Effects of nonprotein substances on protein hydrolysis and plastein formation

Effects of various naturally occurring nonprotein substances (carbohydrates, polysaccharides, fats and salts) on enzymatic hydrolysis of soy protein isolate and plastein formation from hydrolyzed soy protein were investigated. Relative extent of hydrolysis and plastein formation were measured as protein solubility in 10% trichloroacetic acid (TCA) since this method was found suitable for analysis of turbid, viscous and/or low protein samples. The presence of guar, xanthan, locust bean and arabic gums, arabinogalactan, unsaturated fatty acids (2%), salt mixture and xylan were found to enhance soy protein peptic hydrolysis at 0·5% enzyme/substrate; unsaturated fatty acids (1%) inhibited hydrolysis. At enzyme/substrate of 3·5%, hydrolysis was enhanced by xanthan gum, unsaturated fatty acids and sodium chloride but inhibited by gum karaya, salt mixture, starch, cellulose, and saturated fatty acids. Plastein synthesis was inhibited by xanthan, locust bean and guar gums but stimulated by arabinogalactan. Several nonprotein substances were found to interfere with the TCA solubility assay. Positive interference was noted for systems containing saturated and unsaturated fatty acids and magnesium, but negative interference was observed for systems containing guar gum, xanthan gum, calcium chloride and gum arabic.     

Controlling rheology and structure of sweet potato starch noodles with high broccoli powder content by hydrocolloids

Incorporating high volume fractions of broccoli powder in starch noodle dough has a major effect on its shear modulus, as a result of significant swelling of the broccoli particles. Several hydrocolloids with distinct water binding capacity (locust bean gum (LBG), guar gum, konjac glucomannan (KG), hydroxypropyl methylcellulose (HPMC) and xanthan gum), were added to systems with 4 and 20% (v/v dry based) broccoli particles, and the effect of this addition on dough rheology, mechanical properties and structure of cooked noodles was investigated. Hydrocolloids with low (LBG and guar gum) and intermediate (KG) water binding capacity had no significant effect on shear rheology of the dough. Adding hydrocolloids with high water binding capacity (HPMC and xanthan gum) decreased the shear modulus of dough with 20% broccoli particles significantly. CLSM analysis of cooked noodles showed that in samples containing xanthan gum there was also an inhibition of swelling of starch granules. Strength and stiffness of cooked noodles with 20% broccoli particles were higher for samples containing xanthan gum, than samples without xanthan gum. The cooking loss and swelling index of samples with added hydrocolloids were slightly lower than samples without hydrocolloids. Our results showed that hydrocolloids with high water binding capacity can be used to control the degree of swelling of vegetable particles and starch granules in starch noodle products, and thereby control both dough rheology and textural properties of the cooked noodles.     

亲水胶体对鸡蛋清起泡性的影响

亲水胶体在许多食品的制作过程中都起到重要的提升产品品质的作用。研究分析了黄原胶、海藻酸钠、羧甲基纤维素(CMC)、瓜尔豆胶和壳聚糖等几种亲水胶体的不同添加量对鸡蛋清的打擦度、起泡性及泡沫稳定性的影响。结果表明亲水胶体添加CMC、瓜尔豆胶可明显增加蛋清的打擦度,添加海藻酸钠则降低蛋清的打擦度,而黄原胶的添加对蛋清打擦度的影响则受到不同的添加量分别出现打擦度增加和降低的不同结果,壳聚糖的添加对蛋清的打擦度影响不大。研究过程也发现,蛋清中添加黄原胶、CMC、瓜尔豆胶和壳聚糖后,泡沫达到最大体积的时间比对照组明显缩短,蛋清起泡效率提高。几种胶体的添加增加蛋清打擦度由大到小顺序为:瓜尔胶>CMC>壳聚糖≈对照(无添加)>黄原胶>海藻酸钠。添加亲水胶体可以增强鸡蛋清的泡沫稳定性。     

Heat stability of oil-in-water emulsions formed with intact or hydrolysed whey proteins: influence of polysaccharides

The heat stability of emulsions (4 wt% corn oil) formed with whey protein isolate (WPI) or extensively hydrolysed whey protein (WPH) products and containing xanthan gum or guar gum was examined after a retort treatment at 121 °C for 16 min. At neutral pH and low ionic strength, emulsions stabilized with both 0.5 and 4 wt% WPI (intact whey protein) were stable against retorting. The amount of β-lactoglobulin (β-lg) at the droplet surface increased during retorting, especially in the emulsion containing 4 wt% protein, whereas the amount of adsorbed α-lactalbumin (α-la) decreased markedly. Addition of xanthan gum or guar gum caused depletion flocculation of the emulsion droplets, but this flocculation did not lead to their aggregation during heating. In contrast, the droplet size of emulsions formed with WPH increased during heat treatment, indicating that coalescence had occurred. The coalescence during heating was enhanced considerably with increasing concentration of polysaccharide in the emulsions, up to 0.12% and 0.2% for xanthan gum and guar gum, respectively; whey peptides in the WPH emulsions formed weaker and looser, mobile interfacial structures than those formed with intact whey proteins. Consequently, the lack of electrostatic and steric repulsion resulted in the coalescence of flocculated droplets during retort treatment. At higher levels of xanthan gum or guar gum addition, the extent of coalescence decreased gradually, apparently because of the high viscosity of the aqueous phase.     

响应面法优化复合植物蛋白饮品的稳定体系

用响应面方法对复合植物蛋白饮品的稳定体系进行了优化。先用全因子实验对稳定剂组分卡拉胶、瓜尔豆胶、黄原胶和结冷胶对复合植物蛋白饮品沉淀量的影响进行了评价,并找出主要影响因子为瓜尔豆胶和结冷胶,其它组分对沉淀量没有显著影响。采用中心组合设计及响应面分析确定主要影响因子的最佳浓度。稳定体系的最佳组成为(g/L):卡拉胶0.2、瓜尔豆胶0.5、黄原胶0.2、结冷胶0.5,此条件下复合植物蛋白饮品表现出良好的稳定性。     

盐及非盐物质对常用低浓度食品胶溶液粘度影响的研究

对饮料生产中常用的食品胶－黄原胶、海藻酸钠、瓜尔胶和琼脂在低浓度水相体系中外加盐（阴、阳离子）、乙醇、蔗糖及柠檬酸对溶液粘度的影响作了探讨性研究,结果表明四种胶溶液（０．１０％黄原胶、０．３０％海藻酸钠、０．２５％瓜尔胶、０．１０％琼脂）中、瓜尔胶溶液对盐的耐受性最好,即大多数阴阳离子都不会对其粘度产生影响,而常用金属盐阳离子及Ｃｌ＾－、ＳＯ３＾２－对黄原胶溶液粘度的影响与阴阳离子对海藻酸钠和琼脂     

四种添加剂的流变性能研究

论文主要对四种添加剂进行了流变性能的研究,四种添加剂中,黄原胶、瓜尔豆胶其胶体溶液流变性有更多的相似性,它们浓度在0.3%以上时,均为非牛顿型流体,CMC浓度在0.5%以上时为非牛顿型流体,且为非触变性流体.海藻酸钠胶体溶液为牛顿型流体.四种添加剂胶体溶液的粘度,瓜尔豆胶＞黄原胶＞CMC＞海藻酸钠.但在搅动环境下,当剪切力大于一定的屈服应力时,剪切稀化效应将导致粘度的下降,下降幅度为瓜尔豆胶＞黄原胶＞CMC.黄原胶更具有独特的流变性、优良的热稳定性、酸稳定性,其次为瓜尔豆胶.CMC、海藻酸钠的热稳定性并不是很好,在高酸性的环境条件下,海藻酸钠的粘度反而增加.     

Optimization of low-cholesterol–low-fat mayonnaise formulation: Effect of using soy milk and some stabilizer by a mixture design approach

In the present study, the optimized mixture proportions of low cholesterol-low fat mayonnaise contained soy milk as an egg yolk substitute (10%) with different composition of xanthan gum (XG), guar gum (GG) and mono- & diglycerides emulsifier (MDG) (0–0.36% of each component) were determined by applying the simplex-centroid mixture design method to achieve the desired stability, textural and rheological properties and sensory characteristics for effective formulation process. Results revealed that the best mixture was the formulation contained 6.7% mono- & diglycerides, 36.7% guar gum and 56.7% xanthan gum. The xanthan gum was the component showing the highest effect on all the properties of mayonnaise samples. In addition, an increase of xanthan gum followed by guar gum caused greater values for the stability, heat stability, consistency coefficient, viscosity, firmness, adhesiveness, adhesive force and overall acceptance and lower value for flow behavior index. Depending on the desirable level of xanthan gum, guar gum and mono- & diglycerides, creation of low cholesterol-low fat mayonnaise with properties closely matching those of commercial ones is possible.     

EFFECT OF LIPASE ENZYME ON THE RIPENING OF WHITE PICKLED CHEESE

The effect of addition of pregastric lipase enzyme on the accelerated ripening of white pickled cheese was investigated. Commercial pregastric lipase was added to milk before rennet addition at a level of 0,5, 8, 11 g per 100 L of milk and cheeses were made from this milk. Total solids, fat, total nitrogen, salt, titratable acidity, pH and free fatty acids (C₂-C_18:1) were analysed in the samples during 1–90 days of ripening period at 15 days intervals. Total solids, fat, total nitrogen, salt, titratable acidity, and pH of cheeses slightly increased during the ripening period. Free fatty acids and volatile free fatty acid contents in cheeses made from pregastric lipase added milk were affected by pregastric lipase and their contents were increased significantly (P<0.01) during the ripening period. Particularly, when cheese had a high level (11 g per 100 L milk) pregastric lipase, the amounts of butyric, caproic and caprylic acids in white pickled cheese were quite high. The relative amounts of volatile free fatty acids varied with storage time and pregastric lipase levels.     

不同单一胶体对花生乳稳定性的影响

研究了黄原胶、瓜尔豆胶、CMC-Na在单因素条件下对花生乳稳定性的影响,通过花生乳室温下放置24h后静置观察、分析样品的黏度、离心沉淀率和脂肪上浮率。结果表明:3种胶体对花生乳体系均有一定的增黏作用,适宜的质量分数均能提高体系的稳定性,其中黄原胶、瓜尔豆胶、CMC-Na的适宜用量分别为≤0.02%、0.01%-0.03%、0.02%-0.04%。     

增稠剂对冷冻面团品质影响的研究

以高筋粉及特一粉冷冻面团为对象,研究添加黄原胶、瓜尔豆胶、卡拉胶、聚丙烯酸钠增稠剂对冷冻面团拉伸特性、湿面筋含量、失水率及色泽的影响。结果表明：对于特一粉,黄原胶（0.3%）、瓜尔豆胶（0.8%）、卡拉胶（0.6%）、聚丙烯酸钠（0.05%）添加时,拉伸面积和湿面筋含量最高;对于高筋粉,黄原胶（0.2%）、瓜尔豆胶（1.2%）、卡拉胶（0.6%）、聚丙烯酸钠（0.05%）添加时,拉伸面积和湿面筋含量最高;冷冻面团加入增稠剂后,失水率有所减小,但规律性不强;随着黄原胶、瓜尔豆胶、聚丙烯酸钠添加量的增加,L值增大,面团亮度增强,但随着卡拉胶添加量的增加L值减小,面团亮度减弱。     

食品增稠剂瓜儿豆胶性质及复配性的研究

本文对瓜尔豆胶的流变性,浓度、温度、pH值、电介质对粘度的影响,与黄原胶、卡拉胶复后粘度变化进行了初步研究。结果表明,低浓度瓜儿豆胶属非牛顿流体中假塑性流体,其粘度随浓度升高而上升,随温度升高而下降,几乎不受pH值影响,对NaCl和低浓度Ca~(2+),Al~(3+)有良好兼容性,与卡拉胶复配无增效作用,而与黄原胶复配增效显著,复配最佳比例为瓜儿豆胶:黄原胶=0.6:0.4     

Viscosity of guar gum and xanthan/guar gum mixture solutions

The viscosity of diluted guar gum solutions and the viscosity of xanthan and guar gum mixture solutions have been studied. Guar gum solutions showed pseudoplastic behaviour. Apparent viscosity increased with gum concentration and decreased with the temperature at which viscosity was measured. A maximum in the plot of viscosity versus increasing dissolution temperature was observed at 60 °C. This behaviour was related to differences in molecular structure of the polymers solved at different temperatures. Mixtures of xanthan and guar gum showed a higher combined viscosity than that occurring in each separate gum. This synergistic interaction was affected by the gum ratio in the mixture and dissolution temperature of both gums. The effect of polysaccharide concentration (1.0, 1.5 and 2.0 kg m⁻³), xanthan/guar gum ratio (1/5, 4/2, 3/3, 4/2 and 5/1) and dissolution temperature (25, 40, 60 and 80 °C for both gums) on the viscosity of solutions of mixtures were studied. The highest viscosities were observed when 2.0 kg m⁻³ gum concentration was used together with a ratio of xanthan/guar gum of 3/3 (w/w) and dissolution temperature of 40 and 80 °C for xanthan and guar gum, respectively. © 2000 Society of Chemical Industry     

四种常见亲水胶体对面团特性的影响研究

采用粉质仪、快速黏度分析仪和流变仪研究添加黄原胶、κ-卡拉胶、魔芋胶和瓜儿豆胶对小麦粉粉质特性、糊化特性及面团流变特性的影响.研究结果表明,亲水胶体可以提高小麦粉的黏度,改善面团的黏弹特性,不同亲水胶体的作用效果存在差异,添加质量分数1%的黄原胶和魔芋胶后小麦粉吸水率分别增大了4.9%和7.9%,添加质量分数1%黄原胶、κ-卡拉胶和瓜儿豆胶后小麦粉糊的糊化温度分别降低了21.35℃、18℃、14.7 ℃,添加黄原胶和瓜儿豆胶能够显著地提高面团的稳定性,而添加魔芋胶能够延缓淀粉的重结晶特性.     

Effect of Anionic Gums on the Texture of Pickled Frankfurters

The addition of the anionic gums, xanthan and carrageenan, stabilized the texture of frankfurter emulsions against acid deterioration at 37°C in vinegar pickle. The proteins collagen, casein, and gluten, and the gums guar, arabic, and locust bean had no effect. The cationic gum, chitosan, formed an acid-stable gel but the gel would not hold the emulsion. The process of acid deterioration had an initial period of firming of the gel texture. Shear (rupture) and elasticity did not show a corresponding initial increase. Subsequent deteriorative changes were less in the emulsions with xanthan gum than in any of the other emulsions. The gum gel is formed at the expense of the protein-fat structure, probably through a gum-protein interaction.     

榛子乳饮料加工工艺及其稳定性研究

研究以棒子为主要原料的植物蛋白饮料的加工工艺及其稳定性.着重对CMC、卡拉胶、黄原胶等单一稳定剂,单甘脂、蔗糖脂、吐温80等乳化剂及乳化稳定剂在棒子乳饮料中的稳定效果进行研究.试验表明,在棒子乳饮料中0.08%卡拉胶、0.08%瓜尔豆胶、0.1%蔗糖脂,0.15%复合稳定剂效果最佳;70℃、35 MPa的条件均质有较好的效果;采用121℃、20 min的高温高压杀菌.     

Conformational Role of Xanthan Gum in its Interaction with Guar Gum

ABSTRACT: :
Ubbelohde viscometry, texture analysis, and centrifugation were used to investigate the effects of chain conformational changes of xanthan or deacetylated xanthan gum on its interaction with guar gum. Guar gum was not effective in denaturing xanthan gum when the xanthan helical structure was stabilized by salt. The intrinsic viscosities of deacetylated xanthan and guar blends were higher than those calculated from the weight averages of the 2. Conformational change was not observed for deacetylated xanthan, presuming deacetylated xanthan was in the exact conformation for guar to bind so that the most stable heterotypic structure between deacetylated xanthan and guar was formed directly, thus the strongest interaction was observed between deacetylated xanthan and guar.     

Influence of non-starch polysaccharides on the in vitro digestibility and viscosity of starch suspensions

The effects of adding non-starch polysaccharides (xanthan gum, guar gum, konjac glucomannan, and pectin) on the starch digestibility and viscosity of raw starch suspensions in a mixed system were determined. Each type of polysaccharide was added to high-amylose corn starch suspensions at defined concentrations. High-amylose rice starch suspensions mixed with xanthan and guar gum were prepared for comparison. The extent of starch digestibility was determined by an in vitro method, and the glucose diffusibility from the dialysis tube in the presence of polysaccharides was measured. The added polysaccharides were observed to decrease the starch digestibility in a mixed system. When compared at the same concentration, xanthan gum showed the most pronounced suppressive effect on starch digestibility and glucose diffusibility from the dialysis tube. The addition of polysaccharides increased the viscosity of the starch suspension. Significant relations were found between the extent of starch digestibility and the apparent viscosity at low shear rate.     

Influence of deacetylation on the rheological properties of xanthan-guar interactions in dilute aqueous solutions

ABSTRACT:  An oscillating capillary rheometer was used to investigate the effects of xanthan deacetylation on the viscoelastic properties and intrinsic viscosity of xanthan and guar mixtures in dilute aqueous solutions. Deacetylated xanthan exhibited a stronger synergistic interaction with guar than native xanthan did due to the destabilized helical structure and increased chain flexibility of the deacetylated xanthan. No gels were observed for all xanthan–guar mixtures. Native xanthan–guar mixtures exhibited a liquid-like behavior, whereas deacetylated xanthan–guar mixtures exhibited a gel-like behavior. The relative viscosity and elasticity of deacetylated xanthan–guar mixtures were much stronger than those for native xanthan–guar mixtures. The intrinsic viscosities of deacetylated xanthan–guar mixtures were higher than the calculated values assuming no interaction, whereas the intrinsic viscosities of native xanthan–guar mixtures were lower than the calculated values assuming no interaction, demonstrating that intermolecular binding occurred between the disordered segments of xanthan and guar gum in dilute aqueous solutions.     

Effects of different types and concentrations of thickeners on yoghurt protein bioaccessibility by an in vitro dynamic gastrointestinal digestive model

This study analysed the protein bioaccessibility of yoghurt containing different concentrations of pectin, acid-resistant carboxymethylcellulose (CMC), guar gum and xanthan gum before and during in vitro gastrointestinal digestion, respectively. Soluble protein contents and protein digestion rates of yoghurt with 0.2% (m/v) guar gum, CMC and xanthan gum were significantly higher and faster, whereas other thickeners had slower rates than control yoghurt during gastric digestion phase. In addition, the contents of small peptides and amino acids were higher in yoghurt with 0.2% (m/v) thickeners than those with 1.0% (m/v) thickeners during simulated intestinal digestion in most of the samples.