多羟基醇对发酵香肠加工过程中理化性质及感官品质的影响

研究了不同山梨糖醇添加量下,发酵香肠加工过程中主要理化性质及感官品质的变化情况。结果表明山梨糖醇添加量≤8%时,发酵剂产酸能力与对照组无显著差别,而添加量≥10%时,发酵剂产酸能力受到一定程度的抑制;发酵香肠加工过程中,水分活度逐渐降低,山梨糖醇的加入可以增大发酵香肠水分活度的降低幅度;当保持最终产品水分活度为0.85时,添加山梨糖醇组的发酵香肠水分含量均显著高于对照组(p<0.05)。加工过程中发酵香肠非蛋白氮含量、蛋白降解指数和氨基态氮含量逐渐升高;与对照组相比,山梨糖醇添加量≥4%时蛋白降解程度显著降低(p<0.05)。相关性分析表明发酵和烘烤过程中,山梨糖醇添加量分别与PI值和Aw呈极显著负相关,与pH呈极显著正相关(p<0.05)。而感官分析表明不同添加量下产品的滋味和香味并无显著差别,山梨糖醇添加量≥4%时可以改善产品的口感,山梨糖醇添加量4%~8%时产品总体可接受性较高。     

SPI/MC关混可食膜的性能研究

研究了甲基纤维素(MC)对以甘油为增塑剂的大豆分离蛋白(SPI)膜物理性质的影响.结果表明:SPI膜的抗拉强度和表面疏水性随着MC添加量的增加而显著提高(P≤0.05),在添加量为20.0%(w/w,SPI)时相对于对照样分别提高了66.32%和25.39%;断裂伸长率随着MC添加量的增加而先增大后降低,在添加量为10.0%时最大;膜的透光率、水分含量、可溶性干物质总量和水蒸气透过系数随着MC添加量的增加而降低(P≤0.05),在添加量为20.0%时相对于对照样分别降低了41.58%、14.02%、26.55%和20.86%.     

十二烷基磺酸钠对大豆分离蛋白膜性能的影响

本文研究了以甘油为增塑剂时,十二烷基磺酸钠（SDS）对大豆分离蛋白（SPI）膜功能特性的影响。结果表明：SDS可改善SPI膜的功能特性．显著提高了膜的延展性和阻水能力。当膜液中SDS的添加量为SPI的20％时,膜的断裂伸长率最大,为221％,比对照提高了301％;透光率最大,为43．6％,比对照提高了98％;膜的水分含量为22．2％,比对照降低了7．5％;膜的水蒸气透过率为7．8gmm/／m^2 hkPa,比对照降低了23％。但添加SDS也使膜的抗拉强度有所降低,膜的厚度、膨胀率、总可溶性物含量增加。     

十二烷基磺酸钠对大豆分离蛋白膜性能的影响

本文研究了以甘油为增塑剂时,十二烷基磺酸钠（SDS）对大豆分离蛋白（SPI）膜功能特性的影响。结果表明：SDS可改善SPI膜的功能特性．显著提高了膜的延展性和阻水能力。当膜液中SDS的添加量为SPI的20％时,膜的断裂伸长率最大,为221％,比对照提高了301％;透光率最大,为43．6％,比对照提高了98％;膜的水分含量为22．2％,比对照降低了7．5％;膜的水蒸气透过率为7．8gmm/／m^2 hkPa,比对照降低了23％。但添加SDS也使膜的抗拉强度有所降低,膜的厚度、膨胀率、总可溶性物含量增加。     

超微绿茶粉对绿茶面包加工过程中色泽的影响

以超微绿茶粉为原料,研究绿茶面包加工过程中和面、发酵、烘烤3个加工工序关键节点处色泽和茶多酚含量的变化。结果表明,在加工过程中,烘烤工序对色泽变化影响较大;当超微绿茶粉的添加量增加时,L~*、a~*值都显著下降,而b~*值却先显著上升而后缓慢下降,在超微绿茶粉添加量(质量分数)为4%时,b~*值最大。茶多酚含量随超微绿茶粉含量的增加而增加,各个加工工序的进行均造成茶多酚含量的减少,其中烘烤工序对茶多酚含量减少影响最显著。绿茶面包颜色感官评分随着超微绿茶粉添加量的增加呈先上升后下降的趋势,当超微绿茶粉添加量(质量分数)为4%时,评分最高。通过不同方法间的相关性分析,发现色差仪测定与化学方法测定茶多酚含量、感官评定法间相关性较好。     

黄原胶和魔芋胶抑制碱诱导鸭蛋清凝胶的高温液化

本研究分别将黄原胶和魔芋胶添加至鸭蛋清中制备碱诱导凝胶,以探究亲水胶体对凝胶高温液化的抑制作用,结果表明:与对照组相比,添加亲水胶后的蛋清凝胶黏度、储能模量和损耗模量增大明显(p<0.05),褐变强度增加了7.99%和33.21%;当黄原胶和魔芋胶的浓度由0.50%增加至1.50%,凝胶硬度值提高49.60%和119.56%,穿刺强度提高20.59%和78.42%,持水性提高1.02%和9.47%,且添加黄原胶的蛋清凝胶硬度、穿刺强度和持水性均显著大于魔芋胶(p<0.05)。两种胶的浓度均为1.00%时,蛋清凝胶的感官评分最高。两种亲水胶的加入会改变蛋白质的二级结构及凝胶内部的分子间作用力:黄原胶量的增加显著降低了离子相互作用(p<0.05),无规则卷曲减少了41.23%,α-螺旋增加了81.29%;魔芋胶量的增加显著降低了疏水相互作用(p<0.05),β-折叠减少了34.97%,无规则卷曲和α-螺旋分别增加了68.97%和70.37%;氢键和二硫键均随两种胶浓度的增加而增强。综上所述,添加黄原胶和魔芋胶均能抑制碱诱导蛋清凝胶在高温处理过程中的液化现象,且加入黄原胶所形成的凝胶质构特性和持水性优于魔芋胶,而魔芋胶对于凝胶褐变强度的影响大于黄原胶。     

几种食品添加剂对挤压即食食品丙烯酰胺形成的抑制效果研究

以马铃薯-小麦混合粉为原料,通过在挤压膨化即食食品中,添加不同种类、不同浓度的食品添加剂,研究不同添加剂对产品中丙烯酰胺含量的影响。结果表明:海藻糖、大豆多肽、茶多酚、竹叶提取物、氯化钙等食品添加剂的添加对挤压产品中丙烯酰胺含量的影响显著(p<0.05)。其中当氯化钙添加量达到0.5%时,产品中丙烯酰胺含量比对照减少了80%;大豆多肽添加量达到3%以上或竹叶提取物含量达到0.3%时,产物中丙烯酰胺含量对比对照组减少了50%。     

山梨酸钾对魔芋葡甘聚糖/玉米醇溶蛋白复合膜的性能和抑菌效果的影响

本文以魔芋葡甘聚糖和玉米醇溶蛋白为基材,制备了不同山梨酸钾添加量的复合膜,研究了复合膜的理化性能和抑菌效果。结果表明,添加不同含量山梨酸钾对复合膜的膜厚没有显著影响(p0.05),复合膜的水蒸气透过率和透光性随着山梨酸钾添加量的增加而降低。复合膜的断裂伸长率随着山梨酸钾添加量的增加而显著增大(p0.05),当其含量为12%时,复合膜的断裂伸长率为36.02%,是未添加山梨酸钾复合膜的1倍;当添加6%的山梨酸钾时,复合膜的拉伸强度最大,为58.78 MPa。随着山梨酸钾添加量的增加,复合膜对大肠杆菌、金黄色葡萄球菌和蜡样芽孢杆菌的抑菌效果明显增强。当山梨酸钾添加量为12%时,鱼肉在4℃储藏时的货架期可延长4 d。复合膜适合应用在食品保鲜包装。     

紫马铃薯全粉对马芬蛋糕质构性能和感官品质的影响

研究了紫马铃薯全粉添加对马芬蛋糕烘焙损失率、色差、质构性能及感官的影响。结果表明,不同比例混合粉的水溶性及持水性有显著差异(p0.05),马芬蛋糕的烘焙损失率在紫马铃薯全粉添加量小于70%时差异不显著(p0.05),但是当紫马铃薯全粉添加量为90%时,烘焙损失率差异显著(p0.05)。马芬蛋糕的亮度随着紫马铃薯全粉含量增加而显著降低(p0.05)。马芬蛋糕的硬度随着紫马铃薯全粉添加量增加而显著增加(p0.05),在紫马铃薯全粉含量在10%~30%时,其他质构指标变化差异不显著(p0.05);紫马铃薯全粉添加量为10%和30%获得最高分。综上分析,适宜的紫马铃薯全粉添加量为30%。     

青稞全粉与中筋小麦粉复配体系品质特性研究

选用青稞全粉作为研究对象,与中筋小麦粉复配,检测不同添加量青稞全粉的损伤淀粉特性、粉质特性、糊化特性、溶剂保持力,并进行相关性分析。研究表明:随着青稞全粉比例增加,破损淀粉显著增加(P<0.05),且与降落数值呈显著负相关;面团的吸水率呈上升趋势,当青稞全粉添加量为85%时面团的吸水率达到最大值73.10%,吸水率、弱化度显著增加(P<0.05);不同添加量对混合粉稳定时间的影响不显著;峰值黏度、最低黏度、最终黏度、衰减值、回生值显著下降(P<0.05),降落数值与峰值黏度呈极显著正相关;乳酸溶剂保持力SRC显著减少(P<0.05),湿面筋含量和乳酸溶剂保持力SRC呈极显著正相关;碳酸钠溶剂保持力SRC、蔗糖溶剂保持力SRC、水溶剂保持力SRC显著增加(P<0.05),破损淀粉值与碳酸钠溶剂保持力SRC,蔗糖溶剂保持力SRC与吸水率、蛋白质,水溶剂保持力SRC与蛋白质均呈极显著正相关性。     

Effect of solution pH on solubility and some structural properties of soybean protein isolate films

Changes in solubility and molecular properties of protein films obtained from soy protein isolate (SPI) solutions at different pH values (2, 8 and 11) were investigated to study protein behavior during film formation. Proteins retained their native conformation in films at pH 8, but were partially or extensively denatured at pH 11 and 2. Although film protein networks were maintained by the same type of interactions at different pH values—covalent (disulfide bonds) and non‐covalent bonds (especially hydrophobic interactions and hydrogen bonds)—the intensity of each type of interaction (predicted from solubility tests in buffers with different chemical action) depended on the pH of the initial solution. Films obtained at pH 8 presented the highest solubility in all the buffers, whereas films at formed pH 2 presented the lowest, except in the buffer of pH 8 that contained urea, SDS and 2‐mercaptoethanol, which totally dissolved 100% of the film proteins. Films prepared at extreme pH values had a denser microstructure than those at pH 8. SDS–PAGE patterns indicated that films were mainly formed by β‐conglycinin and glycinin, which aggregated in different forms during film formation, depending on the pH of the initial solutions. Some of these proteins remained weakly bonded and/or were held by the network of films. These differences in the protein networks structure would affect the physical, mechanical and barrier properties of the films. Copyright © 2006 Society of Chemical Industry     

The impact of anthocyanin-rich red raspberry extract (ARRE) on the properties of edible soy protein isolate (SPI) films

To modify the properties of edible soy protein isolate (SPI) films, 0.5% anthocyanin-rich red raspberry (Rubus strigosus) extract (ARRE) (0.5 g raspberry powder in 95% ethyl alcohol/water/85% lactic acid [80:19:1. v/v/v]) was incorporated into film-forming solutions. ARRE resulted in an SPI film having significantly enhanced tensile strength (P < 0.05) and % elongation at break (P < 0.05), as well as increased water swelling ratio (P < 0.05) and in vitro pepsin digestibility (P < 0.05). The resultant films also showed significantly decreased water solubility and water vapor permeability (P < 0.05). In addition, ARRE increased darkness, redness, and yellowness film appearance as evidenced by a lower L* (P < 0.05), greater positive a* (P < 0.05), and a higher b* (P < 0.05) than the control film. Scanning electron microscopy images revealed that extract-added films had denser and more compact cross-section microstructure. Fourier transform infrared spectra illustrated that ARRE-created hydrogen bonding involved conformational changes of soy protein without destroying its backbone structure. SDS-PAGE electrophoretograms revealed that the extract induced intermolecular interaction of the soy protein monomers. Natural plant extracts would be a promising ingredient to make SPI films with different physicochemical properties and applications. PRACTICAL APPLICATION: This study characterizes the potential physicochemical changes of SPI film with incorporated raspberry extract. Upon the above modification, the resultant film was found to enhance the applications of pure SPI film in food packaging. For example, SPI-ARRE film could prolong the usage life of SPI film due to increased strength, or could be useful as a desiccant (drying agent) such as a water-absorbing sheet for preserving dried foods due to its increased hydrophilic surface and water-swelling ratio. SPI-ARRE film could also be alternately used as a food wrap with unique color.     

Edible films made from membrane processed soy protein concentrates

Edible films were prepared from membrane processed soy protein concentrate (MSC) at various film forming solution pHs, and their mechanical, barrier, and physical properties were compared with soy protein isolate (SPI) films. As the film solution pH increased from 7 to 10, the resulted MSC films were more transparent, yellowish, and had lower oxygen permeabilities. However, tensile strength (TS), modulus of elasticity (ME) and water vapor permeabilities of MSC films were not affected by film solution pHs. The values of MSC films prepared at pH 7 were not significantly (P>0.05) different from those of SPI films prepared at alkaline solutions (pH 8-10). The uniform TS and ME values of MSC film over the wide film solution pH ranges were attributed to the higher solubility of MSC at pH 7. For the films formed at neutral film solutions (pH 7.0), MSC films showed significantly (P<0.05) higher elongation value, film solubility, and transparency compared to SPI films.     

增塑剂对大豆蛋白可食膜特性的影响

研究了增塑剂对大豆分离蛋白膜(热法成膜和酶法成膜)成膜特性的影响。增塑剂的种类(甘油、山梨醇或甘油山梨醇的等量混合物)对大豆分离蛋白膜的性能有明显影响。无论是否添加谷氨酰胺转移酶(TGase)，以山梨醇为增塑剂的膜都具有最高的抗拉强度、表面疏水性和总可溶性物量，最低的断裂伸长率、水分含量和透光率。TGase处理SPI(4U／g．蛋白)，可显著改善蛋白膜的抗拉强度和表面疏水性，抗拉强度和表面疏水性分别比对照膜增加10％～20％和17％～56％(P≤0.05)；同时也明显降低了(P≤0.05)膜的断裂伸长率、水分含量、总可溶性物量及透光率。     

Protein and glycerol contents affect physico-chemical properties of soy protein isolate-based edible films

This study was conducted to determine the effect of both soy protein and glycerol contents on physico-chemical properties of soy protein isolate-based edible (SPI) films. The aim of this study was to better understand the influence of SPI and GLY contents on the behavior of the physico-chemical properties of soy protein isolate-based films. Films were casted from heated (70 °C for 20 min) alkaline (pH 10) aqueous solutions of SPI at 6, 7, 8, and 9 (w/w %), glycerol (50%, w/w, of SPI) and SPI at 7 (w/w %), glycerol (40, 60, 70 %, w/w of SPI). Water vapor permeability (WVP), was measured at 25 °C and for four different relative humidities (30–100%, 30–84%, 30–75%, 30–53%). Surface properties and differential scanning calorimetry were also measured. Varying the proportion of SPI and GLY had an effect on water vapor permeability, wetting and thermal properties of SPI films. A synergistic effect of glycerol and protein was observed on the water vapor permeability. Glycerol and RH gradient strongly enhance the moisture absorption rates and permeability of SPI based films. SPI content weakly increases the WVP and does not modify the surface properties. The temperature of denaturation of soy protein decreases glycerol content except for the higher concentration whereas it increases with protein ratio.Industrial relevanceThis topic of research aims to control mass transfers within composite foods or betweenfoods and surrounding media (for instance the headspace in packagings). The targeted applications from this work deals with the food product coating or the coating of paper-based packaging for limiting both the loss of water and flavors by cheese based products. This will allow to maintain the weight of the cheese during “ripening” and commercialization, and also to prevent (off-) flavour dissemination from very odorant cheese as produced in France and Poland.     

Structure-modifying alkaline and acidic pH-shifting processes promote film formation of soy proteins

The effect of pH-shifting, a process that induces the molten globule state in proteins, on the film-forming potential of soy protein isolate (SPI) at different temperatures was investigated. Partial unfolding at pH 1.5 or 12, followed by refolding at pH 7.0, was performed to alter the protein structure. Glycerin-plasticised films were prepared from pH-treated SPI at ambient temperature (20 °C), or by heating at 50, 60, 70, or 80 °C (30 min). Tensile strength (TS), elongation at break (EAB), water vapour permeability (WVP), protein solubility (pH 3–7), and non-participating proteins of films were analysed, and the film microstructures were examined. The pH₁₂-treated SPI spontaneously formed a transparent, slightly yellowish film at 20 °C, which had the greatest EAB, while pH_1.5-treated and native SPIs required preheating at 50 and 70 °C, respectively, to form a film. Heating generally decreased solubility and WVP but increased TS. Films formed from both pH₁₂- and pH_1.5-treated SPIs were more elastic (up to 2-fold greater in EAB, P < 0.05) than the film formed from untreated SPI despite slightly reduced TS and WVP. Electrophoresis revealed disulphide bonds between A and B subunits of glycinin being a dominant force in pH₁₂- and pH_1.5-treated SPI films, while noncovalent forces were abundant in untreated SPI films. The pH₁₂-treated SPI film consisted of more interactive protein strands than other SPI films, which seemed to explain its superior elastic properties.     

Structural and functional properties of soy protein isolate and cod gelatin blend films

The structure-function relationship of composite films obtained from soybean-protein isolate (SPI) and cod gelatin was studied. Films with different ratios of SPI:gelatin (0, 25, 50, 75, 100% [w/w]) and plasticized by a mixture of glycerol and sorbitol were prepared by casting. Regardless of the soybean-protein concentration, the thickness and water-vapor permeability of the composite films diminished significantly as compared to pure-gelatin films. The formulation containing 25% SPI: 75% cod-skin gelatin had the maximum force at the breaking point, which was 1.8-fold and 2.8-fold greater than those of 100% gelatin and 100% SPI films, respectively. Moreover, this formulation offered high percent-deformation values lower than those of gelatin but higher than all other films containing SPI-, and the same relatively low water-vapor permeability as the 100% SPI film. While all the films exhibited high water solubility, a slight reduction in film solubility and soluble protein was observed with increasing SPI concentration. Differential-scanning calorimetry analyses revealed that gelatin was completely denatured in all films, while soy proteins largely maintained their native conformation. Analysis by fourier-transform–infrared spectroscopy revealed that the presence of 25% SPI produced gelatin conformational changes, self-aggregation of gelatin chains, and intermolecular associations via CO bonds between gelatin and SPI proteins. All films were translucent in appearance, but the yellowish color increased with increasing proportions of the soybean proteins.     

Sorption Characteristics of Soy Protein Films and their Relation to Mechanical Properties

Effects of plasticizers (glycerol, sorbitol, and 1:1 mixture of glycerol and sorbitol) on moisture sorption characteristics of hydrophilic soy protein isolate (SPI) films were investigated at three levels of plasticizer concentration (0.3, 0.5, and 0.7 g plasticizer/g SPI). The combined effects of relative humidity and plasticizer on mechanical properties of soy protein films were also examined. Moisture affinities of soy protein films were affected by hydrophilicity of plasticizer and its concentration. Under given RH conditions, films with higher glycerol ratio absorbed more moisture with higher initial adsorption rate, and films with higher plasticizer contents exhibited higher equilibrium moisture contents. Monolayer moisture contents of SPI films increased as glycerol ratio in a plasticizer mixture and plasticizer concentration increased. Plasticizer and absorbed water loosened the film synergistically, resulting in higher elongation but lower tensile strength. RH effects on mechanical properties of SPI films were varied with plasticizers and their concentration. Films of lower glycerol contents were more sensitive to RH variation as compared to the higher glycerol samples, whereas sorbitol concentration affected the RH region where a sharp decrease in TS value occurred.     

冷冻保藏对大豆分离蛋白膜机械性能的影响

用大豆分离蛋白(SPI)制备可食性包装膜时,在成膜溶液中分别添加单甘酯、葡萄糖制成大豆分离蛋白膜,将其分别在室温下(RH65%)保存2d以上和在冷冻保藏7d后测定机械性能,发现添加这些物质后制得的膜的机械性能均受到影响:含单甘酯的膜的抗拉强度(TS)增加超过25%,断裂伸长率(E)变化不大;而含葡萄糖的膜TS增加了35%以上,E增加了55%以上。冷冻对各种SPI膜的机械性能有不同影响,对含葡萄糖的SPI膜的抗拉强度影响很大,TS下降达50%,对其他SPI膜的影响不太大,这意味着不含葡萄糖的SPI膜可用于冷冻食品包装。     

Properties of cast films of vicilin-rich protein isolates from Phaseolus legumes: Influence of heat curing

The mechanical, hydrophobic and thermal properties of cast films of vicilin-rich protein isolates from three Phaseolus legumes were investigated and compared to that of soy protein isolate (SPI). The influence of heat curing at 85 °C on the properties of these films was characterized. The films of vicilin-rich protein isolates exhibited much less mechanical strength (TS) and elongation at break (EB) and similar film surface hydrophobicity, as compared with those of the SPI film. The heating remarkably improved the TS of these films, and the extent of the improvement much higher than that of the SPI film, while the EB was only slightly affected. The thermal properties of these protein isolate films were variable, and much distinctly affected by the heating of the films, to a various extent, depending on the type of protein isolates. Protein solubility analyses indicated strengthened hydrogen and hydrophobic bondings of these films by the heating. The results suggest that those vicilin-rich protein isolates have good potential to form cast films with mechanical strength comparable to that of SPI film.