Ana Bernardo Álvarez

The effects of ripening stage and processing systems on vitamin C content in sweet peppers (Capsicum annuum L.)

Morrón pepper of ‘Fresno de la Vega’ (Capsicum annuum L.) is a big sweet variety cultivated in the province of León (northwestern Spain). Changes in vitamin C content of this variety of pepper as a function of ripeness, storage and different preservation systems were studied. The ascorbic acid content increases in peppers as they ripen. For green mature, breaker and red peppers values of 107.3±1.84, 129.6±3.11 and 154.3±7.56 mg/100 g edible portion were found. The vitamin C content for green mature and breaker peppers stored at room temperature (20°C) increased up to 10 days of storage, reaching similar values as those obtained for red peppers direct from the plant. However, stored red ripe peppers showed a significant loss in vitamin C content, around 25%. Refrigeration at 4°C for up to 20 days did not change the ascorbic acid content, except for red peppers, which showed losses around 15%. The ascorbic acid content was altered in response to the preservation procedures assayed. Reductions of 12% and 20–25% during the water blanching and canning process, respectively, were observed. Ascorbic acid retention during freezing was 60%, increasing when the product was previously blanched (87%). Dehydration of peppers resulted in an 88% decrease in ascorbic acid content, whereas freeze-drying did not cause significant losses.

Thermal inactivation of Bacillus cereus spores affected by the solutes used to control water activity of the heating medium

The heat resistance of B. cereus spores (ATCC 7004, 4342 and 9818) over a wide temperature range (92-125 degrees C) in aqueous solutions of NaCl, LiCl, sucrose and glycerol at different water activities (1.00-0.71) was investigated. Sodium chloride in the heating medium tended to protect the spores of B. cereus against heat. The z-values increased significantly (P < 0.05) at and above a concentration of 4.0 M. The effects of LiCl were lower than those caused by the NaCl at the same a(w) values. An increase in z-values was observed. but the differences were only statistically significant (P<0.05) at the highest concentration tested (5.0 M). A concentration of sucrose 0.87 M caused in all cases a reduction in D-values, which was most pronounced for strains 4342 and 9818. With increasing concentration of sucrose ( > 0.87 M), the D-values showed an increase, although only those obtained for strain 4342 in sucrose solutions 2.22 M were higher than those found in pure water. The z-values were significantly higher (P < 0.05) when sucrose was added at concentrations above 1.42 M, except for strain 4342. When a(w) was lowered from 0.96 to 0.71 with glycerol, D-values obtained gradually increased, about 30, 50 and 60 fold for 4342, 7004 and 9818 strains, respectively. No significant effect on z-values were detected.