Effect of hydrogenation conditions on rheological and micro-structural properties of fats

Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Food Engineering, Turkey

Approval Date: 2011


Supervisor: BEHİÇ MERT


Hydrogenation is one of the most applied techniques in the fats and oils industry to produce wide range of hardened fats with different physical and chemical properties. Each different combination of hydrogenation conditions serves products of different rheological and micro-structural properties. Therefore, the purpose of this study is to examine the effect of different industrially available catalysts on rheological and micro-structural properties of hydrogenated fats. Three different catalysts were used at two different concentrations to hydrogenate soybean oil. Two nickel based (Nysosel 222 and SP 10) and one palladium based (Pd/Al2O3) catalyst were employed. Each oil sample was hydrogenated for 20, 40, 60, 80 and 100 minutes of time intervals, under 165 ºC temperature, 2 bar H2 pressure and 500 rpm stirring rate. Resulting hardened fat samples were analysed in terms of rheological and microstructural properties. The outcomes of rheological and micro-structural analyses had a strong resemblence with the fatty acid distributions, solid fat contents, slip melting points and iodine values of the samples. The most selective catalyst was SP10, with the products of the highest trans fatty acid concent and more solid-like; where the least selective one was Pd/A with lowest trans fatty acid content and least solid-like. Crystal number and properties, the behaviours of storage and loss moduli were in correlation with trans fatty acid content of the samples. Also the moduli had a considerable parallelity with solid fat contents.