The Research Of Several Commercial Infant Milk Powder Quality Stability

As a substitute of breast milk,infant formula milk powder is important nutrition for infants' healthy growth.But the quality of infant formula in the processing and storaging can easily be affected by the external environment.The infant formula is vulnerable to agglomerate,deliquescence.The amount of fat,vitamins and other nutrients of infant formula in the storage process can cause fat oxidation,non enzymatic browning and vitamin degradation reaction and so on.The fat oxidation,vitamin degradation in the storage process of milk powder had been researched.However,few researchers focus on the unsealing infant formula's physical and chemical properties.Unsealing infant milk powder can be influenced by storage environment easily.Winter temperature in our country can be low below 0?,and the summer temperature can be up to 37?.The research for sold infant formula quality after opening packet is very necessary.On the other hand,inferior milk powder event and other malignant events letted Chinese people to prefer importing milk powder to domestic milk.Therefore,in this paper,the unsealing and sealed storage,domestic brand and foreign brand of milk powder were picked to storage under 4?,18? and 37? for 90 d,the nutrition and quality stability were studied.The results were as follows:Most of the fatty acids decreased with storage time passing.And them reduced more when storaging at 37? than at 4?.Free fatty acid content increased with time passing.At 37?,propylene glycol content increased with time passing,but propylene glycol content did not change significantly at 4?.In the storage of unsealing infant formula,glass transition temperature increased with storage time extension.Lactose content and vitamin C content decreased as the storage time prolonged and the temperature rose.Fat hydrolysis,oxidation,lactose and vitamin C oxidation would be happened in unsealing infant powder storage.And keeping at low temperature could delay those oxidation reactions.Based on propylene glycol content,domestic brand milk powder B's fat stability was not as good as the foreign brand Y's.But based on fatty acids and free fatty acids,there was no big difference between two brands.Foreign brand Y contained more lactose than domestic brand B,but lost faster during storage.The non enzymatic browning products of two brands were little,and didn't change much.Almost all the fatty acids were moderate negative correlated with propylene glycol,the correlation coefficient ranged of-0.527 to-0.814.The increasing of propylene glycol was a combination of saturated fatty acids' and unsaturated fatty acids' oxidation reactions.Lactose content and vitamin C content could affect the glass transition temperature and were highly negative correlated with the glass transition temperature.In the dry storage condition(about 10% humidity),infant milk powder sealed storage could guarantee the basic nutrients,such as the stability of the fat,vitamin C,but could not influence the lactose,the maillard reaction and the senses analysis.