Dairy Food Products Research Articles

Estimation of genetic parameters and detection of quantitative trait loci for metabolites in Danish Holstein milk

Small components and metabolites in milk are significant for the utilization of milk, not only in dairy food production but also as disease predictors in dairy cattle. This study focused on estimation of genetic parameters and detection of quantitative trait loci for metabolites in bovine milk. For this purpose, milk samples were collected in mid lactation from 371 Danish Holstein cows in first to third parity. A total of 31 metabolites were detected and identified in bovine milk by using 1H nuclear magnetic resonance (NMR) spectroscopy. Cows were genotyped using a bovine high-density single nucleotide polymorphism (SNP) chip. Based on the SNP data, a genomic relationship matrix was calculated and used as a random factor in a model together with 2 fixed factors (herd and lactation stage) to estimate the heritability and breeding value for individual metabolites in the milk. Heritability was in the range of 0 for lactic acid to >0.8 for orotic acid and β-hydroxybutyrate. A single SNP association analysis revealed 7 genome-wide significant quantitative trait loci [malonate: Bos taurus autosome (BTA)2 and BTA7; galactose-1-phosphate: BTA2; cis-aconitate: BTA11; urea: BTA12; carnitine: BTA25; and glycerophosphocholine: BTA25]. These results demonstrate that selection for metabolites in bovine milk may be possible.

Anticancer Effect in HL-60 Human Leukemia Cells and Other Helath-Beneficial Functions of Cheese

With regard to the aim of cancer prevention and/or treatment, a considerable number of basic studies have indicated that dairy and other plant-originated natural food products may possess anticancer activity. On the growth of human leukemia cells, for example, enzymatically digested skim milk or fermented milk cultured with various bacteria can exhibit differential suppressive activities. Our research team has previously revealed that highly ripened cheese was capable of demonstrating strong growth inhibition and induction of apoptotic DNA damage on HL-60 human promyelocyticleukemia cells. In this short review, the available information concerning potent anticancer effects of cheese was summarized. From the stand point of Food Science, functional implications for cancer prevention as well as multifaceted function of cheese are discussed.

Association between Dairy Food Consumption and Risk of Myocardial Infarction in Women Differs by Type of Dairy Food

The relation between dairy foods, particularly specific foods, and risk of cardiovascular disease (CVD) remains unclear. We examined the association between total, as well as specific, dairy food intakes and incidence of myocardial infarction (MI) in a prospective population-based cohort. We followed 33,636 women (aged 48–83 y), free from CVD, cancer, and diabetes at baseline (1997), in the Swedish Mammography Cohort. Consumption of milk, cultured milk/yogurt, cheese, cream, crème fraiche, and butter was obtained from a validated self-administered FFQ at baseline. We used Cox proportional hazards regression models to estimate HRs and 95% CIs, adjusted for relevant CVD risk factors. MI incidence was ascertained from national registries. Over 11.6 y of follow-up, we ascertained 1392 cases of MI. When the highest quintile was compared with the lowest quintile, total dairy food intake was inversely associated with MI risk [multivariable adjusted HR: 0.77 (95% CI: 0.63, 0.95)]. Among specific dairy food products, total cheese was inversely associated [HR: 0.74 (95% CI: 0.60, 0.91)] and butter used on bread but not on cooking was positively associated [HR: 1.34 (95% CI: 1.02, 1.75)] with MI risk. Other specific dairy food products were not significantly associated with MI risk. No differences were observed between consumption of specific low-fat and high-fat dairy foods, expressed as either absolute intakes or intakes relative to the total, and MI risk. Failure to consider dairy foods as a heterogeneous group in future studies could hamper important insights of relevance for the development of dietary guidelines.

Determination of Aflatoxin Levels in Some Dairy Food Products and Dry Nuts Consumed in Saudi Arabia

Three hundred and ninety-three samples of dairy products (124 samples of white cheese, 61 samples of cream cheese, 76 samples of Kashar cheese, and 132 samples of butter), 91 samples of cashew nut and 97 macademia nut marketed in Eastern Province, Saudi Arabia during September 2010-September 2011, were analyzed for aflatoxin M1 (AFM1), total aflatoxin and AFB1 by microtitre plate enzyme linked immunosorband assay (ELISA) The incidence of AFM1 contamination in dairy products analyzed was 82%. Total aflatoxin contamination was determined in 84 (92.3%) of 91 cashew nut and in 88 (90.7%) of 97 macademia nut whereas total aflatoxin contamination was not detected in 3 (3.2%) of 91 cashew nut samples and in 12 of 97 macademia nut samples. AFB1 was found in 84 (92.3%) of 91 cashew nut and in 83 (85.5%) of 97 samples of macademia nut samples. AFM1 levels in 3 (2.4%) white cheese, 4 (3.0%) of butter, 2 (3.2%) in cream cheese and 5 (6.5%) of Kashar cheese samples were found higher than the maximum acceptable levels as set by European Union.Continuous surveillance program may be warranted to monitor regularly the occurrence of aflatoxins in foodstuffs.

Occurrence and Antimicrobial Susceptibility of Listeria monocytogenes Isolated from Brined White Cheese in Jordan

Listeria monocytogenes is a serious foodborne pathogen that has been isolated from different dairy food products. Several foodborne outbreaks of listeriosis have been associated with consumption of cheese. The aims of this study were to determine the occurrence of L. monocytogenes and Listeria spp. in brined white cheese (BWC) sold in Jordan, and to determine the susceptibility of isolated L. monocytogenes to antimicrobials. Three hundred and fifty samples of 5 different types of BWC (akkawi, boiled, halloumi, pasteurized, and shellal) were collected from a local market in Jordan. The ISO (11290-1) procedure was followed for isolation and identification of Listeria spp. from cheese samples and a polymerase chain reaction (PCR) technique was used for confirmation of L. monocytogenes isolates. The VITEK2 automated system was used for testing antimicrobial susceptibility of L. monocytogenes isolates. The overall prevalence of Listeria spp. in cheese sample was 27.1%. L. monocytogenes was isolated from 39 (11.1%) samples. Other isolated species were L. grayi (6.9%), L. innocua (2%), L. ivanovii (4%), L. seeligeri (2%), and L. welshimeri (0.3%). The pH values and salt concentrations of L. monocytogenes positive cheese samples ranged from 5.10 to 6.32 and 5.64 to 13.16, respectively. L. monocytogenes isolates were sensitive or intermediate susceptible to imipenem, gentamicin, linezolid, teicoplanin, vancomycin, fusidic acid, trimethoprim/sulfamethoxazole, benzylpenicillin, ciprofloxacin, erythromycin, tetracycline, and rifampicin, but resistant to fosfomycin, oxacillin, and clindamycin.

Functional foods as carriers for SYNBIO®, a probiotic bacteria combination

The popularity of functional foods continues to increase as consumers desire flavorful foods that will fulfil their health needs. Among these foods, probiotics may exert positive effects on the composition of gut microbiota and overall health. However, in order to be beneficial, the bacterial cultures have to remain live and active at the time of consumption. The aim of this study was to develop new probiotic food products, such as seasoned cheeses, salami, chocolate and ice-cream with a final probiotic concentration of approximately 109CFU/daily dose of Lactobacillus rhamnosus IMC 501® and Lactobacillus paracasei IMC 502® mixed 1:1 (SYNBIO®). The survival and viability of probiotics were determined during the foods shelf-life. The values of viable probiotic bacteria of all dairy and non-dairy foods were between 107 and 109CFU/g of food at the end of the shelf-life and for some of them the values were maintained even after the expiry date. Based on the results of the current study, all the dairy (“Caciotta” cheese, “Pecorino” cheese, “Büscion” Swiss cheese and “Fiordilatte” ice-cream) and non-dairy (“Ciauscolo” salami, Larded salami, Swiss small salami, milk chocolate, dark chocolate, organic jam and chocolate mousse) food products studied would be excellent vehicles to deliver the probiotic health effects because of the high viability of probiotics during the shelf-life of foods and in some cases even after their expiry date.

Influence of Certain Pulsed Electric Field Conditions on the Growth of Lactobacillus acidophilus LA-K

Pulsed Electric Field (PEF) processing involves the application of pulses of electricity, for less than one second to fluid products placed between two electrodes. Lactobacillus acidophilus is an important probiotic bacterium used for the production of fermented dairy foods. The objective was to study the influence of electric pulse period, electric field strength, and electric pulse width on the growth of Lactobacillus acidophilus LA-K. Lactobacillus acidophilus LA-K, suspended in sterile peptone water was treated using an OSU-4 PEF processor. The treatments were pulse periods of 10,000, 20,000 and 30,000 μs electric field strength of 5, 15 and 25 kV/cm, and pulse widths of 3, 6 and 9 μs. Growth was determined hourly for 16 hours of anaerobic incubation at 37°C. Pulse period had a significant (p=0.0017) influence on the growth. There were no significant differences among the control, 30,000 μs and 20,000 μs. The growth of Lactobacillus acidophilus subjected to the pulse period of 10,000 μs was significantly lower than the growth of the control, and the growth when subjected to 30,000 μs. Electric field strength had a significant (p<0.0001) influence on the growth. Growth subjected to 15 and 25 kV/cm was significantly lower than the control and 5 kV/cm. There were no significant differences between the control and 5 kV/cm. There were no significant differences between the growth, when Lactobacillus acidophilus was subjected to 15 and 25 kV/cm. Bipolar pulse width effect had a significant (p<0.0001) influence on the growth. Growth of the control was significantly higher than the growth of Lactobacillus acidophilus subjected at any of the bipolar pulse widths studied. There were no significant differences in growth among the three different bipolar pulse widths. Electric field strength significantly influenced growth of Lactobacillus acidophilus LA-K. Bipolar pulse width and pulse period slowed log stage growth of Lactobacillus acidophilus LA-K. Slower growth of adjunct bacteria can sometimes be good in the manufacture of cultured dairy foods, as it results in controlled release of bacterial enzymes for improved flavor and texture development.

From the Editors—Animal selection: The genomics revolution

The rapid improvements in high-throughput single nucleotide polymorphism (SNP) genotyping technologies, ever-denser SNP arrays accompanied by reduced costs for genotyping and for sequencing, open the possibility of using genomic information in livestock selection. The industry is thus facing the new paradigm of “genomic selection,” in which genomic information may reduce costs and accelerate genetic gain by reducing generation intervals. Genetic markers, or SNP, are highly abundant in the genome, and highthroughput molecular technologies allow the inheritance of hundreds of thousands of such markers to be traced through generations for currently less than US $200 per animal. Even if the mutations themselves do not directly affect the phenotype, they can track for the variability of causal mutations in their vicinity. By summing the effects assigned to each SNP, we can create a numeric value (genomic breeding value) that allows the genetic potential of a breeding animal to be assessed. This is an enormously valuable tool for choosing breeding animals as parents of the next generation. In addition, genomic selection may allow the identifi cation of superior individuals for traits not currently considered in animal breeding plans because of technical diffi culties. For example, the fatty acid composition of dairy and beef food products, increased disease resistance (and thus increased animal welfare), and decreased methane emissions in cattle help to address the needs of consumers and society for sustainable and cost-effective food production. The animal breeding industry is currently adapting selection procedures in each species to include this innovative tool. This is causing a worldwide restructuring of the animal breeding industry. As an example in dairy cattle, large international consortia are being formed to develop joint precompetitive research and tools. For similar reasons, in the future, genomic selection might help close the gap between countries with greater and lesser production. The scope of this issue of Animal Frontiers is to provide a worldwide overview and various perspectives on intermediate-term scenarios resulting from the application of genomic tools in different livestock species. Genomic selection has already had a huge impact in genetic selectionrelated industries. Such industries have had the same structure for at least 3 decades. Subsequent to the research conducted by animal geneticists in the 1960s and 1970s, mainly by Charles Henderson and his group, animal selection remained the same for many years. Of course, new traits were included and new species were selected in addition to dairy cattle, but the industry structure generally remained the same. During these years, genetic selection also incorporated new computer technologies and animal reproduction discoveries to improve the identifi cation of superior animals. The genomic revolution created large changes in this structure. New actors appeared on the scene. In this issue of Animal Frontiers, relevant technicians and scientists were invited to focus on the impact of the genomic revolution on the genetics industry and to forecast future developments.

Reducing Meat Consumption in Today’s Consumer Society: Questioning the Citizen-Consumer Gap

Our growing demand for meat and dairy food products is unsustainable. It is hard to imagine that this global issue can be solved solely by more efficient technologies. Lowering our meat consumption seems inescapable. Yet, the question is whether modern consumers can be considered as reliable allies to achieve this shift in meat consumption pattern. Is there not a yawning gap between our responsible intentions as citizens and our hedonic desires as consumers? We will argue that consumers can and should be considered as partners that must be involved in realizing new ways of protein consumption that contribute to a more sustainable world. In particular the large food consumer group of flexitarians offer promising opportunities for transforming our meat consumption patterns. We propose a pragmatic approach that explicitly goes beyond the standard suggestion of persuasion strategies and suggests different routes of change, coined sustainability by stealth, moderate involvement, and cultural change respectively. The recognition of more routes of change to a more plant-based diet implies that the ethical debate on meat should not only associate consumer change with rational persuasion strategies and food citizens that instantiate “strong” sustainable consumption. Such a focus narrows the debate on sustainable protein consumption and easily results in disappointment about consumers’ participation. A more wide-ranging concept of ethical consumption can leave the negative verdict behind that consumers are mainly an obstacle for sustainability and lead to a more optimistic view on modern consumers as allies and agents of change.

DIETARY PREDICTORS OF HELICOBACTER PYLORI SEROPREVALENCE IN MEXICAN ADULT POPULATION

Background and Aims: H. pylori (Hp) infection is the main etiological factor for gastritis and peptic ulcer. Prevalence of infection is one of highest around the world, and it varies in different societies and geographical locations. This variability is attributed to factors such as socioeconomic status, life style, family density and other factors such as eating habits. However, factors influencing the risk of acquisition of Hp infection are not well established. The objective of this study was to identify the dietary predictors of Hp seroprevalence in adult Mexican population. Methods: From January 2002 to December 2004 a cross-sectional study was carried out in Mexico City. A total of 349 ambulatory patients were recruited from 7 tertiary hospitals. From each participant, who had not received any previous anti-Hp treatment, Hp strains were isolated from an antral and corpus biopsy. Food and nutrients intake was estimated by a food frequency questionnaire. Results: A significant reduction in Hp seroprevalence was observed among those who reported high vs low consumption of milk (OR=0.52, 95%CI:0.31-0.89), Oaxaca cheese (OR=0.44, 95%CI:0.26-0.76), and olive oil (OR=0.49, 95%CI:0.28-0.83), adjusted respectively by age, gender and crowding during childhood. Moreover, we can observed a significant protective effect between high vs low intake of calcium (OR=0.49, 95%CI:0.29-0.85) and fatty acids including butyric acid (OR=0.48, 95%CI:0.25-0.93), caproic acid (OR=0.55, 95%CI:0.32-0.94), capric acid (OR=0.57, 95%CI:0.33-0.98), and lauric acid (OR=0.49, 95%CI:0.29-0.85). Inversely, a significant increase in Hp seroprevalence was observed between high vs low consumption of pork stew (OR=1.72, 95%CI:1.01-2.93), cauliflower (OR=1.83, 95%CI:1.07-2.93), broccoli (OR=1.73, 95%CI:1.01-2.95) and Tomato salsa (OR=1.86, 95%CI:1.09-3.18) Conclusions: This study suggests that consumption of fatty acids and dairy products may have a protective effect against H pylori infection. Additional analytical studies are needed to determine whether consumption of fatty acids and dairy food products can prevent H pylori infection.

Pendrin mediates uptake of perchlorate in a mammalian in vitro system

Perchlorate is a known endocrine disruptor present in groundwater, vegetables and dairy food products in many regions of the United States. It interferes with the uptake of iodide into the thyrocyte by the sodium–iodide symporter at the basolateral surface, thus potentially disrupting the synthesis of thyroid hormone. Because transport of iodide from the thyroid follicular cells to the follicular lumen is mediated by the protein pendrin at the apical surface, we hypothesized that perchlorate may also interact with this protein. Therefore, HeLa cells were transfected with the human SLC26A4 gene, which encodes pendrin, to generate an in vitro mammalian system expressing the recombinant pendrin protein (HeLa-PDS). The HeLa-PDS cells, along with untransfected cells, were then cultured in presence of iodide and/or perchlorate. Intracellular levels of these two chemicals were measured by ion chromatography tandem mass spectrometry. Results from this study show that iodide and perchlorate uptake increases significantly in HeLa-PDS cells as compared to untransfected cells. Thus, recombinant HeLa cells expressing pendrin protein accumulate iodide and perchlorate intracellularly, indicating that pendrin is involved in the uptake of perchlorate. Additional results from this study suggest that iodide and perchlorate competitively inhibit each other for uptake by pendrin. The ability of perchlorate to compete with iodide for uptake by both basal and apical transporters may increase the potential of perturbation of thyroid homeostasis and therefore the estimated risk posed to susceptible human populations.

Microfluidics for food, agriculture and biosystems industries

Microfluidics, a rapidly emerging enabling technology has the potential to revolutionize food, agriculture and biosystems industries. Examples of potential applications of microfluidics in food industry include nano-particle encapsulation of fish oil, monitoring pathogens and toxins in food and water supplies, micro-nano-filtration for improving food quality, detection of antibiotics in dairy food products, and generation of novel food structures. In addition, microfluidics enables applications in agriculture and animal sciences such as nutrients monitoring and plant cells sorting for improving crop quality and production, effective delivery of biopesticides, simplified in vitro fertilization for animal breeding, animal health monitoring, vaccination and therapeutics. Lastly, microfluidics provides new approaches for bioenergy research. This paper synthesizes information of selected microfluidics-based applications for food, agriculture and biosystems industries.

Metagenomic libraries from fermented dairy food products as a novel tool to improve food quality and safety

Metagenomic libraries from fermented dairy food products as a novel tool to improve food quality and safety

Identification of tetracycline‐ and erythromycin‐resistant Gram‐positive cocci within the fermenting microflora of an Italian dairy food product

Microbiological and molecular analysis of antibiotic resistance in Gram-positive cocci derived from the Italian PDO (Protected Designation of Origin) dairy food product Mozzarella di Bufala Campana. One hundred and seven coccal colonies were assigned to Enterococcus faecalis, Lactococcus lactis and Streptococcus bovis genera by ARDRA analysis (amplified ribosomal DNA restriction analysis). Among them, 16 Ent. faecalis, 26 L. lactis and 39 Strep. bovis displayed high minimum inhibitory concentration (MIC) values for tetracycline, while 17 L. lactis showed high MIC values for both tetracycline and erythromycin. Strain typing and molecular analysis of the phenotypically resistant isolates demonstrated the presence of the tet(M) gene in the tetracycline-resistant strains and of tet(S) and erm(B) in the double-resistant strains. Southern blot analysis revealed plasmid localization of L. lactis tet(M), as well as of the erm(B) and tet(S) genes. Genetic linkage of erm(B) and tet(S) was also demonstrated by PCR amplification. Conjugation experiments demonstrated horizontal transfer to Ent. faecalis strain JH2-2 only for the plasmid-borne L. lactis tet(M) gene. We characterized tetracycline-and erythromycin-resistance genes in coccal species, representing the fermenting microflora of a typical Italian dairy product. These results are of particular relevance from the food safety viewpoint, especially in the light of the potential risk of horizontal transfer of antibiotic-resistance genes among foodborne commensal bacteria.

The global food crisis: an Australian dairy industry perspective.

This paper seeks to shed further light on the factors contributing to the emerging global food crisis by examining the reasons for an unusual downturn in dairy food production in Australia, from where 11% of the world trade in dairy foods originates.

Identification of Tetracycline and Erythromycin Resistant Gram-positive Cocci within the fermenting microflora of an Italian Dairy Food Product

Identification of Tetracycline and Erythromycin Resistant Gram-positive Cocci within the fermenting microflora of an Italian Dairy Food Product

Inverse association between dairy intake and hypertension: the Rotterdam Study

Background: Little is known about the effect of different types of dairy food products on the development of hypertension.Objective: The objective was to determine whether the incidence of hypertension in older Dutch subjects is associated with intake of dairy products.Design: We examined the relation between dairy intake and incident hypertension in 2245 participants of the Rotterdam Study aged ≥55 y with complete dietary and blood pressure data, who were free of hypertension at baseline (1990–1993). Blood pressure was reexamined in 1993–1995 and in 1997–1999. Hazard ratios (HRs) with 95% CIs for 2- and 6-y incidence of hypertension were obtained in quartiles of energy-adjusted dairy intake, with adjustment for age, sex, BMI, smoking, educational level, dietary factors, and intake of alcohol and total energy.Results: Risk of hypertension after 2 y of follow-up (664 incident cases) was inversely associated with dairy product intake. After adjustment for confounders, HRs (95% CIs) were 1.00, 0.82 (0.67, 1.02), 0.67 (0.54, 0.84), and 0.76 (0.61, 0.95) in consecutive quartiles of total dairy product intake (P for trend = 0.008). Corresponding HRs for low-fat dairy products were 1.00, 0.75 (0.60, 0.92), 0.77 (0.63, 0.96), and 0.69 (0.56, 0.86) (P for trend = 0.003). Analysis of specific types of dairy products showed an inverse association with milk and milk products (P for trend = 0.07) and no association with high-fat dairy or cheese (P > 0.6). After 6 y of follow-up (984 incident cases), the associations with hypertension were attenuated to risk reductions of ≈20% for both total and low-fat dairy products between the extreme quartiles of intake (P for trend = 0.07 and 0.09, respectively).Conclusion: Intake of low-fat dairy products may contribute to the prevention of hypertension at an older age.

EVALUATION OF COMMERCIAL PREBIOTIC PRODUCTS ON THE GROWTH OF SELECTED PROBIOTIC BACTERIA STRAINS

The commercial prebiotic in cereal- based products with bovine colostrum, namely Germa-Fit® and Extra-Fit® as culture media for the growth of selected probiotic lactic acid strains (grown separately): L.gasseria and L.rhamnosus were cultured in MRS (control) and commercial prebiotic products. The media were fermented for 48h at 37oC and analysed for viable cell count and changes in pH values. In Germa-Fit® medium, both probiotic lactic acid strains were attained the highest population (9.6 cfu/ml) after 16h of fermentation time (P≤0.05). With the addition of lactose at 0.5, 1.0 and 1.5% the viability of L.gasseria was improved by approximately 2.1, 2.3 and 1.7 log10 cycles respectively, compared to 3.0, 2.3 and 2.5 for L.rhamnosus after 12h of fermentation time. The effect of Extra-Fit® medium was more positive for growth L.gasseria than that of L.rhamnosus after 8-24h of inoculation time. Generally, Germa-Fit® medium in the presence lactose exhibited the highest growth for both prebiotic strains compared to Extra-Fit® and MRS media. The changes in pH of commercial media were in the optimal pH range (4.5-4.4) for growth of lactic acid bacteria. Therefore, this study suggested that the feasibility use of commercial prebiotic products based- cereal with bovine colostrum in the place the widely used MRS for culture media of probiotic lactic acid bacteria to developing new synbiotic functional fermented dairy food products.

Streptococcus thermophilus produces exopolysaccharides including hyaluronic acid

Hyaluronic acid (HA) is an important material for medical, cosmetic and food applications. HA is obtained commercially from rooster combs and the fermentation of streptococci. However, the safety problems such as hyaluronidase or exotoxin contamination remain controversial. To reduce the risk of hyaluronidase or exotoxin contamination, we attempted to isolate strains of Streptococcus thermophilus with high productivity of useful exopolysaccharides (EPSs) including HA from traditional dairy food products. Forty-six S. thermophilus strains were isolated from dairy food products, and examined of their HA production using a HA binding protein method. According to the results, six S. thermophilus strains produced EPSs including HA. S. thermophilus YIT 2084 had a markedly high HA productivity (approximately 8 mg/l). We focused on the high-molecular-mass fraction of EPS (2000 kDa) from S. thermophilus YIT 2084. By using high-performance liquid chromatography, it was found that a high-molecular-mass fraction of EPS included N-acetylglucosamine (54.4%) and glucuronic acid (45.6%), which are components of HA. Furthermore, 13C-nuclear magnetic resonance spectroscopy showed that the spectra of the high-molecular-mass fraction corresponded well to those of commercial HA. Here, we described for the first time that S. thermophilus, which is a generally recognized safe bacterium, produces HA. The novel HA-producing bacterium S thermophilus YIT 2084 has great potential for applications in the medical, cosmetic and food fields, although its culture conditions remain to be improved.

Fate of lysostaphin in milk from individual cows through pasteurization and cheesemaking

Transgenic cows secreting over 3μg of lysostaphin/ mL of milk are protected against mastitis caused by Staphylococcus aureus, but it is unknown if active lysostaphin persists through dairy processing procedures or affects the production of fermented dairy foods. The objective of this study was to determine the fate of lysostaphin as milk was pasteurized and then processed into cheese. Raw milk from transgenic cows was heat treated at 63°C for 30min, 72°C for 15s (high temperature, short time), or 140°C for 2s (UHT). Portions of the high temperature, short-time milk were manufactured into semi-hard cheeses. Aliquots taken at each processing step were assayed to determine the quantity (ELISA) and activity (ability to inhibit S. aureus growth) of lysostaphin. Results indicated that most of the lysostaphin was present in the aqueous portion of the milk and was not affected by pasteurization, although UHT treatment reduced enzyme concentration by 60%. The quantity and activity of the lysostaphin decreased during cheesemaking. Based on the amount of lysostaphin present in the starting cheesemilk, 10 to 15% of the lysostaphin was recovered in the whey, 21 to 55% in the cheese curd at d 1, and 21 to 36% in cheese stored at 4°C for 90 d. Enough of the lysostaphin secreted into milk by transgenic cows survived typical dairy processing conditions to impart potential value as a bioprotective agent against staphylococci in dairy foods.