Selenium content of milk and milk products of Turkey. II

Selenium content of 1028 milk and milk products of Turkey are presented in this study. The selenium content of human milk (colostrum, transitional, and mature milk), various kinds of milk [cow, sheep, goat, buffalo, paper boxes (3%, 1.5%, 0.012% fat), bottled milk, condensed milk (10% fat), mineral added milk (1.6%), and banana, strawberry, and chocolate milk] and milk products (kefir, yogurt, Ayran, various cheese, coffee cream, ice cream, butter, margarine, milk powder, and fruit yogurt) in Turkey were determined by a spectrofluorometric method. The selenium levels of cow milks collected from 57 cities in Turkey were also determined. Selenium levels in cow milk varied with geographical location in Turkey and were found to be lowest for Van and highest for Aksaray. The results [milk (cow, sheep, goat, buffalo and human) and milks products] were compared with literature data from different countries.     

Applications of biotechnology and genomics in goats

Goat breeding has many advantages, including economic (low cost); sociological (products made from skin and other elements), and ecological (goat adaptability). Products such as goat kid meat (cabrito), which is considered a delicacy, and goat milk cheese are some of the most appreciated. Many high priced products such as purses, shoes, jackets, and other articles are made from the fur and skin of goats. Presently, by applying new biotechnology research to the goat industry, their productivity, molecular diagnosis, health, and genetic diversity can be improved. Surely there are many more opportunities to come for modern biotechnology. Discussing these with audiences, such as those attending specialized international conferences on goat production, are of great importance because there is a lack of knowledge among goat breeders and resistance for carrying out this type of research. Events of this type should be of great use for instructing attendants, publicizing the usefulness of goat production, and creating steps towards discovering available benefits and promises of modern biotechnology.     

Recent advances in exploiting goat's milk: Quality,safety and production aspects

Goat milk production is a dynamic and growing industry that is fundamental to the wellbeing of hundreds of millions of people worldwide and is an important part of the economy in many countries. The aim of the present review is to provide an integrated and critical analysis of the major aspects in this field to highlight unexploited nutritional potential of goat milk and the need for improvements, particularly in food safety. First, it should be kept in mind that goat milk like cow milk delivers many nutrients with relatively low energy content, and is relevant to the health of consumers throughout the life cycle. In addition, the review presents data suggesting that goat milk possesses many advantages over cow milk, for use as a nutritional source for infants and children and as a medicinal food. Furthermore, goats, by consuming large amounts of natural browsing plants all year around, are a potentially overlooked “treasure trove”, with respect to health promoting components. The survey suggests that total bacterial count that is currently used as the major quality measure to prevent pathogen-related food toxicity is not sufficiently effective. The proposal is to include somatic cell count as a routine criterion to qualify the hygienic status of goat milk in terms of the relevant physiology and biochemistry. The paper presents a novel mechanism controlling milk secretion, and demonstrates the use of this knowledge in making decisions for two major managerial tasks that farmers face, namely milking frequency that dictates to a large extent the milk yield and workload on the farm, and helping to deal with subclinical mastitis that is the single major cause for economical losses in dairy farms worldwide.     

Influence of breed and husbandry on viscosity of Israeli goat milk yogurt

Goat’s milk yogurt prepared from milk of different goat breeds on different farm types resulted in different viscosity. Yogurt from milk of goat breeds browsing on pasture was richer in solids and resulted in significantly higher viscosity compared with that of cow milk yogurt and yogurt produced from milk of goats fed hay and concentrate indoors. Milk from goats browsing on pasture was diluted in total solids content close to that of milk from goats kept indoors and cows. Yogurt made from this diluted milk still resulted in higher viscosity. It appears that milk from goat breeds browsing on pastures contains certain factor(s) that causes an increase in the viscosity of yogurt produced from it.     

Purification and characterization of milk clotting enzyme from goat (Capra hircus)

Chymosin, the major component of rennet (milk clotting enzyme), is an acid protease produced in the fourth stomach of milk-fed ruminants including goat and sheep in the form of an inactive precursor prochymosin. It is responsible for hydrolysis of kappa-casein chain in casein micelles of milk and therefore, used as milk coagulant in cheese preparation. The present investigation was undertaken to purify and characterize goat (Capra hircus) chymosin for its suitability as milk coagulant. The enzyme was extracted from abomasal tissue of kid and purified nearly 30-fold using anion exchanger and gel filtration chromatography. Goat chymosin resolved into three major active peaks, indicating possible heterogeneity when passed through DEAE-cellulose ion exchange column. The purified enzyme had a molecular mass of 36 kDa on SDS-PAGE, which was further confirmed by Western blot analysis. The purified enzyme preparation was stable up to 55 degrees C with maximum activity at 30 degrees C. The milk clotting activity was decreased steadily as pH is increased and indicated maximum activity at pH 5.5. Proteolytic activity of goat chymosin increased with incubation time at 37 degrees C. Goat chymosin was found to be more thermostable than cattle chymosin and equally stable to buffalo chymosin.     

Predictive formulae for goat cheese yield based on milk composition

Prediction of the yield and quality of different types of cheeses that could be produced from a given type and/or amount of goat milk is of great economic benefit to goat milk producers and goat cheese manufacturers. Bulk tank goat milk was used for manufacturing hard, semi-hard and soft cheeses (N = 25, 25 and 24, respectively) to develop predictive formulae of cheese yield based on milk composition. Fat, total solids, total protein and casein contents in milk and moisture-adjusted cheese yield were determined to establish relationships between milk composition and cheese yield. Soft, semi-hard and hard cheeses in this study had moisture contents of 66, 46 and 38%, respectively, which could be used as reference standards. In soft cheese, individual components of goat milk or a combination of two or three components predicted cheese yield with a reasonably high correlation coefficient (R² = 0.73–0.81). However, correlation coefficients of predictions were lower for both semi-hard and hard cheeses. Overall, total solids of goat milk was the strongest indicator of yield in all three types of cheeses, followed by fat and total protein, while casein was not a good predictor for both semi-hard and hard cheeses. When compared with moisture-adjusted cheese yield, there was no difference (P > 0.05) in predicting yield of semi-hard and hard goat milk cheeses between the developed yield formulae in this study and a standard formula (the Van Slyke formula) commonly used for cow cheese. Future research will include further validation of the yield predictive formulae for hard and semi-hard cheeses of goat milk using larger data sets over several lactations, because of variation in relationships between milk components due to breed, stage of lactation, season, feeding regime, somatic cell count and differences in casein variants.     

Co-construction of a method for evaluating the intrinsic quality of bovine milk in relation to its fate

There are time-tested assessments for the environmental and economic aspects of sustainability. Its societal aspect has mainly been approached through the assessment of animal welfare. However, the intrinsic quality of milk is seldom taken into account. We developed a participatory construction method for the overall assessment of intrinsic milk quality in its different dimensions (sensory, technological, nutritional and health), according to the fate of the raw milk. Two assessment models were developed, for semi-skimmed standardized ultra-high temperature (UHT) milk and for pressed uncooked non-standardized raw milk cheese. They were constructed by a participatory approach involving experts in the dairy sector with the aim to obtain a diagnostic tool that could be used in the field to help farmers to manage the quality of their milk (by prioritizing improvements on major problems). They were shaped from prerequisite specifications (limited costs and time of application, desire to obtain a transparent tool with all the steps kept visible) and current technical and scientific knowledge. They were based on indicators obtained from raw bulk tank milk analyses (30 for UHT milk and 50 for cheese assessments), which were then aggregated into criteria, principles, dimensions and overall intrinsic quality at farm level. The assessment models had parts in common, for example, same four dimensions, common indicators for health and nutritional dimensions. They also had process-specific features: units chosen, criteria, indicators and weightings in relation to the final product specifications. For instance, sensory and technological dimensions are more complex and preponderant in the cheese assessment (three principles for cheese vs one for UHT milk in both dimensions). Another example is the lack of microbial pathogens (as potential health risk for consumer) in the UHT milk assessment because of pasteurization. The assessment models then underwent a sensitivity analysis and an application in 30 farms in indoor and grazing periods to finally obtain overall UHT milk and cheese quality scores at a 1-year level. The tool was found to be applicable at farm level. However, we observed low overall quality scores with a narrow dispersion, characteristic of a severe evaluation. Even so, the assessment models showed up seasonal differences of the UHT milk and cheese quality at both overall and dimensional levels. In the light of new scientific knowledge and future quality objectives, these are adaptable to other dairy products allowing for their specific features.     

Nutritional value of milk and meat products derived from cloning

The development and use of milk and meat products derived from cloning depends on their safety and on the nutritional advantages they can confer to the products as perceived by consumers. The development of such products thus implies (i) to demonstrate their safety and security, (ii) to show that their nutritional value is equivalent to the traditional products, and (iii) to identify the conditions under which cloning could allow additional nutritional and health benefit in comparison to traditional products for the consumers. Both milk and meat products are a source of high quality protein as determined from their protein content and essential amino acid profile. Milk is a source of calcium, phosphorus, zinc, magnesium and vitamin B2 and B12. Meat is a source of iron, zinc and vitamin B12. An important issue regarding the nutritional quality of meat and milk is the level and quality of fat which usually present a high content in saturated fat and some modification of the fat fraction could improve the nutritional quality of the products. The role of the dietary proteins as potential allergens has to be taken into account and an important aspect regarding this question is to evaluate whether the cloning does not produce the appearance of novel allergenic structures. The presence of bio-activities associated to specific components of milk (lactoferrin, immunoglobulins, growth factors, anti-microbial components) also represents a promising development. Preliminary results obtained in rats fed cow's milk or meat-based diets prepared from control animals or from animals derived from cloning did not show any difference between control and cloning-derived products.     

Organic goat production,processing and marketing: Opportunities,challenges and outlook

Organic goat production can be a rewarding livelihood and is gaining popularity. Global organic production has increased significantly annually over the past decade. Industry analysts forecast that demand in many markets will continue to grow at 10–30% per year, with the international organic market expected to grow to a volume of US$ 100 billion in the next decade. Organic dairy has shown stronger growth rates than organic meat production. In certain regions, the rise in organic milk production has increased the range of processed value-added organic milk and dairy products, and demand is out-stripping supply. The basic principles of organic goat production include care, ecology, fairness, and health as stated by the International Federation of Organic Agriculture Movement (IFOAM). Organic goat production can improve animal welfare, protect the environment, and sustain rewarding rural live styles. There are challenges when dealing with organic goat production, especially when one hopes to control intestinal parasites and to achieve adequate nutritional management. Exploring nutritional technology and disease prevention and treatment will eventually improve the production efficiency. There are various regulations in different countries that apply to certify organic foods, and the number of regulations is growing. One of the leading federations in international organic farming is IFOAM. The standards can be certified under IFOAM then can be recognized in many counties around the world. These regulations serve as branding effort, not only to protect the “organic” brand but also to promote it. Future of organic goat production will have to rely on continue search for alternatives in nutrition and disease prevention and control that are environmentally friendly, human health conscientious and animal considerate. Understanding organic goat farming from economic, ecological, and animal welfare perspectives will increase the likelihood of success.     

Cryopreservation of goat spermatozoa: comparison of two freezing extenders based on post-thaw sperm quality and fertility rates after artificial insemination

TRIS-glucose or skim milk extenders are most commonly used for cryopreserving goat sperm. The aim of this study was to compare the ability of two extenders based on TRIS and skimmed milk buffer to maintain sperm viability after cryopreservation. Goat semen samples (n=110) were frozen with TRIS and with milk extender and thaw. Sperm motion parameters, morphology and acrosomal integrity were assessed in fresh and frozen-thawed samples by Sperm Class Analyzer (SCA) and Diff-Quik and Spermac staining techniques. Pregnancy rates were obtained after cervical insemination with frozen semen doses. The cryopreservation process had a significant effect on acrosome and kinematic parameters. TRIS extender provided more effective preservation of total motility, velocity parameters and amplitude of lateral head displacement after freezing. The percentage of acrosome intact spermatozoa was significantly higher in samples diluted with milk extender. In the insemination doses, mean values of velocity parameters and lateral head displacement were higher in doses processed in TRIS. Spermatozoa frozen in milk extender was mathematically greater than for those frozen with TRIS extenders, though no significant difference exists. We conclude that post-thaw kinematic parameters and acrosome integrity assessed after 1h of incubation was acceptable in both extenders which indicated the feasibility of cryopreserving goat spermatozoa. TRIS extender results in better in vitro performance compared to milk, though these improvements were not reflected in fertility results. Semen doses cryopreserved in milk extender provided greater pregnancy rates after intra-cervical insemination compared to those in TRIS extender (52.4% versus 42.9%).     

Major proteins in goat milk: an updated overview on genetic variability

Milk and dairy products are very important in Mediterranean diet because of their health promoting and organoleptic properties. In many developing countries, goat rearing has a key role in livestock production. What makes goats so popular is their ability to provide high quality food under diverse climatic conditions and resilience to extreme and capricious environments. In the last years, the interest concerning caprine milk has been increasing also to find a new exploitation for local breeds. To promote the goat dairy products there is a clear need to know the quality and the technological aspects of milk produced. That being so, the purpose of this study was to review the available literature on the major goat milk proteins with a particular attention to recent findings on their genetic variability. Moreover, the main effects of different protein variants on milk yield and composition were also discussed.     

An analysis of the volatile flavour compounds in a soft raw goat milk cheese

The major components of the musty cow rind cheeses were identified in a soft raw goat milk cheese as heptan-2-one, nonan-2-one, their corresponding secondary alcohols, some esters and sulfur compounds. Their production was associated with the manufacturing process and its influence on the microbial activity. However a specificity in goat cheese compounds was displayed concerning in particular limonene and some ketones, alcohols and aldehydes.     

Sheep's and goat's dairy products in Italy: Technological,chemical, microbiological,and sensory aspects

Dairy sheep and goat breeding in Europe is most common around the Mediterranean basin, particularly in France, Greece, Italy, and Spain. The milk of sheep and goat is mainly reserved for cheese making that is usually conducted at farm level or in small local dairies. A large part of the production, principally for sheep milk cheese, is protected by the European Community (EC) regulations: the Protected Designation of Origin (PDO) and the Protected Geographic Indication (PGI). These designations constitute an element for the protection of the biodiversity, i.e. territory, animals, microbes, practices, and production systems. Microbiological features and diversity of sheep and goats milk compared to the cow's milk, give peculiar attributes to the cheeses. In several cases, rennet paste, produced from the abomasa of the suckling lambs or kids is used, strongly influencing chemical and sensory characteristics of the cheeses. In this review the technological, microbiological, chemical, and sensory aspects of the PDO and PGI Italian sheep and goat dairy products are reported.     

Available lysine content in human milk: stability during manipulation prior to ingestion

Available lysine content is an indicator of protein quality and nutritional value of milk. Many studies have examined the effects of extraction, treatment and storage of human milk upon its components, though no references are found regarding the possible changes in milk quality as defined by its content in essential amino acids such as lysine. The present study investigates the available lysine content in human milk and the variations in lysine resulting from milk manipulation as follows: (a) Cold storage (refrigeration at 4 degrees C for 48 hours, and frozen for 15 days at -20 degrees C); (b) Thermal treatment under conditions of low (Holder)(63 degrees C/30 minutes) and high pasteurization (75 degrees C/15 seconds). The results obtained show a decrease in milk lysine concentration after storage in both refrigerated and frozen samples. Pasteurization causes a highly significant loss of available lysine. The lysine losses were greater on applying low pasteurization versus the more gentle conditions of high pasteurization. CONCLUSIONS: While manipulation through cold storage or thermal treatment does not affect the protein content of human milk, its protein quality is modified. When human milk must be subjected to hygienization, it is preferable to apply high temperature treatment (75 degrees C, 15 seconds) than habitual pasteurization (63 degrees C, 30 minutes).     

Acid adaptation of Listeria monocytogenes can enhance survival in acidic foods and during milk fermentation.

We have previously shown that tolerance to severe acid stress (pH 3.5) can be induced in Listeria monocytogenes following a 1-h adaptation to mild acid (pH 5.5), a phenomenon termed the acid tolerance response (ATR) (B. O'Driscoll, C. G. M. Gahan, and C. Hill, Appl. Environ. Microbiol. 62:1693-1698, 1966). In an attempt to determine the industrial significance of the ATR, we have examined the survival of adapted and nonadapted cells in a variety of acidic foods. Acid adaptation enhanced the survival of L. monocytogenes in acidified dairy products, including cottage cheese, yogurt, and whole-fat cheddar cheese. Acid-adapted L. monocytogenes cultures also demonstrated increased survival during active milk fermentation by a lactic acid culture. Similarly, acid-adapted cells showed greatly improved survival in low-pH foods (orange juice and salad dressing) containing acids other than lactic acid. However, in foods with a marginally higher pH, such as mozzarella cheese, a commercial cottage cheese, or low-fat cheddar cheese, acid adaptation did not appear to enhance survival. We have previously isolated mutants of L. monocytogenes that are constitutively acid tolerant in the absence of an induction step (O'Driscoll et al., Appl. Environ. Microbiol. 62:1693-1698, 1996). In the present study, one such mutant, ATM56, demonstrated an increased ability to survive in low-pH foods and during milk fermentation when compared with the wild-type strain. Significant numbers of ATM56 could be recovered even after 70 days in both whole-fat and low-fat cheddar cheese. Collectively, the data suggest that ATR mechanisms, whether constitutive or induced, can greatly influence the survival of L. monocytogenes in low-pH food environments.     

Characteristics of goat milk collected from small and medium enterprises in Greece,Portugal and France

Characteristics of goat milk collected from seven small and medium enterprises (SMEs) in Greece, France and Portugal were compared. Results of microbiological, biochemical and technological characteristics (whey draining capacity after lactic or rennet coagulation, acidification aspects, and heat stability) of goat milk with identical and standardised techniques are discussed in relation to effects on technological processes and quality of final products. Results revealed variability of goat milk characteristics collected from the different European areas. Hygienically, goat milk production conditions in Greece and Portugal, under extensive breeding systems were: total bacteria—3.6×10⁷ and 4×10⁷ CFU/ml; coliforms—1.8×10⁶ and 2.5×10⁶ CFU/ml; staphylococci coagulase+—1.7×10⁵ and 7.6×10⁴ CFU/ml, respectively. For France, using intensive breeding systems, microbiological quality was: total bacteria—1.08×10⁵ CFU/ml; coliforms—1.40×10² CFU/ml; staphylococci coagulase+—2.75×10² CFU/ml. Goat milk from Greek farms had the highest fat and protein contents: 51.4 and 37.0 g/kg, compared to goat milk in France: 36.5 and 32.5 g/kg, respectively. Portuguese goat milk was intermediate: 42.7 and 34.9 g/kg, respectively.Regarding technological aspects, Greek and Portuguese milks showed poor whey draining capacity and Greek milks presented low heat stability (100.5 °C on average) but a good propensity to acidify. Systems of production of goat milk, ways of transport of raw goat milk, and the procedures applied inside factories regarding receiving and storage of the raw goat milk are discussed and should be useful for the definition of technological adaptations, that are necessary for best milk and product quality.     

Microbiological characteristics of anevato: a traditional greek cheese

Nine batches of Anevato, raw goat milk cheese, were examined throughout a 60 day storage time at three different periods within the lactation season of the goat. High mean log counts per gram of cheese for aerobic bacteria (7·92–9·56), lactic acid bacteria (7·78–9·32), Gram-negative organisms 5·64–9·67), psychrotrophs (7·90–11·79) and proteolytic bacteria (7·57–9·36) were found. Enterobacteriaceae, coliforms and yeasts were considerably lower. Enterobacteriaceae and coliforms in the curd of cheese made in May were lower by approximately 3·0 log₁₀ cfu g⁻¹ than counts in curd made in January, and were lower by about 2·5 log₁₀ cfu g⁻¹ than those in cheese made in March. This coincided with lower pH and higher counts of lactic acid bacteria in cheese made in March and May. Yeast populations were affected by the season and were higher in May than March and/or January. Lactococci dominated in the cheese until 15 days, but lactobacilli became predominant after 30 days. Lactococcus lactis was the most abundant species of lactic acid bacteria found in Anevato cheese. Results suggest the need for improving milk quality and/or using heat-treated milk to produce Anevato cheese; the use of L. lactis as a starter would possibly eliminate or suppress the growth of undesirable organisms.     

Manufacturing of fermented goat milk with a mixed starter culture of Bifidobacterium animalis and Lactobacillus acidophilus in a controlled bioreactor

AIMS: This work was undertaken to study the feasibility and the characteristics of a fermented product made of goat milk, using a mixed starter culture of Bifidobacterium animalis and Lactobacillus acidophilus under controlled conditions, and to determine their survival in the fermented milk during refrigerated storage. METHODS AND RESULTS: Goat milk was inoculated with Lact. acidophilus and Bif. animalis mixed starter, fermented in a glass bioreactor with controlled temperature (37 degrees C) and anaerobiosis, and monitored for growth and acidification. The fermented milk was then stored for 10 days under refrigeration, and monitored daily for starter microflora survival and pH changes. Lact. acidophilus viable counts reached a maximum of 7.1 x 10(8) colony-forming units (CFU) ml(-1), and Bif. animalis a maximum of 6.3 x 10(7) CFU ml(-1) by 20 h of fermentation. During refrigerated storage, both strains exhibited a good survival, with viable numbers remaining essentially constant throughout the experiment, whereas the pH of the fermented milk dropped slightly. CONCLUSIONS: Mixed cultures of Bif. animalis and Lact. acidophilus may be used to produce fermented goat milk with high counts of both probiotic strains. SIGNIFICANCE AND IMPACT OF THE STUDY: Goat milk fermented with Bif. animalis and Lact. acidophilus can be manufactured as an alternative probiotic dairy product.