Study On Drying Characteristics And Quality Of Purple Potato Chips By Microwave And Infrared Treatment

Purple sweet potato?Ipomoea batatas?is a special variety of sweet potato.Since its high nutritional value and economic value,it has become a new sales darling of major farmers'markets and supermarkets.However,fresh purple potatoes still have more moisture,which makes them perishable during storage and transportation,causing economic losses.Therefore,the research on drying technology and deep processing technology of purple sweet potato is one of the key points to expand the purple sweet potato industry.In this study,the effects of infrared drying technology and microwave drying technology on the drying characteristics and quality of purple potato chips were explored.Besides,when these two drying techniques were used for pre-drying,the impact on product quality was also explored.On the one hand,the infrared drying characteristics and microwave drying characteristics of purple potatoes were obtained,and the thermodynamic equations of these two characteristics were calculated.On the other hand,these two drying technologies were used in the production of purple potato crisps on the basis of characteristic research.This study provided a new idea and theoretical basis for the deep processing and industrialization of purple sweet potatoes.The main experimental results are as follows:In the process of drying purple sweet potatoes by infrared irradiation technology,it was found that the drying rate and the time taken to reach the drying end point of purple sweet potatoes were significantly affected by infrared radiation temperature and radiation distance.During this process,the effective moisture diffusion coefficient of purple sweet potatoes is between 6.49×10-10?9.16×10-10 m2/s,which was positively correlated with infrared radiation temperature,but negatively correlated with irradiation distance.This result showed that both the increase of the radiation temperature and the reduction of the radiation distance can help accelerate the diffusion of free water inside the material and the evaporation of the surface moisture,which increases the drying rate and shortens the time to reach the drying end point.The results prove that the infrared ray drying characteristics of purple potato chips conform to the Page equation,and the mathematical model of infrared ray drying of purple potato is MR=exp{-[?-1.492+0.004T?^{?-1.398-0.011T?}]}?In the process of drying purple sweet potatoes by microwave drying technology,it was found that the power of microwave drying and the loading amount of the working surface during drying had an influence on the microwave drying process of purple potato chips.Microwave power has the greatest effect on the drying process of purple sweet potato.With the increase of microwave power,the average drying rate of purple potato chips increases.As the loading capacity decreases,the time it takes to reach the end of drying is shortened and the moisture content is reduced.The microwave drying kinetic model of purple potato chips is most consistent with the Page equation,and the equation is MR=exp?-Ktⁿ?,K=-0.00416+0.00121 W+0.000130 G,n=1.7665+0.00423 W+0.000130 G.This equation can better predict the moisture change during the drying of purple potato chips,which plays a guiding role in the production of purple potato dried products by microwave drying technology.Microwave pre-drying technology and infrared pre-drying technology contributed to improve the production and processing technology of fried purple potato crisps.Both technologies could help purple potato crisp products to achieve better brightness,lower fat content,greater hardness and better crispiness.Purple potato crisps produced by microwave pre-drying technology contain relatively more anthocyanins,while infrared pre-drying technology was not conducive to the retention of anthocyanins.At the same time,the fat content of purple potato crisps produced by microwave pre-drying was lower than that of infrared pre-drying.However,the purple potato crisps produced by infrared pre-drying technology had better brightness,greater hardness and better brittleness.