Modelling the relation between bacterial growth and storage temperature in pasteurized milks of varying hygienic quality

The shelf-life of pasteurized milk was mainly determined by the level of contamination with Gram-negative psychrotrophic bacteria. The length of lag phase of the bacteria was also important, although the generation times of the naturally contaminating flora seemed to be of little relevance except for milks where the shelf-life exceeded 10 days at 6°C. The effect of temperature on growth of the contaminants could be accurately determined by the 'square root' plot but the conceptual minimum temperature for growth (T_o) varied. The variation was related to the quality of the pasteurized milk. Effects of temperature on generation time, length of lag phase and shelf-life were most marked at temperatures below 15°C.
The microflora of pasteurized milk varied significantly with storage temperature. At refrigeration temperatures, spoilage was mainly due to the growth of Pseudomonas spp. Enterobacteriaceae and Gram-positive bacteria assumed greater importance in the spoilage of milks stored at temperatures above 10°C. Milks of good quality also contained Bacillus spp and this group of bacteria were not detectable in milks with short shelf-lives.     

Aerobic spore-forming bacteria in bulk raw milk: factors influencing the numbers of psychrotrophic, mesophilic and thermophilic Bacillus spores

Psychrotrophic, mesophilic and thermophilic spore concentrations of Bacillus spp. were determined on a weekly basis in bulk raw milk samples obtained from a central processing facility, over one calendar year. These data were correlated with concentrations of metal ions, free amino acids and somatic cell counts obtained from the same samples, as well as local meteorological mean temperature and relative humidity measurements relating to the same test period. A heat treatment of 80°C for 20 min followed by the addition of L-alanine to the milk at 0.1% w/v and incubation at 55°C for 7 days gave optimal recovery conditions for thermophilic spores. Free amino acids, metal ions, somatic cell counts, temperature, and relative humidity measurements were each significantly correlated with the recovery of spores of Bacillus spp. from bulk raw milk, although no single factor was shown to demonstrate a consistent effect with the psychrotrophic, mesophilic and thermophilic spore groups studied.     

Factors influencing the recovery of psychrotrophic, mesophilic and thermophilic Bacillus spp from bulk raw milk

Because of the wide range of physiological properties found in the genus Bacillus one of the main problems in the standard procedure for isolating these organisms from milk and dairy products is the difficulty in defining conditions which are suitable for the activation and outgrowth of all spores present. This study investigated the effects of various raw milk heat treatments, the addition of L-alanine (a nutrient encouraging germination) to the milk after heat treatment, different incubation temperature-time combinations and two confirmatory media on the recovery of psychrotrophic, mesophilic and thermophilic Bacillus spp occurring in raw bulked milk. There was no significant difference (p >0.05) between the confirmatory media used, ie, starch milk agar and milk plate count agar. However, it was found that heat treatment, addition of L-alanine and the incubation period had significant effects on the recovery of the organisms from raw milk. The highest numbers of psychrotrophic and mesophilic spores were recovered after a heat treatment of 80C for 10 min followed by the addition of L-alanine to the milk at 0.1% wlv, and incubating at 6.5°C for 15 days for the former and 30C for 15 days for the latter. The highest numbers of thermophilic spores were recovered from raw milk by a heat treatment of 80C for 30 min, addition of L-alanine and incubating at 55°C for 7 days.     

The development of heat-resistant phosphatase activity in raw milk

The detection of phosphatase activity is used as a legal test to determine whether milk has been adequately pasteurized or whether it has been contaminated with raw milk. Occasional failures of the Milk Regulations phosphatase test were experienced by a processing dairy from stored silo milk. Trials demonstrated that the phosphatase was heat resistant and associated with a pasteurization-sensitive, psychrotrophic organism isolated from one supply. The standard total viable count at 30°C (TVC) of the supply was satisfactory at 4.59 log cfu/ml; however, the psychrotrophic count at 7°C was much higher at 5.61 log cfu/ml. The test milk after storage produced sufficient heat-resistant phosphatase activity to give a test failure when the psychrotrophic count reached about 7.09 log cfu/ml or greater. The occurrence of a failure was dependent on the initial numbers of psychrotophic bacteria, the amount of dilution with other milks and the storage time before processing. The psychrotrophic count of the test milk and the count of the phosphatase-producing isolate were found to increase by approximately one log cfu/ml each day on storage at 4°C. This investigation has shown that a phosphatase failure may indicate the development of microbial phosphatase rather than a process failure. A retest after laboratory pasteurization of any sample failing the test will assist in identifying any microbially produced heat-resistant phosphatase activity. While a TVC at 30°C will normally be expected to count most types of psychrotrophic organisms, this investigation has shown that on this occasion it did not detect specific psvchrotophic organisms which had contaminated the milk.     

Longitudinal assessment of dairy farm management practices associated with the presence of psychrotolerant Bacillales spores in bulk tank milk on 10 New York State dairy farms

The ability of certain spore-forming bacteria in the order Bacillales (e.g., Bacillus spp., Paenibacillus spp.) to survive pasteurization in spore form and grow at refrigeration temperatures results in product spoilage and limits the shelf life of high temperature, short time (HTST)-pasteurized fluid milk. To facilitate development of strategies to minimize contamination of raw milk with psychrotolerant Bacillales spores, we conducted a longitudinal study of 10 New York State dairy farms, which included yearlong monthly assessments of the frequency and levels of bulk tank raw milk psychrotolerant spore contamination, along with administration of questionnaires to identify farm management practices associated with psychrotolerant spore presence over time. Milk samples were first spore pasteurized (80°C for 12 min) and then analyzed for sporeformer counts on the initial day of spore pasteurization (SP), and after refrigerated storage (6°C) for 7, 14, and 21 d after SP. Overall, 41% of samples showed sporeformer counts of >20,000 cfu/mL at d 21, with Bacillus and Paenibacillus spp. being predominant causes of high sporeformer counts. Statistical analyses identified 3 management factors (more frequent cleaning of the bulk tank area, the use of a skid steer to scrape the housing area, and segregating problem cows during milking) that were all associated with lower probabilities of d-21 Bacillales spore detection in SP-treated bulk tank raw milk. Our data emphasize that appropriate on-farm measures to improve overall cleanliness and cow hygiene will reduce the probability of psychrotolerant Bacillales spore contamination of bulk tank raw milk, allowing for consistent production of raw milk with reduced psychrotolerant spore counts, which will facilitate production of HTST-pasteurized milk with extended refrigerated shelf life.     

The effect of extended low-temperature storage of raw milk on the quality of pasteurized and UHT milk

The effect of storage of raw milk at 2 and 6°C on the quality of pasteurized and UHT milks produced from them has been investigated. There was no difference in shelf-lives of pasteurized milks produced from raw milks which had no obvious physical defects, odours and taints after storage at 2 and 6°C. This was true for pasteurized milks in the presence and absence of post-heat-treatment contamination. However, pasteurized milks of good quality could be produced from more than 80% of raw milk samples which had been stored for up to 5 days at 2°C, but this was only possible with raw milks which had been stored at 6°C for 2 days.Failure rates of experimentally-produced UHT milks were much higher in products manufactured from raw milks stored at 6°C for 4 days than those produced from raw milks stored at 2°C for 4 days. The main cause of failure was due to thermostable bacterial protease associated with high levels of bacterial growth in the raw milks. Other causes of failure included spore-forming bacteria, which may have survived UHT processing, and other organisms probably introduced as contaminants on filling.     

Contamination flows of Bacillus cereus and spore-forming aerobic bacteria in a cooked,pasteurized and chilled zucchini purée processing line

A food processing plant producing pasteurized purées and its zucchini purée processing line were examined for contamination with aerobic and facultative anaerobic bacterial spores during a day's operation. Multiplication of spores was also monitored in the product stored under different conditions. High concentrations of Bacillus cereus spores were found in the soil in which the zucchinis were grown (4.6+/-0.3 log CFU/g), with a background spore population of 6.1+/-0.2 log CFU/g. In the processing plant, no B. cereus or psychrotrophic bacterial spores were detected on equipment. B. cereus and psychrotrophic bacterial spores were detected after enrichment in all samples of raw zucchinis, washed zucchinis, of two ingredients (starch and milk proteins) and in processed purée at each processing step. Steam cooking of raw zucchinis and pasteurization of purée in the final package significantly reduced spore numbers to 0.5+/-0.3 log CFU/g in the processed food. During storage, numbers of spore-forming bacteria increased up to 7.8+/-0.1 log CFU/g in purée after 5 days at 20-25 degrees C, 7.5+/-0.3 log CFU/g after 21 days at 10 degrees C and 3.8+/-1.1 log CFU/g after 21 days at 4 degrees C. B. cereus counts reached 6.4+/-0.5 log CFU/g at 20-25 degrees C, 4.6+/-1.9 log CFU/g at 10 degrees C, and remained below the detection threshold (1.7 log CFU/g) at 4 degrees C. Our findings indicate that raw vegetables and texturing agents such as milk proteins and starch, in spite of their low levels of contamination with bacterial spores and the heat treatments they undergo, may significantly contribute to the final contamination of cooked chilled foods. This contamination resulted in growth of B. cereus and psychrotrophic bacterial spores during storage of vegetable purée. Ways to eliminate such contamination in the processing line are discussed.     

Detection and fate of Bacillus anthracis (Sterne) vegetative cells and spores added to bulk tank milk

A preparation of Bacillus anthracis (Sterne strain) spores was used to evaluate commercially available reagents and portable equipment for detecting anthrax contamination by using real-time PCR and was used to assess the fate of spores added directly to bulk tank milk. The Ruggedized Advanced Pathogen Identification Device (RAPID) was employed to detect spores in raw milk down to a concentration of 2,500 spores per ml. Commercially available primers and probes developed to detect either the protective antigen gene or the lethal factor gene both provided easily read positive signals with the RAPID following extraction from milk with a commercially available DNA extraction kit. Nucleotide sequence analysis of the vrrA gene with the use of DNA extracted from spiked milk provided molecular data that readily identified the spores as B. anthracis with a 100% BLAST match to the Sterne and Ames strains and easily distinguished them from B. cereus. Physical-fate and thermal-stability studies demonstrated that spores and vegetative cells have a strong affinity for the cream fraction of whole milk. A single treatment at standard pasteurization temperatures, while 100% lethal to vegetative cells, had no effect on spore viability even 14 days after the treatment. Twenty-four hours after the first treatment, a second treatment at 72 degrees C for 15 s reduced the viability of the population by ca. 99% but still did not kill all of the spores. From these studies, we conclude that standard pasteurization techniques for milk would have little effect on the viability of B. anthracis spores and that raw or pasteurized milk poses no obstacles to the rapid detection of the spores by molecular techniques.     

Predictive modeling of Bacillus cereus spores in farm tank milk during grazing and housing periods

The shelf life of pasteurized dairy products depends partly on the concentration of Bacillus cereus spores in raw milk. Based on a translation of contamination pathways into chains of unit-operations, 2 simulation models were developed to quantitatively identify factors that have the greatest effect on the spore concentration in milk. In addition, the models can be used to determine the reduction in concentration that could be achieved via measures at the farm level. One model predicts the concentration when soil is the source of spores, most relevant during grazing of cows. The other model predicts the concentration when feed is the main source of spores, most relevant during housing of cows. It was estimated that when teats are contaminated with soil, 33% of the farm tank milk (FTM) contains more than 3 log₁₀ spores/L of milk. When feed is the main source, this is only 2%. Based on the predicted spore concentrations in FTM, we calculated that the average spore concentration in raw milk stored at the dairy processor during the grazing period is 3.5 log₁₀ spores/L of milk and during the housing period is 2.1 log₁₀ spores/L. It was estimated that during the grazing period a 99% reduction could be achieved if all farms minimize the soil contamination of teats and teat cleaning is optimized. During housing, reduction of the concentration by 60% should be feasible by ensuring spore concentrations in feed below 3 log₁₀ spores/g and a pH of the ration offered to the cows below 5. Implementation of these measures at the farm level ensures that the concentration of B. cereus spores in raw milk never exceeds 3 log₁₀ spores/L.     

Short communication: Effect of bactofugation of raw milk on counts and microbial diversity of psychrotrophs

Bactofugation is a centrifugal process for removing spores of microorganisms from milk, especially when it is destined for cheese making. Other microorganisms may be removed in bactofugation. This study aimed to verify the effect of milk bactofugation on the counts and microbial diversity of psychrotrophs. The raw milk was preheated (≈55°C) before being bactofuged, and samples were collected from 3 batches of milk: refrigerated raw, preheated, and bactofuged, representing the immediate conditions before and after bactofugation. The mean psychrotrophic counts of the 3 batches were 3.08 (±1.69) × 10⁶, 193 (±232), and 20 (±26) cfu/mL, respectively. Preheating was sufficient to eliminate 99.99% of the raw milk psychrotrophs, but bactofugation further reduced 89.66% of psychrotrophs from preheated milk. Lysinibacillus fusiformis was the most frequently isolated species (45.7%) among the psychrotrophs of raw milk and, proportionally, were more frequent in preheated (37.5%) and bactofuged (60%) milk. Bacillus invictae (20%), Enterococcus faecalis (10%), and Kurthia gibsonii (10%) were also isolated from bactofuged milk. Albeit in small numbers, psychrotrophic, thermoduric, and spore-forming bacteria with known proteolytic and lipolytic activity remained in the milk after bactofugation, which apparently had no effect on a specific population of microorganisms but proportionally reduced the entire psychrotrophic microbiota of raw milk.     

Isolation of Yersinia enterocolitica and Related Species from Red Meat and Milk

A total of 150 samples, 50 each of beef, lamb and pork from 10 local retail stores in the Brisbane metropolitan area and 50 pasteurized and 150 raw bovine bulk milk tank samples obtained from Queensland United Foods (QUF), were examined for the presence of Yersinia spp. over 1 yr. Two isolation protocols were used to recover the organism with subsequent biochemical and serological identification. A total of 114 isolates, consisting of Y. enterocolitica (23,12,15,40), Y. intermedia (0,3,5,1), Y. frederiksenii (4,1,0,10) were obtained from beef, lamb, pork, and milk, respectively. No pasteurized milk samples were positive for the organism. None of the isolated strains was found to harbor the virulence plasmid as indicated by the crystal violet-binding assay.     

A study on the prevalence of gram-negative bacteria in bulk tank milk

Bulk tank milk from 131 dairy herds in eastern South Dakota and western Minnesota were examined for coliforms and noncoliform bacteria. Coliforms were detected in 62.3% of bulk tank milk samples. Counts ranged from 0 to 4.7 log10 cfu/ml. The mean count was 3.4 log10 cfu/ml. Gram-negative noncoliform bacteria were observed in 76.3% of bulk tank milk. Counts ranged from 0 to 6.2 log10 cfu/ml. The mean count was 4.8 log10 cfu/ml. A total of 234 isolates from bulk tank milk were examined to species level; 205 isolates belonged to 28 species. Coliforms and gram-negative noncoliform bacteria accounted for 32.9 and 67.1% of the total isolates, respectively. Organisms such as Agrobacterium radiobacter, Bordetella spp., Comamonas testosteroni, Listonella damsela, Ochrobactrum anthropi, and Oligella urethralis were isolated from bulk tank milk in this study. These organisms have not been reported previously in bulk tank milk. A total of 116 isolates of Pseudomonas spp. were isolated from raw milk; 98 isolates belonged to nine Pseudomonas spp., and the remaining 18 isolates could not be identified to their species level. Pseudomonas was the most predominant genus. Pseudomonas fluorescens was the most predominant species isolated from bulk tank milk and accounted for 29.9% of all isolates examined. The results of the study suggest that counts of coliforms and noncoliform bacteria in bulk tank milk vary considerably. The isolates represent a wide variety of Gram-negative bacterial species. Examination of bulk tank milk for coliforms and noncoliform bacteria could provide an indication of current and potential problems associated with bacterial counts and milk quality.     

Selection of Tests for Monitoring the Bacteriological Quality of Refrigerated Raw Milk Supplies

Raw milk samples were collected from 10 producer bulk tanks. Samples were then subdivided so that milks were subsequently stored at 1.7, 4.4, 7.2, and 10.0°C for 24 and 48 h. After storage, samples were analyzed by seven plating methods: standard plate count, psychrotrophic bacterial count, rapid psychrotrophic count, preliminary incubation count, mesophilic plate count, laboratory pasteurized count, and coliform count by violet red bile agar technique. Impedance protocols on a Bactometer^® Model 123 for total count, psychrotrophic count, mesophilic count, and coliform count were also used to evaluate the bacteriological quality of the milks. Bacterial counts and impedance detection times were analyzed using nonparametric statistics. Impedance protocols for total count and psychrotrophic count were the best indicators of bacteriological quality. Preliminary incubation count was the best of the plating methods. The laboratory pasteurized count performed poorly. Impedance measurements provided information in the shortest time.     

Origins and levels of post pasteurization contamination of milk in the dairy and their effects on keeping quality

Bacterial post pasteurization contamination with psychrotrophic Gram-negative rods (GNR) was measured in commercial milks before and after transfer to retail containers. The tanks of pasteurized milk feeding the filling units contaminated milk less often (39% of samples) but usually at a higher level than the filling units (92% of samples). The number of GNR present had a considerable influence on the shelf life of milk, and the range found in commercially pasteurized milk was reflected in a wide range of shelf lives.     

Use of plasmid profiles and restriction endonuclease digest in environmental studies of Listeria spp. from raw milk

Forty-eight isolates of Listeria spp. (19 L. monocytogenes, 27 L. innocua, 2 L. welshimeri) from bulk raw milk were screened for plasmid DNA. These isolates were collected over a period of 1 year. Only L. innocua harboured plasmids (8/27 strains) which ranged in size 10-44 megadaltons. The plasmid bearing strains could be arranged into three groups 10 Md, 44 Md and 44 + 10 Md. In two farms where Listeria innocua were persistent in bulk raw milk different plasmids profiles were found (farm 1 and 3). In species carrying similar plasmid profiles (44 Md) isolated from the same bulk tank raw milk samples over a period of 2-4 months (farm 2) no similarities in restriction endonuclease digest patterns of the plasmids were observed. This study suggests there may be a constant influx of Listeria spp. into raw milk supplies on the farm.     

Occurrence of Yersinia enterocolitica in milk and dairy products in Morocco.

A total of 227 samples of milk and dairy products were examined for the presence of Yersinia enterocolitica. Yersinia spp. were recovered from 11 of 30 raw milks (36.6%), one of 20 pasteurized milks (5%), 15 of 63 traditional fermented milks (23.8%), seven of 94 cheeses and one of 20 cream samples (5%). The overall incidence of Y. enterocolitica in milk and dairy products was 6.6%. The other Yersinia species were Y. intermedia, Y. kristensenii, Y. frederiksenii and Y. pseudotuberculosis. Y. enterocolitica was detected only in raw milk (30% of the samples), in traditional fermented milks (6.3%) and in raw milk-made cheese (4%). The majority of the Y. enterocolitica isolates were of biotype 1 (environmental strains). The Celfulodin-Irgasan-Novobiocin (CIN) Agar was found to be more efficient than the Mac Conkey Agar in the isolation of Yersinia organisms.     

Impact of CO2 addition to milk on selected analytical testing methods

The addition of CO2 to raw milk and dairy products controls the growth of psychrotrophic bacteria at refrigeration temperatures. The objective of this study was to determine the effects of dissolved CO2 in milk on the performance of four important routine testing methods: antibiotic residue test, freezing point test, infrared milk component analysis, and alkaline phosphatase test. Raw or pasteurized whole milk was carbonated at <4 degrees C to contain approximately 0 (control), 200, 400, 600, and 1000 ppm of CO2. The addition of CO2 to raw milk up to 1000 ppm had no effect on the performance of the three antibiotic (beta-lactams) residue tests: IDEXX SNAP, Charm II Sequential Tablet, and Delvo-P Ampule. Milk freezing point decreased linearly with increasing concentration of dissolved CO2, from -0.543 degrees H (control) to -0.595 degrees H (1000 ppm). Carbonation to 1000 ppm decreased milk pH (measured at 38 degrees C) from 6.61 (control) to 6.15 (1000 ppm). The effects of CO2 on milk freezing point and pH were reversible upon removal of dissolved CO2. Increased CO2 levels in milk changed the infrared absorption spectrum of milk and caused the corrected lactose readings to decrease and the corrected fat B readings to increase. For the alkaline phosphatase tests, 0 (none), 0.05, 0.1, and 0.2% raw milk were deliberately added to pasteurized milks of six levels of carbonation (0 to 1000 ppm). The addition of CO2 did not influence the ability of Fluorophos, Charm PasLite, and Scharer Modified Rapid tests to differentiate between a pasteurized milk and a pasteurized milk with raw milk contamination.     

Prevalence,antimicrobial resistance,and molecular characterization of Campylobacter spp. in bulk tank milk and milk filters from US dairies

Campylobacter spp. are frequently isolated from dairy cows as commensal organisms. Sporadic Campylobacter infections in humans in the United States are generally attributed to poultry, but outbreaks are also commonly associated with dairy products, particularly unpasteurized or raw milk. Bulk tank milk samples and milk filters from US dairy operations were collected during the National Animal Health Monitoring System Dairy 2014 study and analyzed using real-time PCR and traditional culture techniques for the presence of thermophilic Campylobacter species. The weighted prevalence of operations from which we detected Campylobacter spp. in either bulk tank milk or milk filters was 24.9%. We detected Campylobacter spp. in a higher percentage of operations with 100–499 cows (42.8%) and 500 or more cows (47.5%) than in operations with 30–99 cows (6.5%). Campylobacter spp. were also more frequently detected in operations in the west than the east (45.9 and 22.6%, respectively). We isolated Campylobacter spp. from approximately half of PCR-positive samples, representing 12.5% (weighted prevalence) of operations. The majority (91.8%) of isolates were C. jejuni, but C. lari and C. coli were also isolated. We detected resistance to tetracycline in 68.4% of C. jejuni isolates, and resistance to ciprofloxacin and nalidixic acid in 13.2% of C. jejuni isolates. Based on pulsed-field gel electrophoresis, we found that dairy-associated C. jejuni were genotypically diverse, although clonal strains were isolated from different geographic regions. These results suggest that bulk tank milk can be contaminated with pathogenic Campylobacter spp., and that the consumption of unpasteurized or raw milk presents a potential human health risk.     

A survey of the microflora of raw and pasteurized milk and the sources of contamination in a milk processing plant in Addis Ababa, Ethiopia

The microorganisms present in raw and pasteurized milk and the sources of contamination in the milk after it had arrived at the processing plant in Addis Ababa were studied. The lowest count registered for raw milk samples was 4 X 10(7) cfu/ml while the highest was 1 X 10(9) cfu/ml. Pasteurized milk had mesophilic aerobic counts of 7 X 10(5) cfu/ml as it left the pasteurizing unit, but the population increased 2- to 4-fold as a result of subsequent contamination. Of the total counts in raw milk, psychrophilic, thermoduric and thermophilic organisms made up 98.1, 1.4 and 0.5% respectively. In pasteurized milk, the amounts were 53.0, 39.5 and 7.5% respectively. Samples of milk pasteurized in the laboratory contained only 74.5% thermoduric and 25.5% thermophilic organisms. The isolates mostly belonged to the genera Bacillus, Streptococcus, Lactobacillus, Arthrobacter, Alcaligenes, Aeromonas and Pseudomonas. Cocci were more predominant than rod-shaped bacteria. Of the rod-shaped bacteria, 73% were Gram-negative. The utensils holding the raw and pasteurized milk and the plastic sheets used for bagging the pasteurized milk contributed unusually high numbers of bacteria which were either thermoduric or thermophilic. More isolates were obtained from the pasteurized than the raw milk. The keeping quality of the pasteurized milk was found to be much lower than that of the laboratory-pasteurized milk.     

Isolation and genetic identification of spore-forming bacteria associated with concentrated-milk processing in Nebraska

Spore-forming bacteria are heat-resistant microorganisms capable of surviving and germinating in milk after pasteurization. They have been reported to affect the quality of dairy products by the production of enzymes (lipolytic and proteolytic) under low-temperature conditions in fluid milk, and have become a limiting factor for milk powder in reaching some selective markets. The objective of this research was to isolate and identify the population of spore-forming bacteria (psychrotrophic and thermophilic strains) associated with concentrated milk processing in Nebraska. During 2 seasons, in-process milk samples from a commercial plant (raw, pasteurized, and concentrated) were collected and heat-treated (80°C/12 min) to recover only spore-formers. Samples were spread-plated using standard methods agar and incubated at 32°C to enumerate mesophilic spore counts. Heat-treated samples were also stored at 7°C and 55°C to recover spore-formers that had the ability to grow under those temperature conditions. Isolates obtained from incubation or storage conditions were identified using molecular techniques (16S or rpoB sequencing). Based on the identification of the isolates and their relatedness, strains found in raw, pasteurized, and concentrated milk were determined to be similar. Paenibacillus spp. were associated with both raw and concentrated milk. Due to their known ability to cause spoilage under refrigeration, this shows the potential risk associated with the transferring of these problematic organisms into other dairy products. Other Bacillus species found in concentrated milk included Bacillus clausii, Bacillus subtilis, Lysinibacillus sp., Bacillus safensis, Bacillus licheniformis, Bacillus sonorensis, and Brevibacillus sp., with the last 3 organisms being capable of growing at thermophilic temperatures. These strains can also be translocated to other dairy products, such as milk powder, representing a quality problem. The results of this research highlight the importance of understanding spore-formers associated with the processing of condensed milk, which then may allow for specific interventions to be applied to control these microorganisms in this processing chain. To our knowledge, this is the first study evaluating spore-formers associated with concentrated milk in the United States.