Not ducking the question.

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Celia of Fig Jam & Lime Cordial, asks

"I've been making confit duck, and keep it for a short time in the fridge.

1. As instructed, I've been reheating the used duck fat to clarify it and then storing it in the freezer to be reused next time - is this a safe practice, and how many times can the fat be reheated and reused like this, please?

2. Secondly, confit duck (a traditional food) has been stored for generations by the French on the pantry shelf, with some instructions going so far as to say "don't worry if the bones not covered in fat go a bit green". I don't do that, I keep it in the fridge, but wondered whether it was actually safe to store meat like this unrefrigerated?

Question 1. It is a matter of taste. Over time there is a likelihood that the fat will start breaking down but that in itself is not harmful. The issue is whether the taste is affected. My Granny had a 'dripping pan' that used to hold fat that was returned time and time again to the weekend roast, with no ill-effect. Animal fats are generally too saturated to have oxidative rancidity and hydrolytic rancidity (the splitting of the fatty acids from the glycerol backbone of the fat) often cannot be tasted. A text book I read once famously said that a fat was rancid if it tasted rancid and that all other tests were, at best, just corroborating evidence.

The splitting of the triglyceride happens during digestion so it is no a health hazard as such.

So, in short: as long as the fat still tastes ok, it is fine.

Question 2. The fat layer is supposed to keep the meat protected. Despite what advertisers of disinfectants and such like would have you believe, bacteria do not spontaneously appear for no good reason. This is a habit solely retained for the start of a new Universe. If your duck is cooked, it will be sterile and the thick layer of fat will keep it sterile.

Has done so safely for many many years.

Green is more problematic but not necessarily harmful. The pigments in blood - haemoglobin and myoglobin, will oxidise and go funny colours, mostly green, grey and brown, with exposure to the air. Unsightly but not harmful. The surface of the chicken paté I make discolours quite quickly but is not harmful.

More important is to make sure that the exposed bones and such like are not handled as they do not have the layer of protective fat and will possibly give bacteria a toe-hold.
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Steak Tartare

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Celia, of Fig Jam & Lime Cordial, asked "Does the traditional food rule apply to dishes like steak tartare?"

Yes, is the short answer.

Steak Tartare is a traditional food.

Despite the rantings of Professor A. C. Grayling, philosopher and vegetarian irrationalist, meat is not full of bacteria. (See here) Once you cut it, though, bacteria is introduced and the life of the meat starts being reduced.

A number of things need to be remembered:

1. The amount of bacteria that you introduce in chopping the meat is quite small. Especially if you take care to use clean knife.
2. Bacteria, at room temperature, will double in numbers every 20min, so what starts out as a low level can rise very quickly.
3. Most spoilage bacteria is just that, spoilage bacteria. Pathogens, such as E-coli or Salmonella, are less prevalent and less likely to be introduced in the chopping of the meat.
4. The concept of an 'infectious dose'. Everyday we are ingesting low levels of bacteria, including pathogens, with no ill effect. There is a certain level that is necessary to induce illness.

The long and short of it is that Steak Tartare must be made fresh and eaten fresh.

That is the traditional way to do it.

And it is quite safe.
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Smells dead, must be dead.

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Chairman Bill asked: "How about trassi? I've heard some hideous stories about it, although I've eaten plenty of it in my time (both as a Dutchman and when in Indonesia/Malaysia)"

This is an amazing fermented dried shrimp paste that smells awful but tastes wonderful.

The big thing is that this is a traditional food; a pretty reliable sign of a good track record for safety.

And the traditional way of cooking it is to stir-fry in a very hot wok. This will kill any bacteria that may be in it. Deviate from traditional cooking processes at your peril.

It must also be remembered that it is usually a dried product and so lacks the available water needed for bacterial growth.
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Revisiting Alfalfa Sprouts

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Pythagorian asked: I read your warning about alfalfa sprouts and wonder how and what bleaching methods you recommend. Also I have read a claim that there has never been a case of sprout contamination traced to certified organic sprouts. Do you know if this is true or false?

The common commercial process is shock chlorination of the seeds and chlorination of the water.

The organic claim will be false. The main issue is you have a protein-rich food source that you are keeping wet and warm for several days. Any bacteria present will thrive. This has nothing to do with the organic status of the food, bacteria is naturally present in the environment. In some ways organic produce may have more bacteria. This is not a bad thing, just a consequence of things growing in the open.

Chlorination will kill the bacteria. Other processes might too. My observation is that there is not much margin for error. Warm and wet, bacteria will double in numbers every 20 minutes and most sprouts are eaten uncooked.

The Chinese eat lots of sprouts, without problems, but they stir-fry them and this kills the pathogens.
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Hot and cold on Cayenne

medavinci asks "Is it true cayenne pepper can lower blood pressure and open arteries? Can you just sprinkle it on your food or should it be cooked like curry to avoid salmonella? "

OK, a two part question:

Part 1. Is it true cayenne pepper can lower blood pressure and open arteries?

Maybe. Certainly many foods have physiological effects. A peek on the internet finds a squillion and one sites selling the benefits of cayenne pepper (as well as selling the cayenne pepper) but I couldn't find any mainstream sites, just the herbal fringe. This always makes me suspicious. But I have no reason to doubt that it MAY affect blood pressure. In either direction.

Opening arteries is a little more serious. Certainly people can get flushed in the face after eating peppers, chillies and such like. Is the the same as 'opening arteries'? Maybe. Is it desirable to look flushed? Possibly not. Is it the same as unclogging arteries from too many fries over a lifetime? No.

Maybe it works, maybe it doesn't. By the time you find out, the purveyors of fine herbal remedies will be telling you to eat, drink, roll in something else. But, if you feel that it is good for you, then it is. Isn't it?

Do be aware of the possible risks associated with cancers, especially mouth cancers, from excessive and prolonged consumption of irritants like chilli and pepper.

A rule of thumb that I always have with herbal remedies (like the one in this morning's paper that said magnolia flower tea cures hayfever) is a very simple question: if this cure, cayenne pepper, is so good and so effective, why are the major pharmaceutical companies not growing broad-acres of the stuff? These guys are pretty keen to corner the consumer dollar and never slow to see an opportunity.

Could it be that the efficacy of cayenne hasn't been proved to the level of certainty required by good science and the auditors of the Therapeutic Goods Act?

Remember: Alternative medicine that works is called... medicine.

Part 2: Can you just sprinkle it on your food or should it be cooked like curry to avoid salmonella?

If you are consuming it immediately it will be safe to take 'raw' as it were. If you are putting it into something warm, moist and nutritious and not planning to eat it for a few hours, cook it first.

French Dressing

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French dressing is one of the classic salad dressings.

Mine is typically made 'by eye' rather than recipe but, in essence, is as follows:

50ml cider vinegar
200ml olive oil
Crushed garlic, to taste
Qtr teasp mustard powder
Salt & Pepper.

So, for a product that is about 80% oil, how do the Krafts of this world explain the culinary obscenity that is "Fat Free French Dressing"?

Sure, it is a 'salad dressing' but why not call it what it is 'Sweetened, jellied vinegar"?

It's not French. And it's not right.


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Curry Powder

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Sara asked about curry powder.

There is absolutely nothing wrong with curry powder. It has been safely used for many centuries, following time honoured and well proven practices.

But what if those practices are not followed?

First, let's look at what curry powder is. It is the ground mixture of spices, seeds of a variety of plants. Seeds that have been exposed to the environment. There is nothing abnormal in that but, because of their origin, the seeds that go into curry powder will bring with them a variety of organisms from the environment. Notably Salmonella.

Now, how is curry traditionally prepared? You heat oil in a pan and cook the powder in this oil. Ostensibly to 'bring out the flavour' but, by a happy coincidence, it also sterilises the powder. You then add meat, vegetables, whatever and continue with making your curry.

What happens if you deviate from this long proven, survival enhancing, cooking practice? What if you are a new age cook and make a curried pasta salad where you just mix the warm (!) pasta, mayonnaise, vegetables, cream and curry powder and stir? Nothing much if you eat it straight away. But bacteria will double roughly every 20min at room temperature; what if you make your salad early and leave it for a few hours before eating? Not a good idea - the salad is warm, moist and protein rich - happy times for the bacteria.

Because of the risk, spices are one of the few things that are permitted to be irradiated to sterilise them. But this does not teach people safe handling practices for a potentially dangerous food. People will just be ignorant of the dangers and at risk from spices that are not irradiated.
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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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