Investigating cooked rice textural properties by instrumental measurements

Foods wherein the starch is slowly digested contribute to good health by reducing the tendency to, and for the maintenance of, diabetes, obesity and colo-rectal cancers. While foods with high amylose content have this desirable property, they usually do not have high sensory appeal and consumers are reluctant to eat them. While sensory evaluation by trained human panelists is the best way to obtain consumer preferences, these tests are expensive, time-consuming and require considerable effort and care. Instrumental measurements are easier, cheaper and invaluable for screening, but only useful if they correlate with human data for the type of food being considered. Here, we test this using cooked rice with a wide range of amylose contents. Functional properties were correlated against quantitative descriptive panelist analysis. Swelling power and breakdown viscosity correlated with all panelist sensory attributes, but no other correlations with gelatinization properties were observed. There was a strong correlation between hardness and stickiness measured by texture profile analysis (TPA) and by panelists, suggesting that TPA can be used to measure hardness and stickiness of cooked rice. We also showed that breakdown viscosity is a reliable instrumental means to provide indicative measurements of hardness and rice preference, and swelling power is a predictor of rice stickiness.