Antioxidant Activity and Quality of Apple Juices and Puree After in vitro Digestion

Dietary recommendations include the consumption of fresh apples and processed apple based products mainly for the antioxidant properties associated to the polyphenols, and vitamin C content. Thermal treatment, generally used to extend shelf life of fruit based foodstuff, can affect the quality. 5-hydroxymethylfurfural (5-HMF), reducing sugars, ascorbic acid, and the total antioxidant activity in bio available fraction after in vitro digestion, have been evaluated in 16 apple-based nectars (fruit content: 30-60%), 15 apple-based juices (fruit content 100%) and 5 apple-based puree. Observed data indicate a 5-HMF values ranging from 0.06 mg/L in juices to 28.61 mg/L in nectars. The reducing sugar amount did not vary significantly between the three analysed typology of apple derivatives, while the ascorbic acid content was quite high compared to reported literature data. The antioxidant activity after an in vitro digestion showed values ranging from 0.21 to 7.68 mmol of Trolox in juices, and puree, respectively.