Effect of Hot Air Convection Drying Temperatures on Physical and Chemical Properties of Germinated Sweet Corn

Abstract

The effects of hot air drying temperatures (40-80°C) on apparent density, void fraction, shrinkage, total phenolics, total flavonoids and reducing power in germinated corn were investigated. The physical properties: apparent density, void fraction and shrinkage at moisture contents ranging from 13 to 35% dry-basis were determined using standard techniques. The result found that apparent density and the void fraction were linear in relation to the initial moisture contents. The apparent density increased from 44 to 50 kg/m3. The void fraction decreased from 78 to 58% with increasing moisture content. The chemical property resulted in 40°C hot air convection drying enhances total phenolics and total flavonoids to 6.41% and 50.00%, respectively, when compared with the control. Higher drying temperature resulted in lower total phenolic, total flavonoid content and reducing power of germinated sweet corn compared with the control.

Is air-drying of plant-based food at low temperature really favorable? A meta-analytical approach to ascorbic acid, total phenolic, and total flavonoid contents

“…Decrease in TPC with the increase in drying temperature above 60°C can be explained by the thermal degradation (11,13), ability of binding phenolic compounds to proteins and changes in chemical structure leading to the low extraction efficiency. (2) In general, the temperature has negative effect on the total phenolic content but the formation of phenolics at higher temperatures has also been observed.…”

“…While decrease in TPC with the increase in temperature from 40°C to 70°C was published for cocoa bean (10), sweet corn (11), tomatoes (12), carrots (13), gac fruit (14), leaves of Stevia (15) or jaboticaba fruit (16), the increase in TPC with the increase of drying temperature was observed for apple (17), ginger rizome (18), cucumber (19) or quinoa seed (20).…”

“…Total flavonoids content (TFC) also showed both decrease (11,15,21,22) and increase trends (24)(25)(26) with the increase in temperature in the range from 40°C to 70°C.…”