Adding plum juice after initial fermentation

[Mad-fish1960]

Hi all, we have successfully made a few years of apple cider with our best results obtained by adding lactose for the initial fermentation. Last year we crushed a few plums with our apples to see if we could introduce some additional flavour, although the result was pleasant, no plum flavour was detected.
This year we would like to add some plum juice after the first ferment, this is where I need help.
Question 1 if I add say 1 litre of frozen plum juice to 4 litres of cider, this will obviously raise the SG and if then bottled will that lead to exploding bottles on the second ferment or should I just leave out the teaspoon of sugar I normally add on bottling, we like a sparkling cider.
Question 2 Should I just let the plum juice ferment out, and then bottle or will I again lose flavour.
Question 3 What is a SG that is safe to bottle.
Any help with this process of adding other juices , when and how would be a huge help, thanks in advance.

 

[madscientist451]

You aren't going to get plum juice flavor if you want to let it ferment. If plum flavored cider is you goal, freeze your plum juice in small plastic containers and bottle your cider. When you want to have the plum flavor, thaw out some juice and make a "cider cocktail" by putting a shot of plum juice in your glass of cider. Add more or less to taste.

 

[CKuhns]

Edited, did not mean to post or quote. Sorry.

 

[Chalkyt]

The short (or possibly long) answer to your questions is to go back to the basics.

Plum juice has about 130g of sugar per litre which is about the same as apple juice, i.e. you would expect the SG to be around 1.050. I guess that crushed plums would be about the same. I have done something similar to you by adding about 10% frozen and mashed cherries into a secondary fermentation of apple and pear juice for an apple/cherrry cider. It started as an experiment to see if the high levels of non-fermentable sorbitol in the pears left some residual sweetness.

I used SO4 yeast which often finishes in the range 1.002 to 1.004 leaving some unfermented sugar and hence a touch of sweetness. So I bottled at 1.005 and ended up with a lightly carbonated, slightly sweet cider which certainly displayed cherry notes and wonderful colour. In fact it scored 48/50 and won the local rural show a few years ago... success by accident!!!!

However, this pointed me towards understanding the basics of what happened. The following explanation should answer your Questions 1 & 2. It is a bit scientifically rough but bear with it, here goes...

Apple juice (and lets assume, plum juice) is typically 80% water and 20% flavour compounds of which 80% is sugar. If you ferment all of the sugar out, you are left with water, acid, tannins and other stuff. i.e. the main item that makes it taste nice (sugar) is all gone.

So, unless you are looking for a dry and tart apple/plum cider you will probably need to retain some unfermented sugar or add a non-fermentable sweetener like stevia, xylitol etc. To retain some sugar, the fermentation will need to be stopped by chemicals or by heat pasteurisation to kill the yeast (I use heat pasteurisation but others swear by chemical means... take your pick!)

Even though there are other compounds that affect the density of a cider their influence is relatively small and so SG can be taken as a reasonable proxy for the amount of sugar in a cider (a good website for SG vs g/L of sugar is the Vinolab Calculator... if it comes up in croatian, click the English tab in the top RH corner).

As a rule-of-thumb, medium dry ciders have a FG of about 1.010 (25g of sugar/L), medium sweet about 1.015 (40g of sugar/L), etc. As a guide, 20g/L is about the same as a teaspoon of sugar in a cup of coffee.

These days for a cider with a touch of sweetness I will bottle at around SG1.010 to1.012 and heat pasteurise at 1.006 to 1.008 for a slightly sweet carbonated cider (you can either use the soda bottle squeeze test or a bottle with a pressure gauge to judge this). The SG change of 0.004 will result in about 2 volumes of CO2 which is about what I like. Most commercial beers, soda, etc are carbonated to around 2.5 volumes.

So, you can add your plums and juice after primary fermentation, see what the SG is and work from there to figure out when to bottle etc for the carbonation and sweetness that you want.

For your Question 3, the answer depends on the type of bottle, which can range from used beer bottles to champagne bottles.

Manufacturers usually rate beer bottles bottles at 1.2 to 1.6MPa (i.e around 200psi or more) with champagne bottles at almost twice this.

One volume of CO2 is about 15 psi of pressure in a bottle . So a typical bottle of beer will have about 2.5 volumes of CO2 creating 45 psi of pressure. Some studies have shown that manufacturing batch testing of bottles can allow the occasional below spec rogue bottle to get out into the marketplace, so as many of us use recycled bottles it is prudent to limit pressure to well below the manufacturers' ratings.

Bottling at anything more than SG1.012 and letting it ferment all the way to 1.000 will generate about 90 psi of pressure (based on a 2 SG point change generates 1 volume or 15psi of carbonation in a bottle) . Similarly, pasteurising a bottle with 2.5 volumes of carbonation at 65C will generate pressure in the order of 109psi until it cools down again. I guess it is for individuals to decide how much margin of safety they want.

Sorry I haven't given you YES and NO answers but I hope you managed to read this far and it helps you get your own answers.

Cheers!

 

[J2W2]

I've been thinking about making a plum cider, and I was planning to use 100% plum juice (from concentrate). Is that a good plan, or should I be looking at a mix of apple and plum juice for the base?

Thanks!

 

[Chalkyt]

I am certainly not an expert on this but what you are suggesting just sounds like a fruit wine. Others might have better advice but I have generally just made cider with about 20% fruit (or juice) added to the secondary ferment if I want a "fruit" cider.

 

[J2W2]

I am certainly not an expert on this but what you are suggesting just sounds like a fruit wine. Others might have better advice but I have generally just made cider with about 20% fruit (or juice) added to the secondary ferment if I want a "fruit" cider.

Now that I think about it, I believe you may be correct.

When you say you add 20% fruit or juice to the secondary ferment, do you mean you ferment the apple juice and then add your other juice? And do you allow the addition to ferment out as well, or do you stabilize the apple cider first or shortly after adding the second juice? I want to make sure the plum flavor shines through.

 

[Raptor99]

There is a big difference between a fruit "cider" made with 100% plum juice vs. an apple cider with some added plum juice. Either one could be good, but they would be quite different. True perry (pear cider) is made with 100% pear juice with no apple juice. It would be interesting to try that with some other fruits.

I think that there is a fuzzy line between cider and wine, mostly depending on ABV. If your 100% plum juice with no added sugar produces 6-7% ABV you could call is a plum cider. But if you add sugar and the ABV is above 10%, you could call it plum wine. Call it whatever you want, as long as you enjoy it.

It might be helpful to refer to some plum wine recipes for ideas, even if you are not adding sugar. Let us know how this turns out, because I am thinking of making some fruit ciders.

 

[Chalkyt]

I haven't made "Cherry Cider" for a couple of years, but looking at my notes (it is useful to keep a log of ingredients, SG, etc when you make something new, just in case it works!), the progress went something like...

The primary juice blend was 80% three different type of apples from my trees plus 20% beurre bosch pear. Fermentation was with SO4. At SG1.015 after racking to a secondary carboy, frozen pitted cherries and juice was added and the SG increased to 1.020 so they must have had a fair level of sugar. Fermentation was allowed to continue down to 1.003.

At that point some of the apple juice blend was added to raise the SG to 1.005 and the cider was bottled. There was some residual sweetness probably from both the sorbitol in the pears and unfermented sugar (SG1.005 represents about 12g/L sugar). The idea being that SO4 would continue fermenting and chew up maybe half (or a bit more) of the unfermented sugar and stop somewhere above 1.000 so I would end up with something like 2 volumes of carbonation. If fermentation continued all the way to 1.000, carbonation could have been 2.5 volumes and left no unfermented sugar. In the end it worked out about right but the point is that there is a lot of guesswork and hoping involved.

If you want the plum flavour to shine, I would suggest letting the cider ferment down to somewhere below 1.010 then add plum juice to a sample. Taste and decide if it is what you want. If it is, then extrapolate the quantity to the rest, add priming sugar, bottle and heat pasteurise once you have carbonation. See other posts on the forum re heat pasteurisation. In general terms heating the bottled cider to 65C for ten minutes then letting it cool down will stop fermentation.

if it is too sweet after adding the plum juice, then let fermentation continue, tasting until it is what you want, then prime, bottle and pasteurise. Alternatively if you can relate the taste you want to a particular SG of the combined cider and plum juice sample, then simply bottle at 4 or 5 gravity points above that for carbonation and pasteurise when the carbonation is where you want it (i.e. when the extra 4 or 5 gravity points have been fermented).

If you are nervous about potential bottle bombs you can carbonate using CO2 cylinders or kegging but I haven't gone down those paths.

The main issue you have to consider is that chewing up too much sugar from the plum juice will change the flavour. You might like to look at some of the new Fermentis yeasts. In particular there have been some posts here about TF6 which is intended for fruity types of cider. Attached FYI is a paper from Fermentis about these yeasts.

 

[J2W2]

I haven't made "Cherry Cider" for a couple of years, but looking at my notes (it is useful to keep a log of ingredients, SG, etc when you make something new, just in case it works!), the progress went something like...

The primary juice blend was 80% three different type of apples from my trees plus 20% beurre bosch pear. Fermentation was with SO4. At SG1.015 after racking to a secondary carboy, frozen pitted cherries and juice was added and the SG increased to 1.020 so they must have had a fair level of sugar. Fermentation was allowed to continue down to 1.003.

At that point some of the apple juice blend was added to raise the SG to 1.005 and the cider was bottled. There was some residual sweetness probably from both the sorbitol in the pears and unfermented sugar (SG1.005 represents about 12g/L sugar). The idea being that SO4 would continue fermenting and chew up maybe half (or a bit more) of the unfermented sugar and stop somewhere above 1.000 so I would end up with something like 2 volumes of carbonation. If fermentation continued all the way to 1.000, carbonation could have been 2.5 volumes and left no unfermented sugar. In the end it worked out about right but the point is that there is a lot of guesswork and hoping involved.

If you want the plum flavour to shine, I would suggest letting the cider ferment down to somewhere below 1.010 then add plum juice to a sample. Taste and decide if it is what you want. If it is, then extrapolate the quantity to the rest, add priming sugar, bottle and heat pasteurise once you have carbonation. See other posts on the forum re heat pasteurisation. In general terms heating the bottled cider to 65C for ten minutes then letting it cool down will stop fermentation.

if it is too sweet after adding the plum juice, then let fermentation continue, tasting until it is what you want, then prime, bottle and pasteurise. Alternatively if you can relate the taste you want to a particular SG of the combined cider and plum juice sample, then simply bottle at 4 or 5 gravity points above that for carbonation and pasteurise when the carbonation is where you want it (i.e. when the extra 4 or 5 gravity points have been fermented).

If you are nervous about potential bottle bombs you can carbonate using CO2 cylinders or kegging but I haven't gone down those paths.

The main issue you have to consider is that chewing up too much sugar from the plum juice will change the flavour. You might like to look at some of the new Fermentis yeasts. In particular there have been some posts here about TF6 which is intended for fruity types of cider. Attached FYI is a paper from Fermentis about these yeasts.

Thank you - this is all very helpful.

I was not planning to use a secondary. I have a 12L Speidel fermenter that I thought would work well for the 2.5 gallon batch I was planning to make. Could I add the plum juice to the primary, after the apple juice ferments down, or is a secondary the best way to go for a cider like this?

I was also planning to keg the cider (I have a two-gallon keg), carbonate it, and then bottle from the keg. Once I get the sweetness I'm after, I was going to do a quick cold crash and add some Potassium Sorbate and Potassium Metabisulfite to stabilize it. I did something similar with a hard rootbeer.

I was planning to try Fermentis SafCider AB-1, for a balanced finish, but TF-6 does sound like it could be more of what I'm after.

 

[Chalkyt]

Yep, that all sounds fine. Primary and Secondary fermentations are just concepts with Primary seen as the turbulent start to fermentation where you get lots of CO2 and foam generated, and Secondary being the quieter period when pulp, dead yeast etc settle out and you have a clearer cider which ferments down and matures.

Generally, the notional transition between the two occurs a couple of weeks after fermentation starts, and is typically at about 1.020 -1.030. But, there isn't a "magic number" it is just a way of thinking about the two phases of fermentation.

I only do one gallon batches (actually 5 litres) and rack from Primary to Secondary because I use the approach suggested by Claude Jolicoeur. Fermentation is started in an open but covered container (my bottling bucket) holding about 10% more than my secondary carboy needs. This way I can easily monitor the progress and leave the surface of the cider exposed to O2 which the yeast need initially (the foam and CO2 buildup quickly isolates the fermentation from O2 spoilage). Once the turbulent phase has finished (i.e. the foam settles down) I will rack to fill the secondary under airlock. The extra 10% left in the bottom of the bucket which contains the settled "muck" gets discarded or filtered and kept as a top up in case it is needed.

So there is no reason why you couldn't do it all in your Speidel fermenter with sorbate etc to stabilise it and kegging. I guess that the only caution that I would have is that the timing of adding the plum juice will be crucial in order to get the final sugar level (and hence taste) just right, as discussed in the earlier posts.

If the plum juice is added too early, you might reach the desired flavour profile before much alcohol has been generated (i.e. just a low alcohol apple/plum juice), and too late might leave you with a good alcohol level but not the taste you want (i.e. a tart apple/plum cider). Good luck finding the right balance. The trick will be stopping fermentation at the right point after you add the plum juice... taste, taste, taste!