Stuck Fermentation

[morlando27]

I started brewing a Mangrove Jack's pear cider kit January 7th. The initial SG reading was 1.051. One week later, it was 1.025, where it has been stuck ever since. I have tried raising the temperature using a heating mat, adding yeast energizer, and pitching a new packet of rehydrated yeast but nothing has made a difference in the SG readings. Is there anything else I can do?

 

[DBhomebrew]

How do you measure gravity?

 

[morlando27]

Using a refractometer. I've used it before but guess I forgot that you need to calculate the final gravity to account for alcohol rather than taking a direct reading. Oops!

 

[dmtaylor]

Welcome.

 

[Chalkyt]

A hydrometer would be better, however if you don't have one, taste will give you a good idea. SG of 1.025 (in fact anything over 1.015) will taste quite sweet, whereas fully fermented there should be little or no sweetness. As a guide, SG 1.020 is about 40 grams of sugar per litre which is similar to 2 teaspoons of sugar in half a pint (8 oz glass) of cider or cup of coffee.

 

[DBhomebrew]

If you don't have a hydrometer, better use taste over a refractometer?!

 

[Zambezi Special]

Use both
I've just put those figures in a handy little app called brewking (you can use brewers friend, brew father etc) and actual FG is around 1.010 with an apparent attenuation of 81% which sounds pretty much on target for a cider kit

 

[morlando27]

It tastes quite sweet to me BUT the directions have you add an artificial sweetener at the same time as pitching the yeast so I think a lot of the sweetness can be attributed to that.

 

[Chalkyt]

I don't know what effect the sweetener will have on the density or if you need a correction factor (to adjust the SG or Brix if the hydrometer floats differently or light refracts differently) so probably this time around if it tastes good and hasn't been bubbling for a while you can probably assume that it is done. By any chance did you get a refractometer reading of the juice and the juice plus sweetener? Was there a difference?

I understand that to use a refractometer accurately for monitoring SG, you need to have some idea of the corrrection factor (I have no idea what this is for cider... maybe someone has done the brix vs hydrometer SG exercise and can tell us). I have simply used a factor of 1 just to get an idea of where my cider is at after 1 week, two weeks etc just pipetting a drop or two rather than waste the must or risk contamination. But, I use a hydrometer at the very end when taste suggests that it is done and ready for priming in order to know exactly what the SG is in order to dose properly. If you are simply heading for a dry non-carbonated cider the exact bottling SG probably doesn't matter too much as long as it is close to 1.000 (or at least less than 1.003 or so).

 

[morlando27]

No, I didn't think to take a reading before adding the artificial sweetener. I have another flavor kit to try when I'm done with this one so I will take before/after readings next time to see if the sweetener alters the refractometer reading. Since the sweetener doesn't ferment, as long as I took the initial reading after adding it, it would be present in both readings so I believe the relative change would still be valid even if it does alter the reading, right?

After realizing my error about failing to adjust the final gravity reading and subsequently consulting several different online calculators, I'm feeling much better about proceeding with bottling. Thanks for the help!

 

[Chalkyt]

Yes, I would expect the differential or offset to be the same at each reading. As far as I know, the general practice is to add sweetener at the end of fermentation. Adding it at the beginning seems to be a little unusual although I can understand if it is just a matter of following a formula, recipe or kit instructions without taking any measurements. In that case it probably shouldn't matter when you add it.

 

[Raptor99]

I understand that to use a refractometer accurately for monitoring SG, you need to have some idea of the corrrection factor (I have no idea what this is for cider... maybe someone has done the brix vs hydrometer SG exercise and can tell us).

If you have the original and current Brix, use this: Homebrew Refractometer Calculator

 

[bracconiere]

refrac readings come in handy to if you ever forget to take a OG reading....

 

[Chalkyt]

Hey, that is pretty cool. I generally only use the refractometer to check apples and rough progress of fermentation. Where is it from?

 

[bracconiere]

Hey, that is pretty cool. I generally only use the refractometer to check apples and rough progress of fermentation. Where is it from?

well that's a snip from beersmith2....but here's an online calc that does the same from NB, and finding this out is the only reason i have a refrac. I wish i knew this trick when i was trying to make sake....with the slow aditions of rice and koji, i never could tell if any alcohol was being made!


https://www.northernbrewer.com/pages/refractometer-calculator

edit: new link same as the old one!

but with pictures!

just thought i'd include another HBT tip about refracs....

 

[morlando27]

Yes, I would expect the differential or offset to be the same at each reading. As far as I know, the general practice is to add sweetener at the end of fermentation. Adding it at the beginning seems to be a little unusual although I can understand if it is just a matter of following a formula, recipe or kit instructions without taking any measurements. In that case it probably shouldn't matter when you add it.

I thought it was a little strange myself but the directions have you add the "sweetener sachet" along with the yeast, then add "cider essence" (flavoring) at the end of fermentation. Maybe there are some fermentable ingredients in the sweetener as well?