Researchers from University of Yaounde I, Cameroon's Ministry of Scientific Research and Innovation, and France's INRA (UR1268) report that, using an ammonium oxalate extraction process, pectins could be extracted and used a gelling agents in food.
The research, published in the journal Food Hydrocolloids , taps into the growing trend for alternative and novel sources of pectin, highlighted by an increasing number of studies looking at extracting pectin from sources such as sugar beet, pumpkin and squash.
The functionality of pectin is dictated by the chemical fine structure, and the majority of the pectin used currently comes from citrus peel and apple pomace.
Other sources of the ingredient have remained largely unexploited because of certain undesirable structural properties.
"With a good recovery yield, a high average molar mass and intrinsic viscosity and a high degree of methylation, ammonium oxalate extracted mango pectins present good characteristics to be exploited industrially for their gelling properties," wrote the authors.
The researchers investigated the potential of mango peels, a waste product from fruit processing, to offer pectin for the food industry.
Three types of extraction media were used - hydrochloric acid (HCl), deionised water, or ammonium oxalate - to extract the pectin from the peels of Améliorée and Mango varieties.
The researchers report that the peels are a rich source of pectin, "as revealed by their high content in uronic acids, galactose, arabinose and rhamnose," they said.
The ammonium oxalate extraction method produced the best results with higher yields, high molecular mass, and intrinsic viscosity.
HCl was found to partially degrade the pectins, while the water method produced poor yields.
Despite these differences, the recovered pectin from all the methods were highly methylated, which form gels with large amounts of sugar (more than 55 per cent) and acid.
Comparing the results of the extraction methods for yield, uronic acid content, neutral sugars content, the degree of methylation and acetylation, and their intrinsic viscosity, the researchers concluded that the most potential was for the ammonium oxalate-extracted pectin.
B.B. Koubala and co-workers confirmed that work was ongoing; with study currently focussing on the rheological properties of mango peels pectin gels.
Researchers from Denmark and England recently highlighted the possibilities of this ingredient and proposed that 'designer' pectin will become increasingly common in the future ( Trends in Food Science & Technology , Vol. 17, pp. 97-104).
The ingredient, with worldwide production estimated at 35,000 tonnes a year, is currently widely used as gelling agents in jams, confectionary, and bakery fillings, and stabilisers in yoghurts and milk drinks.
Source: Food Hydrocolloids (Elsevier) Published on-line ahead of print, doi: 10.1016/j.foodhyd.2007.07.005
"Effect of extraction conditions on some physicochemical characteristics of pectins from "Améliorée" and "Mango" mango peels" Authors: B.B. Koubala, G. Kansci, L.I. Mbome, M.-J. Crépeau, J.-F. Thibault and M.-C. Ralet