Enzymatic Preparation And Functional Study Of Human Milk Fat Substitutes

Human milk fat(HMF)is the ideal food for the growth and development of infants.HMF is one of the main nutrients in human milk.The spatial distribution of triglyceride fatty acids is characterized by the distribution of saturated fatty acids(palmitic acid)mainly in Sn-2,but not saturated Fatty acids(oleic acid and linoleic acid)are mainly distributed in the Sn-3 position.At present,the fat composition of infant formula in the market is mainly composed of ruminant milk fat and vegetable oil physical blending.The total fatty acid composition is similar to that of human milk fat,but the spatial distribution structure of fatty acids is significantly different from that of human milk fat.This different will effect the absorption of calcium and energy.In this paper,the enzymatic preparation of human milk fat substitutes(HMFS)and its functional study in vivo were studied.Lipase RM IM as immobilized lipase was chosen as the catalyst to prepare lard and homemade fatty acid methyl ester as the raw material for transesterification HMFS,and the product of molecular distillation deacidification purification was studied,on this basis,the animal experiments to study its functionality was studied.The main findings are as follows:(1)The Preparation of HMFS from lard fat and fatty acid methyl ester of camellia seed oil by Lipozyme RM IM.First,the camellia oil fatty acid methyl ester was prepared from camellia oil and methanol with the mass ratio of alcohol to oil of 6:1 and KOH as the catalyst.The lard fat and methyl oleate oil were selected as raw materials and catalyzed by lipase Lipozyme RM IM Transesterification and response surface design to obtain the optimal process parameters,the temperature 55 ?,the substrate mass ratio 1.6:1,the amount of enzyme 6.5%,the reaction time 6h,under these conditions,the resulting triglyceride Sn-2 position C16:0 average relative content was 69.98%.The average content of C18:1 in total fatty acid composition was 39.87%,of which only 16.82%was on Sn-2,which was in good agreement with the theoretical value.After immobilized lipase Lipozyme RM IM using 10 times,the enzyme activity still retains 87.63%,The stability of Lipozyme RM IM is better.(2)The deacidification purification of the crude product of enzymatic transesterification HMFS by molecular distillation was studied.The HMFS acid value was the indicator,the response surface design to obtain the optimal process parameters:temperature 209?,speed 180 r/min,feed rate 2mL/min,under these conditions,the resulting HMFS acid value 0.036 mg/gKOH.The rate was 49.19%with a purity of 87.64%.The physicochemical properties of the HMFS were tested in accordance with GB11765-2003 and SC/T 3502-2000,and the Loewene color is 8.4(yellow value 5.8(red value),the melting point is 20.95? lower than that of the raw material which means C18:1 of camellia seed oil has been incorporated into HMFS.The storage stability test of HMFS found that,adding natural antioxidant?-carotene would increas the storage stability of HMFS.(3)The function of HMFS was evaluated by animal experiments.Male SD rats were used as animal models to study the apparent digestibility of fat.The results showed that the contents of palmitic acid in the small intestine of HMFS rats decreased significantly,and HMFS promoted the absorption of palmitic acid to a certain degree.SD rats fed for 30 days to evaluate HMFS in vivo metabolism,the results showed that HMFS group apparent increase in apparent fat digestibility,the excretion of C16:0 and fat,serum metabolic indicators analysis showed that HMFS intake can promote low density lipoprotein in serum and triglyceride levels.The stool calcium content of different doses of HMFS group were significantly reduced,indicating that HMFS intake reduced the formation of calcium soap.The analysis of short-chain fatty acids in the small intestine and faeces showed that the HMFS increased the short-chain fatty acids of intestinal,promoted the digestion and absorption of nutrients,and ultimately manifested as promoting feed intake and the increase of body mass.The intake of HMFS is beneficial to the gut health in rats.