Comparison of the properties of gels derived from cod surimi and from unwashed and once-washed cod mince

Surimi is a washed and stabilized fish mince with valuable gel-forming properties. However the preparation process is wasteful and a modified process, with less washing, was investigated. The properties of the gels (cooked at 40°C for 30 min followed by 90°C for 40 min) were assessed by instrumental and sensory methods. Gels prepared from surimi were soft and very flexible; gels from unwashed fresh cod mince were firmer and less elastic, but still gave a maximum score on the folding test. A single wash made the gels firmer and slightly more elastic than those from unwashed mince. Gels from unwashed mince of frozen cod were firmer than surimi-derived gels, and were the most brittle. Sensory assessment of the gels found no difference in firmness between the different washing procedures and small differences in elasticity and toughness. The addition of starch (fish: starch, 100:5, w/w) increased the firmness and sensory toughness of each derived gel, and reduced the elasticity in the mouth of non-surimi gels. The colour of gels derived directly from fish was off-white, compared with the white surimi-derived gels. The colour of the former darkened during frozen storage, but lightened again after thawing.     

食盐和大豆蛋白对牛肉凝胶特性的影响

主要研究了食盐和大豆蛋白对牛肉凝胶特性及颜色的影响,结果表明:随食盐添加量的增加,牛肉糜的凝胶硬度、弹性和粘聚性均增加,亮度L值显著降低,对红色度a值影响不显著;随大豆分离蛋白添加量的增加,凝胶硬度逐渐增加,弹性逐渐降低,对粘聚性的影响不显著,并使牛肉糜的亮度L值显著降低,但对红色度a值影响不显著。     

鱼糜凝胶形成机理及提高鱼糜凝胶特性的添加物研究新进展

鱼糜凝胶特性是评价鱼糜品质的重要指标,介绍了鱼糜凝胶形成机理及引起凝胶劣变的内在因素,综述了目前用于提高鱼糜凝胶特性的添加剂最新研究进展,为我国淡水鱼鱼糜加工发展提供理论依据。     

淘汰蛋鸡肉糜功能特性影响因素研究进展

淘汰蛋鸡肉糜加工过程中的漂洗，加热，添加剂应用是影响其功能特性的主要因素。作者介绍了淘汰蛋鸡肉糜的功能特性，并对其主要影响因素－加工工艺和添加剂进行了综述论述。     

Effects of konjac glucomannan on physicochemical properties of myofibrillar protein and surimi gels from grass carp (Ctenopharyngodon idella)

The cryoprotective effect of konjac glucomannan (KGM) on myofibrillar protein from grass carp (Ctenopharyngodon idella) during frozen storage at −18 °C and the influence of five levels of KGM (0%, 0.5%, 1%, 1.5%, and 2%) on texture properties, water-holding capacity, and whiteness of grass carp surimi gels were investigated. KGM as a novel cryoprotectant could significantly mitigate the decrease in salt extractable protein (SEP), Ca²⁺-ATPase activity, and total sulphydryl and active sulphydryl contents of myofibrillar protein during frozen storage. KGM at the level of 1% showed the same good cryoprotective effect as a conventional cryoprotectant (10% sucrose–sorbitol, 1:1, w/w). As the levels of KGM increased, breaking force and deformation of grass carp surimi gels increased significantly. Water-holding properties of the surimi gels are improved with the increasing addition of KGM, but the whiteness decreased and the colour became darker. The optimum addition level of KGM was suggested to be 1%.     

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.     

Effect of freeze–thaw cycles and additives on rheological and sensory properties of ready to bake frozen chapaties

The wheat grains were conditioned at 18% moisture level for 1 h followed by heating for 80 s in a microwave oven to reduce the activity of polyphenol oxidase as well as other lipolytic and oxidative enzymes. The dough samples were prepared from whole wheat flour (milled from microwave treated wheat grains) using 68% water and 2% salt on flour weight basis as common ingredients. The additives like glycerol monostearate and glycerol (5% and 1% respectively on flour weight basis) were also used in order to study their effects on the quality of ready to bake frozen chapaties (R-BFC) during freeze–thaw cycles. Alveographic properties of R-BFC as well as textural profile and sensory quality of chapaties prepared from R-BFC samples were evaluated during repeated freeze–thaw (FT) cycles. Results showed that the alveographic properties (P, L, and W) decreased significantly ( P  ≤   0.05) in all the samples after each FT cycle, while glycerol added samples showed the least changes. Chapati hardness increased in all the samples up to fourth FT cycle, thereafter sharply decreased. However, chapaties with 1% glycerol were rated better in terms of mouth feel and texture during FT cycles.     

四种非肌肉蛋白对冷冻竹荚鱼鱼糜凝胶能力的影响研究

探讨了四种常用的非肌肉蛋白对竹荚鱼鱼糜凝胶特性的影响,对不同鱼糜加热过程中凝胶强度、持水力、白度、SDS-PAGE电泳图谱以及微观结构的变化进行比较。实验结果表明,血浆蛋白对冷冻竹荚鱼的蛋白酶有很强的抑制效果,最佳添加量为1%。卵清蛋白及乳清蛋白在5%高浓度时其凝胶增强效果与1%的血浆蛋白添加效果近似,大豆蛋白的效果较差,四种蛋白对鱼糜白度、持水力影响不大。非肌肉蛋白应用于竹荚鱼鱼糜的品质改善中,对凝胶劣化有一定的抑制,这对竹荚鱼鱼糜的品质控制具有一定意义。     

食品添加剂对牛初乳免疫球蛋白(IgG)稳定性的影响

探讨了几种常用食品添加剂对牛初乳免疫球蛋白稳定性的影响,根据食品添加剂对IgG的变性率的影响,选择了几种在食品加工中常用的添加剂进行正交试验,考察其相互综合作用。结果表明:随着柠檬酸、乳酸和磷酸二氢钠浓度的增大,免疫球蛋白的稳定性逐渐降低,变性率逐渐增大;山梨酸钾对免疫球蛋白的稳定性影响较小;磷酸氢二钠、乳酸钙、增稠剂和甜味剂对免疫球蛋白有一定的保护作用。添加剂最佳用量为:乳酸用量为0.3%,乳酸钙用量为0.015%,黄原胶用量为0.5%,蔗糖用量为8%,此时IgG的变性率为14.7%,在4℃的贮藏条件下最佳保存期为30天。     

添加剂对冷冻水饺品质的影响

研究了抗坏血酸、亲水性单甘酯、褐藻酸钠三种添加剂对冷冻水饺品质的影响,得出了有效改良冷冻水饺品质的复合添加剂组合:亲水性单甘酯0.5%,抗坏血酸0.006%,褐藻酸钠0.5%(均以面粉添加量计)。     

The effects of chickpea on the functional properties of white and whole wheat bread

The effects of the addition of chickpea (Cicer arietinum), emulsifier and altered amount of water on the functional properties (bread volume, colour of crust, crumb texture and crumb porosity) of white and whole wheat bread were investigated applying a screening three factorial design. Addition of chickpea increased crumb firmness and slightly decreased bread volume in both bread types. Addition of emulsifier increased bread volume and decreased bread firmness. Altering the amount of water addition had no significant effects on white bread, but decreased crumb firmness and increased bread volume in whole wheat bread. None of the investigated parameter had an effect of whole wheat bread colour, while in white bread chickpea addition increased darkness and yellowness of the bread. Optimum addition for breads of highest quality would be 56.9–58% water, 1.0% emulsifier and 10.0–16.0% chickpea in white bread and 58% water, 1.0% emulsifier and 11.8% chickpea in whole wheat bread.     

食品添加剂对大米淀粉流变特性的影响

采用动态流变仪对米线生产中三种常用添加剂焦磷酸钠、单甘酯和淀粉醋酸酯对大米淀粉流变特性的影响进行了研究。研究结果表明：适当添加焦磷酸钠可以通过糊化时抑制淀粉颗粒的崩溃解体来提高大米淀粉凝胶体系的强度；添加单甘酯由于单甘酯与直链淀粉形成了络合物，因而大米淀粉凝胶强度显著降低；淀粉醋酸酯的添加可以适度降低大米淀粉凝胶的强度，提高淀粉凝胶的柔韧性。     

The effect of par‐baking and frozen storage time on the quality of cup cake

The effects of frozen storage and initial baking time of par‐baked cake on baking loss, volume, moisture, colour and textural properties of cake obtained after thawing and rebaking were investigated. Cakes, par‐baked at 175 °C for 15, 20 and 25 min, were stored at ?18 °C for 3, 6 and 9 months. After storage, par‐baked cakes were thawed and rebaked at 175 °C for 10, 15 and 20 min. Baking loss, moisture content, L and +b colour values, firmness, gumminess and chewiness of the resulting full‐baked cakes were significantly affected by both par‐baking and frozen storage time, while specific volume, cohesiveness, springiness and resilience values were significantly affected by frozen storage time. The increase in the time of frozen storage of the par‐baked cake leads to a decrease in the quality of the rebaked cake, namely an increase of baking loss and cake crumb firmness, and a loss in the moisture content and specific volume. Moisture of cake crumb, L and +b colour values, firmness, gumminess and chewiness significantly increased as the par‐baking time increased. However, regarding baking loss, specific volume, moisture content and textural properties, 3‐month intermediate storage at ?18 °C and 20‐min initial baking time gave the best result among the cakes produced by using the two‐step baking procedure.     

低聚木糖对面团热机械特性及冷冻面团发酵流变特性的影响研究

采用Mixolab酶流变分析仪和流变发酵仪研究了低聚木糖对面团热机械特性和对冷冻面团发酵流变特性的影响,结果表明低聚木糖有强化面筋、增加面团耐揉性和耐蒸煮性的作用。引入低聚木糖会使流变发酵仪中的气体释放曲线和面团发展曲线的最大高度以及面团的持气率较空白组有不同程度的提高。     

丙二醛氧化修饰对大豆蛋白热变性影响

以丙二醛代表脂质过氧化活性次生产物,采用圆二色谱、内源荧光光谱、粒径分析和差示扫描量热仪研究丙二醛氧化修饰对大豆蛋白热变性影响。结果发现,丙二醛氧化修饰使大豆蛋白热稳定性下降,相比大豆球蛋白,大豆β-伴球蛋白热稳定性下降更为显著。     

干燥方式对SPC功能性和结构的影响

通过研究不同干燥方法(冷冻干燥和喷雾干燥)对SPC(大豆浓缩蛋白)的NSI(氮溶指数)、起泡性和乳化性的影响,并利用凝胶电泳和傅立叶红外光谱方法研究不同干燥方法对SPC结构的影响;探讨SPC功能性质改善的机理。     

蛋白质的组成对盐溶蛋白热诱导凝胶特性的影响研究

肌肉盐溶蛋白质形成凝胶的特性是肉制品加工中最重要的功能特性之一,以对虾肉为试材,分别以对虾肉盐溶蛋白热诱导凝胶的硬度、弹性以及黏性为依据,通过聚丙烯酰胺凝胶电泳图谱的比较,得出不同蛋白质的组成对热诱导凝胶特性产生较大的影响,主要的蛋白带出现在31～212ku之间;其组成为肌球蛋白、肌动蛋白、肌原纤维蛋白碎片;电泳图谱中肌球蛋白带宽且颜色深的,其热诱导凝胶的加工特性就越好。     

环境温度对植物蛋白膜的影响

研究了环境温度对小麦蛋白膜、大豆蛋白膜以及小麦-大豆复合膜机械性能,通透性等的影响。结果表明,由于蛋白膜易受环境温度的影响,从而导致蛋白膜的机械性能,透湿性和透氧率等也随之发生变化。环境温度对复合膜的抗拉强度影响不大,而延伸率均随着环境温度的上升而增高。其透氧率随着环境温度的升高而上升,水蒸汽透过率随着环境温度的升高先略有下降,而后又呈上升趋势。