Browsing by Author "Almeida, Domingos P.F."
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- Phytochemical composition and antioxidant activity of peach as affected by pasteurization and storage durationPublication . Oliveira, Ana; Pintado, Manuela; Almeida, Domingos P.F.Fruit are very perishable and are often preserved as heat-processed foods. Clingstone peach [Prunus persica (L.) Batsch ‘Catherine’] fruit were heat-treated at 90 C for 5 min and stored under aseptic conditions at room temperature (ca. 22 C) for 90 days. Significant reductions in total carotenoids were observed immediately after pasteurization but total antioxidant activity and the concentration of total phenolics were unaffected. Pasteurization induced significant reductions in the concentration of protocatechuic acid (from 10.2 to 5.8 mg/g fw), zexanthin and b-cryptoxanthin. Significant reduction in antioxidant activity, expressed as ascorbic acid equivalents, from 0.52 to 0.25 mg/g fw, was observed during storage of pasteurized peach for 90 days. Total phenolics, expressed as gallic acid equivalents, decreased during storage from 0.57 to 0.28 mg/g fw and total carotenoids decreased from 4.0 to 1.3 mg/g fw. Procyanidin B1 increased from 15.8 to 26.8 mg/g fw and chlorogenic acid and neochlorogenic acid increased 35 and 43%, respectively. ( )-Epicatechin decreased during storage from 13.1 to 4.0 mg/g fw and quercetin- 3-glucoside from 7.3 to 4.4 mg/g fw. All carotenoids decrease significantly with the exception of zeaxanthin, which increased during storage. Storage duration strongly affected the concentration of phenolics and carotenoids in pasteurized peach.
- Postharvest water relations in cut rose cultivars with contrasting sensitivity to high relative air humidity during growthPublication . Fanourakis, Dimitrios; Carvalho, Susana M.P.; Almeida, Domingos P.F.; Kooten, Olaf van; Doorn, Wouter G. van; Heuvelink, EpA constant highrelativeairhumidity (RH) during cultivation can strongly reduce the vase life in some cutrosecultivars. We studied three contrastingcultivars in their tolerance to high RH in order to analyse in detail the waterrelations during postharvest and better understand this genotypic variation. Plants were grown at moderate (60%) and high (95%) RH, and cut flowers were placed in water immediately after cutting. Flowers of cv. Pink Prophyta grown at high RH did not open throughout vase life, while flower opening of cvs. Frisco and Dream was not affected by preharvest RH. Cultivation at high RH resulted in about 80% shorter vase life in Pink Prophyta, whereas in Dream and Frisco the negative effect was considerably smaller (15 and 9% shorter vase life, respectively). The shorter vase life and reduced flower opening of cutroses grown at high RH was due to a higher rate of transpiration both in the light and dark periods. It was found that the leaves of Pink Prophyta grown at high RH could partly close their stomata upon lowering of the water potential or when flower stalks were fed with abscisic acid, but stomata remained far more open than in leaves grown at moderate RH. The RH during cultivation did not affect stem hydraulic conductivity and its recovery after air emboli induction. Preventing vascular occlusion largely alleviated the high-cultivation-RH effect on vase life and flower opening, showing that the effect of high-cultivation-RH becomes only important if water uptake is limited.