Low Lactose Content Research Articles

Effect of Mycoplasma agalactiae mastitis on milk production and composition in Valle dell Belice dairy sheep

Contagious agalactia (CA), a disease caused by Mycoplasma agalactiae and other pathogenic mycoplasmas, is a well-known multietiological syndrome affecting dairy breeds of sheep and goats in the Mediterranean basin. The aim of this work was to study the effect on milk production and composition of mastitis caused by M. agalactiae in Valle del Belice dairy sheep. All ewes were manually milked twice daily and the milk from both daily milking was analysed for milk composition and somatic cell counts. Moreover the morning milk samples were collected aseptically from each animal for bacteriological analyses. A mixed linear model was utilised to consider milk production and composition between animals infected by CA and healthy animals. After bacteriological investigation using both cultural and molecular methods, 37 ewes were found to be infected by M. agalactiae while 50 uninfected ewes were randomly selected from the same herds to compare milk production and composition between infected and healthy animals. Statistical analyses showed that the infection with M. agalactiae had a significant effect on yield and some milk components. In particular, infected ewes showed lower milk production with lower lactose content and higher somatic cell counts. The implementation of disease control programmes based on rapid laboratory diagnosis and modern control methods is desirable for Mediterranean endemic areas.HighlightsContagious agalactia is caused by M. agalactiae and affects small ruminant dairy farms in the Mediterranean basin.Contagious agalactia is endemic in many countries and has a severe health and economic impact.Effect on milk production and composition of mastitis caused by M. agalactiae.

LAKTOZ İNTOLERANSIN PREVALANSI, TEŞHİSİ VE LAKTOZSUZ BESLENME TAVSİYELERİ

Lactose is a disaccharide found only in milk, and after weaning, the synthesis of lactase, which breaks down lactose, stops or decreases in most individuals. This condition, known as lactose intolerance, results in the inability of the digestion of milk and is very common in the world. Because of the single nucleotide polymorphisms occurring on the lactase gene, the lactase enzyme can be synthesized for life in some individuals. The prevalence of this condition called lactase persistence varies according to ethnic groups. Although there are various methods for the diagnosis of lactose intolerance, observation of symptoms is often sufficient for the diagnosis of the disease. Those who have lactose intolerance should apply a life-long lactose-free diet. Since milk is a rich source of some important nutrients such as calcium, it is important for lactose intolerance patients to meet their needs like calcium from foods with low lactose content such as cheese and yogurt. In this study, information about lactose intolerance was given and lactose intolerance prevalence, diagnosis methods, and lactose-free diet were examined. This study aims to increase the lactose intolerance awareness of both patients and food industry stakeholders.

Development and evaluation of freeze-dried milk powder with low-lactose content

This work aims to develop a freeze-dried milk powder with low lactose content and evaluate the percentage composition, microbiological analysis, and the soy lecithin and temperature effect on the solubility, dispersibility, and wettability of the final product. According to the results, treatments with and without hydrolysis showed significant differences in moisture (3.96% and 2.63%), ash (8.92% and 10.0%), lactose (1.57% and 61.46%), and glucose (33.79% and 0.81%) contents. In both treatments, no microbiological contaminant was observed. For high values of solubility, the most appropriate combination was lecithin 0.6% at 80 ºC, for dispersibility was lecithin 0.6% at 94 ºC, and for wettability was lecithin 0.65% at 90 ºC. Based on the results, freeze-dried milk powder with low lactose content can represent a new technologically and nutritionally viable product. This can be an alternative production process representing potential for marketing as a final product or used as base for the food preparation containing milk with low lactose content.

Influence of milk protein concentrates with modified calcium content on enteral dairy beverage formulations: Physicochemical properties

Because of their high protein and low lactose content, milk protein concentrates (MPC) are typically used in the formulation of ready-to-drink beverages. Calcium-mediated aggregation of proteins during storage is one of the main reasons for loss of storage stability of these beverages. Control and calcium-reduced MPC [20% calcium-reduced (MPC-20) and 30% calcium-reduced (MPC-30)] were used to evaluate the physicochemical properties in this study. This study was conducted in 2 phases. In phase I, 8% protein solutions were prepared by reconstituting the 3 MPC and adjusting the pH to 7. These solutions were divided into 3 equal parts, 0, 0.15, or 0.25% sodium hexametaphosphate (SHMP) was added, and the solutions were homogenized. In phase II, enteral dairy beverage formulations containing MPC and a mixture of gums, maltodextrin, and sugar were evaluated following the same procedure used in phase I. In both phases, heat stability, apparent viscosity, and particle size were compared before and after heat treatment at 140°C for 15 s. In the absence of SHMP, MPC-20 and MPC-30 exhibited the highest heat coagulation time at 30.9 and 32.8 min, respectively, compared with the control (20.9 min). In phase II, without any addition of SHMP, MPC-20 exhibited the highest heat coagulation time of 9.3 min compared with 7.1 min for control and 6.2 min for MPC-30. An increase in apparent viscosity and a decrease in particle size of reconstituted MPC solutions in phases I and II with an increase in SHMP concentration was attributed to casein micelle dissociation caused by calcium chelation. This study highlights the potential for application of calcium-reduced MPC in dairy-based ready-to-drink and enteral nutrition beverage formulations to improve their heat stability.

Physicochemical, Nutritional, and Organoleptic Characterization of a Skimmed Goat Milk Fermented with the Probiotic Strain Lactobacillus plantarum C4.

The benefits of goat milk, fermented milks, and probiotics for the humans are well documented. In this study, a novel fermented goat milk was manufactured with the putative probiotic strain Lactobacillus plantarum C4 together with L. bulgaricus and Streptococcus thermophilus. Ultrafiltration was chosen as the skimmed milk concentration method because it produced the best viscosity and syneresis and a high casein content. The viability rate of all bacterial strains was >107 cfu/mL, even after 5 weeks of storage or after in vitro gastrointestinal digestion, which is especially important for exertion of the probiotic strain functionalities. This fermented milk is also a good source of nutrients, having a low lactose and fat content, high protein proportion, and good mineral concentration. According to these data and the overall acceptability described by panelists, this fermented milk is a healthy dairy product comparable with commercially available fermented milks.

Detection of lactose in products with low lactose content

Quantification of lactose in lactose-free products requires a sensitive method and is often hindered by high levels of glucose and galactose that are present after lactase treatment. The enzymatic method presented here includes an enzymatic glucose depletion step and enables sensitive analysis of low levels of lactose at a detection limit of 25 mg kg−1, with repeatability of 57 mg kg−1 and a recovery rate of 94%. This method was used to measure lactose levels in different cheese types and residual levels of lactose in lactose-free products. Lactose concentrations were below the detection limit in all ripened cheeses, below 0.1% in lactose-free products, and highly variable in fresh cheeses and other products.

Effects of heat stress and dietary zinc source on performance and mammary epithelial integrity of lactating dairy cows

Dietary Zn and heat stress alter gut integrity in monogastric animals. However, effects of Zn on mammary epithelial integrity in heat-stressed lactating dairy cows have not been studied. Multiparous lactating Holstein cows (n = 72) were randomly assigned to 1 of 4 treatments with a 2 × 2 factorial arrangement to study the effects of environment and Zn source on performance and mammary epithelial integrity. Treatments included 2 environments [cooled (CL) or not cooled (NC)] and 2 Zn sources [75 mg/kg of supplemental Zn as Zn hydroxychloride (IOZ) or 35 mg/kg of Zn hydroxychloride + 40 mg/kg of Zn-Met complex (ZMC)]. The experiment was divided into baseline and environmental challenge phases of 84 d each. All cows were cooled during the baseline phase (temperature-humidity index = 72.5), whereas NC cows were not cooled during environmental challenge (temperature-humidity index = 77.7). Mammary biopsies were collected on d 7 and 56 relative to the onset of environmental challenge to analyze gene expression of claudin 1, 4, and 8, zonula occludens 1, 2, and 3, occludin, and E-cadherin and protein expression of occludin and E-cadherin. Deprivation of cooling increased respiration rate (64.8 vs. 73.9 breaths/min) and vaginal temperature (39.03 vs. 39.94°C) and decreased dry matter intake (26.7 vs. 21.6 kg/d). Energy-corrected milk yield decreased for NC cows relative to CL cows (24.5 vs. 34.1 kg/d). An interaction between environment and Zn source occurred for milk fat content as CL cows fed ZMC had lower milk fat percentage than other groups. Relative to CL cows, NC cows had lower concentrations of lactose (4.69 vs. 4.56%) and solids-not-fat (8.46 vs. 8.32%) but a higher concentration of milk urea nitrogen (9.07 vs. 11.02 mg/mL). Compared with IOZ, cows fed ZMC had lower plasma lactose concentration during baseline and tended to have lower plasma lactose concentration during environmental challenge. Plasma lactose concentration tended to increase at 3, 5, and 41 d after the onset of environmental challenge in NC cows relative to CL cows. Treatment had no effect on milk BSA concentration. Cows fed ZMC tended to have higher gene expression of E-cadherin relative to IOZ. Compared with CL, NC cows had increased gene expression of occludin and E-cadherin and tended to have increased claudin 1 and zonula occludens 1 and 2 gene expression in the mammary gland. Protein expression of occludin and E-cadherin was unchanged. In conclusion, removing active cooling impairs lactation performance and affects gene expression of proteins involved in the mammary epithelial barrier, and feeding a portion of dietary zinc as ZMC improves the integrity of the mammary epithelium.

Dynamics of lactose changes during ripening of Edam cheese

The published data show that milk and dairy products are an important part of the diet in the European population and the population of North America, where they cover from 20 to 30% of protein, 15% of lipids and about 80% of calcium from food sources. The exclusion of milk and dairy products from human diet due to lactose intolerance (approximately 75% of the global population are lactose malabsorbers) can cause very serious health consequences. From a public health point of view, it is therefore extremely important for diary products to capture all the facts about the fluctuation process or rather reduction of lactose content during dairy production technology. The aim of our study was to determine the lactose in various stages of Edam cheese ripening, to assess its suitability for consumption on the afflicted population. For the determination of lactose (day of production, first, second and sixth month of storage) the reference enzymatic method using the enzymatic set Megazyme International Ireland with a detection limit of 0.00296 g.100 g-1was applied. This set is intended for determination of lactose in samples presented as low-lactose or lactose-free products and is based on the hydrolysis of lactose to D-galactose and D-glucose by the enzyme β-galactosidase. After the subsequent oxidation of galactose, the amount of formed NADH (stoichiometrically related to the amount of lactose contained in the sample) is measured in a spectrophotometer at 340 nm. According to current legislation, the lactose-free product must contain less than 10 mg of lactose per 100 g or 100 mL of the consumed product, while a product that contains up to 1 g of lactose in 100 g or 100 mL of the product consumed is considered as a product with low lactose content. The study results showed that even after one month of storage Edam cheese can be, according to current national and EU legislation, designated as a lactose-free food. This means that the consumer receives a lactose-free product whenever buying this type of cheese.

The impact of membrane pretreatment on the enzymatic production of whey‐derived galacto‐oligosaccharides

AbstractThis study presents a multistep process for the valorization of whey that involves membrane filtration techniques to fractionate whey compounds and the subsequent enzymatic conversion of lactose into galacto‐oligosaccharides with a degree of polymerization (DP) of 3–5. Partially demineralized whey was first concentrated and diafiltered by ultrafiltration (UF) to obtain whey protein isolates. Over 97% of the initial amount of lactose was recovered into the permeate which was then concentrated by nanofiltration (NF) up to 330 g L−1. Finally, a systematic study was performed to investigate the hydrolytic and transgalactosylation activity of Biolacta N5, a Bacillus circulans‐derived β‐galactosidase, on whey‐derived substrates consisting of lactose in various concentrations. Hydrolysis was especially pronounced for UF permeates with low lactose concentrations (< 50 g L−1), whereas transgalactosylation was dominant for streams concentrated by NF, obtaining comparable yields of the DP3‐5 fractions (∼ 35%) for moderate and high NF concentration factors.Practical applicationsThe market for functional foods and dairy‐based functional beverages represents a growing segment of the global food industry. This article describes a technique for the valorization of whey that is based on the fractionation of whey constituents and the subsequent bioconversion of lactose into GOS. GOS are prebiotic substances with favorable technological properties such as low viscosity and good pH and temperature stability. These low‐calorie sweeteners can be added to a wide range of foods to increase product functionality. The here proposed multiproduct process has potential applications in whey management practice. The reported experimental data on the performance of the processing steps and the proposed approaches to the synchronization of the individual operations is useful for the design of whey valorization processes with reduced waste and energy consumption.

Effect of ‘in situ’ produced bacteriocin thermophilin T on the microbiological and physicochemical characteristics of Myzithra whey cheese

Myzithra whey cheese was made by the addition of ovine milk (10%) to whey, previously fermented by the bacteriocinogenic strain Streptococcus thermophilus ACA‐DC 0040, resulting in production of a bacteriocin (thermophilin T) titre at a concentration 40 960 ± 2560 AU/mL. The final antimicrobial activity in the ready‐to‐eat cheese was sufficient to inhibit the growth of coliforms and restrict the growth of bacteria of the Micrococcus group, thus contributing to and increased shelf life and the safety of cheese. A lower lactose content was observed in the cheese, which would lead to better acceptance by lactase‐deficient consumers. Moreover, the sensory characteristics of the cheese remained unchanged during the whole cold storage period, ensuring an extended shelf life.

Development of functional fermented whey–oat-based product using probiotic bacteria

The aim of the present study was to formulate a fermented whey product using probiotic bacteria and whey protein concentrate (WPC containing 70% of proteins) to obtain a fermented product with low lactose and β-lactoglobulin (BLG) content. Several factors such as starter culture concentration (1, 5, and 10%) and fermentation time (2, 4, 6, 8, and 10h) were optimized on the basis of growth activity in terms of viable count, pH, and acidity. Starter culture concentration and fermentation time of 5% and 10h, respectively, show the optimal viable count (9.8×1010) and pH (4.42) as per the requirement. Proteolysis of WPC by a mixed culture of Lactobacillus acidophilus and Lactobacillus bulgaricus was found to be 98.8μg/ml. Hydrolysis of whey proteins by probiotic bacteria was detected by SDS-PAGE. A significant (p≤0.05) decrease in cell viability and pH was observed as the refrigerated storage period goes on increasing (0-15days).

Selective and sensitive determination of lactose in low-lactose dairy products with HPAEC-PAD.

The demand for low lactose dairy products is increasing and more different lactose free food is commercially available. The level of lactose in these products decreased during the last years and nowadays a concentration of <0.01% is generally accepted as "lactose free". For the determination of the lactose concentrations in these dairy products a sensitive analysis method is needed. We developed a method for the determination of low concentrations of lactose in a wide range of dairy products. A simple sample preparation with dilution, centrifugation and ultrafiltration is efficient for the isolation of lactose from the sample matrix. In this paper, a new HPAEC-PAD analysis on a CarboPac PA100 column gives a good separation of lactose from the other saccharides. This separation in combination with the PAD detector yields a selective and sensitive method for the quantification at the desired concentrations of lactose in low lactose dairy products.

Optimization of recombinant β-NGF expression in Escherichia coli using response surface methodology

ABSTRACTHuman nerve growth factor a member of the neurotrophin family can be used to treat neurodegenerative diseases. As it has disulfide bonds in its structure, periplasmic expression of it using appropriate signal sequence is beneficial. Therefore, in this work β-nerve growth factor (β-NGF) was expressed in Escherichia coli using pET39b expression vector containing DsbA signal sequence. In an initial step, the effect of isopropyl β-D-1-thiogalactopyranoside (IPTG) and lactose concentration as inducer on protein production was investigated using response surface methodology. Then the effect of different postinduction time and temperature on protein production was studied. Our results indicated that the highest β-NGF production was achieved with 1 mM IPTG and low concentrations of lactose (0–2% w/v), low cultivation temperature of 25°C and postinduction time of 2 hr. Also following β-NGF purification, bioassay test using PC12 cell line was done. The biological activity of the purified β-NGF showed a similar cell proliferation activity with the standard recombinant human β-NGF. In conclusion, the results indicated an optimized upstream process to obtain high yields of biologically active β-NGF.

Compositional profile of ovine milk with a high somatic cell count: A metabolomics approach

Ovine milk (Sarda breed) with high somatic cell count (SCC) (>1 × 106 cell mL−1) was compared with similar milk of low SCC (<150 × 103 cell mL−1) using a metabolomics approach, whereby the metabolite profile of milk was studied by gas chromatography coupled to mass spectrometry. Discriminant analysis indicated that high SCC milk samples have metabolite profiles from those of low SCC samples. Malic acid, ribitol, glucose and medium-short chain fatty acids were up-regulated in milk with high SCC, while stearic acid, oleic acid, scyllo-inositol, glutamine, threonine, and glycine were down-regulated. These differences may be related to metabolite release by somatic cells, inflammation status, altered permeability of the udder tight junctions, and changes in milk osmotic equilibrium. Moreover, high SCC milk samples showed higher levels of proteins, casein and fat, lower concentrations of lactose and urea, and a different fatty acid profile from that of low SCC milk.

Multivariate analysis of lactose content in milk of Holstein and Jersey cows1

This study evaluated the factors influencing the variation in the lactose content of milk in Holstein and Jersey herds in Santa Catarina, southern Brazil, using multivariate analysis. Data from 73 dairy herds in the Dairy Herds Improvement Program of the State of Santa Catarina were provided by the Santa Catarina Association of Cattle Breeders (ACCB). A total of 46,242 monthly records of Holstein and Jersey (59 and 41 % of the total records, respectively) cows from 2009 to 2012 were analyzed using multiple correspondence, factor, and cluster analyses. Lactose content was observed to correlate with somatic cell count and parity, whereas the evaluated breeds, as well as the production and concentrations of fat and protein in the milk, were not associated with the lactose content. The cows were categorized into three groups, the first consisting of cows of both breeds with low lactose content (4.19), high somatic cell score (5.82), and higher parity (2.50), contrasting with two other groups each with mean values characteristic for Holstein and Jersey breeds, respectively. Analysis of cows without subclinical mastitis ( &amp;lt; 200,000 somatic cells ml-1) revealed that the relationship of parity with lactose level was independent of the effect of somatic cells. Lactose contents less than 4.4 % were observed in autumn. Overall, the present study suggests that the lactose content of milk is influenced by somatic cell count and parity and that it varies seasonally; however, it is not related to breed, milk yield, milk fat content, or milk protein level.

DETERMINAÇÃO DO TEOR DE SÓDIO E LACTOSE EM QUEIJOS MUSSARELA E COLONIAL CONSUMIDOS NA REGIÃO SUDOESTE DO PARANÁ

Pesquisas têm indicado que os queijos brasileiros têm consumido elevado teor de sal, o que pode ser visto como um problema de saúde pública, devido ao grande consumo desses produtos pela população. Além disso, poucos estudos têm avaliado o teor de lactose em queijos. Por outro lado, o lançamento no mercado de novos produtos isentos de lactose é grande. Queijos comumente apresentam baixo conteúdo de lactose, dessa forma, para alguns tipos de queijos, justifica-se o desenvolvimento de linhas de produtos com baixo teor ou isentos de lactose, mas isso não é válido para todas as variedades de queijos, como se têm observado. O objetivo deste trabalho foi determinar os teores de lactose e sódio nos principais tipos de queijos consumidos na região Sudoeste do Paraná, como os queijos mussarela e colonial. Foram coletadas amostras de três marcas de cada tipo de queijo e realizadas análises do teor de lactose, cloreto de sódio, pH e acidez. Os resultados demonstram que os teores de sódio dos queijos analisados são elevados, o que pode trazer prejuízos à saúde dos consumidores. Pode-se observar também que há grande variação entre as diferentes marcas de queijos quanto ao teor de sódio. A média do teor de lactose foi maior para os queijos mussarela quando comparada aos queijos coloniais. Os queijos apresentaram baixo teor de lactose e, portanto, podem ser consumidos pela grande maioria das pessoas intolerantes à lactose. Além disso, para esses tipos de queijo, não é necessário o desenvolvimento de linhas de produtos “zero lactose”.

HIDRÓLISE DA LACTOSE E PRODUÇÃO DE LEITE EM PÓ: ASPECTOS TECNOLÓGICOS

A indústria de alimentos tem como desafio e oportunidade desenvolver novos produtos com reduzido ou baixo teor de lactose, a fim de atender uma crescente massa de portadores de má digestão da lactose. A secagem dos produtos com lactose hidrolisada é um desafio tecnológico devido a higroscopicidade dos mesmos, influenciando na produtividade, no entupimento das câmaras e na conservação dos pós. O objetivo deste estudo foi avaliar o efeito de diferentes níveis de hidrólise enzimática da lactose (0%, 25%, 50%, 75% e &gt; 99%), na produção e estocagem de leite em pó integral utilizando como ferramentas de caracterização dos produtos fabricados em planta piloto a análise de composição, o controle do grau de hidrólise e as isotermas de sorção. Todos os resultados indicam que a hidrólise da lactose afeta a produção do leite em pó por aumentar a adesão no spray dryer e a absorção de umidade durante a estocagem.

A multifunctional thermophilic glycoside hydrolase from Caldicellulosiruptor owensensis with potential applications in production of biofuels and biochemicals.

BackgroundThermophilic enzymes have attracted much attention for their advantages of high reaction velocity, exceptional thermostability, and decreased risk of contamination. Exploring efficient thermophilic glycoside hydrolases will accelerate the industrialization of biofuels and biochemicals.ResultsA multifunctional glycoside hydrolase (GH) CoGH1A, belonging to GH1 family with high activities of β-d-glucosidase, exoglucanase, β-d-xylosidase, β-d-galactosidase, and transgalactosylation, was cloned and expressed from the extremely thermophilic bacterium Caldicellulosiruptor owensensis. The enzyme exerts excellent thermostability by retaining 100 % activity after 12-h incubation at 75 °C. The catalytic coefficients (kcat/Km) of the enzyme against pNP-β-D-galactopyranoside, pNP-β-D-glucopyranoside, pNP-β-D-cellobioside, pNP-β-D-xylopyranoside, and cellobiose were, respectively, 7450.0, 2467.5, 1085.4, 90.9, and 137.3 mM−1 s−1. When CoGH1A was supplemented at the dosage of 20 Ucellobiose g−1 biomass for hydrolysis of the pretreated corn stover, comparing with the control, the glucose and xylose yields were, respectively, increased 37.9 and 42.1 %, indicating that the enzyme contributed not only for glucose but also for xylose release. The efficiencies of lactose decomposition and synthesis of galactooligosaccharides (GalOS) by CoGH1A were investigated at low (40 g L−1) and high (500 g L−1) initial lactose concentrations. At low lactose concentration, the time for decomposition of 83 % lactose was 10 min, which is much shorter than the reported 2–10 h for reaching such a decomposition rate. At high lactose concentration, after 50-min catalysis, the GalOS concentration reached 221 g L−1 with a productivity of 265.2 g L−1 h−1. This productivity is at least 12-fold higher than those reported in literature.ConclusionsThe multifunctional glycoside hydrolase CoGH1A has high capabilities in saccharification of lignocellulosic biomass, decomposition of lactose, and synthesis of galactooligosaccharides. It is a promising enzyme to be used for bioconversion of carbohydrates in industrial scale. In addition, the results of this study indicate that the extremely thermophilic bacteria are potential resources for screening highly efficient glycoside hydrolases for the production of biofuels and biochemicals.

The composition and properties of jenny milk

Jenny breeding and the production of jenny milk are becoming more common, especially on family farms in the area of Istria and Dalmatia, but in continental Croatia as well. The aim of this study was to explore basic chemical and fatty acid composition, somatic cell count and sensory traits of jenny milk. In total eleven milk samples were analized from two breeds: Littoral-Dinaric (Dalmatian) jennies (N=6) and Istrian jennies (N=5) originating from farms in the area of Zagreb and Istrian County. Fat content was markedly low and was 1.16 % at the most, whereas the average fat content in the milk of Istrian jennies was 0.14 %, i.e. 0.69 % in Dalmatian jennies. The average protein content was 1.29 % and average lactose content 6.5 %. The milk of Dalmatian jennies contained 3.8 log10 mL-1 of somatic cells whose values were lower in the milk of Istrian jennies (3.2 log10 mL-1). At the same time a higher total count of white blood cells (4.9-5.3 x 109/L) was determined in milk samples of Istrian jennies, in comparison to the milk of Dalmatian jennies (5.1 x 109/ L at the most). The fatty acid composition showed that the content of saturated fatty acids (SFA) in the milk of Istrian jennies was 70.45 %, while in the milk of Dalmatian jennies it was 59.92 %. The monounsaturated fatty acids (MUFA) were represented on average with 21.23 % and 24.61 %, while polyunsaturated fatty acids (PUFA) with 8.31 % and 15.46 % in Istrian and Dalmatian jennies. The total ratio saturated/unsaturated fatty acids ranged from 0.37 to 0.72 at the most and it was lower in milk samples of Istrian jennies. Jenny milk is characterized by a low fat content and high lactose content, and fatty acid composition with a favourable ratio of saturated and unsaturated fatty acids. The somatic cell count in the milk is lower in comparison to the milk of other domestic animals.

Characterization of airag collected in Ulaanbaatar, Mongolia with emphasis on isolated lactic acid bacteria.

BackgroundAirag, alcoholic sour-tasting beverage, has been traditionally prepared by Mongolian nomads who naturally ferment fresh mares’ milk. Biochemical and microbiological compositions of airag samples collected in Ulaanbaatar, Mongolia and physiological characteristics of isolated lactic acid bacteria were investigated.MethodsProtein composition and biochemical composition were determined using sodium dodecyl sulfate-gel electrophoresis and high performance liquid chromatography, respectively. Lactic acid bacteria were identified based on nucleotide sequence of 16S rRNA gene. Carbohydrate fermentation, acid survival, bile resistance and acid production in skim milk culture were determined.ResultsEquine whey proteins were present in airag samples more than caseins. The airag samples contained 0.10–3.36 % lactose, 1.44–2.33 % ethyl alcohol, 1.08–1.62 % lactic acid and 0.12–0.22 % acetic acid. Lactobacillus (L.) helveticus were major lactic acid bacteria consisting of 9 isolates among total 18 isolates of lactic acid bacteria. L. helveticus survived strongly in PBS, pH 3.0 but did not grow in MRS broth containing 0.1 % oxgall. A couple of L. helveticus isolates lowered pH of skim milk culture to less than 4.0 and produced acid up to more than 1.0 %.ConclusionHighly variable biochemical compositions of the airag samples indicated inconsistent quality due to natural fermentation. Airag with low lactose content should be favorable for nutrition, considering that mares’ milk with high lactose content has strong laxative effect. The isolates of L. helveticus which produced acid actively in skim milk culture might have a major role in production of airag.