Detection of Staphylococcus aureus in Dairy Products by Polymerase Chain Reaction Assay

A polymerase chain reaction （PCR） assay was employed for direct detection of Staphylococcus aureus without enrichment in dairy products. A solvent extraction procedure was successfully modified for the extraction of Staphylococcus aureus DNA from artificially contaminated whole milk, skim milk, and cheese. A primer targeting the thermostable nuclease gene （nuc） was used in the PCR. A DNA fragment of 279 bp was amplified. The PCR product was confirmed by DNA sequencing. In this study, the PCR, GB-4789.10-94, Perifilm RSA.Count Plate, and Baird-Parker ＋ RPF Agar were compared. The sensitivity of the PCR was 10 CFU mL^-1 of whole milk, skim milk, and 55 CFU g^-1 of cheese. The developed methodology allowed for detection of Staphylococcus aureus in dairy products in less than 6 h. The time taken for the development of this PCR assay was 12-24 h, less than the time taken by the general PCR assay using the enrichment method, and the coincidence rate of this developed PCR was 94.3%, the sensitivity was 100%. It was a rapid, sensitive, and effective method for PCR to detect Staphylococcus aureus in milk and milk products.

Detection of Patulin in Dairy Products by ELISA

The content of patulin in dairy products was detected by rapid ELISA assay. The pretreatment of samples was simple, with wide range of application. The standard product showed good linear relationship with the range of 0-5.4 μg/kg, and the linear relationship reached 0.999 3, with high sensitivity. It took shorter time, with a total time-consumption of 1 h. Moreover, it had good repeatability for analytical requirements.

Research Progress on Detection Methods of Melamine and Cyanuric Acid Residue in Dairy Products and Feedstuff

[Objective] More accurate, rapid and sensitive method of melamine and cyanuricacid residue in dairy products and feedstuff were re- viewed. [ Method] Physicochemical properties, metabolism, uses, harm and detection methods of melamine and cyanuric acid were analyzed and described. [ Result] Melamine and cyanuric acid, when used alone, were slightly toxic, but long -term intake could lead to animal reproductive and urinary system damage. [ Condusion] Establishing a more sensitive, fast and easy to popularize detection method for elarnine and cyanuricacid res- idue in dairy products and feedstuff was necessary.

Study on Quality and Safety Trust Early Warning of Dairy Products Based on Statistical Process Control

In order to solve such problems as lack of dynamic evaluation system in evaluation of quality and safety trust of dairy products,and weak awareness of prevention,it is necessary to introduce the statistical process control into the quality and safety trust evaluation system of dairy products,and establish quality and safety trust early warning model for dairy products,so as to determine the control limit of control chart and carry out early warning according to eight criteria. According to the empirical results,the statistical process control is helpful for finding the hidden process risks and providing the necessary basis for enterprises taking positive measures to raise the confidence of consumers.

Application of Liquid Chromatography-High Resolution Time-of-flight Mass Spectrometry in the Detection of Raw Milk and Dairy Products

Milk and dairy products are more and more popular with consumers due to their various nutrients, and their quality and safety issues have always been concerned. Therefore, the development of rapid, accurate and simple screening techniques is of great significance. Liquid chromatography-high resolution time-of-flight mass spectrometry has high-resolution and high-throughput detection functions, and has gradually begun to be applied in the detection of milk and dairy products. This paper summarized the application of milk and dairy products in liquid chromatography-high resolution time-of-flight mass spectrometry, laying a foundation for the development of new methods.

Search of Salmonella in Meat and Dairy Products

The epidemiology of Salmonella involves food, especially meat and dairy products. These have a high salmonella outbreak in the summer. The majority of Salmonella enteritis in young children occurs in the form of scattered cases. At least 25% of summer gastroenteritis in young children is caused by Salmonella. In Western Europe, S. typhimurium accounts for nearly 70% of isolates. The objective of this study was to investigate the Salmonella contaminating meat and dairy products as well as define the percentages of contamination by Salmonella from 2004 to 2006, by the Department of Hygiene of Tunis. For this study, we collected samples in various motherboard solutions, and conducted a pre-nonselective enrichment in selective enrichment in isolation and identification and ultimately biochemical confirmation. One hundred and sixty two samples, 125 samples of meat products including 68 samples of red meat （beef and sheep, beef, offal and Merguez） and 57 samples of poultry （chicken and turkey）, 37 samples of milk products which included 32 samples of cheese and five samples milk, were analysed microbiologically from 2004 to 2006, in the Health Service in Tunis. These analyses include the detection and enumeration of Salmonella. From 2004 to 2006, the rate of infections by the Salmonella, meat and dairy products were： 55.9% for red meat, 71.9% for poultry, 68.8% for cheeses, 40% for milk. The meat of poultry is contaminated with Salmonella that the cheeses, which are more than red meats, which are also more contaminated than milk. This might be due to a lack of hygiene throughout the circuit processing （slaughter, transport, processing, etc.）. The increased risk of contamination of milk products by Salmonella is proportional to the manipulation done on these products. The latter must be handled by pasteurization and sterilization.

The Consumption Preferences of Milk and Dairy Products of Undergraduate Students

Human has different stages in their life as from babyhood to adult. The healthy and balanced diet preferences of people play an important role in each human life parts. Especially milk and dairy products are necessary for human health because of their nutrition value and body functions. One of the parts of people life is university life. Starting university is a turning point in terms of eating habits, since food choices responsibility of university students increases in this period. According to the researches, increasing availability of fast foods, changes in living arrangements, life experiences, expectations, preferences and beliefs related with food selections are most common reasons regarding dietary choices in this young adults group. University students had drinking milk habits in primary school but most of them lose their habits during university life. The students＇ first preferences were cheese and then yogurt and finally milk. A very little part of university students consume milk and dairy products regularly. The consumption habits and milk and dairy product catering of university students were examined. The consumption preferences of milk and dairy products of the students in different Universities are reviewed in this review.

Application of Six Sigma DMAIC Method in Improving the Good Rate of Blank Value of Cytological Method for Dairy Products

In this paper,the six Aigma DMAIC method was used to systematically analyze and study the process affecting the good rate of blank value of cytological method for dairy products.Through data collection,analysis and verification in each link,the room for improvement in the experimental process was identified.C&E matrix and FMEA were used to analyze the factors affecting the good rate of blank value.Through the DOE experiment design method and risk analysis,the main influencing factors were optimized and improved.The optimized experimental conditions were:silica gel activation temperature(500±50)℃,activation time(23±1)h,cells adherent rate(95±1)%,and single-use of 1.5 mL conical flask.Under the above conditions,the good rate of blank value of cytological method was improved from 52.8%to 100%.The improvement of these conditions is of great significance to ensure the accuracy of results,save the testing cost and improve the testing efficiency.

Two perspectives of Listeria monocytogenes hazards in dairy products:the prevalence and the antibiotic resistance

Listeria monocytogenes is among the most food-borne pathogens.It has the ability to grow over a range of temperature,including refrigeration temperature.Foods kept in refrigerator more than the prescribed period of time create an opportunity for the occurrence of Listeria monocytogenes.As this review shows,the prevalence of L.monocytogenes has more likely evident in pasteurized milk than other dairy products,such as raw milk.Inadequate temperature and faults in technology during pasteurization can be the disposing factors for the presence of the organism in dairy products.The organism,on the other hand,has been found to be resistant to those commonly known antibiotics that have human and veterinary importance,namely,ampicillin,Tetracycline,and chloramphenicol,streptomycin,erytromycin,penicillin G.,and others.Resistance ability of the organism can be mediated by different natural and acquired resistance mechanisms,such as self-transferrable plasmids,mobilizable plasmids,and conjugative transposons.The emergence and spread of antibiotic resistance of L.monocytogenes has serious public health and economic impacts at large.This paper has reviewed the prevalence and the antibiotic resistance of L.monocytogenes isolates of dairy products and the strategic mechanisms of the organism develop resistance against the antibiotics.

Melamine-imprinted electrochemical sensor of graphene/ionic liquid composites and its use for the detection of melamine in dairy products

By exchanging the conventional role of functional monomer and template molecules,we develop a new molecu-larly imprinted nanospheres with grape grain structures based on multi-hydrogen bonding interactions between melamine and 6-aminouracil.Molecular imprinting-electrochemical sensor was established with the assistance of graphene and ionic liquids.The content of melamine in dairy products was detected by the molecular imprinting-electrochemical sensor.The detection limit was determined to be as low as 1.57×10^(−3) mg kg^(-1).

Calcium-fortified fresh milk ameliorates postmenopausal osteoporosis via regulation of bone metabolism and gut microbiota in ovariectomized rats

The aging of the global population has made postmenopausal osteoporosis prevention essential;however,pharmacological treatments are limited.Herein,we evaluate the effect of calcium-fortified fresh milk(FM)in ameliorating postmenopausal osteoporosis in a rat model established using bilateral ovariectomy.After 3 months of FM(containing vitamin D,and casein phosphopeptides,1000 mg Ca/100 g)or control milk(110 mg Ca/100 g milk)supplementation,bone changes were assessed using dual-energy X-ray absorptiometry,microcomputed tomography,and bone biomechanical testing.The results revealed that FM can regulate bone metabolism and gut microbiota composition,which act on bone metabolism through pathways associated with steroid hormone biosynthesis,relaxin signaling,serotonergic synapse,and unsaturated fatty acid biosynthesis.Furthermore,FM administration significantly increased bone mineral content and density in the lumbar spine and femur,as well as femoral compressive strength,while improving femoral trabecular bone parameters and microarchitecture.Mechanistically,we found that the effects may be due to increased levels of estrogen,bone formation marker osteocalcin,and procollagen typeⅠN-propeptide,and decreased expression of the bone resorption marker C-telopiptide and tartrate-resistant acid phosphatase 5b.Overall,the findings suggest that FM is a potential alternative therapeutic option for ameliorating postmenopausal osteoporosis.

Current Status of Camel Dairy Processing and Technologies: A Review

Camel milk is unique because it is not easily processed into different dairy products that are common for cow milk. It lacks β-lactoglobulin and has low κ-casein that hinders processing of camel milk into different dairy products. Hence it needs different processing methods and technologies. To this effect attempts were made to manufacture dairy products such as feta cheese, soft brined cheese, and fermented milk from camel milk that had been produced at laboratory level. Camel milk powder has also been manufactures and marketed in Middle East and beyond. Currently there are remarkable progresses in camel dairy technologies that paved the way for production of different camel dairy products at small, medium and large scale. A number of experiments were conducted on camel milk processing technologies from preservation of camel milk using lactoperoxidase system activation using hydrogen peroxide (H2O2) and thiocyanate as well as by H2O2 producing lactic acid bacteria (LAB) to metagenomic characterization of LAB isolated from spontaneously fermented camel milk. Therefore, this review paper is going to present current status of camel dairy technologies in Ethiopia.

An Analysis of Government Behavior in China's Dairy Industry

The quality of agricultural products should be regulated and guided by the industrial association consisting of various links of agricultural production chain. The government has to purchase the regulatory services from agricultural associations. In the production of dairy products in China,the improper government intervention has been in violation of the socialist market economic law,resulting in damage to the node enterprises on the dairy production chain. Therefore,it is necessary to establish the agricultural associations to ensure the quality of agricultural products.

Effect of dietary phosphorus content on milk production and phosphorus excretion in dairy cows

Background：Phosphorus（P） supplementation is costly and can result in excess P excretion.This study investigated the effects of reducing dietary P on milk production and P excretion in dairy cows over a full lactation.Method：Forty-five multiparous Holstein dairy cows were divided into 15 blocks according to expected calving date and previous milk yield,and assigned randomly to one of the three dietary treatments：0.37,0.47,and 0.57%P（DM basis）;these P levels represent the NRC recommendations,Chinese recommendations,and the amount of dietary P commonly fed by Chinese dairy farmers,respectively.Average daily feed intake was calculated from monthly data on feed offered and refused.Milk yields of individual cows were recorded weekly,and milk samples were taken for analysis of protein,fat,solids-not-fat,lactose,and somatic cell count.Blood samples were collected on days-6,-3,0,3,6 relative to calving,and then monthly throughout lactation,and analyzed for P and Ca concentrations.Spot samples of feces and urine were collected for 3 consecutive d during weeks 12,24,and 36,and P concentrations were analyzed.Reproduction and health data were recorded.Results：Dietary P did not affect dry matter intake or milk yield（P〉 0.10）.Milk fat content was slightly higher in cows fed 0.37%P than in cows fed 0.47%P（P = 0.05）.Serum concentrations of P and Ca did not reflect dietary P content（P〉 0.10）.Fecal and urinary P both declined linearly（P〈 0.05） as dietary P decreased from 0.57 to0.37%.Fecal P content was 25%less when dietary P was 0.37%compared to 0.57%.Health events and reproductive performance were not associated with dietary P content（P〉 0.05）.Conclusions：Lowering dietary P from 0.57 to 0.37%did not negatively affect milk production,but did significantly reduce P excretion into environment.

Influence of main dietary chemical constituents on the in vitro gas and methane production in diets for dairy cows

Background： Modification of chemical composition of diets fed to dairy cows might be a good strategy to reduce methane（CH4） production in the rumen. Notable reductions of CH4 production compared to conventional highroughages rations were more frequently observed for very concentrated diets or when fat supplements were used. In these cases, the reduction in the gas emission was mainly a consequence of an overall impairment of rumen function with a reduction of fiber digestibility. These strategies do not always comply with feeding standards used in intensive dairy farms and they are usually not applied owing to the risks of negative health and economic consequences.Thus, the present study evaluated the effects of seven commercial diets with contents of neutral detergent fiber（NDF）,protein and lipids ranging 325 to 435 g/kg DM, 115 to 194 g/kg DM, and 26 to 61 g/kg DM, respectively, on in vitro degradability, gas（GP）, and CH4 production.Results： In this experiment, changes in the dietary content of NDF, crude protein（CP） and lipids were always obtained at the expense or in favor of starch. A decreased of the dietary NDF content increased NDF（NDFd） and true DM（TDMd） degradability, and increased CH4 production per g of incubated DM（P 〈 0.001）, but not that per g of TDMd. An increase of the dietary CP level did not change in vitro NDFd and TDMd, decreased GP per g of incubated DM（P 〈 0.001）, but CH4 production per g of TDMd was not affected. An increased dietary lipid content reduced NDFd, TDMd,and GP per g of incubated DM, but it had no consequence on CH4 production per g of TDMd.Conclusions： It was concluded that, under commercial conditions, changes in dietary composition would produce small or negligible alterations of CH4 production per unit of TDMd, but greater differences in GP and CH4 production would be expected when these amounts are expressed per unit of DM intake. The use of TDMd as a standardizing parameter is proposed to account for possible difference in DM intake and productivity.

Ingredients from integral valorization of Isabel grape to formulate goat yogurt with stimulatory effects on probiotics and beneficial impacts on human colonic microbiota in vitro

Isabel grape(IG)products have high contents of phenolic compounds and fiber recognized for their positive impacts on microorganisms associated with health benefits to host.This study evaluated the effects of goat yogurts formulated with ingredients from IG integral valorization on the growth and metabolism of different probiotic strains,as well as on the population of selected bacterial groups and metabolic activity of human colonic microbiota in vitro.Goat yogurts with IG ingredients(IGI)stimulated the growth of tested Lactobacillus and Bifidobacterium probiotic strains during a 48-h cultivation,as well as decreased the pH values and enhanced the organic acid production.Goat yogurts with IGI increased the population of Lactobacillus spp.and Bifidobacterium spp.during a 24-h in vitro colonic fermentation.A stable Firmicutes:Bacteroidetes ratio close to 1 was found in media with goat yogurt formulations during the colonic fermentation,being similar to the effect caused by fructooligosaccharides.Goat yogurt formulations with IGI caused increased production of short-chain fatty acids and sugar consumption during colonic fermentation.Goat yogurts with IGI should be a valuable strategy for development of novel added-value foods with beneficial effects on gut microbiota and human health.

A Survey on Occurrence of Melamine and Its Analogues in Tainted Infant Formula in China

Objective To investigate the occurrence and concentrations of melamine and its analogues in tainted infant formula and to identify the etiologic factors for the urinary stones epidemic in infants and young children in China in 2008. Methods Sanlu infant formula samples were collected from families of the affected children in Gansu province, and markets in Gansu and Hebei provinces and Beijing city. Melamine and its analogues, including cyanuric acid, ammeline, and ammelide were measured by gas chromatography/tandem mass spectrometry. Results High prevalence and concentrations of melamine were found in Sanlu infant formula samples, with low concentrations of cyanuric acid, ammeline and ammelide. Melamine were detected in 87 out of 111 Sanlu infant formula samples with a range of 118 to 4 700 mg/kg, Conclusion The results provide strong evidence for melamine as the etiological factor for the urinary stones epidemic in infants and young children in China in 2008.

Milk Production Practices on Family Farms Located North of the State of Espirito Santo, Brazil

In Brazil, milk production is a key sector for income generation, tax collection and much of the milk produced comes from family farms. The present study was aimed to assess the conditions of milk production on 30 farms in the city of S~ Mateus, to the North of the state of Espirito Santo, Brazil. Data were obtained through questionnaires sent to producers according to the legislation of the Brazilian Ministry of Agriculture. The questions included type of milking, hygiene practices and health status of milkers, mastitis control and source and others. Milking was manually done in all farms, and only 40,0% of milkers washed their hands and forearms before milking, and 13.0% used antiseptic solutions after washing. None of the farms performed the pre-dipping and post-dipping procedures. Control of mastitis was not performed in 94.0% of the farms and none of them performed the CMT test. A high degree of non-conformity was observed in the family farms. These data demonstrate the need for training farmers in good agricultural practices. This would contribute to achieving better quality milk, and ensure the sustainability of the segment in the Northern region of the state of Espirito Santo, Brazil.

Controlling the Risk of Bacillus in Food Using Berries

Introduction: Increasing the shelf life of foods without the addition of synthetic additives is a demand from both producers and consumers. Spore-forming bacteria are a problem in the food industry. To reduce their impact, it is necessary to use complex technologies, as well as ingredients with antibacterial or antibiotic properties. The aim of this study was to develop initial symbiotic combinations between lactic acid bacteria and berries to control food quality. The relevant ability of lactic acid bacteria in the presence of berry additives to inhibit the growth of Bacillus strains that degrade bakery products and dairy products was investigated. The antibacterial effect of berries on the growth of Bacillus mesentericus was studied. Methods: In this study was used inhibition zone test, also called Kirby-Bauer Test. The growth rate of bacteria was based on the measurement of the optical density at 600 nm (OD600). The method of Thompson et al. has been used to research the development of ropiness disease in wheat bread samples. Results: The diameter of the Bacillus pumilus growth inhibition zones under the berries action was as follows: aronia -18.0 ± 0.6 mm;raspberry -16.0 ± 0.4 mm;strawberry -15.0 ± 0.5 mm. Lactic bacteria in the presence of berry additives showed a growth rate, measured by optical density (OD) at 600 from 0.073 to 0.651 (for aronia) from 0.071 to 0.609 (for raspberries), from 0.073 to 0.597 compared to the increase in environments without added fruit, which amounted to -0.050 to 0.410. In the yogurt with added fruit, a synergism was formed with Streptococcus thermophilus, Lactobacillus delbrueckii subsp. Bulgaricus, Lactococcus lactis subsp Lactis biovar diacetilactis. The influence of fat-soluble extracts of sea buckthorn, rose-hip, and hawthorn fruits on the development of ropiness disease when storing wheat bread was investigated. The general Pearson coefficient (microbial count and pH) for all fruit yogurt samples is 0.95066. Conclusion: The combined use of lactic acid bacteria and berries (aronia, raspberry and strawberry) had a synergistic effect on the risk posed by Bacillus bacteria. 1% of fat-soluble extract from the vegetable matter reduced the risk of ropiness disease in wheat bread. This is due to the cumulative effect of the berries chemical composition (antioxidants, organic acids, etc.), increased acidity, lowered pH, and water activity of the food environment, below the development values of Bacillus.

Testing for Sources of Irreversible Consumer Demand

The existence of irreversible demand is tested, whereby price increases induce a different absolute magnitude of quantity change than price decreases. Irreversibility is potentially likely in retail food settings for storable products that are consumed regularly and can affect pricing strategy performance. If irreversibility exists, the subsequent research question for storable product demand is whether loss aversion effects dominate stockpiling effects, or vice versa. A two-period theoretical model is developed, which predicts more elastic responses to downward price movements via stockpiling, but empirical tests on secondary data are needed to evaluate offsetting loss aversion effects. A variant of the Rotterdam demand model is developed to allow differential response to price increases and decreases. The model is applied to scanner data of short periodicity （weekly in this case）, which are necessary to measure meaningful demand responses to food price changes. The products selected are U.S. cheeses and table spreads that are storable over multiple weeks. The results suggest that stockpiling dominates loss aversion. One potential cause of this behavior may be that marketers asymmetrically provide consumers with more reference price information when lowering prices, but not when raising prices. When stockpiling effects dominate, given the typically price-elastic store-level demand for food products, high-low pricing strategies should produce higher revenue. Regarding measurement of average demand response, reversible demand models applied to weekly data may overestimate own-price elasticities.