Proper Pasteurization Research Articles

Conditions and Antimicrobial Resistant Profiles of Campylobacter Species from Cow Milk Samples in Oromia Region, Ethiopia

Campylobacter is one of the major causes of gastroenteritis and is commonly transmitted through the consumption of raw milk or improperly pasteurized milk. A cross-sectional study was conducted from January 2019 to March 2020 in four study sites in the Oromia region of Ethiopia to isolate, identify, and estimate the prevalence of Campylobacter species in milk samples and to determine their antibiotic susceptibility pattern. A total of 384 cow milk samples were randomly chosen from 192 samples of raw milk from farmers and collectors and 192 samples of pasteurized milk from processors and retailers. Standard bacteriological techniques and PCR were used to isolate and identify Campylobacter spp. Of the total 384 milk samples, 35 (9.1%) were found to be positive for Campylobacter spp. The prevalence of Campylobacter spp. was highest in collector raw milk (13.5%), farmer raw milk (12.5%), and pasteurized milk (5.2%).The antibiotic susceptibility test was performed using the disc diffusion method. The most prevalent Campylobacter spp. isolated from milk samples was Campylobacter jejune (C. jejuni) (100%). The overall prevalence of Campylobacter in dairy value chains, including producer, collector, processor, and retailer, was 12.5%, 13.5%, 5.2%, and 5.2%, respectively. Cold storage, material type for making collection rooms, calibrating the pasteurizer machine, restricting milk handlers that are sick, means of transportation, and maintaining temperature during transportation had a statistically significant association. 100% and 8.6% of the Campylobacter isolates were sensitive to ciprofloxacin and chloramphenicol, respectively. However, all of the isolates were resistant to ampicillin, clindamycin, oxytetracycline, and trimethoprim. Moreover, 80% of the C. jejuni were resistant to tetracycline and streptomycin. 26% of the species developed ciprofloxacin degradation. The result of this study revealed the prevalence and risk factors of Campylobacter species in raw and pasteurized milk samples. Hence, there is a chance of acquiring infection via the consumption of raw or undercooked milk. Thus, the implementation of hygienic practices from the producer to the retailer's market, proper handling to avoid cross-contamination and proper pasteurization are very important in preventing Campylobacter infection.

Development of beetroot extract-based rapid chromogenic test to ascertain the proper pasteurization of milk

Pasteurization is a standard method to prolong the shelf life of milk by preventing the growth of spoilage and pathogenic microorganisms. Alkaline Phosphatase (ALP) activity tests (qualitative and quantitative) are recommended and widely used methods to ascertain the proper pasteurization of milk. However, the traditional methods are time-consuming. Therefore, those methods are difficult in field testing conditions, especially in rural-based dairy industries. In the present study, a simple, quick, safe, and economical chromogenic test protocol based on the ALP activity was developed to ascertain the proper pasteurization of milk. The chromogenic dye was prepared from the water extract of beetroot. Under selected assay conditions, the raw milk turns yellow-orange whereas pasteurized milk remains bright pink; which can be visualized by naked human eyes within two minutes. The developed assay is extremely useful in rural areas of our country where modern instrument facilities are rarely available. The activity of ALP was also evaluated in raw and heat-treated milk using Front-face Fluorescence Spectrophotometer (excitement and emission mode) followed by PCA.

Comparison of molecular techniques for the detection of Toxoplasma gondii in raw bovine milk from small rural properties in Brazil

This study aimed to research Toxoplasma gondii DNA in 102 samples of raw bovine milk from expansion tanks, in small properties located in different cities of the Midwest region of São Paulo, Brazil. For this, polymerase chain reaction (PCR) was performed with the primers TOX4/TOX5 for cPCR (conventional PCR), TgNP1/TgNP2 gene for nested PCR and the Tg18s58F/Tg18s348R for nested PCR. It was possible to detect T. gondii DNA in 18 (17.65 %) milk samples from the 102 tanks, corresponding to 4.90 % for TOX4/TOX5 primers, 12.74 % for TgNP1/TgNP2 gene and 0.98 % for Tg18s58F/Tg18s348R gene. The results showed that the TgNP1 and TgNP2 genes were more efficient to detect T. gondii DNA, and also indicated the importance of raw bovine milk as a source of human infections caused by this protozoan, being a public health problem. It is important to continue studies involving T. gondii from bovine milk considering the need for proper pasteurization, and for better comprehension regarding the epidemiology of this protozoan.

Development of bio-strip based test for ascertain proper milk pasteurization

Alkaline phosphatase (ALP) enzyme is naturally present in raw milk which is used as a prominent indicator to determine proper pasteurization in milk. However, determination of ALP activity in milk either time-consuming or required sophisticated instrument facilities that are uncommon in India's rural dairy or collection centers. Present test is based on the ALP reaction with p-nitrophenyl phosphate to release p-nitrophenol and inorganic phosphate in the presence of water. When p-nitrophenol reacts with a certain chromogen, the strip's colour changes from purple to grey, which may be seen with the naked eye. This strip has a nine-month shelf life at room temperature.

Presence of Brucella spp. in Milk and Dairy Products: A Comprehensive Review and Its Perspectives

Consuming raw milk and milk-based products that have not been produced under strict control conditions can cause brucellosis, a highly contagious zoonotic disease. It is a significant global public health concern, particularly in regions with poor management and limited resources, such as Latin America, North and East Africa, the Middle East, and South and Central Asia. The study aims to summarize the occurrence of human brucellosis linked to milk and milk products and the presence of Brucella species in dairy foods. To achieve this goal, a meta-analysis was conducted on 69 studies ranging from 2001 to 2022, which were categorized into two groups: the incidence of Brucella species in milk and milk products and the prevalence of human brucellosis resulting from the consumption of contaminated milk. The following milk and milk products showed the highest incidence of Brucella species: cow milk (1.86%–81.7%), buffalo milk (10.4%–61.67%), camel milk (0%–24%), goat milk (0%–88.8%), and cheese (0%–39.1%). Consuming unpasteurized milk and milk products has been identified as the leading cause of human brucellosis, with incidence rates varying from 33.9% to 100%. Several human brucellosis cases have been linked to consuming raw milk and cheese in Spain, Israel, and other countries. Various serological techniques are employed to detect Brucella-specific antibodies in milk. The milk ring test (MRT) and enzyme-linked immunoassay (ELISA) are the two most widely utilized methods for detecting these antibodies in milk. Recently developed dual biosensors are a powerful approach for early diagnosis of Brucella from milk. Real-time PCR can rapidly detect organisms, reducing the risk of lab contamination and false positive results. To prevent and control brucellosis, essential steps include proper pasteurization of milk and dairy products, using the milk ring test (MRT) to detect Brucella in individual and bulk milk, immunization, education, and increasing public awareness of the disease. The consumption of raw milk and milk-made products that are not produced under strictly controlled conditions poses a significant risk to human health, mainly due to the high incidence of Brucella contamination. Therefore, ensuring strict control measures in producing milk and milk-made products is crucial to preventing the spread of this disease and safeguarding human health.

Toxoplasma gondii in lactating animals: potential risk to milk consuming population in Khyber Pakhtunkhwa.

Toxoplasma gondii is an intracellular zoonotic protozoan parasite usually infects human and animal worldwide. This study aimed to analyze the sero-prevalence of T. gondii in blood of lactating animals and human living in close proximity and also to detect Toxoplasma DNA in unpasteurized milk of the studied animals. A total of 233 blood and milk samples were collected from lactating animals, and 735 blood samples were taken from humans in District Upper Dir, Khyber Pakhtunkhwa, Pakistan. The blood samples were analyzed through ELISA while the milk samples were analyzed by PCR for the presence of T. gondii DNA. A standard questionnaire was introduced to collect the data from the participants. In animals, the reported sero-prevalence was 32.18% for IgM, 17.16% for IgG, and 6.4% for both IgM and IgG. The reported positivity for T. gondii DNA in milk was 14.44%, 34.8%, 20%, and 26% in sheep, goats, cows, and buffaloes, respectively. In the human blood samples, 9.8% were found positive for IgM and 11.2% for IgG while none of the samples was found positive for both IgM and IgG. Overall sero-prevalence reported in females was significantly higher than the male (p<0.05) poor hygiene condition (p < 0.0001) were the significant risk factors associated with T. gondii infections in animals. In conclusion, T. gondii infection is prevalent in lactating animals and humans using their raw milk in the study area. It is suggested that raw milk should be considered as a vehicle for the transmission of T. gondii to humans. Proper pasteurization of milk is very useful in limiting the transmission of infection. Awareness and control programs should be implemented to prevent the infection.

Zoonotic Importance of Bovine Tuberculosis in Ethiopia: An Overview

Bovine tuberculosis (BTB) is an important zoonotic disease that affects both domestic animals as well as humans in many countries of the world. The disease is caused by Mycobacterium bovis, which is responsible for 10–15% of human tuberculosis cases. BTB poses an occupational health hazard to the cattle owners, butchers, animal attendants, and veterinarians. The source of infection is exogenous and the respiratory tract is considered the chief portal of entry of the organism. The mode of spread of bacteria is aerogenous. BTB is endemic in Ethiopia, and it is mostly transmitted to people through the consumption of unpasteurized contaminated milk. Miliary tubercular lesions, chronic cough, blockages of the airways, alimentary system, or blood vessels, and lymph node enlargement are all symptoms of tuberculosis. Single intradermal or comparative intradermal tuberculin tests are useful delayed-type hypersensitivity tools for diagnosing tuberculosis in live animals. It is also employed in tuberculosis eradication programs and international trade activity. Vaccination of calves with an attenuated BTB strain known as Bacillus of Calmette and Guerin, as well as testing and culling, is significant measures in the prevention and control of BTB in endemic areas like Ethiopia. The proper pasteurization of milk before human consumption is a significant measure to reduce the public health risk posed by BTB.

Effect of water activity on the thermal inactivation kinetics of Salmonella in milk powders

Persistence of Salmonella in milk powders has caused several foodborne outbreaks. The determination of proper pasteurization processing conditions requires an understanding of the thermal inactivation kinetics of Salmonella in milk powders. However, there is a lack of knowledge related to the effects of water activity (aw) and fat content on Salmonella inactivation in milk powder during thermal processing. Two types of milk powders, nonfat dry milk and whole milk powder, with different fat contents (0.62 and 29.46% wt/wt, respectively) were inoculated with a 5-strain cocktail of Salmonella and equilibrated to 3 aw levels (0.10, 0.20, and 0.30) for isothermal treatments at 75, 80, and 85°C to obtain D-values (the time required to achieve a 10-fold reduction of the bacteria at the isothermal treatment temperature) and z-values (the increase in temperature required to achieve a 90% reduction of the decimal reduction time D). Stability tests showed that the inoculation method used in this study provided a high and stable population of Salmonella for thermal inactivation studies. A moisture sorption isotherm was measured to understand the relationship between aw and moisture content of milk powders. The thermal resistance of Salmonella was found to significantly increase as aw decreased, which suggested that a higher temperature or longer processing time would be required at low aw to achieve the desired inactivation of Salmonella. The microbial inactivation kinetics were not significantly different for the 2 milk powders; therefore, data were combined to develop a universal model. A response surface model was compared with a modified Bigelow model. The modified Bigelow model performed well to predict D-values [root mean square error (RMSE) = 1.47 min] and log reductions (RMSE = 0.48 log cfu/g). The modified Bigelow model developed here could be used to estimate D-value as a function of water activity and temperature to design a thermal pasteurization system for milk powders.

Risk and benefits of consuming raw (unpackaged) and pasteurized (packaged) milk

The aim of this review is to overview important literature data on milk and its composition, methodology of quality assurance throughout its processing and preservation, and to compare risks and benefits of consuming raw (unpackaged) and pasteurized (packaged) milk. Milk contamination risks are of various types, including physical contamination (foreign components, such as manure, feed, dust, pieces of broken glass, strands of hair, wood, plastic, or metal chips), chemical impurities (antibiotics, hormones, pesticides, detergents, or heavy metal residues), and microbiological agents (germs and somatic cells). Our study addresses the quality and safety of raw and pasteurized milk consumed by humans. If one considers risks and benefits simultaneously, there are many pros and cons of consuming raw and pasteurized milk. One can conclude that pasteurized milk is more appropriate for consumption as compared to the lower quality raw milk. For manufacturing high quality pasteurized milk, one should implement good hygienic practices, proper pasteurization process, as well as pre and post pasteurization preservation.

Review on Q Fever in Small Ruminants and its Public Health Importance

Q fever is a disease caused by coxiella burnetii which is ubiquitous intracellular bacterial pathogen, with acute and chronic clinical manifestations. This bacterium is able to infect a wide range of animals, but cattle, sheep and goats are the principal reservoirs. Inhalation of contaminated aerosols is the main transmission route for humans. Q fever is a worldwide zoonosis, which may occur in sporadic as well as epidemic forms. Because it is highly infectious for humans, Q fever is an important zoonosis with veterinarian laboraratory workers, farmers and abattoir workers at risk. The spectrum of clinical manifestations in humans and animals are diverse, ranging from seroconversion without any clinical symptoms to fatal consequences. The acute infection in humans manifests as self-limiting febrile illness, pneumonia, or hepatitis, whereas endocarditis is the major manifestation in chronic cases. Infection in domestic animal is usually asymptomatic and remains unrecognized, but it may cause abortion, especially in sheep and goat. In Ethiopia, the existence of antibody against Coxiella burnetii was reported in goats and sheep slaughtered at Addis Ababa abattoir, and its peri-urban .or from milk and urine are the basis of confirmatory diagnosis of C. burnetii infection. Doxycycline and tetracycline is the recommended antibiotic for humans. Cotrimoxazole and rifampin are the drugs of choice for the patients allergic or contradicted to tetracyclines. Oxytetracycline in the last trimester of pregnancy is usually recommended for animals. Control of Q fever in humans is largely dependent upon the control of infection in animals. The risk for transmission can be decreased through attention to proper sanitation when dealing with parturient animals and ensuring proper pasteurization of milk products.

Shelf life of donkey milk subjected to different treatment and storage conditions

The aim of this study was to investigate the effects of different treatment conditions on microbiological indicators of donkey milk hygiene and their evolution during shelf life at 4 and 12°C from 3 to 30d, simulating a farm-scale pasteurization and packing system. Four treatment conditions were tested: no treatment (raw milk), pasteurization (65°C × 30 min), high-pressure processing (HPP), and pasteurization plus HPP. The microbiological quality of the raw donkey milk investigated was not optimal; our results highlight the importance of raw milk management with the need for animal hygiene management and good dairy farming practices on donkey farms to improve handling procedures. The raw milk treated with HPP alone showed visible alterations with flocks, making the milk unfit for sale. The microbiological risk posed by consumption of raw donkey milk was significantly reduced by heat treatment but farm-scale packing systems cannot guarantee an extended shelf life. In contrast, the pasteurization plus HPP treatment was the most effective method to maintain microbiological milk quality. Microflora growth had little effect on pH in donkey milk: pH values were significantly different only between raw milk and pasteurized and pasteurized plus HPP milk stored at 12°C for 3d. Alkaline phosphatase activity and furosine could be used as indicators of proper pasteurization and thermal processing in donkey milk. Moreover, the presence and growth of Bacillus cereus in the case of thermal abuse hamper the wide-scale marketing of donkey milk due to the potential consequences for sensitive consumers and therefore further tests with time/temperature/high-pressure protocols associated with B. cereus are needed. Finally, our study shows that an HPP treatment of pasteurized milk after packing extends the shelf life of donkey milk and assures its microbial criteria up to 30d if properly stored at 4°C until opening; therefore, combined heat treatment and storage strategies are recommended to enhance the shelf life of donkey milk.

Alkaline phosphatase activity and microbiological quality of heat-treated goat milk and cheeses

The importance of goat milk and products of goat milk origin in human nutrition has increased in recent years. To provide a high quality and safety of this kind of food and to avoid a risk for public health, the criteria referring to microbiological quality of raw milk and final products, as well as to heat treatment have to be met. In the present study the alkaline phosphatase activity (ALP) in pasteurized goat milk and cheeses was determined. A hygiene quality and a presence of selected bacteria in goat milk products were also tested. The samples of milk (n=100) and cheese (n=105) originated from Polish dairies were analyzed. Ninety seven percent of milk and 94.3% of cheese samples showed ALP activity below 350mU/L and 10mU/g, respectively. The absence of Salmonella spp., Listeria monocytogenes and coagulase-positive staphylocci was observed in all samples tested, whereas in some of them Escherichia coli and Enterobacteriaceae were identified. The present study showed that pasteurized and UHT goat milk as well as goat cheeses from pasteurized milk were safe for consumers in terms of the absence of bacterial pathogens if proper pasteurization of raw milk is applied.

Alkaline phosphatase activity in cheese as a tracer for cheese milk pasteurization

Alkaline phosphatase (ALP) activity is used throughout the world as a marker for the proper pasteurization of milk, to guarantee its hygienic safety. The Standard ISO 11816-2/IDF 155-2 describes the analysis of ALP in cheese. However, the method has been questioned in the past because there have sometimes been ambiguous results. The critical operations of the analytical procedure are more precisely defined and a zonal cheese sampling adopted. ALP inactivation is firstly evaluated in the relevant steps of controlled cheese makings of hard (Emmental), semi-hard (Raschera) and soft (Chaource) cheeses. Application of the improved procedure in over 700 samples of typical cheeses from France, Italy and Switzerland proved the applicability of the method. Based on this large study, a limit for ALP activity in cheese from pasteurized milk is proposed at 10 mU/g.

Prevalence of Campylobacter species in milk and milk products, their virulence gene profile and anti-bio gram.

Aim:During the last decades, number of food poisoning cases due to Campylobacter occurred, immensely. After poultry, raw milk acts as a second main source of Campylobacter. Therefore, the present study was undertaken to detect the prevalence of Campylobacters in milk and milk products and to know the antibiotic sensitivity and virulence gene profile of Campylobacter spp. in Anand city, Gujarat, India.Material and Methods:A total of 240 samples (85 buffalo milk, 65 cow milk, 30 cheese, 30 ice-cream and 30 paneer) were collected from the different collection points in Anand city. The samples were processed by microbiological culture method, and presumptive isolates were further confirmed by genus and species-specific polymerase chain reaction using previously reported primer. The isolates were further subjected to antibiotic susceptibility assay and virulence gene detection.Result:Campylobacter species were detected in 7 (2.91%) raw milk samples whereas none of the milk product was positive. All the isolate identified were Campylobacter jejuni. Most of the isolates showed resistance against nalidixic acid, ciprofloxacin, and tetracyclin. All the isolates have three virulence genes cadF, cdtB and flgR whereas only one isolate was positive for iamA gene and 6 isolates were positive for fla gene.Conclusion:The presence of Campylobacter in raw milk indicates that raw milk consumption is hazardous for human being and proper pasteurization of milk and adaptation of hygienic condition will be necessary to protect the consumer from this zoonotic pathogen.

Responding to Bioterror Concerns by Increasing Milk Pasteurization Temperature Would Increase Estimated Annual Deaths from Listeriosis

In a 2005 analysis of a potential bioterror attack on the food supply involving a botulinum toxin release into the milk supply, the authors recommended adopting a toxin inactivation step during milk processing. In response, some dairy processors increased the times and temperatures of pasteurization well above the legal minimum for high temperature, short time pasteurization (72 °C for 15 s), with unknown implications for public health. The present study was conducted to determine whether an increase in high temperature, short time pasteurization temperature would affect the growth of Listeria monocytogenes, a potentially lethal foodborne pathogen normally eliminated with proper pasteurization but of concern when milk is contaminated postpasteurization. L. monocytogenes growth during refrigerated storage was higher in milk pasteurized at 82 °C than in milk pasteurized at 72 °C. Specifically, the time lag before exponential growth was decreased and the maximum population density was increased. The public health impact of this change in pasteurization was evaluated using a quantitative microbial risk assessment of deaths from listeriosis attributable to consumption of pasteurized fluid milk that was contaminated postprocessing. Conservative estimates of the effect of pasteurizing all fluid milk at 82 °C rather than 72 °C are that annual listeriosis deaths from consumption of this milk would increase from 18 to 670, a 38-fold increase (8.7- to 96-fold increase, 5th and 95th percentiles). These results exemplify a situation in which response to a rare bioterror threat may have the unintended consequence of putting the public at increased risk of a known, yet severe harm and illustrate the need for a paradigm shift toward multioutcome risk benefit analyses when proposing changes to established food safety practices.

Brucellosis - An Infectious Re-Emerging Bacterial Zoonosis of Global Importance

Brucellosis, a highly infectious, re-emerging bacterial anthropozoonotic disease of global significance, is important public health and economic point of view. The disease is found worldwide but it is well controlled in most developed countries. Brucellosis, caused by several species of Brucella, is a sub-acute or chronic disease which may affect many species of animals. In cattle, sheep, goats, other ruminants and pigs, the initial phase following infection is often not apparent. The disease in animals causes tremendous economic losses. The disease is usually transmitted from infected animals to humans through contact with animals or consumption of their products mostly dairy products made from unpasteurized milk. It is also an occupational hazard to persons who are engaged in handling of the infected animals and their products. Laboratory investigation is imperative to confirm an unequivocal diagnosis of brucellosis. Since humans acquire the infection from animals, it is emphasized to control the disease in animals. Proper pasteurization of milk and other dairy products and use of protective wears are important safety measures in those areas where brucellosis is endemic. In recent years, the global epidemiology of the disease has not altered drastically. New strains of Brucella may emerge and existing types adapt to changing social and agricultural practices. Hence, further epidemiological studies on the identification of new strains of the Brucella should be conducted.

Thermal inactivation kinetics of alkaline phosphatase in equine milk

Alkaline phosphatase (ALP) is widely used as an indicator of proper pasteurization in bovine milk. Due to interest in the use of equine ALP as a time/temperature integrator (TTI) for evaluation of the efficacy of thermal processing of equine milk, its inactivation kinetics were evaluated in whole and skimmed equine milk. Experimentally determined decimal reduction times showed that equine ALP is more readily inactivated in equine milk than its bovine counterpart. Thus, considering the required 6 D reduction of pathogens and the rather low enzyme level present in equine milk, equine ALP will not be suitable as indicator for correct pasteurization of equine milk under the conditions currently used in the reference method for the determination of ALP in milk-based products.

Evaluation of a Chemiluminescence Method for Measuring Alkaline Phosphatase Activity in WholeMilk of Multiple Species and Bovine Dairy Drinks: Interlaboratory Study

Alkaline phosphatase (ALP) is a ubiquitous enzyme in milk with time-temperature destruction similar to that of certain pathogens destroyed in pasteurization. Measurement of ALP to indicate proper pasteurization is a common practice. Recently the public health level for ALP was decreased to 350 mU/L, a level below the sensitivity of older colorimetric ALP methods. This study was conducted within the structure of the International Dairy Federation and the International Organization for Standardization to evaluate the reproducibility of the chemiluminescence method (Charm PasLite) for ALP at 50, 100, 350, and 500 mU/L in whole milk of multiple species to meet new regulations in the United States and proposed regulations in the European Union (EU). Fifteen laboratories from 8 countries evaluated bovine, goat, sheep, and buffalo milk, bovine skim milk, 20% fat cream, and 2% fat chocolate milk. At ALP levels of 350 and 500 mU/L, the average relative standard deviation for repeatability (RSDr) was 7.5%, and the average relative standard deviation of reproducibility was (RSDR) 15%. For ALP at 100 and 50 mU/L, the average RSDr values were 10.5 and 12.6%, respectively, and the average RSDR values were 18 and 25%, respectively. The limit of detection was 20 mU/L. Results are comparable to those obtained with other enzymatic photo-activated system methods such as the fluorometric method. Results indicate that the method is suitable for measuring ALP in the milk of multiple species and in dairy drinks at U.S. and proposed EU levels.

Collaborative Evaluation of a Fluorometric Method for Measuring Alkaline Phosphatase Activity in Cow's, Sheep's, and Goat's Milk

Pasteurization of raw milk was introduced to extend product shelf life and destroy pathogens. The measurement of alkaline phosphatase (ALP) activity has been used as an indicator of proper pasteurization in dairy products for more than 65 years. This study was undertaken to evaluate six different fluid dairy products at lower phosphatase levels than previously verified using the Fluorophos Test System, a sensitive and precise method for ALP activity detection. Thirteen laboratories participated in this collaborative, international study to evaluate the fluorometric test at 20, 40, 100, 350, and 500 mU/liter and extend the scope of the method to include milk from not only cows but also goats and sheep. Initially, the statutory level of ALP measured fluorometrically was set to equivalent levels of colorimetric test standards (500 mU/liter). The European Union recently announced its intention of lowering the legal limit from 500 to 350 mU/liter and, in addition, setting a target value of 100 mU/liter, which if exceeded would trigger an investigation into the pasteurizer plant performance. At 500 mU/liter of ALP, this trial generated relative standard deviation of repeatability values of 6.48, 5.69, and 1.74% and relative standard deviation of reproducibility values of 14.66, 13.30, and 5.33% for all cow's, sheep's, and goat's milk samples, respectively. Data from this study are comparable to data from previous studies and indicate the suitability of the Fluorophos Test System method for measuring ALP activity in milk from cows, sheep, and goats not only at the current European statutory level of 500 mU/liter but also at much lower levels.

An alternative heat treatment for milk pasteurization in Cameroon

In order to determine a suitable temperature and time combination for the proper pasteurization of milk under conditions in Cameroon, the destructive effects of heat on the peroxidase and micro‐organisms in local milk were studied. In the first step, fresh milk samples were heated at temperatures of 64–100°C for 1 min. Peroxidase was found to be sensitive to heat treatment at temperatures of 74–76°C and completely destroyed above 78°C. In the second step, fresh milk samples were heated to 74°C and held at that temperature for 15 s, 5 min, 10 min, 15 min or 20 min; microbiological analyses revealed that survival rates were 56.7, 1.5, 0.2, 0.06 and 0.05%, respectively. Peroxidase was completely destroyed after 10 min at this temperature. In terms of microbial quality, there were no significant differences (P &lt; 0.001) between holding times of 10, 15 and 20 min. A heat treatment of 74°C for 10 min yielded milk free of peroxidase and with &lt; 10 000 cfu/mL. It is recommended that raw milk be given at least this treatment to ensure safe milk supplies in Cameroon.