| Sorbic acid is a preservative with weak antioxidant properties and is widely used in food processing such as baking.Its application performance will be affected by the parameters of food processing,and the synergistic effect of sorbic acid and other additives in food also needs to be further studied.In addition,since most of the preservatives in the dough,such as sodium dehydroacetate,calcium propionate and sorbic acid,will reduce the yeast activity while preserving,and it will soon be limited to use sodium dehydroacetate in flour products in our country,so it is necessary to develop preservatives that do not reduce yeast activity during dough preparation,while maintaining good preservative effects on bakery products.Therefore,in this paper,taking sorbic acid as the research object,its the antimicrobial properties were studied,and the effect of p H value on the antimicrobial activity of sorbic acid was explored.The antimicrobial effect of sorbic acid in combination with other antimicrobial agents was investigated.At the same time,the antioxidant properties of sorbic acid were studied.The effects of p H,temperature and other factors on the antioxidant properties of sorbic acid were investigated respectively,and the antioxidant activity of sorbic acid combined with vitamin C was explored.Further,taking the slow release of preservatives as the antiseptic solution in bakery food processing,the morphology,thermal properties and antiseptic properties of microencapsulated sorbic acid on bread were studied,and its influence on the activity of baker’s yeast and its application in bakery products were investigated.The main research contents and results are as follows:1.The antimicrobial activity of sorbic acid and the effect of p H value on its antibacterial activity were explored.Sorbic acid had an inhibitory effect on the tested bacteria and mold,and among them,the inhibitory effect on mold was more excellent.The inhibitory effect of sorbic acid on four bacteria(E.coli,K.pneumoniae,S.aureus and B.cereus)(Minimum inhibitory concentration was 1250 μg/m L.)was comparable to that of benzoic acid,better than that of potassium sorbate and calcium propionate.The inhibitory effect of sorbic acid on two molds(A.niger and A.flavus)(Minimum inhibitory concentration was 156 μg/m L.)was superior to benzoic acid,potassium sorbate and calcium propionate.The minimum inhibitory concentration of sorbic acid against the above four bacteria and two molds increased with the increase of p H,indicating that sorbic acid had better bacteriostatic effect in acidic environment.The results of combined antimicrobial experiments showed that when sorbic acid was used in combination with tetracycline hydrochloride,chloramphenicol,benzoic acid,calcium propionate and stevia polyphenol respectively,the inhibitory effects on microorganism were irrelevant.When sorbic acid was used in combination with benzoic acid and calcium propionate respectively for mold,the inhibitory effect on mold was irrelevant.2.The antioxidant activity of sorbic acid and the effects of p H,temperature and other factors on the antioxidant properties of sorbic acid were explored.In the aqueous system,the DPPH and ABTS radical scavenging abilities of sorbic acid and potassium sorbate were similar,but the ability to reduce iron ions was weak.The ORAC value of sorbic acid was1823.11 ± 163.29 μmol TE/g.The antioxidant capacity of sorbic acid in the oil phase was better than that of α-tocopherol.The antioxidant activity of sorbic acid was stable in the p H range of 3-5.At 25oC-85oC,the DPPH free radical scavenging rate of sorbic acid was less affected by temperature changes(always maintained below 40%),which was related to the excellent thermal stability of sorbic acid.When sorbic acid was used in combination with VC,the DPPH radical scavenging activity exhibited by the combination of sorbic acid at 0.001mg/m L and VC at 0.010 mg/m L was additive.Under other concentration conditions,the interaction index of sorbic acid and VC was less than one(γ<1)when used in combination,indicating that under the test concentration ratio,the antioxidant activity of sorbic acid combined with VC was an antagonism effect.3.The physicochemical properties of microcapsulated sorbic acid were explored.Taking microcapsulated sorbic acid SA70(sorbic acid content of 70%)as an example,the observation results of super depth 3D microscope and polarizing microscope with hot stage indicated that microencapsulated sorbic acid SA70 was uniformly wrapped.XRD analysis showed that the core material sorbic acid and the wall material did not form a eutectic in SA70.The particle size of SA70 was mainly in the range of 200 μm-1300 μm,narrower than that of sorbic acid,which was conducive to the controlled release of the product.The acid value results proved that sorbic acid was successfully encapsulated,and the encapsulation rate was close to the theoretical value(70%).The SA70 wall melted at 50oC-70oC and the inner core melted at 125oC-140oC.During dough fermentation,the walls of SA70 did not melt and sorbic acid was exposed to the dough.Therefore,microencapsulated sorbic acid could be used in bakery products.4.During dough fermentation,the addition of SA70(0.3%)increased the yeast activity,while sodium dehydroacetate,calcium propionate,potassium sorbate and unembedded sorbic acid all inhibited the yeast activity under the same conditions.Microencapsulated sorbic acid SA70 was further added to the bread.The texture analysis of bread showed that the bread with SA70 had moderate hardness and chew resistance,and had higher elasticity,which was better than bread with other food preservatives.The overall sensory score of bread added with SA70 was high,and it was more popular with tasters.Under the environment of 25oC and 90%relative humidity,after adding SA70 or SA85,the shelf life of bread and cakes could be extended up to 9.0 d and 5.5 d respectively.Among them,the ability of microencapsulated sorbic acid SA85 and SA70 to prolong the shelf life of bread and cakes was better than that of sodium dehydroacetate,calcium propionate and unencapsulated sorbic acid. |
PDF Full Text Request