The Effects Of Light And Heat On Infant Formula Studied By Spectroscopy

Infant formula is the main source of nutrition for non-breastfed infants,and its nutritional value is directly related to the life and health of infants.However,during the production,transportation,storage,and brewing of milk powder,the base material of milk powder is susceptible to changes and interactions,especially affected by light and heat,and its quality is easily affected.In this subject,The conditions of light and heat in the environment of infant formula are changed,and the impact of light and heat on the quality of infant formula is analyzed from different research perspectives:(1)Steady-state fluorescence spectra and time-resolved fluorescence spectra of three different stages of infant formula milk powder(stage?,stage?,and stage?)under different colors(red,green and blue)were studied.The results showed that the effects of different colored light on infant formula were different,and their order of influence was: blue light> green light> red light.In addition,infant formula at different stages will be affected by varying degrees of light,with the greatest impact on stage III infant formula and the least impact on stage I infant formula.(2)The effects of different blue light intensities on the steady-state and timeresolved fluorescence spectra of infant formula milk powder were studied.The results showed that the stability of VB2 in infant formula is inversely proportional to the intensity of blue light,that is,the stronger the light intensity,the more unstable VB2 in infant formula.But the effect of light intensity change on the stability of VB2 is lower than that of color light change on the stability of VB2.(3)Fluorescence spectra of infant formula milk powder(stage?,stage?,and stage ?)at different temperatures were studied.With the gradual increase in temperature,the maximum fluorescence intensity of the three-stage infant formula and casein decreased,and the fluorescence emission peaks blue shifted.Among them,the maximum fluorescence intensity of infant formula was different from that of casein.However,the decrease in fluorescence intensity of infant formulas in stage?and?is significantly different from that in infant formulas in stage ?.As far as the blue shift of the peak position is concerned,the blue shift of the casein peak position is lesser than the blue shift of infant formula,and the blue shift of infant formula is the bigger.This shows that the protein in the three-stage infant formula is not only casein,but also a part of whey protein,and the protein composition in the three-stage infant formula is different,of which the stage?infant formula protein is most sensitive to temperature changes.The fluorescence lifetimes of three infant formulas and casein at different temperatures were measured.After double exponential fitting of their lifetime curves,it was found that they both had two lifetimes.Tryptophan and phenylalanine are the two possible sources of lifespan,and their fluorescence lifespan gradually decreases with increasing temperature.After being heated to 95 ° C and then cooled to 20 ° C,the fluorescence intensity and lifetime of the three-stage infant formula and casein were restored,indicating that some structural changes of casein were reversible after returning to room temperature at high temperatures.(4)Mid-infrared spectroscopy of infant formula milk powder(Section ?,Section ?,Section ?)at different temperatures was studied.Mid-infrared spectra of infant formula milk powder at different stages are measured at intervals of 5 ? in the temperature range of 20 ?-95 ?,Based on the changes in the protein's characteristic absorption peaks in the original spectrum at different temperatures,speculate the changes in the protein in the sample.The results show that: In the three groups of samples,the characteristic absorption peaks of the protein nicotinamide I band and the protein nicotinamide II band showed the same trend.The second derivative of the original spectrum of the sample was used to analyze the type of secondary structure and the relative content of various secondary structures in the protein component of the sample,and the change with temperature has analyzed.The results show that the protein in infant formula contains ? –Helix,?-sheet,?-turn and random coil four secondary structures,the content of each secondary structure in different samples,different temperatures are significantly different.In addition,there is a certain mutual conversion between ?-sheet,?-turn,?-helix and random curl,and this conversion is reversible.