Feasibility of producing a spirit from waste bread koji

Food waste is a global issue, and a significant sustainability challenge. It accounts for 8-10% of annual CO2 emissions and is a strain on resources such as raw materials, water, land and energy. In the UK, bread accounts for a significant proportion of food waste, with an estimated 960 tonnes wasted every day. There has been substantial research into the conversion of bread into valuable products, such biofuels, biohydrogen, lactic acid and 2,3-butanediol, and its use to produce alcoholic beverages is another promising application. With sustainability in mind, a novel technique is to cultivate koji fungus on the raw material to provide a source of starch degrading enzymes, as opposed to the energy intensive malting process in brewing. Koji, traditionally used in production of a variety of Asian alcoholic drinks, is a grain, such as barley or rice, that has been cultivated with koji mould, which includes various species of Aspergillus fungi. Koji fungi produce enzymes, such as amylases, which break down carbohydrates into fermentable sugars. These sugars can then be fermented by yeast to produce alcohol. This study investigated the feasibility of producing, on a commercial scale, potable alcohol from waste bread and various strains of koji fungi, with analysis of the volatiles and flavour profile of the spirits.