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Agrifood by-products disposal problems

In the agri-processing sector, liquid co-products and by-products have for a long time generated much interest and research into ways of reclaiming some or all of their valuable components. For example, worldwide more than 177 billion liters of whey (cheese and WPC) are produced annually, however less than 40 % of that amount is transformed into whey powder.

IDF Symposium on Lactose and its derivatives. Moscow, Russia. May 14-16 2007.

In the province of Québec territory alone, cheese production generates 1,2 billion liters of liquid whey, a figure which represents more than half the overall canadian production.

Generally, in milk and cheese processing four (4) main alternatives are available : (i) upgrading the value of whey through fractioning, (ii) drying of whey, (iii) spreading onto crop fields, and finally (iv) disposal into municipal treatment systems.

Efficient upgrading of whey is carried out mostly at large processors, who are able to afford the required investments. The methods used are either direct drying, or ultrafiltration in order to recover proteins and extract lactose.

With regards to direct drying, the cost of the initial material is relatively low, but the process itself consumes significant amounts of energy; in the case of spreading or pumping into municipal treatment systems, companies often must pay a fee. It is also possible to recover derivative fractions but these processes still generate large volumes of carbon-charged liquids.

Major yeast producers have little use for such types of agrifood raw materials, since the fermentable carbohydrate contents are too low to apply to existing manufacturing configurations when compared with molasses, the preferred substrate. . Dairy by-products could be used if a pretreatment step were applied to convert lactose into monosaccharides since Saccharomyces cerevisiae, unlike Kluyveromyces marxianus (ProLactis^TM), cannot utilize this milk sugar.

Meanwhile, for companies wishing to dispose of passed-date or off-spec alcoholic and soft drinks, often the only available treatment is pumping of the liquids into the municipal system after neutralization with an alkali such as caustic soda. This method calls for a pre-treatment station, and involves automated controls, maintenance, and other costs. Those companies are moreover dependent on the network they’re part of, and are subject to fines and increases in user fees, without any practical alternatives.

Whereas economical considerations represent the main argument in convincing such potential users of the ProLactis^TM technology, the continuous tightening of environmental regulations will help in developing this market sector. By the same token, corporations that generate significant amounts of any low-value liquid by-product understand that they need to keep an outstanding corporate image for the sake of their shareholders and in the public eye as well.