Changes in the properties of starch, nutrients and antioxidants in cereal flakes

Ready to Eat (RTE) cereal flakes from maize, wheat, rice, oats, sorghum, pearl millet, and barley were prepared by an appropriate method of processing. Steps involved in the flaking process were: cleaning, dehulling (oats), conditioning, hydrothermal treatment, drying and tempering, pearling, flaking, drying, sizing and blistering. Studies on the properties and behavior of starch, nutritional and antioxidant properties of these cereal flakes were conducted. Moisture content ranged between 11 to 12%; 9 to 11% and 4 to 5% (w.b) for grains, flakes and blistered flakes respectively. Equilibrium moisture content on soaking at room temperature (RT) was between 30 and 46% for grains, 64 and 81% for flakes and 72 and 78% for blistered flakes. Hydration behavior at room temperature indicated that grains absorbed up to 30 – 35% moisture, flakes: 65 to 80% and blistered flakes: 50 to 80%. Soluble amylose in these grains varied between 13 and 18%; total amylose between 20 and 29% (d.b). For flakes, soluble and total amylose ranged from 12 to 16% and 19 to 27% (d.b) respectively, whereas for blistered flakes it was 11 to 14% and 19 to 26% respectively. Swelling power and Solubility studies between 30 and 100 °C varied from 2 to 16; 2 to 29% respectively for the grains. For flakes, the values were 6 to 14%; and 7 to 46%, whereas for blistered flakes they ranged from 10 to 14%; and 8 to 49%. Pasting profile indicated that the peak viscosity varied from ∼360 to 924 BU for grains, while this parameter decreased for flakes as well as for blistered flakes. Microstructure of grains, flakes and blistered flakes studied by scanning electron microscopy will be discussed. On flaking, loss (%) of polyphenols, free radical scavenging activity and total antioxidant activity were 26–54, 24–66 and 30–44, respectively in some of the above mentioned grains. Ultimately the soluble polyphenols in flakes varied from 30 to 61 mg Ferulic Acid Eq: (FAE) per 100 g; bound polyphenols from 21 to 59 mg FAE: total polyphenols ranged from 52 to 121 mg FAE / 100 g. Free radical scavenging activity (% reduction of DPPH+) varied from 16 to 54 and total antioxidant activity (mM alpha Tocopherol Eq:/g) from 8.5 to 11.1. Flaking process results changes in functional and antioxidant properties and these properties vary from grain to grain.