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reverse spherification

post #1 of 3
Thread Starter 
I am trying reverse spherification for the first time. I cannot seem to get it to work.

The recipe I am using is :

450ml of water to 2g of sodium alginate.
1kg of frozen raspberries (defrosted) with 100g white castor sugar to 5g of calcium lactate.

I first make the alginate bath and let it settle for 24 hours.
Then I make a coulis with the raspberries and sugar.
I pass the raspberry coulis.
Add the calcium lactate and blend again.
Then I drop the raspberry mix into the alginate bath and no spherification happens at all?

I am using Evian water (because it is low in calcium)

Can anyone shine a light on this problem? I have read many forums and watched videos on YouTube but nothing is helping!

Many thanx. Dan
post #2 of 3

Sodium Alginate forms weaker bonds (gel) in high acid foods - eventually it won't gel at all if the ph gets low enough.

Raspberries are quite low ph ... here is a sheet with common food stuff and PH levels.  



Raspberries are also fairly low in calcium and that which is present is likely bound up in pectin (not available)

Gere us a sheet with common calcium levels in food.   It doesn't take into account availability though - but it is better than a guess.





In short you're going to need to use a touch more sodium alginate in the water bath (and maybe even use a gelling agent more suited to lower ph levels)  Most preparations I've read are 2.5g to 500g water ratio (0.005) your ratio is (0.004) not a lot but maybe enough when taken into account with all the other variables.


You will also have to use way more calcium lactate.    

A common ratio for acidic foods is 0.02  yours  is 0.005

I would start at 0.015 and work upwards.


For your recipe this would be starting at around 15g per 1000g and working up to 20g per 1000g of coulis.


Once you hit 0.02 ratio your likely going to find better results by adding xanthum gum rather than increasing calcium lactate even more.

I'd start with 1g per 1000g  (ensure your hydrate the xanthum gum very well)


Hope this helps.


Also what size are you trying to achieve?  sometimes the larger ones require more alginate to set faster than they break up when transfering to the bath.



"Plus, this method makes you look like a complete lunatic. If you care about that sort of thing".  - Dave Arnold





"Plus, this method makes you look like a complete lunatic. If you care about that sort of thing".  - Dave Arnold


post #3 of 3
Thread Starter 
Thankyou, I look forward to trying that out later. I would really like to use raspberries, they will go better with the dish I have in mind. Many thanx.
I will let you know my results
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