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Súrsaðir hrútspungar are ram testicles that are boiled, cooled and kept for three to six months in whey that lactic bacteria have soured to about pH 3.6–3.8. The acid of the whey preserves the cooked meat. They are part of þorramatur, the food served in midwinter at the Þorri feast.
Fully documentedMeat3 months – 6 months
Recipe
Amounts from a sourceProportion of whey to food from a Matís meat specialist's account; there is no fixed recipe.
Soured whey (skyrmysa)at least 2 parts whey to 1 part food
Soured with lactic bacteria, for example from sour skyr[visindavefur2023]
Starter
backslop (lactic bacteria from sour skyr kept going in the whey)
Total time across the recorded steps: 3 months – 6 months
Start
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What changes:The ram testicles are boiled through
Step 1 of 4
Boil the testicles
Time
Not documented
Temperature
at least 75 °C
Reported
Salt
None given
Acidity
Not documented
Which microbes the steps name, step by step
Lactic acid bacteria
Flavour
Not documented
Texture
Not documented
Colour
Not documented
Microbes at work in this step
Not documented for this step.
Method
Measured measured in a studySet fixed by a specification or tested recipeReported one source reports itTypical a general value, not sourced for this fermentUnconfirmed not yet checked against a source
At a glance
Súrsaðir hrútspungar are ram testicles that are boiled, cooled and kept for three to six months in whey that lactic bacteria have soured to about pH 3.6–3.8. The acid of the whey preserves the cooked meat. They are part of þorramatur, the food served in midwinter at the Þorri feast. Made in 4 steps over 3 months – 6 months. The longest step, sour for months, takes 3–6 months (Umhverfisstofnun 2005). Lactic acid bacteria in the whey, carried over from sour skyr; they turn milk sugar into lactic acid does most of the fermenting.
The meat is cooked first and then preserved by the acid of soured whey, a lactic ferment of milk, instead of being salted. The meat itself is pickled rather than fermented.
Other súrmaturLundabaggar, sviðasulta, blood and liver sausage and whale are soured in the same way; the same survey sampled them.
Safety
The Environment Agency of Iceland's 2004 survey states that pathogens cannot grow once the food reaches pH 4–4.5, and that the whey should not rise much above pH 4.0; a Matís specialist says more cautiously that going below pH 4.5 greatly reduces the growth of unwanted bacteria. In that survey one sample of hrútspungar failed with inactive lactic bacteria and too high a pH. In the 2007–2008 survey of 70 sour foods (17 of them hrútspungar), 5 had inactive lactic bacteria, which may point to acetic acid added to the whey, and 17 had a pH above 4.5, which can shorten how long the food keeps. A Matís specialist advises boiling to a 75 °C core, cooling below 4 °C before souring and keeping the tub at 5–7 °C.
Hazards the sources name: Gram-negative bacteria (one of 11 samples failed, with inactive lactic bacteria, many yeasts and too high a pH).
A Matís meat specialist writes that souring meat in whey developed in Iceland because salt was scarce; each farm kept a souring tub topped up with sour skyr. A 1958 newspaper report, cited in the 2004 survey, says the restaurant Naustið began serving þorramatur in the old style.