Investigation of soaking water produced by ultrasound-assisted chickpea soaking process

The soaking step of dry pulse products' – e.g. chickpeas' – food processing is a time consuming process. Soaking time can be significantly reduced by ultrasonic treatment or using higher processing temperatures. The effect of ultrasonic treatment can be investigated by examining the soaking water characteristics. Ultrasound-assisted soaking of chickpeas was performed at 25, 35 and 45 °C, respectively. Additionally, control samples were also prepared without ultrasonic treatment at the same temperatures. The dynamics of the fitted curve clearly shows the relationship namely the higher the treatment temperature, the faster the hydration of the raw material for both untreated and treated groups. In contrast to control group, swelling rate of 2.00 – except the group 45 °C – is not achieved during ultrasound-assisted soaking. In case of treated group, the swelling rate was about 1.90 for all temperatures applied. The ANOVA test shows that the color of the ultrasonically treated samples was significantly different compared to the control (F (5;12) = 207.86; P < 0.001). Average dry matter content and °Brix value were significantly higher in the ultrasound treated group compared to the control in case of all temperatures. This may indicate the destructive effect of ultrasound, which may cause more components to dissolve out of the raw material by the end of the soaking process.