Storage Stability of Bioactive-Enriched Freeze-Dried Gala Apples: Functional Properties, Sensory Evaluation, and Enzymatic Browning

A storage study of healthy snack potential for osteoporosis prevention was carried out. Freeze-dried apple flesh after impregnation (IMP) using 93.8% sea buckthorn (SB) juice, 1:99 of inulin:SB juice ratio, 4% calcium lactate addition, at 30°C for 120 min was prepared. The study aimed to monthly investigate the characteristic changes of IMP compared to freeze-dried fresh apple (FA) and that after dipping with 1% ascorbic acid (FA+AA) as controls, during 3 months of storage at 25°C in an incubator. Throughout the 3-month storage period, IMP consistently exhibited higher total phenolic content and stronger antioxidant activity compared to the control samples. After 3 months, significant degradation of these values was observed (p<0.05), confirmed by results from composition of phenolics and carotenoids, as well as the presence of polyphenol oxidase and peroxidase activities, and the development of browning color or appearance. The freshly prepared IMP also contained more than 81 times calcium content than controls (p<0.05). Sensory evaluation highlighted moderate to rather high overall acceptability of IMP, most-likely due to calcium involvement in maintaining its crispiness during storage compared to controls. Due to its significantly high antioxidant content, calcium enrichment, and stable sensory properties, IMP has the potential to serve as a functional snack for osteoporosis prevention and increased calcium intake. These findings support the potential application of SB-enriched apples as calcium-rich, antioxidant-preserving functional snacks.