Browsing by Subject "Amino acids"

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    Comparison of the antioxidant and pro-oxidant activities of broccoli amino acids with those of common food additives
    (Wiley, Society of Chemical Industry, 2001-08) Martínez Tomé, Magdalena; Murcia Tomás, María Antonia; García Carmona, Francisco
    The antioxidant and pro-oxidant activities of broccoli amino acids were compared with those of common food additives. In decreasing order, the data showed that Asp, SMC, GABA, Glu, Gln, Pro, Phe, Leu, Lys, Arg, Asn, Val, Ile, His, Ser, Gly, Orn and Ala, when dissolved in water at concentrations of 0.5 and 0.05 mM, partially inhibited damage to deoxyribose in the presence of ferric-EDTA and H2O2. In contrast, Tyr and Thr acted as pro-oxidants in this system. The amino acids present in broccoli had no hydrogen peroxide-scavenging effect. When dissolved in water, methanol or ethanol, SMC, Glu, Thr, Gln, Ser, GABA, Pro, Ala, Ile, Phe, Asp, Orn and Tyr inhibited lipid peroxidation. However, Asn, Val, Arg, Leu, Lys, His and Gly were not effective in decreasing peroxidation at concentrations of 0.5 and 0.05 mM. Asp > SMC > Ala > Phe > Hys > Orn > Gln = Ser > Lys > Leu = GABA = Gly > Tyr > Arg = Thr > Val > Asn > Pro > Ile > Glu (p < 0.025) showed scavenging activity towards hypochlorous acid protecting al-antiproteinase against inactivation. In this paper it has been established that some amino acids premixed with propyl gallate increase its hypochlorous acid-scavenging capacity, while other amino acids have an additive effect with propyl gallate, permitting smaller quantities of propyl gallate to be used as food additives in some products which contain these amino acids.
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    Effect of industrial processing on amino acid content of broccoli
    (Wiley, Society of Chemical Industry, 2001) Murcia Tomás, María Antonia; López Ayerra, Beatriz; Martínez Tomé, Magdalena; García Carmona, Francisco; Tecnología de Alimentos, Nutrición y Bromatología
    The levels of amino acids in broccoli stems and florets before and after various blanching times (in the case of freezing) and after bottling have been studied to elucidate to what extent nutrient quality is affected by industrial processing. The following amino acids (mg kg-1 fresh weight) were identified by ion exchange chromatography in raw broccoli florets: glutamine (1338), proline (732), asparagine (578), valine (310), arginine (296), isoleucine (204), threonine (169), leucine (166), phenylalanine (159), aspartic acid (140), lysine (127), alanine (122), tyrosine (105), S-methylcysteine (96), histidine (89), ornithine (59), glutamic acid (44), -y-aminobutyric acid (31), glycine (11) and serine (0.2). Raw stems contained the same amino acids but at lower levels (p < 0.05). The levels of all these amino acids fell during both industrial processes studied (bottling and freezing after blanching for 60, 90, 120 and 150 s), particularly in the frozen samples (losses of 50-70% in the florets and 20-50% in the stems). In summary, losses of broccoli amino acids were lower if blanching times were kept short. The optimal blanching time at 94 C for florets and stems intended for freezing was 90 s, and this did not result in any great loss of nutritional value related to amino acid content. Bottled florets had greater nutritional value than those frozen after being exposed to the longest blanching times (120 and 150 s).