From nutritional and functional point of view is important to understand the consequences of processing in food composition in order to select the best technological conditions required for the preservation of fruit health benefits.This study was performed involving the study of pasteurization, matrix pH modification, modified atmosphere, long term storage after freezing and pasteurization of frozen fruit at different points of storage. It was possible to observe that strawberry polyphenols were more susceptible to degradation by pasteurization than peach phytochemicals, mainly due to anthocyanins. Storage under low conditions of pH (2.5) allowed to obtain higher stability of strawberries anthocyanins, while intermediate pH of about 3.0 and 3.5 were the best conditions for peach carotenoids stability and higher pH values of 4.5 led to higher content of neochlorogenic and chlorogenic acid on peach. In general, the low content of oxygen was the best condition for phytochemicals preservation, mainly 100 kPa N2 for anthocyanins and carotenoids. Long storage periods (90 d) showed a decrease on the content of all phytochemicals, at higher rate when temperatures where higher as expected. Fruit used in processing can be stored under frozen conditions, reaching periods of 360 d. This process permited easier extractability for some phytochemicals increasing them, but became more susceptible to degradation by the followed process of pasteurization.The final step of processing encompasses the incorporation of fruit preparates in dairy matrices. Fruit polyphenols when incorporated in lactic matrices like yoghurt interacted with milk proteins namely β-lactoglobulin (β-LG) and with polysaccharides typically added to fruit formulations as stabilisers. Model mixtures pure polyphenol-protein-polyssacharide proved that pectin have a detrimental impact by decreasing significantly the phenolic content and consequently its antioxidant activity. When the model mixtures and fruit yoghurt where subjected to simulated gastrointestinal system, polyphenols revealed a higher bioaccessibility once in the presence of protein and polyssacharide. This means that food components may form complexes with polyphenols that allow protection from degradation through the digestive process making them more bioavailable.
Round table COST Positive FA1403 with ISEKI-Food Association about bioactives
Tuesday, 15 March 2016, 17:30 CET
Manuela Pintado et al
Portuguese Catholic University