Tag Archives: analysis

Granulated sugar with dark foreign particles

Food Investigations: Microanalytical Methods Find Foreign Matter in Granular Food Products

By Mary Stellmack
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Granulated sugar with dark foreign particles

The upcoming implementation of FSMA will likely result in increased scrutiny of contaminants in food products. If the foreign matter can be identified, steps can be taken to eliminate the source of contamination and avoid future losses of product. Small foreign particles are sometimes observed in drums of bulk granular or powdered raw materials. While these foreign particles may be seen as dark specks in the product, they are often too small for standard QA/QC methods of analysis. Microanalytical techniques, however, can be used to isolate and identify the specks. This article describes a case study of dark particles in a granulated sugar sample.

Microscope Exam

Ideally, when conducting contaminant analysis, all sample manipulations take place in a cleanroom to eliminate the chance for contamination by extraneous environmental debris. This is especially important when working with small contaminant particles, which may consist of environmental debris such as metal particles, fibers and other types of dirt. If the unknown particles are identified as common environmental debris, the analyst must be certain that he or she did not introduce any debris while handling the unknown sample.

Granulated sugar with dark foreign particles
Figure 1. Granulated sugar with dark foreign particles, 13X (Click to enlarge)

The first step in the identification process involves examination of the sample under a stereomicroscope. Figure 1 is a photomicrograph of dark brown particles, less than 1 mm in size, in the sugar sample. Particles of this size must be isolated from the bulk product prior to analysis in order to correctly identify them.

Since all of the dark particles are visually similar, only a few representative particles need to be isolated. The contaminants can be isolated by removing a small glob of tacky adhesive (50 µm or smaller) from a piece of tape with the pointed tip of a fine tungsten needle. The adhesive-coated needle tip is gently touched to the surface of one of the dark particles, causing the particle to adhere to the needle, and the particle is transferred to a glass slide or other substrate for further examination.

Isolated dark foreign particles
Figure 2. Isolated dark foreign particles, 63X. (Click to enlarge)

Figure 2 is a photomicrograph of three dark particles, isolated from the sugar granulation. The dark brown particles have a smooth, shiny appearance with conchoidal (shell-shaped) fracture surfaces, and are visually consistent with glass. However, when probed with the tungsten needle, the particles are found to be brittle and fragile, and this texture is not consistent with glass. Therefore, chemical analysis is needed to identify the brown particles.

Micro-FTIR Analysis to Identify Organic Components

Most organic compounds (and some inorganic materials) can be identified by Fourier transform infrared (FTIR) spectroscopy. For the analysis of small particles, a microscope is coupled with a standard FTIR system; this method of analysis is known as micro-FTIR analysis. The micro-FTIR system passes a beam of infrared radiation through the sample and records the different frequencies at which the sample absorbs the light, producing a unique infrared spectrum, which is a chemical fingerprint of the material. By comparing the spectrum of the sample with spectra of known compounds from a reference library through an automated computer search, the sample can often be identified.

In order for the FTIR analysis to work, the sample must be transparent, or thin enough to transmit light. In the case of the particles from this case study, this is achieved by applying pressure to a ~50 µm portion of the sample until it forms a thin transparent film. This film is placed on a salt crystal for micro-FTIR analysis.

An FTIR spectrum of crystalline sugar is shown in Figure 3, and a spectrum of a brown particle is shown in Figure 4. The spectrum of the brown particle has some similarities to sugar, but there are fewer peaks, and the remaining peaks are rounded, consistent with a loss of crystallinity. The loss of crystallinity, coupled with the brown color of the particles, suggests charred sugar.

FTIR spectrum of granulated sugar
Figure 3. FTIR spectrum of granulated sugar. (Click to enlarge)

Figure 4. FTIR spectrum of a dark foreign particle, microanalysis
Figure 4. FTIR spectrum of a dark foreign particle. (Click to enlarge)

SEM/EDS to Identify Inorganic Compounds

The FTIR method does not provide complete information about the presence or absence of inorganic materials in the contaminant. To complete the analysis of the brown particles, scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectrometer (EDS) detector is needed. Using the SEM/EDS method, two types of information are obtained: SEM provides images of the sample, and the EDS identifies the elements that are present.

SEM/EDS analysis of a dark foreign particle
Figure 5. SEM/EDS analysis of a dark foreign particle

A brown particle was mounted on a beryllium stub with a small amount of adhesive, and submitted for SEM/EDS analysis. Figure 5 includes an SEM image of the particle, and a table of EDS data. The SEM image provides some information about the composition of the particle. This image was acquired using backscattered electron mode, in which heavier elements appear lighter in color. The image displays light colored specks scattered across the surface of the particle, indicating that more than one type of material is present. The light-colored circle on the SEM image shows the area that was included in the EDS analysis (the entire particle was analyzed). Looking at the column in the table for weight percent (Wt%), the particle consists primarily of carbon and oxygen, with small amounts of chlorine and iron. Carbon and oxygen are chemical constituents of sugar, but chlorine and iron are not.

SEM/EDS analysis of specks on a dark foreign particle
Figure 6. SEM/EDS analysis of specks on a dark foreign particle

The EDS system can also be used to focus on individual small areas on the particle. Figure 6 includes EDS data from five specific light-colored specks on the surface of the brown particle. The specks contain major amounts of iron with small amounts of chlorine, and sometimes chromium and silicon, plus contributions from carbon and oxygen from the surrounding sugar matrix. The composition of the specks indicates steel corrosion, likely from low alloy steel. The presence of chlorine suggests that a chlorinated substance was the initiator for the corrosion process.

In some cases, steel corrosion can be the sole cause of brown or dark discoloration of small particles. In the case of this brown particle, the SEM image shows that the iron-rich particles are not evenly distributed throughout the particle, but are only scattered on the surface. Charring is the most likely cause of the overall brown color of the particle.


When examined under the microscope, the dark particles in the sugar sample had the visual appearance of glass. However, chemical microanalysis of the particles revealed that they were not glass at all, highlighting the importance of microanalytical methods in determining the identity of the foreign matter. The brown particles were ultimately identified as charred sugar particles with scattered specks of steel corrosion (likely from low alloy steel) on the surface. This information can be used to narrow down the search for possible sources of the brown particles in the bulk sugar sample. As part of a root cause investigation, samples of dark particles from various locations in the manufacturing and packaging processes can be studied by the same techniques to look for a match.

More information about FTIR analysis is available in the webinar, Preparation of Polymer Samples for Microspectroscopy

Sample6 executives, Tim Curran, Jim Godsey and Mike Koeris

Food Safety Testing Must Live Up to Higher Expectations

By Maria Fontanazza
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Sample6 executives, Tim Curran, Jim Godsey and Mike Koeris

From sanitation and processing to testing and analysis to transportation and imports, government requirements of companies in the food industry are changing. Many companies are already prepared for the transformation that FSMA will bring. Within food testing and analysis, expectations will be higher than ever. Companies should be able to more accurately and rapidly identify contamination in order to take immediate action. What are some of the biggest concerns in testing and analysis? What changes can we expect? In a roundtable discussion with Sample6 executives, Michael Koeris, Ph.D., founder and vice president of operations, Tim Curran, CEO, and Jim Godsey, vice president of research & development, share their perspective on the hurdles that industry is facing and how innovative technology plays an important role in the future of food safety.

Key trends:

  • Focus in testing shifts from not just testing and recording data, but also analyzing and communicating results. Having data analysis and reporting skills will be a critical function for the next generation of food safety professionals.
  • Be proactive, not reactive. If you’re finding problems at the finished product level, it’s too late.
  • The need for stronger partnerships between industry and government, especially relating to providing industry with the tools to effectively gather and analyze data in a timely manner.

Food Safety Tech: What are the current industry challenges, especially related to advances in pathogen detection technology?

Tim Curran, CEO of Sample6, pathogen detection
Tim Curran, CEO of Sample6

Tim Curran: When I look at food companies and food safety managers, [their jobs] have become harder to do well, instead of easier. The environment in which they’re working is more challenging, and the pressures are increasing. There’s more regulatory scrutiny, whether we talk about FSMA or the regulatory environment [in general], and there are more testing and inspection [expectations].

Second, the nature of the foods that we need make for the U.S. population (and I think it is a trend around the world): Ready-to-eat products. We’re producing products that are more convenient for families where they won’t necessarily have a cook step down the road. The kinds of foods in demand have a higher risk profile.

Third is the globalization of food supplies. Raw materials are coming in from all different directions, and there is an increasing number of shipping points. That creates more pressure, and from a food safety perspective, that is a bad thing.

“It is okay to find positives for Listeria or Salmonella in the appropriate zones that are far away from food contact surfaces. It is inconceivable to have a plant that has no actual bacterial organisms living there.” -Michael KoerisFinally, there’s social media. There’s a lot of scrutiny from the public. Information around any kind of fear or recall is rapidly disseminated.

These factors add up to higher pressure, a higher bar, and a harder job to accomplish—and the tools and methods available to keep the plant safe and food safe are not keeping pace.

Although I think food plants want to test more at the point of contamination, it’s just not possible. Unless they have a sophisticated lab, most food companies ship out samples because enrichment is required. As a result, they’re getting feedback on the safety of their plant and food in two, three, or four days, depending on where they fall as a priority to that outside lab.

Jim Godsey: With FSMA, testing is decentralizing from the larger lab, which is typically staffed with experienced personnel, to the facility where those personnel don’t exist. Having a test with a workflow that can be easily accommodated by someone with a high school education is absolutely critical for the field.

Michael Koeris, Ph.D., founder and vice president of operations, Sample6, pathogen detection
Michael Koeris, Ph.D., founder and vice president of operations

Michael Koeris: Visibility of data is generally extremely poor, because many people touch individual data points or pockets of data. The hand-off between the different groups is usually shaky, and the timeliness of delivering data to the operators has been a huge issue. This has been an opportunity for us: Our control offering is an operating system for environmental control. It’s an open system, so it accepts both our data and other people’s data, enabling visibility across an entire corporate infrastructure. Plant managers and other [users] of these systems can generate timely reports so they can see what is happening on a daily basis.

FST: In considering professional development, what skills are necessary to ensure that employees will be well equipped to address the issues discussed here?

Godsey: The role of the food safety manager becomes a much more critical and challenging role. To support that, they need better tools; they need to know with a high degree of confidence that their facility has been tested, that the testing was done at the proper times and intervals, and that the data has been analyzed in a timely manner. It’s not just assay/analysis [or] reporting results anymore; it’s the holistic review of those results and translating that [information] into whether or not the plant is safe at that point in time.

Koeris: The persona of the food safety manager is changing. They need to see themselves as the brand protection manager. If you have food safety issues, your brand is at risk. We need to empower the food safety manager at the local level to act, remediate and change processes.

Jim Godsey, vice president of research & development, Sample6, pathogen detection
Jim Godsey, vice president of research & development

There also has to be fundamental change in the industry in how results are viewed. Not all tests are created equal. It is okay to find positives for Listeria or Salmonella in the appropriate zones that are far away from food contact surfaces. It is inconceivable to have a plant that has no actual bacterial organisms living there. This is not a pharmaceutical production facility. Setting the wrong goals at the corporate level of zero positives disincentivizes operators to not look hard enough. You have to actually understand the plant and then make sure that you’re safe with regards to your control plan.

FST: How do you expect the final FSMA rules and implementation process will impact industry?

Koeris: Most of the larger food players are already doing what FSMA mandates or will mandate. The medium and smaller processors will have to adapt and change. They have to implement better standards and more standards, more surveillance, and implement more rigorous processes. The [key] is to help them do this on a tight budget.

FSMA has increased awareness of food safety across the supply chain. It is still focused on the processors, but we know it doesn’t stop there; it doesn’t stop at the distributor or the retailer. Food safety has to be throughout that supply chain.

Having an understanding and awareness of all of the challenges that exist downstream—that will [lead to] the real innovation and increase in foods safety.

John A. Wadie, U.S. Marketing Development Manager, 3M

Interview: 30 Years of Petrifilm Technology

By Sangita Viswanathan
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John A. Wadie, U.S. Marketing Development Manager, 3M

3M Food Safety celebrated a milestone this past summer – the 30th anniversary of its PetrifilmTM Plates – currently the worldwide standard for fast, simple, easy-to-interpret indicator testing.

First introduced in 1984, the 3M Petrifilm Plate technology has long been the industry standard for efficient and reliable colony interpretation and enumeration for the F&B industry. In a chat with Food Safety Tech, John A. Wadie, U.S. Marketing Development Manager for 3M Food Safety Department, talked about the adoption of Petrifilm continuing to grow worldwide, which spoke to the product’s value and utility to the industry. We present below excerpts from a Q&A.

FST: How has the food safety environment changed in the last 30 years?

Wadie: The food industry has become increasingly global, with great awareness among consumers about food safety issues. The combination of these trends, combined with constant information dissemination on a variety of food safety issues, has placed enormous pressure on food companies to test more, do it faster and do it more efficiently. From a regulatory stand point also, there is much more pressure on food companies to proactively maintain and manage stringent food safety procedures, and testing plays a big role in managing this. The biggest change has occurred with the speed of testing. Alongside even faster testing, is the demand for accurate and consistent testing and results.  

FST: What attributes of Petrifilm Plates have made it so popular over the last 30 years?

Wadie: With more than 2 billion units sold and counting, 3M Petrifilm Plates are the world’s leading food indicator testing technology. They are currently in used by all kinds of food processors, universities, governments and third-party contract labs in no fewer than 65 countries.

3M-Petrifilm-July-2014The standout feature of the product, and probably the primary reason for its longevity, is its simplicity, due to the fact there is no need for customers to prepare, purchase or store agar dishes. The technology has also received numerous country-specific, as well as global, validations from multiple, rigorous sources. With Petrifilm Plates, you also ensure the consistency and accuracy of test results from technician to technician, and between plant locations, and these are very important attributes in the current multi-location setting of food companies.

FST: Against the backdrop of FSMA, how is food safety testing set to change in the near future?

Wadie: With new regulations, there’s even greater focus on food safety testing, and getting fast, consistent and accurate results. The regulations, and the standards benchmarked under GFSI, are also laying emphasis on how the testing is done, where it’s done, and who is doing it.

The next 30 years will continue to bring faster and more accurate methods of testing as well as improvements to the preparation process. With greater innovation and rapid detection technologies, it may soon be possible to do inline testing – to identify pathogens and bacteria within production lines as opposed to testing being a separate step.