Somewhat surprisingly, truffles have a very high protein content, which is why they are often described as 'vegetable meat'. White and black truffles have the same chemical content and are made up of 73% water, the remaining weight comprising several types of minerals and organic substances such as calcium, potassium and magnesium. There have been a number of studies made to find out why pigs simply go 'mad' for the tuber and why it was mainly the sows (female pigs). At one point it was understood that they were detecting an androstenol (5 -androst-16-en-3 -ol), a steroid alcohol which has been identified in truffles and is also in a boars' saliva. It was a French chemist called Thierry Talou who conducted an experiment hiding samples of fresh truffles, androstenol (5alpha -androst-16-en-3alpha -ol) and some synthetic truffle aroma without the 5alpha -androst-16-en-3alpha -ol. The conclusion was that the pigs ignored the androstenol (5alpha -androst-16-en-3alpha -ol) but showed interest in the real truffles.
The fresh truffles contain a number of organic molecules known as alcohols, aldehydes and ketones. The smell of the truffle is actually due to a molecule known as dimethylsulphide or CH3SCH3 (which is also found in asparagus) along with a collection of others. These molecules are also known as 'volatiles'. Amongst the main varieties of truffles, the relative quantities of alcohols to aldehydes to ketones varies, but they all contain dimethylsulphide molecules.
More than 200 volatile organic compounds have been to date described from various truffle species. A single species typically contains between 20-50 volatiles, and the composition of these volatiles might depend on geographical location and/or maturity.
When the truffles are kept over a period of time the volatile sulphur compounds escape faster than the other molecules. It is the release of the dimethylsulphide (CH3SCH3) molecules along with CH3CH2CH2SCH3 and CH3CH=CHSCH3 into the air that give the truffles that strong pungent smell.
Reviews on the available data on chemical composition and nutritional quality: moisture (75.21-79.38 %), protein (19.59-27.18 %), fat 92.81-7.42 %), crude fiber (7.81-14.89 %), ash (4.33-6.39 %), and ascorbic acid (0.70-5.10 mg/100 g). It also contains high amounts of K, P, and fair levels of Ca, Mg, Na, Fe, Cu, Zn, and Mn. Reports show that truffle contains all essential amino acids.
Fungi are an important source of primary and secondary metabolites and have for long been exploited by the pharmaceutical and food industries. A large number of these metabolites can thus be described in terms of their usefulness to our human society (i.e. benzaldehyde, a volatile with a typical almond odor, is the most exploited aroma of the food industry, or citric acid.