大豆蛋白结构与功能的关系

综述了基因重组技术在揭示大豆球蛋白和β-伴球蛋白的结构与功能关系方面的研究进展.通过对β-伴球蛋白组成亚基(α,α'和β)和α,α'亚基核心区域的功能性质相比较发现,亚基核心区域决定着热稳定性和表面疏水性;α,α'亚基的外延区域决定着蛋白质的溶解度和乳化能力,碳水化合物部分抑制热诱导聚集体的形成.对不同方式改性的大豆球蛋白前体(A1aB1b)的功能性质研究表明,影响凝胶和乳化性能的结构因素明显不同,蛋白C-末端区域的疏水性影响其乳化能力的高低,而游离SH基团的拓扑学结构则与热诱导凝胶的形成有着密切的关系.     

发芽对大豆蛋白凝胶性质的影响

研究了发芽大豆蛋白质凝胶性质的变化。采用碱提酸沉法制备大豆分离蛋白(SPI),以葡萄糖酸-δ-内酯(GDL)为凝固剂制备大豆蛋白凝胶,系统研究了不同芽长大豆蛋白凝胶强度的变化。通过SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)图谱分析了发芽过程中SPI的变化及其对大豆凝胶强度的影响。结果发现:SPI中7S球蛋白的α'、α亚基和11S球蛋白的酸性亚基A3、A发芽时发生明显降解,但11S球蛋白各亚基在发芽初期变化小,利于大豆蛋白质分子之间形成网络结构使凝胶强度增强。随着发芽时间的延长,11S球蛋白也部分发生降解,凝胶强度下降。     

大豆过敏原在低盐固态酱油酿造过程中的降解规律

为研发低致敏酱油,探究了低盐固态酱油酿造过程中大豆蛋白致敏原的变化规律。在建立实验室的模拟低盐固态酱油酿造的基础上,采集大豆未经处理、高压灭菌(121 ℃,8 min)、制曲阶段(44 h)、发酵阶段(30 d)、灭菌前和灭菌后等样品,利用聚丙烯酰胺凝胶电泳法(SDS-PAGE)测定酿造过程中蛋白的组成变化,用兔抗大豆多克隆抗体进行酶联免疫试验和免疫印迹实验分析发酵过程中大豆致敏原抗原性变化,用过敏病人血清进行酶联免疫试验测定大豆致敏原过敏原性变化。结果表明,经高压蒸煮、制曲、发酵和加热灭菌后,原料中的大豆蛋白条带减少或消失,其中制曲变化的最大。β-伴大豆球蛋白的α、α'亚基和大豆球蛋白的酸性亚基分别在制曲阶段开始降解,β-伴大豆球蛋白的β亚基及大豆球蛋白酸性亚基在制曲之后消失,大豆球蛋白的碱性亚基在整个酿造阶段变化不大。免疫印迹结果显示相同的结果,酿造过程中大豆过敏原的过敏性和抗原性逐渐降低,在发酵30 d后的生酱油中仍能在检测到大豆球蛋白,在灭菌后也没有完全降解,但是这些残留的大豆致敏原没有检测到IgE结合能力。酶联免疫试验结果表明,和原材料大豆相比,样品中的抗原性在经过4个酿造阶段高压蒸煮、制曲、发酵和加热灭菌之后分别下降了8.13%、39.00%、69.10%和87.06%,过敏原性分别下降了8.92%、71.66%、92.26%、98.45%。在酱油酿造过程中大豆致敏原逐步降解,制曲阶段对大豆致敏原的降解最大。酱油中仍残留有大豆球蛋白,但是没有检测残留蛋白的致敏性。     

加热联合酶解大豆7S蛋白的分子结构及抗原性研究

选用不同加热预处理条件、不同蛋白酶处理大豆7S蛋白,SDS-PAGE考察酶解后大豆7S蛋白的降解情况,间接竞争ELISA法考察酶解物的抗原性。结果表明:加热预处理联合酶解可显著增大β-伴大豆球蛋白的降解程度,β亚基消化程度得到极大提升,α亚基、α'亚基几乎完全被降解,在相同酶解时间下,胰蛋白酶的酶解速度快于胃蛋白酶;加热预处理联合酶解大幅降低了β-伴大豆球蛋白的抗原性,胰蛋白酶的效果优于胃蛋白酶,经80℃加热10 min预处理再经胰蛋白酶处理,大豆7S蛋白的抗原性降低了79.99%,而胃蛋白酶最优条件下最多仅降低50.4%; SDSPAGE结果表明,胃蛋白酶、胰蛋白酶酶解物中出现了抗消化肽段,经过质谱鉴定,均来自于β-伴大豆球蛋白的α亚基。     

极端pH处理对大豆分离蛋白、β-伴大豆球蛋白、大豆球蛋白结构和功能特性的影响

为丰富大豆蛋白柔性改性技术,采用极端pH条件(pH 1,2,3,4,10,11,12,13)处理大豆分离蛋白(SPI)、β-伴大豆球蛋白(7S)和大豆球蛋白(11S)。通过对SPI、7S和11S蛋白进行凝胶电泳分析、氨基分析、巯基分析和色氨酸荧光分析,并测定大豆蛋白表面疏水性、溶解性、乳化性和起泡性,探讨极端pH处理对SPI、7S和11S结构和性质的影响。结果表明:极端pH处理可导致SPI、7S和11S游离氨基和内源色氨酸荧光强度增加,蛋白表面疏水性提高,三级结构部分展开。此外,极端pH处理可诱导SPI与11S亚基部分解离,而对7S亚基影响较小。极端pH处理能够提高SPI、7S和11S蛋白溶解性、乳化性和起泡性。11S球蛋白可能是SPI结构变化和功能特性改善的主要贡献者。由此可见,极端酸碱处理通过诱导大豆蛋白高级结构的展开,改善其功能特性。     

微生物发酵对豆粕抗原性的影响

探讨了微生物发酵对豆粕抗原性的影响。选用植物乳杆菌、干酪乳杆菌、枯草芽孢杆菌、地衣芽孢杆菌和米曲霉这5种菌株,在液态和固态条件下分别发酵豆粕12 h,对发酵产物进行抗原性测定。结果表明:豆粕经这5种菌株发酵后,粗蛋白含量均有所提高,其中枯草芽孢杆菌在固态发酵时降解豆粕抗原蛋白和降低豆粕抗原性的效果优于其它菌株,此时,豆粕蛋白水解度为4.89%,必需氨基酸含量为193.51mg/g。SDS-PAGE显示发酵豆粕中β-伴大豆球蛋白的α’和α亚基消失,β亚基条带和大豆球蛋白的酸性亚基条带密度减弱,同时大豆球蛋白与β-伴大豆球蛋白的抗原性降低率分别为20.62%和50.12%。     

琥珀酰化提高大豆分离蛋白乳化性的研究

为了提高大豆分离蛋白(SPI)的乳化性,采用琥珀酸酐对大豆分离蛋白进行酰化改性。系统研究了SPI质量分数、琥珀酸酐用量和反应温度对大豆分离蛋白乳化性的影响,建立以上3因素与乳化活性和乳化稳定性关系的数学模型,并利用响应面法优化出大豆分离蛋白琥珀酰化的适宜条件:SPI质量分数6.5%、反应温度49℃、琥珀酸酐添加量11.5%。该条件下制备的琥珀酰化蛋白的乳化活性和乳化稳定性与未改性的大豆分离蛋白相比较,分别提高了2.98倍和4.86倍。     

富硒发芽对大豆蛋白凝胶性质的影响

以10 mg/L Na2SeO3溶液浸泡的大豆为材料,采用碱提酸沉法制备大豆分离蛋白(soybean protein isolate,SPI),以葡萄糖酸-δ-内酯(GDL)为凝固剂制备大豆蛋白凝胶,系统研究了富硒处理及发芽时长对大豆蛋白凝胶性质的影响。结果发现:发芽48 h内大豆GDL凝胶与SPI凝胶的硬度快速下降,分别由25.25 g和27.73 g降至10.77 g和13.37 g,持水性从61.42%和62.64%分别降至51.55%和55.54%。SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)图谱显示,富硒大豆与对照SPI谱带变化基本一致,其中7S球蛋白的β亚基与11S球蛋白的碱性亚基B较稳定,而7S球蛋白的α'亚基和α亚基与11S球蛋白的酸性亚基A3和A则被内源蛋白酶逐渐降解为相对分子质量较小的组成,从而影响发芽大豆凝胶性质。而富硒处理对发芽大豆蛋白凝胶性质影响较小。     

燕麦β-葡聚糖/大豆分离蛋白混合体系的乳化性能研究

为了扩大燕麦β-葡聚糖(OG)在食品中的应用,以粉末状的燕麦β-葡聚糖(OG)和大豆分离蛋白(SPI)为原料,研究了溶液状态下两者混合体系的质量分数、OG/SPI配比、温度和pH值对溶液乳化性能的影响,通过单因素及正交试验优化组合.结果表明,在质量分数为4%,OG/SPI配比为3:1,pH=8.5,温度为60℃时混合体系具有较好的乳化性能;两者的混合能提高乳化性能.     

α'亚基对大豆分离蛋白微观形态及水溶液特性的影响

以东农47和α'蛋白亚基缺失型大豆为原料提取大豆分离蛋白(soy protein isolates,SPI),通过十二烷基磺酸钠聚丙烯酰胺凝胶电泳(sodium dodecyl sulfonate polyacrylamide gel electrophore-sis,SDS-PAGE)技术确定其亚基缺失型,然后对微观...     

正交试验优化低钠火腿肠生产的复合配比

通过添加钠盐替代物开发低钠肉制品选用氯化钾、氯化钙部分替代氯化钠添加到肉制品中,并加入大豆分离蛋白,通过单因素与正交试验,研究生产低钠火腿肠的最佳复合配比.结果显示:替代量分别为28％和8％的氯化钾、氯化钙作为复合替代盐,并添加1.5％的大豆分离蛋白制做的火腿肠品质最好.     

添加不同非肉蛋白对乳化肠品质特性的影响

研究添加3种非肉蛋白(蛋清蛋白、乳清蛋白和大豆蛋白)对乳化肠的质构、颜色、感官和微观结构的影响。结果表明：在这3种蛋白中,添加蛋清分离蛋白所获得乳化肠产品的品质好于乳清分离蛋白和大豆分离蛋白;在低脂肠中添加蛋清分离蛋白比在高脂肠中添加时硬度、胶黏性明显增加(P＜0.05);在高脂肠中添加乳清分离蛋白比在低脂肠中添加时胶黏性明显增加(P＜0.05)。添加不同的分离蛋白对感官评定影响差异不显著(P＞0.05)。     

Studies on emulsion-type buffalo meat sausages incorporating skeletal and offal meat with different levels of pork fat

Ready-to-eat emulsion-type buffalo meat sausages were developed by using a combination of 80% meat components with 20% pork back fat. The meat components were constituted of 70 parts buffalo skeletal meat and 30 parts offal meat (rumen meat and heart meat in equal proportions). The emulsion stability, cooking losses of emulsions and sausages, composition of cooked sausages, eating quality of sausages and the microscopic characteristics of the raw emulsion and cooked sausages were studied. The light microscope micrograph of the raw emulsion showed uniformly well distributed fat globules embedded in a dense protein gel. The cooked emulsion also showed uniformly sized fat globules well distributed in a fine, compact, coagulated protein gel, which retained their original spherical shape. Good quality emulsion-type sausages could be produced having a high emulsion stability (0·87 ± 0·07 ml fat release/100 g emulsion); a low emulsion cooking loss (9·60 ± 0·60%) and a low sausage cooking loss (8·83 ± 0·48%). The overall acceptability of sausages was also high.     

Effect of replacing pork backfat with olive oil on processing and quality characteristics of fermented sausages

Five types of fermented sausages were manufactured by traditional methods as follows: (i) one control (C) using 24% beef meat, 43% pork meat and 33% pork backfat; (ii) two L treatments by replacing 10% and 20%, respectively of pork backfat with liquid olive oil; and (iii) two E treatments by replacing 10% and 20%, respectively of pork backfat with olive oil incorporated as pre-emulsified fat (PEF) with soy protein isolate (SPI). There were no differences (p > 0.05) between treatments relating to pH, brine content, lactic acid bacteria and micrococci and staphylococci count, redness (a (?)) and chemical composition. The L and E treatments had higher lightness and yellowness values than the control. The L treatments had lower (p < 0.05) weight losses and higher (p < 0.05) TBA values and were softer (p < 0.05) than the control. The E treatments had higher (p < 0.05; weight losses, lower (p < 0.05) TBA values and similar hardness to the control. The L sausages had an unacceptable appearance. The E sausages had equally good appearance as well as firmness and odour and taste as the control. It is concluded up to 20% of pork backfat can be replaced with olive oil as PEF with SPI. In preliminary experiments, where 30% pork backfat was replaced with olive oil as PEF with SPI, the product was unacceptable.     

Extrusion for Producing Low-fat Pork and its Use in Sausage as Affected by Soy Protein Isolate

Low-fat pork was produced at extrusion temperatures (ET) of 25, 32.2,43.3,54.4, or 65.6°C with addition of soy protein isolate (SPI) at 0,1.5, or 3% and evaluated by measuring chemical and physical properties of low-fat pork sausage links. ET and SPI addition influenced moisture retention and fat reduction. The highest ET(65.5°C) gave the highest fat reduction in extrudates. TBARS decreased as ET and SPI increased. Extrudates at higher ET made darker and redder sausages. The hardness value of the control was not different from that of sausages from 65.6°C ET extrudates. The fat-reduced sausages were more springy and cohesive than the control. Depending on fat reduction, twin-screw extrusion influenced sausage color, texture, and lipid oxidation. The sausage links from 65.6°C ET extrudates with 1.5% SPI had the lowest fat, lowest TBARS, least cooking loss and were not different in hardness from control high-fat sausages.     

Quality properties of sausage made with gamma-irradiated natural pork and lamb casing

Quality properties in emulsion-type sausage stuffed into irradiated natural casing were studied. Fresh salted and semidried natural pork and lamb casing was washed and irradiated at 0, 3, and 5 kGy by gamma-ray and emulsion-type pork sausage (Brattella Weiss Wurst) was manufactured. The sausage was stored in a 4°C refrigerator. The numbers of total aerobic bacteria, Enterococcus and coliform bacteria in the irradiated natural casing or sausage prepared from irradiated casing were significantly decreased or eliminated compared to those of the nonirradiated control. The D(10) values of total aerobic bacteria of the pork and lamb casing were 0.87 and 0.92 kGy, respectively. The vacuum-packaged sausages made with irradiated casings had a higher 2-thiobarbituric acid reactive substances value than that of the nonirradiated controls only at 5-day with pork casing and at 10-day with lamb casing. The total working force for shear of the sausages was decreased in both irradiated casings but the sensory evaluation showed no difference. Therefore, the gamma irradiation was a useful technique to sanitize the natural pork and lamb casings and to extend shelf-life, primarily microbial quality, of the sausage made with natural casings.     

Nanofibrillated Cellulose as Functional Ingredient in Emulsion-Type Meat Products

The objective of this work was to introduce nanofibrillated cellulose (NFC) in the formulation of cooked emulsion-type sausages with the aim of assessing its feasibility to assume the role or compensate the lack of some conventional functional ingredients, such as polyphosphates, maize starch, and sodium caseinate. For this aim, sausages based on standard commercial formula (control) including all three ingredients and sausages containing 0.5% NFC instead of phosphates and starch (NFC-1) or instead of phosphates, starch, and sodium caseinate (NFC-2) were produced and characterized. In NFC-1 samples, 0.5% nanofibrillated cellulose succeeds in replacing 0.5% polyphosphates and 1% starch without significantly altering the composition, nor negatively affecting the fat and water retention properties, neither of the raw batter or the cooked sausages. However, less stable meat batters and sausages with significantly reduced water-holding capacity were obtained when 1.5% sodium caseinate, in addition to phosphates and starch, was also removed (NFC-2). Nevertheless, results were hopeful enough to encourage further optimization studies, using several NFC concentrations and/or cellulose with different nanofibrillation degrees, in order to clarify whether it is possible to successfully replace also non-meat proteins in cooked emulsion-type sausages.     

猪肉肠中亚麻籽胶、大豆分离蛋白、酪蛋白的相互作用研究

研究猪肉肠中亚麻籽胶、大豆分离蛋白和酪蛋白的相互作用。采用析因试验设计,在猪肉肠加工过程中,同时添加不同质量分数的亚麻籽胶、大豆分离蛋白和酪蛋白,分析上述添加物对产品保水性、保油性的影响。结果显示：添加亚麻籽胶对猪肉肠在60℃条件下烘20min的保水能力有极显著的影响(P＜0.01),然而,亚麻籽胶对猪肉肠在60℃条件下烘40min的保水能力没有显著的影响(P＞0.05)。酪蛋白的添加对猪肉肠在60℃条件下烘20min和40min的保水能力有显著的影响(P＜0.05)。保水能力上,从高到低依次为：酪蛋白、亚麻籽胶、大豆分离蛋白。亚麻籽胶的添加显著地影响了用乙醚浸提20、40、60min猪肉肠的保油性(P＜0.05),大豆分离蛋白和酪蛋白也有类似结果。大豆分离蛋白对猪肉肠用乙醚浸提60min的保油性有极显著性影响(P＜0.01),并且,亚麻籽胶与大豆分离蛋白有显著的交互作用(P＜0.05)。在保油能力上,大豆分离蛋白强于酪蛋白。     

The influence of added whey protein/carrageenan gels and tapioca starch on the textural properties of low fat pork sausages

Response surface methodology (RSM) was used for simultaneous analysis of the effects of added high gelling 35% whey protein concentrate, (0-12%)/carrageenan (0-3%) preformed gels with dry addition of tapioca starch (0-3%), on the physical, textural and sensory characteristics of low-fat fresh pork sausages. Experimental design allowed for evaluation of potential interactive effects between these ingredients. Sausages were evaluated for cookloss, water holding capacity (WHC), mechanical texture and sensory attributes. Analysis of variance of regression models showed that ingredient blends had a significant influence on cookloss (p<0.01), WHC (p<0.05), purgeloss (p<0.05), texture (p<0.001) and the sensory attributes of flavour intensity (p<0.05), overall flavour (p<0.01) and juiciness (p<0.001). Addition of preformed gel and tapioca starch had a significant (p<0.01) negative interactive effect on % cook loss, and gave a significant (p<0.05) positive linear effect for mechanical textural values. Increasing levels of preformed gel blends with tapioca starch resulted in a general decrease in flavour intensity and overall flavour scores. Mixed gels containing high gelling 35% (protein) whey protein concentrate (8%) and carrageenan (1.5%), with dry addition of tapioca starch (3%) produced final low-fat (<3% fat) pork sausages with similar characteristics to those of full-fat (20% fat) controls.     

Optimization of textural properties of reduced-fat and reduced-salt emulsion-type sausages treated with high pressure using a response surface methodology

This study optimized the high pressure conditions for development of a reduced fat sausage. A three-factor-three-level Box–Behnken design was adopted to study the simultaneous effects of one compositional variable (15, 20 and 25% fat content) and two processing variables (150, 200 and 250 MPa high pressure, along with 5, 6 and 7 min high pressure treatment time) on firmness of emulsion-type sausages. Analysis of variance (ANOVA) was performed to evaluate the potential interactive and quadratic effects between these variables. The results revealed that, the optimum processing conditions for an optimum gel setting were 22.19% fat content, 197.30 MPa high pressure and 5.92 min pressure treatment time. The adequacy of the model equation for predicting the optimum response values was effectively verified. In conclusion, the emulsion-type meat sausages using a novel high pressure based processing method were preferred for their improved textural properties and reduced fat content.Industrial relevanceFor health reasons, there is a need to reduce fat content of processed meat products. This study developed a novel processing method using high pressure to produce emulsion-type meat sausages with reduced-fat, with improved functional qualities, including objective appearance, textural properties and sensory evaluation. Importantly, this was achieved with a model, mainly based on prediction of the firmness of the pressure treated sausages with reduced fat contents.