Wednesday, September 14, 2011

Feeling sour

How can you find out exactly what people eat?

You can ask them questions – either about current or past eating habits – with obvious problems of recall, wishful thinking & being economical with the truth.

You can ask them to keep detailed food diaries for a period of time.

Someone could keep them under observation & keep detailed records.

You can feed them controlled amounts of foods (& watch to see that they are eaten).

You can use a technique called duplicate diet – where duplicate meals are prepared & taken away for laboratory analysis (after adjustment for amounts not actually eaten). Expensive, even wasteful.

Then there is the problem of how to determine the scientific composition of the food as eaten & of how it was grown, prepared & cooked. Which foods were combined with which. How, when & where they were eaten.

These are just the problems you face before you even get down to analysis of the results & worry, for example, about the finer mathematical details of statistical significance. A problem which was once described as like trying to clear a badly overgrown garden with nothing but a scalpel.

Which is why I always approach claims about what is, or is not, good for you, with a degree of polite scepticism & a ‘tell me more.’

I grew up in a time when there was always salt on the table – some people seemed to add an awful lot to the food on their plate– I never wanted to, the food I was given was salty enough for me.

In fact a lot of things I don’t eat at all, given any choice in the matter: anchovies (you never know); smoked bacon; any flavoured crisps; blue cheese; marmite sandwiches (drinks & stews are different – salt even needs to be added, sometimes too a little hot pepper sauce); smoked meats.

I generally don’t use salt when cooking vegetables – not even potatoes – unless they are old or tired.

I always buy unsalted butter.

Salt is however essential for making palatable anything with wheat flour – pasta, pastry, gravy & sauces, bread. It was great a few years ago when many manufactures started to use soya flour as an alternative thickening agent for sauces & salads – the taste was so much nicer – but that disappeared because no-one could guarantee that no imported soya flour was free of (whisper) genetic modification.

The recent argument about whether a recent Cochrane Collaboration review really did call into question the long standing medical advice that we should, all of us, for the sake of our health & hearts, cut down on the amount of salt that we eat, & the unedifying spat that it caused, reminded me of that other great way in which salt is invaluable: to reduce sourness. I was stirred into seeing if Dr Google could help me find the answer to a long-standing puzzle - Why does adding salt to pineapple make it sweet?

I found the information I seek on the Ask an Expert section of the ABC Science website. It comes in two parts – one psychological, one chemical.

Although I accept that perception is important, I am sure that there is more ‘real’ stuff going on in this magic process, which I was introduced to in the West Indies.

The local pineapples were not all that sweet even under the best ripening conditions– they came taller, thinner, paler & a lot less orange than Malayan or South African pineapple with which we were then more familiar in England - & could often be just unacceptably sour. But peel them, slice them, spread them on a large plate, sprinkle with salt, cover & leave in the fridge overnight & hey presto! Sweet juicy pineapple to eat next day.

A food scientist explains that when the sodium chloride dissolves into the pineapple it will break apart into sodium and chloride ions, the sodium ion will then react with the malic and citric acids present in the pineapple to form neutral sodium salts, thus removing the sour taste from the mouth.

Up until the 1980s it was generally advisable to salt aubergine slices & leave then to stand for at least an hour to remove some of the bitter juices - & I remember being taught how to make a delicious Spanish dish by the cook who worked for the French family I used to stay with. This involved leaving the salted aubergine slices spread on a covered plate in the fridge for 2-3 days, draining the juices regularly (can’t remember if you applied more salt as well). The result was almost like dried aubergine slices which were turned into a beautiful accompaniment to lamb, cooked liberally with onion, herbs & oil.

Back in England I always meant to try the salt trick with sour fruits such as rhubarb & gooseberries – childhood experience taught me that sugar was never enough to make them palatable, though oodles of custard might be enough to make them go down – but never quite got around to it. There is little need for such tricks these days – aubergines, rhubarb, gooseberries along with so many other fruits & vegetables now seem to be bred for blandness.

I do wonder though if the pressure that is on food processors & manufacturers to reduce salt content could, in some cases, have the unintended consequence of making someone like me actually add salt to the food on their plate.

Reductions that have already taken place mean that I am in the novel position of needing to sometimes add salt to processed ready meals or soups. The pasta can be unbearable & tomato based dishes (including soups such as minestrone or bean & tomato) just too sour.