Yoghurt

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Indi wanted me to "write about yoghurt". This is a broad sort of request! I will deal with it with a heap of observations and if there is anything people want to expand on we can deal with that later.

Yoghurt is a fermented milk product where the bacteria convert the lactose in the milk to lactic acid. The lactic acid gives the yoghurt the sour taste and ‘sets’ the milk by coagulating the proteins. The acidity also helps prevent other, possibly harmful, bacteria growing.

As the lactose in the milk is largely converted to lactic acid, yoghurt is usually well tolerated by people who are lactose intolerant and is easy to digest generally.

I am not a big fan of the fruit yoghurts, usually too sweet for me, but there is nothing wrong with them.

I like Jalna yoghurts but, for the one pictured above, take philosophical exception to the idea that (1) the product is fat free, it isn’t, (2) that fat free milk is in anyway natural, it isn’t. Not from the cows I know, anyway. Sadly, I don’t think they make full fat plain set yoghurt any more but their Swiss Custard Yoghurt is far too nice.

That hard white stuff you find on the top of ‘health’ bars might be called yoghurt but it isn’t. It is yoghurt flavoured fat, mostly saturated fat.

Probiotic yoghurt drinks probably do no harm (though they are twice as sweet as Coca Cola) but it is a open question as to whether they do any good. While the bacteria used will pass through the stomach into the intestines, they are not self sustaining and disappear from the system in a few days if not constantly replenished. I do not see their value and take the view that the flora that has thrived in the intestines over the eons are probably the best ones to have there.

Greek yoghurt has a higher fat level (10% cf normal yoghurt of 3%) and hence is more creamy.
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Lady Fi's Onions and a bit on gold, for good measure.

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Lady Fi asks: Have you read my post about onions?
Why not tell us more about the tearful reactions they can trigger in lots of us?

Also - what's the deal about alchemy turning stuff into gold? How did it start? Why did people try? And is it really impossible?

Onions make you cry because, when you cut them, you release Propanethial S-oxide, a volaile compound that reacts with the moist surface of your eye to form sulphuric acid. Your eyes then water in response to this irritation.

Interestingly, onions do not contain propanethial S-oxide and it is thought that onions produce this tear inducing compound to protect the plant from herbivores. It is the product of a series of chemical reactions that occur once the onion has been damaged. Cells are broken open as the onion is cut and this releases the enzyme alliinase and water, which react with S-1-propenyl-L-cysteine sulfoxide forming a mixture of products including propanethial S-oxide.

Various suggestions are about to stop this process - cutting onions under water, chilling onions to reduce the volatility of the compound, heating the onion to kill the enzymes that create the compound, or what I sometimes do if the stove is free, cutting the onions under the exhaust fan on the stove.

And gold?

The alchemists have dreamed of turning lead into gold but, alas, had to fall back on other retirement schemes. Modern day nuclear physics has successfully transmuted lead into gold, but the expense far exceeds any gain. Ironically, it transpired that, under true nuclear transmutation, it is far easier to turn gold into lead than the reverse reaction, which was the one the alchemists had ardently pursued.


Reference:
http://www.chm.bris.ac.uk/motm/pso/psoc.htm
http://en.wikipedia.org/wiki/Nuclear_transmutation

The most dangerous food in the world!

This is a repost from A Curate's Egg, but it is topical (re The Fat Duck post) and really belongs here .

In my previous incarnation as a food chemist I was often asked ''What food shouldn't we eat?"
I'm not sure what people expected me to say.

Butter, maybe.

In the incarnation prior to that one, I worked at the Coroner's Court doing post-mortem drug analyses. No one ever asked me what drugs they shouldn't take.

However, there I am, Food Chemist, at a dinner party or a BBQ and after the obligatory "What do you do for a living?" question I get the "Oh, really? What food shouldn't we eat?" question. Always tricky if you don't know what is on the menu. But few people are ready for my reply.

Alfalfa sprouts.

Yes, those clean, green, biodynamically pumped shoots are one of the most treacherous foods on the menu.

"Surely not! You're joking, right?"

Wrong.

Think about it. Seeds of any sort are open to the environment. They will have bacteria on them. So what do you do with them? You soak them in water and leave them somewhere warm for three days. Water, warmth, and the seed, a good souce of protein. Bacteria heaven.

"But sprouts have been eaten for centuries." they protest.

"Cooked" I respond. Eating sprouts raw is a recent 'healthy' practice.

Cooking sprouts will kill any bacteria.

That doesn't mean that raw sprouts are bad, just that they are high risk. There is no safety net.
You can reduce the risks by using boiled or chlorinated water and changing the water frequently.

"Now, would you like my thoughts on curry powder? Or margarine?"

"Ah ... that's very kind of you but I can see an actuary over there that I have been dying to talk to ... "

The Fat Duck & Quantum Chemistry

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Chairman Bill asked: "Would you care to comment on The Fat Duck interpretation of quantum chemistry."

He expanded later, with: The Fat Duck is a 3 star Michelin restaurant in the UK run by Heston Blumenthal, who is renowned for using the principles of chemistry in his menu design. Unfortunately he had to close down for a couple of weeks due to an outbreak of vomiting and diarrhoea, although the health inspectors gave his place the all clear.

I have met up with a Spanish equivalent, el Bulli. My son, Richard, gave me a megabook on a day in the life of el Bulli for Christmas.

I find it a cute idea but I can't afford to go to the restaurant and I can't afford the equipment needed to do a lot of it at home. They do things like use liquid nitrogen to freeze things. Fascinating but out of the reach of the home cook. There must be a few things I can do so that I can impress Richard; I have a dehydrator for example. (Watch this space.)

What really caught my attention was the comment by Chairman Bill that the UK restaurant had been closed due to food poisoning. It may well have been coincidental and nothing to do with the restaurant (that is often the case) but it does play to one of my food safety themes: be very wary of food prepared in non-traditional ways.

I will write more another day on the subject but most food is safe because we prepare it the way countless previous generations have prepared it. And survived. The problem is most people don't understand why this is the case and, in ignorance, try shortcuts.

With quite dire results, sometimes.
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Grey Water

Anonymous said:

Not sure if this is up your alley, Lee, but I've heard you shouldn't put grey water (say water from the shower that might have a bit of soap and dead skin in it) onto plants that you intend to harvest for food later, like herbs or pumpkins. If this is your sort of area, what's the deal?

The issue is that the water has more than soap and skin. It will have faecal matter, no matter how well you have wiped your bum. Blunt but true. The same applies to laundry water that has been used to was undies etc.

Related to that is the issue that this bacteria will multiply if people store the water for any length of time. The resultant soup is smelly, slimey and a hazard to children.

The counter story, and there is always a counter story, is that the plants in the vegetable garden are routinely exposed to salmonella, ecoli and other such nasties from the wind, birds and insects. If normal hygienic practices are followed, there shouldn't be a problem.

Interspersed with all this bacterial culture is the litigious culture that abounds at present; no politician is going to say 'use your grey water on your vegetables' and then face the consequences of a potential food poisoning. Far safer, politically, to say don't use it.

Me? I used grey water on my raspberries; they are not in fruit until October so no problem and they survived the summer better than they ever have. A bit sunburnt but you can't help that with watering. I also used it on some rhubarb, knowing it would be comprehensively cooked and never eaten raw. I used grey water extensively around the main garden and on all the fruit trees.

Ideally, if you need to use grey water on vegetables, you should contour your garden beds so that you can water them by running the water down a ditch between rows so that it gets directly into the soil without touching the vegetables themselves.
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Chemists and Food

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Chairman Bill asks: "My partner is a biochemist and maintains that if you're a half decent chemist, then you understand food and should be a natural cook (she is the best cook I've ever come across)." and "If chemistry was a compulsory subject at school, would people be more likely to tackle cooking?"

Well, my interests include chemistry and art. I take the view that cooking is where the two overlap. To my mind, art is the more important of the two - everything hinges on presentation.

To that end I only use white plates.
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Food Additives

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Courtney asked for my “thoughts on food additives in our diet. Specifically, what is your scientific and always logical take on artificial colors/dyes and preservatives in the food and their impact on behavior?”

The answer varies with the additive unfortunately.

Additives fall into a variety of categories but the first major split is into colours and others. Courtney specifically refers to colours, antioxidants and artificial sweeteners.

Colours
Colours are really for cosmetic purposes only and serve no useful purpose to the consumer. They can make pallid and insipid looking foods look more attractive (eg: adding yellow to pasta, cakes or ice-cream makes them look a richer colour, as if they have eggs in them.).

There is no doubt that colours are not necessary. They are an aesthetic additive.

Antioxidants (BHA, BHT, TBHQ)
These additives are generally added to oils and oil containing products to delay the onset of rancidity and extend shelf life; to this end they serve a useful purpose. As well as flavour deterioration, the by-products of rancidity, peroxides and acids, are considered to be harmful. This is where antioxidants have a problem: they are an additive but, unlike colours, they do serve a functional purpose. And this is where the regulators need to walk a fine line: the health risks of the additive vs the health risks of not using the additive.

Artificial Sweeteners
These are more insidious additives, in my mind. There is no denying that obesity is a growing problem (!) but is replacing sugar with something sweet but without calories the answer? It is not training people to enjoy unsweetened food but rather maintaining a need for a certain level of sweetness. Also people do false bargains with the devil when they say “I had a diet cola so I can have a chocolate bar”.

Preservatives
This is a fairly broad group of additives. Sulphur Dioxide is used very widely for different reasons. With the likes of sausages, they will not last a day raw without preservative (because you are seeding the minced raw meat with bacteria filled other components – flours, spices etc.). Dried fruit, such as apricots, go dark brown without preservative but will survive quite well without it IF they are properly dried. If they are kept still moist, (could they be being sold by weight?) yeasts can grow in them. Many soft drinks contain the preservative Benzoic Acid to prevent the growth of bacteria during storage. Again there is the issue of the health risks of using the additive vs the health risks of not using the additive.

At one level, it seems logical that manufacturers will not use additives unless they feel that they are needed in their food. Why incur an unnecessary cost? But reality is that the cost of the additive is not great and the ability of the manufacturers to control the amounts added is variable. Ultimately, as an insurance, they often use too muych rather than too little.

That was the easy bit.

“Are these additives harmful?” is a harder question. At some point everything is harmful. One grain of sand will bounce off you shoulder, a truck full dumped on you will smother you. Do additives impact on children’s behaviour? Quite possibly. There is the issue of causality though. This is something that I will probably come back to time and time again in this blog. Do colours make your child hyperactive? Or is it the sugars that are often present with the colours? Or something else altogether?

Ultimately it is something that must be decided on a case by case basis. If they affect your child, all the assurances of the ‘experts’ amount to nothing; they affect your child.
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