However, edible plants have also been busy evolving in tandem, and many have adapted to produce bitter tasting chemicals that are quite harmless, and often beneficial for us. They have effectively been trying to trick us into not eating them, but we are not fooled. In the evolutionary race our bitter taste sense has become more sophisticated, so we can differentiate the toxic from the non-toxic, even though our bodies will often respond to a non-toxic bitter tasting food as though it might still be harmful. The net result is that at this point in time our bodies are primed to positively respond to bitters, maximising the chances of eliminating toxins and setting up the digestive system to work at optimum efficiency.
The primary effect of bitters is on the digestive system. When using bitters deliberately they should be taken as a liquid, as any attempt to try and disguise the bitter taste by administering them as pills or capsules render them virtually useless: because the physiological response is directly triggered by taste.
The immediate result of stimulating the bitter taste buds is the release of a gastro-intestinal hormone, gastrin. Known physiological actions of gastrin are that it increases:
- Appetite (by acting directly on appetite centres in the brain) if appetite is suppressed
- saliva production
- Gut peristalsis
- Gastric acid and pepsin secretion
- pancreatic digestive secretions
- intestinal juice production
- hepatic bile flow
- hepatic bicarbonate production
- Brunners gland secretion
- intrinsic factor production
- insulin, glucagon, and calcitonin secretions
- muscle tone of the cardiac sphincter
- muscle tone of the stomach and small intestine
- cell division and growth of duodenal mucosa
- cell division and growth of the pancreas
From this exhaustive list we can see that bitters not only increase appetite but also aid digestion, accelerate stomach emptying and protect gut tissues. Of course, this has been known for centuries as many aperitifs have their origins in herbal bitters taken to stimulate the appetite and digestion made sluggish by an over rich diet.
The effect of bitters on the liver is interesting as it promotes bile flow and improves liver function by preventing the accumulation of waste materials. This is especially important where there is an unhealthy diet, excessive alcohol intake, defective digestion, chronic gut conditions or general ill health. It is also useful where long term use of conventional drug treatment has taken place, or for detoxing from recreational drugs.
Bitters should generally be avoided in pregnancy as they can cause uterine stimulation and miscarriage. Also people with gastric ulcers, ulceraitive colitis and Crohn's disease should steer clear. Generally though, used in the correct dosage, unwanted effects in healthy people are uncommon. Some people might experience headaches, muscle aches and malaise when they start taking bitters, which may be due to the detoxifying effect, and it usually subsides quickly.
Classification of Bitters
It is useful to group different types of bitters according to their usage and effects, although this is not an exact science as many botanicals can safely fit into more than one category. The classification below is geared towards therapeutic prescription rather than as a key for bar tenders, but still very useful!
Tonic or Simple Bitters
These consist of bitter principle only, and are often taken on their own. Examples include Gentian root, Quassia, Centaury.
These have bitter and at the same time, aromatic principles. "Aromatic" means based on volatile oils, which give the plant its particular aromatic flavour. The oil often has its own medicinal action, which is why some herbs are so multifunctional. A great many herbs fall into this classification, especially herbs from the mint (lamiaceae), carrot (apiaceae), and sunflower (asteraceae) families of plants. Examples include Angelica, Rosemary, Celery, and Dandelion.
Hot or Acrid Bitters
These are pungent and often used as spices. Obvious examples include Ginger and Black pepper.
These contain tannins
If you are making your own liquid extracts there are several factors to take into consideration before you get started. Obviously you goal is to get the best possible quality plant material that will yield the right mix of compounds for the desired flavour. They key success factors are:
- Are you going to use fresh or dried plant material?
- Which solvent are you going to use for extraction?
- If alcohol, what percentage of alcohol do you need to extract the right spectrum of compounds?
- How do you prepare the plant material, and which parts of the plant do you use prior to immersing in the solvent?
- How long should you mascerate the tincture?
Fortunately for most botanicals these questions are relatively straightforward, although there is a wide variation of opinion. For example, there are distinct difference between herbalists on either side of the Atlantic on the strength of alcohol used for making many plant tinctures, which one suspects is down to the availability of pure alcohol, how much duty is paid. As a general rule European extracts contain less alcohol during the extraction process. The strength of the alcohol is important, and it is important to consider the following:
- Below 25% in the finished product will not be sufficient to preserve the tincture. At less than 25% certain bacteria can survive and spoilage can happen quite quickly, particularly if using fresh plant material
- If you are primarily interested in water soluble compounds, such as tannins, some alkaloids, and flavonoids, and polysacharides, then 25 - 35% is what you should be aiming for
- To properly extract fat soluble oils, including many of the aromatic volatiles, you need 45% or more.
- Given that there will be variation in the alcohol concentration amongst different plant extracts, when you mix them together the overall concentration of alcohol will change, and compounds that are extracted at higher concentrations may precipitate out of solution when mixed with the more water soluble ones. This is what happens when you mix Ouzo, for example, with water and the drink goes cloudy.
- In general, for the more aromatic mixes, 45% is a good level to aim at in the finished mix, as you will still have some of the water solubles and the oils will stay in solution.
There are no hard and fast rules for designing a mix, as it is ultimately an art. However, it is useful to know the relative strength of a botanical in terms of how it is going to contribute to the finished product. The eugenol in cloves, for example, will dominate, and if you add a little too much you will instantly have a christmas product. Similarly, hot bitters should be used very sparingly. Tannins lend a dryness to the overall mix, and will help to raise some of the more delicate flavours.