Spruce mill waste could rival gums for food
process waters of softwood mills could offer the food industry with
a novel source of mannans to rival guar gum and friends.
Writing in the journal Carbohydrate Polymers, lead author Stefan Willfor from Abo Akademi University, in collaboration with researchers from Oy Top Analytica and the University of Helsinki, reports that Scandinavia's milling waste may be a rich source for novel hydrocolloids. "Of particular interest is the recovery of dissolved O-acetylgalactoglucomannans (AcGGM) from process waters in mechanical pulp mills using Norway spruce as raw material. AcGGM has promising biological activity and physico-chemical properties suitable for various applications in, for example, food, health, papermaking, textile, and cosmetic industries," wrote Willfor. Galactomannans, like guar gum, are commercially important for the food industry and are extensively used as stabilizers, thickeners, emulsifiers and gelling agents. "The current use of mannans in industry is mainly limited to guar gum, Konjac glucomannan, locust bean gum, tara gum, and fenugreek gum," explained Willfor. "However, at the moment there is no industrial use of wood-derived mannans." Dr. Willfor told FoodNavigator.com that, while there is currently no use of wood-derived mannans in food, the researchers are planning some large projects where this should be investigated, with interested partners encouraged to contact his team. The review may be welcomed since the cost of nearly all hydrocolloids have increased in the last year due to rocketing energy, raw material and transportation costs, according to hydrocolloid information service IMR's Quarterly Review. Indeed, Willfor told this website: "There was a recent publication from Sweden where they had done some calculations (well, computerised/theoretical upscaling, but it looked reasonable) for production of GGM to the packaging industry. That means that the purity could be lower, of course. However, if I remember correctly they came up with a price of less than $700 per ton GGM, which is quite reasonable." In the article, the researchers discuss different extraction and purification methods, and note that despite attempts to use a variety of different solvents, the best solvent for extraction unmodified GGM is water. "Our next thought was that process waters in mechanical pulp mills already contain substantial amounts of dissolved AcGGM," wrote Willfor. "In fact, during mechanical pulping of spruce wood, about 50 per cent of the dissolved matter consists of AcGGM, which corresponds to about 5000 tons/year in a large mechanical pulp mill. "Two mill-scale trials in Finnish TMP mills during 2005 confirmed this. We managed to recover AcGGM of 70-80 mole per cent purity (the main impurities being arabinogalactans and pectic acids)," he added. Research has already looked at the applicability of AcGGM as a stabiliser for oil-in-water emulsions for food and beverages, said the researchers, with AcGGM found to be almost as good stabiliser as gum arabic (arabinogalactan). Further significant research is needed in this area, but the initial reports, pulled together by Willfor and co-workers in this review, suggest that the spruce-derived mannans could offer cost-effective and effective ingredients for a wide-range of industries. In addition, there may exist some regulatory issues with using spruce-derived mannans in food, said Willfor. "However, they are structurally very close to Konjac mannans, but have the advantage of smaller molar mass, which should be beneficial for safety reasons. "At the moment we have been working a lot with the physico-chemical properties of the GGM and some modifications more for technical purposes," he added. Source: Carbohydrate Polymers Published on-line ahead of print, doi: 10.1016/j.carbpol.2007.08.006 "Spruce-derived mannans - A potential raw material for hydrocolloids and novel advanced natural materials" Auhtors: Stefan Willfor, K. Sundberg, M. Tenkanen, B. Holmbom