(529d) Detoxification of Coffee Pulp by Ligniculous Fungi

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Efforts devoted to the efficient utilization of agro-industrial residues have increased, especially if this use contributes to the support of sustainable, integrated and environmental friendly processes. Coffee pulp/husk is the main byproduct generated during coffee processing.  In Puerto Rico, the annual consumption of coffee reaches 20,000 tons. If we consider that only 6% (by weight) of the coffee fruit is devoted to consumption, the amount of waste generated by coffee processing is astronomical. To reduce the pollution from the accumulation of coffee pulp, and to reutilize this still exploitable source of energy, it is necessary to establish new treatments to bio-transform this material. Among the toxic substances included in coffee pulp are caffeine, lignin and polyphenols. The presence of these substances limits their recycling and makes their management an environmental challenge.

This study focuses on the isolation and characterization of fungi which might be able to detoxify coffee processing waste, in order to convert them into useful materials such as animal feed or other forms of energy. Among the activities we are screening for are decaffeination and delignification. Thus far, we have identified Alternaria alternata as potential candidate to degrade caffeine. This strain was identified from a screening done using a ligniculous fungi collection provided by the Forest Products Laboratory in Madison, Wisconsin. A. alternata has been evaluated in terms of caffeine degradation as sole source of carbon and nitrogen. Under these conditions only a small decrease in the caffeine content is observed. The same is observed in cultures of Aspergillus tamarii, a known caffeine detoxifier. However, a preliminary analysis shows the ability of this fungus to reach a 50% reduction of caffeine content in the presence of sucrose under agitation. A parametric study and possible use of this biological system to recycle coffee pulp is discussed.