Development and validation of rapid and cost-effective protocol for estimation of amylose and amylopectin in maize kernels.

Abstract

Maize possesses wide variation in amylose and amylopectin which assumes significance as a part of both food-chain and different industrial applications. Estimation of amylose and amylopectin in maize kernels is important for developing suitable hybrids. The existing protocols for estimation of amylose and amylopectin in maize are elaborate and lengthy, and involve high cost. Here, we developed a rapid and cost-effective method for estimation of amylose and amylopectin in maize kernels. 10% toluene and 80% ethanol were used for removal of proteins (~ 10%) and lipids (~ 4%) from maize flour. The over-estimation of amylose was minimized using NaOH with KI to stop free KI to bind with amylopectin. Standards were improved by mixing amylose and amylopectin in different concentrations (0-100%), rather than using amylose or amylopectin alone. Standard curve generated regression equation of y = 90.436x + 0.8535 with R 2 = 0.9989. Two types of samples viz., (1) protein, amylose and amylopectin (2) amylose and amylopectin, showed thatstarch fractions were highly comparable to expected values with correlation coefficient (r) of 0.9998 and mean standard deviation of 0.54. The protocol successfully estimated wide range of amylose (2.79-50.04%) and amylopectin (59.96-97.21%) among diverse maize inbreds including amylose extender1 (ae1) and waxy1 (wx1) mutants. Present protocol required 75% less time and 92.5% less cost compared to existing protocols. The newly developed method would be highly useful in developing maize hybrids high in amylose or amylopectin. This is the first report of rapid and cost-effective protocol for estimation of starch fractions in maize kernels.