PHYSICAL PROPERTIES AND REHYDRATION CHARACTERISTICS OF DIFFERENT VARIETIES OF MAIZE (ZEA MAYS L.) AND COWPEA (VIGNA UNGUICULATA L. WALP) SEEDS

Rehydration characteristics of the maize (varieties MASYN VARS, IK93TZL COMP.3-YCI, ACR.86TZ ESR-W and IK937ZYTSR-W) and cowpea seeds (varieties 14C, 12C(2), 19C and 12C(1)) were investigated at 25, 35 and 45C using Peleg model. The physical characteristics of the seeds observed were different among the varieties studied. The Peleg model applied can predict effectively the kinetics of rehydration of the seeds with R2 varying between 0.871 and 0.99.The Peleg constant K-1 varied between 0.5773 and 1.177 min/% for maize seeds and 0.0604 and 0.2417 min/% for cowpea seeds. For the K-2, the effect of variety and temperature was observed in this work. The equilibrium moisture content within the experimental range varied between 13.03 and 18.66 kg/kg dry basis (d.b.) and 11.86 and 13.77 kg/kg d.b. for cowpea and maize seeds, respectively. Temperature dependence of 1/K-1 followed an Arrhenius-type relationship, and the activation energy was in the range of 330-11200 J/mol for maize and 3370-34820 J/mol for cowpea seeds. PRACTICAL APPLICATION The information presented in this work on physical properties and rehydration characteristics of different varieties of maize and cowpea seeds will be very useful in the determination of the behavior of these seeds during rehydration in an industrial environment. Also, information about rehydration characteristics of the seeds presented will also be very useful to optimize and characterize the soaking conditions, conserve energy, design food-processing equipment and predict water absorption as a function of time and temperature in order to enhance process and quality control as well as quality specification.