Retention of berry fruits quality by freeze – drying: challenges and results
2021
Stevanović, Snežana M. | Dimitrijević, Aleksandra | Zlatanović, Ivan
Berry fruits are important crops in temperate regions such as R. Serbia and occupy an important position in the agriculture production. These attractive fruits are favored for their excellent taste and can be considered a very rich source of micronutrients and bioactive compounds with beneficial effect on health. However, berry fruits are highly perishable foods and have a rather limited shelf life, since they easily undergo degradation reactions by microorganisms, because of their high moisture content. The challenge is how to preserve this fruit in postharvest period and prolong availability during the year. Freeze-drying (lyophilization) is a modern process of drying that is increasingly used in industry of food processing. The process of water removing is done from the frozen samples by sublimation of ice under vacuum. The aim of this paper is to point out the benefits of freeze-drying in comparison to air-drying, through analysis of effect of two drying methods on the relevant parameters of quality of the strawberry, raspberry and blackberry fruits. The content of vitamin C, physicochemical properties, degree of rehydration, as well as evaluation of sensory characteristics of the fruits after freeze-drying and air-drying at 60°C were determined. The obtained results showed significantly better retention of vitamin C, physicochemical and sensory characteristics after freeze-drying of the berry fruits than air-drying. The degree of rehydration was also significantly higher in the freeze-dried samples. Generally, it may be concluded that freeze-drying represent a very suitable method for preserving these delicate berry fruits.
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