Introduction: Marrow Beer From Homegrown Ingredients
Ever wondered what to do with a glut of courgettes or marrows? It's always such a shame to throw them onto the compost heap when they taste so nice. Of course, the seeds are a bit of a turn off if you want to eat them, but these are not a problem when making beer.
Why is this a beer recipe and not a wine? The difference is that we are going to use hops, which, like the courgettes, are easy to grow and taste absolutely fantastic!
Ingredients for 4.5 litres of beer: 10 large marrows, 25g fresh hops, 5g brewer's yeast and NO ADDED SUGAR!
Step 1: Select Your Equipment
I've used a nice big 7 litre stainless steel pan, a 4.5 litre open necked glass jar and some 2mm garden nylon mesh used over carrots to keep off the insects. The pan needs to be about twice as big as the jar as, a bit later on, we are going to strain out the seeds and fibrous residue before the liquor goes into the jar. Why do we need to do this? If we dont, when the liquor ferments it will cause the residue to rise up to the surface and froth out of the top of the jar making a horrible mess. This is also why I'm using an open necked jar, rather than a demijohn, so as to reduce the chance of extreme frothing.
Another really useful bit of kit is a manometer as this can be used to estimate the final strength of the beer. Just remember that the liquior must be at room temperature (20 degrees C) for it to be accurate. Personnally, I'd like my beer to be at least 5% alcohol so will want the starting point, in terms of original gravity (OG), to be at least 1032.
Obviously, the equipment used needs to be clean, but, additionally, the glass jar needs to be sterile. Sterilisation can be done with proprietry products such as campden tablets, or, if your jar is resistant to hot water, hot water at 95 degrees C will kill most bacteria. Remember to rinse away any chemicals used with potable water. Wash any mud etc. off the courgettes.
Step 2: Cooking the Marrows - the Cook
Firstly, add 200ml of water to the pan and put it on the gas and start chopping up the marrows. Fill the pan with the chopped pieces and watch them shrink into the water as it boils. Dont start with too much water as the liquor will be too weak and will be low in sugar content and have no taste. Marrows themselves have about 2.5% sugar content , which is not very much to produce a good beer, so it would be a good idea to get the liquor as strong as possible by limiting the amount of water used to a minimum and even boiling off water water on to reduce the water content. Marrows are about 95% water!
As the chopped marrows shrink in the boiling water, chop up some more and add them when there is room in the pan. Keep doing this until the pan is full. Boil off water as required to get the right strength.
Cook the chopped marrow for about one hour to break done the fibres and starch and release the sugars.
Step 3: Removing the Pulp - Pulping!
Pulping is a technical term that I have invented for straining the pulp from the liquor. It's quite simple - just pour the contents of the 7 litre cooking pot into the bucket through the 2mm mesh. The pulp will be left on the netting and, when it is cool, can be gathered up in the netting so that it can be squeezed into a ball, thus extracting as much liquor as possible.
This would now be the stage to test the specific gravity, or the sugar content, of the liquor. Pour some of the liquor into a tall beer glass and leave to cool to 20 degrees C. Carefully drop the manometer into the liquor, ensuring that it is floating and not touching the bottom. Take a reading at the miniscus level.
Another important test to perform - taste the liquor! Does it taste nice? Does it have intensity of flavour or is it weak and insipid?
I found that the sugar content was not strong enough from doing just one 'Cook' - only OG 1014, so decided to repeat the whole process but instead of using water, use the liquor from the previous cook. You could, of course, cheat and add sugar, but I would not recommend this myself as the liquor proably does not have enough flavour at this point anyway. I ended up doing 3 cooks with this batch.
Step 4: Add the Hops
I am lucky enough to have fresh hops just about ready to harvest - I just need to check that they are ready. If you cut the hop open, you should see yellow lupilin powder inside the hop. Also, the hop can be tasted and should have a really bitter hit. Alternatively, dried vacuum packed hops can be bought mail order from most good homebrew suppliers.
I'm going to use about 25 grammes of hops, based on previous experience and based on my own personnal preverence for a nice American style craft beer.
All pulp should be removed and the liquor now boiled for 90 minutes to get the full flavour out of the hops.
Step 5: Pitch in the Yeast
Allow the liquor to cool to at least 25 degrees C, strain out the liquor to the 4.5 litre glass jar, do a final check on the specific gravity and sprinkle the yeast into the jar. Now cover the jar with a piece of kitchen cling film or such like and store in a warm place at, ideally, 20 degrees C. I managed to get this particular batch to OG 1032, which I'm very pleased with.
A slight improvement on the process would be to create a 'starter' yeast culture in a jam jar whilst waiting for the liquor to cool. Simply decant 100 ml of liquor into a 150 ml jar, allow it to cool (it will cool a lot quicker than the main batch) and sprinkle half the yeast into it. Seal with cling film - not the lid or it will explode.
Primary fermentation should be over in ten days, after which the brew can be racked off into another jar, leaving most of the sediment behind. Secondary fermentation times depend on the OG of the brew, but should be complete after another four weeks.
Now the beer can be bottled in the normal way or poured into a small keg and gased up with CO2.
Next beer project - beer from sugar beet, if I can find some.
Step 6: Tasting Session on Video
Step 7: Hot Tips
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