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- Effect of modified atmosphere on phytochemical profile of pasteurized peach puréesPublication . Oliveira, Ana; Coelho, Marta; Alexandre, Elisabete; Gomes, Maria Helena; Almeida, Domingos P. F.; Pintado, ManuelaPeach phytochemical profile was analysed during 90 days storage under three different gas mixtures: 10 kPa O2+90 kPa N2, 100 kPa N2 and air (78 kPa N2+21 kPa O2+0.03 kPa CO2) for both 4 and 23 °C. The antioxidant activity increased when peach purée was stored under air at 4 °C and 100 kPa N2 at 23 °C, while total phenolic content was not affected by atmospheres. Total carotenoids were more stable for 100 kPa N2, where it decreases 48 and 58% respectively for 4 and 23 °C. The content of (+)-catechin decreased 42% for 10 kPa O2 at 4°C, remaining constant in other atmospheres. Chlorogenic and neochlorogenic acids were well preserved in atmospheres containing oxygen, presenting an increase of 14 and 24% for 10 kPa O2 at 4°C. The higher content of carotenoids was obtained for 100 kPa N2 at 23 °C. Principal component analysis shows that atmospheres variance was associated with carotenoids while storage time was more related with total phenolics and total antioxidant capacity.
- Incorporation of strawberries preparation in yoghurt: impact on phytochemicals and milk proteinsPublication . Oliveira, Ana; Alexandre, Elisabete M. C.; Coelho, Marta; Lopes, Cláudia; Almeida, Domingos P. F.; Pintado, Manuela E.An immediate decrease in the total antioxidant activity (23%) and total phenolic content (14%) was observed after addition of strawberry preparations to yoghurt. The total anthocyanin content did not change immediately, but decreased 24% throughout the yoghurt shelf-life. The individual compounds, (+)-catechin (60%), (-)-epicatechin (60%), kaempferol (33%) and quercetin-3-rutinoside (29%) decreased after 24 h in the yoghurt made with the strawberry preparation. During the remaining period of storage these compounds increased by 47%, 6%, 4% and 18%, respectively. Pelargonidin-3-glucoside decreased 49% after 28 d. Immediately after the addition of the strawberry preparation to yoghurt, beta-lactoglobulin decreased to values lower than the limit of detection and alpha-lactalbumin by approximately 34%, and was reduced further slowly throughout yoghurt self-life. An immediate interaction between the carrageenan present in the strawberry preparation and beta-LG was observed. The variations of both polyphenols and protein in the presence of carrageenan and the potential interactions were discussed.