Freeze-Drying of Fruits and Vegetables in Food Industry: Effects on Phytochemicals and Bioactive Properties Attributes - A Comprehensive Review

ABSTRACT

Freeze-drying has become an important technology used to extend shelf-life and to preserve food nutritional quality. It is most recommended for high-value foods and those containing heat-sensitive ingredients. However, to our knowledge, there are significant differences in the retention of phytochemicals in various fruits and vegetables during freeze-drying, which need to be summarized and explained. Thus,the evolution of the bioactive substances and free radical scavenging abilities of fruits and vegetables based on the freeze-drying procedure will be explored in this review. Furthermore, the stability of bioactive ingredients in freeze-dried products during storage will be also deeply reviewed in this paper by comparing the presented studies in these aspects. The comprehensive review of the research progress of freeze-drying techniques and the challenges in developing freeze-dried products is discussed.

KEY FINDINGS

• The freezing step causes the degradation of phenolic compounds and also causes the release of bound phenolic compounds in correlation with the cell wall.

• Prolonging the drying step causes the degradation of ascorbic acid and anthocyanins in some food matrix.

• Generally, the faster freezing rate, the higher drying temperature, and the shorter drying time can produce freeze-dried fruits and vegetables with higher retention of phytochemicals and bioactive activity.

• During storage, the small pore structure causes degradation of carotene and other compounds sensitive to oxygen, and the collapse freeze-dried sample showed higher retention of those substances.

KEYWORDS:

• Vacuum freeze-drying
• storage
• fruits and vegetables
• nutrition
• antioxidant

Acknowledgments

This work was financially supported by the Agricultural Science and Technology Innovation Program, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences (CAAS-ASTIP-2022-IFST).

Additional information

Funding

The work was supported by the Chinese Academy of Agricultural Sciences [CAAS-ASTIP-2022-IFST].