Vacuum Microwave Drying Kinetics and Process Optimization of Purple Potato Chips

Abstract: The drying kinetics and optimumity of purple potato chips under vacuum pressures of -0.05, -0.06, -0.07 MPa, microwave power of 400, 500, 600 W and thickness of 2, 3, 4 mm were studied. Drying conditions.

The results show that the vacuum microwave drying equipment of purple potato chips is a fast and slow process. The microwave power has the greatest influence on the drying process of purple potato chips. The higher the power, the faster the drying rate. The drying kinetics fit found that the Page model is best suited to fit the change in moisture ratio during vacuum microwave drying of purple potato chips. Through the comprehensive evaluation coefficient and membership analysis of average drying rate, total color difference, anthocyanin content, swelling capacity, water absorption and oil absorption, the optimum process parameters for vacuum microwave drying of purple potato chips are: -0.05 MPa, 400 W, 2 mm.

Key words: purple potato microwave drying; vacuum microwave drying; kinetics; functional properties; anthocyanins

Purple potato belongs to the Solanaceae Solanum, which has been grown in South America for many years and has been introduced to China in recent years and has maintained a 5% annual growth rate. Compared with common potato, purple potato has higher nutritional value. Each 100g purple potato contains 0.49g of crude fat, 12.43g of starch, 0.83g of crude fiber, 10.43mg of vitamin B, and vitamin B21.90mg. And the skin and meat are rich in anthocyanins, so its antioxidant function and medicinal value are also increasingly favored by people.

Fresh purple potatoes have high moisture content, are not easy to store, and have a high rate of decay. Therefore, the selection of suitable drying techniques plays an important role in extending the shelf life of purple potatoes and retaining their active components and efficacy. The most common drying method is hot air drying. The equipment is simple, but the heat loss is large, the drying rate is slow, and the nutrients in the food are seriously damaged. Liu Jiayan and other studies have found that freeze-drying has little damage to the color of purple potato, and can better preserve the nutrients of purple potato. However, freeze drying has the disadvantages of long drying time and high cost.

Vacuum microwave drying technology is a combination of microwave and vacuum drying technology. It has the advantages of fast drying speed, high energy efficiency, uniform product quality and easy control. It has been widely used in dry carrot slices, oyster mushrooms, tilapia and apple slices. And other food. At present, there is no report on the drying of purple potato chips by vacuum microwave method, and the research on purple potato at home and abroad mostly focuses on physiological functions, and the research on the processing characteristics of purple potato is very limited.

The purpose of this study was to investigate the effects of vacuum pressure, microwave power and slice thickness on drying characteristics, moisture ratio changes and other physical and chemical indicators (including total color difference, anthocyanin content, swelling capacity, water absorption and oil absorption) during drying of purple potato chips. influences. Through the comprehensive optimization, the optimal process parameters of vacuum microwave drying purple potato chips were obtained, which provided a theoretical basis for the process research and production control of purple potato chips vacuum microwave drying.