Chapters 8.47
8.47-Yam Value Addition
Zachary McMullan, University of Guelph, Canada
Suggested citation for this chapter.
McMullan,Z. (2022) Yam Value Addition,In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org
Introduction
The yam family (Dioscorea spp.) includes about 450 species (Girma, 2015). Compared to other root crops such as sweet potatoes and cassava, yams are preferred and fetch higher prices (Rubatzky & Yamaguchi, 2012). The largest fraction of yam production is conducted by subsistence farmers (Rubatzky & Yamaguchi, 2012). This dependence on the yam by smaller independent farmers emphasizes the need for the expansion of post-production value addition, and the continued exploration for the use of the yam. More than 95% of the world’s yam production is in Africa, of which >75% is in Nigeria (Rubatzky & Yamaguchi, 2012). As the yam is most commonly grown by farmers in developing countries, simple methods of value addition are needed
Yam jam
One idea for a yam value addition revolves around the creation of a yam based jam. The creation of this product would require rather simple tools, as really any hard tool or object can be used to mash the firm tuber into a paste like substance. There would be no electricity required in the creation of this product as this mashing can all be done by hand. The paste could then be mixed with any local spices that are common in the community to add a blend of tastes and establish new lines of similar products (as different farmers may experiment with different spices and mixtures). After the yam has been mashed and mixed into a spiced jam, it can be stored easily as a final product in any jar or container. If methods of proper preservation are available, such as keeping the product cold, then the jars will allow for easy storage and transportation to local markets. Likely these methods would not be available, evident by the fact that a subsistence farmer may only have 12 hand tools at their disposal (Swinton, 1988). However, jars would still allow for improved shelf life as the food will not be exposed to oxygen (Burton & Wigginton, 1970). Improved shelf life will allow for a better profit margin. The main issue with the production of this product, and really any yam value addition, is that: “yam preservation is extremely challenging (Verter, 2014).”. With that being the case, the product would need to quickly establish itself in local farmer’s markets in order to minimize waste losses and maximize economic gains. With yam being common in developing countries, and a pre-existing appreciation for the taste, the product should be able to combat the struggles of preservation with a wide variety in its uses, as the jam like substance would be easy to apply to any dish. Potentially some recipes could even be boiled and eaten raw as a sort of mashed yam.
Yam chips
Furthermore, another yam value addition idea is the production of a yam based chip. Snack foods are now common across the globe, and the chip is amongst the most adored. The Irish potato was the inspiration for the modern day chip. For subsistence farmers, yam chips may be more appropriate. These chips would provide a much better nutritional value then many commercially processed potato or corn flour chips. This is evident by the fact yams are nutritionally more desirable than other tropical root crops, particularly in protein content (Wanasundera & Ravindran, 1994). Therefore, the by-product chip would be a healthier alternative. Only basic cooking skills are required as generally the chips could be baked over a common fire. First in terms of post-harvest production, a farmer would need to slice the yam into thin sheets using any knife or blade at their disposal. The yams could be peeled of the rough outer exterior to provide for a softer chip and overall improved product, however this would increase the amount of required labor and is not necessarily essential for production. As previously mentioned with the yam being difficult to preserve, it may not be worth the extra steps in terms of the farmer’s time and the ability to maximize the yield. After the yams have been sliced, the product could be processed in two ways. They can be bagged and stored for sale, and as when sold in bulk, the consumer may want to bake the chip themselves for a fresher result or to preserve shelf life (chips once cooked would have to be consumed rather quickly due to the lack of preservatives). Or the chips could be baked by the farmer, either in a rotisserie fashion over a common small wood fire, or with the use of any kind of firewood or stone oven. This would increase labor output but would allow the product to be sold or traded off quickly as a treat or snack in smaller local markets. Quick movement of the product is key in order to prevent any issues revolving around preservation and quality of the product. As the chip is similar to many commercial products favored in developed countries, farmers or local business’ could advertise the chip as a sort of modern commercial product, using fancy American style packaging to increase intrigue and initial interest. There may not be a pre-established market for the product in some areas, but diversification is never a bad idea in the smaller economies where yam production is prevalent (Rubatzky & Yamaguchi, 2012). Theoretically the product would expand on farmer opportunities, ultimately having a positive impact on the community.
Yam flour
Lastly, another essential value addition could be the expanded production of yam flour. Similar to the initial process of creating the chips, the first post-harvest step would be to chop the yam into thin slices, and then mill those slices into a thick flour - one with a different sensory quality than that of a normal pounded or mashed yam (Akissoé, 2003). This would allow for the simultaneous production of both products with relative ease, expanding a farmer’s inventory. The expansion of inventory is a key aspect of the yam’s future. The key aspect of this product would have to be that the yams are dried before they are milled, due to the yam’s “high moisture content and the seasonal nature of their production (Akissoé, 2003)”. This drying leads to a decrease in swelling and solubility during pasting and subsequently to a lower past viscosity (Akissoé, 2003). Essentially, in order to produce the appropriate texture and taste of the starchy substance, the tuber must first be dried. Without the drying process the entire concept of a flour like substance disappears. Despite the longer processing time required, drying increases the product’s shelf life. The flour could be mixed with a number of dishes, serving as a substitute for general wheat flour. Similar to the yam jam, the finished product would then be much easier to transport and store then the actual hard crop itself, and could either be bagged, or placed into solid containers to be sold and distributed. The product ideally would flourish at local markets and urban grocery stores due to its diverse range of uses. In many developing countries “amala”, a delicious thick paste in which the essential ingredient is yam flour, is already very popular (Akissoé, 2003). Therefore, some consumers may have already experienced the product and it would be easier for the local culture to accept. With a pre-established demand, the product would also be able to counter-act the issue of preservation as goods would move quickly. The fact that this product requires little technological advancement, simple tools to produce, and could be easily accepted in local markets, makes it an excellent fit for smallholder farmers.
Conclusion
To conclude, the yam is a thick starchy crop loaded with essential nutrients like carbohydrates, that can be used for a wide variety of dishes. Each of these value additions has been designed to accommodate that fact, with preparation, storage, and transportation all relatively simple, and plausible for the majority of subsistence farmers. The goal of these products is to continue to expand the use of this crop, as it will maximize farmer profits, ultimately improving the livelihoods of subsistence farmers.
Useful links and practical resources
References
1. Akissoé, N., Hounhouigan, J., Mestres, C., & Nago, M. (2003). How blanching and drying affect the colour and functional characteristics of yam (Dioscorea cayenensis-rotundata) flour. Food Chemistry,82(2), 257-264. doi:10.1016/s0308-8146(02)00546-0
2. Burton, W. G., & Wigginton, M. J. (1970). The effect of a film of water upon the oxygen status of a potato tuber. Potato Research,13(3), 180-186. doi:10.1007/bf02355973
3. Girma, G., Spillane, C., & Gedil, M. (2015). DNA barcoding of the main cultivated yams and selected wild species in the genus Dioscorea. Journal of Systematics and Evolution,54(3), 228-237. doi:10.1111/jse.12183
4. Hsu, C. (2003). Chemical composition, physical properties, and antioxidant activities of yam flours as affected by different drying methods. Food Chemistry,83(1), 85-92. doi:10.1016/s0308-8146(03)00053-0
5. Rubatzky, V., & Yamaguchi, M. (2012). World Vegetables Principles, Production and Nutritive Values (2nd ed.). Springer Verlag, Berlin.
6. Swinton, S. M. (1988). Drought survival tactics of subsistence farmers in Niger. Human Ecology,16(2), 123-144. doi:10.1007/bf00888089
7. Verter, N., & Becvarova, V. (2014). Yam production as pillar of food security in logo local government area of Benue State, Nigeria. European Scientific Journal,10(31). Retrieved October 02, 2018, from https://eujournal.org/index.php/esj/index.
8. Wanasundera, J. P., & Ravindran, G. (1994). Nutritional assessment of yam (Dioscorea alata) tubers. Plant Foods for Human Nutrition,46(1), 33-39. doi:10.1007/bf01088459