Multiple optimization of chemical and textural properties of roasted expanded purple maize using response surface methodology

• Intensification of Vaporization by Decompression to Vacuum IVDV is applied on maize.
• IVDV relies on a very rapid steam pressurizing followed by decompression to vacuum.
• IVDV causes important texture modifications as crunchiness, popping or shrinkage.
• Multiple optimization of IVDV variables is done on texture & antioxidant properties.
• Roasting of IVDV texturized maize kernels preserve their antioxidant potential.

Intensification of Vaporization by Decompression to the Vacuum is a new texturizing process proposed as a pre-treatment for roasting purple maize. It consists in exposing humid kernels to a high steam pressure followed by a decompression to the vacuum. Three variables were considered: initial water content (W), steam pressure (P) and processing time (T). Using response surface methodology, the effects of these variables were studied on the response parameters: Total Anthocyanins Content, Total Polyphenols Content, Free Radical Scavenging Activity, Expansion Ratio, Hardness and Work Done. P and T had the highest effects. They decreased anthocyanins and polyphenols content but increased Expansion Ratio, Hardness and Work Done. Interactions between the variables had interesting effects on texturization as crunchiness, popping or shrinkage. Multiple optimization was conducted in order to find a compromise between chemical and textural parameters. The optimum (W = 30%, P = 7 bar, T = 10 s) conserved the phenolic compounds while conferring expansion and crunchiness.