储藏时间对大豆蛋白和谷朊粉的结构及功能特性的影响

为了探究储藏过程中组织化植物蛋白原料性质的变化，本研究对大豆分离蛋白（SPI）、大豆浓缩蛋白（SPC）和谷朊粉（WG）三种主要蛋白原料进行加速储藏实验，测定储藏过程中原料的羰基含量、巯基及二硫键含量、表面疏水性、溶解度、持水性、持油性和吸水率的变化。结果表明：到储藏期结束，SPI和SPC羰基含量大约分别增加144%和130%，游离巯基含量则在加速储藏15天显著降低，大约分别减少62%和67%；WG的羰基含量大约增加45%，游离巯基含量在储藏过程中缓慢下降，大约减少15%。随着储藏的进行，三种蛋白的二硫键含量和表面疏水性均先增加后降低，功能特性上SPI和SPC的溶解度分别从88.67%、78.69%降低到42.36%、25.22%，而WG溶解度却从6.78%增大到8.48%；三种蛋白质持水性均降低，其中SPC持水性下降程度大，达30%，WG吸水率没有显著性变化；SPI和WG的持油性先升高后降低，SPC的持油性则在加速储藏75天时出现显著性下降。这说明储藏期内蛋白质发生氧化反应，导致蛋白结构和功能特性发生变化，最终将影响组织化蛋白的品质特性。     

不同频率超声对鲢鱼肌原纤维蛋白结构的影响

以鲢鱼为原料,采用单频、双频和三频超声分别处理鲢鱼肌原纤维蛋白,研究不同频率超声处理对肌原纤维蛋白表面疏水性和表面巯基含量的影响。结果表明:经不同超声处理后,随着超声时间的延长,肌原纤维蛋白的表面疏水性和表面巯基含量均呈现先增大后减小的趋势。单频和三频超声在分别处理肌原纤维蛋白15 min和10 min后,其表面疏水性和表面巯基含量达到最高值。与未超声处理蛋白的表面疏水性相比,80 kHz超声处理15 min后的蛋白表面疏水性提高了56.88%,三频超声处理10 min的蛋白表面疏水性提高了65.34%。与未超声处理蛋白的表面巯基含量相比,80 kHz超声处理15 min后的蛋白表面巯基含量提高了11.19%,三频超声处理10 min的蛋白表面巯基含量提高了13.32%。双频超声对蛋白表面疏水性和表面巯基的影响作用介于单频和三频超声处理的之间。     

大黄鱼鱼卵磷脂对面团流变学和面包感官品质的影响

目的 探究大黄鱼鱼卵磷脂对面团流变学和面包感官品质的影响。方法 以小麦面包为对象,面团动态流变性及面包比容、色泽和质构为评价指标,分析不同大黄鱼鱼卵磷脂添加量（0%、0.2%、0.6和1.0%）对面包外观、感官品质和质构的影响,将添加大豆磷脂（0.6%）的面团和面包作为对照组。结果 随着提高大黄鱼鱼卵磷脂的添加量,面包的硬度、咀嚼性持续增大,弹性、粘聚性逐渐降低。 当鱼卵磷脂添加量为0.2%时,能够显著改善面包的质构,而且能够增大面包的比容,生产出的磷脂-小麦面包口感较好,入口软糯。与普通小麦面包相比,其面包蓬松稳定,具有较好黏弹性。结论 添加大黄鱼鱼卵磷脂比大豆磷脂更能显著改善面包感官品质。     

面包制作过程中戊聚糖酶的作用机理

研究了戊聚糖酶对面包品质的影响.加酶面包的体积明显增加,在适宜加酶量下,面包综合品质较佳.加酶面团中可溶性戊聚糖含量显著增加,但加酶过量可导致面团中水可提取的阿拉伯木聚糖(WEAX)降解程度加剧.未加酶面团较原料面粉中的可溶性戊聚糖含量略有增加,WEAX亦有部分降解,但作用程度远低于加酶样品.适量戊聚糖酶对面包品质的改良作用的关键在于产生大量的相对分子质量适宜的WEAX.     

冻藏时间对猪肉中肌原纤维蛋白氧化程度的影响

对在-18℃下贮藏不同时间(0,1,4,8,12周)的原料猪肉进行肌原纤维蛋白提取,对其羰基、总巯基、自由氨基、表面疏水性和内源性色氨酸荧光进行测定。结果表明:随着贮藏时间的延长,羰基含量显著升高(P<0.05),总巯基、自由氨基、表面疏水性和内源性色氨酸荧光含量整体上呈下降趋势(P<0.05);贮藏时间与羰基、总巯基、自由氨基或表面疏水性之间具有显著相关性。因此,即便在冻藏条件下,肌原纤维蛋白也会出现一定程度的氧化,导致原料肉品质下降。     

食盐腌制对鸡肉品质、肌原纤维蛋白结构和功能特性的影响

为探究食盐浓度对冷藏腌制过程中鸡肉品质和肌原纤维蛋白的影响,将鸡肉置于不同浓度（0%、1.6%、3.2%、4.8%、6.4%、8.0%）的食盐腌制液中,进行不同时间（0.2、1、2、3、4 d）的冷藏腌制后,测定鸡肉的水分含量、持水性以及肌原纤维蛋白的溶解度、表面疏水性、羰基、巯基、二聚酪氨酸含量等。结果表明：经过不同浓度食盐液的腌制,鸡肉的持水性和肌原纤维蛋白表面疏水性发生变化,随着腌制时间的延长羰基含量和二聚酪氨酸含量增大,肌原纤维蛋白的溶解度、热稳定性、巯基含量降低,部分α-螺旋转化为β-折叠。随着食盐液浓度增大羰基和二聚酪氨酸含量先增加后减小,巯基含量不断增大,并且食盐液浓度范围为3.2%～4.8%时肌原纤维蛋白各特性指标变化较大。综上,食盐腌制能促使鸡肉肌原纤维蛋白结构和功能发生改变,此研究结果可为控制腌制过程中鸡肉品质变化和其肌原纤维蛋白氧化提供理论依据。     

双循环高静压对鱿鱼原肌球蛋白二、三级结构的影响

为研究双循环高静压处理对鱿鱼原肌球蛋白结构的影响,通过圆二色谱、自由巯基含量和表面疏水性分析原肌球蛋白的二级和三级结构变化。与对照组相比,双循环高静压(200,400 MPa和600 MPa,20 min)使α螺旋降低50%,β螺旋增加10%,随机结构增加40%。双循环高静压降低了蛋白自由巯基含量,增加了表面疏水性,在600 MPa下自由巯基含量减少高达35%,表面疏水性增加47%。高静压引起的原肌球蛋白二、三级结构变化与蛋白致敏性降低具有显著的相关性(P0.01)。研究表明,双循环高静压能够有效改变原肌球蛋白结构,进而降低致敏性。     

低温冷冻条件对大豆分离蛋白分散液表面疏水性及二硫键的影响

通过大豆分离蛋白（soybean protein isolate,SPI）冷冻前后结构的变化,研究了低温冷冻条件（SPI添加量、冷冻温度、冷冻时间）对SPI结构（巯基、二硫键及表面疏水性）的影响。实验发现在冷冻条件下随着SPI添加量的降低,游离巯基和二硫键逐渐减少、暴露巯基与表面疏水性先增加后减小;随着冷冻温度降低和冷冻时间延长,SPI的游离巯基、二硫键含量及表面疏水性逐渐减少。经过冷冻处理的SPI会有一定程度的变性,在不太低的冷冻温度下游离巯基含量明显大于未冷冻SPI,且在冷冻过程中SPI大部分的分子内二硫键转化为分子间二硫键。     

谷氨酰胺转氨酶对藜麦-小麦面团及面包品质的影响

为开发烘焙品质较好的藜麦-小麦粉面包,利用谷氨酰胺转氨酶对其进行改良。从藜麦-小麦粉的粉质参数、糊化特性、面团质构、面包烘焙品质及老化特性等方面研究谷氨酰胺转氨酶(transglutaminase,TGase)对藜麦-小麦粉品质的影响,综合评价TGase对藜麦-小麦粉面团、面包品质的影响。结果表明,TGase增大混粉体系的吸水率、延长稳定时间。增大混合粉体系的糊化黏度、抑制体系的老化及回生。随着TGase的添加量的增大,面团硬度、弹性、黏聚性增大,当超过1.0%时,变化不显著(p>0.05)。面包品质结果表明,TGase的加入改善面包的持气能力,增大比容、感官评分、弹性及黏聚性,降低了面包的硬度,但是高剂量的TGase(>1.0%)会导致交联过度,面包品质降低。老化特性结果表明,TGase的加入使得面包老化程度降低,抑制面包老化。     

高静水压和热处理对荞麦蛋白功能性质的影响

高静水压（high hydrostatic pressure,HHP）处理技术作为一种新型的非热食品加工技术,在食品加工中具有对食物营养和感官品质破坏较小等多种优势。本实验通过HHP处理与传统热处理法（heat treatment,HT）处理荞麦蛋白（buckwheat protein,BWP）,并测定BWP溶解性、起泡性和乳化性等性质,此外通过BWP羰基含量、巯基含量和表面疏水性测定以及傅里叶变换红外光谱分析,研究不同加工处理方式对BWP功能性质的影响。结果表明：随着HHP处理压力的增加,BWP的羰基含量、表面疏水性显著升高（P＜0.05）,而巯基含量显著降低（P＜0.05）;在500 MPa、30 min时,BWP乳化性、起泡性均达到最大值（67.3 m2/g和91.5%）,较空白对照组（未经HHP处理）分别提高33.0%、16.1%,较HT处理组分别提高61.5%、52.8%。傅里叶变换红外光谱结果表明,HHP处理后BWP的α-螺旋和β-折叠相对含量减少,β-转角和无规卷曲相对含量增加。经相关性分析发现,BWP的溶解性、乳化性、起泡性、羰基含量与巯基含量之间均存在相关性。其中,BWP的乳化性与起泡性、表面疏水性呈极显著正相关（P＜0.01）,并且与巯基含量呈极显著负相关（P＜0.01）。综上,HHP处理可以改变BWP的功能性质。可为进一步研究BWP在功能食品的应用提供理论和实验依据。     

Arabinoxylan content and characterisation throughout the bread‐baking process

End‐use quality of wheat (Triticum aestivum L.) is influenced in a variety of ways by nonstarch polysaccharides, especially arabinoxylan (AX). The objective of this study was to track total and water‐extractable AX (TAX and WEAX, respectively) throughout the bread‐baking process, using wholemeal and refined flour. The TAX and WEAX content and the ratio of arabinose: xylose were assessed in flour, mixed dough, proofed dough and the bread loaf, which was separated into crumb, upper crust and bottom crust. Changes in TAX during the baking process differed between the refined flour and wholemeal samples, suggesting a change in the TAX availability which we ascribe to molecular interactions and heat treatment. WEAX content dramatically decreased during baking, suggesting that oxidative cross‐linkages rendered it unextractable. Higher levels of WEAX and lower levels of arabinose substitution were correlated with higher loaf volumes for refined flour among the hard wheat varieties. Having a better understanding of the importance of both WEAX content and arabinose substitution allows for directed breeding efforts towards improved hard wheat varieties for optimum bread baking.     

品质改良剂对复合杂粮面包粉流变学特性的影响

以营养优化后的复配杂粮面包粉为原料,选择谷朊粉、硬脂酰乳酸钠（sodium stearoyl lactylate,SSL）、黄原胶及瓜尔豆胶为品质改良剂,通过单因素试验研究4 种品质改良剂对杂粮面包粉流变学特性的影响,在此基础上通过响应面分析试验,以面团综合得分为响应值,得出复合改良剂的最佳配方为：1 000 g杂粮面包粉（杂粮粉占比34%）为基重,谷朊粉3.77%、SSL 0.35%、黄原胶1.08%、瓜尔豆胶0.35%。各因素对杂粮面包粉综合评分的影响大小为：黄原胶添加量＞谷朊粉添加量＞瓜尔豆胶添加量＞SSL添加量。添加复合改良剂后杂粮面包粉的稳定时间由4.7 min上升到14.2 min,形成时间由3.9 min上升到了13.3 min,粉质指数从56上升到192。复配杂粮面包粉流变学特性有很大程度改善,达到制作杂粮面包的粉质要求。     

发酵麦麸及其面包面团中阿拉伯木聚糖溶解性与酚酸释放研究

将发酵麦麸作为功能配料用于高膳食纤维面包面团制作,采用化学分析、高效液相色谱及离子色谱法分析麦麸发酵、面包制作过程及面包中阿拉伯木聚糖溶解性和酚类化合物释放。结果表明：随着发酵时间延长,麦麸中水溶性阿拉伯木聚糖、游离酚及阿魏酸含量逐渐增加。发酵处理后,麦麸中游离阿拉伯糖、葡萄糖和果糖含量增加,水溶性阿拉伯木聚糖含量显著提高,分支度显著下降（P＜0.05）。面包搅拌、醒发及烘焙过程中,阿拉伯木聚糖不断溶解,酚类化合物持续释放;富含发酵麦麸的面包中水溶性阿拉伯木聚糖含量及分支度更高。模拟肠、胃消化后,富含发酵麦麸的面包中游离酚和阿魏酸含量更高,且吸收效果好。此外,发酵麦麸显著提高了面包的抗氧化活性。     

谷氨酰胺转氨酶对大豆与小麦混合蛋白凝胶性质的影响

研究谷氨酰胺转氨酶（transglutaminase,TG）对大豆和小麦混合蛋白凝胶特性的影响,通过游离巯基含量、表面疏水性、热特性、二级结构和微观结构等测定对混合蛋白凝胶的构象进行了表征。结果显示,当大豆蛋白比例低于45%时,随着大豆蛋白所占比例的增加,凝胶强度显著增强。TG交联混合蛋白凝胶后,其游离巯基减少,热稳定性增强,表面疏水性降低。与TG催化小麦蛋白相比,大豆蛋白添加量为45%的混合蛋白凝胶强度提高了62.74%,β-折叠含量增加了5.701%,游离巯基含量减少了47.48%。     

A survey of water‐extractable arabinopolymers in bread and durum wheat and the effect of water‐extractable arabinoxylan on durum dough rheology and spaghetti cooking quality

BACKGROUND: Information on the variation in water‐extractable arabinopolymers (WEAP) in durum wheat and their impact on pasta quality is limited. A survey of the content of WEAP in selected bread wheat varieties and durum wheat was conducted and the influence of water‐extractable arabinoxylans (WEAX) on dough and spaghetti quality was examined by fortifying low‐WEAP durum semolina with purified WEAX. RESULTS: Bread wheat typically possessed higher levels of WEAP than durum wheat, but the latter had a greater range. Purified WEAX was extracted from bread wheat cultivar Sunlin which possessed a high level of WEAP. The extract was used to fortify semolina (0.125–2% w/w) derived from durum wheat variety Tamaroi (low WEAP). Fortification caused a near linear increase in farinograph water absorption of approximately 12% over the range of addition, leading to dough weakening. Reduced cooked pasta stickiness was observed at all levels of WEAX addition. CONCLUSION: Increased WEAX content may be a means to improve pasta quality by reducing pasta stickiness. Durum wheat showed a wide range of WEAP contents, and this may well be exploited by developing cultivars with elevated WEAP levels. © 2008 Crown in the Right of the State of New South Wales and Society of Chemical Industry.     

A simplified method for extracting water‐extractable arabinoxylans from wheat flour

BACKGROUND: Water‐extractable arabinoxylan (WEAX) is a minor constituent of wheat grain which influences the properties of wheat dough and its end products while conferring numerous health benefits. Consequently, various applications have been proposed for it in foodstuffs. Fortification of food products with pure WEAX extracts represents a simple means to evaluate its effect in these systems. However, rapid methods to isolate relatively pure WEAX are not available. This study aimed to develop a rapid, technically simple means to extract relatively pure WEAX on a small scale. RESULTS: A simplified process was developed to extract WEAX from wheat flour. After heating, flour WEAX was extracted with water and starch was eliminated by digestion with amyloglucosidase. Most of the protein was removed by adsorption to bentonite and precipitation with 65% ethanol. The final product generated by the developed method consisted of 93 ± 4% arabinoxylan. The WEAX yield was 0.43 ± 0.02% (0.43 ± 0.02 g WEAX/100 g of starting flour) which is higher than that of other methods that generate WEAX of similar purity. CONCLUSION: This method provides a technically simple means to perform small‐scale isolation of WEAX that contains no detectable contaminating protein. This attribute renders it a preferred input for studies assessing the impact of WEAX fortification on food product quality. Copyright © 2008 Society of Chemical Industry     

Molecular Oxygen and Reactive Oxygen Species in Bread-making Processes: Scarce,but Nevertheless Important

In bread making, O₂ is consumed by flour constituents, yeast, and, optionally, some additives optimizing dough processing and/or product quality. It plays a major role especially in the oxidation/reduction phenomena in dough, impacting gluten network structure. The O₂ level is about 7.2 mmol/kg dough, of which a significant part stems from wheat flour. We speculate that O₂ is quickly lost to the atmosphere during flour hydration. Later, when the gluten network structure develops, some O₂ is incorporated in dough through mixing-in of air. O₂ is consumed by yeast respiration and in a number of reactions catalyzed by a wide range of enzymes present or added. About 60% of the O₂ consumption in yeastless dough is ascribed to oxidation of fatty acids by wheat lipoxygenase activity. In yeasted dough, about 70% of the O₂ in dough is consumed by yeast and wheat lipoxygenase. This would leave only about 30% for other reactions. The severe competition between endogenous (and added) O₂-consuming systems impacts the gluten network. Moreover, the scarce literature data available suggest that exogenous oxidative enzymes but not those in flour may promote crosslinking of arabinoxylan in yeastless dough. In any case, dough turns anaerobic during the first minutes of fermentation.     

脱皮对不同筋力小麦粉及其馒头品质的影响

对小麦进行适度脱皮,既能去除粗纤维和表面污染物,还能较好的保留微量营养素.以高筋、中筋和低筋小麦为原料,研究4％脱皮率对不同筋力小麦粉及其馒头品质的影响.结果表明,高筋和低筋小麦脱皮后糊化参数均有所提高,而中筋小麦有所下降;脱皮后,高筋、中筋和低筋小麦粉破损淀粉质量分数分别增加了6.0％、2.6％和4.2％;高筋和低筋...     

Wheat Germ Lipoxygenase: Its Effect on Dough Rheology,Microstructure, and Bread Making Quality

Extracted lipoxygenase from defatted wheat germ of commercial bread wheat along with raw and defatted germ were used to study their effect on rheological characteristics of wheat flour dough and bread making quality. The addition of 500 U and 1000 U of lipoxygenase increased the water absorption from 59.5 to 62.3 and 66.7%, respectively. The dough stability increased to 10.5 min, whereas mixing tolerance index values marginally decreased, and the addition of raw or defatted germ did not affect the mixing profile of the wheat flour dough. Breads with lipoxygenase were softer with a lower firmness value of 546 g when compared to the control (594 g) and had brighter crumb as seen in the reduction in ΔE values from 22.34 (control) to 19.04. The addition of gluten along with the lipoxygenase showed a synergistic effect. The specific volume of breads increased to 3.95 cc/g and the firmness values decreased to 538 g. Scanning electron micrographs at different stages of bread processing have shown improvement in the gluten network.