Effect of drying methods on the functional properties of soy hull pectin

Soy hull pectin preparations produced by freeze drying, spray drying, and vacuum oven drying were evaluated for their surface chemical structure, degree of esterification, appearance, solubility, and flow behavior. FTIR spectral analysis showed no major structural differences in soy pectin samples produced by various drying treatments and their surface structures were comparable to that of analytical and food grade commercial pectin samples. Yields, galacturonic acid contents, and the degrees of esterification for oven dried, freeze dried, and spray dried soy pectin samples were 16-21, 67-69, and 18-20%, respectively. Pectin produced by oven drying had the lowest Hunter values for brightness, redness, and yellowness among the pectin samples produced by various drying methods. Drying methods did not have any significant detrimental effect on the solubility and flow behavior of the soy hull pectin samples.