5 replies to this topic

[mind over matter]

Kinilaw means to cook in vinegar, no heat involved. But soaking fish or some other seafood in a strong vinegar solution turns the meat opaque and gives it a texture of having been cooked. It is one of the most famous dishes in the Philippines.

It will be interesting to see what Food Safety experts have to say on this?

[GMO]

Not enough knowledge microbiologically but I do know that this is common as a traditional recipe; e.g. rollmops (pickled herrings) in Britain and other western European countries, Gravadlax (pickled salmon which is salted and fermented presumably forming acid) in Northern Europe and Ceviche (fish in lime juice) in South America. Although I am generally wary of saying "well we've been doing it for years", the fact this is so widespread as a technique suggests there is something in it but I suspect freshness, gutting technique, storage temperature, pH and salt content are key. My gut feel is that the acidity will kill some bacteria and limit the growth of others and there may be a important hurdle effect by combining this with salt and possibly some traditional herbs or spices so it would be important to treat it carefully.

[Dr Ajay Shah]

Totally agree with the comments made by GMO. Pathogens do not grow in acidic environment. But there can be additional factors such as salt concentration, tempreture that can help the preservation process better.

[mind over matter]

Although I am generally wary of saying "well we've been doing it for years", the fact this is so widespread as a technique suggests there is something in it but I suspect freshness, gutting technique, storage temperature, pH and salt content are key. My gut feel is that the acidity will kill some bacteria and limit the growth of others and there may be a important hurdle effect by combining this with salt and possibly some traditional herbs or spices so it would be important to treat it carefully.

I’m not sure if they follow specific storage temperature, and if so, what it is. The raw fish is marinated in vinegar or Calamansi juice along with garlic, onions, ginger, tomato and various peppers.

[YFoodSafety]

Dear all
All suggestions were appreciated, but as GMO wrote "Not enough microbiological knowledge" you have to validate the the current product (vinegar-socked fish) safety and then we have to select any needed corrective action.
Regards,
Youssef

[Jocelyn Hu]

The "cooking" in vinegar you are refering to is the protein being denatured by low pH which is a similar effect to heat denaturing protein. The difference is that different bacteria will be affected by low pH vs heat treatment.

Vinegar (low pH) is one of the hurdles to microbial growth. This will hinder some bacteria but other safe handling methods are still required such as washing the fish in clean suitable water and of course starting off with suitable quality raw material to ensure food safety.

Other typical hurdles are removing available water (could be via adding large quantities of sugar or salt in the solution), removing oxygen hinders growth of anaerobes if the fish is stored in liquid or low temperature storage (if the product is stored in a fridge or freezer temperature range), etc. The more hurdles there are, the harder is is for bacteria to survive.

So from the limited information, it's difficult to guarantee that "cooking" with vinegar is sufficient for food safety, but it's 1 step in making it more difficult for some bacteria to survive.