Study On Fat Characteristics Of Lanzhou Fat Tail Sheep And Preparation Technology Of Sterol Esters

Lanzhou fat tail sheep has a large amount of fat deposited in the tail,which is a famous long-tailed local sheep breed in China.In 2006,Lanzhou Fat tail Sheep was a national-level protected species of livestock and poultry genetic resources with an extinction frequency of 0.77.The failure to make rational use of a large amount of fat deposited in the tail is one of the bottlenecks restricting the protection of the germplasm resources of the Lanzhou fat tail.The experiment used Lanzhou fat tail fat as the research object,and tested several physical and chemical indexes such as melting point,iodine value,saponification value and acid value.The composition and content of fatty acids in tail fat were determined by gas chromatography?GC?;Fatty acid methyl esters of the tail are transesterified with phytosterols to form aliphatic sterol esters,and separation and purification of polyunsaturated fatty acids in fat tail of Lanzhou fat tail sheep by urea adduction method.The research results can provide reference and technical route for the development and utilization of tail fat.The main results are as follows:?1?study on fat characteristics of Lanzhou fat tailed sheepThe melting point of the tail fat is 47?,the iodine value is 64.5 g I₂/100g,the acid value is 0.116 mg KOH/g,the saponification value is 195.14 mg KOH/g,and 36fatty acids are detected in the tail fat.It accounts for 99.75%of the total fatty acids,of which the unsaturated fatty acid content is 56.68%,the oleic acid content is the largest,which is 41.18%,and the saturated fatty acid content is 43.31%.It mainly contains palmitic acid and stearic acid,and the content is 20.64%and 11.37%.The polyunsaturated fatty acid content was 6.08%and the conjugated linoleic acid?CLA?content was 1.15%.?2?Lanzhou fat tailed sheep tail fat separation polyunsaturated fatty acidSelecting urea adduction method to separate polyunsaturated fatty acids from Lanzhou fat tail sheep.The single-factor test was used to determine the separation and purification of polyunsaturated fatty acids by reflux temperature,fatty acid/urea?W/W?ratio,methanol/urea?V/W?Specific effects of factors including inclusion reaction temperature and inclusion reaction time.Based on the purity of polyunsaturated fatty acids in the product,the key factors were screened on the basis of single factor experiments and orthogonal experiments were performed.The optimum reaction conditions were:reflux temperature 55?,fatty acid urea?W/W?ratio of 0.4,methanol/urea?V/W?ratio of 2,inclusion temperature-10?,inclusion time of 15 hours.The purity of the polyunsaturated fatty acid in the product was82.71%.?3?study on preparation of aliphatic sterol ester compounds by using Lanzhou fat tailed sheepEthyl palmitate was used instead of the mixed fatty acid methyl ester to transesterify with sterol,and four main factors affecting the transesterification reaction were selected:reaction molar ratio of fatty acid methyl ester to phytosterol,catalyst ratio,transesterification temperature and transesterification time.After single factor experiment and stepwise optimization of the experimental conditions,the optimal conditions were determined by the esterification rate of sterol:the molar ratio of decyl alcohol to methyl palmitate was 1:1,the transesterification temperature was210?,and the catalyst ratio was 5%.The exchange time was 7 hours,and the sterol esterification rate was 92.17%.The tail fat of Lanzhou fat tail sheep was extracted and saponified and methylated.The conditions affecting the transesterification reaction were optimized according to the results of single fatty acid transesterification,and the transesterification reaction of mixed fatty acid methyl ester with phytosterol was carried out.The optimum conditions were determined to be a molar ratio of decyl alcohol to mixed fatty acid methyl ester of 1:1.2,a transesterification temperature of 210?,a catalyst ratio of 5%,a transesterification time of 7 hours,and a final sterol esterification rate of 80.53%.The experiment concluded that Lanzhou fat tail sheep tail fat has high content of unsaturated fatty acids and high polyunsaturated fatty acid content.As one of the raw materials for the formation of sterol esters,tail fat has a higher esterification rate;the polyunsaturated fatty acid methyl ester is separated by urea encapsulation,and the purity of the product is high,and both methods can be used.