The impact of sodium carbonate on physico-chemical properties and cooking qualities of starches isolated from alkaline yellow noodles

The physicochemical and cooking properties of wheat starch isolated from alkaline yellow dough treated with sodium carbonate (Na₂CO_3; 0-3.2 g/100 g) were investigated. With increasing Na₂CO₃ addition, swelling power increased from 7.28 to 10.70 g/g. X-ray diffraction showed no changes in crystalline patterns while the relative crystallinity decreased from 30.11% to 23.13%. Differential scanning calorimetry results suggested that alkaline salt shifted the gelatinization peak of starch to higher temperatures. The values of pasting viscosity and pasting temperature in alkali-treated starch increased and decreased, respectively. Farinograph results revealed the strengthened structure of dough with alkali-treated starch that was manifested by an increase in the dough development time and dough stability time. Cooking loss and rehydration values of noodles prepared from alkali-treated starch increased by 42% and 36%, respectively. The results suggested that Na₂CO₃ affected starch crystalline structure, swelling power, gelatinization, pasting properties, starch-gluten interactions and cooking characteristics of noodle products.