Research On Antioxidant And Quality Preserving Packaging Of Rice Wafer

Rice wafer is a kind of multi-layer biscuit made with rice flour as the raw material.It tastes crispy and also has a unique flavor of rice products.It is a product with great market prospect.Compared with ordinary biscuits without adding rice flour,rice wafer is easier to oxidize,which leads to a short shelf life and seriously affects the circulation and commercial benefits.Therefore,it is meaningful to study the antioxidant packaging of rice-wafer.In this paper,the shelf life prediction model of rice-wafer was established.Then,a kind of natural antioxidant lemon essential oil was selected.On this basis,lemon essential oil microcapsule and its active packaging film were prepared,and the influence of packaging film on rice-wafer was researched.The main results are as follows:(1)Study on the shelf life prediction model of rice wafer.Storage experiments were carried out on rice-wafer under four oxygen concentrations and three temperature conditions to measure the changes of POV,chromatic aberration and sensory indexes,and a shelf life prediction model was established according to POV.The results showed that the higher the concentration of oxygen,the faster the growth of POV.The color difference was not significant.Vacuum and high temperature had the most obvious influence on the sensory indicators of the product.According to the POV limit of products,the shelf life of packaging is predicted to be 107 days under the condition of air in the package at 23?.(2)Study on the selection and properties of natural antioxidants.Through the comparison and analysis of the antioxidant and heat-resistant properties of the two natural antioxidants,lemon essential oil was selected as the antioxidant.A storage experiment was designed to verify the antioxidant properties of the essential oil for the product.The results showed that lemon essential oil had better antioxidant properties than limonene,with a DPPH clearance rate of up to 94.73%,and a slightly better temperature tolerance below90?.Under the condition of 23?and RH 50%,the volatilization rule of lemon essential oil was nearly linear,and the volatilization rate was about 1.31 mg/(h·cm~2).(3)Preparation process optimization and performance detection of lemon essential oil microcapsule.The preparation process of microcapsules was optimized by single factor and orthogonal experiment.The morphology and thermal stability of the microcapsules were measured.The effects of different temperature and humidity on the release rate of essential oil in microcapsules were discussed.The single-factor experiment results showed that the optimal preparation conditions were 10%core-wall,40?,4 h.Taking orthogonal results and the actual production conditions into account,No.5 test(10%core-wall,40?,5h)was consindered as the best.The range analysis showed that the sequence from high to low which affected the microcapsule was core-wall ratio,embedding temperature,embedding time.The effect of temperature and humidity on the release of microcapsules is obvious.The microcapsules should be stored in an environment where the temperature is lower than23?and the relative humidity is lower than 30%.(4)Preparation and properties of antioxidant active packaging film.Through single factor test and response surface analysis,the optimum membrane preparation process was determined.The composite process of base membrane and chitosan film was studied.The obtained film was applied to rice-wafer to verify its antioxidant properties at last.The results showed that the three factors including microcapsule,ethanol and the amount of film-forming liquid added had significant effects on the release of essential oil,mechanical properties and optical properties of chitosan membrane.The optimal formula was optimized by response surface analysis as follows:4.29 wt%ethanol;1.02 wt%Microcapsule;29.8g film-forming liquid.The optimal process of chitosan film and base film was corona first and then doing dry type composite.The shelf life of rice-wafer prepared with composite film was predicted to be 18.2%longer than that prepared with base film under the accelerated test at 40?.