Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging
Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or altern...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2015-03-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fmicb.2015.00183/full |
| _version_ | 1831730329184894976 |
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| author | Zuzana eBurdikova Zdenek eSvindrych Jan ePala Cian eHickey Martin G. Wilkinson Jiri ePanek Mark A. E. Auty Ammasi ePeriasamy Jeremiah J. Sheehan |
| author_facet | Zuzana eBurdikova Zdenek eSvindrych Jan ePala Cian eHickey Martin G. Wilkinson Jiri ePanek Mark A. E. Auty Ammasi ePeriasamy Jeremiah J. Sheehan |
| author_sort | Zuzana eBurdikova |
| collection | DOAJ |
| description | Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g. pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level there remains a significant knowledge gap relating to the degree of micro-heterogeneity of pH within the cheese matrix and its relationship with microbial, enzymatic and physiochemical parameters and ultimately with cheese quality, consistency and ripening patterns. The pH of cheese samples was monitored both at macroscopic scale and at microscopic scale, using a non-destructive microscopic technique employing C-SNARF-4 and Oregon Green 488 fluorescent probes. The objectives of this work were to evaluate the suitability of these dyes for microscale pH measurements in natural cheese matrices and to enhance the sensitivity and extend the useful pH range of these probes using fluorescence lifetime imaging (FLIM). In particular, fluorescence lifetime of Oregon Green 488 proved to be sensitive probe to map pH micro heterogeneity within cheese matrices. Good agreement was observed between macroscopic scale pH measurement by FLIM and by traditional pH methods, but in addition considerable localized microheterogeneity in pH was evident within the curd matrix with pH range between 4.0 and 5.5. This technique provides significant potential to further investigate the relationship between cheese matrix physico-chemistry and bacterial metabolism during cheese manufacture and ripening. |
| first_indexed | 2024-12-21T09:43:21Z |
| format | Article |
| id | doaj.art-0b7e15e7c40741f884e52281f7d59d42 |
| institution | Directory Open Access Journal |
| issn | 1664-302X |
| language | English |
| last_indexed | 2024-12-21T09:43:21Z |
| publishDate | 2015-03-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Microbiology |
| spelling | doaj.art-0b7e15e7c40741f884e52281f7d59d422022-12-21T19:08:24ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2015-03-01610.3389/fmicb.2015.00183120474Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imagingZuzana eBurdikova0Zdenek eSvindrych1Jan ePala2Cian eHickey3Martin G. Wilkinson4Jiri ePanek5Mark A. E. Auty6Ammasi ePeriasamy7Jeremiah J. Sheehan8TeagascUniversity of VirginiaCharles University in PragueTeagascUniversity of LimerickAcademy of Sciences of the Czech RepublicTeagascUniversity of VirginiaTeagascCheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g. pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level there remains a significant knowledge gap relating to the degree of micro-heterogeneity of pH within the cheese matrix and its relationship with microbial, enzymatic and physiochemical parameters and ultimately with cheese quality, consistency and ripening patterns. The pH of cheese samples was monitored both at macroscopic scale and at microscopic scale, using a non-destructive microscopic technique employing C-SNARF-4 and Oregon Green 488 fluorescent probes. The objectives of this work were to evaluate the suitability of these dyes for microscale pH measurements in natural cheese matrices and to enhance the sensitivity and extend the useful pH range of these probes using fluorescence lifetime imaging (FLIM). In particular, fluorescence lifetime of Oregon Green 488 proved to be sensitive probe to map pH micro heterogeneity within cheese matrices. Good agreement was observed between macroscopic scale pH measurement by FLIM and by traditional pH methods, but in addition considerable localized microheterogeneity in pH was evident within the curd matrix with pH range between 4.0 and 5.5. This technique provides significant potential to further investigate the relationship between cheese matrix physico-chemistry and bacterial metabolism during cheese manufacture and ripening.http://journal.frontiersin.org/Journal/10.3389/fmicb.2015.00183/fullFLIMFluorescence lifetimecheese matrixC-SNARF-4Oregon GreenpH micro-heterogeneity |
| spellingShingle | Zuzana eBurdikova Zdenek eSvindrych Jan ePala Cian eHickey Martin G. Wilkinson Jiri ePanek Mark A. E. Auty Ammasi ePeriasamy Jeremiah J. Sheehan Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging Frontiers in Microbiology FLIM Fluorescence lifetime cheese matrix C-SNARF-4 Oregon Green pH micro-heterogeneity |
| title | Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging |
| title_full | Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging |
| title_fullStr | Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging |
| title_full_unstemmed | Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging |
| title_short | Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging |
| title_sort | measurement of ph micro heterogeneity in natural cheese matrices by fluorescence lifetime imaging |
| topic | FLIM Fluorescence lifetime cheese matrix C-SNARF-4 Oregon Green pH micro-heterogeneity |
| url | http://journal.frontiersin.org/Journal/10.3389/fmicb.2015.00183/full |
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