Microbiology Quality Control in Food and Beverage

Food contaminated by microorganisms (bacteria and yeasts), viruses, and protozoa can cause severe disease in humans. There are two categories of foodborne diseases.

  • First, food poisoning is caused by the presence of microbial toxins in food products, e.g. by Staphylococcus aureusClostridium perfringens (both produce enterotoxins which elicit enteric disease such as diarrhea), and Clostridium botulinum(botulism is the most severe type of food poisoning).
  • Second, the growth of microorganisms in the body after eating contaminated food, e.g. by Salmonella spp. (salmonellosis) and Campylobacter jejuni (high fever, abdominal cramps). Many human pathogens are transmitted by fecal contaminated water, the most important being Salmonella typhi (typhoid fever) and Vibrio cholerae (cholera).

Microbiological test procedures for the examination of foods and beverages have been standardized and regulated, but nearly every country has its own regulations. Most of the culture media, additives, dyes, and indicators, which Sigma-Aldrich offers, conform to norms like ISO. Product lines include:

  • Culture media and base ingredients
  • Chromogenic media for differentiation of microbes based on colony color
  • Test kits (biochemical, immunological, and molecular biological methods) for pathogen detection, identification, and confirmation
  • Vitroid certified reference microorganisms to test the performance of microbiological assays

Culture media and base ingredients are conveniently organized by food & beverage application for ease of locating the proper materials.

For simple and fast detection of bacteria, use media with a chromogenic substrate such as Salmon-GAL, X-Gal, and X-glucuronide. Certain enzymes, produced by some bacteria, cleave these substrates, resulting in the different coloration of specific bacteria colonies. This allows to clearly see the presence of the targeted microorganism, observed as a clearly visible color change. Most chromogenic media is intended for detection of pathogenic bacteria, including our media for Clostridum perfringens, the first of its kind.

Sigma-Aldrich offer a wide selection of test and reagents for pathogen detection, identification, and confirmation.

Test for Classic Biochemical Methods

Classical reagents, kit systems or convenient discs and strips can be used in the identification and confirmation of microorganisms. Based on rapid screening methods like the detection of enzymes with chromogenic substrates, indicators, or on complex building reactions, they are faster and easy to use. Also, the sensitivity to certain inhibitory substances can be used to identify organisms.

Test Kits for Innovative Molecular Biological Methods

HybriScan rapid test kits are based on an rRNA sandwich hybridization system which is less expensive and more robust than PCR methods. They are also more accurate (only detects living cells), quicker (time savings of up to 10 days over cultivation-based assays), and can be performed with standard laboratory equipment. These kits can be used for the identification and quantification of spoilage and pathogenic microorganisms in foods and beverages. They are ideal for the comprehensive and reliable routine control of raw materials and concentrates in all production steps, up to the quality check of finished goods.

Test Kits for Innovative Immunological Methods

The easy-to-use Staphylo Monotec Test Kit Plus is a rapid agglutination test for differentiation between Staphylococcus aureus and other Staphylococcus. With this kit, three characteristic properties (coagulase, protein A, and capsular serotype 5 polysaccharide) of S. aureus can be detected in one step with high reliability. This results in increased sensitivity and specificity in detecting methicillin resistant Staphyloccocus aureus.

Through our Vitroids™ and LENTICULE® discs range, Sigma-Aldrich is the first company to produce certified reference test strains under double accreditation. They are certified according to ISO 17025, produced under ISO Guide 34, and meet UKAS guidelines. These products contain a precisely defined and certified cfu level in a dried state on small discs.

Sigma-Aldrich also offers certified reference DNA.

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