米乳汁饮料的研究

我国是大米生产与消费的大国。限于现有的碾米技术。稻谷加工过程中通常产生25～30%的碎米,其中小碎米占1.5～3.0%。本研究利用大米加工中廉价的副产品——碎米为主要原料(大碎米或小碎米均可),合理利用了传统的酒酿工艺,研制出具有传统酒酿风味的新型米乳汁饮料。     

乳汁入馔好处多

乳汁富含婴幼儿生长发育的各种营养物质,而且有大量抗病作用的免疫球蛋白。古人称之为“仙人酒”。《本草纲目》中说:乳汁是返老还童的良药,喂儿疗疾的琼浆。” 乳汁可以滋阴养血,补五脏,益心气,滋脑髓,止消渴,延年益寿。现代医学研究,人乳汁中含营养价值很高的蛋白质、脂肪等多种营养物质。含有乳清酸,能使胆固醇降低。牛羊乳也有类似作用,可抗病保健,促进生长发育。婴幼儿以母乳喂养为最好。用乳汁烹调菜肴,可作中老年保健食品,又可作为各种疾病的辅助治疗。     

乳汁乃是仙家酒

哺乳动物以胎生,产乳汁哺育后代而得名,于是,乳汁就成了人类和其它哺乳动物脱离母体后首先得到的食物。新的生命单靠乳汁就能满足营养需要和维持一切生命活动了。所以,自古以来就有不少人认为,乳汁中存在着一种神秘的东西。基督教把乳汁喻之为天宫的食物,     

瘦素与癌症

综述瘦素的生物学特性、作用机制及与癌症的关系。     

米乳汁发酵饮料的研究

以大米或碎米为原料，根据中国传统酒酿的制备原理，研制出一种新型的米乳汁饮料，该产品具有牛乳的外观，酒酿的风味和碳酸水的口感，市场前景广阔。适宜的发酵条件是２８℃￣５５ｈ或３０℃￣６５ｈ。产品含２０％固形物，１５．４５％还原糖，０．５２％有机酸和１．５％乙醇。     

调味新品：南乳汁的生产技术

0 概述在浙江省数百家酿造调味品企业中,绍兴咸亨食品厂率先推出独家生产的调味新品——南乳汁。该产品采用红南乳原汁再配以天然红曲、绍兴酒等经再发酵而成。产品色鲜红、含酒香及红南乳特有香气、味鲜甜。富含氨基酸、葡萄糖及其它多种营养成分,有和胃、健脾、消肿的功效,是酒楼、饭店及家庭烹饪肉类、水产类和蔬菜类等菜肴的理想调料。其中用南乳汁烧肉叫“南乳肉”系绍兴地方传统名菜。     

乳汁中的促红细胞生成素及其对婴幼儿的生理作用

本文简介乳汁EPO的结构、功能及其测定方法,重点关注母乳EPO影响新生幼仔生理功能的研究进展,这些研究显示:母乳EPO在新生幼仔体内红血球生成、肠道发育、神经营养以及免疫调节等方面均有重要作用。     

乳汁中超氧化物歧化酶的测定及其相关问题的研究

本文采用连苯三酚自氧化方法对人和某些动物的乳汁中所含有的超氧化物歧化酶活力进行了检测。发现人乳平均每毫升为７．１单位，动物乳在３．２－６９．６Ｕ／ｍｌ。乳汁中ＳＯＤ活力是猪乳＞狗乳＞人乳＞牛乳。另外，向未经任何处理的牛原乳汁中添加牛红细胞ＳＯＤ，则可发同外源加入的ＳＯＤ酶将失去原有活力，并初步证明使外源ＳＯＤ失活的因子为乳汁中大分子组分。     

Leptin affects prolactin action on milk protein and fat synthesis in the bovine mammary gland

Leptin, a protein hormone produced and secreted predominantly by white adipose tissue, has a critical role in the regulation and coordination of energy metabolism. Identification of leptin in the milk of several mammals, including humans, led us to investigate its presence and regulatory effect in the cow mammary gland. The expression of leptin receptor in tissue culture of lactating mammary gland was augmented approximately 25 times by prolactin, but had no effect on virgin calf mammary tissue. Expression of leptin in tissue culture from mammary glands of lactating cows was enhanced 2.2-fold by prolactin. No effect of prolactin on leptin and leptin receptor expression was found in mammary gland tissue culture from calves. Leptin-enhanced fatty acid synthesis in the presence of prolactin, but had no effect without presence of prolactin. A similar pattern was found in the expression of alpha-casein and beta-lactoglobulin in mammary gland explants from a lactating cow. Our findings indicate that leptin plays an important role in mammary gland lactogenesis, and that the expression of leptin requires the presence of prolactin.     

Effect of polymorphisms in the leptin, leptin receptor, and acyl-coenzyme A:diacylglycerol acyltransferase 1 (DGAT1) genes and genetic polymorphism of milk proteins on cheese characteristics

Cheese production has increased worldwide during the last decade and is expected to increase within the coming decade as well. Despite this, the relations between cow genetics and cheese characteristics are not fully known. The aim of this study was to determine if polymorphisms in the leptin (LEP), leptin receptor (LEPR), and acyl-coenzyme A:diacylglycerol acyltransferase 1 (DGAT1) genes as well as genetic variants of β-casein (β-CN), κ-CN, and β-lactoglobulin (β-LG) affect technological properties important for cheese production and, hence, could act as genetic makers for cheese quality. Individual milk samples from the Swedish Red and the Swedish Holstein breeds were analyzed for sizes of CN micelles and fat globules as well as rennet-induced gel strength, gelation time, and yield stress. Model cheeses were produced to study yield, hardness, and pH of the cheeses. The A1457G, A252T, A59V, and C963T single nucleotide polymorphisms (SNP) were analyzed on the LEP gene, the T945M SNP on the LEPR gene, and the Nt984+8(A-G) SNP on the DGAT1 gene. In addition, genetic variants of β-CN, κ-CN, and β-LG were determined. The results indicate that technological properties were influenced by the LEPR_T945M polymorphism, which had an association with gel strength, yield stress, and cheese hardness (T > C). However, also LEP_A252T was shown to affect gel strength (T > A), whereas the LEP_A59V had an effect on fat globule size (T > C). For the milk protein genes, favorable effects were found for the A and B variants of β-LG and κ-CN, respectively, on gel strength, gelation time, and yield stress. In addition, the B variant of κ-CN was shown to be associated with smaller CN micelles than the A variant. Thus, the results demonstrate potential genetic markers for cheese characteristics. However, milk composition traits also affected the obtained results, thus making it necessary to thoroughly assess the different aspects regarding the influence of gene effects on cheese characteristics before directly selecting for certain alleles or genetic variants to improve the processing and quality of cheese.     

Leptin concentrations in relation to energy balance,milk yield,intake, live weight,and estrus in dairy cows

The objective of this study was to describe fluctuations in leptin concentrations during late pregnancy and lactation and to investigate how those fluctuations are related to energy balance, milk yield, milk components, dry matter intake, live weight, first postpartum luteal activity, and first observed estrus during lactation. Live weight, dry matter intake, energy balance, and milk yield were measured weekly on 304 primiparous Holstein cows for the first 80 d of lactation. The first postpartum luteal activity was determined by measuring milk progesterone, and independently, first observed estrus. For measuring leptin concentrations from 30 d before until 80 d after calving, blood samples were taken at 2-wk intervals at a fixed time of the day after milking but before feeding. Leptin concentrations were high during pregnancy and declined to a nadir at parturition. It seems that leptin concentrations reflect the state of energy balance during lactation; plasma leptin concentrations were lower in cows with a mean negative energy balance during lactation. Those cows usually produced more milk, consumed less feed, and had a lower live weight compared with cows having a mean positive energy balance. The recovery of leptin concentrations from the leptin nadir at parturition seemed to depend on the extent and duration of the negative energy balance, thus probably on the amount of fat that was re-accumulated. Although there was lack of a relationship between leptin and first postpartum luteal activity, higher leptin concentrations associated with shorter intervals to first observed estrus might indicate a relationship between leptin and expression of estrus.     

Short communication: effect of leptin gene polymorphisms on breeding value for milk production traits

New molecular techniques focused on genome analysis open new possibilities for complex evaluation of economically important traits in farm animals. Milk production traits are typical quantitative characteristics controlled by a number of genes. Mutations in their sequences may alter animal performance as well as their breeding values. In this study, we investigated the effect of 3 restriction fragment length polymorphisms (RFLP): HphI, Kpn2I, and Sau3AI in the leptin gene, on bull breeding values for milk, fat, and protein yield, and fat and protein content. One hundred seventeen Polish Black and White AI bulls were genotyped. Pedigree analysis indicated a relatively close relationship between the bulls. Statistical analysis indicated that the HphI polymorphism has a significant effect on milk and protein yield. Animals with the TT genotype had approximately 2x higher estimated breeding values for milk and protein yields. No effect was found for the other 2 polymorphisms.     

Hot topic: an association between a leptin single nucleotide polymorphism and milk and protein yield

Allelic variation (C to T transition that results in an Arg25Cys) in the leptin gene has been associated with increased fat deposition in beef cattle. We report that this same genetic variant is also present in dairy breeds. Body fat reserves play an important role in sustaining high milk production in early lactation, when energy intake is limited. To test for an association between the leptin single nucleotide polymorphism and milk productivity, we genotyped 416 Holstein cows and compared lactation performance data using a mixed model. Animals homozygous for the T allele produced more milk (1.5 kg/d vs. CC animals) and had higher somatic cell count linear scores, without significantly affecting milk fat or protein percent over the entire lactation. The increase in milk yield is most prominent in the first 100 d of lactation (2.44 kg/d), declining to 1.74 kg/d between 101 and 200 d in lactation. The milk yield advantage, observed in cows homozygous for the T allele, could represent a major economic advantage to dairy producers.     

免疫乳的研究进展

对免疫乳的概念、生物功能、免疫乳的制备及国内外免疫乳的发展及其研究进展作一综述,提出了免疫乳发展过程中存在的问题。     

免疫学检测羊乳中掺入牛乳成分

由于营养、价格和原料等原因，市场上在羊乳中掺入牛乳的现象常有发生。针对这种乳源性掺假陆续产生了多种检测方法，本文主要综述了以ELISA为主的免疫学快速检测方法。     

Effects of milk powders in milk chocolate

The physical characteristics of milk powders used in chocolate can have significant impact on the processing conditions needed to make that chocolate and the physical and organoleptic properties of the finished product. Four milk powders with different particle characteristics (size, shape, density) and "free" milk fat levels (easily extracted with organic solvent) were evaluated for their effect on the processing conditions and characteristics of chocolates in which they were used. Many aspects of chocolate manufacture and storage (tempering conditions, melt rheology, hardness, bloom stability) were dependent on the level of free milk fat in the milk powder. However, particle characteristics of the milk powder also influenced the physical and sensory properties of the final products.     

山羊奶与牛奶和人奶营养成分的比较

对山羊奶、牛奶和人奶中蛋白质、脂肪、维生素、矿物质等主要营养成分进行了比较,分析了3种奶中主要营养成分的差别。通过比较发现,山羊奶在总体营养成分方面优于牛奶,更接近人奶。但山羊奶存在铁、叶酸和维生素B12含量较低以及羊奶膻味的问题,应在营养上对这方面加以重视。