Dairy Foods talked to:

Dan Belina, rtech laboratories, microbiology supervisor, Land O’Lakes Inc.
John Faragher, national accounts manager - preservation, DSM Food Specialties
Zoe Grosser, application solutions director, PerkinElmer Inc.
Kevin Habas, market development manager - pathogens, 3M Microbiology
Jacquelin Page, president, Page & Pedersen International Ltd.
Bob Salter, vice president regulatory affairs, Charm Sciences
Scott Scdoris, global business development manager - beverage, Celsis
Julie Tan, product manager, BioControl Systems
John Urh, process product manager, CEM Corp.
Fred Weber, president, Weber Scientific
Gary White, market development manager - dairy and beverage solutions, Neogen Corp.


President Obama and his administration are taking a comprehensive approach to developing an improved national food safety system. Currently, the White House Food Safety Working Group, being led by Agriculture Secretary Tom Vilsack and Health and Human Services Secretary Kathleen Sebelius, is in the preliminary stages of determining the status of safety critical points monitored by the nation’s farmers, food manufacturers and retailers. For the most part, dairy, being a highly regulated category, is in good shape, as compared to other commodities and prepared and packaged foods.

“The Working Group will be an important tool for gathering ideas as to how we can strengthen the food safety system to be more accountable and accessible to the public it protects, flexible enough to quickly resolve new safety challenges that emerge, and able to meet the robust needs of our rapidly changing world,” says Vilsack.

Sebelius adds: “Families have enough to worry about. You shouldn’t have to wonder if the food you buy at the grocery store is safe. Our Working Group is working hard to modernize our food safety system and protect the American people.”

Dairy food processors should ask themselves if they are testing enough, as well as accurately. Are tests up to date and properly calibrated? Are technicians trained? Are samples being obtained properly and often enough? Processors should be proactive and make sure they have the best plan in place to ensure the safety - and quality - of their products.

Dairy Foods talked with 11 experts in the lab testing field to learn about the status of the business, and what the future holds. Here’s what they said.


Dairy Foods: What are the most vulnerable “safety” points in dairy foods manufacturing?

Page: Within the dairy processing plant, there are several critical safety and quality control points. Some tests (i.e., antibiotic, somatic cell, adulteration, composition, etc.) are performed on each tanker delivering milk and also for each supplier on a regular schedule. Other tests (i.e., allergen detection, vitamin levels, etc.) are performed only within the context of production at regularly scheduled intervals. A few tests are performed throughout the dairy supply chain (i.e., milk composition, alkaline phosphatase, pathogens, etc.) to ensure quality, safety and sound nutritional value from the farm gate to the customer’s plate or glass.

Salter: Proper sanitation is vital to ensuring food quality and safety. If not removed by thorough cleaning, allergens, microorganisms and food residues can affect product safety and shelf life, which can lead to ingredient cross-contamination and recalls. ATP bioluminescence testing has become the de facto standard for rapidly measuring surface cleanliness and evaluating the effectiveness of sanitation programs. Immediate results enable corrective action before potential problems occur.

Chemical residues in dairy products are also a growing consumer concern. Natural toxins, such has aflatoxins are produced by molds that grow in grains and hay pre- and post-harvest. Dairy manufacturers monitor incoming milk for aflatoxin as a precaution.

Antibiotics may also be used in animal health practices and these should not pass into the milk supply. In addition to potential health effects, antibiotic residues may cause economic losses if they become inhibitory to cheese or yogurt cultures. Slow-setting cultures may lead to off flavors and shorter shelf life.

Faragher: The presence of antibiotic residue in milk is always a concern. Even at the best run farms, accidents can happen. That is why the industry has a strong program for testing milk to insure that it is free of antibiotic residues. The tests used to detect the presence of antibiotics in milk are divided into two basic classes. There are fast, reliable tests based on antibody/antigen reactions. They are generally limited to detecting a single antibiotic or a class of antibiotics. The other technology uses the growth of a special strain of bacteria that is very sensitive to antibiotics. These tests can detect a broad spectrum of antibiotics from many different classes; however, they generally take two to three hours to complete.

Weber: Pasteurization is the most-effective microbiological safety step for dairy products. Testing for alkaline phosphatase is the recognized method for confirming the completeness of pasteurization. The test is based on the detection of the phosphatase enzyme, a constituent of raw milk, which is destroyed by pasteurization. Sophisticated electronic systems can detect as little as 0.003% of raw milk contamination.

Also, standard plate counts and coliform tests are run on raw as well as pasteurized milk and milk products. The standard plate counts check for overall viable bacteria and gives valuable information about quality throughout the process, from receipt to finished product. The presence of coliforms has also long been a critical indicator of faulty pasteurization or post-pasteurization contamination, as well as inadequate plant sanitation. Along with traditional standard methods, convenience methods such as pectin-gel prepared media methods and film-type petri plates have rapidly grown in popularity because they save dairy labs time, labor and money. Both methods have also contributed to enhanced reliability and reproducibility.

Habas: Because the dairy processing environment is typically very wet, Listeria monocytogenes contamination is always an issue. Many plants monitor incoming receiving bays, areas where walls and floors merge that are difficult to dry thoroughly, central drains and non-food contact equipment surfaces. A  prominent method used for monitoring indicator bacteria in dairy plants is a rehydratable film that incorporates dyes and an auto-counter for enumeration.       

Belina: Pathogens such as L. monocytogenes, Escherichia. coli,  Bacillus cereus and Staphylococcus aureus are also usually tested for. The initial screening for these pathogens is typically done with rapid screening procedures and usually takes 24 to 48 hours to yield a negative or presumptive positive result. Since all rapid screening methods yield a certain rate of false positive results, all presumptive positive tests are normally confirmed, or not confirmed, with traditional culture test procedures. The traditional culture test procedures are reliable but much more time consuming.

Scdoris: The longer shelf life of ultra-high-temperature (UHT) milk depends on the aseptic containers staying free from microorganisms. ATP bioluminescence-based tests allow a manufacturer to confirm the presence or absence of microbial contamination in 24 to 48 hours compared to three to five days using traditional plating methods.

White: Allergen testing remains a critical concern for all food manufacturers. As production cycles tighten, the need to detect allergens following cleaning cycles is critical, whether it is fluid milk being produced on the same equipment as other beverages such as soy-based products or juices, teas and waters, or whether it is ice cream products or other value-added products. Many companies perform allergen verification tests to assure the cleaning cycles are meeting expectations, and that finished product is not contaminated with unintended ingredients.

Grosser: The measurement of metals for nutritional labeling is commonly done using inductively coupled plasma (ICP) optical emission spectroscopy. This is also a good technique for the screening of metal contamination and can be extended to lower concentration limits through the use of ICP mass spectrometry. These techniques have sped up analyses and can look at a variety of elements at one time, providing confidence that contamination has not taken place at any point throughout the process.


Dairy Foods: Product composition tests are more of an indicator of quality than safety, but equally as important to processors. How have these tests changed since the turn of the century?

Belina: The trend over the last several years has been to replace traditional methods with infrared spectroscopy instrumentation. The advantage of this technology is that you can obtain results from multiple components on the same sample in a matter of seconds. For example, you can scan a milk or whey sample and obtain total solids, fat, protein and lactose results simultaneously in about 30 seconds. This enables the plant operator to make immediate adjustments to a process. This is not possible with traditional wet chemistry methods that often take several hours to complete. 

Infrared instrumentation requires calibrations that are built with wet chemistry data. Multiple samples are scanned and the wet chemistry data is entered into the instrument. Software equipped with instrumentation uses all of the entered information to build a calibration. Typically each sample type needs its own calibration and requires anywhere from about 12 calibration samples for liquids, such as whey and milk, which often use mid-infrared instrumentation, to 100 or more calibration samples for solids, such as cheese or butter, which often use near-infrared instrumentation.

Urh: Fats and solids have historically been determined using lengthy methods that rely on solvent extractions. A new system using a combination of microwave and nuclear magnetic resonance technology provides results in minutes and uses no solvents.

Protein has historically been determined using the Kjeldahl technique, which takes three to six hours and uses boiling sulfuric acid. This test measures nitrogen, with the value converted to protein using a mathematical formula. A new patent-pending system eliminates the use of chemicals and relies on protein-tagging technology, which identifies, tags and measures only the amino groups found in proteins. Fillers and other sources of non-protein nitrogen are ignored.

Tan: To ensure milk is fresh, a test for L-lactic acid is used. Lactic acid is a product of lactose degradation, so if there’s a high level present, this is an indication of degradation. Normally, fresh milk should not contain more than 30 ppm of lactic acid. In most countries, other commonly monitored parameters include urea, lactose and glucose. Urea is measured as part of the milk payment scheme and is a quality indicator. Urea can be measured using the proprietary technology of differential pH. The sample is loaded into the instrument, which contains microelectrodes capable of measuring small changes in pH levels. An enzyme is added to the sample to drive the reaction to completion, raising the pH level. The rise in pH levels allows for the determination of the urea concentration. Using this same proprietary technology, L-lactic acid, lactose and glucose can be measured.

Weber: Ultrasonic high-frequency sound waves have been used for years to discriminate and quantify basic mechanical, structural or compositional properties of solids and liquids in a wide range of diagnostic and monitoring requirements within the medical community.  This technology is increasingly being used in a growing number of applications within the pharmaceutical, food, dairy and other industries.

Ultrasonic milk analyzers are being used by a growing number of dairy labs for dependable multi-parameter test results for fat, solids, solids-not-fat, protein, density and lactose. In 85 seconds it provides results for raw or processed milks. Compact, lightweight, portable and reliable, ultrasonic analyzers provide results with similar accuracy to bench chemistry but in a fraction of the time. Features compare favorably to infrared instruments that typically cost five to 15 times as much.

Ultrasonic material analysis is based on a simple principle of physics: The motion of any wave will be affected by the medium through which it travels. Thus, change in one or more of four easily measurable parameters - transit time, attenuation, scattering and frequency contact - associated with the passage of a high-frequency sound wave through a material can be correlated with certain compositional parameters. In other words, these waves explore or probe intermolecular forces, providing information regarding the interior of a sample. 

Page: Another interesting introduction has been the world’s first compact and truly portable freezing-point cryoscope. Freezing-point cryoscopes provide accurate information about added water content in milk and fluid dairy products. A recently released compact freezing-point cryoscope is able to super cool the sample, institute a freeze-pulse to cause the sample to return to its normal freezing point and measure that plateau in accordance with recommended reference methods while operating from either a battery or standard electric current. 


Dairy Foods: What lab tests are available to project and/or monitor shelf life?

Habas: There are two traditional shelf life predictor test protocols that fluid dairies employ: the Moseley keeping quality test and the preliminary indication method. Both use total plate count growth media as the base test. The total bacterial growth on the plate after a specified incubation period “predicts” the shelf life of the product based on a table of values.

Salter: A new generation microplate luminescence system rapidly predicts spoilage in shelf-stable and extended shelf-life dairy-based products. Samples are stressed at elevated temperatures, which allow remaining post-process bacteria to multiply. Then a quick screen is done to identify bacteria levels. Faster and more sensitive than conventional microbiological methods, this system enables faster product release from warehouse, reducing process line downtime and providing more time for remediation.

Weber: It is important to properly sample milk for predictive shelf life testing. A patented aseptic sampling process can be installed at many points in either lines or tanks. Sterile self-sealing rubber membranes fit into specially designed stainless steel fittings. An aseptic sample is obtained through the use of a single-use sampling bag. This bag has tubing and a needle attached, which allows a sample to be taken over a five- to 10-minute time period. These aseptic samples are then used to analyze the microbial spoilage of milk.

Tan: L-lactic acid is a general indicator of milk freshness and its level can be used to project shelf life. In cheese, glutamic acid, a product of protein degradation, can be monitored.  For dried milk products, the ratio between lactose/D-glucose is measured so that the product can remain stable on shelves. 

Scdoris: For UHT products (dairy or juice), shelf life is ensured by the product being free from microbial contamination. Any contaminants present at the time of packaging will have an extended time to grow and, in the case of aseptic products, an elevated temperature, since refrigeration may not be required. As a presence/absence test, an ATP bioluminescence assay is the ideal application to ensure that the final product is free of microbial contamination.


Dairy Foods: What is in the future for lab tests used in the dairy lab?

Scdoris: Suppliers are working to develop increasingly sensitive tests to reduce the incubation time currently needed for end-product testing. At the same time, such a solution must be able to deliver the high-volume throughput required by large-scale processing facilities at an affordable price.

White: Tests will continue to become more accurate predictors of safe products for consumers. It can be anticipated that automation will play an important role, and time to results will be critical.

Salter: In the future, the dairy lab will play a greater quality assurance role as tests will be so simple and fool-proof that the production team will do most of the testing. Of course there will always be a need for experts who understand the science and testing procedures, but tests will be performed in the field or on the production line rather than in a specialized lab.

Grosser: Near infrared spectroscopy has been used for many years to quantify dairy products for fat and protein content. With recent food safety issues, work is underway to evaluate this technique for rapid contaminant detection and identification. Technology will continue to advance to smaller, more intelligent packages, making it easier to get more information productively. Public opinion drives much of regulation and I expect we may see additional regulations based on the problems seen in the recent past with contamination and adulteration.

Page: I once asked the director of the Swedish Dairies Association what he would like to see in automated testing. He stated that he would like an instrument that could test all parameters with the utmost of accuracy and ease, with the most comprehensive ranges, at a minimal cost for the instrument and no cost per test. At that time, some 20 years ago, that description sounded like more whimsy than reality, but with the paradigm shifts in scientific advancement over the past decades, that whim now rings more of reality than fantasy. 

It is important to note that dairy labs exist the world over and resources, including training and education, are quite diverse within this environment. So in developing dairying nations, practical tests will need to coexist with comprehensive, sophisticated, state-of-the-art instruments that will be able to deliver results for all parameters with the utmost of accuracy and most comprehensive ranges at a cost that the market will bear.

“Since we formed our farmer-owned cooperative more than 20 years ago, we have striven to provide our customers with the most nutritious and best-tasting organic food that is produced under the strictest food safety standards,” says George Siemon, one of the founding farmers and CEO of Organic Valley, LaFarge, Wis.

Louise Hemstead, one of the cooperative’s dairy farmers and COO of Organic Valley, adds: “We have a comprehensive quality assurance program in place that monitors quality throughout our product’s life cycle – from the farm to the plate. We have always made our protocols available for review to any customer, producer, distributor or retailer who asks for it.”

To achieve quality assurance, Organic Valley has a comprehensive program led by a team of 14 professionals that ensures its products are in compliance. Organic Valley’s products are processed and packaged at their facilities and other co-processing plants throughout the nation. The facilities and co-processors are audited annually and inspected by a full-time quality auditor as well as a certified third-party auditing firm and USDA accredited organic certifier to ensure that they are compliant, or exceeding, governmental food safety, customer requirements, product and environmental testing, and any additional quality standards required by Organic Valley.

Organic Valley tests its raw materials for quality at the farm, monitors the trucking, and then tests again at the receiving destination. Once the raw materials arrive at the processing plant, Organic Valley’s contracted co-processors perform tests including, but not limited to, microbial, analytical, sensory and environmental monitoring. In addition, its packaging materials held at the plants are monitored by Organic Valley staff to ensure top-quality packaging. 

 When the processing facility has packaged a finished product, Organic Valley’s logistics team coordinates and manages the transportation, storage and distribution, ensuring strict temperature parameters are enforced at the warehousing and trucking levels. The processing facility also retains samples from each product lot, which are reviewed as the product ages to ensure quality is maintained throughout the product’s life span.

For a complete detailed description of Organic Valley’s Quality Assurance Program, visit www.organicvalley.coop/our-story/transparency..