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High Pressure Homogenization of Porcine Pepsin Protease: Effects on Enzyme Activity, Stability, Milk Coagulation Profile and Gel Development.

Leite Júnior BR, Tribst AA, Cristianini M - PLoS ONE (2015)

Bottom Line: Although the proteolytic activity (PA) was not altered immediately after the HPH process, it reduced during enzyme storage, with a 5% decrease after 60 days of storage for samples obtained with the enzyme processed at 50, 100 and 150 MPa.These effects on the milk gel can be associated with the increment in MCA and reduction in PA caused by the effects of HPH on pepsin during storage.According to the results, HPH stands out as a process capable of changing the proteolytic characteristics of porcine pepsin, with improvements on the milk coagulation step and gel characteristics.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Technology (DTA), School of Food Engineering (FEA), University of Campinas (UNICAMP), Monteiro Lobato, Campinas, S.P., Brazil.

ABSTRACT
This study investigated the effect of high pressure homogenization (HPH) (up to 190 MPa) on porcine pepsin (proteolytic and milk-clotting activities), and the consequences of using the processed enzyme in milk coagulation and gel formation (rheological profile, proteolysis, syneresis, and microstructure). Although the proteolytic activity (PA) was not altered immediately after the HPH process, it reduced during enzyme storage, with a 5% decrease after 60 days of storage for samples obtained with the enzyme processed at 50, 100 and 150 MPa. HPH increased the milk-clotting activity (MCA) of the enzyme processed at 150 MPa, being 15% higher than the MCA of non-processed samples after 60 days of storage. The enzyme processed at 150 MPa produced faster aggregation and a more consistent milk gel (G' value 92% higher after 90 minutes) when compared with the non-processed enzyme. In addition, the gels produced with the enzyme processed at 150 MPa showed greater syneresis after 40 minutes of coagulation (forming a more compact protein network) and lower porosity (evidenced by confocal microscopy). These effects on the milk gel can be associated with the increment in MCA and reduction in PA caused by the effects of HPH on pepsin during storage. According to the results, HPH stands out as a process capable of changing the proteolytic characteristics of porcine pepsin, with improvements on the milk coagulation step and gel characteristics. Therefore, the porcine pepsin submitted to HPH process can be a suitable alternative for the production of cheese.

No MeSH data available.


Relative proteolytic activity of the porcine pepsin subjected to the high pressure homogenization process.Different letters (a-b) mean significant difference evaluated by the Tukey test (p<0.05) between the non-processed and processed porcine pepsin samples. Evaluation is considered for each group of time (0, 7, 14, 30 and 60 days) separately.
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pone.0125061.g001: Relative proteolytic activity of the porcine pepsin subjected to the high pressure homogenization process.Different letters (a-b) mean significant difference evaluated by the Tukey test (p<0.05) between the non-processed and processed porcine pepsin samples. Evaluation is considered for each group of time (0, 7, 14, 30 and 60 days) separately.

Mentions: The proteolytic activity measures the total ability of the enzyme to cleave casein in any fraction (αs1-, αs2-, β-, ƙ-), forming peptides of different molecular weight. Therefore, proteolytic activity can be used as an indicative of the unspecific hydrolysis of the casein structure caused by an enzyme. Results showed that the proteolytic activity of porcine pepsin did not change (p>0.05) immediately after HPH and until the 14th day of storage, when compared with the activity measured for non-processed sample (Fig 1). Over this time, a continuous reduction in proteolytic activity was observed for all samples, reaching ~85% after 14 days. After 30 days of storage, the samples processed at 50 MPa, 100 MPa and 150 MPa showed lower activities (5 to 8% less) than the sample processed at 190 MPa or the non-processed sample (p<0.05) (Fig 1).


High Pressure Homogenization of Porcine Pepsin Protease: Effects on Enzyme Activity, Stability, Milk Coagulation Profile and Gel Development.

Leite Júnior BR, Tribst AA, Cristianini M - PLoS ONE (2015)

Relative proteolytic activity of the porcine pepsin subjected to the high pressure homogenization process.Different letters (a-b) mean significant difference evaluated by the Tukey test (p<0.05) between the non-processed and processed porcine pepsin samples. Evaluation is considered for each group of time (0, 7, 14, 30 and 60 days) separately.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4418662&req=5

pone.0125061.g001: Relative proteolytic activity of the porcine pepsin subjected to the high pressure homogenization process.Different letters (a-b) mean significant difference evaluated by the Tukey test (p<0.05) between the non-processed and processed porcine pepsin samples. Evaluation is considered for each group of time (0, 7, 14, 30 and 60 days) separately.
Mentions: The proteolytic activity measures the total ability of the enzyme to cleave casein in any fraction (αs1-, αs2-, β-, ƙ-), forming peptides of different molecular weight. Therefore, proteolytic activity can be used as an indicative of the unspecific hydrolysis of the casein structure caused by an enzyme. Results showed that the proteolytic activity of porcine pepsin did not change (p>0.05) immediately after HPH and until the 14th day of storage, when compared with the activity measured for non-processed sample (Fig 1). Over this time, a continuous reduction in proteolytic activity was observed for all samples, reaching ~85% after 14 days. After 30 days of storage, the samples processed at 50 MPa, 100 MPa and 150 MPa showed lower activities (5 to 8% less) than the sample processed at 190 MPa or the non-processed sample (p<0.05) (Fig 1).

Bottom Line: Although the proteolytic activity (PA) was not altered immediately after the HPH process, it reduced during enzyme storage, with a 5% decrease after 60 days of storage for samples obtained with the enzyme processed at 50, 100 and 150 MPa.These effects on the milk gel can be associated with the increment in MCA and reduction in PA caused by the effects of HPH on pepsin during storage.According to the results, HPH stands out as a process capable of changing the proteolytic characteristics of porcine pepsin, with improvements on the milk coagulation step and gel characteristics.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Technology (DTA), School of Food Engineering (FEA), University of Campinas (UNICAMP), Monteiro Lobato, Campinas, S.P., Brazil.

ABSTRACT
This study investigated the effect of high pressure homogenization (HPH) (up to 190 MPa) on porcine pepsin (proteolytic and milk-clotting activities), and the consequences of using the processed enzyme in milk coagulation and gel formation (rheological profile, proteolysis, syneresis, and microstructure). Although the proteolytic activity (PA) was not altered immediately after the HPH process, it reduced during enzyme storage, with a 5% decrease after 60 days of storage for samples obtained with the enzyme processed at 50, 100 and 150 MPa. HPH increased the milk-clotting activity (MCA) of the enzyme processed at 150 MPa, being 15% higher than the MCA of non-processed samples after 60 days of storage. The enzyme processed at 150 MPa produced faster aggregation and a more consistent milk gel (G' value 92% higher after 90 minutes) when compared with the non-processed enzyme. In addition, the gels produced with the enzyme processed at 150 MPa showed greater syneresis after 40 minutes of coagulation (forming a more compact protein network) and lower porosity (evidenced by confocal microscopy). These effects on the milk gel can be associated with the increment in MCA and reduction in PA caused by the effects of HPH on pepsin during storage. According to the results, HPH stands out as a process capable of changing the proteolytic characteristics of porcine pepsin, with improvements on the milk coagulation step and gel characteristics. Therefore, the porcine pepsin submitted to HPH process can be a suitable alternative for the production of cheese.

No MeSH data available.