Content Of Trans C18 Research Articles

Formation of trans fatty acids during the frying of chicken fillet in corn oil

To assess effects of heated edible oils on intake of trans fatty acids (TFAs); the formation of TFAs in cooking conditions was investigated by a frying system model, in which chicken fillet was fried in a commercial corn oil at 170 °C, for 12 frying cycles. The main TFAs detected in chicken fillet were trans C18:2 fatty acids (FAs) and trans C18:3 FAs, which exhibited no significant differences among the frying cycles. Besides, the content of trans C18:1 FAs were very low in all samples on different frying cycles. The intake of TFAs was estimated to be 0.06 g/100 g when chicken fillet fried in this process was consumed. These results suggest that an ordinary frying process upon a commercial corn oil has little impact on the daily TFAs intake.

CONTENT OF TRANS C18:1 AND TRANS C18:2 ISOMERS AND CIS9TRANS11 C18:2 (CLA) IN FAT BLENDS

ABSTRACT The content ofTrans C18:1,Trans C18:2 and cis9trans11 C18:2 (CLA) in the marketed fat blends was evaluated by capillary gas chromatography and silver thin‐layer chromatography. For comparison, the level of these acids was also determined in commercial butter, purchased at the same time. The content ofTrans C18:1 in fat blends showed that half of the examined products containedTrans C18:1 at 1.9–4.4%, while the other half contained 8.2–24.2%Trans fatty acids. The fat blends with a high total content ofTrans C18:1 were characterized by a high proportion ofTrans 6–8 andTrans 9 isomers. TheTrans 9 C18:1 in these products constituted 15.0–22.5% of the totalTrans C18:1. The level ofTrans C18:2 in fat blends examined ranged from 0.3 to 1.1%. Seven of the 18 tested fat blends contained, apart from cis‐trans andTrans‐cis C18:2, alsoTrans‐trans C18:2 in the 0.03–0.4% range. In all fat blends examined, CLA was present. The products with a low level ofTrans C18:1 contained CLA at 0.3–1.0%. The content of CLA in the fat blends with high level ofTrans C18:1 did not exceed 0.3%.

Effect of feeding on conjugated cis Δ9, trans Δ11‐octadecadienoic acid and other isomers of linoleic acid in bovine milk fats

Almost 2000 bovine milk fats were analysed by gas chromatography to investigate the influence of typical barn and pasture feeding of cows on trans-C18:2 isomers (with at least one trans double bond) including the conjugated linoleic acid cis delta9, trans delta11 (c9,t11) as well as the cis delta9, cis delta12 linoleic acid. Moreover, small cow herds were used to determine the influence of pasture Feeding with young and older grass as well as the impact of an energy deficit or the variation of quantity and technical treatment of fed rape-seed on the content of C18:2 isomers in milk fat. The contents of trans-C18:2 (w/o c9,t11) and c9,t11 in 1756 milk fats on average amounted to 0.63% resp. 0.75%. These contents increased from barn feeding, in winter with 0.46% resp. 0.45% over the transiton period in spring and late autumn with 0.66% resp. 0.76% to pasture feeding in summer with 0.87% resp. 1.20%. Milk fat samples from bulk milk obtained weekly during one year from 4 large West German milk collection areas confirmed and completed the data found for the 1756 milk fats. The percentage of linoleic acid with a mean value of 1.24 (n = 1756) varied irregularly during the different feeding periods. The content of the conjugated linoleic acid c9,t11 could be raised considerably up to triple the normal amount by different changes in feeding. However, the content of trans-C18:1 fatty acids was strongly increased as well, respectively.

Steady-State Rates of Linoleic Acid Biohydrogenation by Ruminal Bacteria in Continuous Culture

Ruminal biohydrogenation of linoleic acid was determined in fermenters with a continuous culture of microorganisms. Rates of biohydrogenation and changes of fatty acids in culture were measured during steady-state concentration of linoleic acid that was achieved by continuous infusion of linoleic acid into the fermenters. A number of trans and cis isomers were identified using a GLC equipped with an infrared detector. The infusion of linoleic acid resulted in a substantial increase in the content of trans-C18:1 and a lesser increase in cis-C18:1. The major trans peak consisted of a mixture of n-9 and n-7 isomers. Biohydrogenation of infused linoleic acid averaged 77%. There was evidence of fatty acid loss, as determined by a decrease in the recovery of linoleic acid after 8h of infusion. Addition of C18:2n-6 had no major effect on the VFA production by ruminal microorganisms. The results were similar to those measured in vivo, indicating that artificial fermenters were reliable predictors of fatty acid metabolism in vivo.