| Vitamin is one of the basic nutrients of human body,among which folic acid can be used as a carbon unit carrier,which can prevent neurological defects in infants.α-tocopherol has antioxidant activity and is of great significance in preventing and delaying oxidative stressrelated diseases.However,they are limited in food applications because of their low solubility and poor stability.Therefore,the development and design of suitable edible carrier and its application in functional food become the focus of attention.Protein particles are potential coencapsulation carriers.The co-encapsulation of different vitamins is beneficial to the development of functional foods with various health functions.Whey protein isolate(WPI)and lysozyme have the advantages of rich nutritional value and biosafety,and are often used for the inclusion,protection and delivery of active ingredients.In this paper,the coencapsulation of folic acid and α-tocopherol by lysozyme and the delivery of lysozyme DNA nanoparticles were studied.Folic acid and α-tocopherol were co-encapsulation in WPI and used in fortified bread.The results provide theoretical basis for the development and design of new functional food carrier materials.The main research contents are as follows:1.Construction of lysozyme-folic acid/α-tocopherol and lysozyme-folic acid/α-tocopherol-DNA nanoparticles.First,the encapsulation of folic acid and α-tocopherol by lysozyme was studied,and the difference of the encapsulation efficiency between single encapsulation and co-encapsulation of the two vitamins was analyzed.Folic acid concentrations of 20-60 μg/m L and α-tocopherol concentrations of 30-80 μg/m L were selected.For single-encapsulation systems,the encapsulation efficiency of folic acid or α-tocopherol increased with the increase of the concentration.In the co-encapsulation system,low concentration of α-tocopherol can improve the encapsulation efficiency of folic acid,but folic acid does not affect the encapsulation efficiency of α-tocopherol.The results of antioxidant activity assay showed that lysozyme encapsulation protected folic acid and α-tocopherol from free radical attack to some extent.In order to improve the stability of the system,the interaction between lysozyme and DNA was further investigated.The system showed good physical stability by encapsulation folic acid and α-tocopherol in lysozyme DNA complex.Finally,in vitro release and bioaccessibility of folic acid and α-tocopherol from lysozyme and lysozyme DNA nanoparticles were studied.The bioaccessibility of coencapsulation folic acid was higher than that of single-encapsulation folic acid,which was similar to free folic acid.The bioaccessibility of co-encapsulation α-tocopherol was significantly higher than that of the single-encapsulation and free types.2.Preparation of fortified bread with folic acid or α-tocopherol based on WPI encapsulation.Firstly,the effects of WPI on folic acid and α-tocopherol encapsulation efficiency,particle size and ζ-potential were investigated.Folic acid concentrations of 20-60 μg/m L and α-tocopherol concentrations of 30-80 μg/m L were selected.The results showed that the encapsulation efficiency of folic acid/α-tocopherol increased with the increase of folic acid/α-tocopherol concentration.Finally,a co-encapsulation system with folic acid concentration of60 μg/m L and α-tocopherol concentration of 80μg/m L was selected for the preparation of fortified wheat bread and sourdough bread.WPI did not affect the stability of folic acid during baking,but effectively improved the stability of α-tocopherol during baking.The folic acid retention rate of wheat bread was significantly higher than that of sourdough bread,but α-tocopherol was not affected by bread types.The specific volume and texture results showed that folic acid,α-tocopherol and WPI-folic acid-α-tocopherol mixture increased the hardness of bread.The storage results showed that folic acid,α-tocopherol and WPI-folic acid-α-tocopherol mixture had no significant effect on the aging rate of bread.During bread storage,the retention rates of folic acid and α-tocopherol decreased slightly,and the stability of folic acid and α-tocopherol in sourdough bread was lower than that in wheat bread. |
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