Copied with permission from https://www.arishtam.com/product-page/aristam-homebrewing-guide and https://www.amazon.in/Arishtam-HomeBrew-Probiotics-Indias-homebrew-ebook/dp/B07WSXSCQY
We live in an era, where quality of food is measured by number of Instagram hits. Next three chapters will be centered on the three elements for a picture-perfect pour. Head, Clarity and Color. Aesthetically, getting the perfect head (beers) or microbubbles (sparkling wines) in the glass is the key to create an appetite for the beer even before it is sipped.
Basic Carbonation: The head is because of dissolved CO2 in the beer. When we pour it, the gases are released, which gets trapped because of surface tension of the beer (like a soap solution). To achieve foamy head:
Add ½ to ¼ tbs of sugars (glucose/ fructose/ sucrose) per pint before bottling. In 3 days these sugars will ferment, releasing the CO2 needed for the perfect pour.
Alternatively, you can force carbonate (2-4PSI) using a CO2 Tank. Mixing some nitrogen, will result in micro-bubbles (like Guinness). The tanks, refills, values and other attachments can be procured from any local fountain Pepsi or lemon soda suppliers.
For the surface tension: Add more wheat and hops to the mash. Also make sure that the alcohol is less than 7%
Clean Beer Glass: Right glassware is also very important to get the right head. The container acts as a catalyst in release of CO2.
Residual soap or Oil can alter the surface tension and ruin the foam. Hence the glassware needs to be properly cleaned, and rinsed. Milk and tea stains in utensils are hard to get rid of. They form nucleation points where the CO2 starts separating. Hence home-brewers should keep their beer glassware (Clean beer glasses) separate from the regular kitchen glassware.
Nicks, scratches and cuts in the glasses provide the nucleation points for the CO2 to escape. Hence smooth finish is needed. When served next to pool side or during house parties, people prefer plastic cups over glass. The sharp bends, ridged surfaces of plastic can interfere with the beer and make the head less prominent. So inspect the cup’s quality before pouring. Disposable acrylic cups have a smoother surface than normal PET plastic beer cups.
If the above aspects did not solve the head retention then we need to root cause the brewing process:
Right serving temperature is critical for head retention. Higher the temperature, lesser the solubility of CO2 and faster the gasses are expelled. This makes head less stable.
Mashing profile: In grain mashed beers, the brewer can control the levels of head very finely. Eliminating Beta-glucan rest, long protein rests, and having a longer duration of high temperature mashing usually solves the problem. Checking if the wort has adequate trub (to isolate the fatty acids) helps.
Make sure if adequate head forming materials are there, i.e. short to medium chain proteins. Dextrin is needed to form the foam. Enzyme mashes (Brute IPA style) and some extract styles where heavy amounts of sugar are used have this issue. Alpha acids from the hops help in making this head last for at least a couple of minutes. Adding some unfermentable sugars (crystal malts, wheat and oat) during mashing helps.
Higher levels of alcohol >7%, oily or waxy ingredients can cut down the foam. This is the reason why sparkling wines are carbonated but never have a foam.
The most common culprit is the unclean glassware used for serving and packaging (detailed earlier).
Certain styles involve ageing the beer. This breaks down proteins into peptides and hamper head formation. So check with the style guidelines.
If filtered through a less than 5 micron filter, the beer could be stripped of its body and hence head forming molecules.
There is a considerable difference between the flavor profile of regular water and sparkling water because of dissolved carbolic acid and displacement of dissolved oxygen. As a result, apart from appearance, it can also lead to different sensory notes at different temperatures. This is the reason why wine makers de-gas their red wines (through agitation or via vacuum) to get rid of these notes.
Also the foam is able to trap a lot of aromas making the beer appear more hoppy