The application of hybrid membrane processes to fractionate gum arabic into streams of added value

Gum Arabic is a water-soluble hydrocolloid extracted from certain Acacia trees native to sub-Saharan Africa. This gum exudate is widely used in the food industry as an emulsifier and stabiliser for oil-water interfaces.

This paper reports the separation of Gum Arabic, which is comprised of three fractions, each of different structures, molecular weights and functions:-

(i) 2 % Glycoprotein (GP) - 250 kDa
(ii) 88 % Arabinogalactan (AG) – 280 kDa
(iii) 10 % Arabinogalactan-protein complex (AGP) - 1500 kDa

The highest MW fraction (the AGP complex) has been shown to facilitate emulsification. Consequently, high proportions of this fraction are industrially desired in commercial products. The generation of an enriched AGP stream would add value by reducing the amount of product required for a particular emulsification application.

This paper reports the use of multiple-step synthetic membrane filtration processes (aka ‘hybrid membrane technology’) to separate the gum fractions and investigate their functionality, both as individual fractions and as different blends in order to create new, higher value products.

Permeate flux, Volume Reduction Factor and species transmission data are presented for flat sheet polymeric ultrafiltration and microfiltration membranes. The nature and extent of the membrane fouling is described, and strategies for regenerating the membrane are presented. The functionality of the output streams is key – this has been characterised, and is also described.

Acknowledgements
This project has been supported by Kerry Foods, Draycott Mills, Cam, Gloucestershire, UK