At this time of year the brewers mind starts to mull over the likely impact of the hop harvest. With the cones mature on the bine and harvest in full swing, for some brewers, this means using green hops to brew a celebration beer. It was 20 years ago that Wadworths brewery in Wiltshire first brewed Malt and Hops a 4.5% abv beer made from green hops. They claim to be the first UK brewery to have brewed a beer from green hops and they have continued to brew it ever since. Other brewers have joined in the practice for example last year the Ramsgate Brewery brewed their beer within 12 hours of the hops being picked. Eddie Gadd, head brewer at Ramsgate, dubbed the beer Beer-jolais in a nod to the practice of vineyards competing to bottle the first Beaujolais.
What are green hops?
Green hops are hops that have been freshly picked and are waiting to be dried. Hop drying is a crucial process required to guarantee the stability of hops during storage. After picking the hops are dried using temperatures between 55ºC and 65ºC, reducing the moisture content from approximately 75% to 9%. The assertion is that during the drying process some of the rich aromatic oils that contribute the distinctive hop aroma are lost. By using green hops the brewer can preserve this aroma.
Can the home brewer use green hops?
The simple answer is yes if you can find them. It is difficult to find green hops and most home brew shops will not stock them as there is the issue of deterioration of quality. The best way of getting a supply of green hops is to grow your own and we have an article that discusses how you can do this. Click here to read this article. In terms of brewing it is my humble opinion that it is best to use green hops for late hopping of your beer as this is where the aroma will be best captured. Because of the high moisture content of green hops you would have to add significant quantities to the boil to achieve the bitterness levels that you would expect in a beer.
How do you brew with green hops?
Most home brewers, if they grow their own hops, won’t know the oil or resin content of their hops so won’t be able to accurately calculate the bittering or aroma potential. If you know the variety of the hops that you are growing you can assume an average value from previously published data. For example I have grown Goldings in my garden, a great aroma hop, it has a low to medium ?-acid content with published data suggesting a value of 4 – 7%. If I was trying to brew 50 litres with a specific gravity of 1.050 and 30 bitterness units and I was to use normally dried Goldings hops I would need to add around 100 g of hops. However if I was to use my home grown Goldings where the moisture content may be anything up to 80% I would need to use nearly 1 kg of green hops.
Clearly this is not very practical and so once again my recommendation would be to use green hops for aroma only, adding them at the end of the wort boil or even direct to the fermenter in a little muslin bag.
If you are an extract brewer then you can still utilise green hops and is fairly straightforward. I have used green hops and achieved good results by adding a muslin bag to the fermenter as you are dissolving your extract. For example if you add a muslin bag of hops just after you have added boiling water to help dissolve the extract, but before adding cold water to make up to the correct volume, there is good extraction of the aromatic hop oils whilst additionally sterilising the contents of the bag. If you leave the bag for the duration of fermentation the final hop aroma will be fantastic.
As with all home brewing there is an element of experimentation involved, which is the majority of the fun, but some good results can be achieved by using green hops and it is always a great way to celebrate the new hop harvest.