Dough properties and loaf quality stability in wheat cultivar Jimai 20 and their relationship with protein fractions

A total of 24 samples of newly released high quality cultivar Jimai 20 collected from 2005–2006 cropping season at 24 locations were used to evaluate quality traits, and quantify the protein fractions by reversed-phase high-performance liquid chromatography (RP-HPLC) and size-exclusion high-performance liquid chromatography (SE-HPLC) methods. Relations between the quantity of protein fractions and dough properties, and pan bread quality were analyzed. The results indicated that except kernel hardness, farinogram dough development time and stability and loaf spring, most quality traits showed small variation as determined by coefficients of variation across locations. Dough property and bread quality were mainly affected by test weight, grain hardness and protein content. Grain hardness was significantly and positively correlated with dough extension area and maximum resistance, with correlation coefficients of 0.53 (P<0.01) and 0.47 (P<0.05), respectively. Kernel protein content was significantly and positively correlated with dough water absorption, development time and extensibility, with correlation coefficients of 0.46 (P<0.05), 0.71 (P<0.001) and 0.77 (P<0.001), respectively. Test weight and grain hardness were significantly and positively correlated with loaf score, with correlation coefficients of 0.62 (P<0.01) and 0.50 (P<0.05), respectively. Kernel protein content was significantly and positively correlated with loaf volume (correlation coefficient = 0.55，P<0.01). The quantity of total glutenin and gliadin, SDS extractable polymeric protein and quantity of HMW-GS and LMW-GS were significantly and positively correlated with dough development time and extensibility, with correlation coefficients of 0.55–0.79 (P<0.01 or P<0.001), and the ratio of HMW-GS to LMW-GS was positively correlated with dough extensibility(correlation coefficient = 0.46, P<0.05). The quantity of HMW-GS and the ratio of HMW-GS to LMW-GS were significantly and positively correlated with loaf volume (r= 0.66 and 0.64, P<0.001), respectively. Percent SDS-unextractable polymeric protein (UPP%) was significantly and positively correlated with loaf structure and loaf score, with correlation coefficients of 0.53 (P<0.01) and 0.48 (P<0.05), respectively. The information has potential value for improvement of quality stability in China.

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