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The Importance of Compressed Air and Gas Testing to Beverage Quality and Safetycompressed air testing gas testing beverage quality and safety
Contamination of compressed air and gases used in beverage manufacturing can lead to beverage recalls, reduced product shelf life, changes in taste and appearance of products, and overall lost profits and a tarnished company reputation. For example, in 2001, one of the largest food and beverage companies in North America recalled over 140,000 cases of product due to contamination with a compressed air system lubricant (1).
Food-borne illnesses alone are estimated to cost the United States $93.2 billion annually, a hefty increase from the $77.7 billion estimated in 2012 (2). Beverage companies applying Hazard Analysis and Critical Control Point (HACCP) principles, included in the International Standards Organization (ISO) 22000 Food Management System (3), deem compressed air and gases as critical control points, vital to beverage safety [Table 1]. International food safety standards exist to hold beverage manufacturers accountable for the safety of their products.
[Table 1]- Examples of critical control points for compressed air and gases in beverage manufacturing (20,21,22,23,24).
Major global and national standards and organizations, including the ISO (4), the British Compressed Air Society (BCAS) (5), the British Retail Consortium (BRC) (6), the Safe Food Quality Institute (SQF) (7), the Global Food Safety Initiative (GFSI) (8), and the U.S. Food and Drug Administration (FDA) (9), mandate or suggest monitoring of compressed air and gases used in beverage manufacturing. While compressed air and gas testing has become a requirement for these major food safety standards and organizations, specifications for compressed air and gases are few and far between. ISO 8573 has laid the groundwork for developing limits [Table 2] for contaminants in compressed air and gases. This standard considers particles (non-viable and viable), water, and oil as the key contaminants to monitor (4). The procedures outlined by ISO 8573: 1-9 can be modified to address pure and mixed compressed gases as well as gas distribution systems.
BCAS goes further in setting compressed air and gas standards for the beverage industry. BCAS recommends ISO 8573 purity classes to follow for indirect contact, purity classes 2:4:2 (non-viable particles: water: oil), and direct contact, purity classes 2:2:1 (non-viable particles: water: oil), of products with compressed air and gases in beverage manufacturing processes (5).
Beverage companies may test compressed air and gases used in their manufacturing solely to meet various standard guidelines; however, compressed air and gas testing also provides insights and important metrics that can be used to benefit and improve the quality of their beverage products and safety schemes. Annual testing, while sufficient to meet most international food safety standards, may not be enough to establish compressed air and gas quality trends. Testing frequency is a topic rarely discussed, but essential to leveraging compressed air and gas testing to benefit beverage quality. Key factors of compressed air and gas, particles (non-viable and viable), water, oil, gas purity, and gaseous contaminants, will be discussed with regards to their relationship to beverage quality and safety. Compressed air and gas testing is a vital supplement to compressor purification systems for ensuring that the compressed air and gases used in beverage manufacturing conform to industry standards and pose minimal risk to beverage quality and safety.
[Table 2]- ISO 8573 purity class. Include microbial contaminants.
Particles (non-viable and viable):
ISO 8573-4 discusses methodology for determining particle content (4), both liquid and solid; examples of particle contaminants include metal shavings, glass, tapes, rubbers, insect parts, plant debris, oil, liquid water and microorganisms. Particles can be introduced into beverage products from the ambient air intake and/or as a byproduct of the pneumatic machinery and engine combustion of the compressed air system.
When viable particles, or microorganisms (bacteria, yeast and mold) are required to be reported, ISO 8573-7 can be employed. While specifications for microbial contamination of compressed air and gases do not exist in the current standard, they should always be a result of a risk assessment by the quality department of the sampling facility. Particle contamination in beverages can result in changes to the taste, color/appearance, and texture of the final product. Consumers won’t want to drink beverages containing unidentifiable particulates as this could suggest unhygienic business manufacturing practices and/or a tainted beverage product. Particle contamination, especially by viable particles, jeopardizes the safety of the beverage and can result in lost profits and sick and unhappy customers. Proper filtration, with size limits appropriate for the diameter of the particle desired, should be employed just at the point-of-use and after the outlet area of the storage tank prior to the distribution system in order to prevent particle contamination of beverage products.
Per ISO 8573-3, water is measured in terms of pressure dew point, or the humidity of the compressed air (4). Ambient air, containing moisture, introduces water to the compressed air or gas system (10). To dry the compressed air before use, a series of air dryers and filter systems should be employed. Compressors lacking drying systems may result in water condensate and ultimately lead to a misting of the final product, which can impact the balance and homogeneity of beverage ingredients (11). High moisture content in compressed air and gas is harmful to the compressor system and leads to the creation of corrosion and metal oxides, such as rust (10), non-viable particles under ISO 8573 (4). These newly produced contaminants, which will exit the compressor system and make their way into beverage products, can affect the taste and appearance of beverages. Perhaps the biggest danger with moist compressed air is the creation of an ideal environment for certain microbes to grow, such as mold (11, 12). Thus, contamination generates additional contamination, and one can see the significance of water contamination to microbial and non-viable particle contamination.
Oil contaminants behave similarly to water in that they can both condense and vaporize. However, due to the weight of oil, a pressure drop will occur, slowing the efficacy of the compressor system (13). Oil in various forms, including as liquid, aerosol, and vapor, is considered under ISO 8573-2 & 5 as a major contaminant to monitor in compressed air. Oil contamination can originate from ambient air and/or the compressor itself, especially when using compressors that require lubricants in the compression chamber (14, 15). Oil contamination can result in recalls and can ruin beverage products by giving them off-flavors and an altered appearance and consistency. In beer, oil can flatten the frothy head and ruin the experience of the consumer (16). Oil contamination may also increase risk for microbial contamination by providing nutrients needed for microbial growth (17). Food-grade lubricants may help reduce the risk of harmful oil contamination reaching final beverage products, but this may not always be financially feasible as food-grade lubricants can be more costly upfront (18), compared to traditional industrial oils. These food-grade lubricants are still regulated and only minimal contact with food and beverage products is permitted (19).
Gas Purity and Gaseous Contaminants:
Compressed pure gases and mixtures of gases are used in beverage manufacturing for bottling, aeration, fermentation, carbonation, nitrogenation, and preservation (20,21,22,23,24, 25). The gases typically used in these applications include nitrogen, carbon dioxide, argon, and sulfur dioxide. Proper gas purity, with minimal to no gaseous contaminants, is vital to maintaining control and consistency with beverage manufacturing processes and for ensuring the quality and safety of the final product. Gaseous contaminants are often present in both compressed air and gases, originating from ambient air and/or within the compressor, and ISO 8573-6 considers carbon monoxide, carbon dioxide, sulphur dioxide, hydrocarbons (C1 to C5), and oxides of nitrogen as gaseous contaminants to measure. However, gaseous contaminants are not considered major contaminants per ISO 8573 and no purity classes are specified, leaving the beverage manufacturer to decide which gaseous contaminants (if any) to measure and appropriate limits to set for the given application.
Sulfur dioxide is a regulated gaseous contaminant, often used in beverage manufacturing for preservation and antimicrobial purposes, with limits set by the FDA and European Union (25, 26, 27, 28). Oxygen is of major concern to beverage manufacturers due to its oxidative effects. Excess oxygen can result in the creation of off-flavors and the degradation of colors, flavors, and clarity of the beverage product (29, 30, 31). In the case of fermented beverages, such as beer and wine, oxygen is needed during fermentation as yeast require oxygen to grow and expand (30, 31). However, after fermentation has begun, oxygen, even in small quantities, can result in stale/off-flavors, a hazy and/or mis-colored product, and a reduced shelf-life stability (30,31). Carbon dioxide is one of the most well-known of gases used in beverages and imparts effervescence, a tangy taste, and aids in the prevention of spoilage (32). The International Society of Beverage Technologists Carbon Dioxide Guidelines set forth recommendations for ensuring the quality of carbon dioxide used in beverage manufacturing (33) [Table 3]; the suggested limits for gaseous contaminants listed may also be used as a guide for other compressed gases.
[Table 3] International Society of Beverage Technologists Carbon Dioxide Guidelines (32).
Beverage manufacturers should consider their processes and perform a risk assessment to determine which gaseous contaminants and limits to use.
One of the most commonly posed questions to third party testing laboratories relates to the number of times a point-of-use needs to be tested in a calendar year. Facilities adhering to the BCAS Guidelines test compressed air quality twice per year or per the manufacturer's recommendations. ISO 8573 standards do not mention testing frequency and act only to provide methodologies and references for testing and limits. This leaves the sampling facility with the task of determining how often testing should be conducted. Often facilities will utilize risk assessments and HACCP training programs to establish a monitoring schedule. When a monitoring plan is initiated, the first data point is commonly referred to as a baseline, or the initial state of contamination for the point-of-use of the compressed air or gas system. Monitoring these critical check points and critical limits should always require procedures (trend analysis) that detect loss of control at the monitored site in real-time and over an extended period (34). When real-time analysis is conducted of a high-risk point-of-use, action and alert levels can be designated to signal drift from historical performance measurements (35). The facility can then develop a strategy to respond to these trends in line with the desired outcome. Trend analysis works best when multiple data points are available throughout a year. Too many data points and the information is redundant, too few and the information is inadequate. When done well, trend analysis can even give facilities ideas about how to change preventive maintenance and cleaning schedules to move results in a more predictable fashion.
Compressed air and gases are a vital utility and additive for beverage facilities today. However, this utility is susceptible to various types of contamination which can affect the quality and safety of beverage products, ultimately hurting a beverage company’s bottom line. While it is the duty of beverage companies to orchestrate a fine-tuned monitoring plan that analyzes all possible contaminants that can harm consumers, it is also in the best interests of beverage companies to complete extensive testing to improve and protect the quality of the beverages they produce. Combining air and gas treatments, such as dryers and filters, with regular monitoring enables beverage companies to ensure the quality of the compressed air and gases used in manufacturing. Monitoring the status of contaminants in compressed air and gas is an important step towards maintaining brand integrity, customer favorability and beverage quality and safety. For more information on compressed air and gas testing, contact us at email@example.com.
By: Maria Sandoval and Robert Stein of Trace Analytics, LLC
Maria Sandoval has over 15 years of experience in Microbiology and Molecular Biology. Her field work includes analyzing extremophiles isolated from the depths of Lake Baikal in Russia to the 50km exclusion zone of Chernobyl. Additionally, she’s worked alongside the CDC with DSHS analyzing and diagnosing patient microflora. Her tenure with the Lawrence Berkeley National Laboratory, Department of State Health Services and the University of Texas MD Anderson Cancer Center has made her a leading expert in microbial testing. As Trace Analytics’ Microbiologist and Lab Director, she is responsible for microbial testing and procedural development.
Robert Stein is a U.S. appointed expert on the ISO 8573 Compressed Air Testing Technical Committee and holds a BS in Chemistry and Archaeology and an MS in Forensic Chemistry. Robert has gained experience in varied scientific roles, including forensic anthropology, trace chemistry, molecular and cell biology, and clinical toxicology. Experienced in analytical chemistry and microscopy, he currently serves as the Quality Manager at Trace Analytics.
Trace Analytics is an A2LA accredited laboratory specializing in compressed air and gas testing for food and beverage manufacturing facilities. Using ISO 8573 sampling and analytical methods, their laboratory tests for particles (0.5-5 microns), water, oil aerosol, oil vapor, and microbial contaminants found in compressed air. For over 29 years, they’ve upheld the highest industry standards of health and safety, delivering uncompromising quality worldwide in accordance with ISO, SQF, BRC, and FDA requirements. Visit www.AirCheckLab.com
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