Browsing by Subject "Frozen"

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    Effect of industrial processing and storage on antioxidant activity of apricot (Prunus armeniaca v. bulida)
    (Springer, 2008) Jimenez Monreal, Antonia María; Martínez-Tomé, Magdalena; Egea, Isabel; Romojaro, Felix; Murcia Tomás, María Antonia; Tecnología de Alimentos, Nutrición y Bromatología
    The effect of different methods of conservation (frozen and canned) on the antioxidant properties of raw apricot was evaluated, and antioxidant activity of both types of processed fruit was monitored during 150 days of storage. The raw apricot exhibited the highest inhibition of oxidation according to the lipid peroxidation assay. The freezing process led to a slight loss of antioxidant activity, whereas canned apricots lost their antioxidant capacity. All samples showed a higher degree of protection in the deoxyribose assay (OH·) than BHA and BHT. The capacity of raw apricot to scavenge radical superoxide was higher than that of the antioxidant standards analysed, whereas the freezing and canning treatment decreased this capacity. The raw or processed apricots showed no capacity to scavenge hydrogen peroxide, nor offered oxidative stability to olive, sunflower and corn oils under the conditions of heating involved in the Rancimat test. Canned apricots showed higher ABTS·+ scavenging capacity than the raw fruit, perhaps as a result of the syrup absorbed by canned apricots. Raw apricots showed a very good capacity to protect linoleic acid against oxidation. During storage in frozen and canned apricots no important changes were detected in the different antioxidant activities assayed from 1 to 150 days.
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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).
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    Effect of industrial processing on chlorophyll content of broccoli
    (Wiley, 2000-06-14) Murcia, María Antonia; López Ayerra, Beatriz; Martínez-Tomé, Magdalena; García Carmona, Francisco; Tecnología de Alimentos, Nutrición y Bromatología
    Chlorophylls a and b and pheophytins a and b were quantitaty determined in raw, frozen (after blanching for 60, 120 or 150s) and canned florets and stems of broccoli. The chlorophyll a and b contents were 0.11 and 0.043g/kg fresh weight respectively in raw florets and 0.036 and 0.018g/kg respectively in stems. About 37.8% and 61.1% losses were incurred during the freezing process in florets and stems respectively, and 98.5%after canning as a consequence of industrial processing. After different blanching times the losses of chlorophyll a in frozen florets varied between 17.7 and 66.4%, while the losses of chlorophyll b varied between 23.2 and 48.8%. In the losses ranged from 55.5 to 75% and from 50 to 88.9% for chlorophylls a and b respectively. These losses resulted in an increase in pheophytin a and b levels in both florets and stems.