Research On Technoligical Process And Properties Of Potato As Staple Food During Hot-air Drying

On 6 January 2015,the Ministry of Agriculture formally put forwardthe strategy of potato staple food with the core of processing potato into the popular principal food that fits in with the diet habits of Chinese people in order to ensure the absolute safety of food in China,adjust the farming structure and improve the dietary nutrition structure of Chinese residents.However,potato ismainly usedwithfresh and lack of farm produce suitable for the staple food in China which results in the low processing rate less than 10 percent and extremely limited addingvaluesofthe potatoproducts.So research and development of deep processed potato products is one of the important aspects of potato staple food.In this paper,potato was dried with hot-air drying technology,then drying process,drying model,product quality and drying cost were studied which provided the theoretical basis for the development of potato staple food.The main contents of this paper are as follows:1.The effects of hot air temperature,wind speed and diced length on the hot-air drying process and property of potato were studied by the drying test with thin-layer hot air.The results showed that the drying process of potato was mainly slow drying process,and the effective diffusion coefficient of water was significantly linearly related to hot-air temperature and wind speed with P less than 0.05.The activation energy was 19.107kJ/mol,which was lower than that of the general agricultural product,and was negatively correlated with the length of diced with P less than 0.05.2.The data from the potato drying tests were fitted with ten types of commonly used thin-layer drying models in the agricultural products,and the results show that the model of Weibull I could describe the mathematical model of drying process of potato aspreciselyaspossible,and provide stronger applicability for the hot-air drying of potato in the same time.3.We had analyzed the effects of drying process on colour,microstructure,thermal character,water absorption and oil absorption of dehydrated potato products,the results revealed the bigger the gelatinization enthalpy value,the lower the gelatinizatio n degree.Then the degree of ripening was adopted to measure the gelatinization degree of the dehydrated potato products,and provide the metrics for this production preparation.4.The production processes of dehydrated potato production were optimized by production colour,ripening degree and drying time based on the single-factor experiments.And the optimum technological parameters were as listed below:the hot-air temperature was63.49?;the wind speed was 1.5m/s;the diced length was 5mm;the?E~*value of chromatic aberration of the dehydrated production was 27.95;the S ripening degree was 22.44%,the?t drying time was 76.52min.5.The potato drying pilot tests were carried out in a box dryer utilizing the results of optimization tests.The obtained potato products after drying had bright color and low gelatinization degree with the gelatinization degree of 23.27 percent and the water absorption of 211.67 percent.The production costs of dehydrated potato products is 12094yuan/t from fire coal or 14417 yuan/t from fuel oil,the cost of raw materials is the most important factor affecting its processing costs.The study in this thesis provided theoretical basis and directions for the design of drying equipments,the optimization of production process and process control,the new access for intermediate material,and the product development of potato staple food.