Study on Factors Affecting Aerobial Plate Count in Raw Milk

[Objectives]This study was conducted to investigate the main factors affecting the aerobial plate count in raw milk.[Methods]Drinking water,medicated baths and raw milk under different storage and transportation conditions were detected for the values of aerobial plate count to analyze their effects on the aerobial plate count in raw milk.[Results]Disinfection of drinking water tanks could significantly reduce the aerobial plate count in water.The use of medicated baths before and after milking could effectively reduce the aerobial plate count and had a significant bactericidal effect.The growth of microorganisms in raw milk stored below 4℃was relatively slow.Regularly disinfecting drinking water tanks and disinfecting nipples before and after milking could reduce the aerobial plate count in the tanks and nipples.After raw milk was extruded,the temperature should decrease to 0-4℃within 2 h,and the storage time should not exceed 48 h,which could effectively control the aerobial plate count in raw milk.[Conclusions]This study provides a reference for scientific control of the aerobial plate count in raw milk.

Analysis of 13 kinds of steroid hormones in raw milk using modified QuEChERS method combined with UPLC-QTOF-MS

Thirteen kinds of steroid hormones in raw milk（cow, goat and buffalo milk） were analyzed with ultra performance liquid chromatography-quadrupole time of flight mass spectrometry（UPLC-QTOF-MS） after extraction and cleanup with the modified Qu ECh ERS method. These steroid hormones included 17β-estradiol, estriol, estrone, diethylstilbestrol, progesterone, melengestrol acetate, megestrol acetate, chlormadinone acetate, 19-nortestosterone, metandienone, boldenone, epitestosterone, and testosterone. The limits of detection for the raw milk basing on 3 times the signal to noise ratios（S/N=3） was in range of 0.07-0.51 μg kg^–1, and the limits of quantification（basing on S/N=10 method） covered the ranges from 0.23 to 1.7 μg kg^–1. With matrix external standard method, the substances presented recoveries over the range 74.2–99.7%. Qualitative analysis was also done in the mass/mass spectrum（MS/MS） mode and each debris structure of 13 kinds of steroid hormones was achieved. The methodology was then applied in real raw milk samples which were collected in several areas of China and the progesterone was detected with high level.

A Novel and Reliable Spectrophotometric Method for Determination of Lactoperoxidase Activity in Raw Milk

With 3, 3’5, 5’-tetramethylbenzidine（TMB） as the detection substrate, a reliable and highly selective method was established and optimized for the determination of Lactoperoxidase（LP） activity in raw milk. The method was based on the enzymatic reaction principle, where hydrogen peroxide oxidated TMB in the presence of LP. The optimized conditions of this assay system were obtained, consisting of 20 mmol · L-1 TMB solution, 0.6 mmol · L-1 hydrogen peroxide and 0.1 mol · L-1 Citric Acid（CA）/0.2 mol · L-1 disodium hydrogen phosphate（Na P） buffer（pH 4.8）. TMB detection method was applied to the analysis of LP in milk samples with a practical working concentration range from 2 to 14 mg · L-1. The intra-and inter-batch variation coefficients were all below 5%, indicating a good repeatability. Confirmation test between TMB method and 2, 2-azinobi（3-ethylbenzothiazoline-6-sulphonate） diammonium salt（ABTS） method was carried out, and the results of TMB assay were in accordance with that of ABTS method.

Application of Colligative Properties in Quality Detection of Watering Raw Milk

[ Objective] To investigate the effects of different water amount on freezing point of raw milk. EMetbodl The freezing point of raw milk added water at different proportions was detected by SWC-LG freezing point detector. The linear regression equation was obtained. The reproduc- ibility was checked. The water content in raw milk was calculated according to the standard regression curve. E Result~ When the water content changed from 0 to 10%, the freezing point of raw milk increased linearly. As evidenced by the reproducibility test, the standard deviation and rela- tive standard deviation were less than 1%. The milk concentration obtained by detecting the freezing point of blind milk samples had an absolute er- ror of no more than 0.5%, compared with actual watering milk concentration. [ ConcluMonl Water content in raw milk can be determined by measur- ing freezing point, and this method is reliable and reproducible.

Identification of Pathogenic Germs and Antibiotics Residues in the Raw Milk and Their Effects on Human Health

Milk is a food of great value, it provides more essential nutrient than any other natural food. The presence of pathogenic bacteria and antibiotic residues in milk can cause a real danger to consumers. Effectively, the milk consumption contaminated by bacteria can have an immediate impact which means a toxi-infection. Therefore, the presence of antibiotics residues in milk can constitute an important risk at the allergic and antibiotic resistance cases on the consumer. The present study concerning the pathogens germs identification and Antibiotic residues seeking in milk and their impact on the human health, has been realized on a total number of 80 samples of raw milk resulted from direct sale channel （dairies） throughout Blida different regions localities. The Microbiological analysis has shown only three conform samples to JORA Standards. Really, milk non-conformity results to the microbiological standards consisting on total aerobic mesophilic flora total count, total coliforms, Thermotolerant coliforms E. coli, Faecal streptococcus, Staphylococcus aureus have shown the following contamination rate： 61.25%, 93.75%, 86.25%, 55%, 93.75% and 50%. Salmonella is characterized by a total absence in all analyzed milk samples. Moreover, the antibiotics residues research by Delvotest SP make plainly visible 33 positive samples. Further, two samples of the three which were judged conform to the bacteriology standards has been found contaminated by the antibiotic residues. The analyzed milk quality can be considered as a real danger to the consumption.

Effect of Carbonation on Microbiologic Parameters of Refrigerated Bovine Raw Milk

This study evaluated the effect of carbon dioxide addition on microbiological quality during refrigerated storage of raw milk collected in Curitiba city, Brazil. A three factor-two level full factorial design was used to investigate the effect of the pH （5.8-6.4）, storage time （0-10 days） and storage temperature （5-10 ℃）, on the responses, namely, mesophiles, psychrotrophs, lipolytic psychrotrophs and proteolytic psychrotrophs counts. Results showed that increase in pH and storage time had significant effect on the microbial count. No significant effect of storage temperature was observed for all the microorganisms studied. All responses were well predicted by selected mathematical models, as denoted by coefficient of determination above 0.95.

Evaluation of the Use of Sodium Thiocyanate and Sodium Percarbonate in the Activation of the Lactoperoxidase System in the Conservation of Raw Milk without Refrigeration in the Ecuadorian Tropics

Milk production in Ecuador has enormous economic importance and large-, medium- and small-scale producers all participate in the market. There are multiple climatic regions, and dairy production is present in every one of them. High ambient temperatures in the Ecuadorian tropics represent a key challenge to the conservation of milk in the custody of smallholders. The objective of the present study was to evaluate the efficiency of the application of a chemical activator of the Lactoperoxidase System (LP-s) in the conservation of raw milk, at room temperature, in the Ecuadorian tropics. In the present study, sodium thiocyanate—0.36 g&#183L-1 of milk—and sodium percarbonate—1.36 g&#183L-1 of milk—as an activator of LP-s were used and the pH and microbiological characteristics (total coliforms, Staphylococcus aureus, total aerobes, molds and yeasts) of the milk at different storage times (0, 4 and 8 hours). The results obtained in the present study showed a significant difference between the two groups under study at 8 hours of storage at room temperature in all parameters (except yeasts where there was no growth in the two treatments), being relevant the significant decrease of the bacterial content. Thus the present study shows that the use of sodium thiocyanate and sodium percarbonate in the above described concentrations could be modulating the activation of LP-s that provides an efficient alternative for the conservation of the raw milk without refrigeration, improving the income for losses of the product and obtaining a raw material of good quality for sale or for further processing, mainly for small producers who do not have the economic resources to have refrigeration means for their product and who must transport their milk for considerably longer distances until they arrive at the collection centers or the processing plants for sale, thus showing that the method used in the present study is not only effective but also has a relatively low cost and easy application.

Detection of Glucomacropeptide in Raw Milk Adulterated with Cheese Whey in Ecuador

Milk is one of the products that can be adulterated in many ways affecting the quality of this and its derivatives. Glucomacropeptide (GMP) is a protein that is found only in the whey from the production of fresh cheese, enzymatically obtained from the coagulation of casein and which is commonly used to adulterate fresh or powdered milk. The aim of this study was to determine the adulteration of milk with cheese whey thought a molecular approach, where the glucomacropeptide was collected by sequential precipitation with trichloroacetic acid (ATC) and detected by polyacrylamidododecylsulfate gel electrophoresis (PAGE-SDS), using samples of fresh milk, intentionally adulterated with serum in the proportion of 0%, 1%, 5%, 10% and 15%. The results obtained showed that the detection of glucomacropeptide by electrophoresis was positive in all samples of adulterated milk, evidencing a band of 20.9 kDa in the reading, corresponding to the molecular weight of the GMP, showing that the technique used determines the adulteration in the milk, in a specific and sensitive way, also shows that in the evaluation of physical-chemical and microbiological parameters of milk, there are no significant differences between treatments, except for the pH that tends to decrease as the percentage of serum in the milk increases.

Impact of the residues of detergents and disinfectants used in dairy farms on the results of inhibitor tests for raw milk

The aim of the study was to determine the impact of residues of detergents and disinfectants on the results of most commonly used inhibitor tests for raw milk. Microbiological test (Delvotest SP-NT) and three rapid tests (Charm 3 MRL BL/TET2, Charm ROSA MRL BL/TET and Penzym) were used in the study. Three concentrations (recommended by the manufacturer, 10 times lower and twice higher) of 36 detergents and disinfectants in raw milk were investigated. All methods did not detect concentrations of detergents and disinfectants of alkaline and acid origin 10 times lower than recommended by the manufacturer. 39% of the investigated substances of alkaline origin were detected by Delvotest SP-NT and Penzym;Charm tests showed non-typical results only. Delvotest SP-NT did not detect substances of acid origin;Penzym detected 50% of these substances, Charm tests showed only non-typical results. Delvotest SP-NT and Penzym appeared to be more sensitive to the substances used for teat hygiene and disinfection. The scope of rapid tests (receptor or enzymatic) does not cover the detection of detergent and disinfectant re- sidues in milk. However, according to the non-typical results of the test, it is possible to suspect the presence of these substances in milk. McNemar’s and Cochran’s Q tests were used for statistical analysis of the data.

Selective Lactococcus Enumeration in Raw Milk

The Lactococcus diversity in cow and goat raw milk was investigated. To do so, a protocol had to be established for the specific enumeration of lactococci. Eight agar media and one control medium were analysed to compare their proficiency in evaluating the Lactococcus population in raw milk: M17 Nal, Elliker, modified Elliker, PCA + milk, modified KCA, modified Chalmers, Turner, FSDA. The M17 medium was used as reference. Eighteen pure strains were tested on these media for their selectivity towards lactococci: six Lactococcus species or subspecies, three Leuconostoc, three Enterococcus, two Lactobacillus, one Streptococcus thermophilus, one Pseudomonas fluorescens, one Escherichia coli and one Staphylococcus aureus. All these bacteria were chosen for their regular presence in raw milk. The KCA medium proved to be the most selective towards lactococci, on condition that 1) we discriminated the colonies using the catalase test and 2) we subtracted the Enterococcus population counted on BEA. However, it was not possible to separate the Streptococcus from the Lactococcus colonies on KCA. The “Lactococcus-like” population including these two genera was estimated at a mean level of 3.18 log(cfu)/mL and 4.14 log(cfu)/mL in cow and goat raw milk respectively. This is consistent with the data already published.

Establishment and Optimization of HPLC-MS/MS for Detection of Progesterone Residue in Raw Milk

In order to establish an HPLC-MS/MS method for detecting progesterone in raw milk,raw milk was extracted with methanol,and then determined by HPLC-MS/MS after the purification with a C18 solid phase extraction column. Qualitative determination was performed according to retention time and selective ion abundance ratio,and quantification was performed by external standard method. The results showed that progesterone had a good linear relation in the range of0. 1-5. 0 ng/ml,with a correlation coefficient of 0. 999 9. The detection limit of the established method was 0. 02 μg/kg,and the quantification limit was0. 04 μg/kg. In the standard addition range of 0. 1-5. 0 ng/ml,the recovery ranged from 79. 6% to 105. 1%,with relative standard deviation≤8. 9%. Compared with the industry standard,the detection limit and the quantification limit of the established method are significantly reduced,and the sensitivity of the method is enhanced,so this method is suitable for the detection of progesterone residue in fresh milk in pastures.

A Modified Selective Medium Containing Benzalkonium Chloride (BKC) for the Isolation of <i>Pseudomonas aeruginosa</i>from Raw Milk

A modified selective medium (modified Cetrimide Agar, mCA) consisting of 200 μg/mL benzalkonium chloride (BKC) was developed for the isolation of Pseudomonas aeruginosa from raw milk. Initially, a total of 55 isolates were obtained from 14 raw milk samples collected from several dairy plants in Ankara, Turkey. Among these isolates, 19 were identified as Pseudomonas aeruginosa, 28 as Pseudomonas fluorescens, 4 as Acinetobacter baumannii, 2 as Enterobacter intermedium, 1 asEnterobacter agglomerans, and 1 as Escherichia coli using Microbact biochemical test kit. BKC was chosen as a selective agent to suppress growth of competitive flora because it is very effective against a wide range of Gram-negative bacteria while P. aeruginosa is resistant. MICs (minimum inhibitory concentration) for BKC were determined by agar dilution method. The concentration of 200 μg/mL BKC inhibited competitive flora, while 90% of P. aeruginosa strains were resistant. When the results of enumeration of P. aeruginosa and other Gram (-) bacteria in Cetrimide Agar (CA) and mCA were compared, it was observed that mCA was more selective than the standard CA in preventing the growth of competitive flora especially of P. fluorescens.

Detection of Pathogenic Bacteria <i>Staphylococcus aureus</i>and <i>Salmonella</i>sp. from Raw Milk Samples of Different Cities of Pakistan

Food-borne diseases are the main public health problem throughout the world. Milk is important component of human diet including fats, proteins, vitamins and minerals. It is a best source of calcium and phosphorus. Different types of pathogenic bacteria like S. aureus and Salmonella enter in milk and then multiply, after multiplication they become active in causing diseases. These bacteria create serious problems for human health. This study aimed to isolate and identify pathogenic bacteria Staphylococcus aureus and Salmonella from raw milk samples of different cities of Pakistan. Primary screening of raw milk samples was done on the basis of morphological, cultural and biochemical techniques. The final identification was made using 16SrRNA sequence analysis. A total of 200 raw milk samples were collected from different cities of Pakistan. Selective medium xylose lysine deoxycholate agar (XLD) and Mannitol salt agar were used for the identification of Salmonella sp. and S. aureus. Staphylococcus aureus produced yellow colonies with yellow zones on Mannitol salt agar. Staphylococcus aureus exhibited gram-positive character with purple coloration and it was detected as cocci-shaped. Biochemically 91 (45%) samples enhibited Catalase, Coagulase, DNase, Urease, Citrate, fermentation tests positive and indole, oxidase and H2S tests negative with nonmotile character, indicating the presence of Staphylococcus aureus. Salmonella sp. was detected as gram negative rods with pink coloration on gram staining. Biochemically 87 (43%) samples revealed catalase, citrate, H2S and fermentation tests positive while oxidase, DNase, Indole and urease tests negative, indicating the presence of Salmonella sp. in these samples. Of the 200 samples tested, 43% were positive for Salmonella, while 45% samples were contaminated with S. aureus. The 16SrRNA sequence analysis confirmed the results of biochemical and cultural characterization by depicting 99% identity of samples with S. aureus and 98% identity with Salmonella spp. The occurrence of high percentage of these pathogenic bacteria in raw milk may be linked to its contamination at the time of collection, processing, strorage and distribution. This quantitative data could be utilized to better establish the appropriate levels of protection for raw milk, dairy products and processing technologies.

Microbial quality and associated health risks of raw milk marketed in the Tanga region of Tanzania

Objective:To evaluate micmbial quality and associated health risks of raw milk marketed in the Tanga region of Tanzania.Methods:A microbial quality assessment of marketed raw milk was undertaken by evaluating 59 samples of milk from selling points(collecting centres =15),bicycle boys(12) and kiosks/restaurants(32) in Tanga city during April-May 2005.Quality and milkborne hazards were assessed using a combination of tests in order to quantify the occurrence of Brucellosis(milk ring test),Escherichia coli(E.coli) O157:H7(culture),the coliforra bacteria as well as standard plate count(SPC).Specific gravity(SG) determination was used as an indicator of adulteration.Results:The mean coliform plate count(c.f.u/mL) of milk handled by bicycle boys(4.2×10~6) was significantly higher than that handled by collecting centres(3.0×10~6) and kiosk/ restaurants(1.4× 10~6),respectively(P 【 0.05).Of the 59 milk samples collected,33(56%) were Brucella milk ring test(MRT)-positive and 78%and 17%of the samples graded satisfactorily based on SG and coliform plate counts as prescribed by East African Community standards for raw milk.There was no verocytotoxigenic E.coli(VTEC) O157:H7 in any of the milk samples collected and analysed during the present study.Conclusions:It can be concluded that raw market milk in the study area is of poor bacteriological quality and hazardous for human consumption. This highlights the need to implement good hygiene practices and effective monitoring from production through the delivery chain to the consumer.Further studies are needed for detection of toxins that are produced by E.coli,other pathogenic spore forming bacteria(Bacillus spp.and Clostridium spp.) and other harmful microorganisms.

Comparative Analysis of the Purchase Price of Raw Milk in the World

This paper selects 20 countries from the major dairy producing continents such as Oceania,the Americas,Europe and Asia,for the comparative analysis of the purchase price of raw milk in the world. Based on the summarization of general features of the world raw milk prices,this paper elaborates the fluctuations in the purchase price of raw milk in Oceania,the Americas,Europe and Asia,respectively,and carries out the comparative study of the gap between the domestic purchase price of raw milk and the world purchase price of raw milk.

Survey on Raw Milk Quality in Kosovo

In Kosovo, a new regulation on quality standards and grade of fresh milk is valid since January 1, 2007. The regulation was based on the respective EU-regulation and has an ambitious time frame with a transition period of only three years. In order to estimate the impact of this new regulation, a survey on the quality of raw milk delivered to the Kosovar dairies was carried out from January to May 2007. The aim was to get a reliable picture of the current raw milk quality in the dairy channel in Kosovo, to discuss the findings with the relevant actors of the dairy sector and the government, and to draw the necessary conclusions. In total 364 milk samples, from the leading 14 dairies constitute the basis for the statistical analyses of this study. The four most important parameters of raw milk quality: TBC, SCC, FP and AB were analyzed. Regarding TBC, the results show that around 20% of samples meet the Kosovo standard 2008 (< 500,000 CFU/ml) and only around 10% meet the (higher) Kosovo standard 2009 (<100,000 CFU/ml) while for SCC, around 80% of the samples meet the Kosovo standard 2008 (<600,000 cells/ml) and 66% meet the (higher) Kosovo standard 2009 (<400,000 cells/ml). Therefore at the moment the problem of high microbiological content is more prominent than the one of high somatic cell count. Beside this, in one third of the samples, the freezing point is at least questionable. In 2.2% of the samples antibiotics could be proven—a major risk for public health. Raw milk quality in Kosovo still is very poor and must be improved in order the dairy processors be able to produce qualitatively good end products and therefore can compete with imported dairy products or export their products.

Characterization of <i>Lactobacillus</i>Strains Isolated from Bovine Raw Milk for Probiotic and Technological Properties

One hundred strains isolated from bovine raw milk, obtained from different farms, were subjected to different in vitro stress typical of gastrointestinal tract. Twelve strains were able to tolerate pepsin at pH 2, pancreatin and bile salts (0.3%). These bacteria were identified using 16S rRNA gene sequencing. Eight isolates were Lactobacillus plantarum and four were Lactobacillus fermentum. They were not able to degrade mucin and they were γ-haemolytic. All strains had antibacterial activity against Staphylococcus aureus, Listeria monocytogenes and Salmonella thyphimirium. However, only six strains inhibited Escherchia coli. All these showed ability for autoaggregation and/or hydrophobicity properties. They were also characterized in respect to their technological properties. Important acidification and low proteolytic and lipolytic capacities were detected for all strains. In addition, they were able to produce exopolysaccharides and grow at hot and cold temperatures. These bacteria may be used further for manufacturing of functional foods and confirming their suitability as probiotic starter cultures.

A raw milk service platform using BP Neural Network and Fuzzy Inference

An important index for raw milk storage in a dairy farm is the raw milk storage temperature which directly reflects the raw milk quality.Meanwhile,it’s hard to centrally manage numerous dairy farms which are not distributed in the same place.We aim to build a kind of raw milk monitoring and warning equipment,gateway and cloud service platform to solve these problems.The raw milk monitoring and warning equipment and service platform were designed to monitor the raw milk temperature in the refrigerated storage tank and provide a warning alarm if an exception occurred.Data-driven modeling was used for acquiring,cleaning,and utilizing data to solve the raw milk storage problems.The raw milk monitoring and warning management systemprovided away of predicting and warning for raw milk storage using BP Neural Network and Fuzzy Inference.The test showed that the BP Neural Network and Fuzzy Inference model built in this paper had a good performance in predicting the raw milk storage temperature and reflecting the variation of raw milk temperature in raw milk storage process.The platform and models provided a method to manage the raw milk in dairies and prevent the raw milk from deteriorating caused by the rising temperature.

Spoilage potential of psychrotrophic bacteria isolated from raw milk and the thermo-stability of their enzymes

The storage and transportation of raw milk at low temperatures promote the growth of psychrotrophic bacteria and the production of thermo-stable enzymes, which pose great threats to the quality and shelf-life of dairy products. Though many studies have been carried out on the spoilage potential of psychrotrophic bacteria and the thermo-stabUities of the enzymes they produce, further detailed studies are needed to devise an effective strategy to avoid dairy spoilage. The purpose of this study was to explore the spoilage potential of psychrotrophic bacteria from Chinese raw milk samples at both room temperature （28 ℃） and refrigerated temperature （7 ℃）. Species of Yersinia, Pseudomonas, Serratia, and Chryseobacterium showed high proteolytic activity. The highest proteolytic activity was shown by Yersinia intermedia followed by Pseudomonas fluorescens （d）. Lipolytic activity was high in isolates of Acinetobacter, and the highest in Acinetobacter guillouiae. Certain isolates showed positive ^-galactosidase and phospholipase activity. Strains belonging to the same species sometimes showed markedly different phenotypic characteristics. Proteases and lipases produced by psychrotrophic bacteria retained activity after heat treatment at 70, 80, or 90 ℃, and proteases appeared to be more heat-stable than lipases. For these reasons, thermo-stable spoilage enzymes produced by a high number of psychrotrophic bacterial isolates from raw milk are of major concern to the dairy industry. The results of this study provide valuable data about the spoilage potential of bacterial strains in raw milk and the thermal resistance of the enzymes they produce.

Portable Analyzer for Rapid Analysis of Total Protein, Fat and Lactose Contents in Raw Milk Measured by Non-dispersive Short-wave Near-infrared Spectrometry

A novel portable analyzer for raw milk quality control during the material purchase at dairy plants was developed, by which the percentages（mass fraction） of main components including total protein, fat, and lactose of an unhomogenized milk sample could be determinated in 1 min with the help of non-dispersive short-wave near-infrared （NDSWNIR） spectrometry in a wavelength range from 600 nm to 1100 nm and multivariate calibration. The analyzer was designed with a single-beam optical system, which comprised a temperature control module, a multi-channel narrow-band light source（16 wavelengths）, a glass absorption cell with 15 mm sample thickness, a silicon photodiode detector, several compound lenses and a recorder module. A total of 80 raw milk samples were collected at a dairy farm twice a month for 4 months. The samples were scanned with a common UV-Vis-NIR spectrometer and analyzed according to China GB standard methods. The uninformative variables elimination（UVE） method was carried out on the spectrum data and the percentages of main components of all the samples to choose the peak emitting wavelength of each channel of the light source. Another 90 raw milk samples were collected from the same dairy farm thrice a month for 3 months. The samples were analyzed according to China GB standard methods and with the proposed analyzer. The percentages of the main components and the NDSWNIR absorption data of the samples were used for the construction and validation of the multivariate calibration model with partial least squares（PLS） method. The root-mean-square errors of prediction（RMSEP） of total protein, fat and lactose were 0.201, 0.172 and 0.247 and the coefficients of correlation（R） were 0.932, 0.981 and 0.933, respectively.