Lightening the colour of protein rich flaxseed meal by bleaching it with hydrogen peroxide will improve the potential for using it as an ingredient in foods, say researchers.
Writing in the International Journal of Food Science & Technology, researchers noted that although the protein rich flaxseed meal – a by-product of the omega-3 flax industry – is nutritious and could offer functional benefits to food formulators, its dark colour –which effects the appearance of finished products – has always stood in the way of widespread use. However, researchers from Canada have now offered a solution – bleaching the flax meal to lighten the colour.
The study found that dilute hydrogen peroxide can be used as an effective bleaching agent, to produce a lighter (discoloured) brown flaxseed meal for use in the food industry.
“This research may be exploited by the food industry to improve the profitability of the flax sector using a bleached meal as a ingredient in food formulations to improve the nutritive techno-functional properties of different food products,” said the authors, led by Dr Mohammed Aider, from the Université Laval, Canada.
Aider and his colleagues noted that flaxseed is an important oil seed crop, which is mainly used as a source of omega-3-rich vegetable oil.
However they noted that the residual meal could become an important source of proteins – adding that traditionally, the meal residue was been used for feed.
“To enhance the profitability of the flax sector, it is important to investigate other ways for flaxseed meal use,” they added, noting that recent research oriented towards food applications of the meal have suggested it can be used to improve nutritional value of different food products – particularly those made of plant material.
“In this context, flaxseed meal can compensate the lack of some amino acids like lysine. Flaxseed meal can be also used to improve some functional properties of different food matrices,” they added.
Despite the advantages of flaxseed meal in terms of improving nutritional values and functional properties of different foods, Aider and his team noted that its use b the food industry is quite limited due to the dark colour of the meal.
“Incorporation of flaxseed meal to food matrices will result in product with altered colour. This attribute is extremely important for consumers,” explained the researchers.
“Based on these considerations, it seems important to investigate ways to bleach brown flaxseed meal to improve its potential as food ingredient,” they added.
The team reported that brown defatted flaxseed meal was decolourised by dilute hydrogen peroxide.
They said that the colour changes was evaluated as function of the flax meal concentration (2.5%, 5% and 10%), hydrogen peroxide concentrations (1%, 2% and 3%), pH (3, 6, 7 and 9), temperature (25, 50 and 75 °C) and reaction time (2, 5 and 10 min).
Product whiteness and yellowness were reported to be better at pH 9 and with 3% HP concentration, and was enhanced by increasing temperature.
Aider and his team said that colour values were optimal at 2.5% flaxseed meal, 3% hydrogen peroxide, and pH 9 – for 10 min at 75 °C.
“The results obtained in this study showed that bleachability of defatted FM is possible under acidic, neutral and alkaline conditions ... results may be exploited to improve the profitability of the flax sector using bleached meal as ingredient in food formulations,” they said.
Source: International Journal of Food Science & Technology
Published online ahead of print, doi: 10.1111/j.1365-2621.2011.02749.x
“Bleaching of defatted flaxseed meal to improve its usage as ingredient in food applications”
Authors: M. Aider, A.A. Martel