Proximate analysis and fatty acid composition of eight commercially important species of Lake Superior fish were determined. Palmitic acid (C16:0) was the predominant saturated fatty acid, accounting for 68–79% of total saturated acids. Oleic acid (C18:1) was the most abundant monounsaturated fatty acid. Linoleic acid (C18:2), linolenic acid (C18:3), eicosapentaenoic acid (C20:5) and docosahexaenoic acid (C22:6) were the predominant polyunsaturated fatty acids. Brining, smoking and refrigerated storage caused a reduction in total lipid, but only a small loss in n‐3 fatty acids. The data revealed that most Lake Superior fish examined were excellent sources of polyunsaturated fatty acids with very high levels of omega‐3 (n‐3) fatty acids, especially eicosapentaenoic and docosahexaenoic acids.

Linolenic acid is the unstable component of soybean [Glycine max (L.) Merr.] oil responsible for undesirable odors and flavors commonly associated with poor oil quality. The objective of this study was to determine the inheritance of fatty acid composition in A5, a soybean mutant with the lowest linolenic acid percentage of any genotype that has been evaluated for the character. Reciprocal crosses were made between A5 and two soybean cultivars, Weber and Pella. The parents were significantly different for all fatty acids, except palmitic acid in A5 and Pella. The F1 seeds, F2 seeds from F1 plants, and seeds from replicated tests of F2‐derived lines were evaluated for the percentage of palmitic, stearic, oleic, iinoleic, and linolenic acids. The F1 seeds from reciprocal crosses differed significantly for oleic, linoleic, and linolenic acids in both crosses, and for palmitic acid in the Weber cross, which indicated a maternal effect on composition for these fatty acids. Cytoplasmic inheritance of fatty acid composition was not observed, based on the lack of reciprocal cross differences for fatty acid composition in the analysis of F2 seeds from F1 plants. The composition of the F2‐derived lines exhibited a continuous distribution typical of a quantitative character for each of the fatty acids in both crosses. There were 14% of the F2‐derived lines in the Pella cross and 10% in the Weber cross that had a linolenic acid percentage as low as A5. Heritability estimates on a plot basis averaged across crosses from the analysis of F2‐derived lines were 33% for palmitic, 5% for stearic, 54% for oleic, 59% for linoleic, and 58% for linolenic acid. The results indicated that fatty acid composition should be considered a quantitative character in crosses that involve A5 as a parent.

The role of lipoxygenase in causing lipid oxidation in lake herring was studied. Lipid oxidation was measured by assaying for 2-thiobarbituric acid-reactive substances (TBARS}, and lipoxygenase activity was measured by a spectrophotometric 1470 nm) method. Lipoxygenase activity was highest in light muscle, lowest in skin and intermediate in dark muscle. Light muscle contained the highest percentage of phospholipids (PL} and the least total lipid. The percentage of PL was lowest and total lipids were highest in the skin. Eicosapentaenoic acid and docosahexaenoic acid were found in larger amounts in PL than in triglycerides. Heat treatment rapidly inactivated lipoxygenase. After a 5-min heating period, lipoxygenase was totally inactivated in most cases. TBARS data indicated that samples heated at 80~ for 1.5-2.0 min were more stable than samples heated at 80~ for 2.5-5.0 min, suggesting that heat accelerated nonenzymatic oxidation.

Four soybean oils (SBO) with different fatty acid (FA) compositions were tested for stability during intermittent heating and frying of bread cubes. None of the oils was hydrogenated or contained any additives. Two of the oils were from common commercial varieties. The other two oils were from seed developed in a mutation breeding program and included the line A5, which contained 3.5% linolenate, and the line A6, which contained 20% stearate. Each oil (450 g) was heated to 185 C in a minifryer. Bread cubes were fried at the beginning of heating, and half were stored at −10 C to preserve freshness. The second half was stored at 60 C for 14 days. Heating was continued for 10 hr/day for four days. After 40 hr of heating, an additional 30 g of bread cubes were fried. According to sensory evaluations of the fried bread cubes, peroxide values of oil extracted from the cubes and conjugated diene values of the oils, the A5 and A6 oils were more stable than those from the commercial varieties. Small differences occurred in the flavor and oxidative stability of the cubes fried after 40 hr of heating the oils. Large differences between A5 and A6 and the commercial varieties occurred after storage of bread cubes for 14 days.

The fatty acid composition of developing soybean (Glycine max [L.] Merrill) seeds was evaluated in the mutant line, A6, and its parent, FA8077. Seeds of both lines were harvested at 2‐day intervals from 15 to 39 days after flowering (DAF) and at 4‐day intervals from 39 DAF until maturity. Significant differences between the two lines were observed for stearic and oleic acid percentages at 19 DAF. The maximum difference between the lines was at 25 DAF, when A6 had 45.4% and FA8077 had 4.1% stearic acid. The increase in stearic acid percentage in A6 was accompanied by a decrease in oleic acid to 16.8% at 25 DAF, compared with 53.7% oleic acid for FA8077. The two lines did not differ in development of palmitic, linoleic and linolenic acids. The protein and oil content of mature seeds were similar for the two lines.