Physical and Mechanical Properties of Watermelon Rind

Watermelon rind is the toughest part of the whole fruit structure and usually peeled for processing purposes. A study was conducted to determine the physical and mechanical properties of watermelon rind to provide a reference for peeling process parameters to improve the efficiency of the process. A physical examination was conducted to determine the overall watermelon length and width, and rind thickness at different positions. The rind rupture force test was conducted at different penetration angles (0.0°, 22.5°, 45.0°, and 67.6°). The rind thickness was 1.46 ± 0.27cm (P<0.01). Based on visual observation, the differences in watermelon size affect the rind thickness. The rind thickness has a random distribution at different positions of the rind (P>0.01). Meanwhile, the rupture force showed that the direction of penetration angle significantly affects the rupture force value obtained (P<0.01), and it was directly proportional to the increase of penetration angles which ranged between 21.48N to 24.25N. Hence, the watermelon size and penetration angle factors should be considered before conducting the peeling process to ensure the process is run at an optimal level.