Chapters 8.29

8.29-Sweet Potato Value Addition

Alex Roberts, University of Guelph, Canada

Suggested citation for this chapter.

Roberts,A. (2022) Sweet Potato Value Addition,In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org

Introduction

Sweet potato is a widely grown root crop ( Business Diary, 2017); its large, starchy, sweet-tasting, tuberous roots compose a nutritious vegetable. The young leaves and shoots are sometimes eaten as greens (ActionAid, 2015). Over 95% of the global sweet potato crop is produced in developing countries. More than 130 million tons are produced per year, with China producing about 80% of it (ActionAid, 2015). Sweet potato is rich in carbohydrates, phosphorus, and an excellent source of Vitamins A, B and C (Business Diary, 2017). It is known to lower cholesterol with curative effects for constipation and stomach stress. Value addition from sweet potatoes has become an increasing topic in the food world today as it has endless uses and all of the plant can be used as food for humans or feed for livestock (Business Diary, 2017). Sweet potatoes are widely becoming a novel root vegetable for functional foods, as it is nutritious and widely accessible (Sweet Potato Knowledge Portal, 2018). Functional foods are described as foods that contribute to an overall healthy body (Sweet Potato Knowledge Portal, 2018).

Wrapping

The simplest value addition ideas would be to wrap sweet potatoes in newspaper in order to limit their exposure to light. Light can accelerate the autooxidation of fats and oils. This is imperative to increase shelf life, as well it can be more attractive to buyers; this can be advertised as offering a longer shelf life then other competitors (FoodSafetySite, 2012). Not wrapping each in their own individual package can lead to mold and harmful bacteria that can age sweet potatoes (FoodSafetySite, 2012). And wrapping each in an individual package would prevent pathogen cross-contamination (Lerner, B. Rosie, 2018). This process can be done extremely fast by hand and would result in a prolonged shelf life. Wrapping may be more expensive and time consuming, however, buying used newspaper or books can be inexpensive. Recycling can also lead to a cleaner environment; this can benefit smallholder farmers who sell what they produce (Knott, S., 2018). However, there is insufficient data on the price difference for wrapped compared to unwrapped sweet potatoes.

Labeling

Value addition could be achieved simply by noting the nutrient benefits of processed sweet potato on packaging. For example, baking the potatoes instead of frying or boiling allows for more nutrients to be kept (Dincer, Cuneyt, et al., 2011). Baking a potato only requires cutting then placing onto a sheet in an oven. Labeling can improve sale value/rate, while adding a quick recipe (like baked fries) could add further value. Also, including the nutritional value of sweet potatoes can be beneficial (Sustain, 2007). A study from Miller & Cassady (2015) supports the claim that including nutritious information helps increase the sale of products by increasing the rate of sales, since ‘knowledge-is-power’. This would be best sold to tourists or at markets.

Flour

Sweet potato root can be used to produce a variety of flours, which would be subsequently used to make breads, pastries and noodles (CIP, 2018). The process of producing flour from sweet potato root is described in full below. The following diagram shows an overview of the process:

The process requires a knife for cutting as well as a mill; mills can be priced as low as $60. A visual step by step process of making flour can be found at https://www.youtube.com/watch?v=GLEbnNnXqMA. This video is particularly useful because it describes the process in Kenya. Sweet potato flour can be used to fortify other flours or to make bread itself. Fortifying other flours with sweet potato flour yielded the best results compared to other white breads made from wheat flour alone (Shan, Shan, et al., 2012). Hence the packaging could advertise that sweet potato fortified bread is healthier and contains more nutrients than traditional flours. Sweet potato flour is sold in Canada at Walmart (https://www.walmart.com/c/kp/potato-flour) for $17.86/Kg, thus a smallholder farmer can mill the roots and sell for a profit.

Jam

Sweet potato today can be used to make jams with only a blender (Business Diary, 2017), which the online retailer “Alibaba.com” sells for as little as $11. Blended sweet potato can also lead to value added products such as smoothies, drinks and catsup (Business Diary, 2017). This would help improve sales at road sides and markets.

Sweet potato skins

Farmers and consumers can use the whole tuber to maximize profits. As already noted, the root can be used to create flour for human consumption or can be sold as livestock feed ( CIP, 2018). The outer layer of the tuber, instead of being thrown away, contains many useful nutrients and protein which could be added to smoothies, jams, or drinks (Allrecipes, 2018). As stated before a blender can cost as low as $11 on Alibaba.com. Additionally, sweet potato skins can also be baked (Allrecipes, 2018).

Baked sweet potatoes

There is another popular value addition from sweet potatoes which serves as a healthy alternative to white fleshed potatoes. Sweet potatoes (baked, fried, boiled) are considered as a novel source for natural health promoting compounds (beta-carotene and anthocyanins) for the functional food market (Bovell et al., 2017). Boiling sweet potatoes result in a loss in carotenoids and other important vitamins and minerals (Gehse, Saskia, et al.), hence baking is an alternative. Baking is done in an oven, which can cost as little as $60 on Alibaba, or using rocks or clay. For the latter, a tutorial can be found at https://www.youtube.com/watch?v=z_OUaJVHnF0. Baking opens up new markets, such as to tourists or at local markets.

In conclusion, there is an abundance of value addition ideas for sweet potato smallholder farmers, and there are still more to be discovered with research. Most of these products are realistic for smallholder farmers to implement.

References

1. ActionAid. (2015). What is a small holder farmer? Retrieved from http://actionaid.org/australia/2015/06/smallholderfarmers101

2. Bovell, B. Adelia C. (2007) Sweet Potato: A Review of Its Past, Present, and Future Role in Human Nutrition. Advances in Food and Nutrition Research, 7, 1–59, doi:10.1016/s1043-4526(06)52001-7.

3. Describe the different ways that food spoils. (2012). Retrieved from http://www.foodsafetysite.com/educators/competencies/general/microbiology/mic6.html

4. Dincer, Cuneyt, et al. (2011) Effects of Baking and Boiling on the Nutritional and Antioxidant Properties of Sweet Potato [Ipomoea Batatas (L.) Lam.] Cultivars. Plant Foods for Human Nutrition, 66 (4), 341-347. doi:10.1007/s11130-011-0262-0.

5. Gehse, Saskia, et al. (2018) Determination of the Effect of Boiling on the Bioavailability of Carotenoids in Vegetables Using Resonance Raman Spectroscopy. Laser Physics, 28(10), 105602. doi:10.1088/1555-6611/aad1b4.

6. Knott, S. (2018, March 22). One of Africa's most promising cities has a trash problem. Retrieved from https://qz.com/africa/1229079/ghana-the-worlds-fastest-growing-economy-has-a-trash-problem/

7. Sweet Potato Knowledge Portal, www.sweetpotatoknowledge.org/files/presentation-12-low-cost-technologies-value-addition-orange-fleshed-sweetpotato-smallholder-farmers-western-kenya/.

8. Lerner, B. Rosie. “Time to Harvest Sweet Potatoes.” Purdue Extension - Purdue University, 21 Sept. 2018, http://extension.purdue.edu/article/30787.

9. Miller, L. M., & Cassady, D. L. (2015). The effects of nutrition knowledge on food label use. A review of the literature. Appetite, 92, 207-216. doi:10.1016/j.appet.2015.05.029

10. Obi, L. “15 Ways You Can Add Value to Potatoes for More Money.” Daily Nation, 30 Sept. 2016, www.nation.co.ke/business/seedsofgold/ways-you-can-add-value-to-potatoes-for-more-money/2301238-3400418-e4g4ul/index.html. (cite as Obi, 2016)

11. Old Farmer's Almanac. (2018). Growing Sweet Potatoes. Retrieved November 29, 2018, from https://www.almanac.com/plant/sweet-potatoes

12. Shan, S., et al. (2012) Physicochemical Properties And Salted Noodle-Making Quality Of Purple Sweet Potato Flour And Wheat Flour Blends. Journal of Food Processing and Preservation, 37 (5) 709-716, doi:10.1111/j.1745-4549.2012.00686.x.

13. Sustain (2007). How can improved food labelling contribute to a healthy and sustainable food system? Retrieved from https://www.sustainweb.org/publications/how_can_improved_food_labelling_contribute/

14. “Sweet Potato Recipes.” Allrecipes, www.allrecipes.com/recipes/1094/fruits-and-vegetables/vegetables/sweet-potato/.

15. “Sweet Potato Processing and Uses.” International Potato Center (CIP), cipotato.org/crops/sweetpotato/sweet-potato-processing-and-uses/.

16. “Value-Added Products from Sweet Potato.” Business Diary PH, Business Diary Ph, 8 Dec. 2017, businessdiary.com.ph/6427/value-added-products-sweet-potato/.

17. Victoria Grain Mill - Corona Style. (n.d.). Retrieved from https://torontobrewing.ca/products/victoria-grain-mill-corona-style?variant=32012717379&utm_campaign=gs-2018-10-07&utm_source=google&utm_medium=smart_campaign&gclid=Cj0KCQiA8_PfBRC3ARIsAOzJ2uofbhQoD5PPMrJmemx2diMDGAHWGcxHijD9bGs-mKJ4GkNSNI9sHm8aAkNGEALw_wcB