Shelf life determinants and enzyme activities of pearl millet: a comparison of changes in stored flour of hybrids, CMS lines, inbreds and composites

Abstract

Shelf life of pearl millet flour is very short because of rapid development of rancidity. This investigation was carried out in view of generating breeding material for development of low rancid pearl millet hybrids/varieties. Flour of twenty-one genotypes; seven hybrids, seven CMS lines, five inbreds and two composites stored in covered aluminium boxes at 37 °C for 30 days along with respective fresh flour was analysed for shelf life indicators/determinants. Crude fat content and fat acidity (FA) of fresh flour of the genotypes varied from 3.8 to 7.2% and 11 to 75 mg KOH/100 g d.m., respectively. FA in stored flour ranged between 180 and 330 mg KOH/100 g d.m. After storage, magnitude of decrease in pH of water extract of flour of the genotypes varied from 0.15 to 0.44. Activity of peroxidase (POX) varied from 378 to 588 units in control flour and irrespective of the genotypes decreased upon storage. Increase in FA (difference between FA of fresh and stored flour) rather total build up of FA was positively associated with crude fat content (r = 0.440*) indicated comparatively more prominent role of lipolytic enzymes. Chemical changes taking place in water soluble fraction of flour were independent of fat content as no correlation was discerned between fat content and decrease in pH. Among the hybrids, HHB 197 had lowest crude fat content (4.7%), lowest total build up FA (212 mg KOH/100 g d.m.), slowest increase in FA (191 mg KOH/100 g d.m.), least decrease in pH (0.31) of water soluble fraction flour during storage and lowest activity of POX in fresh flour (377 units/g d.m). Among all the tested CMS lines, inbreds and composites, HBL 11 showed pattern of quantitative changes in FA, pH and POX activity similar to the hybrid HHB 197 and was identified a promising inbred for developing low-rancid pearl millet variety or hybrid.

Descriptive sensory analysis of instant porridge from stored wholegrain and decorticated pearl millet flour cooked, stabilized and improved by using a low‐cost extruder

“…Painty aroma has been attributed to the presence of volatile pentanal, hexanal, and heptanal (Malcolmson et al., 1996); and soapy aroma attributed to the presence of decanal, 2( E )‐heptanal and octanal (Griglione et al., 2015). Hence, extrusion cooking most likely retarded the development of flour rancidity through thermal inactivation of lipase and lipoxygenase enzymes (Goyal & Chugh, 2017) and possibly also through enhancement of complexation of lipids with starch, thereby limiting their susceptibility to oxidation by entrapment (Wang et al., 2014).…”

Effect of thermal treatments on the matrix components, inherent glycemic potential, and bioaccessibility of phenolics and micronutrients in pearl millet rotis

“…Crude enzyme preparation and enzymatic activities of lipase and lipoxygenase were determined as per the method of Goswami et al 31 Peroxidase and polyphenol oxidase were assayed as per the method of Goyal and Chugh 32 with slight modifications.…”

Gene Editing to Accelerate Crop Breeding

“…Rancidity in pearl millet flour, which is caused by oxidation of unsaturated fatty acids released by lipases, limits its shelf life ( Goyal and Chugh, 2017 ). It could potentially be reduced by addressing a few qualitative steps in fatty acid formation and triglyceride hydrolysis.…”

“…An alternative could be to replace the native promoter of FAD2 with the one that is not expressed, or is expressed at a low level, in the seed but is expressed normally in other tissues ( Shi et al, 2017 ). Lipases, which release fatty acids from triglycerides upon grinding of the grains into flour, offer an alternative target to reduce rancidity in pearl millet ( Goyal and Chugh, 2017 ).…”