Browsing by Subject "Free radical"

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    Antioxidant activity of minimally processed (in modified atmospheres), dehydrated and ready-to-eat vegetables
    (Elsevier, 2009-08) Murcia, María Antonia; Jiménez-Monreal, A. M.; García-Diz, L.; Carmona, M.; Maggi , L.; Martínez-Tomé, Magdalena; Tecnología de Alimentos, Nutrición y Bromatología
    The antioxidant activity of vegetables subjected to minimal processing (in MAP, and intended for cooking or for use in salads), dehydrated condiments and ready-to-eat vegetables such as soups and purees, was assessed by reference to their ability to scavenge lipoperoxyl and hydroxyl radicals and Trolox-equivalent antioxidant capacity. In the case, the MAP vegetables the measurements were repeated during eight days of storage in a domestic refrigerator and after cooking (boiling, microwaving, pressure cooking, griddling, frying and baking). MAP vegetables had a good or very good antioxidant capacity, and showed no significant loss of antioxidant activity or scavenging capacity compared with fresh vegetables. The cooking treatments that keep the antioxidant activity of MAP vegetables are microwaving, sautéing and baking. The most aggressive method of cooking were steaming, boiling and frying. The dehydrated condiments (tablets) showed higher antioxidant activity than the ready-to-eat soup. The enrichment of stews and casseroles, with dehydrated vegetable tablets, and the consumption of soup or vegetable purees represent an increased antioxidant intake in our diet. Also ‘‘ready-to-eat” vegetable soups show antioxidant activity after they have been submitted to heat treatment to increase their shelf-life. They can be recommended as alternatives in our non-stop ‘‘life style”.
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    Antioxidant capacity of coffees of several origins brewed following three different procedures
    (Elsevier, 2007) Parras, P; Martínez-Tomé, Magdalena; Jimenez Monreal, AM; Murcia Tomás, MA; Tecnología de Alimentos, Nutrición y Bromatología
    The antioxidant capacity of coffees (Arabica and Robusta) from 12 different points of origin (Uganda, Papua, Jamaica, Ethiopia, Kenya, Puerto Rico, ‘‘Caracolillo’’ Puerto Rico, Nicaragua, Colombia, Vietnam, Brazil and Guatemala) and two decaffeinated coffees from Colombia and Brazil prepared by three commonly used procedures (espresso, filter and Italian) were evaluated and compared with antioxidant standards and other phenolic compounds which have been described in coffee. All the coffees studied were very effective as scavengers of lipoperoxyl and OH radicals. The results also showed that there are no significant differences (p < 0.05) between the three ways of brewing (espresso, filter and Italian). The H2O2 scavenging capacity was analysed in freshly made coffee and 6 h later, the antioxidant activity slightly increasing with time. The filtered coffee showed a greater capacity to react with H2O2 (p < 0.05) than the Italian and espresso coffees. All the coffee samples improved the oxidative stability of butter (Rancimat test), espresso and Italian coffee providing greater protection (p < 0.05) than the filtered beverages. The coffee beverages from different origins did not show significant differences during 28 days of storage as regards the autoxidation of linoleic acid. However, filter brews produced stronger antioxidant activity (p < 0.05) during storage than espresso and Italian brewing techniques. The TEAC value provided a ranking in decreasing order of antioxidant capacity for samples at 6 min: Vietnam, Uganda, Nicaragua, Colombia, Brazil, ‘‘caracolillo’’, Puerto Rico, Guatemala, Kenya, Papua, decaffeinated Colombia, Ethiopia, Jamaica, and decaffeinated Brazil. In general, decaffeinated coffees (Colombia and Brazil) showed lower TEAC values than coffees with caffeine. Filter and Italian coffee analysed after 6 min exhibited higher TEAC value than espresso coffees. All the coffees studied are good antioxidants regardless of their cost, origin and way in which they are brewed (espresso, filter or Italian), which is a point worth considering.