Existing technologies for Sweet Potato

Existing post-harvest processing practices for Sweet Potato

Traditional processes have evolved over the years that yield a higher quality of crop for industrial and domestic uses. Some of the usual methods being practice in many areas due to low cost and ease management are washing of roots using bare hands in running water and drying under the sun or field drying.

Sweet potato roots are bulky and perishable unless cured. This limits the distance over which sweet potato can be transported economically. It was established that in cases where countries are capable of generating a surplus, it tends to be relatively localized but dispersed and this leads to a lack of market integration and limits market size (Katan and De Roos, 2004; FAO, 2011). It was reported by Fellows (2000) that food processing entails combined procedures to achieve intended changes to the raw material and the processing technologies in the food industry. The processing is subdivided into two main groups:

1. Processing of foods with non-thermal methods (Lebovka et al., 2004, 2007) such as high-pressure processing, pulsed electric field (PEF), electronic beams, and

2. Processing of foods with the application of heat (Yadav et al., 2006; Leeratanarak et al., 2006; Ahmed et al., 2010; Fernando et al., 2011; Singh and Pandey, 2012) such as blanching, pasteurization, sterilization, evaporation or concentration, drying or dehydration, microwave, and infra-red heating.

Processing by application of heat that can be used in product development from sweet potato can be carried out using four methods including:

1. Heat processing with the use of hot air e.g. dehydration, baking, roasting (Ahmed et al., 2010; Doymaz, 2012).

2. Heat processing with the use of water or steam e.g. blanching, pasteurization (Fernando et al., 2011).

3. Heat processing with the use of hot oils e.g. frying (Troncoso et al., 2009).

4. Heat processing using radiated and direct energy e.g. ohmic heating, dielectric heating, infrared heating (Zhong and Lima, 2003; Brinley et al., 2008; Wang et al., 2010).

The research in sweet potato processing has established the fact that there is a lot more in sweet potatoes than starch. Available evidence suggests that postharvest processing and subsequent storage of sweet potatoes need further research to explore the ways by which the new cultivars could be used for industrial and export purposes in countries producing sweet potato. Based on this review, future studies of the combined effects of blanching and/or freezing pre-treatments with higher drying temperature, determination of moisture diffusivity, and activation energy during different drying conditions are recommended. (OKE and WORKNEH, 2013)

Root crop washer was designed by Ghuman et al. in 2014. During the testing against the laborers in the agricultural field, the machine is more efficient than the traditional approach used. The testing done was given the same quantity of harvested crops and the time taken was noted corresponding to the number of root crops washed by each of them but further modification is still needed for this washer.

Solar radiation can be highly effective and utilized for the drying of agricultural products in our environment if the proper design is carried out. With this, Gupta et al in 2017 designed and constructed a solar dryer for drying agricultural products. This was demonstrated and the solar dryer designed and constructed expressed sufficient ability to dry agricultural products most especially food items to an appreciably reduced moisture level. Apart from this, solar energy is required for its operation which is readily available in the tropics, and it is also a clean type of energy. It protects the environment and consumes cost and time spent on open sun drying of agricultural produce since it dries food items faster. The food items are also well protected in the solar dryer than in the open sun, thus reducing the case of pest and insect attack and also contamination.

Tools and equipment being used

Tools and equipment are used to make planting easier for sweet potatoes and other crops, it is also made to ensure the quality of the crop during the post-harvest and harvesting period. Below are some tools and equipment used for sweet potato.

Small-scale growers lacking access to tractors with middle-busters or hillers can make planting ridges using hiller/furrower attachments on their rototillers or walk-behind tractors. Wheel hoes can also be an alternative tractor or rototiller implements to use, with the proper implements, it can make modest-but-adequate ridges

Sweet potato slips are hardy. Some growers simply drop them on the ground and push the rooting end into the soil with a stick. Methods such as this eliminate stooping. A transplanter is a well-constructed tool. Using a belt-pouch or pocket to carry slips, one person can do the transplanting task alone, without stooping. However, it is better-suited to two-person operation— one person handling the transplanter; one dropping the slips into the chute, and covering the roots.

Such non-motorized hand tools also easily dodge around vines that are growing into the inter-row area. In three seasons of sweet potato trials, cultivation was done with a wheel hoe, followed later by a light hoeing and a bit of hand-pulling to get a few weeds.

Plows used to dig sweet potatoes. ―The long vines must be first disposed of. They are usually pulled by running a plow on each side of the row. This work is done much more satisfactorily if the line of plants be barred off with a turn-plow, to the beam of which is attached a rolling coulter, which cuts the vines close to the row.‖ —Dugger 1911

The Yield Max Gen. II Short Digger is the ultimate machine for the harvesting of sweet potatoes and other root crops. Gentle crop handling is the result of careful design and engineering. Adjustable shakers, variable speed hydraulic driven chains, and very short end drop are but a few of its features. This machines leaves nothing in the ground, but leaves your crop gently place on top of the ground for harvesting.

This machine is the ultimate tool for grooming and maintaining plant height. The special designed housing creates a strong vacuum that lifts plants upward before cutting. Blow-down or twisting plant tops, common problems with other mowers, are completely eliminated with this mower. All plant debris is caught in a collection system; no residue falls back on the plants, thereby reducing disease problems. The collection system dumps hydraulically from the tractor seat.

This machine was designed to provide sweet potato growers an economical means to cut potato plants from the plant beds with a minimum amount of labor.

References:

• Kueper G. Small-scale Technology and Practices for Sweet Potato Growing in Southeast Oklahoma. Retrieved from https://kerrcenter.com/wp-content/uploads/2014/03/Sweet-potato-equipment-report-2014.pdf

• Oke M.O and Workneh T.S. A review on sweet potato post-harvest processing and preservation technology. Retrieved from https://academicjournals.org/article/article1381917124_Oke%20and%20Workneh.pdf