Study On The Transformation And Enrichment Of Folate In Eggs And Its Processing Stability

Folate,an essential B vitamin,is involved in the synthesis of protein,nucleic acid and other important substances in the body.Lack of folate can cause diseases such as anemia and developmental delay,and lack of folate in pregnant women can lead to the occurrence of neural tube defects in babies.Humans cannot synthesize folate by themselves and have to gain it from foods.In natural foods,folate is mainly in the form of polyglutamic acid,which has a poor stability and bioavailability?about 50%?.Producing folate-enriched eggs by laying hens through the way of biological enrichment has become a new way to obtain naturally safe and highly bioavailable folate.Laying hens can absorb and metabolize folic acid from feed,and convert it to egg yolk.During the metabolic process,the synthetic folic acid will be converted into5-methyltetrahydrofolate?5-MTHF?monoglutamic acid form,which has a high bioavailability of 100%.In addition,eggs have high nutritional value,so eggs can be used as an ideal source of folate supplementation.However,since 5-MTHF is sensitive to environmental factors such as light,heat and oxygen,it is prone to degradation during the processing,which hinders the industrial production and application of folate-enriched egg products.Therefore,the production of eggs rich in 5-MTHF by the way of biological enrichment,the enrichment law 5-MTHF in eggs,and the stability of 5-MTHF during the processing and storage of egg yolk powder were studied in this paper.Main contents and conclusions of this paper are as follows:The effects of dietary FA on the enrichment of 5-MTHF in eggs were studied.Results showed that there was a dose-response relation between 5-MTHF content in eggs and dietary FA content,with the highest content of 5-MTHF in eggs reaching67.47?g/egg?based on the edible portion of 58.8 g per egg,114.74?g/100 g edible portion?at week 4 which was 1.93 times as high as that in control group.In addition,no significant difference was observed in egg quality and laying performance due to the added folic acid in basal diet.The effects of dietary supplementation of VB₁₂ or V_C on the enrichment of 5-MTHF in eggs were studied.Results showed that the high addition of VB₁₂?100?g/kg feed?decreased 5-MTHF content in eggs?down by 8.80%compared with the control group?at week 6 and the egg weight decreased too.And the addition of V_C?150 mg/kg feed?improved 5-MTHF content in eggs,with the highest content reaching 77.93?g/egg?based on the edible portion of 58.8 g per egg,132.53?g/100 g edible portion?at week 6?up by 11.94%compared with the control group?.Therefore,V_C could promote the enrichment of 5-MTHF in eggs.The distribution and storage stability of5-MTHF in eggs were invesitigated.It was shown that 5-MTHF was mainly located in egg yolk granule and accounted for 84.78%in the total folate of eggs rich in 5-MTHF.Also,5-MTHF in eggs remained stable during 35-day storage.Lastly,the stability of 5-MTHF in the processing of egg yolk powder rich in 5-MTHF were investigated.Results showed that 5-MTHF was sensitive to oxygen compared with light and heat,and the addition of antioxidant improved the stability of5-MTHF during the processing of eggs.In the process of pasteurization,the retention rate of 5-MTHF in the blank group was 74.96%.And the addition of V_C?0.2%,w/v?increased the retention rate of 5-MTHF to 87.76%in egg yolk while the same addition of V_E?0.2%,w/v?increased the retention rate of 5-MTHF to 94.16%.In the process of spray-drying,the retention rate of 5-MTHF in the blank group was 61.70%.And the addition of V_C?0.2%,w/v?increased the retention rate of 5-MTHF to 84.80%while the same addition of V_E increased the retention rate of 5-MTHF to 92.69%.Compared with normal spray-drying,the egg yolk powder by nitrogen spray-drying was better in solubility and emulsification.Furthermore,nitrogen-filled packaging also improved the stability of 5-MTHF in egg yolk.