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Toward High-Value, Zero-Waste Cassava Processing

Published: Thursday, 16 Feb 2017
Author: Lizzy LaFave
Department: Global Center for Food Systems Innovation

An important subsistence crop in Tanzania, cassava is grown in all regions of the country, yet processing constraints make it difficult for small and medium scale farmers to compete with large scale operations. To level the playing field, two researchers developed a low-cost processing system that produces high-value cassava flour with virtually no waste.

Currently in the pilot stage, the new system has the capacity to mill 500 kg of cassava flour per day. Developed by Anselm Moshi and Humphrey Ndossi, both of the Tanzania Industrial Research and Development Organization, the system is powered by renewable energy and utilizes the entire crop, including plant material previously wasted.

"The overall goal of this project is to improve income of small to medium scale farmers in the cassava value chain through innovative processing technology," said Moshi, who was awarded a start-up grant in 2015 from the Global Center for Food Systems Innovation. "There is a lot of cassava grown and it grows very quickly, but there needed to be a better system."

The researchers found room for improvement during the processing level – particularly in the drying stage. The mills that local farmers traditionally have access to do not dry the crop in a uniform fashion, which results in discoloration of the flour.

"When they use the local mills to dry the cassava, they end up with a brown flour which means it is not a high quality flour and they cannot sell the low quality flour at markets at a high price," said Moshi. "We have designed a very innovative type of hybrid dryer which uses all renewable energy sources, but specifically allows for uniform drying."

Typically, converting raw cassava into cassava flour produces an enormous amount of bio-waste in the form of peels, fiber, and even liquids. But, in Moshi and Ndossi's design, the bio-waste is converted to ethanol and used to power the cassava grating machine. Additionally, biogas is generated and then combined with solar power to run the dryer. The fibrous part of peels is used to produce a special type of polysaccharides, called prebiotics, utilized at the end of processing to fortify the flour with nutrients that can lower cholesterol.

"Cassava is a very perishable product, but it is a valued product. When you process cassava you lose about 50 percent of the tuber in the peels and pulp, and 16 percent of the tuber in liquid and gaseous waste. If you are just throwing this away, it is a big loss of product and nutrition," said Moshi. "People are most excited about the high quality flour, and (that) they can sell it at the high quality markets. But the process that generates and utilizes renewable energy to them is very cool because now they can get the better price and better product, which means more income for their families."

There is plenty of room in the flour market for economic growth from male and female farmers, and Moshi said the innovative system can help fill the gender gap. "There are a lot of women farmers in our groups that get involved. They join processing groups, or they grow cassava themselves."

Once the pilot phase of the project is complete, researchers plan to build a large demonstration site in the southern coastal zone of Tanzania.