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Colour and texture are very important quality properties of all foods. In this work, the influence was investigated of different types of pectin on colour and textural properties in strawberry jams and low-calorie strawberry jams containing fructose and aspartame or fructose syrup and aspartame. The highest anthocyanin content and total phenol content were detected in strawberry jam samples prepared with low methoxy amidated pectin. During storage, after 4 and 6 weeks at both storage temperatures, room temperature and 4°C, anthocyanin content and total phenol content decreased. Also, free radical scavenging activity decreased during storage. As far as the texture parameters are concerned, namely firmness, consistency and cohesiveness, the highest values were found in strawberry jam samples prepared with high methoxyl pectin.

In this study, influence of addition of sugars and chlorogenic acid on anthocyanin content in blackberry juice during storage was investigated. Samples of juice were prepared with addition of sugars (saccharose, fructose, glucose and trehalose), chlorogenic acid, and both chlorogenic acid and sugars. Control sample was juice without additives. Samples were investigated for their anthocyanin content, polyphenol content, antioxidant activity and color change. After stabilization, positive influence of trehalose and glucose addition on anthocyanin content was observed, while samples with saccharose and fructose had lower anthocyanin content than control sample. During storage anthocyanin content decreased but the same tendency remained. Addition of chlorogenic acid caused increase of anthocyanin content. In some cases, this effect was enhanced with addition of sugars, like in the case of glucose and trehalose, and that tendency was observed also during storage. PRACTICAL APPLICATION Addition of different additives, like in our case sugars and chlorogenic acid, could be a possible tool for improvement of anthocyanin stability. Improvement of stability of anthocyanins is not only important for the color of food products but anthocyanins also have antioxidant properties.

The objective of this study was to investigate the influence of simple sugar addition including (glucose, G; fructose, F; sucrose, S; and trehalose, T) on the total polyphenol content (TPC) and antioxidant activity (AOA) of apple purée processed by freezing and freeze-drying and stored for 6 months. The apple polyphenol profile was mostly preserved in the freeze-dried samples with sugar addition during 6 months of storage, whereas the polyphenol profile in frozen samples consists only of quercetin glycosides, of which rutin had the largest share. After 6 months, the highest level of polyphenols was detected in frozen 'Idared' and 'Fuji' apple purée with addition of T 5% (12.2 and 16.7 mg/100 g FW, respectively), whereas in freeze-dried apple purée the highest TPC was in 'Idared' and 'Fuji' with addition of T 1% (16.3 and 13.6 mg/100 g FW, respectively). Results indicate that sugar addition before processing could have potential for enhancing product quality.