THERMAL MODIFICATION OF NEW SORGHUM AND MILLET CULTIVARS: EFFECTS ON COMPOSITION, PROTEIN QUALITY AND FUNCTIONAL PROPERTIES OF FLOURS

Abstract

Driven by consumers’ need to limit gluten intake in their diets, the demand for gluten‐free products continues to grow in the foodservice industry. Two newly released sorghum and millet cultivars were thermally modified and their responses to the pre-gelatinization (PG) determined by evaluating their chemical compositions, amino acids profile and functional properties using standard procedures. Protein efficiency ratio, essential amino acid index, biological value, nutritional index and amino acid score were calculated from the amino acid profile. PG increased the total carbohydrate by 7% and 3.7% in sorghum and millet respectively. The millet showed significantly (p < 0.05) higher values of fat, carbohydrate and energy than did the sorghum, whereas the latter exhibited higher ash and protein content. PG significantly (p < 0.05) lowered the ash, fat and protein contents of both sorghum and millet flours. Of the essential amino acids (EAA) of the raw flours, millet exhibited significantly (P<0.05) higher values of histidine, isoleucine, methionine, phenylalanine, threonine, tryptophan, and valine, with no significant difference in leucine and lysine between the two grains. While PG induced increase in all the EAA in sorghum except phenylalanine, millet showed decrease in histidine, lysine and threonine. PG increased the EAA millet in valine by 11% followed by isoleucine (8%), threonine (7.3%), methionine (4.4%), phenylalanine (4.3%) and leucine (2.6%). significant (p < 0.05) increase of 82% and 12% in isoleucine and threonine. The WAC of raw millet flour (192.2%) was significantly higher than that of sorghum flour (189.7%), but PG reduced the WAC of both sorghum and millet flours by 11.9% and 12.5%, respectively. Results from the study indicated that pregelatinized sorghum and millet flours are good replacement as source of gluten-free products to meet varied consumers choices and changing dietary habits.