A rapid and convenient method for analysing alpha-amylase activity in wheat using an auto-analyzer and its application to estimation of maximum amylograph viscosity.

摘要

In order to estimate the maximum amylograph viscosity of wheat, an automatic method for the measurement of alpha-amylase activity was developed using a commercial blocked rho-nitrophenyl maltoheptaoside as a suitable substrate and a partially modified Type AAIIauto-analyzer (Bran + Luebbe). There was no significant difference between alpha-amylase activity measured manually and by the auto-analyzer. The alpha-amylase activity in flour correlated well with the maximum amylograph viscosity. The correlation coefficient between alpha-amylase activity and maximum amylograph viscosity was slightly lower in ground wheat. With regard to fresh wheat, there was no apparent relationship in wheat sampled before maturity, but a high correlation was exhibited after maturity. Studies of samples of fresh wheat showed that wheat grains with alpha-amylase activity below 300 mU/g had a high amylograph viscosity (mean = 755 BU), grains with alpha-amylase activity between 300 and 500 mU/g showed a wide range of viscosity (mean = 502 BU), while grains with alpha-amylase activity over 500 mU/g showed unacceptably low levels of amylograph viscosity (mean = 109 BU). It is concluded that the auto-analyzer could be used to rank wheat quality at reception points, and couldalso be adapted for use in selection for the development of low alpha-amylase wheat cultivars.