Flavour of fermented fish, insect, game, and pea sauces: Garum revisited

Fermentation of dairy products, legumes, fish, shellfish, molluscs, and meat are considered to lead to some of the most flavourful products in cuisines across the world. The deliciousness of these fermented products is to a large extent due to compounds like free amino acids and free nucleotides, formed during fermentation, which impart umami taste, often in a synergistic fashion. We have prepared fermented fish sauces based on mackerel, using procedures as in the ancient Roman cuisine, and used similar techniques to produce experimental fermented sauces from insects (moths and grasshoppers), game (pheasant), and pulses (peas). In some cases, the fermentation has been facilitated by fungal inoculation based on a Japanese koji mother. We have performed chemical analysis of these experimental fermentation products, together with a comparative analysis of a series of commercial fish sauces, with particular focus on free amino acids and free nucleotides in order to assess the umami potential of the various products. Whereas all of the 21 different investigated sauces are found to have high amounts of glutamate and aspartate, no significant amounts of free nucleotides are found in any of the samples. The investigated sauces were characterized by quantitative sensory evaluation. Although high in glutamate, umami synergy is not expected to play any significant role for the flavour of these fish, insect, game, and pea sauces. The sensory analysis shows a fairly good prediction of sensory properties from the chemical characterization of the sauces. However, the relationship between glutamate/aspartate concentration and intensity of umami taste is not simple. It demonstrates that in the complex solutions that constitute these sauces, there may be other perceptions that interfere with the main umami-tasting compounds.