The effects of treatment on quality parameters of smoothie-type 'Hayward' kiwi fruit beverages

Kiwi fruits contain high levels of bioactive compounds (ascorbic acid, total phenols, anthocyanins, chlorophylls, carotenoids, tannins, flavanols and flavonoids), which are important to preserve them in preparation of purees, beverages, juices and other varieties of food products. The purpose of the present study was to evaluate physicochemical parameters, including antioxidant and binding properties during different treatments in the preparation of 'Hayward' kiwi fruit smoothie-type beverages. Preparation of smoothie-type beverages from kiwi fruits involved the following stages: adding of different percentages of sugar content inside the mass, mixture and then freezing during long storage. The bioactive compounds were determined in fresh and treated smoothies. To assess the antioxidant capacity, four different methods were applied: 2, 2'-azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) diammonium salt (ABTS⁺), Ferric-reducing/antioxidant power (FRAP), Cupric reducing antioxidant (CUPRAC) and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, showing high correlation coefficients with polyphenols from 0.894 till 0.969, because polyphenols mostly influence the antioxidant capacity. The decrease of total phenolic compounds (39%) and anthocyanins (31%) was higher than in ascorbic acid (25%) in preparation of smoothies after long cold storage. The proposed above preparation of smoothies preserved the decrease of bioactive compounds. The binding abilities of extracted polyphenols to human serum albumin (HSA) of smoothies determined by 3D-fluorescence and FTIR spectroscopy correlated with their amounts. The investigated kiwi fruit smoothies can be used as a source of antioxidants.