Related Research On Breast Milk Composition

Part I Peptidome analysis of breast milk in mothers of very low birth weight infants during different periodsObjective: By comparing and analyzing the differences between colostrum,transitional milk and mature milk peptides from mothers of very low birth weight infants,the potential biological functions of breast milk peptides were screened.Method: Taking advantage of established breast milk bank,we collected colostrum,transitional milk and mature milk samples from very-low-birth-weight infants' mothers who were hospitalized in the Department of Neonatology at the Maternity Hospital of Nanjing Medical University during December 2016 to February 2017.Two samples of colostrum,transitional milk,and mature milk were randomly selected from each sample.Each sample was consisted by a mixture of three different mothers' breastmilk during the different period.A liquid chromatography tandem mass spectrometry technique was used to construct a peptidomics analysis of breast milk at different time periods.Since the bioactive components in colostrum are much more abundant than that in transitional milk and mature milk,peptide with a difference of more than 2 fold and a statistically significant difference(P<0.05)between colostrum and other milk were screened.The basic biological information of these differential peptides was analyzed through databases such as Uniprot and Swiss Prot.IPA software and the KEGG database were used to make preliminary predictions of the biological functions that differential peptides might play.Result: We identified and quantified 3182 non-redundant peptides in total from 6 samples.There were 280 peptides with a differential expression fold greater than 2 fold,including 144 up-regulated peptides and 136 down-regulated peptides,among which 30 were derived from the precursor protein Beta-casein.Derived from the precursor protein Beta-casein,including 22 up-regulated peptides and 8 down-regulated peptides.The isoelectric point and molecular weight analysis of the differentially expressed peptides basically conformed to the range identified by mass spectrometry.GO analysis and Pathway analysis showed that these differentially expressed peptides enriched in a variety of biological processes,including brain and nerve development and anti-virus functions.We focused on the Beta-casein,a precursor protein that produces the most differentially expressed peptides,and it was found that the peptide sequence is very similar to many functional peptides.Conclusion: The polypeptide expression profiles of breast milk at different time points were significantly different,among which multiple differentially expressed peptides derived from Beta-casein may have biological activities such as immunoregulation,antibacterial and antioxidation.Part II Effects of various processes and lactation time on macronutrients in breast milkObjective: Effects of Holder pasteurization,temperature and duration of frozen,speed of continuous breast milk pumping,duration of continuous breast milk pumping and types of pumping tube on macronutrients and total energy of breast milk and to analyze the circadian variation of macronutrients and energy content of breast milk.Methods: Two hundred and forty-two breast milk samples were collected from healthy mothers of 228 infants who were hospitalized in Obstetrics and Gynecology Hospital Affiliated to Nanjing Medical University from April 2016 and December 2016.Fat,protein,carbohydrate and energy contents of the breast milk samples were detected before and after various processes to analyze whether they were influenced by Holder pasteurization,frozen storage conditions(temperature and time),duration of continuous pumping and types of pumping tube and to observe the variations within a single day.Paired t-test,repeated-measures analysis of variance,one-way analysis of variance and LSD-t test were used for statistical analysis.Results: The contents of fat,protein and energy in breast milk were significantly decreased [(3.69±0.98)vs(4.22±1.00)g/dl,t=9.405;(2.12±0.34)vs(2.21±0.34)g/dl,t=4.785;(69.77±9.35)vs(74.94±9.53)kcal/dl(1kcal=4.184 k J),t=9.470],while the carbohydrate was increased[(6.66±0.17)vs(6.62±0.17)g/dl,t=–3.442] after Holder pasteurization comparing with those before(All P?0.01).Breast milk frozen at – 80 ? had higher protein content than that frozen at – 20 ?(P-temperature?0.05).Breast milk stored at – 20 ? for 15,30 and 60 days were significantly increased(LSD-t test,P?0.05)and that kept for 90 days were lower than those at 30 and 60 days. Compared with fresh breast milk,breast milk stored at – 80 ? showed significantly decreased fat,protein and energy contents at 60 and 90 days,but increased carbohydrate content at 60 days(LSD-t test,P?0.05).There were no significant differences between macronutrients in breast milk pumping at 5 ml/h,10ml/h or 15ml/h(P-speed?0.05).Compared with fresh breast milk,breast milk which was pumped at 1,2 or 3 h through gastric tube(size 6,8 or 10)or transfusion connecting pipe had lower fat content(LSD-t test,P?0.05).Compared with fresh breast milk,breast milk had lower energy content on condition that it was pumped through gastric tube size 6 at 2 or 3 h or through gastric tube size 8 or 10 or transfusion connecting pipe at 1,2 or 3 h(LSD-t test,P?0.05).Breast milk secreted from 12:01 to 15:00 had higher fat and energy contents[(5.16±0.93)g/dl and(86.96±9.35)kcal/dl] than that secreted from 00:01 to 03:00[(4.54±0.75)g/dl and(80.77±7.75)kcal/dl],from 03:01 to 06:00[(4.61±0.75)g/dl and(81.44±7.69)kcal/dl] or from 21:01 to 24:00[(4.71±0.88)g/dl and(82.44±8.82)kcal/dl].Breast milk secreted from 09:01 to 12:00 had higher fat contents[(5.01±0.94)g/dl] than that secreted from 00:01 to 03:00 and 03:01 to 06:00.Moreover,Breast milk secreted from 09:01 to 12:00 had higher energy contents [(85.31±9.62)kcal/dl] than that secreted from 00:01 to 03:00(LSD-t test,P?0.05).Conclusions Fresh breast milk,especially from the baby's biological mother,is better than processed milk to meet the infantile need for growth and development.