Downstream processing for kaukau

By JOEL G. WARAMBOI
SWEET potato (kaukau) is widely grown in Papua New Guinea and is an important staple crop.
A high proportion (more than 80%) of the rural population grows it either as a minor or major staple crop. Production has increased over the years and, especially, since the devaluation of the PNG currency in 1997.
Current annual production is about three million tonnes with 75% produced in the highlands. It is less important in the lowlands where the land is subject to inundation.
While sweet potato remains a subsistence crop, mainly for home consumption as food and animal feed, a significant amount is sold each year. These are sold locally and at urban markets in Madang, Lae and Port Moresby. And consumers have a high preference for sweet potato, provided that price and quality is acceptable.
While the crop has vast potential, its current use and consumption in the country is in the form of boiled or roasted tubers and usually fed fresh to livestock, especially pigs.
The potential of sweet potato in food security and global well-being has been well recognised with studies performed on its various properties to underline processing, utilisation, functional, nutritional and health importance. While these potentials have been explored elsewhere, Papua New Guinea has made no attempts to explore these options, particularly in terms of downstream processing and value addition.
In the past, some research and product development work was done at the University of Technology into products like flour, chips, crisps and composite bread. Recently, NARI successfully released sweet potato-based feeds (silage) for pigs.
Experiences from Vietnam and China have shown that the crop could be utilised for livestock production where it constitutes 70% of pig feeds.
Past and current research and development work on sweet potato suggest that it has the potential to be a commercial crop. On-farm processing of sweet potato could form an additional income-generating activity where a constant supply of the fresh tubers and demand for processed products is secured.
With appropriate policy and investment, there is potential to transform it from its currently under-utilised status to a commercially viable one.
New research by the author on flour, starch and processing properties of sweet potato since 2009 at the University of Queensland is generating valuable information that could trigger industry development of the crop. Under this study, selected PNG and Australian varieties are being processed into ready-to-eat pasta (noodle-like) products using extrusion cooking technology.
The studies have indicated that sweet potato can easily be extruded by controlling processing conditions like moisture content, screw speed and temperature to produce high quality nutritious products. These studies are also generating vital information on process engineering, energy input, flow properties, cooking characteristics, nutrient retention and product quality as well as protocols for cultivar selection, unit operations and flour milling.
Sweet potato processing is increasingly being commercialised in many countries in Africa, Asia and the United States. While these countries are using advanced processing facilities, PNG could use low-cost extrusion equipment.
Such equipment are available, costing A$10,000 (K24,000) with production capacity of 30kg/hour. These equipment have successfully been used in rural communities in Vietnam, China, Peru and Kenya to make noodles, pasta, vermicelli, flakes, crackers, puffs and other products.
Besides extruded foods, these communities have also used sweet potato flour for substituted biscuits, bread and scones while fresh tubers have been processed into chips and crisps.
Currently, fresh sweet potato tubers are sold at around K2 per kilogram in the open markets in PNG. Although there are no statistics, rough estimates indicate that, if processed, the dry flour could cost as low as K0.80 per kg, providing a cheaper product compared to wheat flour. This means retail margins can be relatively good for entrepreneurs.
Processing not only increases the utilisation and consumption but also fetches premium prices if sold, increases cash income opportunities and reduce handling for growers. Sweet potato processing technologies are relatively simple and can be adopted easily through farmer cooperatives and women’s groups at farm level.
Generally, there appears to be a strong and all-year round demand for processed products. Changing food habits, increasing urbanisation, adapting to climate change and increasing population are all positive factors that can make food processing a viable option in PNG.
We should also take a stock of what and why the industry has not developed over the years.
If past investment options (if any) have not worked, what other models and options can we try?
How about setting up an organisation specifically mandated to drive development in this sector? It is about time, that the food and agriculture sector takes this course to revolutionise its potential.
Until and unless this is done, crops like sweet potato will continue to be treated as a poor man’s crop.
Downstream processing and value addition has the potential to benefit en mass, raise the economic value and create market demand for local crops. It will also improve food security and cash income levels, increase trade and replace/substitute imports, thereby contributing to broad-based economic growth and improvement in the living standards of ordinary people.