Trans fatty acid isomers and the trans‐9/trans‐11 index in fat containing foods

Abstract

To determine trans fatty acid (TFA) distribution of contemporary foods, especially regarding individual trans octadecenoic acids (trans C18:1), 339 German foods of six categories (semi-solid fats, deep-fried potato products, bakery products, confectioneries, instant products and butter) were analysed using two GC methods. Results showed a high variation of TFA content between and within the categories containing between 0 and 40.5% of FAME except in butter, which is a source of natural TFA. The mean TFA values were below 2.0% of FAME, however, bakery products contained 4.5% and butter fat 3.2%, respectively. In addition, the distribution of individual trans C18:1 differed. In samples containing ruminant fat (butter and various confectioneries), vaccenic acid (t11-C18:1, t11) predominated, while in foods containing industrially hydrogenated fats, elaidic acid (trans-9, t9-) and t10-C18:1 were the major trans isomers.. This was reflected by a low t9/t11 index of 0.3 and 0.5 in butter and ruminant fat containing confectioneries, respectively, whilst the highest index was observed in shortenings and deep-fried potato products at 5.2 and 6.8, respectively. In conclusion, the TFA content of foods available on the German market is generally declining, but substantial variations are present. The t9/t11 index could be used as an indicator to determine ruminant fat.Practical applications: A number of studies provide evidence that a high TFA intake, particularly of industrial origin, adversely affects human health. The TFA content of foods could be reduced due to the introduction of several mandatory regulations and modifications regarding the hydrogenation process of oils. The most abundant dietary TFA are the isomers of trans C18:1. Unfortunately, the differentiation of these isomers is not yet very common, though the trans C18:1 profile differs depending on its origin (bacterial hydrogenation in the rumen or industrial hydrogenation). To date, data for TFA content including the trans C18:1 profile of different food categories are limited. The present study confirmed that the TFA contents in German foods are declining. However, TFA are still elevated, especially in bakery products and confectioneries, which are produced using mainly industrial but also ruminant fats. Therefore, the t9/t11 index imparts important information on the source of TFA in processed foods.

Effects of Dietary Trans Fatty Acids on Fat Accumulation and Metabolic Rate in Rat

“…These reports suggested that hydrogenated fat could suppress diet-induced obesity. In this study, TFAs comprised 35.6 of total dietary FAs, and ELA, not vaccenic acid C18:1 trans-11 , was supposed to constitute the majority accurate figure not known of trans-formed C18:1 FA because industrial hydrogenation of vegetable oils produces ELA rather than vaccenic acid 25 . However, anti-obesity effects of TFAs that contained ELA were not observed in this study for the following reasons.…”

Comparison between Experimentally Determined Total, Saturated and <i>Trans</i> Fat Levels and Levels Reported on the Labels of Cookies and Bread sold in Brazil

“…These foods are also cited as some of the main trans fat sources in the diet [59,60]. In this context, analyzing these foods can enable not only the inference of trans fat intake from Brazilian breads and cookies but also form the basis of a discussion about reducing the isomer in these products.…”

Composición de ácidos grasos en algunos alimentos fritos y aceites de fritura y factores relacionados, en un sector universitario de Medellín-Colombia

“…En aquellos aceites altamente insaturados, el tratamiento térmico induce isomerización de los áci-dos grasos linoleico y el linolénico hasta los AGT C18:1 (elaídico:t-9 y vaccénico:t-11) (25), ambos asociados con riesgo para ECV (26)(27). Se han reportado proporciones de AGT de 0,23-1,10% en aceite de girasol sometido a 200°C durante 40 minutos (28) cifran que incrementaron hasta 3,2% cuando se aumentó la temperatura del aceite a 250°C durante el mismo tiempo (29).…”