Recent Developments in the Hybridization of the Freeze-Drying Technique in Food Dehydration: A Review on Chemical and Sensory Qualities

Abstract

Freeze-drying is an excellent method for dehydration due to its benefits, including increased shelf-life, unique texture, and, in particular, good nutritive quality. However, the applicability of traditional freeze-drying systems in the food industry is still challenging owing to their prolonged drying duration, extraordinary energy usage, and high process cost. Therefore, the need to upgrade or develop conventional freeze-dryers for common or sophisticated food structures is ever-increasing. Enhancements to the freeze-drying process can significantly speed up drying and reduce energy consumption while maintaining phytochemicals, physical quality, and sensory attributes in final products. To overcome the downsides of conventional freeze-drying, hybrid freeze-drying methods were introduced with a great potential to provide food products at shorter drying durations, lower costs, and environmental friendliness while resulting in the same nutritive and sensory qualities as that of conventional freeze-drying in special circumstances. An overview of the most current improvements, adaptations, and applications of hybrid freeze-drying in food dehydration is given here. In this review, comparative studies are offered to characterize the drying process from the standpoint of chemical quality and sensory attributes. All the reviewed studies confirmed that the nutritional and sensory qualities of the end product can be retained using hybrid freeze-drying almost to the same extent as using single freeze-drying. It was also inferred that hybrid freeze-drying can surpass conventional freeze-drying and allow for obtaining dried products with characteristics typical of raw material if operating parameters are optimized based on product quality and energy usage.

Exploratory Testing of Energy-Saving Characteristics of Large-Scale Freeze-Drying Equipment

“…Although freeze-drying is a recognized technique for producing high-quality products, its long drying time, high energy consumption, and high processing costs have restricted its large-scale application [17]. Combining microwave, pulsed electric field, explosion puff, and infrared as pretreatments for freeze-drying could improve the drying rate, reduce energy consumption, and preserve nutritional content and colors [18]. Cao et al used microwave heating at 1, 1.5, and 2 W/g to process barley grass, observing that MFD (microwave freeze-drying) preserved chlorophyll, flavonoid, color, and odor, while reducing energy usage during freeze-drying [19].…”

A High-Efficiency Radio-Frequency-Assisted Hot-Air Drying Method for the Production of Restructured Bitter Melon and Apple Chips

“…In recent years, various emerging drying technologies were considered and commercialized to enable the introduction of energy-saving approaches without compromising on the quality of the finished products. Several novel techniques including dielectric drying [10], infrared-freeze drying [11], low-pressure superheated steam drying [12], as well as impingement jet drying [13] have been implemented for the processing of foodstuffs.…”