Storage effects on flour quality of commonly consumed cereals
The present investigation was conducted to study the effect of storage period on flour quality of wheat, maize and pearl millet. Their flour were stored at 15 °C and 82 % relative humidity RH for one month and changes in fat acidity (FA), activities of peroxidase (POX), lipoxygenase (LOX) and polyphenol oxidase (PPO) in control and stored flour along with change in pH of water extract of flour were monitored. Increase in FA (mg KOH/100 g d.m.) and decrease in pH of flour was maximal in pearl millet (287.5 mg KOH/100 g d.m. and 0.4) followed by maize (151 mg KOH/100 g d.m. and 0.23) and wheat (61 mg KOH/100 g d.m. and 0.1) respectively. A decline in activity of POX, LOX and PPO was observed during storage. Pearl millet flour possessed almost double activity of POX (413 Units/g d.m.) in comparison to wheat (198 Units/g d.m.) and 1.3 fold higher than that of maize (153 Units/g d.m.) and even after decrease activity of POX was higher in flour of pearl millet compared to the other two. However, activity of LOX and PPO was found to be comparable in fresh flour of pearl millet, maize and wheat. Since pearl millet has poor shelf life and increase in FA, decrease in pH and activity of POX was found to be very high in pearl millet (poor shelf life) as compared to wheat and maize, therefore, these selected parameters might be used as biochemical markers to determine shelf life of flour.