Colour, bioactive compounds and antioxidant capacity of mixed beverages based on fruit juices with milk or soya
2014
Andrés, V. | Villanueva, M. J. | Mateos-Aparicio, I. | Tenorio, M. D.
Fruit beverages are a source of phytochemicals, vitamins and minerals, with a high hydration capacity. The aim of this study was to evaluate mixed beverages based on fruit juices with milk or soya regarding their colour (L*, a*, b*), antioxidant compounds (carotenoids, ascorbic acid and polyphenols) and antioxidant activity. The b* parameter, which is associated with a yellow-orange colour, presented a positive correlation with β-carotene concentration (r2 = 0.917). β-Carotene was the main carotenoid (58–3547 mg•l-1), followed by zeaxanthin (37–97 µg•l-1) and lutein (5–15 µg•l-1). The concentration of deliberately added ascorbic acid ranged between 78 mg•l-1 and 993 mg•l-1. The HPLC methods used proved to be suitable for the analysis of carotenoids and vitamin C in these mixed beverages. Polyphenols are naturally present in these mixed beverages (151–503 mg•l-1). The antioxidant capacity of each mixed beverage was assessed in vitro by the ferric reducing antioxidant power (FRAP) method and ranged from 65 mmol•l-1 to 376 mmol•l-1 (expressed as Trolox equivalents). The antioxidant capacity of these beverages was mainly due to the vitamin C (97.7%) and, in a minor proportion, due to polyphenols (2.3%). Discriminant analysis was applied to these samples of mixed beverages and samples from ‘tropical’ and ‘soyjuice’ groups were found to be the best classified into their commercial denominations.
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