关键词: 超声波, 豆腐, 豆浆, 质构

Abstract: Ultrasonic treatments at different powers (0, 100, 200, 300, 400 and 500 W) were applied on soybean milk to evaluate their effects on the preparation and quality of freeze-dried tofu. The particle size distribution results showed that the average particle size of soybean milk gradually decreased with increasing ultrasonic power up to 300 W and then increased, which indicated that appropriate ultrasonic treatment could reduce the aggregation of soybean milk. Texture profile analysis showed that hardness, springiness, cohesiveness and chewiness of freeze-dried tofu after rehydration were significantly increased when compared with fresh tofu (P < 0.05), which indicated that protein denaturation occurred during the freezing process. Scanning electron microscope and rehydration rate demonstrated that appropriate ultrasonic treatment could result in uniform hole distribution of freeze-dried tofu with a simultaneous reduction in aperture. Therefore, freeze-dried tofu with good texture characteristics and high rehydration rate could be prepared by 10 min ultrasonic treatment at 300 W.

Key words: ultrasound, tofu, soybean milk, texture