New Insights into Drying Technologies’ Applications in Food Processing

Dear Colleagues,

Drying food is one of the oldest methods of food preservation. However, it is still of interest to scientists and technologists, as the demand for dried food is growing. Originally, these foods were dried raw materials intended for consumption in a dried or hydrated state. Currently, drying is used to dry completely unusual products, such as honey, to produce dietary supplements consisting of dried extracts from particularly nutritionally valuable raw materials and reproducible drinks or whole dishes. New challenges presented by the market and consumers and faced by producers of dried food have caused the drying process to evolve in terms of its technical, technological, raw material and final product aspects. Spray drying, which is the basis for the production of food powders, and freeze drying, which allows the preservation of food’s structure and nutritional value, is undergoing particular innovation. Products obtained using these techniques constitute the basis of the rapidly growing convenience food market, including quickly reproducible foods.

Scientists are conducting research into the optimization of process parameters to develop high-quality dried products that maintain favorable energy parameters. They are looking for the possibility of using various methods to provide the heat necessary to evaporate water, with particular emphasis on methods involving the direct production of heat inside food (e.g. via a microwave field, ohmic heating or infrared heating). This is intended to intensify the heat supply process and increase the overall energy efficiency of the heating process. Research is being carried out regarding the use of various pre-treatment treatments, e.g., using a pulsed electric field or ultrasound, the aim of which is to reduce the resistance to water movement in the dried material. Issues related to ensuring the high quality of dried products and their preservation during storage are becoming ever-more important. This has led to greater research into the coating of dried fruits, especially powders and freeze-dried products, which are particularly susceptible to changes in storage conditions.

Undoubtedly, a new look at the drying process is the analysis of changes in the structure of dried food, the physical properties of dried products (e.g. hygroscopicity) and the analysis of the phase changes that dried food ingredients undergo. This is possible thanks to the development of microscopic techniques, internal structure imaging (e.g. tomography) and thermogravimetric methods. The knowledge gained through these analyzes allows us to actively design the properties of dried materials, tailored to the needs of the consumer, which is also a new approach to food drying

Therefore, this Special Issue is open to the publication of research results and/or evaluations regarding new challenges and new technological approaches related to drying technologies and their application in food products.

Dr. Dorota Nowak
Dr. Ewa Jakubczyk
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Foods is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• drying technologies
• thermal processing
• food dehydration
• food preservation
• radio frequency
• inductive heating

Title: The pretreatment as a tool to accelerate the freeze-drying and improve of dried products properties
Authors: Ewa Jakubczyk; Dorota Nowak
Affiliation: Department of Food Process Engineering and Management, Warsaw University of Life Sciences
Abstract: The aim of the paper is to describe different pretreatment method which can be applied before freeze-drying. The effect of size reduction, mechanical degradation of peel, PEF, ultrasounds, blanching, osmotic dehydration, high-pressure on the course of drying process and different properties of final products. The applied treatment should be correlated with the biological structure of plant materials which is the main resistance to water transfer during drying.