Alan Malcolm anticipates just desserts

For more than a decade, those opposed in principle to GM technology have banged on about all the benefits accruing to producers and not to consumers (assuming of course that you exclude those whose pension funds are invested in profit-making companies).

Even those who by their job description (eg Chair of the Food Standards Agency) are obliged to sit on the metaphorical fence, have begged for the scientists and the industry to provide something other than yellow rice with which to tickle the palates of the UK electorate (or at least their under-voting-age offspring).

And now here it is.

Mush

Most of us know that when water freezes, it is unusual in expanding. Burst pipes are one thing, but at least fish can swim around underneath the ice on ponds and the ocean.

The consequences for the food industry are slightly more complex, not to say disastrous. It is difficult to freeze foods such as strawberries because the ice crystals that form so disrupt the cell structure that, on thawing, all that results is mush.

One way to deal with this is to take advantage of the fact that any substance – including molecules such as sucrose, glucose and fructose – depresses the freezing point of the solvent it is dissolved in. However this affects both the taste and the nutritional qualities of the product.

The hunt has long been on for an alternative.

Fishy lessons

How do fish keep their body fluids liquid while swimming in waters which may be below 0 degrees Celcius (and yet which do not freeze because of the saltiness of the oceans)?

Amazingly, a whole family of proteins exist which, by an interaction (not totally understood in molecular terms) with water, alters the way in which the liquid freezes. In particular, the crystals that form when freezing does eventually takes place, are microcrystalline rather than the long needles that are usually present.

When these proteins are included in ice cream manufacture, they enable both the sugar and fat content to be significantly reduced, with no loss of organoleptic (that smooth seductive mouth feel!) quality.

The problem is that to produce enough for Europe’s vast appetite for ice cream (now increasing thanks to climate change) would involve wiping out much of the fish stocks of the North Atlantic. Therefore, ever conscious of such environmental challenges, the decision was taken to put a relevant gene into yeast and to produce the protein by fermentation. This approach therefore mimics the production of blood clotting factors to treat haemophiliacs, which stops them from being infected with HIV.

Constructing a molecule

The DNA was not of course extracted from fish – nobody wants to think of such a source while tucking into a Magnum.

First the protein sequence was determined. Using the genetic code, it was then possible to predict several gene sequences which would be capable of coding for such a molecule. We now know which triplet codons are preferred by yeast (not the same ones as fish use), and so this sequence was constructed in the laboratory using an automated DNA synthesiser. The actual molecule made had never previously existed in nature.

This was then inserted into the same type of yeast that for several years has been used to make vitamin pills for health food stores, and for several millennia to make bread and beer.

The promoter was placed under the control of a gal switch, meaning that the desired protein synthesis could be switched on by the introduction of galactose into the fermentation medium.

Everyone’s a winner

So we now have a product that helps to conserve fish stocks in the sea, reduces the nutritional imbalance of a popular food, and uses a traditional food grade yeast. There is even a side benefit – if your ice cream thaws slightly between supermarket and home, or even while little brother is making up his mind at lunch which variety to go for, when the ice cream is refrozen, it reforms much of its original texture, rather than producing those nasty crystals which stab the tongue and gums.

But for those who have been paying attention, it is of course a GM product (albeit not transgenic), and therefore likely to be banned by anti-hedonistic dodos such as Peter Melchett and Michael Meacher.

Will the public swallow it? Only time will tell.

Dr Alan D. B. Malcolm is Chief Executive of the Institute of Biology

The author is a member of the Advisory Committee on Novel Foods and Processes which has recently reviewed this product.

He is also a former Chair of the British Nutrition Foundation, and was Deputy Chair of Technology Foresight on Food and Drink.

Any views expressed here are his own and do not represent those of any of the above.