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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.
- Long-term frozen storage and pasteurization effects on strawberry polyphenols contentPublication . Oliveira, Ana; Coelho, Marta; Alexandre, Elisabete M. C.; Almeida, Domingos P. F.; Pintado, ManuelaThe profile of the strawberry polyphenols was analysed on fresh strawberry, immediately after freezing or after pasteurization and during frozen storage of strawberry at -20 A degrees C for 360 days. Freezing increased the extractability of (-)-epigallocatechin gallate (60 %), (-)-epicatechin (48 %) and ellagic acid (51 %) and decreased the pelargonidin-3-glucoside (18 %). Direct pasteurization of fresh strawberry increased the extractability for (-)-epigallocatechin gallate (73 %), (-)-epicatechin (45 %) and ellagic acid (143 %) and decreased for pelargonidin-3-glucoside (16 %). During storage at -20 A degrees C for 360 days the extractable levels of pelargonidin-3-rutinoside, (-)-epigallocatechin gallate, (+)-catechin, (-)-epicatechin and ellagic acid decreased by 17, 20, 37, 65 and 80 %, respectively, while those of pelargonidin-3-glucoside increased 13 %. Changes in polyphenols content, produced by pasteurization after 360 days frozen storage, were minimal. Polyphenols content decreased during storage of strawberry pieces at -20 A degrees C for 360 days, while the thermal treatment applied after freezing storage did not induce any significant change.
- Phytochemicals preservation in strawberry as affected by pH modulationPublication . Oliveira, Ana; Gomes, Maria Helena; Alexandre, Elisabete M. C.; Poças, Fátima; Almeida, Domingos P. F.; Pintado, ManuelaStrawberries purees are incorporated in foods and subjected to pH modulation according to the expected final food matrix. The effect of pH on strawberry polyphenols stored at 4 and 23 degrees C for 90 days was evaluated. Total antioxidant activity and total phenolics content were only affected by time according to a first order model. The pH 4.5 induced higher decrease in (-)-epigallocatechin gallate (71% and 79%) and quercetin-3-glucoside (29% and 36%), for both storage temperatures. For pH 2.5 and 3.0, ellagic acid increased 84% for 4 degrees C. and 185% for 23 degrees C. Anthocyanins concentration changes along storage were well described by first order model. The pH value of 2.5 presented the lower kinetic constant rate where cyanidin-3-glucoside, pelargonidin-3-glucoside and pelargonidin-3-rutinoside had a k = 0.04, 0.05 and 0.03 day(-1). Lower storage temperature (4 degrees C) and lower pH (2.5) were the best condition for the preservation of polyphenols in pasteurized strawberry during a 90-day storage period.
- Peach phytochemicals availability during yoghurt shelf-timePublication . Oliveira, Ana; Alexandre, Elisabete M. C.; Coelho, Marta; Lopes, Cláudia; Almeida, Domingos P. F.; Pintado, Manuela E.
- Effect of controlled atmosphere and storage temperature on the phenolics and carotenoids of pasteurized peach puréesPublication . Oliveira, Ana; Alexandre, Elisabete M. C.; Coelho, Marta; Lopes, Cláudia; Almeida, Domingos P. F.; Pintado, M. E.
- 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.
- Auditing functional phytochemicals during fruit processingPublication . Oliveira, A.; Pintado, M.; Almeida, Domingos P. F.
- Nutritional Audit of peach and strawberry preparates for dairy applicationsPublication . Lopes, Cláudia; Oliveira, Ana; Pintado, M. E.; Almeida, Domingos P. F.
- Peach polyphenol and carotenoid content as affected by frozen storage and pasteurizationPublication . Oliveira, Ana L.; Alexandre, Elisabete M. C.; Coelho, Marta; Barros, Rui M.; Almeida, Domingos P. F.; Pintado, ManuelaThe profile of polyphenol and carotenoid of peach were analysed on fresh fruits, immediately after freezing or after pasteurization, and during frozen storage at -20 ºC for 360 days. Freezing did not affect the concentration of polyphenols or carotenoids. Pasteurization of fresh and frozen samples induced an increase in the extractability of chlorogenic acid (38% and 24%) and of zeaxanthin (336% and 127%) and a decrease of lutein (22% and 56%) and b-cryptoxanthin (32 and 51%). Total antioxidant capacity and total phenolic content changed by less than 20% after frozen storage for 360 d. However, total carotenoid content decreased 41% and 48% in unpasteurized and pasteurized samples, after the same storage period. Long term storage induced an increase in the extractability of (+)-catechin (47%) and zeaxanthin (90%) and a decrease in neochlorogenic acid (59%), chlorogenic acid (39%), quercetin-3-glucoside (21%), lutein (24%) and b-cryptoxanthin (40%). Pasteurization of frozen samples promoted a decrease in the concentration of neochlorogenic acid (91%), chlorogenic acid (87%) and quercetin-3-rutinoside (71%) and increase in lutein (16%), b-cryptoxanthin (42%) and b-carotene (31%). Peach should be stored for periods no longer than 230 d, since pasteurization after that, induced a higher decrease in neochlorogenic, chlorogenic acids and quercetin-3-rutinoside content.
- Desenvolvimento de uma metodologia de auditoria nutricional ao processamento do morangoPublication . Oliveira, Ana; Pintado, M. E.; Almeida, Domingos P. F.