Characterisation of banana skin pectin showed that the degree of methylation, an important parameter for gel strength, was wide ranging, indicating the ingredient could "probably gel with calcium or with high sugar concentrations in acidic condition," stated the researchers in the journal Food Chemistry.
Lead author Thomas Happi Emaga from Gembloux Agricultural University (Belgium) and the African Research Centre on Bananas and Plantains, also reports the ideal extraction conditions of the pectin for potential food uses: pH 2.0 for one hour at 90 degrees Celsius.
The research, published in the journal Food Chemistry, 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, mango, pumpkin and squash.
At the recent FiE in London, Dr. Steve Bodicoat, marketing and innovations direction for CP Kelco, told FoodNavigator.com: "We do experiment with other sources of pectin, like potato, for example, but we see more potential in citrus."
"There is scope to improve citrus pectin," he said.
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.
Emaga and co-workers looked at a range of extraction conditions on the composition of acid-extracted pectins from banana peels, including the effect of pH (1.5 and 2.0), time (one and four hours) and temperature (80 and 90 degrees Celsius).
They report that pH influenced the composition of the pectin, with extraction at pH 2 found to produce a pectin with a higher galacturonic acid content. Over all, the galacturonic acid content ranged from 402 to 718 mg/g of extract, they said.
"Compared to literature data, these values were higher than those obtained for pectins extracted from fresh sugar beet under similar conditions (295 to 528 mg/g)," wrote Emaga.
The degree of methylation was mostly influenced by extraction time and temperature, with values ranging from 49 to 80 per cent.
The degree of acetylation was mostly affected by temperature, added Emaga, and ranged from 1.2 to 5.7 per cent.
"All the values of the extracted pectins were low, indicating that pectins from banana peels were slightly acetylated like commercial citrus pectin," they said.
There could also be an economic interest in exploiting banana peel as a pectin source, suggested the researchers.
"Developing countries such as Cameroon import several tons of pectin each year, although there is a vast resource of agricultural products and agro wastes which can be used to produce pectin. In this country, 600,000 metric tons of banana were produced in 2004 with 40 per cent of the total weight of the fruit being wastes which can be used to extract pectin," they said.
The researchers confirmed that the physicochemical properties of the banana peel pectin were still under investigation, with particular attention being paid to the gelling properties.
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 Chemistry (Elsevier)
Published on-line ahead of print, doi: 10.1016/j.foodchem.2007.10.078
"Characterisation of pectins extracted from banana peels (Musa AAA) under different conditions using an experimental design"
Authors: Thomas Happi Emaga, S.N. Ronkart, C. Robert, B. Wathelet, M. Paquot