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The effects of storage temperature and relative humidity on the quality of Swiss chard (Beta vulgaris, type cycla) were investigated. Quality was assessed through determinations of water content, weight loss, chlorophyll content, pH, titratable acidity, soluble solids content and sensory evaluations. Storage conditions were 4 and 18C and 43, 86 and 98% relative humidities (RH). The quality of chard leaves was unacceptable after three days of storage at 18C, independent of the RH. Chard leaves kept at 4C and 86 and 98% RH remained acceptable for 9 days. The dehydration suffered by samples kept at 4C and 43 % RH turned them unacceptable after 4 days of storage.

The effects that ripening stage have on the apparent viscosity and ascorbic acid retention in squash pulp exposed at cooking process were analyzed. Total soluble solids contents were taken as indicative of ripening degree. In the raw material, water contents ranged from 79 to 96%, but no significant differences were observed among samples grouped as unripe, ripe and overripe. The ascorbic acid contents of pulp increase with increases in soluble solids contents. Pulp from unripe and ripe squash had similar apparent viscosity values; however, lower viscosity values were obtained in pulp from overripe squash. During heat treatment, significant changes in the apparent viscosity values of pulp from unripe and ripe squash were observed. Heat penetration properties of squash pulp indicate correlation between the inverse slope of the straight portion in the heat penetration curves on a semilog plot (fh) and thermal diffusivity values (α) with dry matter content, but no correlation was found with squash maturity degree. High ascorbic acid retention (82%) in pulp held for 30 min at 95C was found independently of squash maturation degree. PRACTICAL APPLICATIONS Knowing the rheological behaviour and the ascorbic acid retention of butternut squash pulp during cooking process could be used as a valuable information previously to make decisions for use this crop as a food supply.

The biochemical properties and the characteristics of heat-induced gelation of actomyosin from mature and immature squid were investigated. Both Mg(2+)-ATPase activity and reduced viscosity values of actomyosin showed no significant differences between mature and immature squids. A lower content of myosin heavy chain and a higher content of a 160 kDa component were observed in the SDS-PAGE 10% pattern of actomyosin from immature specimens. Gelation of both actomyosins at 10 mg mL(-)(1) protein concentration was optimal at 80 degrees C and pH 6.0. The highest rigidity was reached at 0.25 M KCl with actomyosin from both mature and immature squids. Irrespective of the heating temperature, ionic strength, and pH condition, the rigidity of mature squid actomyosin gel was greater than that of immature squid. Scanning electron micrographs of gels obtained with actomyosin from mature squids showed a better tridimensional structure than those of immature squids.

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