Original article: The effect of freezing at −18 °C and −70 °C with and without ascorbic acid on the stability of antioxidant in extracts of apple and orange fruits
2010
Polinati, Renata Madureira | Faller, Ana Luísa Kremer | Fialho, Eliane
The influence of low temperature and storage time on the antioxidant capacity of standard solutions and apple and orange extracts was evaluated. In addition, the effects of ascorbic acid (AA) addition to the fruit extracts in terms of antioxidant capacity, AA content and soluble and hydrolyzable polyphenol contents were also analysed. Polyphenol contents in both apple and orange extracts were stable during storage period, which reflected also in the antioxidant capacity stability. Freezing at −18 °C did not result in different retention rates for polyphenols, AA and antioxidant capacity when compared to freezing at −70 °C. However, vitamin C content in orange juice, without AA addition, slightly increased along the experimental period (10 days). Thus, this study shows that it may not be necessary to measure the antioxidant capacity immediately after the preparation of fruit extracts or antioxidant standard solutions.
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