The Effects of Oven Dehydration on Bioactive Compounds, Antioxidant Activity, Fatty Acids and Mineral Contents of Strawberry Tree Fruit

Abstract

In this study, the effects of oven dehydration on chemical and bioactive properties, fatty acids, polyphenolic compounds and minerals of sandal strawberry tree fruit were investigated. While total carotenoid contents of the sandal strawberry tree fruit are determined between 4.20 (120 °C) and 5.43 µg/g (70 °C), tannin amounts of the sandal strawberry tree fruit were recorded between 5.13 (control) and 6.37% (70 and 120 °C). While total phenolic contents of dehydrated sandal strawberry tree fruit were found between 444.16 (120 °C) and 665.13 mgGAE/100 g (control), total flavonoid amounts of dehydrated sandal strawberry tree fruit were recorded between 592.91 (control) and 788.71 mg/100 g (120 °C). Antioxidant activity values of fruit ranged from 4.10 (120 °C) to 7.30 mmol TE/kg (control). Both total phenolic amounts and antioxidant activity values of untreated (control) sandal strawberry tree fruit were found to be higher than dehydrated ones, and a linear relationship was determined between the total phenolic amounts of the samples and their antioxidant activities. The highest amounts of phenolic compounds (ferulic acid, resveratrol and kaempferol) were detected in strawberry tree fruit dehydrated at 70 °C, followed by the control group and fruit dehydrated at 120 °C in decreasing order. Gallic acid, 3,4-dihydroxybenzoic acid, catechin, caffeic acid and rutin were the main constituents of the strawberry tree fruit, followed by syringic acid, p-coumaric acid and ferulic acid in descending order. Palmitic, stearic and oleic acid amounts of dehydrated strawberry tree fruit oils compared to the control were observed to increase with the applied temperature, while the contents of polyunsaturated fatty acids (linoleic and linolenic) decreased. In general, the mineral content of dehydrated strawberry tree fruit increased compared to the control. Since the oil, carotenoid, total phenol and phenolic component contents of sandalwood tree fruit are higher in the sample subjected to dehydration at 70 °C, this temperature can be considered as the ideal one for drying. In addition, considering the fatty acids, heat treatment at 120 °C can be preferred.