-H. Changes in physicochemical characteristics and metabolites in the fermentation of goji juice by Lactiplantibacillus plantarum. Food Biosci. 2023, 54, 102881. [Google Scholar] [CrossRef]
  58. Zhang, Y.-Y.; Li, X.-L.; Li, T.-Y.; Li, M.-Y.; Huang, R.-M.; Li, W.; Yang, R.-L. 3-(4-Hydroxyphenyl)propionic acid, a major microbial metabolite of procyanidin A2, shows similar suppression of macrophage foam cell formation as its parent molecule. RSC Adv. 2018, 8, 6242–6250. [Google Scholar] [CrossRef]
  59. Dieuleveux, V.; Lemarinier, S.; Guéguen, M. Antimicrobial spectrum and target site of d-3-phenyllactic acid. Int. J. Food Microbiol. 1998, 40, 177–183. [Google Scholar] [CrossRef]
  60. Debonne, E.; Vermeulen, A.; Bouboutiefski, N.; Ruyssen, T.; Van Bockstaele, F.; Eeckhout, M.; Devlieghere, F. Modelling and validation of the antifungal activity of DL-3-phenyllactic acid and acetic acid on bread spoilage moulds. Food Microbiol. 2020, 88, 103407. [Google Scholar] [CrossRef]
  61. Ning, Y.; Fu, Y.; Hou, L.; Ma, M.; Wang, Z.; Li, X.; Jia, Y. iTRAQ-based quantitative proteomic analysis of synergistic antibacterial mechanism of phenyllactic acid and lactic acid against Bacillus cereus. Food Res. Int. 2021, 139, 109562. [Google Scholar] [CrossRef]
  62. Jiang, Y.-H.; Ying, J.-P.; Xin, W.-G.; Yang, L.-Y.; Li, X.-Z.; Zhang, Q.-L. Antibacterial activity and action target of phenyllactic acid against Staphylococcus aureus and its application in skim milk and cheese. J. Dairy Sci. 2022, 105, 9463–9475. [Google Scholar] [CrossRef] [PubMed]
  63. Dieuleveux, V.; Guéguen, M. Antimicrobial Effects of d-3-Phenyllactic Acid on Listeria monocytogenes in TSB-YE Medium, Milk, and Cheese. J. Food Prot. 1998, 61, 1281–1285. [Google Scholar] [CrossRef] [PubMed]
  64. Zhang, X.; Zhang, S.; Shi, Y.; Shen, F.; Wang, H. A new high phenyl lactic acid-yielding Lactobacillus plantarum IMAU10124 and a comparative analysis of lactate dehydrogenase gene. FEMS Microbiol. Lett. 2014, 356, 89–96. [Google Scholar] [CrossRef]
  65. Martínez, L.; Ros, G.; Nieto, G. Hydroxytyrosol: Health Benefits and Use as Functional Ingredient in Meat. Medicines 2018, 5, 13. [Google Scholar] [CrossRef]
  66. Kourti, M.; Skaperda, Z.; Tekos, F.; Stathopoulos, P.; Koutra, C.; Skaltsounis, A.L.; Kouretas, D. The Bioactivity of a Hydroxytyrosol-Enriched Extract Originated after Direct Hydrolysis of Olive Leaves from Greek Cultivars. Molecules 2024, 29, 299. [Google Scholar] [CrossRef]
  67. Hormozi, M.; Marzijerani, A.S.; Baharvand, P. Effects of Hydroxytyrosol on Expression of Apoptotic Genes and Activity of Antioxidant Enzymes in LS180 Cells. Cancer Manag. Res. 2020, 12, 7913–7919. [Google Scholar] [CrossRef]
  68. Choińska, R.; Dąbrowska, K.; Świsłocka, R.; Lewandowski, W.; Świergiel, A.H. Antimicrobial Properties of Mandelic Acid, Gallic Acid and their Derivatives. Mini-Rev. Med. Chem. 2021, 21, 2544–2550. [Google Scholar] [CrossRef]
  69. De Montijo-Prieto, S.; Razola-Díaz, M.D.C.; Barbieri, F.; Tabanelli, G.; Gardini, F.; Jiménez-Valera, M.; Ruiz-Bravo, A.; Verardo, V.; Gómez-Caravaca, A.M. Impact of Lactic Acid Bacteria Fermentation on Phenolic Compounds and Antioxidant Activity of Avocado Leaf Extracts. Antioxidants 2023, 12, 298. [Google Scholar] [CrossRef]
  70. Michlmayr, H.; Kneifel, W. β-Glucosidase activities of lactic acid bacteria: Mechanisms, impact on fermented food and human health. FEMS Microbiol. Lett. 2014, 352, 1–10. [Google Scholar] [CrossRef]
  71. Landete, J.M.; Curiel, J.A.; Rodríguez, H.; de las Rivas, B.; Muñoz, R. Aryl glycosidases from Lactobacillus plantarum increase antioxidant activity of phenolic compounds. J. Funct. Foods 2014, 7, 322–329. [Google Scholar] [CrossRef]
  72. Pichersky, E.; Raguso, R.A. Why do plants produce so many terpenoid compounds? New Phytol. 2018, 220, 692–702. [Google Scholar] [CrossRef] [PubMed]
  73. Mandha, J.; Shumoy, H.; Devaere, J.; Schouteten, J.J.; Gellynck, X.; De Winne, A.; Matemu, A.O.; Raes, K. Effect of Lactic Acid Fermentation on Volatile Compounds and Sensory Characteristics of Mango (Mangifera indica) Juices. Foods 2022, 11, 383. [Google Scholar] [CrossRef] [PubMed]
  74. Wang, H.; He, X.; Li, J.; Wu, J.; Jiang, S.; Xue, H.; Zhang, J.; Jha, R.; Wang, R. Lactic acid bacteria fermentation improves physicochemical properties, bioactivity, and metabolic profiles of Opuntia ficus-indica fruit juice. Food Chem. 2024, 453, 139646. [Google Scholar] [CrossRef] [PubMed]
  75. Leonard, W.; Zhang, P.; Ying, D.; Adhikari, B.; Fang, Z. Fermentation transforms the phenolic profiles and bioactivities of plant-based foods. Biotechnol. Adv. 2021, 49, 107763. [Google Scholar] [CrossRef] [PubMed]
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Figure 1. SEM morphology of UFR and FR tissue: UFR sample (A,C), and FR sample (B,D). UFR: unfermented red raspberry nectar, FR: fermented red raspberry nectar.
Figure 1. SEM morphology of UFR and FR tissue: UFR sample (A,C), and FR sample (B,D). UFR: unfermented red raspberry nectar, FR: fermented red raspberry nectar.
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Figure 2. Heatmap for identified chemical composition of FR and UFR. UFR: unfermented red raspberry nectar, FR: fermented red raspberry nectar (Note: The columns represent the two groups, and each row indicates a compound in all samples; a color-coded scale grading from red to green means the relative content of metabolites from high to low).
Figure 2. Heatmap for identified chemical composition of FR and UFR. UFR: unfermented red raspberry nectar, FR: fermented red raspberry nectar (Note: The columns represent the two groups, and each row indicates a compound in all samples; a color-coded scale grading from red to green means the relative content of metabolites from high to low).
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Foods 13 03666 g003aFoods 13 03666 g003b
Figure 3. (A) PCA plot of all identified compounds of FR and UFR; (B) OPLS-DA plot of FR and UFR; (C) volcano plot of all identified compounds of FR and UFR; and (D) the violin plots of raw intensity of the top 20 differential compounds between FR and UFR. UFR: unfermented red raspberry nectar, FR: fermented red raspberry nectar.
Figure 3. (A) PCA plot of all identified compounds of FR and UFR; (B) OPLS-DA plot of FR and UFR; (C) volcano plot of all identified compounds of FR and UFR; and (D) the violin plots of raw intensity of the top 20 differential compounds between FR and UFR. UFR: unfermented red raspberry nectar, FR: fermented red raspberry nectar.
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Figure 4. KEGG annotation and enrichment of the differential compounds: (A) KEGG classification for FR vs. UFR, and (B) KEGG enrichment map for FR vs. UFR. UFR: unfermented red raspberry nectar, FR: fermented red raspberry nectar.
Figure 4. KEGG annotation and enrichment of the differential compounds: (A) KEGG classification for FR vs. UFR, and (B) KEGG enrichment map for FR vs. UFR. UFR: unfermented red raspberry nectar, FR: fermented red raspberry nectar.
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Table 1. The effects of Lc. paracasei fermentation on the basic physicochemical parameters of red raspberry nectar.
Table 1. The effects of Lc. paracasei fermentation on the basic physicochemical parameters of red raspberry nectar.
UFRFR
Viable cells (Log CFU/mL)-9.84 ± 0.03 **
L*25.74 ± 0.5422.51 ± 0.43 *
a*36.83 ± 1.1738.27 ± 1.59
b*12.11 ± 1.7811.67 ± 1.89
Total soluble solids (%)6.10 ± 0.005.83 ± 0.07 *
Total sugar (μg/mL)463.38 ± 5.30458.49 ± 8.62
Reducing sugar (μg/mL)278.62 ± 2.27297.63 ± 9.18
pH3.25 ± 0.003.12 ± 0.00 **
Total acidity (g/L)9.92 ± 0.0012.24 ± 0.09 **
Total polyphenols (μg/mL)346.39 ± 4.14336.50 ± 7.24
Total flavonoids (μg/mL)482.28 ± 3.39446.84 ± 3.33 **
DPPH radical scavenging rate (%)64.69 ± 0.6069.37 ± 0.54 *
ABTS radical scavenging rate (%)93.17 ± 0.3993.09 ± 0.49
Hydroxyl radical scavenging rate (%)89.25 ± 1.0695.38 ± 1.13 *
Reducing power (%)86.34 ± 1.4080.13 ± 1.37 **
*: p < 0.05; **: p < 0.01; “-”: none; UFR: the unfermented red raspberry nectar; FR: the fermented red raspberry nectar.
Table 2. The top 50 differential metabolites between FR and UFR.
Table 2. The top 50 differential metabolites between FR and UFR.
CategoryCompoundsIonization ModelPrecursor Ions (Da)Product Ions (Da)FormulaVIPFCType
Amino acids and derivatives (20)Asp-Phe-Arg[M+H]+437.21156.08C19H28N6O61.51108.26up
Cyclo(L-Phe-trans-4-hydroxy-L-Pro)[M+H]+261.12120.08C14H16N2O31.4948.71up
N-(1-deoxy-1-fructosyl)phenylalanine[M-H]-326.12164.07C15H21NO71.5436.89up
Gly-Gly-Gln[M+H]+261.12136.07C9H16N4O51.5236.62up
Cyclo(L-tyrosyl-D-proline)[M+H]+261.12136.08C14H16N2O31.5333.71up
Cyclo (L-prolyl-L-tyrosine)[M+H]+261.12136.08C14H16N2O31.5332.12up
Cyclo(D-Val-L-Pro)[M+H]+197.1370.07C10H16N2O21.5430.74up
Gly-Val-Val[M+H]+274.18129.1C12H23N3O41.5423.75up
Pro-Asn-Leu[M+H]+343.270.07C15H26N4O51.4622.36up
Cyclo(Pro-Val)[M+H]+197.1372.08C10H16N2O21.5422.12up
Tyr-Pro-Lys[M+H]+407.23323.2C20H30N4O51.4821.70up
Pro-Gln-Val[M+H]+343.2155.09C15H26N4O51.4618.76up
N-(1-deoxy-1-fructosyl)leucine[M-H]-292.14130.09C12H23NO71.5416.12up
Cyclo(L-Ala-L-Pro)[M+H]+169.170.07C8H12N2O21.5415.34up
Gly-Leu-Val[M+H]+288.19143.12C13H25N3O41.5313.50up
L-alanyl-L-leucine[M+H]+203.1486.1C9H18N2O31.5413.26up
Ile-Glu-Val[M+H]+360.21229.12C16H29N3O61.5413.17up
L-seryl-L-isoleucine[M+H]+219.1360.04C9H18N2O41.4212.46up
Cyclo(Pro-Phe)[M+H]+245.13120.08C14H16N2O21.5212.14up
Ala-Ile-Asn[M+H]+317.18120.08C13H24N4O51.5411.89up
Phenolic acids (8)2-Hydroxy-3-phenylpropanoic acid[M-H]-165.06103.06C9H10O31.54257.27up
Tropic acid[M-H]-165.06103.06C9H10O31.54228.82up
3-(4-Hydroxyphenyl)-propionic acid[M-H]-165.06119.05C9H10O31.54103.59up
DL-3-phenyllactic acid[M-H]-165.06119.05C9H10O31.5458.35up
Methyl 2,4-dihydroxyphenylacetate[M-H]-181.05135.04C9H10O41.5453.85up
2-Hydroxy-3-(4-hydroxyphenyl)propanoic acid[M-H]-181.05135.04C9H10O41.5445.35up
4-Hydroxyphenyllactic acid[M-H]-181.05135.04C9H10O41.5445.13up
10-Hydroxymajoroside[M-H]-403.12241.07C17H24O111.5412.81up
Alkaloids (7)Deoxymutaaspergillic acid[M+H]+211.1470.06C11H18N2O21.5459.64up
N-benzoyl-2-aminoethyl-β-D-glucopyranoside[M+H]+328.13310.12C15H21NO71.5427.27up
Tryptamine[M+H]+161.11144.08C10H12N21.5316.75up
1,2-Dihydro-13-norgalanthamine[M+H]+276.16120.08C16H21NO31.5412.81up
(22R,25R)-16β-H-22a-N-spirosol-3β-ol-5-ene-3-O-rhamnosyl(1→2)[rhamnosyl(1→4)]glucoside[M+H]+868.5868.5C45H73NO151.5412.64up
N-feruloyltyramine 4′-glucoside[M+H]+476.2177.05C24H29NO91.5112.42up
2-(Acetylamino)-3-phenyl-2-propenoic acid[M+H]+206.08118.07C11H11NO31.5412.41up
Organic acids (6)2-Hydroxy-4-methylpentanoic acid[M-H]-131.0785.07C6H12O31.5461.26up
2-Hydroxyisocaproic acid[M-H]-131.0785.07C6H12O31.5454.26up
Muconic acid[M-H]-141.0259.01C6H6O41.5220.69up
L-Tartaric acid[M-H]-149.0187.01C4H6O61.5415.80up
L-Lactic acid[M-H]-89.0271.02C3H6O31.5313.29up
Oxalic acid[M-H]-88.9970.98C2H2O41.5313.07up
Nucleotides and derivatives (3)2′-Deoxyadenosine[M+H]+252.11136.06C10H13N5O31.51173.83up
Inosine[M+H]+269.09137.05C10H12N4O51.5412.33up
9-(Arabinosyl)hypoxanthine[M-H]-267.07135.03C10H12N4O51.5312.18up
Lignans and Coumarins (1)Dihydrosesamin[M+H]+357.13307.09C20H20O61.440.07down
Lipids (1)Punicic acid [M+H]+279.2395.09C18H30O21.4519.10up
Others (4)2,6-Dimethoxybenzaldehyde[M-H]-165.06119.05C9H10O31.5457.99up
3-Ethyl-7-hydroxyphthalide[M+H]+179.07119.05C10H10O31.4122.87up
2,3-Dihydroxypropanal[M-H]-89.0271.02C3H6O31.5312.48up
Nicotinamide[M+H]+123.0680.05C6H6N2O1.540.01down
VIP: Variable Importance in Projection; FC: Fold Change; FR: the fermented red raspberry nectar; UFR: the unfermented red raspberry nectar.
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Shi, F.; Qin, Y.; Qiu, S.; Luo, Y. Nutrients, Phytochemicals, and Antioxidant Capacity of Red Raspberry Nectar Fermented with Lacticaseibacillus paracasei. Foods 2024, 13, 3666. https://doi.org/10.3390/foods13223666

AMA Style

Shi F, Qin Y, Qiu S, Luo Y. Nutrients, Phytochemicals, and Antioxidant Capacity of Red Raspberry Nectar Fermented with Lacticaseibacillus paracasei. Foods. 2024; 13(22):3666. https://doi.org/10.3390/foods13223666

Chicago/Turabian Style

Shi, Feng, Yin Qin, Shuyi Qiu, and You Luo. 2024. "Nutrients, Phytochemicals, and Antioxidant Capacity of Red Raspberry Nectar Fermented with Lacticaseibacillus paracasei" Foods 13, no. 22: 3666. https://doi.org/10.3390/foods13223666

APA Style

Shi, F., Qin, Y., Qiu, S., & Luo, Y. (2024). Nutrients, Phytochemicals, and Antioxidant Capacity of Red Raspberry Nectar Fermented with Lacticaseibacillus paracasei. Foods, 13(22), 3666. https://doi.org/10.3390/foods13223666

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