Freeze-Drying of Plant-Based Foods

Abstract

Vacuum freeze-drying of biological materials is one of the best methods of water removal, with final products of highest quality. The solid state of water during freeze-drying protects the primary structure and the shape of the products with minimal volume reduction. In addition, the lower temperatures in the process allow maximal nutrient and bioactive compound retention. This technique has been successfully applied to diverse biological materials, such as meats, coffee, juices, dairy products, cells, and bacteria, and is standard practice for penicillin, hormones, blood plasma, vitamin preparations, etc. Despite its many advantages, having four to ten times more energy requirements than regular hot air drying, freeze-drying has always been recognized as the most expensive process for manufacturing a dehydrated product. The application of the freeze-drying process to plant-based foods has been traditionally dedicated to the production of space shuttle goods, military or extreme-sport foodstuffs, and specialty foods such as coffee or spices. Recently, the market for ‘natural’ and ‘organic’ products is, however, strongly growing as well as the consumer’s demand for foods with minimal processing and high quality. From this perspective, the market for freeze-dried plant-based foods is not only increasing but also diversifying. Freeze-dried fruits and vegetables chunks, pieces, or slices are nowadays majorly used in a wide range of food products such as confectionaries, morning cereals, soups, bakeries, meal boxes, etc. Instant drinks are prepared out of freeze-dried tea, coffee, or even from maple syrup enriched with polyphenol concentrated extracts from trees. The possibilities are endless. In this review, the application of freeze-drying to transform plant-based foods was analyzed, based on the recent research publications on the subject and personal unpublished data. The review is structured around the following related topics: latest applications of freeze-drying to plant-based foods, specific technological problems that could be found when freeze-drying such products (i.e., presence of cuticle; high sugar or lipid concentration), pretreatments and intensification technologies employed in freeze-drying of plant-based foods, and quality issues of these freeze-dried products.

Improvement of quality properties of cemen paste of pastirma by lyophilized red cabbage water extract

“…Compared with other drying methods in terms of maintaining the final product quality, the lyophilization method is recommended as the best choice for drying fruits and vegetables. Because the absence of liquid water, lack of oxygen under vacuum and low temperatures, most of the deterioration reactions slow down or are practically stopped, aroma losses are minimized (Bhatta, Stevanovic Janezic, & Ratti, 2020). In previous studies, it has been reported that the lyophilization technique has significantly benefited in preserving phenolic compounds, color pigments (anthocyanins, carotenoids, etc.…”

“…In previous studies, it has been reported that the lyophilization technique has significantly benefited in preserving phenolic compounds, color pigments (anthocyanins, carotenoids, etc. ), ascorbic acid, aroma components, and textural properties in fruits and vegetables (Bhatta et al., 2020; Gümüşay, Borazan, Ercal, & Demirkol, 2015; Palacios, Guillamón, García‐Lafuente, & Villares, 2014; Rajkumar et al., 2017; Rodrigues, Dos Santos, Bergamasco, & Madrona, 2018).…”

Polyphenols composition, antioxidant and antimicrobial properties of Pinus sylvestris L. shoots extracts depending on different drying methods

“…As the outer layer is covered by epicuticular waxex, freezedrying of whole shoots could contribute to build-up of internal pressure and lead up to material damage, making it more susceptible to external conditions (Bhatta et al, 2020). Therefore, it can be expected that raw material type also has a decisive impact on the stability of pigments during drying with different methods.…”

Effect of Freeze-Drying on Quality and Grinding Process of Food Produce: A Review

“…In the last few decades, a number of reviews have been conducted on the subject freeze-drying. However, most of these reviews have centered on the quality characteristics of the food product and improving the freeze-drying process with limited emphasis on the effect of the drying process on the grinding characteristics of the food [20][21][22] Therefore, the primary objective of this review was to provide an overview of the effect of freeze-drying on the quality attributes of agricultural products and to state the influence of freeze-drying on the grinding process. A review of the mathematical models for freeze-drying will also be provided.…”