Wednesday, July 20, 2011

Steak Tartare


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.

Sunday, July 17, 2011

Sunscreens, SPF 50


Much excitement in Australia this week with the granting of permission to sell SPF 50 sunscreens.

Got to be 66% better than all those SPF 30 ones, mustn't they?

Well, hold you horses. Could it just be marketing hype?

To get the SPF factor, you divide 100 by 100 minus the percent of the UV radiation blocked.

So if a sunscreen blocks 90% of the UV light, its SPF is 100/(100-90) = SPF 10.

95% = SPF 20

97% = SPF 30+

98% = SPF 50.

So paying the extra money for an SPF 50 sunscreen will increase your protection by just 1%.

If (IF!) it is re-applied regularly and applied at the same thickness as is used in the test (0.1mm).

T-shirts and a hat have a higher SPF factor.