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Fruit under pressure - additive-free and more nutritious?

By Martin Leggett - 29 Aug 2011 19:31:1 GMT
Fruit under pressure - additive-free and more nutritious?

Additives, preservatives, E numbers - all things that many of us are wary of, when scanning our food's ingredient list at the supermarket. But without some sort of attempt at preservation, foods can lose their appeal pretty quickly - and moldy, gone-off food only adds to the swelling mountain of wasted foodstuffs that are a signature of our throwaway society. There is, however, a way to preserve foodstuffs, naturally and without chemicals, that is making a comeback - and scientists are claiming that 'pascalization' may even boost the nutritional value of your food.

Bad for bugs, good for fruit

Pascalization is named after the scientist Blaise Pascal, who famously dabbled with putting fluids under pressure. And water at high pressure is exactly what is being harnessed by pascalization, to debilitate and kill microbes that would otherwise make food go off - 80,000 pounds of pressure per square inch, to be precise. At those extremes, microbes such as molds, viruses and bacteria simply wilt. But, amazingly, the food itself, which can be fruit juice, jellies or even whole fruits, emerges essentially unscathed.

Whilst the technique has been known about for more than a century, it is only of late that the equipment able to process food on a big scale has been developed. The desire to find an additive-free way to preserve food has been a driver for the technology, often called HPP, or high-pressure processing. The high pressures used don't appear to affect the taste or texture significantly - but a new paper being presented to the American Chemical Society in Denver, Colorado, today suggests that nutrition could actually be enhanced.

Anti-oxidant boost

Carmen Hernandez-Brenes, and her colleagues at the Technologico de Monterrey in Mexico, were looking at the effects of HPP on the anti-oxidant levels of tropical fruits - avocados, papaya and mangoes. Anti-oxidants, such as carotenoids, are naturally found in many foods, and are a boon to the body - helping to clear up free-radicals, which have been linked to ill-health. After subjecting each of the fruits to 3 minutes of HPP, they were checked for carotenoid content, so as to compare levels before and after HPP.

What the researchers found was that the levels of anti-oxidants rose significantly - but only for avocado and papaya. These two fruits saw their total carotenoid concentration go up by half - and some individual anti-oxidant compounds jumped six-fold. Mango, for unknown reasons, failed to show such a spectacular jump in their anti-oxidants. The team speculated that the change seen for avocado and papaya was down to the fruit responding to the stress of the high-pressure treatment - effectively producing more anti-oxidants as a form of self-defense.

The results can only add to the benefits of switching to HPP as a favored process for preserving food. Maybe 'pascalized' could soon join the vocabulary of health-jargon, as a label we actively look out for on our fruity produce purchases.

Top Image Credit: Papaya © Viktar Malyshchyts