The Study On Quality Defects And Improvement Of Beef Tallow-based Shortening

Traditionally edible beef tallow is widely used in the baking industry because of enhanced aroma and flavor of food products. However, beef tallow-based shortening is easy to undergo sandiness or graininess which leads to bad physical properties when temperature fluctuates during handling, storage and transportation. This paper is aimed to compared and discuss the essential reasons of the graininess crystals in beef tallow shortening and solve the graininess by modificated formulation.Firstly, the difference of slip melting, fatty acids , triacylglycerols (TAGs) ,polymorphism, DSC melting curves and morphology of the grainy crystals and surrounding materials in the bad beef tallow-based shortening were studied. TAGs results showed that the contents of polyunsaturated TAGs (POL, POO and SOO /SSL) of grainy crystals decreased markedly compared with their surrounding materials while the contents of symmetrical monounsaturated TAGs (POP, POS and SOS) rose in the graininess. The results of X-ray diffraction (XRD) showed that there were someβform grainy crystals exceptβ′form. The melting curves of grainy (DSC) certified the existence of complex polymorphism. The morphology of grainy crystals is coarser than that of surrounding materials. It can be confirmed that low melting point TAGs will melt with rising temperature, which would provide enough spaces for the symmetrical monounsaturated TAGs to move and form the crystal nuclei. Symmetrical TAGs(POP、POS、SOS)agglomerates and form the bigger and sheetβpolymorph.The crystal agglomerates form the bigger crystal clusters and result in the graininess crystal in shortening. These results showed that monounsaturated TAGs were the key factor for the formation of granular crystals in shortening.Interesterification and blending were used to modify natural oil to obtain the desired tallow-based shortening. Beef tallow (BT) and low erucic acid rapeseed oil (LERSO) at different rate by chemical interesterification was studied to solve the graininess in beef tallow shortening. The results of interesterification showed that the amount of high melting point TAGs (POP、POS、SOS) of the blends of BT and LERSO(80:20 w/w) reduced greatest in following reaction conditions: the addition of methanol sodium was 0.6%(w/w) for 90mins at reaction temperature 60℃.The chemical interesterification products have the stableβ′form and the morphology of crystals appeared less densely packed. The SFC profile of chemical interesterification products was satisfied for the solid shortening stock. The binary and ternary phase behaviors of mixtures of BT with palm kernel oil (PKO), hydrogenated palm oil (HPO), palm oil (PO), palm olein (POo) and LERSO were studied using isosolid diagrams respectively. Both BT/palm oil-based fat and BT/LERSO binaries displayed good compatibility while addition of PKO would increase eutectic behavior whatever in binaries or ternaries. It was found that when the content of BT was predominant, ternary mixtures have good compatibility. The addition of BT would make up the defects of single base oil and improve the plastic property of shortening. The appropriate formulation of BT-based shortening based on the studies of ternary phase behaviors and polymorphism was following: the blends of BT and LERSO and PO as 0.8:0.1:0.1.Distill monostearate, Span 60 and lecithin was optimized as single and compound emulsifiers respectively. The formulation of base oil and emulsifiers were optimized as follows: (1) the blends of BT and LERSO(80:20 w/w) by chemical interesterification at the following conditions: reaction temperature at 60℃, methanol sodium 0.6%(w/w) for 90min, the ratio of distill monostearate, Span 60 and lecithin was 0.1:0.45:0.45 and the total addition was 1%; (2) the ratio of BT, LERSO and PO was 0.8:0.1:0.1 and mixed distill monostearate, Span 60 and lecithin was 0.8:0.1:0.1, the addition was 1%. Shortening according to this formulation prepared in the laboratory was saved in winter ( temperature range 5～15℃) for two and half months and there was no visible grainy crystals existing in the product. Baking products has the similar sense evaluation using the prepared shortening product compared with commercial shortening obtained from market in baking.