The Technology Research And The Shelf-life Prediction Of Oats-hawthorn Biscuits

This dissertation mainly aimed at developing a new type of oat-hawthorn biscuits by using oat flour and hawthorn as raw materials.The preparation technology and production formula of the biscuits were studied.The quality of oat-hawthorn biscuits were evaluated by a combinative method of sensory evaluation and instrumental analysis.Furthermore,the quality changes of oat-hawthorn biscuits were investigated by measuring the indicators including weight loss on drying,water activity,sensory properties and hardness during storage.The general stability index(GSI)was calculated out and the relationship regarding to the quality change with temperature and time as well as the prediction model of shelf-life was established according to Arrhenius equation.Extrusion expansion was applied to pretreat the raw oat flour and the effects of oat flour content,moisture content,extrusion temperature and extrusion speed on the sensory evaluation score and degree of expansion were investigated by single-factor experiment method.The optimal conditions were as follows:20%of oat flour content,76%of corn flour,4%of water adding(namely 15%of moisture content);160? of extrusion temperature and 100 r/min of extrusion speed.Then the influences of microwave power and microwave time for biscuit baking on the sensory evaluation score were studied and the optimal conditions were as follows:685 W of microwave power and 2 min of baking time.According to the single-factor experiments,response surface experimental design of four factors and three levels was conducted to optimize the formula of oat-hawthorn biscuits by taking sensory evaluation score as index.The effects of factors and their interactions on sensory evaluation score were studied.The optimal formulation of oat-hawthorn biscuits was determined.Under the protein fluid ratio of 2:1:7,the ratio of the amount of protein fluid,flour,hawthorn and sugar was 10.51:5.60:1.40:3.67.The verification test was also performed,showing that the math model was successfully established.The changes of weight loss on drying,water activity,sensory properties and hardness during the storage of oat-hawthorn biscuits were determined.The result indicated that the weight loss on drying and sensory quality gradually reduced,while water activity and textural quality firstly increased and then decreased during storage.The microbial indicators were in accordance with the related national standards.The GSI curve fitting suggested that the quality change of oat-hawthorn biscuits belonged to a zero-order reaction.The relationship regarding to the quality change with temperature and time was calculated out to be GSI=1-t×e-3363/T+5.9295,and the prediction model of shelf-life was established as follows:t=e(0.0003/T+0.0016).