Water sorption isotherms of pistachio nuts

The adsorption and desorption isotherms of pistachio nuts (kernel and shell) were measured at 15, 25 and 40 degrees C using a gravimetric method. Hysteresis was more pronounced in the shell than in the kernel and reduced as the temperature increased. The isosteric hear of desorption, calculated from the slope of a lna(w) vs. 1/T plot, was higher than the isosteric heat of adsorption. The GAB equation gave satisfactory goodness of fit with average percent deviation of less than 5%. (C) 1996 Academic Press Limited