RESUMO
The aim of this study was to determine the oxidative stability of oil extracted from red carp fish frozen up to 9 months at -18°C. To assess oil stability of red carp fish, the analytical indexes and Fourier transform infrared (FTIR) spectroscopy were used. These methodologies used provided similar conclusions. Before frozen storage, the composition of fatty acids showed that red carp oil is a good source of polyunsaturated fatty acids (PUFAs) such as linoleic acid (C18:2ω-6: 5.29% of total fatty acid), linolenic acid (C18:3ω3: 3.53% of total fatty acid), arachidonic acid (C20:4ω6: 3.68% of total fatty acid), eicosapentaenoic acid (C20:5ω-3, EPA: 4,06% of total fatty acid), and docosahexaenoic acid (C22:6ω-3: 3.02% of total fatty acid). During frozen storage, the free fatty acid and peroxide value increased, respectively, from 1.35% to 8.06% in oleic acid and 3.77 to 18.62 meq O2/kg in lipid, while the ratio of PUFA/SFA and polyene index decreased, respectively, from 0.58 to 0.25 and 0.30 to 0.09. The triglycerides also decreased with frozen duration. Therefore, for good fish quality, red carp fish must be stored for <3 months at -18°C.
RESUMO
The objective of this study was to determine the effect of oven and traditional roasting on the polyphenol content, antioxidant activity, lipid quality, proximate composition and mineral content of fermented cocoa beans. Results showed that traditional roasting significantly decrease (p < 0.05) the polyphenol content and antioxidant activity of cocoa beans. The analysis of oil showed that oven and traditional roasting significantly increase (p < 0.05) the peroxide and thiobarbituric acid values of cocoa butter and that traditional roasting samples were the most deteriorated. Oven and traditional roasting for 10 min reduce the iodine value of the oil, but increase its acidity. The proximate and mineral composition of cocoa beans was also seriously affected during cooking. Drying and oven roasting for 5 and 10 min; and drying and traditional roasting for 5 min appear to be the best processing methods of cocoa beans for production of cocoa based foods like chocolate.
RESUMO
The effect of boiling and roasting on the lipid quality, proximate composition, and mineral content of African walnut seeds (Tetracarpidium conophorum) was assessed. Results indicated that the quality of walnut oil significantly (p < .05) reduces with the treatments. Oils extracted from DBWN 60 min (Dried and boiled walnuts 60 min) and FBWN 60 min (Boiled fresh walnuts 60 min) were the most altered. The proximate composition and mineral content of walnut seeds was also significantly affected (p < .05) by the treatments. This study reveals that, thermal processing has significant effects on the nutrients and quality of lipids of walnut oil. DTRWN 60 min (Dried and traditionally roasted walnuts 60 min), DORWN 60 min (Dried and oven roasted walnuts 60 min), and TRFWN 30 min (traditionally roasted fresh nuts 30 min) are the best methods for cooking walnut because they preserve the quality of its lipids and some of the nutrients.
