The Study On The Key Technologies Of Candied Loquat Fruit During Processing

This paper focus on the critical produce process of sugar-preserved loquat, including exploring procedure conditions and changes of quality and characteristics. The main target of this article is to study the quality changes, such as how color protection, sugaring, and drying affect loquat characteristics on structure, sugar permeation rate, drying rate, color, flavor, taste, as well as nutrition preservation and micro-structure, for better use of thoroughly research on low sugar loquat changes during procedure texture differences when candied and dried and for rational use of sugaring and drying in order to produce high quality candied loquat.Main research results:1. Used repeatedly desalinating ways to dispose the loquat with salt content in 15% to 18% to for 12h.2. The study on color protection indicated: A combination of critic acid and Vc at concentration of 0.4% and 0.2% respectively can match the color protection effect of sodium bisulfate at the concentration of 0.3%.3. The water loss (WL) and solid growth rate (SG) of samples from different stages during the loquat sugaring procedure under atmospheric pressure, as well as certain micro organization are observed, and the results are:12 hours for first step of atmospheric sugaring(sucrose concentration at 30%), 21 hours for second step(sucrose concentration at 40%), more than 75 hours for the third step(sucrose concentration at 50%), and at less 40 hours for the forth step(sucrose concentration at 60%).4. The unit parameters of vacuum sugaring high-sugar loquat are as follows: vacuum degree of 0.08MPa, sugar concentration of 50%, vacuum sugar permeating temperature at 60℃, vacuum maintaining time for 1 hour, vacuum breaking time for 1 hour, vacuum breaking twice. Loquat under vacuum sugaring had shown less browning effect compared with atmospheric sugaring. After the vacuum gugaring procedure, the L* value increased, while the H decreased lower than that of loquat under atmospheric sugaring procedure.5. The hot air drying model of low sugar preserved loquat can be described using Page equation, MR=exp(-ktn), where k and n are related to the temperature of hot air, T. After regression fitting, the equation of MR = exp( ? e ( a + bP + cP 2 ) ? t(d + eP +fP2)) is significant that it can be used to predict water content changes of low sugar loquat when drying temperature is between 50-80℃,while a=-16.597,b=0.2471,c=-0.0013,d=1.9819,e=-0.0228,f=0.0001. The R2 of 0.9822 indicates excellent degree of fitting. 6. The microwave drying model of low sugar preserved loquat can be described using Page equation, MR=exp(-ktn), where k and n are related to the microwave power density P. After regression fitting, the equation of MR = exp( ? e ( a + bP + cP 2 ) ? t(d + eP +fP2)) is significant that it can be used to predict water content changes of low sugar loquat when microwave power density is between 1-5W/g, while a=-5.8931,b=0.6776,c=-0.0267,d=1.3565,e=-0.0498,f=0.0144. The R2 of 0.9455 indicates good degree of fitting.7. When microwave drying or hot air drying to dry low sugar preserved fruit loquat, the preserved loquat varieties will produce coking or hard rind, so a combination of microwave drying and hot air drying is used. The parameters of low sugar preserved loquat with microwave drying and hot air drying: the initial power density of microwave drying is 3W/g; when dried to 20% moisture content (22 min) ,then switch to 60℃hot air drying till 15% moisture content, the total drying time is 262 min. Whole drying progress mathematical model equations of low sugar preserved loquat are:(?)...