Optimization of drying temperature for the assessment of functional and physical characteristics of autumn olive berries

Abstract

Autumn olive is a rich source of carotenoids, phenolic acids, and flavonoids and is used for the prevention of many diseases. The effects of drying conditions on the functional properties of autumn olive were investigated for the first time. The optimum drying conditions were 81°C and 1 m/s to have the maximum experimental values of 6,378.98 mg GAE/100 g, 862.94 µg/g, 11.38 mmol ISE/g and 7.06 for TPC, LC, FRAP, and ΔE, respectively. Midilli and Peleg models described better the drying and rehydration behaviors, respectively. Six major phenolic compounds such as catechin, fumaric acid, gallic acid, hesperidin, and quercetin were identified. The drying treatment showed overall positive effects on the individual phenolic compounds. The microstructure analysis showed that the dried autumn olive berries presented collapse, deformed, and wrinkled cells. These findings revealed that the convective drying of autumn olive berries at 81°C is adequate to have functional fruits utilizable in the industries. Practical applications The drying conditions to preserve the phenolic compounds and antioxidant features of autumn olive berries were determined. The one-factor response surface methodology and mathematical models were successfully carried out. The optimum drying conditions were figured out, and Midilli and Peleg models were the most fitted models to describe the drying and rehydration behaviors of autumn olive berries, respectively. The dried fruit is a rich source of nutraceutical and can be employed as multipurposes' fruit in many industries.