Modulation of resistant starch and nutrient composition of barley grain using organic acids and thermal cycling treatments

Enrichment of cereals with healthy ingredients such as resistant starch (RS) may enhance their health value in human and animal nutrition. We recently observed some positive effects of citric acid (CA) and lactic acid (LA) on RS in barley. The main goal of this research was to evaluate potential additive effects of an additional thermal treatment on RS and other key nutrients of barley grain. Barley samples were steeped in 5% solutions v/v of CA or LA for 24 h, in two different temperatures (22 degrees C or oven heating at 50 degrees C), without or with a subsequent rapid cooling (4 degrees C) of the oven-heated barley. An additional treatment was a retrogradation cycle (first heating at 100 degrees C and then rapid cooling at 4 degrees C for 2 h each) after treatments with CA and LA. Both rapid cooling at 4 degrees C and retrogradation cycling doubled the RS content of barley compared to untreated control and chemical treatment alone. Chemical treatments decreased ash, protein, and insoluble fibers, but increased the recovery of the organic residues, a fraction that includes soluble fibers. These changes in the chemical composition of barley might contribute to an enhanced health value of the treated cereal, but more research is warranted to validate these findings in in vivo trials.