A sloe day

[Suffolkrafter]

Following on from some recent enjoyable discussions on fruit on the forum, I thought I'd experiment, research and figure out what's going on with sloes and how they can be used. All on the name of science and foraging knowledge.

I've never given it too much thought until now, but there are two separate issues with sloes; firstly, the sweetness or amount of glucose (easily remedied by adding sugar), and secondly the astringency. The two are completely unrelated. From what I've read, astringency is caused by compounds called polyphenols. These precipitate proteins in the saliva - a similar affect to egg white being cooked, and this is what makes your face turn inside out. However there are enzymes present in the fruit which will break down the polyphenols, but these are confined to cellular structures and so don't get access to the polyphenols.

Experiment 1:
Fresh sloes tasted: extremely astringent and unpalatable.
I boiled the same fresh sloes for half an hour with equal weight of sugar, as though making a jam or jelly.
Result - sickly sweet syrup, followed by the same degree of astringency. Completely unpalletable. Cooking doubtless destroys any enzymes which might have degraded the polyphenols. Literature suggests that heat does not break down polyphenols, as I have discovered.

Experiment 2:
Fresh sloes tasted, extremely astringent and unpalatable.
Same sloes frozen overnight and tasted following morning: very little hint of astringency.
Left at room temperature for a few hours, occasional mushing with a spoon; now tastes like a bland plum. I'd consider them edible as they are now.
Freezing presumably breaks down the cells allowing breakdown of polyphenols, in much the same way as starches are converted to glucose following freezing of fruit.

I'm quite pleased with that. Off to make a jam now.

 

[punkrockcaveman]

Absolutely brilliant thank you for sharing!

I was going to attempt a fruit leather with haws and sloes, but I was really worried about the astringency, but I'm happy to give it a go now

 

[Suffolkrafter]

I'd say it's well worth trying. I read one food industry research paper on some other kind of fruit (can't remember which), in which they left the fruit for several days to remove astringency. But then it was a balance between that and fungal infection.
If you do try it and find it is still astringent please reply, as I've not repeated this and there's always the chance I got lucky with a particular batch of sloes.

 

[punkrockcaveman]

Very true, it could well be dependent on how ripe the fruit is before being frozen perhaps. Either way I've got a bunch of them in the freezer begging not to be drowned in gin!

 

[Tengu]

My Aunty was eating them raw. she said they were very sharp and astringent.

(are we surprised?)

Neolithic man ate them, didnt they?

 

[Toddy]

I suspect they might have waited until they bletted though.

 

[Tengu]

Oh, you mean they are that kind of fruit?

I will say Aunty is Finnish; I dont know the history of eating sloes in Finland

 

[Robson Valley]

Freezing slowly as happens in any kitchen situation allows for the formation of ice crystals in the cells. These stab holes in all sorts of cell membranes, releasing everything. What I'm reading in the OP report is that the enzymes are not damaged by freezing. (The enzyme polyphenol oxidase comes to mind.) If anything, this is a very convenient and rapid way to render the sloes edible.