Abstract: Traditional tofu puffs have a high percentage of fat and become rigid upon frying at high temperature. To address this problem, this study developed and optimized a new low-temperature vacuum frying process. The results indicated that the optimum process parameters were frying time 7.5 min, oil temperature 95 ℃ and vacuum degree 0.085 MPa. The moisture content, oil content and sensory score of tofu puffs obtained under these conditions were 77.52%, 27.97% and 94 points, respectively. Texture properties and microstructures of tofu puffs produced using the new frying process were compared with those obtained using the traditional process. Texture profile analysis showed that the springiness and chewiness of low-temperature vacuum fried tofu puffs were those of traditional tofu puffs. Traditional tofu puffs had a more coarse surface with larger?aperture and lost more water as observed by scanning electron microscope. In conclusion, the optimized low-temperature vacuum frying process can provide experimental guidance for the tofu industry and other related industries.

Key words: tofu puffs, low-temperature vacuum frying, response surface analysis, sensory score, texture profile analysis, scanning electron microscopy