(720b) Optimization of the Extraction Process of β-Glucans from Barley

β-glucans are non-starchy polysaccharides composed of (1-3), (1-4) mixed linked glucose polymers. They are located mainly in the cell walls of the endosperm and the aleurone layer of different cereal grains, specially oat and barleys. In general, β-glucans are a major component of the soluble dietary fibre and they influence the nutritional values and functional properties of food. Recently, several studies have revealed the benefits of including β-glucans into the diet to the human health, such as cholesterol diminution in blood, and reduction of risk of cancer, coronary heart disease, and diabetes. Although there are several papers related to the extraction and purification of β-glucans from cereals, most of them describe extraction and purification methods at a laboratory scale, which involve a significant number and time-consuming steps. Moreover, since the β-glucan content in barley grains is low (<5%) it is necessary to develop and optimise an extraction/purification method that allow reducing operation times and reactive consumption, to make competitive this product at a big scale.

In this work, research is focused on three different steps: (1) Raw material pretreatment, (2) Extraction step, and (3) Purification step. Discussion of experimental results is made in terms of β-glucan and starch content in the extracts, and molecular weight of the extracted β-glucans.

1.- Several alternatives have been studied for the pretreatment of the barley flour: ultrasonic treatment with different energy powers, enzyme deactivation and microwaves.

2.- A systematic study of the extraction variables such as: temperature, pH, extraction time, solvent ratio and solvent polarity has been performed in orde to optimize the operational extraction conditions. Extraction with subcritical water has also been studied.

3.- Two different technique have been studied and compared for the precipitation step:precipitation with alcoholic antisolvents, and precipitation with supercritical CO2.