In Vitro Digestibility Of Infant Formula With Different Degree Of Hydrolysis And Its Effect On Growth And Development Of Mouse

The annual population of newborns in China is more than 16 million every year,while the ratio of breast-feeding of newborns is decreasing.Owning to high nutritional value,infant formula milk has a huge market as a substitute for breast milk.However,about 3%newborns are allergies to cow's milk protein.After hydrolyzing,the allergic protein will be decomposed as the same as other milk protein,and the baby's allergy symptoms will go away.Nevertheless,previous studies reported that some newborns who drink hydrolyzed formula milk would become obese when they grow up.Therefore,it is critical important to carried out studies about decomposing of both protein and fat,and effects on intestinal microflora by their products during digestive process of formula milk.In this paper,an in vitro quasi-real gastrointestinal digestion model was used to mimic infant digestion.Then three kinds of different types of hydrolysed formula milk were digested by this digestioin model.Furthermore,newborn mice were feed by hydrolysed formula milk,and their growth and development,organ index,physical strength and intelligence,intestinal morphology,and intestinal microorganism were detected to explore possible caused of obesity in mice.The results were shown as follows:1.Compared with hydrolyzed samples of both partially hydrolyzed infant formulas(pHIF)and exhaustively hydrolyzed infant formulas(eHIF),the unhydrolyzed sample contained much more macromolecular proteins and much larger size of micelle,and also produced much more polypeptides after digestion.The molecular weight of the polypeptides was less than 3.5 KDa in eHIF sample,which might be the main reason to reduce the allergy.The content of allergic protein(P-lactoglobulin,casein)was about 42.36 ppb in both pHIF and eHIP during gastric digestion.Industrial hydrolysis not only accelerated the releasing rate of free fatty acids,but also increased the content of long-chain fatty acids in digested products in both pHIF and eHIP.Moreover,digesting process was much faster and product size was much smaller in these two samples.YWhile lipid droplet was aggregated,and protein and fat could not be digested completely in the unhydrolyzed sample.2.Fed on eHIF,the mouse had longer length of body and tail and heavier weight.The lower liver index and higher kidney index were detected in mice fed on both pHIF and eHIF.The villus height and crypt depth of the eHIF group were significantly higher than that of the standard group,and the crypt depth of the eHIF group were significantly higher than those of the pHIF group.But there was no significant difference of crypt depth between the pHIF and the standard group.As for the intelligence level,the total and rotational times of arm entry in pHIF group were lower than those of the standard group.The exploring ability of eHIF group was significantly higher than that of the standard group.As for the physical level,the eHIF group cost the longest time and the standard group had the shorted time during swimming.3.Compared with the standard group,both pHIF and eHIP groups had rich and closer affinity of intestinal microflora.Moreover,lower level of proteobacteria and higher firmicutes abundance were detected in hydrolyzed groups.Therefore,the hydrolyzed formula milk was digested very fast,and has more abundant polypeptide and lipid after digestion,which might be resulted from the special fat ball interface.Furthermore,the different intestinal microflora might contribute to the obesity in the hydrolyzed groups.