小麦蛋白质的特性与面条品质

面条是中国、日本、韩国等国家的主要食品之一,其品质关系到多数人的健康。现介绍面条的品质评价、小麦蛋白质的组成特性以及小麦蛋白质的含量、组成和特性与面条之间的关系。     

Quantification of monomeric and polymeric wheat proteins and the relationship of protein fractions to wheat quality

Wheat protein composition is important for understanding the biochemical basis of wheat quality. The objective of this study was to design a simple protein fractionation protocol with low cross‐contamination and to show that these protein fractions were associated with wheat quality. The protocol consists of three sequential extractions from 100 mg of flour with 7.5% propan‐1‐ol and 0.3 M sodium iodide (monomeric‐rich protein), 50% propan‐1‐ol (soluble glutenin‐rich protein) and 40% propan‐1‐ol and 0.2% dithiothreitol (insoluble glutenin‐rich protein). Nitrogen content of protein solubility groups was determined from dry residues using an automated combustion nitrogen analyser. About 90% of the total protein in the flour was solubilised. Cross‐contamination of protein fractions was evaluated by SDS‐PAGE, SE‐HPLC and RP‐HPLC. Variation in nitrogen content of the protein solubility fractions was lowest for monomeric‐rich protein (<2%) and insoluble glutenin‐rich protein (<4%). Three wheats with similar high‐molecular‐weight (HMW) glutenin subunit composition, Alpha 16, Glenlea and Roblin, varied significantly (P ≤ 0.05) in the proportion of monomeric‐rich and insoluble glutenin‐rich protein in the flour. Dough rheological properties were directly related to the proportion of insoluble glutenin‐rich protein and inversely related to the proportion of monomeric‐rich protein. The protocol was validated using an expanded set of 11 wheats which also showed that inter‐cultivar differences in the proportion of monomeric‐rich, insoluble glutenin‐rich protein and glutenin‐to‐gliadin ratio in the flour governed dough rheological properties such as mixograph, farinograph and microextension tests. The protocol has merit for quality screening in wheat‐breeding programmes when the sample size is too small or when time constraints limit the ability to perform traditional rheological tests. For the Department of Agriculture and Agri‐Food, Government of Canada, Copyright © Minister of Public Works and Government Services Canada 2003. Published for SCI by John Wiley & Sons, Ltd.     

The protein quality of some Indian dishes prepared from wheat

The protein quality of Indian dishes prepared from whole wheat and refined wheat flour were measured in N-balance experiments with growing rats. All samples were also analysed for amino acids. The levels of lysine, methionine, cystine and tryptophan were slightly reduced by processing. As a result, with the exception of a dish prepared by deep fat frying, the net protein utilisation of the dishes were approximately 5% lower than those of the corresponding unprocessed samples. True digestibility, however, was in general only slightly influenced by the processing.     

花生蛋白粉的功能特性及对面粉品质的影响

研究了花生蛋白粉的部分功能特性及添加花生蛋白粉对小麦粉品质的影响。研究表明,花生蛋白粉的吸油性保持在0.8～1.2mL/g,持水性在1.0g/g左右,持水性随pH的上升略有上升。在面粉中添加3%的花生蛋白粉面筋筋力最强,添加量为6%时对缓解面粉的弱化速度效果最好,且温度到90℃时,各种添加量面粉的酶仍然有一点活性。     

小麦粉中蛋白质和淀粉含量对面条品质的影响

对小麦粉中的蛋白质和淀粉组分进行了分离,将淀粉含量不同的混合粉制作成面条,分析其质构特性和食用品质。将面条煮制后,对熟面条进行了质构分析,测定了熟面条的硬拉伸性能、剪切性能和蒸煮损失,并进行了感官品质评价。研究结果表明:随着小麦粉中的淀粉含量的增加(蛋白质含量的降低),面条的质构特性、拉伸性能、剪切性能都呈现显著下降的变化趋势(P<0.05),而面条的蒸煮损失显著增加(P<0.05)。此外,面条的感官评价与质构分析的结果相一致。     

小麦品质与食品品质研究现状

对小麦品质与食品加工研究现状进行了综述,同时详细介绍了小麦蛋白质含量、亚基、淀粉性状对食品品质的影响及目前研究进展.     

Relationship between protein nutritive quality and technological property parameters of wheat flour

The biological value of proteins as well as their importance for the technological quality of wheat flours have been extensively researched. Apart from the other factors, gluten content, structure and functional characteristics are responsible for the flour's technological properties. Functional properties of gluten complex and thus also rheological properties of flour are influenced by the specificity and intensity of interactions among individual protein fractions and likewise of protein interactions with other flour components. Rheological properties of flour and quality parameters of bread are changed to a greater or lesser extent, among other, by addition of free amino acids. The purpose of this work was to explore the relationship between certain essential amino acids of wheat flour and the parameters of flour rheology and bread baking quality.     

不同干燥方式对小麦拉丝蛋白素牛肉干品质的影响

为使即食小麦拉丝蛋白食品具有牛肉干的风味和口感,研究了真空油炸(VF)、常压油炸(AF)、高温烘烤(HB)和微波加热(MH)干燥方式对含水量在(20±2)%小麦拉丝蛋白素牛肉干品质的影响。考察4种干燥方式对小麦拉丝蛋白素牛肉干品质的影响。测定小麦拉丝蛋白素牛肉干色泽、组织化度、质构特性(TPA)、水分分布及感官评定的变化。结果表明:相比其他3种干燥方式,真空油炸制备小麦拉丝蛋白素牛肉干具有明亮的淡棕色,产品组织化度达到1.85±0.05,咀嚼度最高达到(6 766.87±174.73)g·s,总体接受度达到8.53±0.34,水分分布较为均匀并呈现明显的梯度分布。利用真空油炸制备小麦拉丝蛋白素牛肉干最为接近传统牛肉干。     

Effect of wheat flour protein compositions on the quality of deep-fried gluten balls

Wheat flours milled from five different varieties of wheat and collected at an extraction rate of 60% were used as raw materials in this study. The proximate compositions, dough Farinographic and Extensographic properties, and the quality indices of deep-fried gluten balls prepared from these flours were measured. The proteins of these five different wheat flours were extracted and analyzed using the electrophoretic method, and the effect of protein composition on the quality of deep-fried gluten balls prepared from these flours was investigated. In this study, the proteins in each sample were divided into six groups, and the molecular weights of the proteins in these six groups are as follows: (I) 205.0–97.4 kDa; (II) 97.4–66.2 kDa; (III) 66.2–45.0 kDa; (IV) 45.0–36.0 kDa; (V) 24.0–19.7 kDa; (VI) 14.4–6.5 kDa, respectively. The results show that the protein contents of groups I, II, and V are negatively correlated to peak force and Hunter b value of deep-fried gluten balls, but positively correlated to Hunter L value and sensory evaluation score of appearance. The above results reveal that the high-molecular weight glutenin subunits, ω-gliadins, and albumins/globulins of wheat flour have a profound effect on the quality of deep-fried gluten balls.     

Use of heat-moisture treated maize starch to modify the properties of wheat flour and the quality of noodles

Waxy, normal and high-amylose maize starches were subjected to heat-moisture treatment (HMT) and then added to wheat flour (WF) in different ratios (1%, 5% and 10%). The properties of blends and their cooked noodles were studied to investigate the effects of HMT starches. The incorporation of HMT starch in WF led to an increase in swelling power, peak viscosity and breakdown and to a decrease in setback, thus inhibiting retrogradation, hence enhancing resultant noodle softness. Compared to the same addition ratio of native starch to WF, HMT starch led to higher tensile strength and extensibility in resultant noodles. WF with added HMT starch had higher resistant starch than with native starch. This study showed that addition of HMT maize starch has potential to bring nutritional benefits. However, it is necessary to select the proper blending ratio and amylose content of starch to add, in consideration of its effect on noodle quality.     

Relationships between storage protein composition,protein content,growing season and flour quality of bread wheat

The storage protein composition from the Glu‐1, Glu‐3 and Gli‐1 loci encoding high and low molecular weight glutenin subunits (HMW‐GS and LMW‐GS) and gliadins, respectively, was determined on 30 wheat (T aestivum L) genotypes from three growing seasons. The gliadins and the LMW‐GS were identified as gliadin/LMW‐GS pairs. All samples were analysed by two one‐dimensional electrophoretic techniques, and selected samples were also subjected to two‐dimensional electrophoretic separation. Different statistical/data‐analytical techniques were evaluated in the study of how the presence or absence of the protein alleles, the protein content and the growing seasons are related to flour quality. The year of growth had a large impact on mixograph peak time. When predicting mixograph peak time from the presence or absence of significant proteins and the year of growth, 70% of the variability in mixograph peak time could be explained, whereas only 49% of the variability could be explained when the year of growth was deleted from the model. Protein had no effect on mixograph peak time as expected, and the well‐known positive effect of HMW‐GS 5 + 10, and the negative effects of 2 + 12 and 6 + 8 was observed. Furthermore, some of the gliadin/LMW‐GS combinations influenced mixograph peak time significantly. The gliadin/LMW‐GS at the combined Gli‐A1, Glu‐A3 loci b; ?? was positively related to mixograph peak time, whereas ??; ?? and a;a was negatively related. Although the LMW‐GS component ?? of the alleles b; ?? and ??; ?? alleles appear similar on one‐dimensional gels, two‐dimensional separation of selected samples may suggest that the ?? components in these alleles are different proteins. Cross‐validated partial least squares regression combined with empirical uncertainty estimates (jack‐knifing) of the parameters estimated in the model, gave similar results to ANOVA in identifying quality related protein alleles. The applicability of the multivariate approach in proteomics is, however, much wider. Copyright © 2004 Society of Chemical Industry     

面粉品质与面条品质的关系探讨

从面粉的组成成分及微生物指标入手,对面粉品质与面条制品品质的关系进行了分析和讨论,综述了近年来国内外在优质面条用粉方面的研究进展,以期为面条生产者正确选用面粉品种及改善产品质量提供参考。     

Specific weight and wheat quality

UK winter and spring wheats were studied to establish correlations between specific weight and flour yield. In general, correlations were poor and could not be used for predicting flour yield from specific weight. Specific weight/flour yield relationships are influenced by year, growing site, variety and endosperm texture. The moisture content and moisture history of wheat influences its specific weight, and no universal factor can be applied to correct specific weight results to a fixed moisture basis. Individual wheats exhibit their own correction factors and these are different for wheats that have been dried or damped. 1000 kernel weight was not found to be a suitable alternative to specific weight for flour yield prediction.     

The effect of aphid infection and cultivar on the protein content governing baking quality of wheat flour

BACKGROUND: Aphids cause both quantitative and qualitative yield losses in cereals. Aphid feeding resulted in a significant decrease in gliadin/glutenin ratio in soft‐kernel wheat. Effect of aphid feeding on hard‐kernel wheat was examined. RESULTS: Plants of two different hard‐wheat cultivars were artificially infected by two aphid species: Sitobion avenae and Diuraphis noxia. Three different levels of caging regulated aphid density. Aphid density was highest in the cages, followed by open cages and lowest under no‐cage conditions. Numbers of D. noxia were generally higher compared to those of S. avenae. There was no significant difference in head length, mean kernel number/head, mean kernel mass/head or mean individual kernel mass between the two cultivars. Glutenin, gliadin and total protein content was analysed using size‐exclusion HPLC. Quality parameters of wheat flour were significantly different between the two cultivars. Gliadin content, total protein content and gliadin/glutenin ratio were significantly higher in Mv Magdaléna compared to Mv Magvas regardless of the level of caging and infestation, while glutenin content of uninfected Mv Magvas was significantly higher than that of Mv Magdaléna in the open cages. Aphid feeding did not induce any significant reduction in the gliadin, total protein content and gliadin/glutenin ratio of the examined hard wheat cultivars. CONCLUSION: Individual kernel mass reduction is the major factor in yield loss caused by aphids. Aphid feeding did not change the protein structure of hard‐kernel wheat. Copyright © 2007 Society of Chemical Industry     

小麦及其面粉品质对馒头品质的影响

综合分析了小麦与面粉的蛋白质品质、淀粉品质、酶、脂类物质等对馒头品质的影响。     

Use of response surface methodology to investigate the effects of processing conditions on sourdough wheat bread quality

Response surface methodology was used to investigate the influence of three factors, sourdough fermentation time, proof time and amount of yeast addition on the quality of sourdough wheat bread. Each predictor variable was tested at five levels. Sourdough fermentation times were 5, 11, 20, 29 and 35 h, yeast addition rates were 0.05, 0.75, 1.77, 2.80 and 3.50% (flour weight basis) and proof times were 16, 40, 75, 110 and 134 min. The performance of two different starter culture types, a mixed strain starter culture called Böcker Reinzucht–Sauerteig Weizen and a single strain starter culture of Lactobacillus brevis, was compared by separately completing the experimental design for each. Independently non-acidified control bread was prepared. A range of loaf quality parameters was determined including pH, total titratable acidity, loaf height, specific volume, crumb mean cell area and crumb hardness. Overall breads with better specific volume values were achieved with the use of sourdough relative to the control. Results indicated that maximum loaf specific volume was achieved when L. brevis sourdough was used particularly when it was used in conjunction with a high rate of yeast. Given a lower rate of yeast addition however, the mixed strain starter culture yielded better bread.     

Impact of the fungal protease produced by Fusarium culmorum on the protein quality and breadmaking properties of winter wheat

Samples artificially infected by Fusarium culmorum were analyzed to assess the effects of Fusarium infection on the protein quality of winter wheat (Triticum aestivum L.). The Fusarium infection did not noticeably influence either the crude protein content or the water absorption ability of the wheat flour. The protease activity found in the wheat flour was inversely correlated to the sedimentation value. In contrast, it was positively correlated to both the free amino acid content and the degree of infection as expressed in Fusarium protein equivalents (FPE) quantified by an enzyme-linked immunosorbent assay. A distinct reduction in the content of both total glutenin and high molecular weight glutenin subunits was detected in the seriously infected samples (FPE>20 µg g^–1). The infection with Fusarium impaired the dough quality and led to a deformed loaf shape. The fungal protease was active over both a wide range of temperatures (from 10 to 100 °C) and a wide range of pH values (from 4.5 to 8.5). The maximum protease activity was displayed at 50 °C in the pH range 6.0–8.0. This property indicates that the protease produced by F. culmorum may impair storage proteins throughout all the processing procedures associated with wheat flour, thereby causing weak dough properties and, consequently, unsatisfactory bread quality.