Development of a Novel Pressure Vessel System for the Simulation of Starch Expansion – Methylated and Regular Waxy Corn Starch Behave Significantly Different With and Without Cellulose Inclusion

Abstract

Fortification of direct‐expanded products with insoluble fiber generally leads to decreased expansion. Understanding the interactions between starches and fibers can help to include more fiber into puffed products. A pressure vessel setup is developed to allow for a small‐scale expansion process. Because trends for the expansion ability during the simulated process are similar to those during extrusion, the setup has been proven to be suitable for understanding the occurrences during extrusion. Elimination of hydroxyl groups through starch methylation can help to understand the role of hydrogen bonding during expansion. Nonmethylated and methylated starch are tested for their expansion at cellulose levels of 0%, 5%, and 20% on a weight basis. The specific volume of the obtained samples is used to determine the degree of expansion. The nonmethylated starch sample exhibits a specific volume of 16.3 ± 1.8 cm3 g−1, which is almost three times higher than the one of the methylated sample (≈6.0 cm3 g−1). Possible reasons for this decrease are the elimination of hydroxyl groups capable of forming hydrogen bonds or the significantly higher viscosity of the methylated starch. While fortification with 5% cellulose does not affect the expansion, 20% cellulose greatly reduces the specific volume for both starches.