The process, which combines passing the waste through a resin and then ultra-filtration, produces "a brilliant and almost colourless final sample that can be used as a natural sweetener for food, drinks and, in European Union, for fruit nectars," wrote lead author Monica Scordino in the journal LWT - Food Science and Technology.
The new research, led by Emanuele Maccarone from the Università degli Studi di Catania, obtained pigmented orange pulp waste from a local processor used a neutral polystyrene-divinylbenzene (PS-DVB) resin to recover flavanones and anthocyanin pigments.
The ultrafiltration (UF) process which followed this stage removed enzymes and micro-organisms, and stabilised the product, said the researchers. The final product was found to contain about 250 g/l of sugars (33 per cent glucose, 30 per cent fructose and 37 per cent sucrose), 9 g/l of citric acid and 1 g/l of pectins.
"The concentrate, obtained from a residue that otherwise must be disposed, was a transparent liquid of slight amber colour with a very low microbial count and could easily find application as a natural sweetener in food and beverage industries," wrote Scordino and co-workers.
None of the researchers were available to comment prior to publication, and it is not known if an industrial partner is involved to further research and develop this sweetener source.
The researchers stress that, although they focussed on an analytical approach far away from an engineering purpose, the results demonstrate the possibility to obtain high-quality sugar syrup employable as food sweeteners.
"We believe that the economics of these treatments must be evaluated adequately to make this process commercially profitable; in facts even more costly methods, such us supercritical dioxide extraction, may, with investigation, yield economically acceptable applications in removal technology," concluded the researchers.
Waste disposal has increasingly found a place on government agendas recently. The EU announced at the end of 2005 that reducing the environmental impact of food waste, including cutting down on landfills, would form part of a multi-million euro, five-pronged research project aimed at the food and drink industry.
Source: LWT - Food Science and Technology
Volume 40, Issue 4, Pages 713-721
"Highly purified sugar concentrate from a residue of citrus pigments recovery process"
Authors: M. Scordino, A. Di Mauro, A. Passerini, E. Maccarone