Drying characteristics and quality optimization of papaya crisp slices based on microwave vacuum drying

Abstract

In order to improve the drying quality and obtain a crispy texture of papaya slices, microwave vacuum drying (MVD) was studied in this research. The effects of different slice thickness (3, 6, 9, 12 mm), microwave power density (6, 8, 10, 12 W/g), drying temperature (50, 55, 60, 65, 70°C), and vacuum degree in relative pressure (−75, −80, −85, −90 kPa) on the drying characteristics and comprehensive quality of papaya slice were discussed. The Box–Behnken central combination experiments were designed and the response surface optimization analysis was carried out. According to the results of the response surface experiments, the impact factors during papaya slices drying on the comprehensive score were ranked from largest to smallest as follows: microwave power density, vacuum degree, and drying temperature. The fragility and hardness of papaya slices showed an upward trend with the increase of thickness. The optimum technologic parameters were set at the microwave power density of 10 W/g, vacuum degree of −90 kPa, drying temperature of 54.58°C, and slice thickness of 6 mm. The comprehensive score F can be up to the maximum value of 8.80 with the deviation from the verification test of 4.4%, and the papaya slices with obvious pore structure and remarkable crispness were obtained. Novelty impact statement Microwave vacuum drying technology combines the advantages of microwave drying and vacuum drying, which has remarkable drying efficiency through internal heating and promotes the slices to form a crispy texture. In this work, the influence of different factors on the fragility and hardness quality of papaya chips were explored firstly. Increasing drying temperature has no significant influence on the fragility and hardness value. Meanwhile, the hardness value went up while the fragility fluctuated slightly as the power density was added. The variation trend of papaya porosity microstructure gradually expanded with the increase of vacuum degree. The results provided theoretical support for the application of microwave vacuum drying technology in papaya crisp chips.