水溶性大豆多糖和果胶作为酸性乳饮料稳定剂的研究

通过改变酸性乳饮料的加工工艺比较了大豆多糖和果胶在稳定酸性乳饮料时的差异.结果表明,温度和调酸的顺序对添加了大豆多糖的酸性乳饮料稳定性的影响比对添加了果胶的酸性乳饮料稳定性的影响更为显著.在0℃时调酸和调酸之后均质的条件下,添加有0.40%大豆多糖的酸性乳饮料的稳定性最好,沉淀率最低为0.69%;而添加有0.35%果胶的酸性乳饮料的沉淀率为0.71%.而且进一步验证了大豆多糖能在pH值为3.4～4.4范围内稳定酸性乳饮料,而果胶只能在pH值为3.6～4.4范围内稳定酸性乳饮料.     

可溶性大豆多糖在酸性乳饮料中的应用工艺条件研究

目的研究不同工艺条件对含可溶性大豆多糖的酸性乳饮料的稳定性的影响。方法以产品离心沉淀率、粒径分布以及稳定性扫描结果为指标,测定可溶性大豆多糖浓度、调酸温度、调酸终点p H和调酸前后均质工艺对产品稳定性的影响。结果样品稳定性随着可溶性大豆多糖浓度增高而上升,当大豆多糖浓度大于0.3%时稳定性随大豆多糖浓度升高变化不大;样品稳定性随着调酸温度升高而降低;样品在调酸终点p H为3.75时最稳定;对于相同大豆多糖添加量的体系,仅在调酸后进行均质的样品稳定性较好。结论对于蛋白质含量约为0.7%的酸性乳饮料,大豆多糖最优添加量为0.3%,调酸温度应在20℃以下。如果需要在调酸前增加一道均质工艺可能需要调整大豆多糖用量。酸性乳饮料稳定性受调酸终点p H影响。     

可溶性大豆多糖对于配制型酸性乳饮料稳定效应影响因素研究

利用离心沉淀率、粒径、LUMisizer稳定性分析仪研究了可溶性大豆多糖(Soluble soybean polysaccharides,SSPS)添加量、乳饮料中蛋白质含量、SSPS和果胶复配比例对配制型酸性乳饮料稳定性的影响。结果表明,随着SSPS添加量的增大,配制型酸性乳饮料的离心沉淀率和平均粒径均逐渐减小,LUMisizer稳定性逐渐增强,0.4%的SSPS添加量对于含蛋白量1.0%的酸乳体系稳定效果最好;随着蛋白质含量的增加,饮料稳定性逐渐变差,0.4%的SSPS只能稳定蛋白质含量不超过2.0%的乳饮料;SSPS与果胶在酸性乳饮料中可起到协同增强稳定性的作用,当体系中添加0.1%的SSPS和0.3%的果胶时,酸乳体系稳定性最好。     

粒径分析法研究稳定剂对含乳饮料稳定性的影响

研究水溶性大豆多糖(SSPS)、羧甲基纤维素钠(CMC)和高酯果胶(HMP)在含乳饮料中的粒径分布和离心沉淀率。结果表明：在SSPS、CMC和HMP的质量分数大于0.3%时,酸性含乳饮料的体系开始趋于稳定,当HMP添加量为0.3%、SSPS和CMC的添加量分别为0.5%时,含乳饮料体系稳定性最好,而且粒径分析与离心沉淀率结果相一致。通过分析含乳饮料的粒径分布和离心沉淀率可以快速、准确的判断所添加稳定剂的含量在含乳饮料体系中应用的可行性。     

羧甲基纤维素钠及酸性乳饮料加工工艺对其稳定性及粒径分布的影响

研究了羧甲基纤维素钠（CMC）及酸性乳饮料加工工艺对其稳定性及粒径分布的影响。通过离心沉淀法检测酸性乳饮料的稳定性．对影响稳定效果的主要加工工艺进行了试验。同时测定了这些加工工艺对产品粒径分布的影响,并分析了体系粒径分布与产品稳定性之间的关系。结果表明,CMC添加量、pH值、均质压力、调酸温度等因素都会影响酸性乳饮料的稳定性和粒径分布,其中CMC添加量和均质压力对结果影响明显,调酸温度次之,pH值对结果影响最小。     

调酸性乳饮料的简化加工工艺

介绍了调酸性乳饮料的简化加工工艺,以及这种工艺的特点和主要质量控制点.     

CMC冷化料工艺在调酸型含乳饮料生产中的应用

酸性乳饮料是以牛乳或还原乳为主要原料,乳酸菌发酵、稀释、调酸,或不发酵直接用有机酸将牛乳的pH值调为3.8~4.2后调味制成营养丰富、色泽宜人、风味芳香而倍受广大消费者喜爱的一种饮料。调酸型乳饮料占有市场份额非常巨大。由于酸性乳饮料的pH低于牛乳中酪蛋白的等电点,导致酪蛋白胶束间的静电排斥作用减弱,因而酪蛋白有形成更大颗粒而沉淀的趋势。在生产中,产品质量难以控制,易出现絮状、分层、沉淀等现象,且货架期短。在酸性乳饮料中添加羧甲基纤维素钠(Carboxymethyl Cellulose Sodium,CMC)能够使体系形成羧甲基纤维素一酪蛋白颗粒的复合体,避免颗粒间的聚合作用,使酪蛋白胶束颗粒得以稳定地分散,提高产品的稳定性。与以往的生产工艺相比应用CMC冷化料技术在在原口感风味可接受的前提下,可以使调酸型含乳饮料稳定性增强,同时能降低能耗、节约生产成本。     

直接调酸型乳饮料的研制

以鲜牛乳为主要原料研究所了调酸型乳饮料的配方及制作工艺。     

水溶性大豆多糖与大豆果胶的提取及功能特性研究进展

大豆作为我国传统作物,有很长的耕作历史,但由于国内对大豆的深加工起步较晚,对于深加工的副产物豆皮、豆渣的研究利用较不充分。而豆皮、豆渣中富含膳食纤维,是水溶性大豆多糖(soluble soybean polysaccharides,SSPS)和大豆果胶(soybean pectin,SP)的良好来源。SSPS和SP结构和性能相似,在食品工业中具有很高的应用价值。在国外,对SSPS和SP的研究较早,对SSPS和SP的提取工艺、分子结构组成、流变学性质、乳化性质以及稳定酸性乳饮料的机制等方面已经做了不少的研究。国内起步晚,SSPS和SP的工业化生产始终未成健全体系,SSPS及SP的提取工艺存在不成熟、提取纯度不高及功能性质不稳定等问题。本文对SSPS和SP的结构、生物活性、以及在食品工业中应用的研究进展进行了综述。     

可溶性大豆多糖与果胶对酸化乳饮料的稳定机制对比

酸性乳饮料存在乳蛋白沉淀和乳清析出的问题,需要添加果胶等多糖作为稳定剂。可溶性大豆多糖（SPSS）具有黏度低、溶解性好和口感清爽等优点,但其稳定酸性乳饮料的机制尚不明确。作者以脱脂乳为主要原料的调酸型和发酵型酸性乳饮料为研究对象,通过测定LUMiSizer不稳定指数、SEC-HPLC（分子体积排阻高效液相色谱法）表征的复合物形成量、粒径、ζ-电位及冷藏14 d贮藏稳定性等指标,对比研究SPSS与果胶稳定酸化脱脂乳、酪蛋白和乳清蛋白等3种乳蛋白体系的机制差异。结果显示,对于3种直接酸化的乳蛋白体系,2 g/L的SSPS无法与酪蛋白形成有效复合物并稳定体系,2 g/L果胶对3种乳蛋白均无法有效形成复合物且不能良好稳定体系,其余质量浓度的多糖均能与3种10 g/L乳蛋白形成复合物,并且冷藏14 d贮藏稳定性良好。对于发酵脱脂乳,只有添加6 g/L果胶时才能被有效稳定。乳清蛋白和酪蛋白的稳定性结果并不能预测发酵脱脂乳的稳定效果。平均粒径结果显示,3种直接酸化的乳蛋白体系的粒径均远小于发酵酸化体系;增加SSPS添加量无法有效降低发酵脱脂乳的平均粒径,但对于直接酸化的3种乳蛋白体系、发酵酸化乳清蛋白和酪蛋白,随着SSPS添加量的增加,平均粒径都显著下降;果胶降低酸化乳蛋白粒径的能力远不如SSPS。上述结果说明,酸化乳蛋白的粒径是影响多糖复合物形成的要素之一,在复合物有效生成的前提下,体系黏度可能也是影响体系稳定性的重要因素。离心稳定性不能表征长期存放稳定性。对于直接酸化的乳蛋白体系,复合物形成量和平均粒径可能对于预测长期存放稳定性更有意义;对于发酵酸化的乳蛋白体系,平均粒径和黏度可能对于预测长期存放稳定性更有价值。     

可溶性大豆多糖对酸性乳饮料稳定性影响的研究

该文主要研究可溶性大豆多糖（SSPS）对配制型酸乳及发酵型酸乳饮料稳定性的影响。通过测定酸性乳饮料的离心沉淀率,分别研究单一使用SSPS及SSPS、CMC和HMP复配后对配制型酸乳饮料稳定性的影响。同时,还研究了单一使用SSPS及SSPS和CMC复配后对发酵型酸乳稳定性的影响。结果表明,配制型酸乳最终pH值为3．9时,添加0．4％的SSPS或添加0．3％的SSPS和0．1％的CMC,具有良好的稳定性;正交试验结果表明,复合添加0．3％的SSPS、0．05％的CMC、0．4％的HMP配制型酸乳的稳定性较好;发酵型酸乳的最终pH值为4．0时,添加0.4％的SSPS或添加0．1％的SSPS和0．3％的CMC,具有良好的稳定性。     

The stabilizing behaviour of soybean soluble polysaccharide and pectin in acidified milk beverages

The mechanisms of stabilization of soybean soluble polysaccharide (SSPS) and high methoxyl pectin (HMP) in acidified milk drinks were studied focusing on the differences in behaviour between the two polysaccharides. The changes in casein micelles size during acidification with glucono-δ-lactone or by direct acidification were measured using light scattering. When HMP was added to skim milk before acidification, pectin adsorbed on the surface of the casein micelles via electrostatic interactions and prevented casein aggregation. Results suggested that adsorption of pectin occurred from the beginning of acidification and somewhat affected the rearrangement of casein micelles in the pH range between 5.8 and 5.0. On the other hand, SSPS, at concentrations up to 2% (w/w), did not interact with caseins at pH >4.6. At pH <4.2 SSPS showed better stabilizing properties than HMP. In addition, between pH 4.2 and 3.2, SSPS-stabilized acid dispersions were not affected by pH, while dispersions homogenized with pectin showed a size distribution that depended on pH. The differences in structure between SSPS and HMP account for the unique functionalities of the two polysaccharides in acid milk systems.     

Extraction and characterisation of pectin polysaccharide from soybean dreg and its dispersion stability in acidified milk drink

In this study, pectin polysaccharide (SDPP) was obtained from soybean dreg (26.2% yield), and characteristics of SDPP were compared with those of soybean soluble polysaccharides (SSPS) and citrus pectin (HMP). The galacturonic acid and molecular weight of SSPS, SDPP or HMP were 11.8%, 40.6% or 70.2% and 112, 446, or 440 kDa. SDPP had similar viscosity and protein content to SSPS, and functional groups and linear structure to HMP. SSPS, SDPP or HMP differed in particle size of 260, 467 or 1195 nm and ζ–potential of −5.8, −14.6 or −23.5 mV at pH 4.0. The precipitation of acidified milk drink (AMD) was 6.31% without stabiliser or below 1.75% with 0.4% SDPP at pH 3.6–4.6. These results suggested that SDPP combines the structure and characteristic of HMP and SSPS, and AMD with SDPP had great stabilising behaviour at wider pH range (pH 3.6–4.6).     

Characterization and functional properties of soybean high-molecular-mass polysaccharide complex

Soybean soluble polysaccharide (SSPS), extracted from the by-product obtained during isolation of soybean protein, is an anionic polysaccharide that stabilizes milk proteins under acidic conditions. We developed a high-molecular-mass complex of SSPS cross-linked via phosphate (SSPS-HC; absolute molecular weight = 2850 kg/mol, radius of gyration = 106 nm), and found that it has different protein stabilization properties when compared with the original SSPS (absolute molecular weight = 550 kg/mol, radius of gyration = 36 nm). The objective of this work was not only to study the rheological properties of SSPS-HC, but also clarify its protein-stabilizing properties in comparison with SSPS; if molecular mass or negative charge affected protein dispersion. Irrespective of high-molecular-mass, SSPS-HC possessed similar rheological properties to SSPS such as low viscosity in aqueous solution. The absolute negative charges of SSPS-HC measured by a zeta potential analyzer at pH range of 2.0–7.0 were higher than those of SSPS. Acidified milk drinks prepared with 8.4% non-fat milk solids and 0.4% SSPS-HC or SSPS showed low viscosity and small protein particle size, and did not aggregate for 14 days. The thickness of the hydrated layer, which was formed on the surface of protein particles by SSPS molecules measured after hemicellulase treatment with DLS (dynamic light scattering), was estimated to be about 89 nm for SSPS-HC and 33 nm for SSPS. These numerical values were in good relation to the molecular diameter of SSPS-HC and SSPS in aqueous solution measured by DLS and AFM image, and suggested that protein particles were dispersed and the hydrated monolayer made on the surface of protein particles by SSPS-HC or SSPS molecules prevented aggregation. However, stabilizing pH ranges were different with stability of SSPS-HC at pH range of 4.0–4.8 and stability for SSPS at pH range of 3.6–4.2. In addition to the difference in the molecular mass and absolute negative charge, the phosphate groups of SSPS-HC were possibly influenced on the protein-dispersing property approximately at isoelectric point of milk protein; SSPS-HC prevent aggregation of casein by accelerating solubility of calcium phosphate under acidic conditions as is already reported in the starches phosphorylated.     

基于模糊数学评价的黑枸杞百香果乳饮料研制及抗氧化性研究

以百香果、黑枸杞和纯牛奶为原料制备乳饮料,利用单因素、模糊数学评价和响应面法,优化黑枸杞百香果乳饮料的工艺条件,并测定其抗氧化性。结果表明,黑枸杞百香果乳饮料最佳工艺条件为：纯牛奶77%,百香果汁5%,黑枸杞汁11%,蔗糖7%,增稠剂0.06%,菌种接种量0.003%,发酵时间为6.5 h。此优化条件下,乳饮料呈淡黄色,无乳清析出,不分层,具有百香果和黑枸杞的清香和乳饮料特有风味,感官评分8.96分,蛋白质含量3.08 g/100 g。该乳饮料有一定的抗氧化活性,对DPPH自由基的最大清除率为73.7%,该乳饮料各项微生物理化指标均符合相关国标要求。     

Prediction and Characterization of Normal and Vat-Failed Cottage Cheese

An acidification-heat-coagulation test has been developed for predicting cottage cheese vat-failure potential of milk. Milk is fist acidified to pH 5.06 at 10°C and then heated at a slow rate (1°C increment per min). Poor quality acidified milk (> 10⁴ CFU/ml) forms small curds at 37°C and below. Good quality acidified milk (< 10⁴ CFU/ml) will form small curds at higher temperatures. By this procedure cottage cheese vat-failure potential of milk containing different levels of psychrotrophs can be predicted. Normal and vat-failed cottage cheese curds are characterized by % of grit in cottage cheese and amount of curd fines in whey.     

Simultaneous determination of B-group vitamins in enriched Brazilian dairy products

In addition to serving as good natural sources of vitamin B(2), milk and milk products are currently being enriched with the vitamins B(1), B(2), B(6), and nicotinamide in Brazil. The objective of this research was to evaluate the levels of enrichment of these products according to their availability in supermarkets in the Campinas (SP, Brazil) region. The separation of the vitamins was carried out on a C 18 column with gradient elution with acetonitrile and aqueous phase. Detection of vitamins was effected in the ultraviolet region and quantification by an external standard. The levels of vitamin B(2) determined in powdered whole milk, skimmed milk powder, and one brand of flavored lactic beverage, were practically double those stated on the packages. The same occurred with vitamins B(6) and PP (nicotinic acid + nicotinamide), when determined in the same lactic beverage and with vitamin B(6), determined in acidified milk. The high levels of vitamin B(2), naturally present in whole milk, and the predominance of the free form, allowed for the determination of this vitamin in non-enriched milk.     

柳松菇抽提物对乳酸菌发酵性状的影响

将柳松菇抽提物添加到脱脂乳中，以嗜热链球菌和嗜酸乳杆菌为发酵剂制成发酵乳，考察柳松菇抽提物对发酵乳的凝乳时间、凝乳效果、在发酵及贮存过程中乳酸菌的生长、滴定酸度、pH值、黏度及感官性状等的影响。结果表明，5％的添加量能明显促进乳酸菌在乳中的生长，提高产酸速率，缩短凝乳时间，增强凝乳效果，改善发酵乳品质。