| Beef tallow is the fatty tissue of cattle using appropriate processing methods for refining to obtain edible fats and oils with rich aroma,commonly used as base oil for hot pot bases and flavor blending oil.For different brands of beef tallow,due to the different breeds and origins of cattle,as well as differences in the refinement process of beef tallow,there exist large differences in the volatile composition of different brands of beef tallow.It allows for monitoring flavor changes during the beef tallow refinement process more accurately to analyze the volatile substances of different kinds of beef tallow to find and identify key flavor substances.Traditional beef tallow has disadvantages such as high cost of refinement process and large loss of beef tallow flavor,which can be optimized by controlling the beef tallow refinement process to improve the quality while retaining the original flavor to the greatest extent.The solid state of beef tallow at room temperature is not conducive to its application in the food industry.The dry fractionation process is used to prepare fractionated beef tallow fractions with different melting points,which is cost-effective,non-polluting and full of beef tallow flavor.Therefore,in this study,the volatility of different beef tallow was first analyzed to find out the characteristic flavor components,then the beef tallow with gross tallow was refined as raw material and the refined beef tallow was fractionated.The changes of the quality and flavor components in the refining and fractionation stages were analyzed,as follows:1.The characteristic volatile flavors compounds of different commercially available beef tallowThirteen different brands of beef tallow were selected to determine oil quality indicators(physicochemical properties,fatty acid composition)as well as to analyze the volatile matter composition.The results showed that the acid value,peroxide value,iodine value and saponification value of beef tallow ranged from 0.28 to 2.55 mg/g,0.06 to 0.10 g/100 g,39.09 to 46.31 g/100 g and 178.52 to 190.74 mg/g,respectively.The unsaturated fatty acids in beef tallow were dominated by oleic acid(29.98～34.60%)and saturated fatty acids were dominated by palmitic acid(23.66～40.38%)and stearic acid(6.78～25.28%).Sixteen compounds determining the characteristic flavor were found according to the OAV of volatile flavor substances in beef tallow.Comprehensive literature and standard product olfactory determination,2-n-propylfuran gave the beef tallow a special nutty flavor,n-hexanal gave the furans gave the beef tallow a burnt and nutty flavor,valeric acid and undecanal gave the beef tallow an orange flavor,2-methylbutyric acid gave he beef tallow a unique fruit flavor,and 3-octen-2-one and propyl octane 3-Octen-2-one and propylenolactone gave the beef tallow some earthy and licorice characteristics.2.The optimization and the quality change analysis of beef tallow refinement processThe moderate refinement was carried out for raw beef tallow,including enzymatic degumming,alkaline refining and adsorption decolorization.The refinement process was optimized by using the comprehensive scores of combining beef tallow flavor and base quality as the evaluation indicator.In the meanwhile,the quality changes of the beef tallow at each stage of refining were compared.The results showed that the optimal conditions for the enzymatic degumming process were 3% water addition,100 mg/Kg enzyme addition,50 ℃,210 min and p H 5.0.The optimal conditions for the alkaline degumming process were 0.3% super alkali amount,72 ℃ alkali refining temperature,the alkali refining time of 32 min and 9.5% alkali mass fraction.The optimal conditions for the adsorption decolorization process were 3% decolorant dosage,74 ℃decolorization temperature,and the decolorization time of 27 min.The quality changes of the beef tallow refining stage were analyzed,and the basic physicochemical indicators of the acid value,iodine value and peroxide value were reduced to different degrees after refining.The fatty acid content did not change much before and after refining,and the trans fatty acid content was decreasing.Compared with the unrefined raw beef tallow,the oxidation induction time of the refined beef tallow decreased by3.37 h,the tocopherol content decreased by 40.23%,and the cholesterol content decreased by 34.09%.Comparing the composition of volatile substances before and after beef tallow refining,the main aldehyde species did not change much,and the content showed a trend of first decreasing and then increasing,indicating that moderate refinement of beef tallow had little effect on flavor.3.The dry fractionation process of beef tallow and the quality analysis of fractionated componentsFour beef tallow fractions L15,L30,S30 and S40 were obtained by the dry fractionation process using refined beef tallow as raw material,and S40 had the highest yield(44.88%).Through analyzing the quality of refined beef tallow and each fraction,it was found that the acid value of fraction L15 increased by 0.65 mg/g,the iodine value increased by 6.86 g/100 g,and the peroxide value increased by 0.02 g/100 g.The unsaturated fatty acid content of the four fractions L15,L30,S30 and S40 was increasing.The content of L15 unsaturated fatty acids was the highest(53.19%)and increased by 8.64% compared with refined beef tallow;the oxidation induction time decreased to 0.91 h;and the cholesterol content decreased by 46.33% compared with refined beef tallow.The crystalline form of beef tallow was partially transformed fromβ crystalline to β’ crystalline after fractionation,and the β’ crystalline content increased from 36.33% to 72.72%.The content and type of the main aldehydes in beef tallow fractionation remained stable during the fractionation stage,while other flavor substances such as alcohols,acids and alkanes changed after fractionation.It indicates that beef tallow fractionation does not cause loss of beef tallow flavor,and the volatile substances of different fractionation fractions have some differences.In this study,the characteristic flavor substances of beef tallow were identified and the change of beef tallow flavor in the refinement stage was controlled by moderate refinement.It is of great significance to expand the application of beef tallow in the food industry through beef tallow dry fractionation technology so as to further enhance the utilization of beef tallow.At the same time,this study aims to provide reference for flavor research in refining and deep processing of beef tallow. |
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