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Abstract
Intake of high amounts of trans fatty acids (TFAs) have been positively correlated with increased risk of several chronic diseases. The main aim of this research project was to produce structured lipids (SLs) suitable for formulation of trans-free margarines. The oils/fats used were stearidonic acid (SDA) soybean (SDASO), high stearate soybean (HSSO), cottonseed (CO), fully hydrogenated cottonseed (HCO) oils, and palm stearin (PS). The first specific aim was to optimize the reaction conditions of substrates for trans-free SLs production. Second specific aim was to characterize the physical and chemical properties of SLs and compare with physical blends. Third specific aim was to characterize the textural and sensory properties of margarines prepared with selected SLs and compare with commercial brands. Desirable and optimal products composition were achieved at 50 C, 18 h, 2:1 (HSSO:SDASO) with Lipozyme TLIM, containing 15.1 mol% stearic acid and 10.5 mol% SDA. It had desirable polymorphism ('), thermal properties, and solid fat content (SFC, 3.2% at 10 C and 0.1% at 33.3 C) for formulation of soft margarine. The margarine formulated with this SL was trans-free, SDA-enriched with no significant difference in sensory properties. For the second combination, desirable SL containing 12.3 mol% stearic acid and no TFA was obtained at 50 C, 20 h, 2:1 (PS:HSSO) with Novozym 435. This SL was suitable for stick/hard margarine because of its high melting completion temperature (45.4 C). In the third combination, SL synthesized at 56 C, 6 h, 4:1 (PS:CO), using Novozym 435, was used to formulate hard/industrial margarine with high oxidative stability and no TFA. In the fourth combination, SL synthesized at 65 C, 16.5 h, 2:1 (PS:HCO) using Lipozyme TLIM, was selected to formulate margarine. A trans-free hard margarine with high melting completion temperature (50.1 C) that may be suitable for puff pastries, cooking, or baking purposes was obtained. Different types of trans-free margarines were produced, the most prominent being SDA-containing soft, spreadable margarine. This research resulted in the production of trans-free SLs as an alternative to partially hydrogenated fat and can be used by the food industry to formulate trans-free foods.