提高搅拌型草莓酱、黄瓜汁复合酸奶稳定性研究

通过控制草莓酱、黄瓜汁的添加量,经过二次均质,控制搅拌条件,添加搅拌型酸奶复合稳定剂,控制冷藏条件等措施,提高了搅拌型草莓酱、黄瓜汁复合酸奶的稳定性。     

4种常用稳定剂和丝素蛋白对搅拌型酸奶黏度和保水性的影响

为改善丝素酸奶的品质,采用二因素三水平析因试验设计,考察4种常用稳定剂(果胶、黄原胶、海藻酸钠、耐酸性羧甲基纤维素钠(CMC))与丝素蛋白对搅拌型酸奶黏度、保水性的影响。结果显示:果胶、黄原胶、海藻酸钠和丝素蛋白对搅拌型酸奶的黏度均有极显著的影响(P<0.01),上述3种稳定剂和丝素蛋白对酸奶的黏度均有极显著的交互作用(P<0.01);果胶、黄原胶、耐酸性CMC和丝素蛋白对酸奶的保水性均有极显著的影响(P<0.01),其中黄原胶和丝素蛋白对酸奶的保水性有极显著的交互作用(P<0.01)。获得4个优化组合,分别为0.5%丝素蛋白和0.01%果胶,酸奶的黏度和保水性分别为903.8mPa.s、65.5%;1%丝素蛋白和0.03%黄原胶,酸奶的黏度和保水性分别为1196.2mPa.s、68.0%;1%丝素蛋白和0.03%海藻酸钠,酸奶的黏度和保水性分别为1320.6mPa.s、68.3%;0.5%丝素蛋白和0.05%酸性CMC,酸奶的黏度和保水性分别为962.1mPa.s、65.0%。     

复合菌发酵乳生产及其稳定剂的选择

使用罗地亚MY900复合乳酸菌剂和CMC、黄原胶、变性淀粉、复合稳定剂,对搅拌型酸奶进行应用试验.结果表明当MY900菌剂的接种量为40U/1000L、发酵温度为43℃、发酵时间为5.0～6.0h, 搅拌破乳,制得的搅拌型酸奶口感优良,同时表明使用变性淀粉或复合稳定剂在酸奶生产中是合适的增稠剂.     

TG酶与稳定剂复配改善搅拌型酸奶生产特性的研究

研究了谷氨酰胺转胺酶(TG酶)与稳定剂复配使用后对搅拌型酸奶的黏度、乳清析出率和口感等指标的影响,并对二者的复配工艺进行了优化.与未添加TG酶的酸奶相比,添加TG酶使酸奶的黏度增加了38.9％～75.6％,乳清析出率降低了81.4％～92.5％,酸奶的细腻度和爽滑程度也明显提高,6 U/g的TG酶添加量效果最好,酸奶品质改善明显.与单独使用稳定剂相比,复配TG酶后的酸奶黏度增加了56.6％,乳清析出率有效降低,酸奶保存期从7d延长到了15 d;两者优化配比为F-1001稳定剂用量0.2％,TG酶用量为3 U/g.     

后杀菌技术对延长搅拌型酸奶保质期的研究

研究了用后杀菌技术和复配稳定剂延长搅拌型酸奶保质期的工艺。结果表明,将复配稳定剂应用于后杀菌技术中,由L_9(3~4)正交试验确定酸奶后杀菌的优化工艺条件是:温度64℃,时间20s。贮藏试验表明,后杀菌酸奶在常温下保质期为20d,其乳酸菌活菌数、黏度、色泽和风味都与普通酸奶相近。     

搅拌型酸浆果胡萝卜复合酸奶饮料的研制

以酸浆果、胡萝卜和酸奶为主要原料,研制搅拌型酸浆果胡萝卜复合酸奶饮料。方法:以饮料感官品质为考察指标,通过单因素试验、正交试验,确定搅拌型酸浆果胡萝卜复合酸奶饮料的最佳配方。最佳配方为:酸奶中酸浆果汁、胡萝卜汁比7∶3,混合汁添加量为15%、蔗糖添加量为6%,柠檬酸添加量为0.02%,稳定剂为耐酸CMC与黄胶原(1∶1)的复合稳定剂,添加量为0.2%。     

稳定剂对脱脂搅拌型酸奶粘度影响的研究

介绍了稳定剂对脱脂搅拌型酸奶粘度的影响。粘度是搅拌型酸奶生产过程中最重要的控制项目之一,也是评价酸奶质量的重要指标。通过控制脱脂搅拌型酸奶的粘度,研究其抗剪切能力,进而控制它的口感和稳定性。实验结果表明:分别添加PGA 0.10%、琼脂0.08%、明胶0.20%、果胶0.10%、变性淀粉0.50%浓度时,其抗剪切能力较好。     

花粉酸奶的研究

通过对比研究、正交实验、极差分析等方法，研究了凝固型与搅拌型花粉酸奶的最佳配方。结果表明，对于搅拌型花粉酸奶的影响因素为：花粉的添加量＞乳粉的添加量＞蜂蜜的添加量＞稳定剂的添加量；对于凝固型花粉酸奶的影响因素为：花粉的添加量＞乳粉的添加量＞稳定剂的添加量＞蜜的添加量。搅拌型花粉酸奶的最佳因素水平为(质量分数)：花粉为0．5％；稳定剂为0.5％；乳粉3％；蜂蜜1.2％；凝固型花粉酸奶的最佳因素水平为(质量分数)：花粉为0．5％；稳定剂为0．6％3乳粉3％5蜂蜜1．5％。     

亚麻籽胶在搅拌型酸奶加工中的应用研究

研究了亚麻籽胶、瓜儿豆胶和变性淀粉作为复配稳定剂在搅拌型酸奶中的应用。结果表明,亚麻籽胶与瓜尔豆胶有较好的协同作用,通过三因素二次正交旋转组合设计试验,建立了黏度、凝胶强度与三种稳定剂配比之间的动态模型,得出了三种稳定剂的最佳配比(%)是3:2:20,稳定剂的吨产品成本降低103.5～128.5元,使企业获得可观的经济效益;而且在冷藏条件、保证产品质量不变的情况下,添加复配稳定剂酸奶的保质期可延长至27d。     

复合添加剂在搅拌型银杏大枣酸奶加工中的应用

研究了琼脂、单甘酯和蔗糖酯作为复合稳定剂在搅拌型酸奶中的应用。结果表明,琼脂、单甘酯和蔗糖酯具有较好的协同作用,通过Box-Behnken试验设计,建立了持水力与三种稳定剂配比之间的动态模型,得到三种稳定剂的最佳配比为:琼脂0.31%、单甘酯0.15%和蔗糖酯0.16%,贮存7 d后,酸奶的组织状态细腻、均匀滑爽、无乳清析出、风味和口感均良好。     

蛋白质强化对搅拌型酸奶品质特性的影响

为了研究蛋白质强化对搅拌型酸奶品质特性的影响,以脱脂奶粉(SMP)和乳清浓缩蛋白-80(WPC-80)作为蛋白源,研究了强化不同种类及不同含量(2.7%、3.1%、3.5%、3.9%)的蛋白质强化对搅拌型酸奶感官品质、黏度和持水性的影响。结果表明:用SMP和WPC-80强化原料乳的蛋白质均可提高搅拌型酸奶的感官品质、黏度和持水性;比较同种蛋白源、不同蛋白质强化水平制得的搅拌型酸奶,其组织状态变化明显,风味稍有变化,色泽保持不变;酸奶的黏度和持水性都随蛋白质水平的上升而显著提高。SMP强化蛋白质含量至2.7%时,酸奶的感官品质最好;WPC-80含量则在3.5%时,酸奶的感官品质最好。同一蛋白质水平、不同强化蛋白相比较,WPC-80强化酸奶比SMP有更好的感官品质和更高的持水性,而SMP强化则得到更高的黏度值;从感官评定的黏稠度得分和测得的黏度值对比得出,搅拌型酸奶的黏度并不是越高越好,最佳黏度值在537～712mPa.s之间。实验中搅拌型酸奶的最佳蛋白强化配方为WPC-80强化蛋白质含量3.5%。     

Pectin and Raspberry Concentrate Effects on the Rheology of Stirred Commercial Yogurt

The influence of pectin (0.0–0.5%) and raspberry concentrate (64°B; 0–10%) on the rheological characteristics of commercial stirred yogurt was evaluated using a computer-controlled rotational viscometer. All upward flow curves (shear rate vs shear stress) followed the Herschel-Bulkley model while downward curves showed a linear relationship. The consistency coefficient (upward flow) and apparent viscosity (downward flow) showed a continuously increasing trend with increasing pectin and raspberry concentrate. The rheology of flavored yogurt could be fabricated by post-incubation mixing of stirred yogurt with pectin and raspberry concentrate.     

三种搅拌型酸奶用变性淀粉的特性及应用

研究了3种搅拌型酸奶用变性淀粉——蜡质玉米乙酰化二淀粉磷酸酯(AWMDP)、木薯乙酰化二淀粉磷酸酯(ATDP)、蜡质马铃薯二淀粉磷酸酯(WPDP)的基本性质和应用效果。3种搅拌型酸奶用变性淀粉经95℃处理10min后仍保持膨胀的颗粒状态,但是膨胀的平均粒径大小、吸水能力不同,这主要与淀粉的来源、交联度有关。3种变性淀粉(0.5%,w/w)都使得搅拌型酸奶的表观黏度、持水力和弹性模量(G')增加,同时提高了酸奶的抗剪切变稀性。WPDP在改善酸奶的物理性能上明显优于其他2种变性淀粉。     

Individual and sequential effects of stirring,smoothing, and cooling on the rheological properties of nonfat yogurts stirred with a technical scale unit

Few studies have considered the impact of unit operations during stirred yogurt manufacture because their operational sequence is difficult to replicate at the laboratory scale. The aim of this study was to investigate the individual and sequential effects of stirring in the yogurt vat, smoothing, and cooling on the rheological properties of yogurts, using a technical scale unit simulating some industrial conditions. The yogurts were prepared from a milk mixture that was standardized to contain 14% total solids, 0% fat, and 4% protein, and then homogenized, heated (94.5°C, 5 min), and inoculated at 41°C with the same thermophilic lactic starter. The operating parameters under investigation were 2 stirring durations in the yogurt vat (5 or 10 min), 2 cooling systems (plate or tubular heat exchanger), and 2 smoothing temperatures (38°C for smoothing before cooling; 20°C for smoothing after cooling). Sampling valves were installed at critical points on the technical scale unit so that the effect of each operation on the properties of stirred yogurt could be quantified individually. Syneresis, apparent viscosity, firmness, and consistency were analyzed after 1 d of storage at 4°C. In general, as the yogurts moved through the technical scale unit, the properties of the yogurts (evaluated after 1 d) changed: viscosity increased but syneresis, firmness, and consistency decreased. The individual effects of the operations showed that smoothing and cooling, compared with stirring duration, made the greatest contribution in terms of modifying yogurt properties. The stirring parameters (5 or 10 min) had similar effects on the yogurts. The use of a plate heat exchanger promoted a decrease in syneresis, whereas a tubular heat exchanger had a greater effect in terms of increasing firmness and consistency. The type of cooling system had no effect on stirred yogurt viscosity. Smoothing at 38°C had a greater effect on the increase in firmness, whereas smoothing at 20°C contributed more to a decrease in syneresis and increases in viscosity and consistency. This study confirms that each unit operation has a defined effect on the rheological properties of a nonfat stirred yogurt, which also depends on the operation sequence.     

Effect of calcium on the physical properties of stirred probiotic yogurt

The effect of calcium on the viscosity, firmness, and smoothness, as determined by extent of nodulation, of stirred probiotic yogurt produced by bacterial fermentation was investigated. Standardized milk for yogurt manufacture was prepared, and calcium was added or removed from the system. Calcium was added as Ca²⁺ in the form of CaCl₂ (up to 13.6 mM) or nonionic calcium as Gadocal-K (calcium potassium citrate; up to 49.8 mM). Calcium was removed by chelating with sodium citrate (up to 16 mM) or by cation exchange with Amberlite IR-120 plus (sodium form) resin (up to 10 g/L). Calcium chloride and sodium citrate were added either before or after heat treatment of milk, and nonionic calcium was added before heat treatment. Calcium removal by ion exchange was performed before heat treatment. Neither Ca²⁺ addition nor removal by chelation with citrate resulted in stirred yogurt with viscosity, firmness, and smoothness superior to those of the control yogurt, whereas addition of 49.8 mM nonionic calcium and removal of calcium (5.6 mM or ∼10% of total calcium) by cation exchange improved the firmness and viscosity without affecting yogurt smoothness. The study identified Gadocal-K as a possible source of calcium fortification of stirred yogurt without loss of texture.     

A1与A2β-酪蛋白酸奶产品特性的比较

探究分别含有A1、A2两种β-酪蛋白牛乳制成的搅拌型和凝固型酸奶产品特性的区别。持水力结果表明,A1β-酪蛋白酸奶（凝固型和搅拌型）的持水力大于69%,A2β-酪蛋白酸奶（凝固型和搅拌型）的持水力大于65%。质构特性的结果显示,凝固型酸奶差距更为明显,A1 β-酪蛋白酸奶的硬度和稠度分别比A2 β-酪蛋白酸奶高41.4%和59.8%。此外,A1 β-酪蛋白酸奶黏性优于A2 β-酪蛋白酸奶。流变学特性与微观结构结果显示,A1 β-酪蛋白酸奶的滞后回路面积较A2 β-酪蛋白酸奶小14.6%,说明A2 β-酪蛋白制成的酸奶结构更易于被破坏,网状结构更为稀疏。本实验为A2 β-酪蛋白牛乳在酸奶制品的应用及实际生产提供一定理论支持。     

Effects of seasonal variations on the quality of set yogurt,stirred yogurt,and Greek-style yogurt

We studied the effects of seasonal variations on the quality of stirred yogurt, set yogurt, and Greek-style yogurt over 2 milking seasons in New Zealand. Correlations between the properties of the yogurts, the characteristics of the milk, and the acid gelation properties induced by glucono-δ-lactone, reported in our previous works, were also explored. Set yogurt and Greek-style yogurt from the early season had the highest firmness over the seasons. The yogurt firmness correlated with the gel strength of glucono-δ-lactone-induced acid gels, indicating that the latter could, to some extent, predict the seasonal variations in the firmness of set yogurt. The correlation studies highlighted the potentially important role of the glycosylation of κ-casein in the seasonal variations in the yogurt structures. Yogurt made from mid-season milk had the lowest water-holding capacity, which may have played a part in lowering its firmness and viscosity. Late-season stirred yogurt displayed the strongest resistance to shear-induced thinning, which might arise from the unique viscoelastic properties of late-season yogurt gels.     

利用固定化谷氨酰胺转氨酶生产搅拌型软枣猕猴桃果肉酸奶

研究了利用固定化谷氨酰胺转氨酶生产搅拌型软枣猕猴桃果肉酸奶的工艺条件,即固定化酶添加量30 g/L,接种量3.5%,果肉添加量35 g/L,42℃下发酵3.5 h;与未添加谷氨酰胺转氨酶的酸奶相比,其持水力、表观黏度和贮藏黏度分别提高了139.2%、32.9%和42.9%,乳清析出率降低了38.5%。同游离酶相比,固定化谷氨酰胺转氨酶的操作稳定性较高,连续使用8次,酶活仍保持在80%以上。     

搅拌型酸奶后酸化控制的初步研究

文中针对搅拌型酸奶成熟后在贮存、运输、销售、食用前出现的后酸化现象(postacidification)文中进行了初步研究。在无水乙醇抑制后酸化的实验中,4%的无水乙醇能明显抑制乳酸菌的进一步产酸,且不影响其优良的感官指标。进一步研究发现,每40mL酸奶制品分别添加1.4mL酒精度为38%的汾酒、1.0mL酒精度为62%的高度酒均可明显抑制后酸化现象。文中还尝试了酵母菌抑制后酸化的效果,结果发现,1株从牧区家庭自制酸奶中分离的酵母菌以2.0×107个/mL的浓度,每40mL酸奶制品添加0.1mL不仅可抑制后酸化现象,而且轻微的乙醇发酵改善了酸奶的口味,提高了酸奶的感官品质。经细胞形态、菌落特征、生理生化及产孢子类型可初步判断该酵母菌为异酒香酵母。     

增稠剂对酸奶质地的影响研究

对酸奶的硬度、黏度、凝聚性、保水性进行测定，研究了不同增稠剂对酸奶质地和感官特性的影响。结果表明。果胶、明胶、耐酸CMC、海藻酸钠分别提高了酸奶的黏度，而槐豆胶、瓜尔豆胶、魔芋胶则相反；只有果胶和明胶提高了酸奶的保水力；果胶、明胶时酸奶质地的影响随着浓度的增加而增加。统计结果表明，当增稠剂添加量为0．1％时，不同增稠剂对酸奶的质地存在显著影响；同时．增稠荆浓度对酸奶质地的影响也显著。