Tailoring the flavour of cereal products

Whole grain cereal has in several epidemiological studies been proved to be beneficial to one's health. Rye and oat are traditionally consumed as whole grains. Rye is known from its high content of fibre and bioactive phytochemicals, and health benefits of oat are based on its cholesterol-lowering function. However, in order to be used as a part of a well-balanced diet, the flavour and texture of whole grain products must meet the expectations of consumers. Flavour of cereal products flavour is formed by flavour components and their precursors together with the processing technique used. Volatile and non-volatile compounds (phenolic acids, fatty acids, sugars, amino acids) influence the flavour as such but also indirectly through forming new flavour compounds, e.g. in Maillard reaction. Intensity of flavour attributes can be related to flavour-active chemical compounds by PLS regression. Sensory descriptors of volatile compounds can be recognised by GC olfactometry. Although flavour of native rye grain is mild and bland, the intense, bitter flavour of rye products may be an obstacle for their use. Mechanical fractionation of rye grain proved that the flavour components are unevenly distributed: rye-like flavour without bitterness was observed between mild-tasting innermost part and bitter-tasting outermost bran fractions. This layer contained also significant amounts of bioactive compounds. Both sourdough fermentation-baking and germination-heat treatment influence the flavour by increasing the amounts of health-beneficial phenolic compounds. Typical intense, sour, slightly bitter flavour of rye bread crumb forms in sourdough fermentation, whereas baking results in a roasted flavour influencing mainly the bread crust. Oat products are susceptible for rancid flavour notes. Germinated oats dried at high temperatures were identified as being roasted, sweet and nutty in flavour, and concurrently the stability of oats was increased while the development of bitter, rancid taste was delayed. By applying different bioprocessing techniques, the sensory characteristics of cereal may be adjusted in a controlled way. This would provide tools for the industry to develop appetising, health-promoting whole grain products or cereal-based ingredients to a variety of applications