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Keywords:

  • spring wheat;
  • pre-harvest sprouting;
  • wheat proteins;
  • free asparagine

Abstract

BACKGROUND

High moisture before harvest can cause sprouting of the wheat kernel, which is termed pre-harvest sprouting (PHS). The aim of this study was to examine the variation in physicochemical properties of proteins in PHS-damaged (sprouted) hard red and white spring wheat genotypes. Specifically, protein content, enzyme activity and degradation of proteins were evaluated in sound and PHS-damaged wheat.

RESULTS

Protein contents of sprouted wheat samples were lower than that of non-sprouted samples; however, their differences were not significantly (P > 0.05) correlated with sprouting score. Sodium dodecyl sulfate (SDS) buffer extractable proteins (EXP) and unextractable proteins (UNP) were analyzed by high-performance size exclusion chromatography. PHS damage elevated endoprotease activity and consequently increased the degradation of polymeric UNP and free asparagine concentration in wheat samples. Free asparagine is known to be a precursor for formation of carcinogenic acrylamide during high heat treatment, such as baking bread. Free asparagine content had significant correlations (P < 0.01) with sprouting score, endoprotease activity and protein degradation.

CONCLUSIONS

Genotypes with higher endoprotease activity tend to exhibit a larger degree of degradation of UNP and higher free asparagine concentration in sprouted wheat samples. © 2013 Society of Chemical Industry