Q. Flavour of food product?

Flavour factors include both sensations perceived by the tongue, which include sweet, salty, sour and bitter tastes and aromas perceived by the tongue and nose, respectively. Flavour is a combination of both taste and smell (aroma or odour), and is largely subjective, and therefore, hard to measure.

Flavour is also influenced by colour and texture. We associate certain flavours with certain colours. For example, cherry, raspberry and strawberry flavours, although are colourless compounds, we associate them with colour because in nature they occur in food of a typical colour. Similarly, texture can be also misleading evaluation of flavour. To site an example, when you are asked to judge two identical samples of gravies or soups differing in their consistencies, it is very likely that the thicker gravy would be accepted better because of its richer flavour, although it has been thickened with a tasteless tarch or gum, which in no way would have contributed to the flavour of the product. This can be entirely psychological. The line between psychological and physiological reactions is not always easy to draw. Our taste buds respond in a complex fashion, which is not yet fully understood.

Flavour can be measured either by using sophisticated instruments such as gas  chromatography that measures specific volatile compounds responsible for that  particular  flavour or through sensory methods. Acidity can be measured by titrating with alkali or using a pH meter. Although, when it comes to consumer quality acceptance, there is still no substitute for the measurements made by having people taste products.