Physicochemical and Antioxidant Properties of Fermented and Freeze-Dried Vegetable-Based Snacks

Abstract

Featured Application: This study demonstrates the potential application of lactic acid fermentation combined with freeze-drying for the development of vegetable snacks with enhanced potential functional properties. The proposed approach has the potential to be applied in the food industry to valorize second-grade or surplus vegetables into value-added products, thereby supporting sustainable production and reducing food waste. Furthermore, the developed snacks have the potential to serve as a convenient source of bioactive compounds and postbiotic metabolites, aligning with current consumer demand for minimally processed foods. Growing demand for natural and functional foods has increased interest in fermentation-based technologies. This study aimed to develop and characterize fermented and freeze-dried vegetable snacks from beetroot, potato, zucchini, and cucumber. The evaluation included physicochemical properties (pH, titratable acidity, and color), microbiological quality, antioxidant potential using TEAC, ABTS and FRAP assays, along with determination of total phenolic content (TPC), vitamin C, sensory acceptability and attributes. Fermentation resulted in a significant decrease in pH and an increase in titratable acidity of samples, confirming active growth of lactic acid bacteria (LAB), with counts exceeding 6 log10 CFU/g after five days. Freeze-drying preserved the acidic profile and influenced color parameters. Antioxidant capacity varied depending on the raw material, with beetroot showing the strongest potential to scavenge the ABTS•+, while cucumber was characterized by the highest vitamin C content (175.24 mg/100 g dry matter. Zucchini exhibited moderate antioxidant capacity, whereas potato showed the lowest values. Sensory analysis indicated high acceptance of beetroot and potato snacks, associated with balanced flavor and texture, while cucumber and zucchini samples were rated lower due to softer texture and higher acidity. The combination of lactic fermentation and freeze-drying enables the production of vegetable snacks with desirable sensory properties and enhanced functional potential.