The objective of this research was to investigate the effect of Malva nut gum （MG） replacement on the pasting characteristics and freeze-thaw stability of wheat, rice or waxy rice flours. Pasting properties and free...The objective of this research was to investigate the effect of Malva nut gum （MG） replacement on the pasting characteristics and freeze-thaw stability of wheat, rice or waxy rice flours. Pasting properties and freeze-thaw stability of different flours incorporated with 0, 0.5%, 1%, 2%, 3% and 5% of MG were investigated. Pasting temperature （60 ℃-87 ℃） of the pastes significantly decreased with increasing of MG content for wheat and rice flours, but had no significant effect for waxy rice flour. Incorporation of MG into all flours significantly elevated the peak viscosity by about 0.9-2.6 folds when compared to non-MG samples. Hot paste viscosity, breakdown and final viscosity for all flour mixtures significantly increased with increasing of MG which ranged from 81-427, 37-559 and 152-463 RVU, respectively. Freeze-thaw stability measurement demonstrated that higher level of MG in wheat and rice gel mixtures could decrease syneresis. However, MG had no effect on syneresis of waxy rice gel. Presence of MG in flours alters the pasting properties and syneresis effect. It is suggested that higher viscosity and lower syneresis of gels could be modified by MG.展开更多
Resistant starch （RS） is the undigested starch that passes through the small intestine to the large intestine. As a functional low calorie additive, it has special applications in the food industry. Rapid visco anal...Resistant starch （RS） is the undigested starch that passes through the small intestine to the large intestine. As a functional low calorie additive, it has special applications in the food industry. Rapid visco analysis （RVA） and the Brabender farinograph were used to study the pasting properties and the viscoelasticity of blends of RS （RS3 and RS2） and three wheat flours. The wheat flours represented strong gluten wheat （SGW）, intermediate gluten wheat （IGW）, and weak gluten wheat （WGW） flours, at different levels of RS substitution （0, 5, 10, 15, and 20%）. The influence of RS3 on the control wheat flours and RS-wheat flour blends were consistent with those of RS2. The peak, trough, and final viscosities of RS3-wheat flour blends were higher than those of the corresponding RS2-wheat flour blends. The peak, trough, breakdown, final, and setback viscosities ofwheat-RS blends decreased with an increase in resistant starch contents from 0 to 20% in the blends. The 0-20% RS-wheat flour blends were all able to form doughs. The dough development times, dough stabilities, dough breakdown times, and farinograph quality numbers for the RS-wheat flour blends decreased as the RS proportion in the blends increased. The values for RS-SGW flour blends were the highest, followed by RS-IGW and then RS-WGW flour blends. The water absorption values for RS-wheat flour blends and the mixing tolerance index for RS-WGW flour blends were found to increase significantly with an increasing proportion of RS from 0 to 20%, but the mixing tolerance index for RS-SGW and RS-IGW flour blends showed no significant differences amongst the different ratios. Correlation analysis showed that the Farinograph quality number was highly positively correlated with dough breakdown time, dough stability, and dough development time （r= 1.000, 0.958, 0.894）, and highly negatively correlated with the mixing tolerance index （r =-0.890）. Data from this study can be used for the development of dough-based products. It also provides a basis for RS-wheat flour blends and quality evaluation in the food industry.展开更多
Background:Wheat flour maturation affects the aggregation and structural stability of proteins.The number of high-molecular-weight glutenin subunits(HMW-GSs)differs in various wheat varieties.The effects of Dx2 absenc...Background:Wheat flour maturation affects the aggregation and structural stability of proteins.The number of high-molecular-weight glutenin subunits(HMW-GSs)differs in various wheat varieties.The effects of Dx2 absence on the protein aggregation characteristics and thermal sta-bility of flour were investigated during 120 d of maturation using near-isogenic lines(NILs).Results:The absence of Dx2 delayed and decreased the protein aggregation of flours during maturation,i.e.the maturation-induced increases were later and smaller for glutenin,glutenin macropolymer(GMP),glutenin/gliadin ratio,β-sheets,andβ-sheet/a-helix ratio in HMW-D1a without Dx2 than in HMW-D1p with Dx2;these differences were ascribed to the weaker interactions between the sulfhydryl(-SH)groups,disulfide bonds(-S-S-),and hydrophobicity in the flours without Dx2.Flour maturation caused the dough microstructures to be more compact and denser,thereby increasing the flour thermal stability as observed by a higher denaturation peak temperature(Tp),enthalpy of thermal transition(△H),and degradation temperature(Td),These changes led to better dough properties such as dough development time,dough stability time,and protein weakening,but the optimal stage in HMW-D1a without Dx2was reached later.Conclusion:These findings deepen the understanding of how HMW-GS Dx2 modifies protein structures during flour maturation.展开更多
文摘The objective of this research was to investigate the effect of Malva nut gum （MG） replacement on the pasting characteristics and freeze-thaw stability of wheat, rice or waxy rice flours. Pasting properties and freeze-thaw stability of different flours incorporated with 0, 0.5%, 1%, 2%, 3% and 5% of MG were investigated. Pasting temperature （60 ℃-87 ℃） of the pastes significantly decreased with increasing of MG content for wheat and rice flours, but had no significant effect for waxy rice flour. Incorporation of MG into all flours significantly elevated the peak viscosity by about 0.9-2.6 folds when compared to non-MG samples. Hot paste viscosity, breakdown and final viscosity for all flour mixtures significantly increased with increasing of MG which ranged from 81-427, 37-559 and 152-463 RVU, respectively. Freeze-thaw stability measurement demonstrated that higher level of MG in wheat and rice gel mixtures could decrease syneresis. However, MG had no effect on syneresis of waxy rice gel. Presence of MG in flours alters the pasting properties and syneresis effect. It is suggested that higher viscosity and lower syneresis of gels could be modified by MG.
基金the National Natural Science Foundation of China （30671270）the National High Technology R ＆ D Program of China （2006AA100101）.
文摘Resistant starch （RS） is the undigested starch that passes through the small intestine to the large intestine. As a functional low calorie additive, it has special applications in the food industry. Rapid visco analysis （RVA） and the Brabender farinograph were used to study the pasting properties and the viscoelasticity of blends of RS （RS3 and RS2） and three wheat flours. The wheat flours represented strong gluten wheat （SGW）, intermediate gluten wheat （IGW）, and weak gluten wheat （WGW） flours, at different levels of RS substitution （0, 5, 10, 15, and 20%）. The influence of RS3 on the control wheat flours and RS-wheat flour blends were consistent with those of RS2. The peak, trough, and final viscosities of RS3-wheat flour blends were higher than those of the corresponding RS2-wheat flour blends. The peak, trough, breakdown, final, and setback viscosities ofwheat-RS blends decreased with an increase in resistant starch contents from 0 to 20% in the blends. The 0-20% RS-wheat flour blends were all able to form doughs. The dough development times, dough stabilities, dough breakdown times, and farinograph quality numbers for the RS-wheat flour blends decreased as the RS proportion in the blends increased. The values for RS-SGW flour blends were the highest, followed by RS-IGW and then RS-WGW flour blends. The water absorption values for RS-wheat flour blends and the mixing tolerance index for RS-WGW flour blends were found to increase significantly with an increasing proportion of RS from 0 to 20%, but the mixing tolerance index for RS-SGW and RS-IGW flour blends showed no significant differences amongst the different ratios. Correlation analysis showed that the Farinograph quality number was highly positively correlated with dough breakdown time, dough stability, and dough development time （r= 1.000, 0.958, 0.894）, and highly negatively correlated with the mixing tolerance index （r =-0.890）. Data from this study can be used for the development of dough-based products. It also provides a basis for RS-wheat flour blends and quality evaluation in the food industry.
基金supported by the Key Science and Technology Project of Shaanxi Agricultural Collaborative Innovation and Extension Alliance(No.LMZD202104)the Introduction of Talents for Scientific Research of State Key Laboratory of North China Crop Improvement and Regulation(No.NCCIR2020RC-11).
文摘Background:Wheat flour maturation affects the aggregation and structural stability of proteins.The number of high-molecular-weight glutenin subunits(HMW-GSs)differs in various wheat varieties.The effects of Dx2 absence on the protein aggregation characteristics and thermal sta-bility of flour were investigated during 120 d of maturation using near-isogenic lines(NILs).Results:The absence of Dx2 delayed and decreased the protein aggregation of flours during maturation,i.e.the maturation-induced increases were later and smaller for glutenin,glutenin macropolymer(GMP),glutenin/gliadin ratio,β-sheets,andβ-sheet/a-helix ratio in HMW-D1a without Dx2 than in HMW-D1p with Dx2;these differences were ascribed to the weaker interactions between the sulfhydryl(-SH)groups,disulfide bonds(-S-S-),and hydrophobicity in the flours without Dx2.Flour maturation caused the dough microstructures to be more compact and denser,thereby increasing the flour thermal stability as observed by a higher denaturation peak temperature(Tp),enthalpy of thermal transition(△H),and degradation temperature(Td),These changes led to better dough properties such as dough development time,dough stability time,and protein weakening,but the optimal stage in HMW-D1a without Dx2was reached later.Conclusion:These findings deepen the understanding of how HMW-GS Dx2 modifies protein structures during flour maturation.
