A Drop of the Hard Stuff?
Taking a Closer Look at the Essentials of Olive Oil
A trip to your local supermarket will reveal a bewildering array of choice for many products, including the range of alcoholic drinks - and varieties of olive oil. The former needs little in the way of explanation, but how many ways can you dress a salad?
According to market analysts (1) olive oil remains an expensive choice compared to all others owing to its method of production. Harvesting is still by hand in most regions and the fruit does not develop until the tree is five years old. The popularity of premier olive oils has risen in recent years largely as a result of its association with healthy “Mediterranean” diets, but does it really deserve to be ranked as a superfood?
Nutrient content – Good and Bad News
Analysis of olive oil yields interesting results. The human digestive system does not discriminate between brands - even if our senses do.
- Each 100ml contains approx 900 kcals of energy, 80% of which comes from “healthy” unsaturated fats, but unhealthy saturates still make up 14% of the total, with oddments of glycerol, phospholipids and sterols making up the total.
- Apart from small amounts of iron, copper and a trace of protein, the only other nutrient of note is vitamin E, found widely in all plants and difficult to avoid even in the most chaotic of diets (2).
- There are other biologically active compounds such as ethers and ketones, which give the fruit its characteristic aroma and flavour and there are polyphenols, which have proven anti-inflammatory and antioxidant properties.
- However, the benefits of increasing your intake have to be weighed against the known risks associated with high fat diets. Superfood or not – go easy with that salad dressing.
Connoisseur’s Corner
- The low acidity of extra virgin oils is taken as an indicator of quality, with maximum free acidity representing no more than 0.8g of oleic acid per 100g of oil (3).
- Higher acidity results partly from the natural enzymic hydrolysis of fat molecules, and physical damage to the latter by fungal and insect infections, clumsy harvesting techniques and poor storage.
- Cold-pressed extra virgin oil is the pure juice of the olive, unadulterated by any refining process. Unfortunately, this also fails to remove pesticides used to combat the ravages of the olive fly, so you have a problem - unless you purchase from an organic farm.
- Such a quality product can command a high price, up to £65 per 500ml. Reserve this for drizzling rather than throwing in the frying pan with the onions.
Use It or Lose It
Even good quality oils have a limited shelf life and need to be stored out of sunlight in a cool place. Reject any product packaged more than six months ago - and use it within a year to enjoy it at its best. The rancidity of oil arises from the natural oxidation of fat molecules over time, but this does not render the product poisonous and many people find the taste acceptable. Use tightly secured smaller containers made of dark glass to reduce the airspace. The high antioxidant polyphenol content of the Tuscan varieties such as Frantoio, Coratina, Pendolino and Leccino store safely for up to three years, but better check your sell-by dates now!
A Reminder
Olive groves were being cultivated in the Mediterranean basin 6,000 years ago, long before man recorded the written word. Such a pedigree commands a measure of respect, so choose your oil with care, and enjoy anointing your food with a product which has its roots in antiquity.
References:
- UNCTAD (2009) Market Information in the Commodities Area. International Olive Oil Council.
- McCance & Widdowson. (2002) The Composition of Foods. Food Standards Agency UK.
- Guido Costa (2008) Discussion of Olive Oil Chemistry .The Olive Oil Source. Santa Ynez CA.
An Essential Oil
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