19 December 1997

A method developed by a University of Queensland researcher for extracting flavour from natural beverages stands to revolutionalise current food and drink flavouring practices.

Dr Suresh Bhatia from the University's Chemical Engineering Department developed the method after being approached by a Queensland company 12 months ago.

The process selectively adsorbs flavour compounds from distilled beverages onto a porous solid. The compounds are then released from the solid into a liquid flavour concentrate form.

Currently, beverage-related flavours (for example, coffee, orange juice) are synthetically manufactured.

Industrial applications would involve companies using the process to produce either liquid flavour concentrates for sale to food and beverage manufacturers or using the flavours to produce end products themselves (for example, flavoured ice-cream).

Adsorption, as opposed to absorption, involves the holding of molecules from a gas or liquid onto the surface of a solid forming a thin film. With absorption, liquid is actually taken up and incorporated into the absorbing material.

The extraction process developed by Dr Bhatia also allows producers to select the fractions of natural flavours adsorbed from beverages. Companies therefore have control of the end strength of flavour concentrates. Often numerous, even hundreds, of different compounds are involved in the overall taste of a natural product.

'Artificially-made flavours don't come close to true flavours but natural flavour extraction methods tend to be a closely guarded secret among a few companies worldwide,' Dr Bhatia said.

'Consequently, our research has started from scratch to develop a method for extracting true and natural flavours from beverages.'

A $35,000 grant from the University of Queensland Foundation Ltd will enable Dr Bhatia to refine the second part of the adsorption extraction process (optimising removal of flavours from the porous solid) using supercritical fluid extraction techniques.

This technique uses carbon dioxide at high pressures to extract flavour compounds from solid surfaces. At these pressures, the carbon dioxide gas density almost resembles that of a liquid. When the unit is later decompressed, carbon dioxide is removed leaving flavours collected in a harmless fluid.

'The project aims to optimise the supercritical fluid extraction step by studies of the effect of varying temperature, pressure and particle size. In addition, we will identify suitable co-solvents for the process, if needed, and solids with appropriate characteristics to act as the adsorption material,' Dr Bhatia said.

Experiments to derive the natural flavour extraction technique were conducted by Dr Bhatia, senior scientific officer Gary Asmussen and then PhD student Dr Rama Iyer within the Chemical Engineering Department.

For more information, contact Dr Bhatia (telephone 07 3365 4263).