A Survey of Coliforms and Staphylococcus aureus in Cheese Using Impedimetric and Plate Count Methods

Khayat, F. A.; Bruhn, John C.; Richardson, G. H.

doi:10.4315/0362-028x-51.1.53

Cited by 13 publications

(3 citation statements)

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“…Coliforms are widely found in many cheeses ( Khayat et al, 1988 ; Brooks et al, 2012 ). However, in contrast to the presence of these microbes in raw and pasteurized fluid milk, and even in some other cultured products (e.g., yogurt), the presence of coliforms in cheese may not necessarily be negative.…”

Section: Introductionmentioning

confidence: 99%

The Evolving Role of Coliforms As Indicators of Unhygienic Processing Conditions in Dairy Foods

et al. 2016

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Testing for coliforms has a long history in the dairy industry and has helped to identify raw milk and dairy products that may have been exposed to unsanitary conditions. Coliform standards are included in a number of regulatory documents (e.g., the U.S. Food and Drug Administration’s Grade “A” Pasteurized Milk Ordinance). As a consequence, detection above a threshold of members of this method-defined, but diverse, group of bacteria can result in a wide range of regulatory outcomes. Coliforms are defined as aerobic or facultatively anaerobic, Gram negative, non-sporeforming rods capable of fermenting lactose to produce gas and acid within 48 h at 32–35°C; 19 genera currently include at least some strains that represent coliforms. Most bacterial genera that comprise the coliform group (e.g., Escherichia, Klebsiella, and Serratia) are within the family Enterobacteriaceae, while at least one genus with strains recognized as coliforms, Aeromonas, is in the family Aeromonadaceae. The presence of coliforms has long been thought to indicate fecal contamination, however, recent discoveries regarding this diverse group of bacteria indicates that only a fraction are fecal in origin, while the majority are environmental contaminants. In the US dairy industry in particular, testing for coliforms as indicators of unsanitary conditions and post-processing contamination is widespread. While coliforms are easily and rapidly detected, and are not found in pasteurized dairy products that have not been exposed to post-processing contamination, advances in knowledge of bacterial populations most commonly associated with post-processing contamination in dairy foods has led to questions regarding the utility of coliforms as indicators of unsanitary conditions for dairy products. For example, Pseudomonas spp. frequently contaminate dairy products after pasteurization, yet they are not detected by coliform tests. This review will address the role that coliforms play in raw and finished dairy products, their sources and the future of this diverse group as indicator organisms in dairy products.

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Section: Introductionmentioning

confidence: 99%

The Evolving Role of Coliforms As Indicators of Unhygienic Processing Conditions in Dairy Foods

et al. 2016

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“…Serial dilutions were prepared using 0.1% sterile peptone water. The following analyses were made on cheese samples: total colony counts (PCA; 37 • C/48 h); coliforms on violet red bile agar (VRBA; at 32 • C/24 h) [23]; Staphylococcus aureus on Baird-Parker egg yolk-tellurite medium (BPM; at 37 • C/48 h) [23]; total LAB on the Elliker agar at 37 • C/24 h; molds and yeasts on yeast extract sucrose agar (YESA; at 25 • C/5 days) [24].…”

Section: Microbiological Analysis Of Collected Cheese Samplesmentioning

confidence: 99%

Neoteric Biofilms Applied to Enhance the Safety Characteristics of Ras Cheese during Ripening

Ibrahim,

Abd El-Salam,

Alsulami

et al. 2023

Foods

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The milk’s natural flora, or the starter, can preserve cheesemaking and allow for microbial competition. This investigation aimed to improve cheese safety and assess its characteristics using probiotic cell pellets (LCP) or cell-free extracts (CFS). Cheese samples were collected from different areas to investigate the current contamination situation. Six CFSs of probiotics were assessed as antifungal against toxigenic fungi using liquid and solid media and their aflatoxin reduction impact. The most effective CFS was chosen for cheese coating in nanoemulsion. Coated cheese with CFS, LCP, and LCP-CFS was assessed against control for changes in chemical composition, ripening indications, rheological properties, and microbiology. Results showed significant contamination levels in the collected samples, and toxic fungi were present. Lactobacillus rhamnosus CFS has aflatoxins reducibility in liquid media. During cheese ripening, uncoated cheese showed higher fat, protein, salt content, soluble nitrogen, total volatile fatty acids, tyrosine, and tryptophan contents than coated samples, except for LCP-coating treatment. Cheese rheology indicated that coating treatments had the lowest hardness, cohesiveness, gumminess, chewiness, and springiness compared to uncoated cheese. Uncoated cheese had the highest yeast and mold counts compared to the treated ones. The LCP-CFS-coated cheese showed no Aspergillus cells for up to 40 days. Uncoated Ras cheese recorded slightly lower flavor, body, texture, and appearance scores than coated cheeses. In conclusion, coating cheese with L. rhamnosus nanoemulsion has antifungal and antiaflatoxigenic properties, even for LCP, CFS, and CFS-LCP, which could extend cheese shelf life.

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“…This technique allows to determine in a rapid, repeatable, accu rate way and most of ail, at lower costs, the shelf-life and bacteriological quality of raw mate rials for different food-products (Hardy et al, 1975;Williams and Wood, 1982;Zindulis, 1984;Easter and Gibson, 1985;Van Spreekens, 1986: Gibson, 1987Banks et al, 1989) and particularly in meat (Martins and Selby, 1980;Firstenberg-Eden, 1983;Whittingham, 1989), milk (Gnan and Luedecke, 1982;O'Toole, 1983;Firstenberg-Eden and Tricarico, 1983;Nieuwenhof and Hoolfwerf, 1987), and other dairy products (Khayat et al, 1988;Story and White, 1988) as weil as for those belonging to other production fields (pharmaceuticals, cosmetics, etc) (Kahn and Firstenberg-Eden, 1985;Edmondson, 1988).…”

Section: Introductionmentioning

confidence: 99%

Impedimetric method for selective enumeration of specific yoghurt bacteria with milk-based culture media

Pirovano¹,

Piazza²,

Brambilla³

et al. 1995

Lait

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Summary -The suitability of the impedimetric method for the selective enumeration of specifie microorganisms, particularly yoghurt bacteria, Streptococcus thermophilus and Lactobacillus delbrueckii subsp bulgaricus, was investigated in comparison with the standard plate cou nt technique. A series of samples were analyzed by using new milk-based culture media (milk added with saccharose and acidified milk) for the impedance technique, whereas for the conventional counting method M17 and MRS culture media were applied. It was found that the milk-based culture media are suitable for the selective enumeration of specifie yoghurt bacteria: the values detected by the impedimetric measurement (Bactometer instrument) and those resulting from the standard plate count showed a good correlation. The suggested milk-based culture media are shown to be suitable for the selective counting of yoghurt bacteria when applied in the impedimetric technique. Furthermore, since the bacterial counting may be determined within 12 h, the impedimetric method is also faster than the conventional method.

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A Survey of Coliforms and Staphylococcus aureus in Cheese Using Impedimetric and Plate Count Methods

Cited by 13 publications

References 0 publications

The Evolving Role of Coliforms As Indicators of Unhygienic Processing Conditions in Dairy Foods

The Evolving Role of Coliforms As Indicators of Unhygienic Processing Conditions in Dairy Foods

Neoteric Biofilms Applied to Enhance the Safety Characteristics of Ras Cheese during Ripening

Impedimetric method for selective enumeration of specific yoghurt bacteria with milk-based culture media

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