TREATMENTS OF WATER HYACINTH TISSUE TO OBTAIN USEFUL PRODUCTS

The water hyacinth (Eichhornia crassipes) could be an inexpensive source of protein for animal, and possibly human, nutrition. The fibre is usable for ruminants. This is a pilot study on processing the plant. The samples used came from Egypt. The tissue contains many air-filled intercellular spaces and soaks up water, but is also tough as a result of fibres. It contains sharp needles formed by Ca-oxalate. Though the concentration is not high enough for toxicity, the needles could harm the digestive tract. Owing to the tissue's toughness much energy must be spent in chopping it, which results in many destroyed cells. Polyphenoloxidases are activated and the resulting quinones react with the protein, making it indigestible. So the native enzymes have to be inactivated before further processing. This could be done by adding low quantities of sulphite. Lactofermentation, a prerequisite for silage production, is possible, but only after adding sugar and suppressing mould growth. Many methods were tested in the attempt to make the protein soluble. The application of NaOH as a solvent, and also the combination of pectinase/cellulase showed the best results. It was possible to concentrate the soluble protein by means of ultrafiltration. Based on the results we propose a processing scheme. © 1990.