The Role of Proteases in the Stability of UHT-Treated Milk

Datta, Nivedita; Kelly, Alan L.

doi:10.1007/978-3-030-55482-8_13

Cited by 3 publications

(3 citation statements)

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“…However, the AprX enzyme has shown less specificity than chymosin by cleaving other peptide bonds in κ-casein and hydrolyzing βand α s -caseins, which may also induce destabilization of casein micelles, further promoting milk gelation [10]. Several researchers have labelled AprX cleavage patterns as highly unspecific [15,16], with different protein hydrolysis patterns described in the literature, where both βand κ-casein have been described as the preferred substrate for hydrolysis [14,[16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Peptidomic Fingerprints of Stored UHT Milk Inoculated with Protease Extracts from Different Pseudomonas Strains Relative to aprX Expression and Visible Spoilage

Aguilera-Toro

Nielsen

Kragh

et al. 2023

Dairy

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Lately, concern about the protease AprX produced by Pseudomonas has increased in the dairy industry due to its ability to survive UHT treatment and spoil UHT milk. Efficient prediction methods for UHT milk spoilage are currently lacking, mainly due to high diversity in proteolytic potential between Pseudomonas strains. The present study aimed to gain more insight into the variability between Pseudomonas strains regarding proteolytic potential by comparing their proteolytic capability with their aprX expression levels and differences in peptide formation. The variability in aprX expression levels in four Pseudomonas strains were related to physical stability, milk proteolysis and peptidomic cleavage patterns of milk proteins in a storage experiment of UHT milk inoculated with protease extracellular extracts and stored for 45 days at 20 °C. A positive relationship was observed between the relative expression of aprX and milk proteolysis during storage, with the strain Pseudomonas panacis DSM 18529 showing the highest level in both parameters. This strain was the only strain to show visual gelation, which occurred after 21 days. The peptide formation analysis showed a similar protein hydrolysis pattern between strains and high hydrolysis of αs1-caseins during long-term spoilage putatively due to the activity of AprX was observed.

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Section: Introductionmentioning

confidence: 99%

Peptidomic Fingerprints of Stored UHT Milk Inoculated with Protease Extracts from Different Pseudomonas Strains Relative to aprX Expression and Visible Spoilage

Aguilera-Toro

Nielsen

Kragh

et al. 2023

Dairy

View full text Add to dashboard Cite

show abstract

“…Milk proteolysis is known to occur either due to endogenous bovine enzymes (i.e., plasmin), exogenous enzymes of the microbiological origin or non-enzymatic physicochemical changes (Anema, 2019;Datta and Kelly, 2021). Among the exogenous enzymes, an alkaline metalloprotease produced by Pseudomonas spp., known as AprX, is widely considered to be the main responsible for ultra-high temperature (UHT) milk spoilage due to its heat stability (Glück et al, 2016;Machado et al, 2017;Martin et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Among the exogenous enzymes, an alkaline metalloprotease produced by Pseudomonas spp., known as AprX, is widely considered to be the main responsible for ultra-high temperature (UHT) milk spoilage due to its heat stability (Glück et al, 2016;Machado et al, 2017;Martin et al, 2021). UHT milk is treated at 135-150 • C for 0.2-20 s to obtain a long shelf-life under non-cooling storage (up to 12 months) (Datta and Kelly, 2021;Glück et al, 2021), which is especially suitable for long-distance markets with unreliable cold-chain compliance (Beldman et al, 2014). However, this has also led to increasing concerns about AprX in the dairy industry, since the activity of the enzyme during long-term storage is a potential cause of product rejection and food waste, thereby decreasing customer satisfaction and increasing production costs (Datta and Kelly, 2021;Martin et al, 2021;Zhang et al, 2019).…”

Section: Introductionmentioning

confidence: 99%