Polymers

2022

Jump to: 2021, 2020

23 pages, 1790 KiB

Open AccessReview

The Impacts of Bio-Based and Synthetic Hydrogels on Soil Hydraulic Properties: A Review

by Toby A. Adjuik, Sue E. Nokes, Michael D. Montross and Ole Wendroth

Polymers 2022, 14(21), 4721; https://doi.org/10.3390/polym14214721 - 4 Nov 2022

Cited by 30 | Viewed by 6078

Abstract

Soil hydraulic properties are important for the movement and distribution of water in agricultural soils. The ability of plants to easily extract water from soil can be limited by the texture and structure of the soil, and types of soil amendments applied to [...] Read more.

Soil hydraulic properties are important for the movement and distribution of water in agricultural soils. The ability of plants to easily extract water from soil can be limited by the texture and structure of the soil, and types of soil amendments applied to the soil. Superabsorbent polymers (hydrogels) have been researched as potential soil amendments that could help improve soil hydraulic properties and make water more available to crops, especially in their critical growing stages. However, a lack of a comprehensive literature review on the impacts of hydrogels on soil hydraulic properties makes it difficult to recommend specific types of hydrogels that positively impact soil hydraulic properties. In addition, findings from previous research suggest contrasting effects of hydrogels on soil hydraulic properties. This review surveys the published literature from 2000 to 2020 and: (i) synthesizes the impacts of bio-based and synthetic hydrogels on soil hydraulic properties (i.e., water retention, soil hydraulic conductivity, soil water infiltration, and evaporation); (ii) critically discusses the link between the source of the bio-based and synthetic hydrogels and their impacts as soil amendments; and (iii) identifies potential research directions. Both synthetic and bio-based hydrogels increased water retention in soil compared to unamended soil with decreasing soil water pressure head. The application of bio-based and synthetic hydrogels both decreased saturated hydraulic conductivity, reduced infiltration, and decreased soil evaporation. Hybrid hydrogels (i.e., a blend of bio-based and synthetic backbone materials) may be needed to prolong the benefit of repeated water absorption in soil for the duration of the crop growing season. Full article

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20 pages, 781 KiB

Open AccessArticle

Taguchi Grey Relational Analysis for Multi-Response Optimization of Bacillus Bacteria Flocculation Recovery from Fermented Broth by Chitosan to Enhance Biocontrol Efficiency

by Selena Dmitrović, Ivana Pajčin, Nataša Lukić, Vanja Vlajkov, Mila Grahovac, Jovana Grahovac and Aleksandar Jokić

Polymers 2022, 14(16), 3282; https://doi.org/10.3390/polym14163282 - 12 Aug 2022

Cited by 11 | Viewed by 2127

Abstract

Degradation of environment is a challenge to crop production around the world. Biological control of various plant diseases using antagonistic bacteria is an encouraging alternative to traditionally used chemical control strategies. Chitosan as a well-known natural flocculation agent also exhibits antimicrobial activity. The [...] Read more.

Degradation of environment is a challenge to crop production around the world. Biological control of various plant diseases using antagonistic bacteria is an encouraging alternative to traditionally used chemical control strategies. Chitosan as a well-known natural flocculation agent also exhibits antimicrobial activity. The goal of this study was to investigate a dual nature of chitosan in flocculation of Bacillus sp. BioSol021 cultivation broth intended for biocontrol applications. Experiments were performed based on L₁₈ standard Taguchi orthogonal array design with five input parameters (chitosan type and dosage, pH value, rapid and slow mixing rates). In this study, the grey relational analysis was used to perform multi-objective optimization of the chosen responses, i.e., flocculation efficiency and four inhibition zone diameters against the selected phytopathogens. The results have indicated a great potential of a highly efficient method for removal of the Bacillus bacteria from the cultivation broth using chitosan. The good flocculation efficiency and high precipitate antimicrobial activity against the selected phytopathogens were achieved. It has been shown that multiple flocculation performance parameters were improved, resulting in slightly improved response values. Full article

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2021

Jump to: 2022, 2020

29 pages, 1998 KiB

Open AccessReview

Cyclodextrins in Polymer-Based Active Food Packaging: A Fresh Look at Nontoxic, Biodegradable, and Sustainable Technology Trends

by Friné Velázquez-Contreras, Camilo Zamora-Ledezma, Iván López-González, Luis Meseguer-Olmo, Estrella Núñez-Delicado and José Antonio Gabaldón

Polymers 2022, 14(1), 104; https://doi.org/10.3390/polym14010104 - 28 Dec 2021

Cited by 17 | Viewed by 4779

Abstract

Using cyclodextrins (CDs) in packaging technologies helps volatile or bioactive molecules improve their solubility, to guarantee the homogeneous distribution of the complexed molecules, protecting them from volatilization, oxidation, and temperature fluctuations when they are associated with polymeric matrices. This technology is also suitable [...] Read more.

Using cyclodextrins (CDs) in packaging technologies helps volatile or bioactive molecules improve their solubility, to guarantee the homogeneous distribution of the complexed molecules, protecting them from volatilization, oxidation, and temperature fluctuations when they are associated with polymeric matrices. This technology is also suitable for the controlled release of active substances and allows the exploration of their association with biodegradable polymer targeting to reduce the negative environmental impacts of food packaging. Here, we present a fresh look at the current status of and future prospects regarding the different strategies used to associate cyclodextrins and their derivatives with polymeric matrices to fabricate sustainable and biodegradable active food packaging (AFP). Particular attention is paid to the materials and the fabrication technologies available to date. In addition, the use of cutting-edge strategies, including the trend of nanotechnologies in active food packaging, is emphasized. Furthermore, a critical view on the risks to human health and the associated updated legislation is provided. Some of the more representative patents and commercial products that currently use AFP are also listed. Finally, the current and future research challenges which must be addressed are discussed. Full article

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17 pages, 2349 KiB

Open AccessArticle

Effect of PLA Active Packaging Containing Monoterpene-Cyclodextrin Complexes on Berries Preservation

by Friné Velázquez-Contreras, Nelsy García-Caldera, José Daniel Padilla de la Rosa, Domingo Martínez-Romero, Estrella Núñez-Delicado and José Antonio Gabaldón

Polymers 2021, 13(9), 1399; https://doi.org/10.3390/polym13091399 - 26 Apr 2021

Cited by 28 | Viewed by 3007

Abstract

Blackberries and raspberries are highly perishable and fragile products, which limits their shelf life. The effect of biodegradable active packaging of blackberries and raspberries containing 2.5% and 5.0% weight (wt%) of thymol or carvacrol complexed in β-cyclodextrins (β-CDs), successively added to poly (lactic [...] Read more.

Blackberries and raspberries are highly perishable and fragile products, which limits their shelf life. The effect of biodegradable active packaging of blackberries and raspberries containing 2.5% and 5.0% weight (wt%) of thymol or carvacrol complexed in β-cyclodextrins (β-CDs), successively added to poly (lactic acid) (PLA), and melt-processed by injection molding was evaluated under stored conditions at 4 °C for 21 days, using as reference commercial clamshell and PLA package control samples. Thus, physicochemical, headspace, microbiological, and sensory quality studies were carried out in order to compare the efficacy of the different packages. Concerning weight loss, color, and total phenolic and soluble solids content, significant differences were detected when compared with commercial clamshell packaging. The results show that the PLA packages containing thymol and carvacrol complexes maintained the color, weight, and phenolic content of berries until day 21, with a score up to 45% better compared to commercial clamshell. The headspace analysis detected 101 mg L⁻¹ (ppm) of thymol and 35 ppm of carvacrol on the first day of refrigeration; these concentrations decreased with time. This release mechanism of carvacrol and thymol into the PLA package modified the initial atmosphere composition. After 21 days of storage, the berries had 4.25 degrees of acceptance, without adverse perception of aroma or flavor for both carvacrol and thymol compounds. A general microbial inhibition was observed for yeast and molds, which increased with the concentration of monoterpene in PLA packages, and showed an inhibition of 3.5 log units for PLA packages containing thymol, and of 3 log units for those containing carvacrol. Overall results show that PLA/β-CD-thymol 5.0% packages prolonged raspberries’ and blackberries’ shelf life by one more week at 4 °C, compared with commercial clamshell packaging. Full article

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23 pages, 9590 KiB

Open AccessArticle

Rheological and Textural Properties of Apple Pectin-Based Composite Formula with Xanthan Gum Modification for Preparation of Thickened Matrices with Dysphagia-Friendly Potential

by Huaiwen Yang, Chai-Chun Tsai, Jung-Shiun Jiang and Chi-Chung Hua

Polymers 2021, 13(6), 873; https://doi.org/10.3390/polym13060873 - 12 Mar 2021

Cited by 16 | Viewed by 4116

Abstract

Modifying the consistency of a given edible fluid matrix by incorporating food thickeners is a common nursing remedy for individuals with dysphagia when adequate water consumption is a concern. As apple pectin (AP) offers nutraceutical benefits, properly formulated apple pectin (AP)-based thickeners featuring [...] Read more.

Modifying the consistency of a given edible fluid matrix by incorporating food thickeners is a common nursing remedy for individuals with dysphagia when adequate water consumption is a concern. As apple pectin (AP) offers nutraceutical benefits, properly formulated apple pectin (AP)-based thickeners featuring xanthan gum (XG) can be superior candidates for preparation of dysphagia-friendly matrices (DFMs). Our recruited DFMs exhibit fluid-like behavior (loss modulus > storage modulus, G” > G’) at lower AP concentrations (2 and 5%, w/w); they turn into weak/critical gels (G’ ≈ G”) as the concentration becomes higher (9%). In contrast, XG-DFMs display gel-like attributes with G’ > G”, even at rather low concentrations (<1%) and become more resistant to sugar, Na⁺, and Ca²⁺ modifications. The composite matrix of AP1.8XG0.2 (constraint at 2%) exhibits a confined viscosity of 278 ± 11.7 mPa∙s, which is considered a DFM, in comparison to only AP- or XG-thickened ones. The hardness measurements of XG0.6 and AP1.2XG0.8 are 288.33 ± 7.506 and 302.00 ± 9.849 N/m², respectively, which potentially represent a promising formulation base for future applications with DFMs; these textural values are not significantly different from a commercially available product (p > 0.05) for dysphagia nursing administrations. Full article

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25 pages, 406 KiB

Open AccessReview

Understanding the Barrier and Mechanical Behavior of Different Nanofillers in Chitosan Films for Food Packaging

by João Pires, Camila Damásio de Paula, Victor Gomes Lauriano Souza, Ana Luísa Fernando and Isabel Coelhoso

Polymers 2021, 13(5), 721; https://doi.org/10.3390/polym13050721 - 26 Feb 2021

Cited by 76 | Viewed by 6962

Abstract

The continuous petroleum-based plastics manufacturing generates disposal issues, spreading the problem of plastic pollution and its rise in the environment. Recently, innovative techniques and scientific research promoted biopolymers as the primary alternative for traditional plastics, raising and expanding global bioplastic production. Due to [...] Read more.

The continuous petroleum-based plastics manufacturing generates disposal issues, spreading the problem of plastic pollution and its rise in the environment. Recently, innovative techniques and scientific research promoted biopolymers as the primary alternative for traditional plastics, raising and expanding global bioplastic production. Due to its unmatched biological and functional attributes, chitosan (Ch) has been substantially explored and employed as a biopolymeric matrix. Nevertheless, the hydrophilicity and the weak mechanical properties associated with this biopolymer represent a significant intrinsic restriction to its implementation into some commercial applications, namely, in food packaging industries. Distinct methodologies have been utilized to upgrade the mechanical and barrier properties of Ch, such as using organic or inorganic nanofillers, crosslinkers, or blends with other polymers. This review intends to analyze the most recent works that combine the action of different nanoparticle types with Ch films to reinforce their mechanical and barrier properties. Full article

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18 pages, 2364 KiB

Open AccessArticle

Conversion of Wheat Bran to Xylanases and Dye Adsorbent by Streptomyces thermocarboxydus

by Thi Ngoc Tran, Chien Thang Doan and San-Lang Wang

Polymers 2021, 13(2), 287; https://doi.org/10.3390/polym13020287 - 17 Jan 2021

Cited by 12 | Viewed by 3354

Abstract

Agro-byproducts can be utilized as effective and low-cost nutrient sources for microbial fermentation to produce a variety of usable products. In this study, wheat bran powder (WBP) was found to be the most effective carbon source for xylanase production by Streptomyces thermocarboxydus TKU045. [...] Read more.

Agro-byproducts can be utilized as effective and low-cost nutrient sources for microbial fermentation to produce a variety of usable products. In this study, wheat bran powder (WBP) was found to be the most effective carbon source for xylanase production by Streptomyces thermocarboxydus TKU045. The optimal media for xylanase production was 2% (w/v) WBP, 1.50% (w/v) KNO₃, 0.05% (w/v) MgSO₄, and 0.10% (w/v) K₂HPO₄, and the optimal culture conditions were 50 mL (in a 250 mL-volume Erlenmeyer flask), initial pH 9.0, 37 °C, 125 rpm, and 48 h. Accordingly, the highest xylanase activity was 6.393 ± 0.130 U/mL, 6.9-fold higher than that from un-optimized conditions. S. thermocarboxydus TKU045 secreted at least four xylanases with the molecular weights of >180, 36, 29, and 27 kDa when cultured on the WBP-containing medium. The enzyme cocktail produced by S. thermocarboxydus TKU045 was optimally active over a broad range of temperature and pH (40–70 °C and pH 5–8, respectively) and could hydrolyze birchwood xylan to produce xylobiose as the major product. The obtained xylose oligosaccharide (XOS) were investigated for 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and the growth effect of lactic acid bacteria. Finally, the solid waste from the WBP fermentation using S. thermocarboxydus TKU045 revealed the high adsorption of Congo red, Red 7, and Methyl blue. Thus, S. thermocarboxydus TKU045 could be a potential strain to utilize wheat bran to produce xylanases for XOS preparation and dye adsorbent. Full article

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15 pages, 2582 KiB

Open AccessArticle

Use of a Novel Polymer-Coated Steel as an Alternative to Traditional Can Manufacturing in the Food Industry

by Miguel A. Selles, Steven R. Schmid, Samuel Sanchez-Caballero, Maziar Ramezani and Elena Perez-Bernabeu

Polymers 2021, 13(2), 222; https://doi.org/10.3390/polym13020222 - 11 Jan 2021

Cited by 2 | Viewed by 3437

Abstract

Metal containers (both food and beverage cans) are made from huge steel or aluminum coils that are transformed into two- or three-piece products. During the manufacturing process, the metal is sprayed on both sides and the aerosol acts as insulation, but unfortunately produces [...] Read more.

Metal containers (both food and beverage cans) are made from huge steel or aluminum coils that are transformed into two- or three-piece products. During the manufacturing process, the metal is sprayed on both sides and the aerosol acts as insulation, but unfortunately produces volatile organic compounds (VOCs). The present work presents a different way to manufacture these containers using a novel prelaminated two-layer polymer steel. It was experimentally possible to verify that the material survives all the involved manufacturing processes. Thus tests were carried out in an ironing simulator to measure roughness, friction coefficient and surface quality. In addition, two theoretical ironing models were developed: upper bound model and artificial neural network. These models are useful for packaging designers and manufacturers. Full article

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2020

Jump to: 2022, 2021

13 pages, 2860 KiB

Open AccessArticle

The Degradation and Repolymerization Analysis on Solvolysis Liquefaction of Corn Stalk

by Weisheng Chen, Qinqin Zhang, Xiaoqi Lin, Kaisen Jiang and Dezhi Han

Polymers 2020, 12(10), 2337; https://doi.org/10.3390/polym12102337 - 13 Oct 2020

Cited by 14 | Viewed by 3874

Abstract

One of the most effective and renewable utilization methods for lignocellulosic feedstocks is the transformation from solid materials to liquid products. In this work, corn stalk (CS) was liquified with polyethylene glycol 400 (PEG400) and glycerol as the liquefaction solvents, and sulfuric acid [...] Read more.

One of the most effective and renewable utilization methods for lignocellulosic feedstocks is the transformation from solid materials to liquid products. In this work, corn stalk (CS) was liquified with polyethylene glycol 400 (PEG400) and glycerol as the liquefaction solvents, and sulfuric acid as the catalyst. The liquefaction conditions were optimized with the liquefaction yield of 95.39% at the reaction conditions of 150 °C and 120 min. The properties of CS and liquefaction residues (LRs) were characterized using ATR–FTIR, TG, elemental analysis and SEM. The chemical components of liquefied product (LP) were also characterized by GC–MS. The results indicated that the depolymerization and repolymerization reaction took place simultaneously in the liquefaction process. The depolymerization of CS mainly occurred at the temperature of <150 °C, and the repolymerization of biomass derivatives dominated at a higher temperature of 170 °C by the lignin derivatives repolymerization with cellulose derivatives, hemicellulose derivatives and PEG400 and self-condensation of lignin derivatives. The solvolysis liquefaction of CS could be classified into the mechanism of electrophilic substitution reaction attacked by the hydrogen cation. Full article

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13 pages, 1557 KiB

Open AccessArticle

Effect of Prebiotic Polysaccharides on the Rheological Properties of Reduced Sugar Potato Starch Based Desserts

by Dorota Gałkowska, Monika Południak, Mariusz Witczak and Lesław Juszczak

Polymers 2020, 12(10), 2224; https://doi.org/10.3390/polym12102224 - 27 Sep 2020

Cited by 6 | Viewed by 2587

Abstract

The aim of the study was to assess the possibility of using polysaccharides: inulin and polydextrose in combination with steviol glycosides as sucrose substitutes in starch-based desserts with reduced sugar content and to determine their influence on the rheological properties of these desserts. [...] Read more.

The aim of the study was to assess the possibility of using polysaccharides: inulin and polydextrose in combination with steviol glycosides as sucrose substitutes in starch-based desserts with reduced sugar content and to determine their influence on the rheological properties of these desserts. The samples (starch-milk desserts) were prepared from native potato starch, milk, dye, flavouring agent, and sucrose. The sucrose was partially or completely substituted with steviol glycosides and inulin or polydextrose. The rheological evaluation of the desserts was performed by determining pasting characteristics, viscosity curves, creep and recovery curves and mechanical spectra. Substitution of sucrose with prebiotic polysaccharides modified the rheological characteristics of the starch-milk desserts to a degree depending on the type and level of the substituting agent. Inulin reduced the peak viscosity of starch-milk paste, while it had no effect on the final viscosity of the product, contrary to polydextrose, which increased value of the latter parameter. The desserts exhibited a non-Newtonian, shear-thinning flow behaviour. The use of inulin, in both the highest and the lowest concentrations, significantly changed the consistency coefficient and the flow index values, while such a phenomenon was not observed in the case of polydextrose. The desserts with inulin showed increased values of the storage modulus and reduced susceptibility to stress, manifesting strengthened viscoelastic structure. The results indicate that the both prebiotic polysaccharides can serve as substitutes for sucrose in desserts with reduced sugar contents. Full article

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21 pages, 7197 KiB

Open AccessArticle

Synthesis of New Cyclodextrin-Based Adsorbents to Remove Direct Red 83:1

by José A. Pellicer, María Isabel Rodríguez-López, María Isabel Fortea, Vicente M. Gómez-López, David Auñón, Estrella Núñez-Delicado and José A. Gabaldón

Polymers 2020, 12(9), 1880; https://doi.org/10.3390/polym12091880 - 20 Aug 2020

Cited by 7 | Viewed by 3611

Abstract

Two cyclodextrins (CDs), γ– and hydroxypropyl (HP)–γ–CDs were used to synthesize new adsorbents by using epichlorohydrin (EPI) as cross-linking agent in order to remove Direct Red 83:1 (DR) from water. Both polymers were characterized in terms of Fourier spectroscopy, nuclear magnetic resonance, particle [...] Read more.

Two cyclodextrins (CDs), γ– and hydroxypropyl (HP)–γ–CDs were used to synthesize new adsorbents by using epichlorohydrin (EPI) as cross-linking agent in order to remove Direct Red 83:1 (DR) from water. Both polymers were characterized in terms of Fourier spectroscopy, nuclear magnetic resonance, particle size distribution and thermogravimetric analysis. Experimental data for both polymers were well fitted to the pseudo-second order and intraparticle diffusion model, indicating that in the adsorption both chemical and physical interactions are essential in the removal of DR. Three different isotherm models were analyzed, concluding that γ–CDs–EPI followed the Temkin isotherm and HP–γ–CDs-EPI the Freundlich isotherm, these results suggested that the adsorption was happening onto heterogeneous surfaces. The results of the Gibbs free energy showed that the adsorption was spontaneous at room temperature. In order to eliminate the remaining dye after the polymer treatment, and advanced oxidation process (AOP) was considered, achieving more than 90% of removal combining both mechanisms. Full article

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15 pages, 954 KiB

Open AccessArticle

The Effect of Germinated Sorghum Extract on the Pasting Properties and Swelling Power of Different Annealed Starches

by Hesham Alqah, M. S. Alamri, A. A. Mohamed, S. Hussain, A. A. Qasem, M. A. Ibraheem and I. A. Ababtain

Polymers 2020, 12(7), 1602; https://doi.org/10.3390/polym12071602 - 18 Jul 2020

Cited by 14 | Viewed by 4068

Abstract

Starches were extracted from chickpea (C.P.), corn (C.S.), Turkish bean (T.B.), sweet potato (S.P.S.), and wheat starches (W.S.). These starches exhibited different amylose contents. The extracted starches were annealed in excess water and in germinated sorghum extract (GSE) (1.0 g starch/9 mL water). [...] Read more.

Starches were extracted from chickpea (C.P.), corn (C.S.), Turkish bean (T.B.), sweet potato (S.P.S.), and wheat starches (W.S.). These starches exhibited different amylose contents. The extracted starches were annealed in excess water and in germinated sorghum extract (GSE) (1.0 g starch/9 mL water). The α-amylase concentration in the GSE was 5.0 mg/10 mL. Annealing was done at 40, 50, and 60 °C for 30 or 60 min. The pasting properties of annealed starches were studied using Rapid Visco-Analyzer (RVA), in addition to the swelling power. These starches exhibited diverse pasting properties as evidenced by increased peak viscosity with annealing, where native starches exhibited peak viscosity as: 2828, 2438, 1943, 2250, and 4601 cP for the C.P., C.S., T.B., W.S., and S.P.S., respectively, which increased to 3580, 2482, 2504, 2514, and 4787 cP, respectively. High amylose content did not play a major role on the pasting properties of the tested starches because sweet potato starch (S.P.S.) (22.4% amylose) exhibited the highest viscosity, whereas wheat starch (W.S.) (25% amylose) had the least. Therefore, the dual effects of granule structure and packing density, especially in the amorphous region, are determinant factors of the enzymatic digestion rate and product. Swelling power was found to be a valuable predictive tool of amylose content and pasting characteristics of the tested starches. The studied starches varied in their digestibility and displayed structural differences in the course of α-amylase digestion. Based on these findings, W.S. was designated the most susceptible among the starches and S.P.S. was the least. The most starch gel setback was observed for the legume starches, chickpeas, and Turkish beans (C.P. 2553 cP and T.B. 1172 cP). These results were discussed with regard to the underlying principles of swelling tests and pasting behavior of the tested starches. Therefore, GSE is an effortless economic technique that can be used for starch digestion (modification) at industrial scale. Full article

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14 pages, 3062 KiB

Open AccessArticle

A Smart Strategy to Improve t-Resveratrol Production in Grapevine Cells Treated with Cyclodextrin Polymers Coated with Magnetic Nanoparticles

by Lorena Almagro, Alicia De Gea-Abellán, María Isabel Rodríguez-López, Estrella Núñez-Delicado, José Antonio Gabaldón and María Angeles Pedreño

Polymers 2020, 12(4), 991; https://doi.org/10.3390/polym12040991 - 24 Apr 2020

Cited by 12 | Viewed by 3950

Abstract

One of the most successfully procedures used to increase the production of t-resveratrol in Vitis vinifera suspension-cultured cells is the application of cyclodextrins (CDs) and methyl jasmonate (MJ) as elicitors. In particular, β-CDs are characterized by their chemical structure which makes them [...] Read more.

One of the most successfully procedures used to increase the production of t-resveratrol in Vitis vinifera suspension-cultured cells is the application of cyclodextrins (CDs) and methyl jasmonate (MJ) as elicitors. In particular, β-CDs are characterized by their chemical structure which makes them special, not only by acting as elicitors, but also because they are compounds capable of trapping high added-value hydrophobic molecules such as t-resveratrol. However, the use of β-CDs as elicitors increases the production costs of this compound, making their industrial exploitation economically unfeasible. Therefore, the development of β-CDs recovery strategies is necessary to provide a viable solution to their industrial use. In this work, carboxymethylated and hydroxypropylated β-CDs have been used to form polymers using epichlorohydrin (EPI) as a cross-linking agent. The polymers were coated to Fe₃O₄ nanoparticles and were jointly used with MJ to elicit V. vinifera suspension-cultured cells. Once elicitation experiments were finished, a magnet easily allowed the recovery of polymers, and t-resveratrol was extracted from them by using ethyl acetate. The results indicated that the production of t-resveratrol in the presence of free carboxymethyl-β-CDs was much lower than that found in the presence of carboxymethyl-β-cyclodextrins-EPI polymer coated magnetic nanoparticles. In addition, the maximal levels of t-resveratrol were found at 168 h of elicitation in the presence of 15 g/L hydroxypropyl-β-CDs polymer coated magnetic nanoparticles and MJ, and non-t-resveratrol was found in the extracellular medium, indicating that all the t-resveratrol produced by the cells and secreted into the culture medium was trapped by the polymer and extracted from it. This work also showed that polymers can be regenerated and reused during three cycles of continuous elicitation since the induction and adsorption capacity of hydroxypropyl-β-CDs polymer-coated magnetic nanoparticles after these cycles of elicitation remained high, allowing high concentrations of t-resveratrol to be obtained. Full article

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29 pages, 2039 KiB

Open AccessEditor’s ChoiceReview

Recent Progress on Luminescent Metal-Organic Framework-Involved Hybrid Materials for Rapid Determination of Contaminants in Environment and Food

by Chi-Xuan Yao, Ning Zhao, Ji-Chao Liu, Li-Jun Chen, Jing-Min Liu, Guo-Zhen Fang and Shuo Wang

Polymers 2020, 12(3), 691; https://doi.org/10.3390/polym12030691 - 20 Mar 2020

Cited by 50 | Viewed by 7684

Abstract

The high speed of contaminants growth needs the burgeoning of new analytical techniques to keep up with the continuous demand for monitoring and legislation on food safety and environmental pollution control. Metal-organic frameworks (MOFs) are a kind of advanced crystal porous materials with [...] Read more.

The high speed of contaminants growth needs the burgeoning of new analytical techniques to keep up with the continuous demand for monitoring and legislation on food safety and environmental pollution control. Metal-organic frameworks (MOFs) are a kind of advanced crystal porous materials with controllable apertures, which are self-assembled by organic ligands and inorganic metal nodes. They have the merits of large specific surface areas, high porosity and the diversity of structures and functions. Latterly, the utilization of metal-organic frameworks has attracted much attention in environmental protection and the food industry. MOFs have exhibited great value as sensing materials for many targets. Among many sensing methods, fluorometric sensing is one of the widely studied methods in the detection of harmful substances in food and environmental samples. Fluorometric detection based on MOFs and its functional materials is currently one of the most key research subjects in the food and environmental fields. It has gradually become a hot research direction to construct the highly sensitive rapid sensors to detect harmful substances in the food matrix based on metal-organic frameworks. In this paper, we introduced the synthesis and detection application characteristics (absorption, fluorescence, etc.) of metal-organic frameworks. We summarized their applications in the MOFs-based fluorometric detection of harmful substances in food and water over the past few years. The harmful substances mainly include heavy metals, organic pollutants and other small molecules, etc. On this basis, the future development and possible application of the MOFs have prospected in this review paper. Full article

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18 pages, 3703 KiB

Open AccessArticle

Biodegradable Polyester Materials Containing Gallates

by Malgorzata Latos-Brozio and Anna Masek

Polymers 2020, 12(3), 677; https://doi.org/10.3390/polym12030677 - 18 Mar 2020

Cited by 16 | Viewed by 5588

Abstract

Gallates are widely used as antioxidants in the food and cosmetics industries. The purpose of the study was to obtain pro-ecological materials based on biodegradable polyesters, such as polylactide (PLA) and polyhydroxyalkanoate (PHA), and gallates. Gallates (ethyl, propyl, octyl, and lauryl) have not [...] Read more.

Gallates are widely used as antioxidants in the food and cosmetics industries. The purpose of the study was to obtain pro-ecological materials based on biodegradable polyesters, such as polylactide (PLA) and polyhydroxyalkanoate (PHA), and gallates. Gallates (ethyl, propyl, octyl, and lauryl) have not been used so far in biodegradable polymers as stabilizers and indicators of aging. This manuscript examines the properties of gallates such as antioxidant capacity and thermal stability. This paper also presents the following analyses of polymer materials: specific migration of gallates from polymers, SEM microscopy, differential scanning calorimetry (DSC), wide-angle X-ray diffraction, mechanical properties, surface free energy, and determination of change of color after controlled UV exposure, thermooxidation, and weathering. All gallates showed strong antioxidant properties and good thermal stability. Due to these properties, in particular their high oxidation temperature, gallates can be successfully used as polyester stabilizers. Biodegradable polyesters containing gallates can be an environmentally friendly alternative to petrochemical packaging materials. Full article

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12 pages, 5070 KiB

Open AccessArticle

Changes in the Crystallinity Degree of Starch Having Different Types of Crystal Structure after Mechanical Pretreatment

by Karina Dome, Ekaterina Podgorbunskikh, Aleksey Bychkov and Oleg Lomovsky

Polymers 2020, 12(3), 641; https://doi.org/10.3390/polym12030641 - 12 Mar 2020

Cited by 203 | Viewed by 16125

Abstract

This paper examines the effect of mechanical activation on the amorphization of starch having different types of crystalline structure (A-type corn starch; B-type potato starch; and C-type tapioca starch). Structural properties of the starches were studied by X-ray diffraction [...] Read more.

This paper examines the effect of mechanical activation on the amorphization of starch having different types of crystalline structure (A-type corn starch; B-type potato starch; and C-type tapioca starch). Structural properties of the starches were studied by X-ray diffraction analysis. Mechanical activation in a planetary ball mill reduces the degree of crystallinity in proportion to pretreatment duration. C-type tapioca starch was found to have the highest degree of crystallinity. Energy consumed to achieve complete amorphization of the starches having different types of crystalline structure was measured. The kinetic parameters of the process (the effective rate constants) were determined. The rate constant and the strongest decline in the crystallinity degree after mechanical activation change in the following series: C-type starch, A-type starch, and B-type starch. Full article

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18 pages, 3918 KiB

Open AccessArticle

The Incorporation of Carvacrol into Poly (vinyl alcohol) Films Encapsulated in Lecithin Liposomes

by Johana Andrade, Chelo González-Martínez and Amparo Chiralt

Polymers 2020, 12(2), 497; https://doi.org/10.3390/polym12020497 - 24 Feb 2020

Cited by 31 | Viewed by 4662

Abstract

Lecithin-encapsulated carvacrol has been incorporated into poly (vinyl alcohol) (PVA) for the purpose of obtaining active films for food packaging application. The influence of molecular weight (Mw) and degree of hydrolysis (DH) of the polymer on its ability to retain carvacrol has been [...] Read more.

Lecithin-encapsulated carvacrol has been incorporated into poly (vinyl alcohol) (PVA) for the purpose of obtaining active films for food packaging application. The influence of molecular weight (Mw) and degree of hydrolysis (DH) of the polymer on its ability to retain carvacrol has been analysed, as well as the changes in the film microstructure, thermal behaviour, and functional properties as packaging material provoked by liposome incorporation into PVA matrices. The films were obtained by casting the PVA aqueous solutions where liposomes were incorporated until reaching 0 (non-loaded liposomes), 5 or 10 g carvacrol per 100 g polymer. The non-acetylated, high Mw polymer provided films with a better mechanical performance, but less CA retention and a more heterogeneous structure. In contrast, partially acetylated, low Mw PVA gave rise to more homogenous films with a higher carvacrol content. Lecithin enhanced the thermal stability of both kinds of PVA, but reduced the crystallinity degree of non-acetylated PVA films, although it did not affect this parameter in acetylated PVA when liposomes contained carvacrol. The mechanical and barrier properties of the films were modified by liposome incorporation in line with the induced changes in crystallinity and microstructure of the films. Full article

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11 pages, 3793 KiB

Open AccessArticle

Tailoring Multi-Level Structural and Practical Features of Gelatin Films by Varying Konjac Glucomannan Content and Drying Temperature

by Dongling Qiao, Zhong Wang, Chi Cai, Song Yin, Hong Qian, Binjia Zhang, Fatang Jiang and Xiang Fei

Polymers 2020, 12(2), 385; https://doi.org/10.3390/polym12020385 - 8 Feb 2020

Cited by 8 | Viewed by 3055

Abstract

Here, we tailored the multi-level structural and practical (mechanical/hydrophilic) features of gelatin films by varying the konjac glucomannan (KGM) content and the film-forming temperatures (25 and 40 °C). The addition of KGM apparently improved the mechanical properties and properly increased the hydrophilicity. With [...] Read more.

Here, we tailored the multi-level structural and practical (mechanical/hydrophilic) features of gelatin films by varying the konjac glucomannan (KGM) content and the film-forming temperatures (25 and 40 °C). The addition of KGM apparently improved the mechanical properties and properly increased the hydrophilicity. With the lower temperature (25 °C), the increase in KGM reduced the gelatin crystallites of films, with detectable KGM–gelatin interactions, nanostructures, and micron-scale cracks. These structural features, with increased KGM and negligibly-occurred derivatizations, caused initially an insignificant decrease and then an increase in the strength, with a generally-increased elongation. The higher temperature (40 °C) could reduce the strength and slightly increase the elongation, related to the reduced crystallites of especially gelatin. With this higher temperature, the increase in KGM concurrently increased the strength and the elongation, mainly associated with the increased KGM and crystallites. Additionally, the increase in KGM made the film more hydrophilic; the multi-scale structural changes of films did not dominantly affect the changing trend of hydrophilicity. Full article

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