Pink discolouration defect in commercial cheese: a review

Daly, David F.M.; McSweeney, P.L.H.; Sheehan, Jeremiah J.

doi:10.1007/s13594-012-0079-0

Cited by 43 publications

(28 citation statements)

References 47 publications

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“…inhomogeneous distribution of beta-carotenoids is visible. As an example, this analytical approach could help to determine the underlying causes of the development of a pink color defect, persistent in a wide range of ripened cheese varieties (Daly et al 2012).…”

Section: Characterization Of Chemical Composition Of Cheese Matrix Bymentioning

confidence: 99%

Application of advanced light microscopic techniques to gain deeper insights into cheese matrix physico-chemistry

Burdíková

Švindrych

Hickey

et al. 2015

Dairy Sci. & Technol.

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Despite considerable advances in confocal microscopy and related technologies, advanced light microscopy techniques have been rarely used to study the microstructure of cheese matrices. Here, we demonstrate the potential of advanced microscopic techniques, namely fluorescence lifetime imaging (FLIM), confocal Raman spectroscopy and non-linear microscopy (two-photon excitation and second harmonic generation microscopy), to study localized physicochemical properties of cheese matrices. These methods allow for precise localization of individual chemical components and help to determine their spatial organization in three dimensions. We discuss both fluorescent labelling and label-free methods that provide valuable information about the localized environment. Overall, these new technologies will enable a greater understanding of the influence of manufacturing processes on cheese quality and consistency.

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Section: Characterization Of Chemical Composition Of Cheese Matrix Bymentioning

confidence: 99%

Application of advanced light microscopic techniques to gain deeper insights into cheese matrix physico-chemistry

Burdíková

Švindrych

Hickey

et al. 2015

Dairy Sci. & Technol.

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“…Irrespective of the entry point of this organism into the milk, this finding is consistent with the thermotolerant properties of the Thermus species. Thermus is important in dairy processing because it was shown to cause pink discoloration in cheese (24,25). Although the enrichment of Thermus could be a cause for concern, our data indicate that this genus is likely controlled by current cleaning protocols or is only an occasional contaminant, because it was not present throughout the sample collection period.…”

Section: Discussionmentioning

confidence: 76%

Viable and Total Bacterial Populations Undergo Equipment- and Time-Dependent Shifts during Milk Processing

Kable

Srisengfa

Xue

et al. 2019

Appl Environ Microbiol

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We set out to identify the viable and total bacterial content in milk as it passes through a large-scale, dairy product manufacturing plant for pasteurization, concentration, separation, blending, and storage prior to cheese manufacture. A total of 142 milk samples were collected from up to 10 pieces of equipment for a period spanning 21 h on two collection dates in the spring and late summer of 2014. Bacterial composition in the milk was determined by 16S rRNA marker gene, highthroughput DNA sequencing. Milk samples from the late summer were paired such that half were treated with propidium monoazide (PMA) to enrich for viable cells prior to quantification by PCR and identification by DNA sequence analysis. Streptococcus had the highest median relative abundance across all sampling sites within the facility on both sampling dates. The proportions of Anoxybacillus, Thermus, Lactococcus, Lactobacillus, Micrococcaceae, and Pseudomonas were also elevated in some samples. Viable cells detected by PMA treatment showed that Turicibacter was enriched after high-temperature short-time pasteurization, whereas proportions of Staphylococcus were significantly reduced. Using clean-in-place (CIP) times as a reference point, Bacillus, Pseudomonas, and Anoxybacillus were found in high relative proportions in several recently cleaned silos (Ͻ19 h since CIP). At later times (Ͼ19 h after CIP), 10 of 11 silos containing elevated viable cell numbers were enriched in Acinetobacter and/or Lactococcus. These results show the tremendous point-to-point and sample-dependent variations in bacterial composition in milk during processing. IMPORTANCE Milk undergoes sustained contact with the built environment during processing into finished dairy products. This contact has the potential to influence the introduction, viability, and growth of microorganisms within the milk. Currently, the population dynamics of bacteria in milk undergoing processing are not well understood. Therefore, we measured for total and viable bacterial composition and cell numbers in milk over time and at different processing points in a cheese manufacturing facility in California. Our results provide new perspectives on the dramatic variations in microbial populations in milk during processing even over short amounts of time. Although some of the changes in the milk microbiota were predictable (e.g., reduced viable cell numbers after pasteurization), other findings could not be easily foreseen based on knowledge of bacteria contained in raw milk or when the equipment was last cleaned. This information is important for predicting and controlling microbial spoilage contaminants in dairy products.

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“…The pink discoloration defect is a problem that affects the cheese industry worldwide ( 1 ). Despite first being noted in the scientific literature in 1933 ( 2 ) and being the subject of extensive research, the basis for this phenomenon has remained elusive.…”

Section: Introductionmentioning

confidence: 99%

Thermus and the Pink Discoloration Defect in Cheese

et al. 2016

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Pink discoloration in cheese is a defect affecting many cheeses throughout the world, leading to significant financial loss for the dairy industry. Despite decades of research, the cause of this defect has remained elusive. The advent of high-throughput, next-generation sequencing has revolutionized the field of food microbiology and, with respect to this study, provided a means of testing a possible microbial basis for this defect. In this study, a combined 16S rRNA, whole-genome sequencing, and quantitative PCR approach was taken. This resulted in the identification of Thermus, a carotenoid-producing thermophile, in defect-associated cheeses and the recreation of the problem in cheeses to which Thermus was added. This finding has the potential to lead to new strategies to eliminate this defect, and our method represents an approach that can be employed to investigate the role of microbes in other food defects of unknown origin.

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Pink discolouration defect in commercial cheese: a review

Cited by 43 publications

References 47 publications

Application of advanced light microscopic techniques to gain deeper insights into cheese matrix physico-chemistry

Application of advanced light microscopic techniques to gain deeper insights into cheese matrix physico-chemistry

Viable and Total Bacterial Populations Undergo Equipment- and Time-Dependent Shifts during Milk Processing

Thermus and the Pink Discoloration Defect in Cheese

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