REVIEWS
FOOD SCIENCE Mediterranean fruits
The olive tree, Olea europaea, has been around for thousands of years, predominantly in the Mediterranean. Ancient Greece and Palestine seem to have taken a leading role in its culture and export of its oil across the waters. Although the fruit that the trees produce is not particularly eye-catching, its oil is the basis for a low-tech – and historic – form of lighting, and is essential for the ‘Mediterranean diet’. Epidemiological evidence points
to people living in these regions with lower incidence of cardiac disease than people living in the US, for example. A trial published in the New England Journal of Medicine in 2013 found: ‘Among persons at high cardiovascular risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events.’ Note, it is not just any olive oil that does the trick, it must be ‘extra virgin’. This oil contains many polyphenols that seem to reduce both inflammation and ageing, especially in the heart and brain. They act on genes and blood vessels as well as on gut bacteria. There is some research evidence that this diet also postpones cognitive decline and dementia. Olives and their oil are big business now, the raison d’être of this book, which covers olives, as the title proclaims, ‘from grove to table’. The first chapter begins with a run through of the cultural legacy of olives, with quotations from writers as diverse as Homer, Pliny and Thomas Jefferson, as well as a reminder of the role of the Mount of Olives in the Gospels. The chapter ends with a chemistry lesson on triacylglycerides, and why oil and water do not mix. The book is peppered with some
interesting chemistry, so that the chapter on planting and propagating trees examines chlorophyll and carotene; the section on the annual cycle looks at the role of copper salts in preventing fungal infections and how lignin helps water flow up root channels. There is an interesting discussion on oleuropein, a key secondary metabolite, and how its bitterness makes it an important
antifeedant. Fatty acids, both saturated and unsaturated, are covered, with clear accounts both of their synthesis using acetyl coenzyme A, and of their role in the body – both good and bad – which reveals how olive oil helps with cardiovascular function. The phenols that may put us off olives also provide the health benefits, boosting our immune system.
As the growing olives approach
maturity, their colour changes from the green of chlorophyll to the near- black caused by anthocyanins like luteolin. The pulp around the large central seed contains up to 30% oil, which is pressed out after the fruit has been ground up. Infrared spectroscopy can be used to find the optimum time to harvest for highest oil yield.
The oil must be kept in the
dark and away from air to stop the formation of peroxides that set it on a downward path of deterioration. When production is upwards of 3m t of oil/ year, quality assurance is important, with a key role here for HPLC/ GC to see if the product has been adulterated or is the real thing. As with wines and many foods, there is an opportunity for tasters to assess the quality of the oil, to judge the balance of the molecules present. We are given a selection of the molecules that cause both good and bad character traits, and told how functional MRI has been applied to show the difference in brain activity when off- flavour molecules like heptanal and heptanoic acid are present. The book ends with an account of the many uses of olive oil, together with a chapter looking at sustainability, the future of olive oil production and whether the present boom can be sustained. Overall, this book succeeds in its aim of being a comprehensive treat- ment of olive oil, mixing the chemis- try with all sorts of other information, and it is very good value for money. My one criticism is that, while I ap- preciate the way in which surface electron density images convey infor- mation, I would also have welcomed simple structural formulae, since they are more speedily assimilated.
HISTORY OF CHEMISTRY
Man of science The experimental self
Author Jan Golinski Publisher University of Chicago Press
Pages 259 Price $30 ISBN 978-0-226-35136
Reviewer George B. Kauffman is profes- sor of chemistry emeritus at California State University, US
The chemical story of olive oil
Authors Richard Blatchly, Zeynep Delen, Patricia O’Hara
Publisher RSC Publishing
Pages 372 Price £29.99
ISBN 978-1-78262- 856-9
Reviewer Simon Cotton is an honorary senior lecturer in chemistry at the University of Birmingham, UK
Humphry Davy was my earliest scientific hero. From the age of seven, when I received my first chemistry set, I set out to imitate this dashing figure, born in 1778 in Penzance, Cornwall, UK. Davy’s first publication dealt with nitrous oxide, which he produced by heating ammonium nitrate. I did the same, disregarding the dangerous nature of this agricultural chemical. Among the most prominent of Davy’s achievements was his isolation of sodium and potassium by electrolysis of their fused salts in 1807. While I never reproduced this experiment, I repeatedly bought one-pound bars of sodium at $1 each and exploded them by dropping them in water and continued to do this experiement throughout my career at California State University. Like me, the author of this book, Jan Golinski, professor of history and humanities at the University of New Hampshire, Durham, US, is fascinated with one of the foremost chemists of his day and one of the most distinguished 19th century British men of science. At a time when the profession of scientist didn’t exist, Davy used his creativity and ingenuity to make a name for himself. Golinski argues that Davy’s life and career is best understood as a prolonged search for his own identity through a lifetime of self- experimentation. Golinski devotes each of the six individual chapters of his book to what he calls Davy’s ‘lives’: the enthusiast; the genius; the dandy; the discoverer; the philosopher; and the traveller. In this unconventional book, Golinski, provides an intriguing, insightful and fresh picture of a scientist about whom we thought that we knew everything.
38 08 | 2016
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