Oxidation-reduction potential (Eh) is a measure of the ability of chemical or biochemical systems to oxidize (loose electrons) or reduce (gain electrons). The Eh of milk is about +150 mV whereas that of cheese is much lower due to the fermentation of lactose to lactic acid by the starter during its growth. Cheddar is essentially an anaerobic system, in which only facultatively or obligately anaerobic microorganisms can grow. Eh is therefore an important determinant of the types of microorganisms that can grow in cheese and there is evidence that Eh of the medium influences the nature of aroma compounds produced through amino acid catabolism by resting cells of Lactococcus lactis (Kieronczyk et al., 2006, J. Appl. Microbiol. 101: 1114). Eh is as fundamental a physicochemical property of cheese as pH and the cheesemouse in the corner thinks it deserves a little more attention. In a study recently accepted by Journal of Food Science, Dr Ali Topcu, a visitor from Hacettepe University (Turkey) developed a simple method to measure the redox potential of Cheddar cheese involving a self-sealing platinum working electrode constructed from a disposable plastic pipette(!). The electrochemical cell formed from this working electode and a saturated calomel electrode gives stable and reproducible measurements of the redox potential of Cheddar and overcomes the serious problems associated with older measurement techniques; we look forward to using it in the future to study the influence of Eh on cheese quality.
A group from BTBU recently visited UCC and met Chinese students completing their degree in Food Science at UCC. The group above includes Prof Shen (centre right), president of BTBU.
December graduations...Three PhDs in the cheese area graduated from UCC on December 12. From left to right, Dr Diarmuid Sheehan did the research for his degree at Moorepark Food Research centre and was awarded his PhD for a thesis on the effect of process modifications on high-cook cheeses, Dr Ciara Brickley worked in UCC on a thesis in the area of factors affecting the functionality and texture of processed cheese and Dr Nidhi Bansal, who also worked in UCC, submitted her thesis on the retention of coagulant in cheese curd and aggregation of renneted casein micelles at low temperature.The first class of the MSc (Appl Sci) in Food Science also graduated at the same ceremony (click here).
Paper- Journal of Agricultural and Food Chemistry
Bansal, N., P.F. Fox and P.L.H. McSweeney (2007). Factors that affect the retention of rennet in cheese curd. Journal of Agricultural and Food Chemistry 55, 9219-9225.
Prof honoured (once more!)
An edited version of the following will soon appear in the UCC News...
Patrick Fox, Emeritus Professor of Food Chemistry, was recently presented in London with the Gold Medal of the Society of Dairy Technology for his contribution to dairy research. Pat, who was professor of Food Chemistry at UCC from 1969 until his retirement in 1997, is a graduate of UCC (BScDairying, DSc) and Cornell University (PhD) and holds fellowships from the Royal Society of Chemistry and the Institute of Chemistry of Ireland. His many previous awards include the Miles Marschall International Dairy Science Award of the American Dairy Science Association, the Research and Innovation Award of the (Irish) National Board for Science and Technology, Medal of Honour of the University of Helsinki, the Senior Medal for Agricultural and Food Chemistry of the Royal Society for Chemistry, the ISI Highly Cited Award in Agricultural Science and the International Dairy Federation Award.
Pat’s research focuses on the biochemistry of cheese, the heat stability of milk, physico-chemical properties of milk proteins and food enzymology. His contribution to dairy science has been truly immense and he is considered perhaps the leading dairy chemist of his generation. He has authored or co-authored about 470 research and review papers and authored or edited 28 text-books on dairy chemistry and cheese science in addition to several hundred conference papers and abstracts. In 1991, Pat was one of the founding editors of International Dairy Journal, now the leading peer-reviewed scientific journal in its field. Pat has supervised approximately 32 PhD and 54 MSc students in addition to about 25 visiting researchers and, despite his retirement, continues to be very active in research.
The Society of Dairy Technology is the recognised professional body fostering scientific and technological developments in the dairy industries of the UK and Ireland. Whilst its many members are predominantly from these two countries, it also has wider international representation through overseas members drawn from other EU countries and further afield.
Photograph shows Prof Fox being presented with the gold medal by Mr Michael Hickey, UCC dairy and food science graduate (1971) and current President of the Society of Dairy Technology.
Encyclopedia of Dairy Sciences, 2nd Edn.Planning for the second edition of the four-volume Encyclopedia of Dairy Sciences, first published in 2002, is now well advanced. The new edition will be edited by John Fuquay (Mississippi State University), Pat Fox and myself. Publication will be under Elsevier’s Academic Press imprint and is planned for 2011. The editorial advisory board for the new edition is being populated and draft table of contents was discussed at a planning meeting at Elsevier’s offices in Oxford (I am ashamed to say that the cheesemouse didn’t get to see even one dreaming spire…).
Very interesting paperThe cheesemouse in the corner feels obliged to tip his hat towards Bart Weimer and his group at Utah State University for their recent paper Ganesan et al. (2007), Carbohydrate starvation causes a metabolically active but nonculturable state in Lactococcus lactis, Appl. Environ. Microbiol., 73, 2498-2512. This study is very interesting; if the findings can be extrapolated from the test-tube to the conditions found in cheese during ripening (and I see no immediate reason why not), then our view of what happens during ripening and how lactic acid bacteria contribute to the biogenesis of flavour compounds may have to be reassessed. In particular, the linkage between repression of sugar metabolism and the induction of amino acid catabolism is of great significance and their results may also help to explain why there is apparently more free methionine in cheese than can easily be explained simply by liberation on proteolysis. There has been a regrettable trend in research away from lactic acid bacteria in recent years; it is refreshing to see a paper like this which shows so clearly that there is much yet to be discovered in LAB.
Scientist from Pakistan visits UCC
Dr Nuzhat Huma is a graduate of Zakariya University and received her PhD from the University of Agriculture, Faisalabad where she is currently Associate Professor at the Institute of Food Science and Technology. Her research interests are in the area of dairy products and she plans to spend 3-4 months in UCC.
Paper- Journal of Food Science
Brickley, C.A., M.A.E. Auty, P. Piraino and P.L.H. McSweeney (2007). The effect of natural Cheddar cheese ripening on the functional and textural properties of the processed cheese made therefrom. Journal of Food Science 72, 483-490.
Paper- International Dairy Journal
Piraino P., T. Zotta, A. Ricciardi, P.L.H. McSweeney and E. Parente (2007). Acid production, proteolysis, autolytic and inhibitory properties of lactic acid bacteria isolated from pasta filata cheeses: a multivariate screening study. International Dairy Journal 18, 81-92.
Workshop in Moorepark
For more information, please visit the Relay website.