Effect Of γ-ray Irradiation On Hot-air And Microwave Drying Characters And Qualities Of Carrot

Besides sterilization,γ-ray irradiation can increase the water activity and improve the drying rate. In this thesis, y-ray irradiation was used to pre-treat the carrot before hot-air drying and microwave drying. In the hot-air drying process, the irradiation dose, air temperature and the thickness of the slice are selected as experimental factors. Single factor analysis and multi-analysis are employed to investigate the effect of three factors on drying characteristics and quality of carrot. In the microwave drying process, the irradiation dose, the thickness of the slice and emission power per unit mass thickness of the slice are selected as experimental factors in the single factor analysis, the results showed only the effect of the emission power per unit mass on the drying characteristics is significant. Therefore, the irradiation dose, the mission power per unit mass of the first drying phase and the second drying phase, as well as the drying time of the first phase are selected as the experimental factors. Single factor analysis and multi-analysis are employed to investigate the effect of four factors on drying characteristics and quality of carrot. At the same time, the effect of the irradiation on the water activity and the micro-structure are studied.1. Effect of irradiation pre-treatment on drying characteristics and the quality of carrot in the hot-air drying process1) It is found that the effect of the irradiation doses on the microstructure water and activity-are significant, and those are the reasons why the dying rate increase as the irradiation increase.2) Basing on the single factor analysis and multi-analysis, the effects of the three factors on drying characters are significant. And in the drying process, the surface temperature increase as the irradiation dose increases.3) Based on the six empirical models, better models affected by three factors are founded. 4)Based on quadratic rotation-orthogonal composite experimental design, the second-degree polynomial models affected by the three factors are founded. These models can effectively forecast the effect of three factors on drying time, carotene content, rehydration, sensory evaluation values.2. Effect of irradiation pre-treatment on drying characteristics and the quality of carrot in the microwave drying process1) The results are shown only the effect of the emission power per unit mass on the drying characteristics is significant.2) Based on the six empirical models, better models affected by first-degree and the second degree of the emission power per unit are founded.3)Based on quadratic rotation-orthogonal composite experimental design, the second-degree polynomial models affected by the four factors are founded. These models can effectively forecast the effects of four factors on drying time, power consumption, carotene content, rehydration, sensory evaluation values.