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Is it really necessary to test at a higher dilution for pathogen testing?
By: Carol Sivey – Microbiologist
Why do laboratories sometimes require high dilutions when screening for pathogens like Salmonella and Listeria?
Spices and flavorings often contain essential oils that inhibit bacteria, including pathogens, from growing to detectable levels. Furthermore, in the case of spices and herbs, the concentration of inhibitory substances can vary for the same spice depending on the region of the world and the season of the year in which it was grown. This can create a challenge for pathogen detection in these materials. If bacterial growth is not inhibited, target pathogens can usually grow to 106 /mL or higher in an overnight enrichment medium, with most next-day screening platforms requiring a concentration of at least 103 /mL or higher for accurate detection. If these levels are not achieved, a false negative result is possible.
This inhibitory activity of spices, herbs, and flavorings can be overcome by diluting the sample beyond the standard testing dilution, which would allow for a more favorable environment for bacterial growth.
Often, for their intended applications, spices and flavorings are used in foods at relatively low levels and higher testing dilution mimics the level that these materials are present in consumer goods. At these levels, their inhibitory agents can be diluted beyond toxic levels and pathogens can grow into a threat to food safety. The laboratory must therefore conduct the screening at a concentration that has been proven to allow for the growth of Salmonella and Listeria.
NQAC Dublin has an on-going pathogen verification program. Trial dilutions of a matrix are spiked with low levels of Salmonella or Listeria, tested per respective protocols, and the lowest dilution that achieves recovery becomes the test dilution for that matrix. We currently have over 500 different matrices in our verification database.
Is there any research into developing enrichment medias to overcome inhibitory substances?
Yes, and our technical team is actively participating in these studies! We understand that high dilutions of up to 1:1000 or higher, significantly raise the cost of food safety. Our team recently participated in an ISO study to evaluate neutralizers to enhance recovery of Salmonella from spices. Five neutralizing agents were tested for efficacy in oregano, cinnamon, and cloves. The spices were spiked with low levels of stressed Salmonella and recovery was detected culturally based on ISO 6579-1:2017. One item, activated charcoal, proved effective in reducing oregano dilutions from 1:100 to 1:20, cinnamon dilutions from 1:200 to 1:50, and cloves from 1:500 to 1:100. While not yet validated and not in routine use at our laboratory, we hope to further these studies with a media vendor or another laboratory to work toward full validation. The study was summarized in a poster presented at the 2020 Virtual IAFP Annual Meeting in late October: Neutralization of Inhibitory Substances in Oregano, Cinnamon, and Cloves for the Recovery of Salmonella. C. Sivey, D. Tomas, A. Finnarn, and K. Sow.
So yes, it really is necessary sometimes for pathogen testing to require higher dilutions, especially when it comes to inhibitory matrices like spices, herbs and flavorings. The higher dilutions are proven to achieve the most accurate results and lessen the potential for a false negative result being reported for your product.
Ensuring accurate results, especially when it comes to pathogen testing, is the highest priority for NQAC Dublin. It’s an important responsibility to ensure that the food, beverages, and ingredients tested in our facility are held to the highest standards. It’s part of our responsibility to help protect both consumers and food industry businesses. To that end, we hold all the products we test to the utmost safety and quality standards.
If you have more questions or would like to discuss our verification programs and your product needs. Contact us and we’d be happy to answer any questions you have.
Selecting the appropriate method is critical for ensuring accurate results for your premix sample. Here are some steps to guide you through appropriate test selection:
By: Jessica Hanson – Chemist
When selecting testing for a sample, it is important to identify a few aspects about the sample matrix in order to help ensure your results are accurate and timely.
- Is the sample a premix or finished product?
A premix is a blend of micronutrients (vitamins and minerals) used to fortify and enrich food products; thus, its concentration of micronutrients is very high. A finished product typically has a much lower concentration of micronutrients.
Determining which category your sample falls into is an essential first step in selecting the appropriate method for testing and will help ensure results are issued as quickly as possible. If you are unsure, supplying the laboratory with accurate estimated levels for the vitamin in question will help the laboratory in updating the testing, if necessary, prior to performing any analytical work.
As an example, suppose the lab receives a sample requesting Vitamin B12 testing. The method selected for testing is intended for products with lower concentrations of vitamin B12 and no estimated levels are supplied to the lab prior to testing. The laboratory preps the sample for the finished product B12 method and performs the testing, however when the results are generated it is found that they are outside of the calibration curve1 due to high concentration of B12 in the sample. The sample will need to be re-prepped and tested using the premix B12 method, which delays the issuance of final results.
- What form of micronutrient is present in the sample?
Providing the form of the micronutrient in the sample can give the laboratory valuable information when determining if the method selected for testing is most appropriate for the sample type. In certain instances, the form of vitamin present in the sample may require testing under a different methodology.
Going back to the Vitamin B12 example, the sample being tested contained methylcobalamin but this information was not provided prior to testing. The laboratory did the re-prep and retest using the premix method for B12 based on the over the curve results obtained during the initial round of testing. However, this time the results are coming back as not detectable. In this case, the sample should have been tested using the finished product method that can account for methylcobalamin with additional dilutions2 added during prep due to the increased concentration of B12 in the sample. The sample will need to be re-prepped a third time and retested, resulting in additional delay in result reporting.
As you can see, identifying if the product is a premix, providing estimated levels, and specifying the form of micronutrient can reduce the time it takes to get sample results as the correct method can be selected during the initial analysis and any necessary dilutions can be performed.
NQAC Dublin offers a wide variety of vitamins methods covering many different product types and ingredients. If you desire help in selecting which test(s) are best for your needs, our Customer Service team (email@example.com) is available to provide information and assistance.
What could be worse than opening the refrigerator only to discover food covered in furry white (or blue, or green) mold?
By: Ernest Capraro – Chemist
Although the visual is repulsive, far worse is unknowingly eating food containing mold and the toxins that certain varieties produce.
Mycotoxins (the prefix “myco” comes from Greek, and refers to fungi/mold) are pervasive and represent a constant threat to the world’s food supply. The mycotoxins they produce remain even if the fungus is killed. These toxins vary in effect. With its readily apparent symptoms, Deoxynivalenol (DON) is commonly known as vomitoxin, presenting an acutely severe health risk. On the other hand, Aflatoxin B1 is the world’s most potent naturally occurring carcinogen, posing a significant chronic risk. The USDA has made available a detailed mycotoxin guide which includes the health effects of a wide number of mycotoxins.
Mycotoxins are harmful to both humans and livestock. Monitoring is fundamental to protect the integrity of the food supply network, and the health of consumers. Nations around the world maintain regulations limiting the mycotoxin content in various foods. Limits vary across borders, but one constant is that the strictest (lowest) limits are applied to infant food and formula. Because food production is a global industry, keeping abreast of regulations is key. A user-friendly resource can be found at mycotoxins.info, providing regulations by region and nation.
A mycotoxin monitoring program should be driven by the need to comply with regulations in target markets, and a thorough risk assessment. While the design of such a program is beyond the scope of this article, recognizing some of the biggest threats is not difficult. Consider that fungi will primarily grow in one of two places – in the field, or in storage. “Field mycotoxins” are those that are produced by fungi that grow on live crops. In the case of grains or nuts, this means that the fungus will already be present at the time the seed starts to form, and ultimately becomes trapped inside. “Storage mycotoxins” grow under storage conditions that favor fungal growth. Uncontrolled high humidity or other dampness, especially with minimal air circulation, increase this risk.
Field mycotoxins are most commonly observed on grains. In the Americas, there is a tendency to see DON, Fumonisins B1 and B2 (FB1 and FB2), and Zearalenone (ZEN / ZON) in grains. Corn, in particular, is frequently contaminated by higher levels of these toxins. Wheat is another commonly contaminated grain, while rice typically exhibits lower levels. In nuts, it is most common to observe the Aflatoxins – B1, B2, G1 & G2. The largest Aflatoxin contaminations tend to occur in pecans. Since mycotoxins are not easily destroyed, any foods prepared from these grains or nuts is also at risk. For instance, corn oil could easily contain ZEN.
Storage mycotoxins threaten products that may be stored for a period of time before processing or making it to market. Aflatoxins B1, B2, G1 & G2 and Ochratoxin A (OTA) are the primary storage mycotoxins. Cocoa powder or coffee beans are examples of materials susceptible to fungal growth during storage. Grains, too, may suffer fungal attacks while stored.
One significant mycotoxin isn’t directly produced by a fungus. When a cow eats grass, hay, or other feed that is contaminated with Aflatoxin B1, the cow is able to metabolize some into a new form that is called Aflatoxin M1. The “M” refers to milk, in which the mycotoxin can be found. As such, dairy products are typically monitored for Aflatoxin M1. Most importantly, infant formula needs this testing, since babies are among the most vulnerable to mycotoxins.
NQAC Dublin has testing options for these mycotoxins and more. If you have specific mycotoxin testing requirements, or desire help in selecting which test(s) are best for your needs, our Customer Service team (firstname.lastname@example.org) is available to provide information and assistance.
Protect your Customers and Business with Environmental Monitoring
By: Andrea Chmelar – Environmental Monitoring Specialist, Microbiology Supervisor
Pathogens are everywhere and often show up when you least expect it. They have the potential to cause significant damage to your brand, customer trust and, most importantly, consumer health. A well-designed Environmental Monitoring (EM) Program can help mitigate this risk and is an essential component to a robust Pathogen Monitoring Program (PMP). Developing strong environmental monitoring is a journey and takes a lot of work but, when done correctly, it can positively impact your bottom line.
EM provides insight into the microbial population of your factory and verifies that your food safety management systems are working as intended. It should provide you with early pathogen detection and is required by the Food Safety Modernization ACT (FSMA) if you have product that is exposed after a kill step and before packaging. To be clear, EM does not prevent pathogens from entering your product – this is what your hygienic controls and pre-requisite programs are for, but EM will tell you how well you are executing these programs.
There are several components to a healthy EM program:
- site selection and frequency – based on risk and proximity to production line
- tool selection – based on the product manufactured in the factory, sanitizer used in cleaning procedures and product specifications
- data management – accurate records of site results to allow to trending and analysis
- solid corrective action processes – provides guidance for action in the event of a positive pathogen result or out of specification hygiene indicators
- strong training and coaching – your program is only as strong as the training/coaching program supporting it
Remember, having an excellent Environmental Monitoring program takes practice and vigilance. Your program is a living document that may need to adapt to the season, a specific product type, or different areas of your facility.
If you would like learn more about the components of a strong EM program, please join us for our on-demand webinar with Food Safety Magazine. Or if you are looking to revamp your current program or if you need to set one up, contact us today and our quality professionals will discuss your needs and set you on the right path: email@example.com
New Methods Available at NQAC Dublin
On 8/10/2020, NQAC Dublin is excited to announce that we will be launching five new additions to our analysis portfolio. Please find details about each new method below and please reach out to us at firstname.lastname@example.org if you have any questions.
Quarternary Ammonium Compounds (QAC)
Quarternary Ammonium Compounds is verified and will be available as LI-00.044 Quarternary Ammonium Compounds by LC-MS/MS. This method analyzes for seven quarternary ammonium compounds including DDAC, BAC-8, BAC-10, BAC-12, BAC-14, BAC-16 and BAC-18) in foods.
- Validated matrices include:
- Powdered Infant Formula (milk, powder) and fresh milk
- Fresh fruit and vegetables (high water content vegetables)
- Validated matrices have a reporting range of 0.010-1.5 mg/kg
Volatile Organic Compounds
Volatile Organic Compounds (VOC) in drinking water is verified at our location and will be available as EPA 524.2 by GC-MS. The method is applicable to finished drinking water, raw source, or drinking water in any treatment stage.
- A full list of compounds covered by this method is available by request
Osteopontin in Infant Formula
Osteopontin (OPN) is a highly glycosylated, phosphorylated, acidic whey protein that could potentially play a role in infant immunity and development. It is present in human milk at approximately 138 mg/L; a level around eight-times that of bovine milk (18 mg/L). The protein has been implicated in a wide number of biological processes including cell survival, bone remodeling and immune modulatory functions.
- Osteopontin (OPN) in infant formula and growing up milk by UPLC-MSMS is available under NQA-55.0002
Lutein added to Carotenoids Method
Lutein is in the family of carotenoids found in common foods including spinach, peas, and broccoli. It is a structural component of the eye, potent antioxidant, and will be available for testing under the expanded carotenoids method LI-00.683-2 by HPLC-UV.
- LI-00.683-2 has been validated for testing on Infant Formula and Adult Nutritionals
- Results will be issued with a range of 20.0-1000 µg/100 on these matrices
Food Nutritional Fortification Substance Lactoferrin
As our final new method announcement, we will now offer a method for the analysis of Lactoferrin listed as a Food Nutritional Fortification Substance, GB 1903.17-2016.
This standard applies to food nutritional fortification substance Lactoferrin prepared using milk and milk products as raw materials through separation, sterilization, extraction, refinement and drying.
Have you ever experienced a foreign body incident in your factory? Or have your customers ever reported finding one in your product?
By: Daniel Smieszek – Technical Services
When purchasing food products, consumers expect products that are high quality, safe and free from any unexpected foreign bodies. A useful working definition of a foreign body is “an object which can be seen by the unaided eye or felt in the mouth, and which the consumer perceives as being alien to the food” . This may include common materials such as metal, plastic, glass, stones and wood. These unexpected materials are typically inadvertently introduced during processing, manufacturing, packaging or shipping. Consumers may also notice other foreign bodies that are part of the food ingredients but undesirable, such as plant leaves/stems, seeds and even scorched product.
Food manufactures must put controls in place to prevent foreign bodies from entering the product but even with safeguards in place, consumers still find them on a frequent basis. A foreign body incident can have huge impact on consumers and can even lead to product recalls. In 2019, the FDA estimated that 6% of recalls were due to foreign bodies . In addition, Food Safety Modernization Act (FSMA) requires that physical hazards are identified and preventive controls are put in place.
It is important to identify the foreign body quickly and accurately to attain root cause and prevent recurrence. Many foreign bodies can visibly look similar to the unaided eye so it is critical to have the proper technology to support identification.
We use Fourier Transform Infra-Red Spectroscopy (FTIR) and X-Ray Fluorescence Spectroscopy (XRF) technologies to help identify glass, plastic, metal and organic materials. These technologies generate a customized report that includes microscopic view of the foreign material and techniques are used to help identify or compare your foreign bodies.
Here are some additional details on the two technologies we use:
NQA-00.8321 Material Characterization by FTIR
The use of IR radiation to determine chemical bonds & functional groups creating a molecular fingerprint. This fingerprint is compared to known references for identification.
NQA-00.8325 Material Characterization by XRF
The use of X-rays to identify elemental composition for metal & glass. Elemental percentage is used to determine potential metal alloys for the foreign body.
Do you need to know if that white plastic is coming from your factory ? Would you like a custom library of potential sources of foreign material in your facility?
We offer identification of foreign materials as well as mapping of production lines and can develop a custom material characterization library to assist with your management of foreign bodies. By preparing your facility for a foreign body incident, if one occurs, you will have the ability to react quickly to identify the source and prevent any further disruptions and potential losses.
If you need assistance with foreign body investigations or characterizing your consumer complaint samples, please contact our Customer Service team at email@example.com for more information.
FDA: New Era of Smarter Food Safety Blueprint
The FDA recently launched their New Era of Smarter Food Safety Blueprint and we are excited to see where the future of food safety leads us. Their approach outlined in the blueprint shares the FDA’s vision over the next decade of their food safety goals.
A modern approach to food safety is outlined in the blueprint with goals of enhanced traceability and predictive analytics. With more transparency, we will have the ability to quickly respond to foodborne illness outbreaks and reduce food contamination. Developing stronger food safety cultures is also one of the core elements of the blueprint.
As our country has navigated through the COVID-19 pandemic, experts have learned many lessons throughout and will use their newfound knowledge to create a safer food system for the future. It will be more important than ever for transparency and partnerships between public health, industry and government authorities as we move into the future of food safety. FSMA has provided the groundwork for the FDA blueprint and moving into the next decade, we’ll see new foods, products, technologies along with established science and risk-based protections guide changes for a safer food system.
The below are the four Core Elements outlined in the blueprint:
- Core Element 1: Tech-Enabled Traceability
- Core Element 2: Smarter Tools and Approaches for Prevention and Outbreak Response
- Core Element 3: New Business Models and Retail Modernization
- Core Element 4: Food Safety Culture
For the full blueprint and all the details, visit: https://www.fda.gov/food/new-era-smarter-food-safety
We look forward to being part of the future of food safety and are here to help support your business in any way we can. Let us know how we can help!
How accurate are your product cooking instructions?
By Brian Schaefer, Technical Services Manager
Cooking instructions are considered an essential part of any new product development or existing product modification. Proper cooking instructions play a pivotal role in ensuring that a product meets food safety standards and maintains proper appearance, flavor, aroma & texture. There are three areas to consider when designing an effective cooking validation:
- Combination of time vs. temperature to meet food safety standards
- Method of temperature evaluation
- Selection of cooking equipment to be used
Combinations of Hold Time vs. Hold Temperature
Cooking validation relies on a combination of hold time and hold temperature to ensure a product meets food safety standards for human consumption. Hold times are defined as the amount of time that a product remains at the final temperature (hold temperature) after it has been removed from a heat source.2 Typically, when determining time vs. temperature combinations, an internal temperature of 165.2°F for 12 seconds is targeted to achieve a two log reduction of L. monocytogenes1 for ready-to-eat products and 165.2°F for 35 seconds in not ready-to-eat products. Since time vs. temperature combinations can vary, it is important to consider how the product will be consumed prior to determining the proper combination of hold temperature vs. hold time. For example, a single serve product with a hold temperature 158°F would require a 40 second hold time, however, shorter hold time could be more appropriate if the product may be consumed immediately after cooking. This scenario would require a higher hold temperature be achieved. Table 1 shows the hold times required to achieve 2, 4 or 6 log reduction depending on the hold temperature (calculated from ECFF, 20061).
Method of Temperature Evaluation
Oftentimes, a product may not be uniformly heated during the cooking process; resulting in cold spots and undercooked areas in the product. Due to this, it is essential to identify cold spots and undercooked areas that may not reach the required temperature so that accurate cooking instructions can be developed. This can be done using anywhere from 1-10 probes simultaneously to measure the internal temperature of a product over at least a 2 minute interval. This temperature data is used to generate accurate post-cooking heating & cooling curves and ensures that proper cooking instructions are created.
Selection of Cooking Equipment
It is important to note that not all ovens or microwaves heat equally. When selecting a microwave, the label wattage does not always match the operating wattage of the unit. Verifying the operating wattage of the unit is essential to understanding the impact on the cooked product. For ovens, the power type (electric vs gas), size of the cabinet, trimming patterns while heating, and design (built-in vs. freestanding) all have an impact on cooking and can affect cook times. To account for these variations, multiple different types of equipment are selected and multiple replicates performed to ensure the cooking validation is robust.
If the desired cooking instructions are not sufficient, modifications can be attempted to achieve the required temperatures. Potential cooking instruction modifications could include:
- Instructions to stir product after cooking
- Instructions to rest product after cooking
- Additional cook time
- Cooking at different power/temperature levels
- Cooking the product covered or uncovered
- Flipping the product during cooking
Do you know how accurate your cooking instructions are for your products? Or have you recently changed one of your products and need to validate if your instructions are still correct? We can help validate that your cooking instructions ensure your products meet food safety standards. Please reach out to our Customer Service team at firstname.lastname@example.org for more information.