| Palm oil is an ingredient in traditional infant formula that provides energy for the growth of infants.However,long-term consumption of infant formula containing palm oil may lead to inadequate intake of fatty acids and calcium problems.In addition,palm oil can also cause the growth of microorganisms associated with inflammation in the intestinal tract,hence negatively influencing the establishment of a healthy microbiota.Whereas,infant formula containing 1,3-Dioleoyl 2-palmitoyl triglyceride(OPO)can significantly improve the intake of fatty acids and calcium.Therefore,infant formula containing OPO is widely favored by milk powder production enterprises and the end consumers.In recent years,studies have shown that the intestinal microbial flora has a significant influence on the prevention or improvement of host metabolic and intestinal diseases.Consequently,studying the relationship between dietary components and the intestinal microbial flora has become a subject undergoing intense research in recent years.Therefore,the main purpose of this thesis was to building up technology suitable for the industrialization of OPO.Additionally,by exploring the relationship between OPO and overall intestinal microflora using a second-generation high-throughput sequencing technology,the study looked at the positive effects of OPO on intestinal health.Specific research contents are as follows:1.This thesis used palm oil or its related product,oleic acid(from palm kernel oil)asraw material,NS40086 lipase as catalyst,and packed bed reactor to synthesize OPO.The reactions were optimized by response surface analysis method(with four factors and three levels)and the optimum conditions(from the commercial feasibility consideration)were determined as following: iodine value is 26.0 g/100 g,substrates molar ratio is 5.5 mol/mol,reaction temperature is 59.5?,and retention time is 3.5 hours.Under this condition,the actual content of palmitic acid esterified at the sn-2 position to total content of palmitic acid and CN52 value were 56.5% and 42.2%,respectively.Finally,during two large scale experiments,an average of 9 kg OPO product(the content of palmitic acid esterified at the sn-2 position to total content of palmitic acid and CN52 value were 56.3% and 41.2%,respectively)were produced using 4 packed bed reactors in series(similar to the industrial production process)according to the optimized conditions.2.Fats with three different proportion of palmitic acid esterified at the sn-2 position were used as test oils: a)low sn-2 PA fat: the content of palmitic acid esterified at the sn-2 position was 12.1% of total palmitic acid;b)medium sn-2 PA fat: the content of sn-2 palmitic acid was 40.4%;c)high sn-2 PA fat-the content of sn-2 palmitic acid was 56.3%.Fecal fatty acid profiles,calcium concentration,microbial composition and short-chain fatty acids concentration in the fecal were measured by gas chromatography(GC),ICP-MS,16 S r RNA high-throughput sequencing technology and ion chromatograph,respectively.Dietary supplementation with high sn-2 PA fat significantly reduced total fecal contents of fatty acids soap and calcium compared with the medium or low sn-2 PA fat groups.Diet supplementation with different sn-2 PA fats did not change the entire profile of the gut microbiota community at phylum level and the differences at genera level were minimal in the three treatment groups.However,a high sn-2 PA fat diet did improve total short-chain fatty acids(SCFA)content in the feces,suggesting that high dietary sn-2 PA fat might have a beneficial effect on host intestinal health.3.The impact of OPO in combination with the polyunsaturated fatty acids DHA or ARA in the diet on lipid metabolism in the liver and fecal microbiota composition were investigated in rats fed diets containing 100% OPO,90% OPO+10% DHA oil(wt %),or 90% OPO +10% ARA oil(wt %)as the fat component of the diet,respectively.Microbial composition and SCFA concentrations in the fecal were measured by 16 S r RNA high-throughput sequencing technology and ion chromatograph,respectively.The results showed that the supplementation with OPO in combination with DHA or ARA significantly promoted the abundance of Lactobacillus in the feces at the genus level.On the other hand,the abundance of the opportunistic pathogen Desulfovibrio was significantly decreased by OPO in combination with ARA compared with the OPO group.In addition,OPO in combination with DHA or ARA significantly increased total SCFA concentration in the feces,suggesting a beneficial effect on host intestinal health.Moreover,the diets also significantly decreased the content of TAG in the liver and up-regulated the expression level of PPAR?,down-regulated the expression level of Fas and Srebp-1c,suggestion that OPO in combination with DHA or ARA have a beneficial effect on lipid metabolism.The possible mechanism of OPO in combination with DHA or ARA to reduce TAG content in the liver is thought to be as following:(1)OPO in combination with DHA or ARA promotes the growth of bacteria which are responsible for SFCA production and further increase the SFCA content.(2)Acetate and butyrate might indirectly induce the up-regulation of PPAR? target genes,and thereby increase FA oxidation.(3)Propionate is used for de novo gluconeogenesis and decreases lipogenesis via down-regulation of Fas expression.4.The impact of OPO in combination with MCT in the diet on fecal microbiota composition and the concentration of lipopolysaccharide binding protein(LBP)and IL-1? were investigated in rats fed diets containing 100% OPO as fat,90% OPO+10% MCT(wt.%),or 100% MCT oil respectively.The fecal microbial composition was assessed using 16 S r RNA high-throughput sequencing technology,LBP and IL-1? were detected by commercial available ELISA kit.The results showed that OPO in combination with 10% MCT reduced the ? diversity of rats' fecal bacteria,promoted the growth of beneficial microbes,inhibited the growth of pathogenic bacteria and reduced the concentration of IL-1? and LBP,suggesting an improvement effect on the intestinal barrier function and inhibition of intestinal inflammation.In summary,the enzymatic synthesis of OPO product will lay a foundation for the product commercialization.High-throughput sequencing technique was used to study the effects of OPO and OPO in combination with polyunsaturated fatty acids or MCT on the overall rat gut microbiota.This thesis found that OPO and OPO in combination with polyunsaturated fatty acids or MCT can increase the abundance of beneficial microbes in the intestine and reduce the abundance of potentially pathogenic microorganisms.This result provides a theoretical basis for further understanding of the impact of OPO on infant health and development. |
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