Microbial Contamination and Hygiene Indicator Bacteria You Need to Know
Food safety and quality are essential for maintaining human health. Food contains various nutrients that support the growth of microorganisms, including those that cause food-borne diseases.
Therefore, strict monitoring of pathogenic microorganisms in food products is crucial. A group of Gram-negative bacteria frequently found in contaminated food is the Enterobacteriaceae family, such as Salmonella, Escherichia coli, and Klebsiella.
This group of bacteria is used as an indicator of microbiological contamination in food products. Thus, testing the number of Enterobacteriaceae in food products becomes very important as part of hygiene inspection.
The enumeration method for Enterobacteriaceae in food products is based on ISO 21528-2:2017 concerning food production and handling. To validate or verify the accuracy and reliability of this method, ISO 16140-3:2021 is used as the guideline for validation and verification of microbiological methods in food.
This method is based on conventional techniques; therefore, the main characteristics of a standard must be fulfilled.
The Importance of Microbial Contamination Limits in Food
Microbial contamination limits are standards that define the number and types of microorganisms that are still allowed in food to ensure it is safe for consumption. Each country has its own regulations regarding microbial limits.
In Indonesia, microbial contamination limits are regulated by BPOM and SNI to protect consumers. These limits are crucial because they protect consumers from various foodborne diseases such as diarrhea, food poisoning, typhoid fever, cholera, and Salmonella infections caused by foods contaminated with pathogenic microorganisms.
With contamination limits in place, the risk of these diseases can be significantly reduced. Microbial limits also serve to assess the cleanliness of production processes.
This evaluation is determined based on the number of coliform bacteria (a group naturally found in the environment and the digestive tract). A high number of coliforms indicates poor hygiene during production—whether from water, equipment, or workers.
Microbial contamination testing also ensures product quality, as high microbial counts can cause food spoilage, changes in taste, color, and aroma, nutritional loss, and the appearance of slime or gas. Compliance with regulations and trade standards also requires microbial contamination testing.
BPOM regulates several key microbiological parameters to determine food safety, including:
- Salmonella: must not be detected in a specified amount of sample (for all types of processed food), as it is a serious pathogen that causes food poisoning. Products testing positive for Salmonella are automatically unsafe for consumption.
- Enterobacteriaceae: this group is not always pathogenic, so a safe limit is set per gram of sample. The typical limit is ≤ 100 CFU/g for processed food products.
- Yeasts and molds: these microorganisms serve as indicators of storage quality and hygiene. The safe limit is usually ≤ 1,000 CFU/g for processed foods. High counts pose risks of spoilage, off-flavors, or mycotoxin production by molds.
Enterobacteriaceae and Coliform Bacteria
Enterobacteriaceae is a large family of Gram-negative bacteria that includes many species. These bacteria are used as indicators of processing and sanitation—not specifically fecal contamination.
This group includes pathogenic bacteria (Salmonella, Shigella, Yersinia, etc.) as well as non-pathogenic species. Therefore, this group is broader than coliforms. Coliforms are a subset of Enterobacteriaceae that can ferment lactose, producing acid and gas, and grow optimally at 35–37°C.
Coliform bacteria are commonly used as indicators of water and environmental hygiene, and sometimes as indicators of fecal contamination. Examples include E. coli, Enterobacter, Klebsiella, and Citrobacter.
Detection of both coliforms and Enterobacteriaceae is typically carried out using the Total Plate Count (TPC) method on general media such as VRBGA and MacConkey agar. These media allow colonies with characteristic pigments and morphologies to grow.
By understanding the role of each bacteria group, food industry operators can implement more targeted controls to ensure products are safe, hygienic, and compliant with BPOM regulations. Good microbiological monitoring not only prevents foodborne diseases but also improves product quality and consumer trust.
Given the complexity of microbiological contamination risks in food and the strict BPOM and SNI regulations, control measures cannot rely on production processes alone. Accurate and reliable microbiological testing is essential to ensure that products are truly safe, hygienic, and compliant with established microbial limits.
Without valid laboratory test data, food businesses may struggle to demonstrate product safety and maintain consumer trust. To support this need, IML Testing and Research provides microbiological testing services for food products, including analysis of Enterobacteriaceae, coliforms, Salmonella, as well as molds and yeasts in accordance with applicable standard methods.
Through comprehensive, accurate, and reliable testing, these services help ensure production hygiene, regulatory compliance, and product quality before reaching consumers.
Author: Safira
Editor: Sabilla Reza
References:
Badan Pengawas Obat dan Makanan Republik Indonesia. (2019). Peraturan Badan Pengawas Obat dan Makanan Nomor 13 Tahun 2019 tentang Batas Maksimal Cemaran Mikroba dalam Pangan Olahan.
Nagur, K., Surati, S., Sitorus, A. A. M., Cahyaningsih, E., Putri, F., & Wilasti, Y. (2023). Implementation of ISO 16140-3:2021 for enumeration of Enterobacteriaceae in food products. ERUDITIO, 4(1), 88–96.
U.S. Food and Drug Administration. (2020). Bacteriological Analytical Manual (BAM), Chapter 4: Enumeration of Escherichia coli and the coliform bacteria. FDA.
