Study On Processing Optimization Of Potato Slice Inactivation And Inactivation Mechanism Of PPO In Infrared Radiation

Potato industry becomes an important pillar industry of many farmers’revenue, for its being widely planted, rich in nutrition and more and more production. It is vital to inhibite browning for the product quality in potato processing especially in the processing of semi-finished productsPolyphenol oxidase (PPO) is the main enzyme in enzymatic browning reactiong. It exists in most of fruits and vegetables. In most cases, due to the effects of PPO, the browning will be not only detrimental to fruit and vegetable sense, impact of product marketing, but will also decrease the quality and flavor. Therefore, it is necessary to inhibit enzymatic browning to ensure the quality of products.In the inhibition of enzymatic browning methods, physical methods such as blanching, will cause the fruit texture soft and decrease its quality. Ultrasonic treatment, supercritical carbon dioxide treatments are also used to inactivate the PPO, but they both need very complex equipments. So these physical methods are clearly limited. Chemical methods in the food industry have been the most widely used in inhibition of the enzymatic browning. But the chemical inhibitors are exotic additives and they will cause the problems of food safety. Therefore, in enzymatic browning inhibition it is important to find out a physical method of enzymic inactivation which not only ensures the inactivation of PPO, retains the nutrition and quality of food, but also simplifies the equipment and reduces the investment.The changes of potato polyphenol oxidase relative activity, brightness, chromaticity and Vc content were inspected by comparing potato slice processed with infrared and hot water blanching inactivation process respectively. The optimum technology parameters were obtained by using multivariate nonlinear fitting method and they are as follows:When the infrared intensity is3.92kW/m2and the thickness of the slice is3mm, the processing time and Vitamin C remaining content would be1.46min and6.983mg/100g. When the blanching temperature is91.2℃with the same thickness of the slice, the processing time and the Vitamin C remaining content would be3.89min and7.068mg/100g. Compared with the traditional hot water blanching processing, the processing time can decrease by62.5%with infrared processing. Vitamin C remaining content can decrease decrease by only2.6%and at the same time the energy utilization can increase by58.6%. It would be more efficient.Using circular dichroism(CD) application to analyse structure changes of PPO after processing. Comparing the activity of PPO under the two processing, explore the thermal and the non-thermal mechanism of inactivation of PPO under the infrared processing from the secondary structure of protein. From the thermal effects, the inactivation of potato PPO in infared radiation is probably caused by a-helix turning to P-turn and random coil. From the non-thermal effects, infared radiation will decrease β-sheet content and this may accelerate the inactivation of PPO.The research in this paper will help to save the energy during the fruits and vegetables processing and to decrease environmental pollution. It can help people to explore more on the mechanism of potato PPO in infrared radiation from the micro structure.