Study On Technology And Model Of Garlic Cubes During Series Combined FD And MVD

At present, mainly traditional drying methods of garlic include drying in the sun, hot air drying, vacuum drying, fluidized bed drying, microwave drying, infrared drying and other drying methods. Different drying methods have their characteristics, but with the improvement of people’s living standard, people’s requirements on food quality are also rising. Most of these drying methods existe the problems of product quality.The technology of series combined FD and MVD can not only keep the products better sensory, better nutrient retention rate, high rehydration rate, to ensure product quality, and can be very good to save product drying time, speed up drying rate, reduce energy consumption and increase the added value of products. Therefore, the technology of series combined FD and MVD used in drying garlic has the significant practical significance. The main research contents are as follows:1.Through single factor experiment, by weighting four index (the drying rate, b value, allicin and rehydration rate), we have the L9 (34) orthogonal experiment. Optimum experimental parameters are as follows:microwave power(420W), moisture conversion (30%), paving layers (two layers).Based on the orthogonal experiment range analysis and variance analysis of optimized process parameters, the degree of influence of three factors is:water transfer point> paving layer> microwave power. Optimal conditions is A1B2C2. Moisture transfer point and paving layers to the series combination drying of garlic cubes have comprehensive effect. The effect of moisture transfer point to the combined drying of garlic cubes is the biggest. The effect of paving layers to the combined drying is secondly. Microwave power to the combined drying of garlic cubes don’t has comprehensive effect.2. Comprehensive analysis of different drying methods get the yellowness, whiteness, allicin, hardness before rehydration, rehydration rate,texture characteristics after rehydration, ultrastructure, microbiological hygiene indicators, energy consumption and so on. Compared with garlic cubes of single vacuum freeze drying, the series combination drying of garlic cubes have the similar quality and can greatly speed up the drying rate and save the energy consumption. The energy consumption of garlic cubes by single microwave vacuum drying is far lower than the former two kinds of drying, but the quality of garlic cubes by single microwave vacuum drying is poorer. So the single microwave vacuum drying is not suitable for high quality garlic grain production.3. The mass transfer model of series combined FD and MVD of garlic cubes were studied. In the vacuum freeze drying, temperature and paving layers on garlic vacuum freeze drying curve have important influence. The rate of material drying is gradually decelerating. In microwave vacuum drying, microwave power and the paving layers on garlic microwave vacuum drying curve also have important influence.In the drying process, we select the Lewis model, Henderson and Pabis model, Page model to describe the changes of water contents. Research shows that, no matter in the process of vacuum freezing drying process and microwave vacuum drying process, the Page model has the highest correction coefficient and the minimum standard deviation. At the same time, three kinds of model’s correction coefficient difference are significant. In three kinds of drying model, Page model has the best effect. We selects the Page model to fit the combined drying curve of garlic cubes.We determined the piecewise mathematical model of drying garlic cubes:MR= exp[-exp(-2.772+0.02T-0.294L)×t1.432+0.002T-0.007L] moisture content(% w.b.)≥30%MR=exp[-exp(-1.38-0.446L)×t0.213+0.001P+0.139L] moisture content(% w.b.)<30%The Page model can well describe the changes of moisture content of the garlic cubes in drying process.