Category Archives: Dairy Research

Milk Quality Improvement Program publishes recommendations for enumerating bacterial spores in dairy powder

By Nicole Martin

Bacterial endospores, or spores, are an important microbial markers in many milk powders, especially in products that will be used in certain products like infant formula. There is no single standard method for enumerating spores in dairy powder that is used across the industry, which can lead to large differences in the spore test results. The basis of spore testing is similar for all methods, a sample of milk powder is rehydrated, heat treated to eliminate all bacterial cells with the exception of spores, plated on microbiological media and then incubated before enumeration. Differences in commonly used heat treatment times and temperatures, plating methods, microbiological media and incubation temperatures ultimately lead to hundreds of possible unique spore tests being used in the dairy industry. This lack of standardization for milk powder spore testing methods leads to considerable challenges for the dairy industry, including; (i) inability to benchmark against industry spore levels; (ii) lack of comparability between laboratories, and; (iii) potential competitive disadvantage against companies using methods that result in lower spore counts. To address these issues, our team evaluated 48 different spore tests on commercial milk powders with the goal of ultimately recommending a set of spore testing methods that would reliably enumerate spores in milk powders. Our analysis identified a set of three spore test methods that were able to reliably enumerate spores in commercial dairy powders. These methods include:

Mesophilic Spore Count: 80°C/12 min heat treatment followed by spread plating on Plate Count Milk Agar (PCMA) and incubated at 32°C for 48 h
Highly Heat Resistant Thermophilic Spore Count: 100°C/30 min heat treatment followed by spread plating on PCMA and incubated at 55°C for 48 h
Specially Thermoresistant Spore Enumeration: 100°C/30 min heat treatment followed by spread plating on PCMA and incubated at 55°C for 48 h

Our research described here was recently published in the Journal of Dairy Science (https://doi.org/10.3168/jds.2020-19313) and provides industry with a practical set of methods that addresses key challenges with milk powder spore testing. To learn more about spore testing in milk powders or to get a copy of this publication email Nicole Martin at nicole.martin@cornell.edu.

Recent Publications March 2021

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Belias, Alexandra, Laura K. Strawn, Martin Wiedmann, and Daniel Weller. “Small Produce Farm Environments Can Harbor Diverse Listeria Monocytogenes and Listeria Spp. Populations.” Journal of Food Protection 84, no. 1 (January 1, 2021): 113–21. https://doi.org/10.4315/JFP-20-179.

Cheng, Rachel A., and Martin Wiedmann. “Recent Advances in Our Understanding of the Diversity and Roles of Chaperone-Usher Fimbriae in Facilitating Salmonella Host and Tissue Tropism.” Frontiers in Cellular and Infection Microbiology 10 (2021). https://doi.org/10.3389/fcimb.2020.628043.

Liao, Jingqiu, Peter Bergholz, and Martin Wiedmann. “Adjacent Terrestrial Landscapes Impact the Biogeographical Pattern of Soil Escherichia Coli Strains in Produce Fields by Modifying the Importance of Environmental Selection and Dispersal.” Applied and Environmental Microbiology 87, no. 6 (February 26, 2021). https://doi.org/10.1128/AEM.02516-20.

Ma, Yvonne, Jessica Chen, Karen Fong, Stephanie Nadya, Kevin Allen, Chad Laing, Kim Ziebell, et al. “Antibiotic Resistance in Shiga Toxigenic Escherichia Coli Isolates from Surface Waters and Sediments in a Mixed Use Urban Agricultural Landscape.” Antibiotics 10, no. 3 (March 2021): 237. https://doi.org/10.3390/antibiotics10030237.

Makki, Ghadeer, and Samuel D. Alcaine. “Evaluation of Lactose Oxidase as Enzymatic Antifungal Control for Penicillium Spoilage in Yogurt.” Journal of Dairy Science, March 6, 2021. https://doi.org/10.3168/jds.2020-19602.

Makki, Ghadeer M., Sarah M. Kozak, Katharine G. Jencarelli, and Samuel D. Alcaine. “Evaluation of the Efficacy of Commercial Protective Cultures to Inhibit Mold and Yeast in Cottage Cheese.” Journal of Dairy Science, January 15, 2021. https://doi.org/10.3168/jds.2020-19136.

Reichler, S. J., S. I. Murphy, N. H. Martin, and M. Wiedmann. “Identification, Subtyping, and Tracking of Dairy Spoilage-Associated Pseudomonas by Sequencing the IleS Gene.” Journal of Dairy Science, January 15, 2021. https://doi.org/10.3168/jds.2020-19283.

Rivera Flores, Viviana K., Timothy A. DeMarsh, and Samuel D. Alcaine. “Lactose Oxidase: Enzymatic Control of Pseudomonas to Delay Age Gelation in UHT Milk.” Journal of Dairy Science, December 25, 2020. https://doi.org/10.3168/jds.2020-19452.

Ubeyitogullari, Ali, and Syed S. H. Rizvi. “Heat Stability of Emulsions Using Functionalized Milk Protein Concentrate Generated by Supercritical Fluid Extrusion.” Food & Function 11, no. 12 (December 17, 2020): 10506–18. https://doi.org/10.1039/D0FO02271C.

Wang, Linran, and Carmen I. Moraru. “High-Pressure Structuring of Milk Protein Concentrate: Effect of PH and Calcium.” Journal of Dairy Science 104, no. 4 (April 1, 2021): 4074–83. https://doi.org/10.3168/jds.2020-19483.

———. “Structure and Shelf Stability of Milk Protein Gels Created by Pressure-Assisted Enzymatic Gelation.” Journal of Dairy Science 104, no. 4 (April 2021): 3970–79. https://doi.org/10.3168/jds.2020-19484.

Zwietering, Marcel H, Alberto Garre, Martin Wiedmann, and Robert L Buchanan. “All Food Processes Have a Residual Risk, Some Are Small, Some Very Small and Some Are Extremely Small: Zero Risk Does Not Exist.” Current Opinion in Food Science 39 (June 1, 2021): 83–92. https://doi.org/10.1016/j.cofs.2020.12.017.

Services to Know About in 2021

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There are many services offered through our Extension Program, the Food Safety Laboratory, and the Expertise of our team that can help your organization, whether it’s to address an acute or persistent food safety or quality issues, to prepare for an audit, to implement or improve continuous improvement or troubleshooting procedures, or to develop improved training programs for a team or for individuals that you want to grow in your organization. We can help you take things off your to-do list in 2021.

The list below encompasses many of the services we encourage businesses to take advantage of. If your organization is interested in any of the services listed below, or more specific support not outlined below, please reach out to Anika Gianforte at adz8@cornell.edu at any point, or submit a request through our website. We also encourage individuals and organizations to reach out to us with any questions or issues through our “Ask an Expert” platform. These questions will be directed to the appropriate team member. These services in combination with our workshop programming allow us to equip food businesses with knowledge and tools to flourish.

Lab for Molecular Typing: The lab offers a wide variety of technologies to subtype, identify, and characterize microorganisms to the genus, species, subspecies, and subtype level including Pulsed Field Gel Electrophoresis (PFGE) and Whole Genome Sequencing (WGS). Services are strictly confidential. We do not submit isolates or patterns to the CDC unless specifically requested by the submitter/customer. A considerable number of companies use our services to enhance their environmental monitoring programs or to help troubleshoot microbiological issues.
Pathogen Environmental Monitoring Validation Services: We are available to review or assist in the development of your pathogen environmental monitoring programs. We also validate environmental monitoring programs through plant visits with collection of samples; this will help you determine whether your program is designed and implemented correctly to identify any issues you may have; we can also design these visits to represent mock FDA “swabathons”, helping you ensure your company is ready for a visit by the FDA or another regulatory agency.
Process Authority Review: For those who require a scheduled process to begin processing a dairy food product, our team member Rob Ralyea will review your proposed process for food safety. This process review will then be submitted to your regulatory authority for their approval. We also will refer you to other Cornell process authorities if you need help with non-dairy processes.
Food Safety Plan Review: Our team members are instructors of both HACCP and Preventive Controls for Human Food curricula, and are qualified to review or assist in developing your facility’s food safety plan. This service is useful for facilities who have an existing plan, are in the process of developing a new plan, or who are modifying their HACCP plan to meet the requirements of a FSMA food safety plan.
Gap Audit: Gap audits are used to identify areas for improvement in your food safety or quality system, and are a great way to prepare for a GFSI audit. Kimberly Bukowski, who is also an SQF auditor, visits your facility to evaluate both documentation and personnel/operational practices to help identify gaps in your systems.
On-site consulting: Extension personnel visit and consult with dairy processors to help troubleshoot or improve the food safety and quality of their products. Examples include visits to assess technical issues including quality, spoilage, or food safety concerns, food defense plan review, and special project consultation, and documentation review.
Milk Quality Improvement Program: Offers targeted fee-for-service microbiological and sensory testing to assist dairy processors with troubleshooting quality issues. Services include testing for groups of spoilage organisms, identification and subtyping, defect identification, and more.
Sensory Evaluation Center: Services include Consumer Acceptability, Preference, and Discrimination Testing. In addition, the program provides consultations in all matters related to sensory product testing: appropriateness of particular test methods, study sample size, questionnaire design, statistics, and analyses, sample blinding, and serving sizes, to name a few.
Institute for Food Safety COVID-19 Resources: This website is consistently updated with relevant resources and information for the food industry. Resources include information on upcoming industry office hours, weekly videos, templates and trainings, and updates on laws, regulations, and regulatory guidance.
On-farm Rapid Response Team: Offers timely assistance to NY dairy processors to troubleshoot farm related quality and safety issues
Alcaine Research Group (ARG) Dairy Lab: Quality control, waste reduction, and new product development opportunities
Food Processing Development Laboratory (FPDL): The Cornell Food Processing Development Laboratory (FPDL) is a licensed dairy plant in NY State and offers a unique food product development and manufacturing space that allows individuals and companies to perform research, develop new products, and start new food related businesses. Recognizing the diverse needs of industry, we offer an opportunity to utilize this facility under four different types of arrangements (see flyer here):

1. Product Testing: For small scale pilot research projects that can be completed in 100 days or less.
2. Cheese and Dairy Product Incubator: Designed for companies who do not have an existing facility, the FPDL can be used for initial product development and production.
3. Cheese and Dairy Product Incubator (Level II): Designed for companies who do not have an existing facility, but have done prior product development or for companies that have an existing facility but require an outside facility for specialized needs.
4. Contract Manufacturing and Product Development: For small scale manufacturing and pilot production (e.g. identifying processing issues, optimizing processes prior to large scale manufacturing, samples for market research).

If you need help with anything else that is not listed here, please also contact us – we probably have the resources to help you.

Recent Publications: January 2021

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Bach, K.D., D.M. Barbano, and J.A.A. McArt. 2020. “The Relationship of Excessive Energy Deficit with Milk Somatic Cell Score and Clinical Mastitis.” Journal of Dairy Science. https://doi.org/10.3168/jds.2020-18432.

Carroll, Laura M., Jana S. Huisman, and Martin Wiedmann. 2020. “Twentieth-Century Emergence of Antimicrobial Resistant Human- and Bovine-Associated Salmonella Enterica Serotype Typhimurium Lineages in New York State.” Scientific Reports 10 (1): 14428. https://doi.org/10.1038/s41598-020-71344-9.

Carroll, Laura M., and Martin Wiedmann. 2020. “Cereulide Synthetase Acquisition and Loss Events within the Evolutionary History of Group III Bacillus Cereus Sensu Lato Facilitate the Transition between Emetic and Diarrheal Foodborne Pathogens.” MBio 11 (4). https://doi.org/10.1128/mBio.01263-20.

“Effect of Weather on the Die-Off of Escherichia Coli and Attenuated Salmonella Enterica Serovar Typhimurium on Preharvest Leafy Greens Following Irrigation with Contaminated Water | Applied and Environmental Microbiology.” n.d. Accessed September 4, 2020. https://aem-asm-org.proxy.library.cornell.edu/content/86/17/e00899-20.

Gopirajah, Rajamanickam, Poonam Singha, Sumera Javad, and Syed S. H. Rizvi. n.d. “Emulsifying Properties of Milk Protein Concentrate Functionalized by Supercritical Fluid Extrusion.” Journal of Food Processing and Preservation n/a (n/a): e14754. https://doi.org/10.1111/jfpp.14754.

Harrand, Anna Sophia, Laura K. Strawn, Paola Mercedes Illas-Ortiz, Martin Wiedmann, and Daniel L. Weller. 2020. “Listeria Monocytogenes Prevalence Varies More within Fields Than between Fields or over Time on Conventionally Farmed New York Produce Fields.” Journal of Food Protection 83 (11): 1958–66. https://doi.org/10.4315/JFP-20-120.

Kapoor, Ragya, Apratim Jash, and Syed S. H. Rizvi. 2021. “Shelf-Life Extension of Paneer by a Sequential Supercritical-CO2-Based Process.” LWT 135 (January): 110060. https://doi.org/10.1016/j.lwt.2020.110060.

Lee, Michelle C., Younas Dadmohammadi, Chen Tan, and Alireza Abbaspourrad. 2020. “Mitigating the Astringency of Acidified Whey Protein in Proteinaceous High Internal Phase Emulsions.” ACS Applied Bio Materials, November. https://doi.org/10.1021/acsabm.0c00767.

Makki, Ghadeer M., Sarah M. Kozak, Katharine G. Jencarelli, and Samuel D. Alcaine. 2020a. “Evaluation of the Efficacy of Commercial Protective Cultures against Mold and Yeast in Queso Fresco.” Journal of Dairy Science, September. https://doi.org/10.3168/jds.2020-18769.

———. 2020b. “Evaluation of the Efficacy of Commercial Protective Cultures against Mold and Yeast in Queso Fresco.” Journal of Dairy Science 0 (0). https://doi.org/10.3168/jds.2020-18769.

Martin, N. H., P. Torres-Frenzel, and M. Wiedmann. 2020. “Invited Review: Controlling Dairy Product Spoilage to Reduce Food Loss and Waste.” Journal of Dairy Science, December. https://doi.org/10.3168/jds.2020-19130.

Reichler, S. J., S. I. Murphy, A. W. Erickson, N. H. Martin, A. B. Snyder, and M. Wiedmann. 2020. “Interventions Designed to Control Postpasteurization Contamination in High-Temperature, Short-Time-Pasteurized Fluid Milk Processing Facilities: A Case Study on the Effect of Employee Training, Clean-in-Place Chemical Modification, and Preventive Maintenance Programs.” Journal of Dairy Science 103 (8): 7569–84. https://doi.org/10.3168/jds.2020-18186.

Skeens, Jordan W., Martin Wiedmann, and Nicole H. Martin. 2020. “Spore-Forming Bacteria Associated with Dairy Powders Can Be Found in Bacteriological Grade Agar–Agar Supply.” Journal of Food Protection 83 (12): 2074–79. https://doi.org/10.4315/JFP-20-195.

Ubeyitogullari, Ali, and Syed S. H. Rizvi. 2020. “Production of High-Purity Phospholipid Concentrate from Buttermilk Powder Using Ethanol-Modified Supercritical Carbon Dioxide.” Journal of Dairy Science, August. https://doi.org/10.3168/jds.2020-18697.

Yoon, Ashton K., and Syed S. H. Rizvi. 2020. “Functional, Textural, and Sensory Properties of Milk Protein Concentrate-Based Supercritical Fluid Extrudates Made with Acid Whey.” International Journal of Food Properties 23 (1): 708–21. https://doi.org/10.1080/10942912.2020.1753768.

Detecting fluid milk post-pasteurization contamination using our modified Coliform Petrifilm method

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By Nicole Martin, PhD

Post-pasteurization contamination of fluid milk is a major contributor to premature spoilage. The microorganisms often responsible for this contamination are Pseudomonas and other Gram-negative bacteria. When introduced into fluid milk these Gram-negative bacteria grow rapidly at refrigeration temperatures and cause off-odors and flavors as well as body defect such as coagulation. In order to reduce post-pasteurization contamination, and thereby premature product spoilage, fluid milk processors need to be able to detect Gram-negative bacteria in fluid milk products. The standard method to detect Gram-negative bacteria in fluid milk uses Crystal Violet Tetrazolium Agar (CVTA), a traditional microbiological agar. While this method has been shown to detect Pseudomonas and other relevant Gram-negative bacteria causing post-pasteurization contamination in fluid milk, it is not accessible to many processors, especially those without the capabilities to make sterilized microbiological media in-house. Recently, the Milk Quality Improvement Program investigated the use of a modified Coliform Petrifilm method to detect Gram-negative bacteria in fluid milk. The results of this study “Short communication: Coliform Petrifilm as an alternative method for detecting total gram-negative bacteria in fluid milk” were published in the Journal of Dairy Science and showed that using Coliform Petrifilm incubated at 32°C for 48h prior to evaluation for any colony formation is an acceptable alternative to using CVTA to detect Gram-negative bacteria in fluid milk. This method is easily adoptable as many fluid milk processors already use Coliform Petrifilm and will allow for better detection of post-pasteurization contamination. Processors who wish to implement this method can read the full paper by contacting Nicole Martin at nhw6@cornell.edu.

Cornell Capabilities to Support Product, Process & Business Development

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Cornell Capabilities to Support Product, Process & Business Development

By: Rob Ralyea

Cornell’s FPDL

Cornell University’s Food Processing & Development Laboratory (FPDL) is housed within the Department of Food Science (College of Agriculture and Life Sciences) in Stocking Hall on Cornell’s Ithaca, NY, campus. The FPDL is a 6,000 square foot processing facility located adjacent to Cornell University’s dairy plant. It is a fully licensed dairy plant inspected by NY State Department of Agriculture and Markets.

Equipment available at the FPDL includes:

500 and 300 gallon semi-automated jacketed cheese vats
50 gallon semi-automated Double-O jacketed cheese vats
100 and 50 gallon vat pasteurizers
Large horizontal cheese press (88-2 lb wheel capacity)
HTST pasteurization system (with extended hold tube capable of up to a 4 minute hold)
5 gallon and 6 quart batch ice cream freezers
Yogurt incubation tanks (50 gallon to 400 gallon)
Automated Greek yogurt separator
Yogurt filler capable of filling 4 and 6 ounce cups (foil lid) with fruit on bottom
Niro atomizing tower spray dryer
Virtis freeze dryer
Pilot evaporator
Microthermics unit for prototype development for higher temperature pasteurization modeling

Cornell’s FPDL provides education, training and technical assistance for the production of value added food and dairy products throughout New York State. The FPDL serves as a statewide center for food and dairy processing education and training, product development and cutting-edge food processing research. It is a key resource supporting the long-term sustainability of value-added agricultural businesses (and their suppliers) across New York State. The FPDL is integrated within the Food Science program complex, in Stocking Hall, which is completing a four-year State University Construction Fund rehabilitation. As such, our goal is to help promote and grow dairy processing opportunities in New York State and to provide opportunities for agricultural producers to develop and market value-added products. The successful establishment and expansion of local, value added products also encourages the creation and expansion of other local business (farmer’s markets, restaurants, agri-tourism, marketing, etc.).

To facilitate dairy start-up companies and promote growth in the dairy industry, we offer a dairy processing incubator program that has been in place for the last 18 months. To qualify, you must be in NY State and be a small dairy business or be aspiring to start a business in dairy processing in NY. This is not an open-ended proposition, as you must sign agreements with Cornell University indicating your desire to start and grow a dairy processing-type business. You must have an approved business plan in place within 3 months of starting and must be planning to move out of our facility into your own facility within 12-18 months. You also provide the labor (although we do have Food Science students/interns that are available on certain days that we use to assist in production), and for set fees, we provide equipment to use. We will help with small product development projects provided you already have the concept. If you want us to do full blown product development, fees increase accordingly.

We also provide contract manufacturing support to start-up companies as well as established manufacturers developing new and innovative products. Examples of product development and research projects supported by the FPDL include dairy-based puddings, drinkable yogurts, fermented dairy beverages, flavored egg nog and other dairy related products. Because of our smaller scale equipment, our facility is ideal for manufacturing test runs of new formulations or producing consumer or shelf life testing type products on a relatively small scale, yet still mimic real production.

If you are interested in any of these programs, or would like more information on the facility, please contact Rob Ralyea at rdr10@cornell.edu.

The Acid “Whey” – A New Hero’s Journey?

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By: Samuel D. Alcaine
Previously published in Dairy Foods, May 2018

To the yang of every superhero’s rise, there is the yin of an equally formidable foe. Batman and the Joker, Spiderman and the Green Goblin, and in the fermented dairy aisle, Greek yogurt and acid whey.

Greek yogurt’s decade of protein-powered growth in American refrigerators has been hounded by stories of the production of “toxic” acid whey and its potentially nefarious impact on the environment. But is acid whey really the villain it’s been made out to be? Or is it just misunderstood?

Understand the enemy

Acid whey’s bad rap starts with its name, which makes it sound like a spill would burn a hole through the floor. But when it comes to food, is it really deserving of its acidic moniker?

Coming in at a pH of 4.5 to 4.2, acid whey’s acidity compares to beer. Juices, ciders, wines and kombucha are actually much more acidic, below 4.0.

The acidity does have ramifications for some processing such as drying, but the lower pH also means that many of those important dairy minerals have solubilized; thus, acid whey is rich in calcium, magnesium and phosphorus.

Due to the extended pasteurization in Greek yogurt production — which denatures whey protein, trapping it in the casein gel — acid whey has very little protein. But it is high in lactose, a valuable carbohydrate. You see, young Skywalker, there is still good in acid whey.

Acid whey is typically loaded into a tanker and hauled off for use as a mineral additive to soil, a nutritional component for animal feed or an energy substrate for anaerobic digesters. This inherently involves the environmentally unfriendly transport of a lot of water.

Membrane filtration technologies have come to the rescue, allowing for the concentration of acid whey to minimize the carbon footprint of transportation. Membrane technologies haven’t stopped there; researchers at universities across the country have been optimizing and cascading these technologies to tease out each of the components in acid whey — lactose, minerals and lactic acid — so their value can be captured and put to good use.

Toast a hero

Lifting a glass of whey for an afternoon recharge has never been popular in the United States, but whey-based products have gained traction in Europe. There are plenty of signs that the American taste palate is changing, too. Growth in beverages such as kombucha, vinegar tonics and switchel show rising interest in sour good-for-you propositions, where acid whey could naturally find a home.

We are beginning to see action here. White Moustache, an artisanal strained-yogurt producer in Brooklyn, has a line of probiotic tonics and just launched popsicles from its acid whey. Perhaps all acid whey will need is a new superhero package and creation story.

I’ve heard stories of Dr. Kosikowski’s whey wine, but sometimes great ideas are too early for their times. Forty years later, we are beginning to see whey-based vodkas hit the global market, including those from Black Cow in the U.K. and the Hartshorn Distillery in Australia. Universities are also researching whey-based distilled spirits, and my lab is exploring acid whey-based sour beers.

In this era of new environmentally focused, health-conscious dairy consumers, the upcycling of acid whey represents a natural frontier. Rather than a “toxic” poison, it’s full of bioavailable minerals and potential prebiotic and probiotic components. Perhaps it’s the magic elixir for creating a new superhero in your portfolio.

Link to original article is here.

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Category Archives: Dairy Research