低乳糖脱脂鲜牛奶的研究

以新鲜的脱脂牛乳为原料,应用乳糖酶对脱脂牛乳中的乳糖进行水解,经杀菌灭酶研制了营养丰富,且具有保健功效的低乳糖脱脂牛奶。乳糖酶在脱脂牛乳中最适水解条件为：水解温度35℃,水解时间2h,乳糖酶添加量1.2g/L,脱脂牛乳经乳糖酶水解,其乳糖水解率达到65%以上。     

乳糖酶研究进展

乳糖酶具有将乳糖水解为半乳糖和葡萄糖,以及半乳糖苷转移作用。乳糖酶主要应用于对乳糖不耐受症的治疗以及对乳制品的加工改良等领域。许多患有乳糖不耐受症群体的体内缺少乳糖酶,使得乳糖不耐受症的患者不能在小肠内将乳糖分解,     

乳糖酶及其在动物体内活性变化的影响因素研究进展

乳糖酶可将乳糖水解为机体极易吸收的两种单糖,葡萄糖和半乳糖。而乳糖是幼龄哺乳动物主要能量来源,乳糖酶对乳糖消化吸收起着至关重要的作用。乳糖酶在食品工业以及治疗人类乳糖不耐症上得到了广泛应用,动物乳糖酶的研究也引起人们的关注。文章就乳糖酶的来源、酶学特性、作用原理、动物体内乳糖酶活性变化及其影响因素等进行综述。     

帝斯曼乳糖酶产品为乳糖不耐受的中国消费者带来福音

乳制品是人体获取蛋白质及钙的良好来源，但由于我国乳糖不耐症人群所占比例较高，阻碍了乳制品的推广。世界健康组织数据表明，乳糖不耐症或乳糖酶缺乏的人群在中国占85%以上。乳糖酶可以使乳糖水解为葡萄糖和半乳糖，通过降低乳糖含量使乳糖不耐症人群能够少量或正常地摄入乳制品。     

低乳糖营养乳的研制

低乳糖营养乳是利用乳糖酶水解牛乳中的乳糖，并强化维生素A、维生素D、钙及牛磺酸和低聚异麦芽糖等营养元素的牛乳。该牛乳解决了部分人有乳糖不耐症或乳糖酶缺乏的问题。该产品具有营养丰富全面，口味香甜纯正，稳定性能好的特点。     

贮存温度对液体乳糖酶活性的影响

乳糖酶,别名β-半乳糖苷酶,主要应用于乳品行业,其主要作用是使乳糖水解为葡萄糖和半乳糖。由于乳糖酶存在受热降解的特性,在对其进行贮存的过程中,乳糖酶的活性会随贮存温度的变化而变化。对不同温度条件下贮存的液体乳糖酶活性进行了对比检测与分析。     

低乳糖牛乳的研制

本论文主要探讨乳糖酶水解生鲜牛乳中乳糖的工艺。实验证明：加入１０００ＮＬＵ／Ｌ和２０００ＮＬＵ／Ｉ。乳糖酶在３７℃温度下３ｈ和１．５可将生乳中的乳糖含量降低５０％左右，在低温９℃下１８ｈ和１５ｈ也能达到同样的效果，而且，由于乳糖被分解为葡萄糖和半乳糖，使得牛乳甜度增加，改善了风味。     

乳糖酶的作用及其在乳品工业中的应用

乳与乳制品是营养成分十分丰富的天然食品，其营养价值早已得到了世人的公认，然而美中不足的是由于部分人体内缺乏乳糖酶导致的乳糖不耐受现象，影响了他们对乳制品的正常摄入，这在很大程度上制约了乳制品在人们日常生活中的普及和人体对乳制品营养成分的消化吸收。随着现代生物科学技术的发展，人们利用乳糖酶定向水解牛乳中大量的乳糖，从而使得从根本上解决乳糖不耐受这一困绕世人多年的医学难题成为可能。本文就乳糖酶在乳制品加工业生产中的应用作一简要论述，以期对大家有所启迪和帮助。     

固定化乳糖酶在低乳糖乳制品中的应用

乳糖不耐症及低乳糖乳制品口感问题是制约乳制品消费增长的重要因素。通过固定化乳糖酶分解牛乳中的乳糖,同时调整配方,制备出口感佳、营养丰富、成本低的低乳糖乳制品。结果表明,固定化后的乳糖酶在温度50.00～70.00℃、pH值6.7左右时,具有较高的酶活力,稳定性好,金属离子对固定化酶活力影响较小。通过响应面法优化出制备低乳糖乳制品的最佳条件为:温度50.33℃,时间181.99 min,固定化乳糖酶添加量1.28 g/L,乳糖水解率为83.98%,固定化乳糖酶可重复使用8次。通过正交试验及感官评价,确认低乳糖乳制品的最佳添加剂配方为:玛卡粉0.08%,椰粉3.00%,乳清蛋白粉1.80%和果葡糖浆2.00%,为低乳糖乳制品的规模化生产奠定了基础。     

乳糖酶的特性及其在乳品工业中的应用

乳和乳制品的营养价值早已得到世人的公认,然而由于部分人群体内缺乏乳糖酶导致的乳糖不耐受现象,影响了人们对于乳制品的正常摄入,这在很大程度上也就制约了乳制品在人们日常生活中的普及和人体对乳制品营养成分的消化吸收.随着现代生物技术的发展,人们可利用乳糖酶定向水解牛乳中大量的乳糖,使得从根本上解决乳糖不耐受这一难题成为可能.本文就乳糖酶的来源、     

Suspected primary lactose intolerance in neonatal foals

The intestine of neonatal mammals must be able to secrete lactase enzyme to hydrolyse lactose in its mother's milk. Failure to secrete lactase results in failure to digest lactose. This results in osmotic diarrhoea, weight loss, failure to thrive, lethargy, colic and abdominal distension. Lactose intolerance may occur secondarily to intestinal bacterial infection. Primary lactose intolerance is recognised in human infants. Here we report 2 cases of suspected primary lactose intolerance in foals. The foals responded well to oral administration of exogenous lactase enzyme.     

Glucose and galactose absorption after ingestion of milk containing hydrolysed lactose in calves with diarrhoea

Ten calves which had contracted acute diarrhoea caused by rotavirus, coronavirus and Cryptosporidium were used to test the hypothesis that feeding lactose-hydrolysed cow's milk instead of unprocessed cow's milk improves sugar absorption in diarrhoeic calves. The animals were rehydrated with an orally administered solution containing electrolytes and glucose. Thereafter the calves received one test meal of whole fresh cow's milk whose lactose had been hydrolysed by added lactase and one test meal of unprocessed cow's milk at an interval of 24 h in a cross-over design trial. In comparison with unprocessed milk, the intake of milk containing hydrolysed lactose resulted in a slight decrease of mean breath hydrogen concentration (P = 0.18), but also a slight decrease of mean blood galactose concentration (P = 0.14). There was no treatment effect on mean plasma glucose concentration. Peak plasma glucose and blood galactose concentration tended to be delayed after the intake of lactose-hydrolysed milk, which implies that gastric emptying was probably delayed. The results show that feeding milk which contains hydrolysed lactose does not significantly improve lactose utilization in calves that are suffering from benign infectious diarrhoea.     

Laboratory evaluation of malassimilation in horses

Malassimilation should be suspected in horses with weight loss in spite of a good appetite. Malassimilation is usually confirmed with oral glucose or D-xylose absorption tests, whereas the oral lactose tolerance test can be used to evaluate lactase deficiency in foals. Once malassimilation is confirmed, other diagnostic tests such as abdominocentesis, rectal mucosal biopsy, or exploratory laparotomy with intestinal biopsies may determine the etiology of malassimilation.     

Secondary lactose intolerance in a neonatal goat

A 2-week-old Toggenburg kid was evaluated for persistent diarrhea and poor body condition. The herd had high morbidity and mortality associated with diarrhea in neonatal kids. Lactose intolerance was diagnosed on the basis of results of a lactose tolerance test and glucose absorption test. Clinically normal herdmates were used as control animals. The kid responded to lactase supplementation. Cryptosporidium organisms were detected in feces of several affected kids during episodes of acute diarrhea. Lactose intolerance was presumed to have developed secondary to intestinal cryptosporidiosis.     

低糖高纤维常温发酵乳工艺及配方优化

以柑橘纤维、甜菜纤维和琼脂构建低糖高纤维常温发酵乳体系,探究不同添加量组合下产品质构及感官品质。同时利用乳糖酶和Sweety T-1发酵剂分解产品中全部乳糖,并转化为甜度更高的葡萄糖,从而提高低糖发酵乳的甜度。结果表明：添加3%柑橘纤维、0.2%琼脂和1%甜菜纤维可构建质构优良、稳定性好且感官评分高的低糖高纤维常温发酵乳体系;在不添加其他增甜物质的基础上,接种200 U/L Sweety T-1发酵剂,42 ℃发酵12 h,同时加入1 600 BLU/L乳糖酶,利用乳糖酶和Sweety T-1发酵剂的协同作用分解全部乳糖,产生2.5%葡萄糖来提高产品甜感,真正实现长保质期发酵乳的低糖和高纤维。     

Jejunal mucosal lactase activity from birth to three weeks in conventionally raised calves fed an electrolyte solution on days 5, 6 and 7 instead of milk.

The purpose of this study was to evaluate the effect of withdrawal of lactose from the diet for 72 hours on lactase activity in the jejunal mucosa of conventionally raised calves. The descending portion of the duodenum of six Holstein calves less than 24 hours old was cannulated. The calves were fed milk except on days 5, 6 and 7 when they were given the same volume of an electrolyte solution. Sequential biopsy specimens of the proximal jejunal mucosa were obtained for three weeks and the lactase activity determined. Lactase activity was highest on day 1 and a trend toward decreased lactase activity from birth until three weeks was observed. Mean lactase activity was significantly (p less than 0.05) higher for days 1, and 3 compared to days 9, 13 and 17. The withdrawal of milk and replacement by an electrolyte solution during three days had no significant effect on jejunal mucosal lactase activity in neonatal calves.     

Interaction between lactic acid bacteria and yeasts in airag,an alcoholic fermented milk

The interaction between nine lactic acid bacteria (LAB) and five yeast strains isolated from airag of Inner Mongolia Autonomic Region, China was investigated. Three representative LAB and two yeasts showed symbioses were selected and incubated in 10% (w/v) reconstituted skim milk as single and mixed cultures to measure viable count, titratable acidity, ethanol and sugar content every 24 h for 1 week. LAB and yeasts showed high viable counts in the mixed cultures compared to the single cultures. Titratable acidity of the mixed cultures was obviously enhanced compared with that of the single cultures, except for the combinations of Lactobacillus reuteri 940B3 with Saccharomyces cerevisiae 4C and Lactobacillus helveticus 130B4 with Candida kefyr 2Y305. C. kefyr 2Y305 produced large amounts of ethanol (maximum 1.35 g/L), whereas non‐lactose‐fermenting S. cerevisiae 4C produced large amounts of ethanol only in the mixed cultures. Total glucose and galactose content increased while lactose content decreased in the single cultures of Leuconostoc mesenteroides 6B2081 and Lb. helveticus 130B4. However, both glucose and galactose were completely consumed and lactose was markedly reduced in the mixed cultures with yeasts. The result suggests that yeasts utilize glucose and galactose produced by LAB lactase to promote cell growth.     

Lactose Intolerance in a Calf

Lactose intolerance was identified as the cause of bovine neonatal diarrhea. Glucose and xylose oral absorptions were normal whereas lactose absorption was reduced relative to normal calves. Lactase deficiency is common in people but rarely reported in animals. The treatment of whole milk with lactase alleviated the diarrhea.     

Effect of levels of starch,fiber, and lactose on digestion and growth performance of early-weaned rabbits

The effect of source of carbohydrate on gut histology, digestion efficiency, and growth performance in early-weaned (25 d) rabbits at the starter period (25 to 39 d) was investigated. Six diets were factorially arranged to study the effect of partial substitution of starch (0, 25, or 50%) by lactose at two levels of fiber (30 or 36% NDF). Diets were formulated to meet or exceed essential nutrient requirements of growing rabbits. A feeding trial was conducted to measure the effect of treatments on growth performance in 252 rabbits that were fed the experimental diets in the starter period and thereafter received a common feed until 60 d of age. Fecal apparent digestibility was determined at 35 d of age in nine animals per diet. The four diets with extreme lactose content were used to determine ileal apparent digestibility of starch and lactose (nine replicates per diet), weights of stomach and cecum, stomach pH, cecal fermentation traits, amylase and disaccharidase activities (10 animals per diet), and jejunal morphology (six animals per diet). Weaning increased (P < 0.001) amylase activity by 59% but decreased (P < 0.001) maltase, sucrase, and lactase activities by 30, 48, and 72%, in parallel with a reduction of villus height by 19%. Dietary NDF level did not affect either jejunal morphology or sucrase and lactase activities but increased amylase (P = 0.05) and maltase (P < 0.001) activities by 22 and 92%, respectively. Substitution of starch by lactose had no effect on jejunal morphology or enzymatic activity. Ileal lactose and starch digestibility were not affected by dietary NDF or lactose level and averaged 73.8 and 90.8%, respectively. Substitution of starch by fiber and lactose affected ileal flux of starch plus lactose (by -0.5 and +1.7 g/d) and cecal pH (by +2.1 and -2.8%, respectively). Fecal NDF digestibility was relatively low (23.1% on average) and was not affected by treatments, whereas that of lactose and starch was almost complete. An increase of dietary NDF level led to an impairment of ADG and feed efficiency in the starter (P < 0.002) and in the overall (P < 0.03) fattening period. Substitution of starch by lactose linearly decreased (P < 0.001) feed efficiency in the starter period and linearly increased (P < 0.001) diarrhea incidence in the fattening period. The results indicate that digestive capability of early-weaned rabbits is limited and should be taken into account to establish optimal levels and sources of carbohydrates in the starter diet.