More on Flavours

Essential oils

An essential oil is a volatile mixture of organic compounds derived by some physical process, for example, distillation, expression or solvent extraction, from odorous plant materials. A specific oil is derived from one botanical species with which it agrees both in name and odour. The most commonly used essential oils in biscuits are the citrus oils from lemons and oranges.

Oleo resins

These are solvent extracted compounds remaining when the solvent has been evaporated. They are very concentrated and often caustic, even more caustic than some of the essential oils. Some commonly used oleo resins in biscuits are bun spice and ginger. As oleo resins are very concentrated they are often treated to form solutions or powders.

Synthetic flavours-GRAS

By sophisticated chemical analysis it is possible to identify the individual compounds that make up a particular scent or flavour. It may be uneconomic to extract the flavour element from the original source but chemically synthesised ingredients can be blended in the same proportions as were found in the natural flavour. Flavours made in this way are described as "nature identical flavours". The inference is that natural flavours are safer than concoctions made up by a flavourist from a library of aromatic chemical compounds but logically this cannot be the case.

The chemicals used for flavours must have an acceptability for use in food and the term Generally Accepted As Safe (GRAS) is frequently seen in connection with synthetic flavours.

It will be appreciated that there is a never-ending possibility of flavour blends that are possible from the various synthetic and natural flavour compounds available to the flavourist.

Other flavouring substances

In addition to the broad groups described above there are many other substances commonly used to flavour biscuits. Examples are cheese powders, dried autolysed yeast, dried meats and extracts, vegetable protein hydrolysates, dried and diced nuts and fruits.

The form of the flavouring material

Ground spices and herbs are obviously powders of varying granularity. Extracted oils and most of the synthetic flavours are liquids. Oleo resins are naturally liquids or viscous pastes. It is important that the flavouring material is at a concentration and in a form that is suitable for the application. Liquids can be diluted with a suitable solvent, commonly used solvents are alcohol, propylene glycol, vegetable oil or water. Liquids can also be made into powders by adsorbing them onto salt, rusk or dextrose etc. The powders can then be weighed, dusted or premixed in a more satisfactory way than small quantities of liquid or paste.

It is also possible to micro-encapsulate liquid flavours with a vegetable fat of suitable melting point. The process is expensive and, at least, for biscuits this form of the flavour is not commonly used.

Flavouring of biscuits

If we concern ourselves principally with the introduction of aromatic ingredients as a contribution to flavour it can be seen that biscuits and other cooked products may be flavoured in three principal ways:

  1. By including the flavour in the dough or batter before baking.
  2. By dusting or spraying the flavour after baking.
  3. By flavouring a non-baked portion such as cream filling, icing, jam or mallow which is applied later.

The conditions experienced during baking are very severe for aromatic compounds. They are easily removed by heat because, by definition, they are at least slightly volatile at mouth temperatures. In general, liquid flavours are not to be recommended in baked products especially those with doughs containing high levels of water such as crackers and hard sweet types. Some means of protection is needed and the sealed cells of plant tissues are somewhat successful in this. Thus, ground ginger is better than a liquid ginger extract.

There are some flavours that are found to be better than others in baked products; notable are vanilla (or synthetic ethyl vanillin), butter, cheese, almond essence, and roasted materials like chocolate, coffee and caramel also smoke flavours. Flavours that are protein based such as hydrolysates are more stable to baking temperatures but can be drastically changed if even slightly burnt. Cheese is an example of this.

Spices generally survive baking better than blended flavours or extracts.

Flavours applied after baking

These can be of any type but more savoury types find use in this area than flavours associated with sweetness. The flavours may be dispersed on a cereal or dextrose base and dusted onto an adhesive surface, like an oil film, over the product or sprayed on as solution in edible oil. Either way the system tends to be messy and causes strong odours in the vicinity.

The techniques generally are not ideal for products like biscuits, which have lower surface areas for a given weight than potato crisps or extruded snack products.

Flavours in creams and jams

Normally, essential oils and other liquid flavours find their best use in these components of biscuits. Advances in the flavour industry have resulted in excellent reproductions (or nature identical mixtures) of fruit, nut and other exotic flavours and their use in non-heated parts of a product are in general extremely successful.

Points to remember in the use of flavours in these situations include-

  1. The acidity and colour of the base is of very great importance to the acceptance of the flavour when eaten.
  2. The correct strength is important. Often there is a saturation level to the taste. Conversely, too great a concentration may result in lingering and unpleasant after-tastes.
  3. The texture of the base, especially if it is not readily soluble in water is most important. The dispersion of the flavour if it is a powder must be watched.
  4. Acids, flavour enhancers, sugars or salt should be of the correct particle size to allow correct solution speed in the mouth relative to the sensation given by the flavour compounds.
  5. Where fats form an important part of the product, as for example, in biscuit creams, melting characteristics must be matched to body temperatures and ambient conditions to allow optimum flavour release on eating.