Hide/Show Apps

Trans yağ asitlerinin yağların mikro-yapısı ve mekanik özellikleriyle, kullanıldığı gıdaların reolojik ve duyusal özelliklerine etkisinin araştırılması

Download
2009
Mert, Behiç
Tekin, Aziz
Şahin, Kübra
Kadıoğlu, Yasemen
Physical and sensory properties of the food products, containing significant amount of fat, are closely related to the crystal network formed by the fat. Hydrogenation is a process commonly used by fat industry and it was developed to manufacture fat types with desired physical and mechanical properties. However, during this process certain fat isomers, called trans fatty acids, are formed. Trans fatty acids are known with their adverse health effects therefore, especially in the USA and many other countries there are legislations issued to restrict the use of trans fatty acids in food products. Since the formation of trans fatty acids alters the crystallization kinetics and micro-structure of fats, it significantly affects the solid fat content and rheological properties. Thus, mechanical and sensory properties of food depend on the amount trans fatty acids they contain. Main objective of this project was to investigate the relation between the trans fatty acids and physical properties of products. Cookies and emulsions were the subject of this study because it was shown by many researchers that these product types are considered to be the most significant sources of the trans fatty acids in diet. In this the project three different group of fats, having similar solid fat content but different trans fat content, were prepared. In terms of trans fat the content ranged between 0% and 56%, 0% and 44% ve 0% and 35%. Microscopic and rheological studies showed that increasing trans fat content accelerated the formation fat crystals. This in turn provided faster hardening to fat during process. It was also observed that cookie types with trans content had larger volume and more crispy structure due to the higher amount air entrapped in the dough during mixing. Emulsions prepared using fat with higher trans fat content generally had less stable structure as shown by lumisizer and particle size studies. More specifically, formation of larger crystals in high trans fat samples damaged the interface between the continuous water phase and dispersed oil phase. This 19 eventually reduced the stability of the emulsions. During this project various palm oil fraction were also used for interesterification to produce low or zero trans containing fat samples. Experiments with various combinations palm fractions showed that interesterification can be used as an efficient tool for production low trans fats suitable to be used as shortening.