Study on Water Absorption Kinetics of Peas during Soaking

Abstract

The Peleg model equation and low-field nuclear magnetic resonance (LF-NMR) were utilized to study the water absorption process of pea during soaking, for the purpose of explaning the dynamic water absorbing process of peas from a new point of view. By immersing peas in the environment of different hydration temperature and different soaking time, and taking out every 1 h for testing the water absorption, pulse signal amplitude, and relaxation time. From the results, the changing of the water content in peas during soaking at 25~40 ℃ could be simulated by the Peleg equation. The constants K1 and K2 were obtained, the constant K1 decreased with the increasing of temperature, and the percentage deviation modulus E was less than 10%, and the activation energy (Ea) of the soaking process was 32.01 kJ/mol. In addition, there were three states of water in the pea soaking process, including strongly bound water, weakly bound water, free water. The soaking temperature rose, the content of free water and bound water increased first and then balanced, and the higher the temperature, the shorter the time to reach equilibrium. Finally, the optimal soaking time was determined to be 10 h.

Keywords

• pea
• soaking
• peleg equation
• low-field nuclear magnetic resonance
• water absorption kinetics