Tag Archives: foreign materials

Manuel Orozco, AIB International
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Detecting Foreign Material Will Protect Your Customers and Brand

By Manuel Orozco
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Manuel Orozco, AIB International

During the production process, physical hazards can contaminate food products, making them unfit for human consumption. According to the USDA’s Food Safety and Inspection Service (FSIS), the leading cause of food recalls is foreign material contamination. This includes 20 of the top 50, and three of the top five, largest food recalls issued in 2019.

As methods for detecting foreign materials in food have improved over time, you might think that associated recalls should be declining. To the contrary, USDA FSIS and FDA recalls due to foreign material seem to be increasing. During the entire calendar year of 2018, 28 of the 382 food recalls (7.3%) in the USDA’s recall case archive were for foreign material contamination. Through 2019, this figure increased to approximately 50 of the 337 food recalls (14.8%). Each of these recalls may have had a significant negative impact on those brands and their customers, which makes foreign material detection a crucial component of any food safety system.

The FDA notes, “hard or sharp foreign materials found in food may cause traumatic injury, including laceration and perforation of tissues of the mouth, tongue, throat, stomach and intestine, as well as damage to the teeth and gums”. Metal, plastic and glass are by far the most common types of foreign materials. There are many ways foreign materials can be introduced into a product, including raw materials, employee error, maintenance and cleaning procedures, and equipment malfunction or breakage during the manufacturing and packaging processes.

The increasing use of automation and machinery to perform tasks that were once done by hand are likely driving increases in foreign matter contamination. In addition, improved manufacturer capabilities to detect particles in food could be triggering these recalls, as most of the recalls have been voluntary by the manufacturer.

To prevent foreign material recalls, it is key to first prevent foreign materials in food production facilities. A proper food safety/ HACCP plan should be introduced to prevent these contaminants from ending up in the finished food product through prevention, detection and investigation.
Food manufacturers also have a variety of options when it comes to the detection of foreign objects from entering food on production lines. In addition to metal detectors, x-ray systems, optical sorting and camera-based systems, novel methods such as infrared multi-wavelength imaging and nuclear magnetic resonance are in development to resolve the problem of detection of similar foreign materials in a complex background. Such systems are commonly identified as CCPs (Critical Control Points)/preventive controls within our food safety plans.

But what factors should you focus on when deciding between different inspection systems? Product type, flow characteristics, particle size, density and blended components are important factors in foreign material detection. Typically, food manufacturers use metal and/or x-ray inspection for foreign material detection in food production as their CCP/preventive control. While both technologies are commonly used, there are reasons why x-ray inspection is becoming more popular. Foreign objects can vary in size and material, so a detection method like an x-ray that is based on density often provides the best performance.

Regardless of which detection system you choose, keep in mind that FSMA gives FDA the power to scientifically evaluate food safety programs and preventive controls implemented in a food production facility, so validation and verification are crucial elements of any detection system.

It is also important to remember that a key element of any validation system is the equipment validation process. This process ensures that your equipment operates properly and is appropriate for its intended use. This process consists of three steps: Installation qualification, operational qualification and performance qualification.

Installation qualification is the first step of the equipment validation process, designed to ensure that the instrument is properly installed, in a suitable environment free from interference. This process takes into consideration the necessary electrical requirements such as voltage and frequency ratings, as well as other factors related with the environment, such as temperature and humidity. These requirements are generally established by the manufacturer and can be found within the installation manual.

The second step is operational qualification. This ensures that the equipment will operate according to its technical specification. In order to achieve this, the general functions of the equipment must be tested within the specified range limits. Therefore, this step focuses on the overall functionality of the instrument.

The third and last step is the performance qualification, which is focused on providing documented evidence through specific tests that the instrument will performs according to the routine specifications. These requirements could be established by internal and industry standards.

Following these three steps will allow you to provide documented evidence that the equipment will perform adequately within the work environment and for the intended process. After completion of the equipment validation process, monitoring and verification procedures must be established to guarantee the correct operation of the instrument, as well procedures to address deviations and recordkeeping. This will help you effectively control the hazards identified within our operation.

There can be massive consequences if products contaminated with foreign material are purchased and consumed by the public. That’s why the development and implementation of a strong food safety/ HACCP plan, coupled with the selection and validation of your detection equipment, are so important. These steps are each key elements in protecting your customers and your brand.


Tyson Recall Affects 30,000+ Pounds of Frozen Chicken Patties

By Food Safety Tech Staff
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Yesterday Tyson Foods, Inc. announced a recall of its Weaver brand frozen chicken patties over concern that they could be contaminated with foreign materials. The Class I recall affects 39,078 pounds of frozen, fully cooked product that were produced on January 31 of this year and shipped to retailers nationwide. The recall was initiated after Tyson informed FSIS of consumer complaints.

Particles on filter

Microanalytical Methods Identify Foreign Materials for FSMA Compliance

By Debra L. Joslin, Ph.D
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Particles on filter

Implementation of FSMA will result in greater scrutiny of foreign material in food products at every stage of production, as well an entirely new pressure to locate and eliminate the source of contamination from the supply and production chain. Identifying foreign materials found in food products is the first step in determining their source, and therefore in determining how to prevent a given foreign material from being introduced into the product. For identification of small particles ranging from 1–1000 µm, microanalytical techniques are essential.

Examining and Isolating Foreign Material

Before the foreign material is prepared for analysis, the material is examined under a stereomicroscope. Ideally, isolation of the foreign particles from the host matrix and preparation of the foreign particles for microanalysis is performed in a cleanroom, which mitigates the introduction of environmental contamination not related to the initial contamination problem.

Particles on filter
Figure 1. Particles filtered from a liquid product.

Under the stereoscope, the foreign material is isolated from the product matrix using a tungsten needle probe. It is photographed and the physical characteristics of the material (color, elasticity, magnetic properties, etc.) are observed and documented. Figure 1 shows particles filtered from a liquid product. In this case, the particles are approximately 100 μm and smaller. Most of the particles appear black to dark brown/orange in color. Some are brittle, while others are not. All are magnet responsive.

Only a few particles must be picked and prepared for analysis in this case because the particles are roughly similar. The coloration of the particles, along with their mechanical properties (magnetic, brittle, hard) indicate that the material is likely inorganic; scanning electron microscopy with energy dispersive X-ray microspectrometry (SEM-EDS) could be used to determine the elemental makeup of the material. The coloration and mechanical properties imply the source of the particles could be production machinery.

Figure 2. Corrosion
Figure 2 (click to enlarge)

Identifying Inorganic Compounds with SEM-EDS

In a scanning electron microscope, a beam of electrons is scanned over the particle producing several signals, some of which are used for imaging, and some that are used for elemental analysis. For this discussion, the signals of interest for elemental analysis are X-rays. The energies of the X-rays are characteristic of the elements found in the sample. By counting these X-rays and arranging them according to their energies, a spectrum is produced, and elements in the sample can be identified and quantified.

Corrosion inclusions
Figure 3 (click to enlarge)

Figures 2 and 3 are SEM-EDS data from one of the brittle particles from the filter. The particle is steel corrosion (iron, chromium, and nickel), possibly with brass corrosion (copper and zinc) and some silicate material (elevated silicon and aluminum). Residues of corrosive agents (chlorine and sulfur) are present. The inclusions analyzed are 300 series stainless steel (see Figure 2). SEM-EDS data from one of the harder dark particles is shown in Figure 4. This particle is oxidized 300 series stainless steel, likely Type 316. 300 series stainless steels are not generally magnetic, but magnetism can be induced during wear processes.

Harder dark particles
Figure 4. SEM-EDS data from harder dark particles. (click to enlarge)

Stainless steels, particularly Type 304 and Type 316 are common in food manufacturing environments. Pinpointing the source of these materials as contaminants can be frustrating due to the number of pieces of equipment made from these alloys. However, other metals are less common, such as Waukesha 88, a bismuth containing nickel-based alloy that is used in pump rotors and other moving parts because of its wear properties. Another less-common alloy is Type 321 stainless steel, a titanium stabilized stainless steel that is used in high temperature equipment where corrosion resistance is needed. Materials such as these are more easily traceable to their source, and therefore more easily repaired and thus eliminated as a source of foreign particles.

Glass particle
Figure 5. Glass particle. (click to enlarge)

Other inorganic materials, such as glass, are also amenable to identification by SEM/EDS. SEM-EDS data from a glass particle is shown in Figure 5. Often, the glass can be identified as soda-lime glass or borosilicate glass. Soda-lime glass is commonly used for glass containers and bakeware; it is a mixture of oxides, mostly silicon dioxide, sodium oxide, and calcium oxide with smaller amounts of other oxide compounds. Borosilicate glass, commonly used in heat-resistant labware, contains silicon dioxide with a few weight percent boron trioxide, along with other oxide compounds; its composition results in a low coefficient of thermal expansion, and it is used in applications where its chemical and heat resistance are necessary. Identifying the glass type is helpful in determining the source of glass particles.

Identifying Organic Compounds using Fourier Transform Infrared Micro Spectroscopy (Micro-FTIR) Analysis

Reference spectrum for Viton
Figure 6. Reference spectrum for Viton. (click to enlarge)

The SEM-EDS method cannot uniquely identify organic compounds, as it provides only elemental information—an EDS spectrum of organic material shows major carbon, and if it is degraded, oxygen. Protein will contain nitrogen as well.

Cellulose IR spectrum
Figure 7. Cellulose IR spectrum. (click to enlarge)

FTIR analysis can identify most organic and a few inorganic materials. For small particles, micro-FTIR (an FTIR system with a microscope coupled to it) is used. Micro-FTIR analysis requires that the sample be thin enough to transmit light, since the system passes a beam of infrared radiation through the sample and records the frequencies at which the sample absorbs infrared radiation. The spectrum from a given material is unique, and even mixtures of materials can often be identified by comparison to known spectra from a reference library using an automated computer search.

Cardboard IR spectrum
Figure 8. Cardboard IR spectrum. (click to enlarge)

In this way, organic materials such as Viton O-rings can be identified (Figure 6 is a reference spectrum for Viton). Other organic material may be present in the product, such as cellulose (see Figure 7) or cardboard (see Figure 8). While these materials are not dangerous as small particles, they are not desirable in food products. When these kinds of things are found, tracing them to their source may be simple (as in the case of the O-ring material) or hard (cellulose can come from paper or cotton clothing, for example).

If the organic material found has inorganic fillers like titanium dioxide or silicon dioxide, then SEM-EDS can be used in concert with the micro-FTIR to refine the material description and simplify the process of identifying the source of the foreign material.

When used in tandem, SEM-EDS to identify inorganic materials and micro-FTIR to identify organic materials can be powerful tools for determining the origin of foreign particles. These microanalysis methods are essential tools for identifying and tracing the source of contaminant particles in food.