1
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Lan X, Wu S, Du Q, Min L. The Investigation of Changes in Bacterial Community of Pasteurized Milk during Cold Storage. Foods 2024; 13:451. [PMID: 38338585 PMCID: PMC10855270 DOI: 10.3390/foods13030451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 12/25/2023] [Accepted: 12/30/2023] [Indexed: 02/12/2024] Open
Abstract
The quality of pasteurized milk is commonly assessed through microbiological analysis, with variations in storage conditions significantly impacting the suppression of bacterial growth throughout the milk's shelf life. This study investigated the dynamics of total bacterial counts (TBCs) and bacterial community shifts in milk that underwent pasteurization at 80 °C for 15 s. The milk was subsequently stored at 4 °C for varying intervals of 1, 4, 7, 10, 13, and 16 days. Culture-based testing revealed a significant TBC increase during the storage period spanning 1 to 16 days (up to -log10 4.2 CFU/mL at day 16). The TBC in pasteurized milk exhibited accelerated microbial growth from day 13 onwards, ultimately peaking on day 16. Bacillus was detected through 16S rRNA identification. Principal component analysis demonstrated a significant impact of storage time on bacterial communities in pasteurized milk. Analysis of bacterial diversity revealed a negative correlation between the Shannon index and the duration of pasteurized milk storage. Using high-throughput sequencing, Streptococcus and Acinetobacter were detected as prevalent bacterial genera, with Streptococcus dysgalactiae and Streptococcus uberis showing as dominant taxa. The presence of Streptococcus dysgalactiae and Streptococcus uberis in pasteurized milk might be attributed to the initial contamination from raw milk with mastitis. This study offers new evidence of the prevalence of bacterial community in pasteurized milk, thereby adding value to the enhancement of quality control and the development of strategies for reducing microbial risks.
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Affiliation(s)
- Xinyi Lan
- College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China;
| | - Shuyan Wu
- Hopkirk Research Institute, AgResearch Ltd., Palmerston North 4442, New Zealand;
| | - Qijing Du
- Grasslands Research Centre, AgResearch Ltd., Palmerston North 4472, New Zealand;
- College of Food Science and Engineering, Qingdao Agricultural University, Qingdao 266109, China
| | - Li Min
- Ministry of Agriculture Key Laboratory of Animal Nutrition and Feed Science in South China, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
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2
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Evanowski RL, Murphy SI, Wiedmann M, Martin NH. Low-cost, on-farm intervention to reduce spores in bulk tank raw milk benefits producers, processors, and consumers. J Dairy Sci 2023; 106:1687-1694. [PMID: 36710187 DOI: 10.3168/jds.2022-22372] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 10/12/2022] [Indexed: 01/29/2023]
Abstract
Bacterial spores, which are found in raw milk, can survive harsh processing conditions encountered in dairy manufacturing, including pasteurization and drying. Low-spore raw milk is desirable for dairy industry stakeholders, especially those who want to extend the shelf life of their product, expand their distribution channels, or reduce product spoilage. A recent previous study showed that an on-farm intervention that included washing towels with chlorine bleach and drying them completely, as well as training milking parlor employees to focus on teat end cleaning, significantly reduced spore levels in bulk tank raw milk. As a follow up to that previous study, here we calculate the costs associated with that previously described intervention as ranging from $9.49 to $13.35 per cow per year, depending on farm size. A Monte Carlo model was used to predict the shelf life of high temperature, short time fluid milk processed from raw milk before and after this low-cost intervention was applied, based on experimental data collected in a previous study. The model predicted that 18.24% of half-gallon containers of fluid milk processed from raw milk receiving no spore intervention would exceed the pasteurized milk ordinance limit of 20,000 cfu/mL by 17 d after pasteurization, while only 16.99% of containers processed from raw milk receiving the spore intervention would reach this level 17 d after pasteurization (a reduction of 1.25 percentage points and a 6.85% reduction). Finally, a survey of consumer milk use was conducted to determine how many consumers regularly consume fluid milk near or past the date printed on the package (i.e., code date), which revealed that over 50% of fluid milk consumers surveyed continue to consume fluid milk after this date, indicating that a considerable proportion of consumers are exposed to fluid milk that is likely to have high levels spore-forming bacterial growth and possibly associated quality defects (e.g., flavor or odor defects). This further highlights the importance of reducing spore levels in raw milk to extend pasteurized fluid milk shelf life and thereby reducing the risk of adverse consumer experiences. Processors who are interested in extending fluid milk shelf life by controlling the levels of spores in the raw milk supply should consider incentivizing low-spore raw milk through premium payments to producers.
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Affiliation(s)
- Rachel L Evanowski
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Sarah I Murphy
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Martin Wiedmann
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Nicole H Martin
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853.
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3
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Lott T, Wiedmann M, Martin N. Shelf-life storage temperature has a considerably larger effect than high-temperature, short-time pasteurization temperature on the growth of spore-forming bacteria in fluid milk. J Dairy Sci 2023; 106:3838-3855. [DOI: 10.3168/jds.2022-22832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 12/05/2022] [Indexed: 03/31/2023]
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4
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Hwang JH, Jung AH, Yu SS, Park SH. Rapid freshness evaluation of cow milk at different storage temperatures using in situ electrical conductivity measurement. INNOV FOOD SCI EMERG 2022. [DOI: 10.1016/j.ifset.2022.103113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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5
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Nabilah UU, Sitanggang AB, Dewanti‐Hariyadi R, Sugiarto AT, Purnomo EH. Meta‐analysis: Microbial inactivation in milk using Pulsed Electric Field (
PEF
). Int J Food Sci Technol 2022. [DOI: 10.1111/ijfs.15942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Uray Ulfah Nabilah
- Department of Food Science and Technology, Faculty of Agricultural Engineering and Technology IPB University Bogor 16680 Indonesia
| | - Azis Boing Sitanggang
- Department of Food Science and Technology, Faculty of Agricultural Engineering and Technology IPB University Bogor 16680 Indonesia
| | - Ratih Dewanti‐Hariyadi
- Department of Food Science and Technology, Faculty of Agricultural Engineering and Technology IPB University Bogor 16680 Indonesia
- Southeast Asian Food and Agricultural Science and Technology Center IPB University Bogor 16680 Indonesia
| | - Anto Tri Sugiarto
- Technical Implementation Unit for Instrumentation Development, BRIN Bandung 40135 Indonesia
| | - Eko Hari Purnomo
- Department of Food Science and Technology, Faculty of Agricultural Engineering and Technology IPB University Bogor 16680 Indonesia
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6
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Can ultrasound treatment replace conventional high temperature short time pasteurization of milk? A critical review. Int Dairy J 2022. [DOI: 10.1016/j.idairyj.2022.105375] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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7
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Kononoff PJ. Gold open access-A new era for the Journal of Dairy Science. J Dairy Sci 2021; 105:1-2. [PMID: 34949435 DOI: 10.3168/jds.2021-21555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 11/09/2021] [Indexed: 11/19/2022]
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8
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Bhanduriya K, Mealy L, Anand S, Metzger L. Effect of midday pasteurizer washing on thermoduric organisms and their progression through Cheddar cheese manufacturing and ripening. J Dairy Sci 2021; 105:109-122. [PMID: 34656352 DOI: 10.3168/jds.2021-20446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 08/31/2021] [Indexed: 11/19/2022]
Abstract
Thermoduric bacteria are known to affect the quality of Cheddar cheese, with manifested defects including slits, weak body, and blowing. Thermoduric bacteria are likely to increase in numbers during cheese-making, as in-process conditions are conducive to proliferation. The present study was conducted to track thermoduric bacterial progression during an 18- to 20-h Cheddar cheese production run and during ripening when the pasteurizer was washed at midway through the production day. This study also correlated a broad range of chemical changes to the growth of thermoduric bacteria during ripening. Three independent cheese trials were performed at 3.5- ± 0.5-mo intervals. Samples were drawn in duplicates at 4 different times of the day: at the start of the run (vat 1), prior to a midday wash of the pasteurizer (vat 20), after the midday wash of the pasteurizer (vat 21), and at the end of the run (vat 42) for raw milk, pasteurized milk, and cheese. Cheeses were also tested during ripening for 6 mo. Results showed that raw milk total bacterial counts comprised 0.24% thermoduric mesophiles (TM) and 0.12% thermoduric thermophiles (TT). The thermoduric thermophilic bacterial counts increased by log10 1.23 during the pasteurizer run of 9 to 10 h, indicating a buildup of thermoduric thermophilic bacteria during the pasteurization process itself. Midday washing reduced thermophilic counts by log10 1.36, as evident by pre- and post-midday wash counts. However, a thermophilic buildup during post-midday wash was again noticed near the end of the 20-h run. We found that TT bacteria decreased in the first 60 d of ripening, whereas TM bacteria increased during the same period. However, TT bacteria increased later during 60 to 180 d of ripening. Bacillus licheniformis was the most frequently isolated bacteria in this study and was recovered at all production stages sampled during the cheese-making and ripening. We observed a significant increase in the level of orotic and uric acids in the vat made at the end of the day. No significant difference in the overall chemical composition, proteolysis, sugar, or other organic acids was observed in cheese made at the start versus the end of the production run.
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Affiliation(s)
- Khilendra Bhanduriya
- Midwest Dairy Foods Research Center, Dairy and Food Science Department, South Dakota State University, Brookings 57007
| | - Laura Mealy
- Midwest Dairy Foods Research Center, Dairy and Food Science Department, South Dakota State University, Brookings 57007
| | - Sanjeev Anand
- Midwest Dairy Foods Research Center, Dairy and Food Science Department, South Dakota State University, Brookings 57007.
| | - Lloyd Metzger
- Midwest Dairy Foods Research Center, Dairy and Food Science Department, South Dakota State University, Brookings 57007
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9
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Martin NH, Torres-Frenzel P, Wiedmann M. Invited review: Controlling dairy product spoilage to reduce food loss and waste. J Dairy Sci 2020; 104:1251-1261. [PMID: 33309352 DOI: 10.3168/jds.2020-19130] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 09/16/2020] [Indexed: 01/30/2023]
Abstract
Food loss and waste is a major concern in the United States and globally, with dairy foods representing one of the top categories of food lost and wasted. Estimates indicate that in the United States, approximately a quarter of dairy products are lost at the production level or wasted at the retail or consumer level annually. Premature microbial spoilage of dairy products, including fluid milk, cheese, and cultured products, is a primary contributor to dairy food waste. Microbial contamination may occur at various points throughout the production and processing continuum and includes organisms such as gram-negative bacteria (e.g., Pseudomonas), gram-positive bacteria (e.g., Paenibacillus), and a wide range of fungal organisms. These organisms grow at refrigerated storage temperatures, often rapidly, and create various degradative enzymes that result in off-odors, flavors, and body defects (e.g., coagulation), rendering them inedible. Reducing premature dairy food spoilage will in turn reduce waste throughout the dairy continuum. Strategies to reduce premature spoilage include reducing raw material contamination on-farm, physically removing microbial contaminants, employing biocontrol agents to reduce outgrowth of microbial contaminants, tracking and eliminating microbial contaminants using advanced molecular microbiological techniques, and others. This review will address the primary microbial causes of premature dairy product spoilage and methods of controlling this spoilage to reduce loss and waste in dairy products.
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Affiliation(s)
- N H Martin
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853.
| | - P Torres-Frenzel
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - M Wiedmann
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
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10
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Wang D, Fritsch J, Moraru CI. Shelf life and quality of skim milk processed by cold microfiltration with a 1.4-μm pore size membrane, with or without heat treatment. J Dairy Sci 2019; 102:8798-8806. [DOI: 10.3168/jds.2018-16050] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 04/24/2019] [Indexed: 11/19/2022]
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11
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Ziyaina M, Govindan BN, Rasco B, Coffey T, Sablani SS. Monitoring Shelf Life of Pasteurized Whole Milk Under Refrigerated Storage Conditions: Predictive Models for Quality Loss. J Food Sci 2018; 83:409-418. [PMID: 29369352 DOI: 10.1111/1750-3841.13981] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/25/2017] [Accepted: 10/11/2017] [Indexed: 11/26/2022]
Abstract
The shelf life of pasteurized milk is generally determined through microbiological analysis. The objective of this study was to correlate microbial quality parameters then to design predictive models for shelf life of pasteurized milk. We analyzed pasteurized milk (3.9% fat) for aerobic plate counts (APCs), psychrotrophic bacteria counts (PBCs), and Bacillus spp. counts at 5, 7, 10, 13, 15, and 19 (±1 °C) to the end of storage time. We also monitored titratable acidity, pH, and, lipase, and protease activity and correlated this with APC, which is the principal index defining shelf life. Results indicate that the shelf life of pasteurized milk was 24, 36, and 72 h at 19, 15, and 13 °C respectively, as determined by APC and acidity indicators. However, milk stored at lower temperatures of 5, 7, and 10 °C had longer shelf life of 30, 24, and 12 d, respectively. A sharp increase in titratable acidity, while decrease pH were observed when APCs reached 5.0 log10 CFU/mL at all storage temperatures. Lipase and protease activities increased with storage temperature. At 5 and 7 °C, however, protease activity was very low. Therefore, we eliminated this parameter from our quality parameters as a potential spoilage indicator. PRACTICAL APPLICATION Findings of this research are useful for monitoring the quality of commercial pasteurized milk, particularly in locations where environmental conditions make longer storage difficult. The study also provides valuable information for development of colorimetric shelf life indicators.
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Affiliation(s)
- Mohamed Ziyaina
- School of Food Science, Washington State Univ., Pullman, WA 99164-6376, U.S.A
| | - Byju N Govindan
- Dept. of Entomology, The College of Food, Agricultural and Natural Resource Sciences, Univ. of Minnesota, MN, 55108-1037, U.S.A
| | - Barbara Rasco
- School of Food Science, Washington State Univ., Pullman, WA 99164-6376, U.S.A
| | - Todd Coffey
- Dept. of Mathematics and Statistics, Washington State Univ., Pullman, WA 99164- 3113, U.S.A
| | - Shyam S Sablani
- Dept. of Biological Systems Engineering, Washington State Univ., Pullman, WA 99164-6120, U.S.A
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12
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Lee A, Barbano D, Drake M. Short communication: The effect of raw milk cooling on sensory perception and shelf life of high-temperature, short-time (HTST)–pasteurized skim milk. J Dairy Sci 2016; 99:9659-9667. [DOI: 10.3168/jds.2016-11771] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Accepted: 09/03/2016] [Indexed: 11/19/2022]
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13
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Murphy SC, Martin NH, Barbano DM, Wiedmann M. Influence of raw milk quality on processed dairy products: How do raw milk quality test results relate to product quality and yield? J Dairy Sci 2016; 99:10128-10149. [DOI: 10.3168/jds.2016-11172] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 08/03/2016] [Indexed: 11/19/2022]
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14
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VanderKelen JJ, Mitchell RD, Laubscher A, Black MW, Goodman AL, Montana AK, Dekhtyar AM, Jimenez-Flores R, Kitts CL. Short communication: Typing and tracking Bacillaceae in raw milk and milk powder using pyroprinting. J Dairy Sci 2015; 99:146-51. [PMID: 26585475 DOI: 10.3168/jds.2015-9656] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 09/23/2015] [Indexed: 11/19/2022]
Abstract
Contamination of fluid and processed milk products with endospore-forming bacteria, such as Bacillaceae, affect milk quality and longevity. Contaminants come from a variety of sources, including the dairy farm environment, transportation equipment, or milk processing machinery. Tracking the origin of bacterial contamination to allow specifically targeted remediation efforts depends on a reliable strain-typing method that is reproducible, fast, easy to use, and amenable to computerized analysis. Our objective was to adapt a recently developed genotype-based Escherichia coli strain-typing method, called pyroprinting, for use in a microbial source-tracking study to follow endospore-forming bacillus bacteria from raw milk to powdered milk. A collection of endospores was isolated from both raw milk and its finished powder, and, after germination, the vegetative cells were subject to the pyroprinting protocol. Briefly, a ribosomal DNA intergenic transcribed spacer present in multiple copies in Bacillaceae genomes was amplified by the PCR. This multicopy locus generated a mixed PCR product that was subsequently subject to pyrosequencing, a quantitative real-time sequencing method. Through a series of enzymatic reactions, each nucleotide incorporation event produces a photon of light that is quantified at each nucleotide dispensation. The pattern of light peaks generated from this mixed template reaction is called a pyroprint. Isolates with pyroprints that match with a Pearson correlation of 0.99 or greater are considered to be in the same group. The pyroprint also contains some sequence data useful for presumptive species-level identification. This method identified groups with isolates from raw milk only, from powdered milk only, or from both sources. This study confirms pyroprinting as a rapid, reproducible, automatically digitized tool that can be used to distinguish bacterial strains into taxonomically relevant groups and, thus, indicate probable origins of bacterial contamination in powdered milk.
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Affiliation(s)
- Jennifer J VanderKelen
- Center for Applications in Biotechnology, California Polytechnic State University, San Luis Obispo 93407
| | | | - Andrea Laubscher
- Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo 93407
| | - Michael W Black
- Center for Applications in Biotechnology, California Polytechnic State University, San Luis Obispo 93407; Department of Biological Sciences, California Polytechnic State University, San Luis Obispo 93407
| | - Anya L Goodman
- Center for Applications in Biotechnology, California Polytechnic State University, San Luis Obispo 93407; Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo 93407
| | | | - Alexander M Dekhtyar
- Center for Applications in Biotechnology, California Polytechnic State University, San Luis Obispo 93407; Department of Computer Science, California Polytechnic State University, San Luis Obispo 93407
| | - Rafael Jimenez-Flores
- Center for Applications in Biotechnology, California Polytechnic State University, San Luis Obispo 93407; Department of Dairy Science, California Polytechnic State University, San Luis Obispo 93407
| | - Christopher L Kitts
- Center for Applications in Biotechnology, California Polytechnic State University, San Luis Obispo 93407; Department of Biological Sciences, California Polytechnic State University, San Luis Obispo 93407.
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15
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Andrus AD, Campbell B, Boor KJ, Wiedmann M, Martin NH. Short communication: Postpasteurization hold temperatures of 4 or 6°C, but not raw milk holding of 24 or 72 hours, affect bacterial outgrowth in pasteurized fluid milk. J Dairy Sci 2015; 98:7640-3. [PMID: 26342986 DOI: 10.3168/jds.2015-9531] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 07/18/2015] [Indexed: 11/19/2022]
Abstract
As fluid milk processors continue to reduce microbial spoilage in fluid milk through improved control of postpasteurization contamination and psychrotolerant sporeformer outgrowth, it is necessary to identify strategies to further improve the quality and extend the shelf life of fluid milk products that are high-temperature, short-time pasteurized. Solutions that optimize product quality, and are economically feasible, are of particular interest to the dairy industry. To this end, this study examined the effects of raw milk holding time and temperature of pasteurized milk storage over shelf life on bacterial growth. In 3 independent replicates, raw milk was stored for 24 and 72 h before pasteurization at 76°C for 25s and then incubated at 3 different storage conditions: (1) 4°C for 21d; (2) 4°C for the first 48 h, then 6°C for the duration of the 21-d shelf life; or (3) 6°C for 21d. Total bacteria counts were assessed initially and on d 7, 14, and 21. No substantial difference in bacterial growth over shelf life was observed between samples processed from raw milk held for 24 versus 72 h. A significantly lower bacterial load was seen at d 21 after pasteurization in samples held at 4°C, versus 4°C for the first 48 h followed by 6°C for the duration of the 21-d shelf life and samples held at 6°C for 21d. This work demonstrates the importance of maintaining control of the fluid milk cold chain throughout postpasteurization, transportation, and retail storage on fluid milk microbial quality.
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Affiliation(s)
- Alexis D Andrus
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Brynne Campbell
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Kathryn J Boor
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Martin Wiedmann
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Nicole H Martin
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853.
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16
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17
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Miller R, Kent D, Boor K, Martin N, Wiedmann M. Different management practices are associated with mesophilic and thermophilic spore levels in bulk tank raw milk. J Dairy Sci 2015; 98:4338-51. [DOI: 10.3168/jds.2015-9406] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 03/30/2015] [Indexed: 11/19/2022]
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18
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Trmčić A, Martin NH, Boor KJ, Wiedmann M. A standard bacterial isolate set for research on contemporary dairy spoilage. J Dairy Sci 2015; 98:5806-17. [PMID: 26026752 DOI: 10.3168/jds.2015-9490] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 04/11/2015] [Indexed: 11/19/2022]
Abstract
Food spoilage is an ongoing issue that could be dealt with more efficiently if some standardization and unification was introduced in this field of research. For example, research and development efforts to understand and reduce food spoilage can greatly be enhanced through availability and use of standardized isolate sets. To address this critical issue, we have assembled a standard isolate set of dairy spoilers and other selected nonpathogenic organisms frequently associated with dairy products. This publicly available bacterial set consists of (1) 35 gram-positive isolates including 9 Bacillus and 15 Paenibacillus isolates and (2) 16 gram-negative isolates including 4 Pseudomonas and 8 coliform isolates. The set includes isolates obtained from samples of pasteurized milk (n=43), pasteurized chocolate milk (n=1), raw milk (n=1), cheese (n=2), as well as isolates obtained from samples obtained from dairy-powder production (n=4). Analysis of growth characteristics in skim milk broth identified 16 gram-positive and 13 gram-negative isolates as psychrotolerant. Additional phenotypic characterization of isolates included testing for activity of β-galactosidase and lipolytic and proteolytic enzymes. All groups of isolates included in the isolate set exhibited diversity in growth and enzyme activity. Source data for all isolates in this isolate set are publicly available in the FoodMicrobeTracker database (http://www.foodmicrobetracker.com), which allows for continuous updating of information and advancement of knowledge on dairy-spoilage representatives included in this isolate set. This isolate set along with publicly available isolate data provide a unique resource that will help advance knowledge of dairy-spoilage organisms as well as aid industry in development and validation of new control strategies.
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Affiliation(s)
- A Trmčić
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14850
| | - N H Martin
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14850
| | - K J Boor
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14850
| | - M Wiedmann
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14850.
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19
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Stasiewicz MJ, Martin N, Laue S, Gröhn YT, Boor KJ, Wiedmann M. Responding to bioterror concerns by increasing milk pasteurization temperature would increase estimated annual deaths from listeriosis. J Food Prot 2014; 77:696-712. [PMID: 24780323 DOI: 10.4315/0362-028x.jfp-13-191] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
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.
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Affiliation(s)
- Matthew J Stasiewicz
- Department of Food Science, College of Agriculture and Life Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
| | - Nicole Martin
- Department of Food Science, College of Agriculture and Life Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
| | - Shelley Laue
- Department of Food Science, College of Agriculture and Life Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
| | - Yrjo T Gröhn
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
| | - Kathryn J Boor
- Department of Food Science, College of Agriculture and Life Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
| | - Martin Wiedmann
- Department of Food Science, College of Agriculture and Life Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
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Martin N, Carey N, Murphy S, Wiedmann M, Boor K. A decade of improvement: New York State fluid milk quality. J Dairy Sci 2012; 95:7384-90. [DOI: 10.3168/jds.2012-5767] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 08/30/2012] [Indexed: 11/19/2022]
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