Study of Intensification of Vaporization by Decompression to the Vacuum (IVDV) as an environment-friendly process on the expansion of maize

"Intensification of Vaporization by Decompression to the Vacuum" (IVDV) is a time and energy saving, environmental-friendly, texturizing process proposed as a pre-treatment for biological products. It consists in exposing humid products to high steam pressure, reached within 1 sec, for a defined time followed by a rapid decompression to the vacuum. It was studied in the aim of expanding hard maize kernels in order to prepare them for further roasting; knowing that, till nowadays, crunchy unpopped maize kernels could not be prepared other than by oil frying. Two maize varieties (M and G) were studied. After roasting, IVDV expanded kernels showed higher Expansion Ratios (ER) than non-expanded roasted ones. Response Surface Methodology (RSM) was applied to study the effect of the operating parameters (initial water content (W), steam pressure (P) and processing time (t)) on the expansion ratio of the kernels after IVDV processing and then after roasting. In both varieties and treatments, expansion ratio was greatly increased by P, t and the quadratic effect of the pressure P². The interactions between parameters all increased ER but to different extends. IVDV is a good process for expanding maize kernels without undergoing popping thus preparing them for further roasting.