Flavours are either liquid or powders. They are concentrated materials used in small quantities. They may be supplied in bags, drums or bottles.

By definition, all flavours are at least partially volatile. It is therefore important to store them in a sealed container, away from light, heat and oxygen that may cause some degradation. Flavour may decay with age so minimum stocks should be held and stocks that have been opened and held for more than about two months should be sampled and tasted against a control.

As a matter of standard procedure a sample should be taken from a delivery and checked against a control sample. The control sample can be stored in a dark bottle in a refrigerator but be sure to compare a new sample with the control at the same temperature.

To a large extent, we rely on the sense of smell to evaluate flavours so only persons with a good sense of smell and some experience should be used to compare smells. Small strips of absorbent paper may be used to sample a liquid flavour that is to be smelt.

Although smell is probably the most critical test, for most fruit and "sweet" flavours tasting at 0.1% concentration in a 2% sugar solution may be helpful. Alternatively a small batch of the medium in which the flavour is to be used should be prepared and carefully compared by a taste panel.