• Serious liquor problems

    There is a whole range of flavours, good and bad, whose impact on quality varies in importance depending on the type of coffee and on the type of buyer. But some flavours are unacceptable in any coffee to virtually all buyers, certainly in the quality business.

    Fermented or foul is a very objectionable taste, not unlike the odour of rotting coffee pulp. In its worst general form this is due to over-fermentation, cherry left to rot in heaps, the use of polluted water or stung beans with pollutants entering them. Foul-tasting cups can also be produced by single beans left behind in fermentation tanks or washing channels, or by beans that have been partly dried and then re-wetted again under unsanitary conditions.

    If a few such stinker beans are irregularly spread throughout a shipment then this is a typical example of an unreliable coffee that occasionally produces an unclean or foul cup. Note that there is no such thing as only a little ferment, just as there is no such thing as being almost honest. See also 11.05.06 about pulper-nipped beans and 11.05.07 for insect damage.

    Most buyers would also consider sour and onion liquors as totally unacceptable, arguing that both are just a step away from ferment. This is a persuasive argument because sour and oniony liquors are caused by late pulping of cherry, and poor processing or drying techniques. Coffee does not naturally come off the tree with such taints. Remember that fermentation starts as soon as the cherry is picked. But there are clever blenders who know how to use such coffees in combination with other specific taste characteristics,
    and in so doing arrive at an acceptable final result. The real issue may therefore be whether such a coffee is over the top or not. In any case, as far as the quality market is concerned one is best advised to stay well clear of such coffees.

    Musty or mouldy is a very unpleasant coarse harsh flavour caused by the storage of under-dried coffee, or the re-wetting of coffee after it has already been dried. This flavour also suggests potential mould problems - see 12.08 Mould and prevention. Earthy is a close relative. Contact with bare earth or dust are the main causes, which also imply poor drying arrangements, and the possibility of mustiness and mouldiness.

    Very strong taints will also render a coffee virtually unusable: contact with petrol for example. Unclean can refer to any offensive off-flavour or taint. It can also be taken to indicate that an unspecified off-flavour is present.

    Most of these taste defects tend to intensify with ageing. The common thread linking them all is that they are not to be tolerated in reasonably decent coffee.

    NB: The information on mycotoxins (see 12.08) on this website has been drawn from industry experts, from the findings of the ICO/FAO project 'The enhancement of coffee quality by prevention of mould growth', and from the book Coffee Futures published by CABI Commodities (2001 - ISBN 958-332356-X) www.cabi-commodities.org.
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