Study On Pore Fractal And Drying Characteristics Of Cooked Flour Cookies During Baking Process

This paper made the cooked flour(cooked green bean flour, cooked rice flour, cooked glutinous rice flour, cooked wheat flour into cookies based on the process of Cantonese almond cookie. For the demand of industrial production, this paper explored the effect of changes of the raw materials on moisture removal rules, effect of particle size and different types of oil on the drying characteristics and quality of cookies based on fractal theory. The purpose of this paper was to provide theoretical basis and practical guidance for the industrial production. The research findings were included:1. The investigated subjects were mung bean cookie, rice cookie, glutinous rice cookie, wheat cookie, a tunnel drying equipment was used to simulate the industrial tunnel oven. Explored the influence of different raw materials(powder, sugar, oil, water) on the mass transfer of cooked cookies. The results showed that for each drying process, the whole process was under the falling rate period. Powder granularity, oil, sugar had great impact on the drying rate.2. Scanning electron microscopy(SEM) and image analysis method were used to determine the pore micro-structure of cooked flour cookies. The effect of particle size on the drying properties and quality of cooked flour cookies were explored based on fractal theory. The results showed that:(1) Cooked flour cookies with low moisture content had porous structure and apparent fractal feature. The smaller the particle size was, the more complex the pore structure was.(2) Cookies made with 140 mesh had faster drying rate than those made with 60 and 100 mesh flour at 100 and 120 degrees.(3)Texture properties analysis(TPA) indicated that with the decrease of particle sizes(60meshâ†'100meshâ†'140mesh), the hardness, cohesiveness, chewiness of cooked flour cookies decreased significantly(P<0.05).(4) According to the sensory evaluation, the cookie made of 140 mesh powder had better quality. As a result, the size of the flour reduced in a certain range could improve the drying rate and guarantee the quality of the product when made the cooked flour cookies.3. Determined the effect of peanut oil, rapeseed oil, lard on texture properties, brittleness, internal structure, color, and sensory quality of mung bean cookie, rice cookie, glutinous rice cookie and wheat cookie. The effect of peanut oil on the cooked flour cookies were explored based on fractal theory. The result showed that:(1) rapeseed oil, peanut oil made the cookies harder, lower crisp than those made with lard, but were within the acceptable range. During the storage of cooked flour cookies,the cookies made with rapeseed oil had unpleasant flavor, resulting in a sharp decline in sensory quality.(2) Cooked flour cookies made with peanut oil had more complex pore structure, the increased porosity, more irregular pore section shape, uneven pore size distribution, so peanut oil could improve the drying rate of cooked flour cookies.