No difference in symptoms during challenges with homogenized and unhomogenized cow's milk in subjects with subjective hypersensitivity to homogenized milk

It has been hypothesized that certain consumers tolerate untreated cow's milk, but react to processed (i.e. homogenized and pasteurized) cow's milk although they do not suffer from IgE-mediated cow's milk allergy or lactose intolerance. The aim of the study was to compare the tolerance of unhomogenized and homogenized cow's milk in lactose tolerant adults who had repeatedly experienced better tolerance of unhomogenized than homogenized milk. Forty-four subjects were challenged with homogenized and unhomogenized cow's milk for five days in a randomized, double-blind, cross-over study. No differences in the symptoms during the challenges were found. Roughly half the subjects tolerated the homogenized milk better and the other half tolerated the unhomogenized milk better. The results of this study show no difference in the tolerance of homogenized and unhomogenized milk in adults with self-reported symptoms suggestive of hypersensitivity to homogenized milk.     

乳糖衍生物--功能性甜味剂

乳糖是普通的营养性双糖，但相当一部分人群食用乳糖后呈现过敏症反应，影响了对含乳糖食品的食用。将乳糖进行改性后得到的乳糖衍生物，可以消除或改善部分人群对乳糖的不耐症，增加功能性，以适用更多人群。     

豆蛋白婴儿配方粉的研究

介绍了豆蛋白婴儿配方粉的配方设计特点、设计依据、工艺流程以及该配方的动物喂养试验结果;同时对该配方所设计的主要营养民分也进行了详细讨论。该产品除了普通婴儿可以食用外,尤其适用于患有乳糖不耐症及乳蛋白质过敏症的婴儿。     

低乳糖奶的应用与发展

牛奶是营养丰富、容易消化吸收的天然食品。但是由于乳 糖不耐症的存在,使较多消费者饮用牛奶后会出现消化不 良、腹胀等现象。而低乳糖牛奶的开发满足了乳糖不耐症 患者的乳品消费需求,又改善了其他一些乳制品的加工工 艺条件和产品品质,促进了我国乳制品工业的发展。     

A systematic review and meta-analysis of the effects of pasteurization on milk vitamins, and evidence for raw milk consumption and other health-related outcomes

Pasteurization of milk ensures safety for human consumption by reducing the number of viable pathogenic bacteria. Although the public health benefits of pasteurization are well established, pro-raw milk advocate organizations continue to promote raw milk as "nature's perfect food." Advocacy groups' claims include statements that pasteurization destroys important vitamins and that raw milk consumption can prevent and treat allergies, cancer, and lactose intolerance. A systematic review and meta-analysis was completed to summarize available evidence for these selected claims. Forty studies assessing the effects of pasteurization on vitamin levels were found. Qualitatively, vitamins B12 and E decreased following pasteurization, and vitamin A increased. Random effects meta-analysis revealed no significant effect of pasteurization on vitamin B6 concentrations (standardized mean difference [SMD], -2.66; 95% confidence interval [CI], -5.40, 0.8; P = 0.06) but a decrease in concentrations of vitamins B1 (SMD, -1.77; 95% CI, -2.57, -0.96; P < 0.001), B2 (SMD, -0.41; 95% CI, -0.81, -0.01; P < 0.05), C (SMD, -2.13; 95% CI, -3.52, -0.74; P < 0.01), and folate (SMD, -11.99; 95% CI, -20.95, -3.03; P < 0.01). The effect of pasteurization on milk's nutritive value was minimal because many of these vitamins are naturally found in relatively low levels. However, milk is an important dietary source of vitamin B2, and the impact of heat treatment should be further considered. Raw milk consumption may have a protective association with allergy development (six studies), although this relationship may be potentially confounded by other farming-related factors. Raw milk consumption was not associated with cancer (two studies) or lactose intolerance (one study). Overall, these findings should be interpreted with caution given the poor quality of reported methodology in many of the included studies.     

酶技术在乳品研究中的最新进展

综述了酶技术在牛奶生产,牛奶成分修饰,生物活性肽制备,干酪生产,乳品保鲜等方面的应用。在酶的作用下,牛乳中的乳糖、乳蛋白、苯丙氨酸等可以降解成不耐受机体可以直接吸收利用的成分,防止乳糖不耐症、牛乳蛋白过敏及苯丙酮尿症的发生,以扩大牛奶消费人群。应用酶技术还可以提高乳制品生产的质量和安全性,改进生产工艺过程和改善产品风味。     

Foods for Special Dietary Needs: Non-dairy Plant-based Milk Substitutes and Fermented Dairy-type Products

A growing number of consumers opt for plant-based milk substitutes for medical reasons or as a lifestyle choice. Medical reasons include lactose intolerance, with a worldwide prevalence of 75%, and cow's milk allergy. Also, in countries where mammal milk is scarce and expensive, plant milk substitutes serve as a more affordable option. However, many of these products have sensory characteristics objectionable to the mainstream western palate. Technologically, plant milk substitutes are suspensions of dissolved and disintegrated plant material in water, resembling cow's milk in appearance. They are manufactured by extracting the plant material in water, separating the liquid, and formulating the final product. Homogenization and thermal treatments are necessary to improve the suspension and microbial stabilities of commercial products that can be consumed as such or be further processed into fermented dairy-type products. The nutritional properties depend on the plant source, processing, and fortification. As some products have extremely low protein and calcium contents, consumer awareness is important when plant milk substitutes are used to replace cow's milk in the diet, e.g. in the case of dairy intolerances. If formulated into palatable and nutritionally adequate products, plant-based substitutes can offer a sustainable alternative to dairy products.     

Milk intolerance and microbe-containing dairy foods

The relationship between primary lactase deficiency, the amount of lactose in the diet, and symptoms of intolerance continues to be debated. Primary adult lactase deficiency is common with a worldwide occurrence of near 70%. Lactase-deficient individuals malabsorb lactose but may or may not show intolerance symptoms. The development of symptoms appears to depend on the dose of lactose ingested, whether it is accompanied by a meal or other food, rate of gastric emptying, and small intestine transit time. Lactose loads of 15 g or greater produce symptoms in the majority of lactase-deficient persons. However, when lactose loads of up to 12 g are fed, symptoms can be minimal or absent. Tolerance to yogurt, acidophilus milk, and other microbe-containing dairy foods has been suggested and is thought to be due to either a low lactose content or in vivo autodigestion by microbial beta-galactosidase. Up to 20 g of lactose in yogurt is tolerated well by lactase-deficient persons. Associated with the consumption of yogurt is a three- to fourfold reduction in lactose malabsorption as compared with similar lactose consumption in milk. Improved lactose digestion appears due to autodigestion by microbial beta-galactosidase. This enzyme may be released from yogurt culture by gastric or bile acid digestion. Feeding yogurt that was pasteurized following fermentation, with only trace amounts of microbial beta-galactosidase activity, results in a threefold increase in lactose malabsorption as compared with feeding yogurt with a viable culture. However, pasteurized yogurt also is tolerated well by lactase-deficient persons, suggesting that tolerance of up to 20 g of lactose in yogurt may be independent of lactose malabsorption. The enhanced lactose absorption and tolerance observed with yogurt feeding are not apparent when unfermented acidophilus milk or cultured milk are fed.     

The balance between caseins and whey proteins in cow's milk determines its allergenicity

Cow's milk allergy is quite common in the first years of human life. Protein composition plays an important role in this pathology, particularly the casein/whey protein ratio. It is known that milks from different species have different sensitization capacities although their protein sources are quite similar. Thus, the objective of this work was to compare the allergenicity of native cow's milk and milk with a modified ratio of casein and whey proteins in a murine model of atopy. Twenty-four Balb/c mice were orally sensitized to native cow's milk or modified cow's milk with a casein/whey protein ratio of 40:60. During the sensitization period, the number of mice suffering from diarrhea was significantly higher in the native cow's milk-sensitized group than in the modified milk-sensitized group. Once mice were killed, plasma histamine levels were shown to be significantly higher in native cow's milk-sensitized mice. In addition, cow's milk proteins induced a higher lymphocyte sensitization in the native milk-sensitized mice, with a significant increase in the specific proliferation ratio of these cells.These results suggest that the balance between caseins and whey proteins plays an important role in the sensitization capacity of cow's milk, and its modification might be a way to reduce the allergenicity of cow's milk.     

固定化乳糖酶制备低乳糖牛奶的研究进展

不同来源的β-半乳糖苷酶已经用于水解牛乳或乳清中的乳糖。酶水解乳糖的基本产物为葡萄糖和半乳糖。经水解后的乳糖增加了产品的甜度并使得牛乳适于那些患乳糖不耐症的人群。由于用游离乳糖酶会使牛奶掺入外来蛋白以及使用游离乳酶酶提高了生产成本,从而使乳糖酶的应用受到限制。将乳糖酶固定化后既可以重复使用,又能连续操作,且缩短了处理时间,从而明显降低了使用成本,因此对于乳糖酶的固定化受到了酶学专家的关注。本文简要介绍了乳糖和乳糖酶及其分类、乳糖酶的固定化方法及其应用,包括包埋法、交联法、吸附法、结合法及多种方法的混合使用及国内外的研究现状,并简要介绍了固定化乳糖酶的清洗。     

The nutritional and physiological impact of milk in human nutrition

The nutritional value of milk as an important source of energy, high‐quality protein, calcium, and riboflavin has been recognized for many years. Currently, the widespread use and promotion of milk in the U.S. as well as developing countries has been questioned. This review examines the nutrient composition of dairy products, factors that account for variability in composition of milk, milk processing, preservation, quality control, and contaminants (such as minerals, radionuclides, antibiotics, microorganisms and their metabolites, herbicides, and insecticides) in milk. Consumption patterns for milk and evidence for its nutritional value, especially in children, are presented. Milk consumption has been related to disease or conditions such as atherosclerosis, milk allergy, lactose intolerance, anemia, dental problems, and others. Recent recommendations for dietary changes for individuals in the U.S. and other developed countries could affect the use of milk. In addition, the use of feeding programs in the U.S. and developing countries which are based primarily on milk has been criticized. The preparation of new types of milk designed to offset certain difficulties encountered with cow's milk are now being evaluated in humans.     

响应面法优化低乳糖奶水解工艺

牛奶及乳制品营养丰富,容易消化吸收,人称"白色血液",是最理想的天然食品。近年来我国乳业发展迅速,但与世界平均水平仍存在巨大的差距,制约我国乳业发展的一个重要原因就是乳糖不耐症。利用β-半乳糖苷酶对牛奶进行水解可生成易被人体吸收的葡萄糖、半乳糖及"双歧因子"低聚半乳糖,不仅能解决乳糖不耐症问题,还能增加牛奶的营养价值。本文在单因素初步试验的基础上,以低聚半乳糖合成率为响应指标,通过响应分析法对低乳糖水解工艺进行优化。结果表明,当反应温度为45.3℃、加酶量为2.5mL及反应时间为69.7min时,低聚半乳糖得率达到最大值6.15%。通过乳果糖试剂盒测定水解后低乳糖奶中乳果糖含量,平均含量为158.17mg/L。     

Comparative performance of a mixed strain starter in cow's milk, ewe's milk and mixtures of these milks

Lactococcus lactis ssp. lactis IPLA 947, L. lactis ssp. lactis biovar. diacetylactis IPLA 838 and Leuconostoc citreum IPLA 616 and designed for Afuega'l Pitu cheese manufacture from pasteurized milk was assayed in cow's and ewe's milk, and in mixtures containing 10% and 20% ewe's milk in cow's milk. The evolution of microbial counts, pH, titratable acidity, organic acids and volatile compounds production throughout the incubation period was determined. The use of ewe's milk as a culture medium increased the metabolic activity of the starter culture reflected in a higher lactose consumption, significantly higher acidity and some carbon source-derived organic acids and volatile compounds production, as well as in slightly higher starter strains growth, although the latter was not statistically significant. Thus, it is suggested that ewe's milk or mixtures of ewe's with cow's milk can be satisfactorily used in the manufacture of this traditional cheese. Received: 27 August 1999     

Production,Consumption, and Pricing of Milk and Its Components,

Production and consumption of milk fat, milk protein, and lactose were compared for 1970, 1975, 1979, and 1983 to determine whether production and consumption were balanced and, if not, to determine how balance might be achieved. Ratios of these components in milk produced remained virtually constant from 1970 to 1983. However, increased cheese consumption during this period resulted in increased per capita consumption of fat and protein despite reduced consumption of these components in other dairy products. Because lactose is not in cheese, lactose consumption declined. Because of these changes, imbalances of production and consumption of milk components now exist and are due almost entirely to too much lactose being produced. Because of small variation of lactose percentage, this imbalance could be reduced by increased fat and protein percentages. Milk pricing should encourage this by emphasizing fat and protein (not solids-not-fat). Fat and protein differentials should differ from market to market and should be based on utilization. Milk pricing is reviewed, and a procedure for determining blend differentials is outlined.     

The carbohydrate composition of human milk

The carbohydrate content of breast milk was investigated by capillary gas liquid chromatography. The milk samples obtained from 16 normal lactating mothers contained glucose, galactose, lactose, and 3-fucosidolactose. The content of monosaccharides in breast milk was 2-12 times higher than that in cow's milk. The lactose content amounted to 84-95%, whereas the ratio of alpha- tox beta-froms was within 0.92-0.95%. Breast milk was found to contain alpha- and beta-forms of 2- and 3-fucosidolactose which do not occur in cow's milk. The content of these forms accounted for 3%. The biological role of breast milk carbohydrates is discussed.     

β-Galactosidase activity of commercial lactase samples in raw and pasteurized milk at refrigerated temperatures

Many consumers are unable to enjoy the benefits of milk due to lactose intolerance. Lactose-free milk is available but at about 2 times the cost of regular milk or greater, it may be difficult for consumers to afford. The high cost of lactose-free milk is due in part to the added cost of the lactose hydrolysis process. Hydrolysis at refrigerated temperatures, possibly in the bulk tank or package, could increase the flexibility of the process and potentially reduce the cost. A rapid β-galactosidase assay was used to determine the relative activity of commercially available lactase samples at different temperatures. Four enzymes exhibited low-temperature activity and were added to refrigerated raw and pasteurized milk at various concentrations and allowed to react for various lengths of time. The degree of lactose hydrolysis by each of the enzymes as a function of time and enzyme concentration was determined by HPLC. The 2 most active enzymes, as determined by the β-galactosidase assay, hydrolyzed over 98% of the lactose in 24 h at 2°C using the supplier's recommended dosage. The other 2 enzymes hydrolyzed over 95% of the lactose in 24 h at twice the supplier's recommended dosage at 2°C. Results were consistent in all milk types tested. The results show that it is feasible to hydrolyze lactose during refrigerated storage of milk using currently available enzymes.     

Influence of nonfermented dairy products containing bacterial starter cultures on lactose maldigestion in humans

The effect of nonfermented dairy products containing yogurt or acidophilus cultures on lactose utilization by lactose-maldigesting humans was investigated. Yogurt and acidophilus milk containing 10(7) or 10(8) of Streptococcus thermophilus and Lactobacillus bulgaricus, or Lactobacillus acidophilus, respectively, were prepared using commercially processed 2% low fat milk. Immediately following inoculation, products were refrigerated. Lactose maldigestion was monitored by measuring breath hydrogen excretion at hourly intervals for 8 h following consumption of 400 ml of each test meal containing approximately 20 g of lactose. The yogurt milk containing 10(8) cfu/ml was shown to contain significant concentrations of microbial beta-galactosidase (EC 3.2.1.23; approximately 3 U/ml), which remained stable for at least 14 d at refrigerator temperatures. Breath hydrogen peaks were delayed and significantly lower (approximately 20 ppm at 5 to 7 h) than control values (approximately 70 ppm at 4 h), and intolerance symptoms were eliminated in all subjects. Yogurt milk containing 10(7) cfu/ml demonstrated intermediate breath hydrogen values and was marginally significantly different from control values. Lactobacillus acidophilus strains with varying resistance to bile and total beta-galactosidase-producing potential were also tested. Only one strain, LA-1, which demonstrated low bile resistance and intermediate beta-galactosidase activity, was capable of significantly decreasing breath hydrogen values when 10(8) cfu/ml of milk was consumed.     

Does homogenization affect the human health properties of cow's milk?

During the processing of marketed milk, homogenization reduces fat droplet size and alters interface composition by adsorption of casein micelles mainly, and whey proteins. The structural consequences depend on the sequence of the homogenization and heat treatments. Regarding human health, homogenized milk seems more digestible than untreated milk. Homogenization favors milk allergy and intolerance in animals but no difference appears between homogenized and untreated milk in allergic children and lactose-intolerant or milk-hypersensitive adults. Controversies appear regarding the atherogenic or beneficial bioactivity of some casein peptides and milk fat globule membrane proteins, which might be enhanced by homogenization. In children prone to type I diabetes, early cow's milk consumption would be a risk but no link was observed in the general population and the effect of homogenization has not been studied. In the current context of obesity and allergy outbreaks, the impact of homogenization and other technological processes on the health properties of milk remains to be clarified.     

Analysis of Norwegian milk and infant formulas for ochratoxin A

Samples of organic cow's milk, conventional cow's milk, and cow's milk-based infant formulas were analysed for the occurrence of ochratoxin A by means of an HPLC method. The detection limit was 10ng/l. Ochratoxin A was detected in 6 out of 40 conventional cow's milk samples (range 11-58ng/l) , and in 5 out of 47 organic milk samples (range 15-28ng/l) . No ochratoxin A was detected in any of the 20 infant formula samples. The ochratoxin A levels in cow's milk found in this investigation are sufficient to cause a higher intake of ochratoxin A than the suggested TDI of 5ng/kg bw/ day, e.g. in small children who consume large quantities of milk.     

乳糖在人体内的营养特性

乳糖是乳中惟一的碳水化合物,最易被人体吸收,被人体吸收后可变成多肽、氨基酸和脂肪酸,从而提高乳蛋白和乳脂的利用率。由于乳糖酶的缺乏,许多患有乳糖不耐受的人不能食用乳制品。从乳糖的含量、乳糖的消化代谢过程和乳糖不耐受的分类以及乳糖的营养功能进行阐述。