Báo cáo khoa học nông nghiệp " Commercial and High Quality Cultivars of Root and Tuber Crops for Processing Purpose in the Northern and Central Vietnam " MS7 potx
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Ministry of Agriculture & Rural Development Collaboration for Agriculture & Rural Development 008/07VIE CommercialandHighQualityCultivarsofRootandTuberCropsforProcessingPurposeintheNorthernandCentralVietnam Vietnamese Institution Food Crops Research Institute, Ministry of Agriculture and Rural Development Vietnamese Project Team Leader Assoc. Prof. Dr. Nguyen Van Tuat Australian Institution Faculty of Agriculture, Food and Natural Resources, University of Sydney Australian Project Team Leader Professor Les Copeland Outputs 3 and 4 MS7: Sweet potato processing Preparation of animal feed from sweet potato leaves, vines and roots Extraction of starch from sweet potato May - 2010 1 I. Introduction Sweet potato 1 (Ipomea batatas, a member ofthe Convolvulacae family), is grown in over 100 countries, mostly by small holder farmers. It has a high yield potential for biomass production, is adapted to a wide range of habitats and soils, and ranks among the world’s top ten food crops on production volume. Sweet potato is a versatile crop. The roots are eaten as vegetables or are processed for diverse uses including making noodles and snack foods, fermentation into alcoholic beverages, and production of starch. The roots are a good source of edible energy inthe form of starch, and also provide a source of dietary fibre from non- starch polysaccharides. Sweet potato leaves are rich in vitamins A and C and have relatively high protein content (25–30% of dry matter) compared to other leafy vegetables. The carotene and anthocyanin pigments, which are responsible forthe yellow, orange, red, or purple flesh colours ofthe roots, are a source of natural pigments forthe food industry. The roots, leaves and vines are used for livestock feeding, as fresh or dried material, or after fermentation into silage. Fresh sweet potato roots normally contain between 20 and 50% dry matter, depending on cultivar and developmental stage ofthe plant at harvest. Carbohydrates make up about 90% of dry matter, most of which is starch. The sweetness is due to sugars, mainly maltose but also sucrose, glucose and fructose, which can account for between 5 and 30% ofthe dry matter. The other major components are non-starch polysaccharides (0.5-7.5%), protein (1-10%) and lipids (1-2%). The composition ofthe roots varies depending on cultivar, environment for crop growth, cultivation practices, postharvest storage, and influences nutritional, qualityand taste/texture properties. Sweet potato roots deteriorate inprocessingand nutritional quality within about 2-3 weeks after harvest, with loss of moisture and starch content and increase in sugars. Microbial spoilage, particularly in damaged roots, and sprouting are other potential postharvest problems. Processing is an important way of preserving the value ofthe large amount of biomass produced by sweet potato plants that can not be used by farmers inthe short time before postharvest deterioration becomes significant. The overall goals ofthe project are to improve yield and economic return from sweet potato production in Thanh Hoa, Bac Giang and Quang Tri provinces ofVietnam by - encouraging adoption of improved cultivarsand planting materials - providing farmers with greater options for value adding - Enhancing skills of scientists, extension officers and farmers. The specific objectives addressed in this section ofthe project are to demonstrate simple proof-of-concept methods for i. fermenting sweet potato leaves, vines and roots into a silage-type product for animal feeding, and showing how the process may be adopted by small-holder farmers ii. Large scale extraction of starch from sweet potato roots. 1 Recommendedusagetodifferentiatesweetpotatofromthepotato(Solanumtuberosa),whichbelongstothe Solanaceae. 2 Preparation of animal feed from sweet potato leaves, vines and roots In this section ofthe project, a simple and efficient method was developed forprocessing sweet potato vines, leaves and roots into livestock feed. The method was demonstrated to local farmers in Bac Giang, Thanh Hoa and Quang Tri provinces. The biological energy ofthe sweet potato biomass may be conserved, andthe consumption time for animal feed prolonged, by microbially fermenting the leaves, vine and roots under anaerobic conditions. Anaerobic conditions have to be maintained subsequently during storage to prevent spoilage ofthe material due to putrefaction. As described subsequently, salt and a source of energy (cassava starch, rice bran or corn flour) are added to the sweet potato biomass, as a starter for fermentation to provide the right conditions for rapid growth ofthe appropriate microorganisms. Research scope - Produce livestock feed in Bac Giang, Thanh Hoa and Quang Tri - Demonstrate the benefits to farmers from using the fermented vine-leaves and roots of sweet potatoes. - Solve technical challenges for fermentation processingand usage ofthe livestock feed. II. Aims The specific aims were to demonstrate technology that could be used to - preserve sweet potato roots from microbial spoilage and vermin and thereby prolong the shelf life of feed for pigs and cattle - improve the digestibility and nutritional qualityofthe feed by stimulating the production of organic acids such as lactic and acetic acids and amino acids from the biomass - Improve the organizational efficiency of farms by saving energy and labour in preparing feed for livestock and by processingthe large volume of sweet potato biomass in a timely manner after harvest and before the next crop. - Increase economic efficiency of livestock growing by utilising all ofthe sweet potato biomass, including roots unsuitable for human use because they are too small or large, or damaged. III. Methods 3.1. Locations In Bac Giang province: - Bich Son ward in Viet Yen town - Ngoc Chau ward in Tan Yen town - Mai Trung ward in Hiep Hoa town In Thanh Hoa province: - Nguyen Binh ward in Tinh Gia town - Quang Luu in Quang Xuong town 3 - Dong Thanh ward in Dong Son town In Quang Tri province - Vinh Thai ward in Vinh Linh town - Gio Hai ward in Gio Linh town - Hai Quy ward in Hai Lang town 3.2 Ingredients for preparing livestock feed - Sweet potato leaves, vines and roots, sliced and dried under the sun until tender. - Dried rice bran or corn bran or corn flour. - Salt. 3.3 Technology transfer methods - Train and transfer to farmers the techniques to use vine-leaves and roots of sweet potatoes - Design experiments to assess theprocessing by fermentation ofthe sweet potato biomass in 15 households inthe 3 towns of each province in order to recommend these processes to other households. - Prepare different ingredients for fermentation processes ofthe sweet potato biomass: o Forthe sweet potato vine and leaves 90% wilted vine-leaves + 10% rice bran + 0.5% salt 97.5% wilted vine-leaves + 2.5% sugar cane molasses + 0.5% salt 94% fresh vine-leaves + 6% corn flour + 0.5% salt o Forthe sweet potato roots 10% root + 89.5% fresh vine-leaves + 0.5% salt 25% root + 75% fresh vine-leaves + 0.5% salt 50% root + 50% fresh vine-leaves + 0.5% salt (Note: the starch inthe sweet potato roots serves as the energy source and hence sugar, molasses, corn starch, etc., do not have to be added as well) - Instruct the households on the techniques for fermenting sweet potato biomass. The fermentation period to achieve a stable pH was about 2 weeks for sliced-vine-leaves and 3 weeks for sliced-roots. - Show farmers how to preserve the fermented products; if the products are kept in anaerobic conditions created by the air-tight enclosure in plastic, the shelf-life will be extended for up to 6 months without reducing safety and nutrition. - Guide the farmers how to use and mix the fermented feeds with the other materials for pigs with different weight. Pigs of 2.5 months or 18 to 20 kg are able to eat the fermented feed. Inthe first two days, the pigs should consume 2 meals per day with the mixture ofthe fermented mash and bran per day. Then they can be fed 3 meals per day (morning, noon and evening). 3.4 Participants - Food Crops Research Institute (FCRI): Nguyen Van Tuat, Truong Cong Tuyen, Nguyen Dat Thoai, Truong Thi Thuy, Nguyen Phan Anh, Tran Quoc Anh, Do Thi Lieu, and Nguyen Thi Hoai 4 - The University of Sydney: Les Copeland, Peter Sharp, Richard Trethowan IV. Research results 4.1. Livestock feed production in Bac Giang province 4.1.1. Fermentation of vine-leaves After about 60 days of growth sweet potato plants are pruned to remove roughly half ofthe foliage. At this stage the storage roots have not developed but if the vines and leaves are cut properly, the subsequent development ofthe storage roots will be enhanced. The fermentation process andthe ingredients used for vines and leaves were as recommended by the International Potato Centre (Centro Internacional de la Papa-CIP). Thequalityofthe fermented sweet potato product was evaluated by its visual appearance, consistency of texture, the presence of a sweetish, slightly acidic aroma, the absence of foul odours, and its appeal to livestock. After growing 120 days, farmers can harvest sweet potato roots and collect vine-leaves. Roots that are too small or too big roots and damaged roots can be mixed with the vines and leaves for fermentation. It was found that the fermentation process for ingredients ofthe sliced fresh vine-leaves and sliced roots were convenient, simple and gave a good qualityof fermented product. Utilisation ofthe sweet potato roots could reduce the expenditure for feeding raw materials. Good results were obtained when the experiments were carried out inthe nine locations in Bac Giang, Thanh Hoa and Quang Tri provinces. The fermentation products from the different ingredients for sweet potato vine-leaves were evaluated in Bac Giang as shown inthe Table 1. Table 1. Evaluation of fermented products of sweet potato vine-leaves in Bac Giang, years 2008-2009 Locations Bich Son-Viet Yen Ngoc Chau-Tan Yen Mai Trung-Hiep Hoa Ingredients (1-5) (1-5) (1-5) CT 1 5 5 5 5 5 4 5 5 4 5 5 3 4 4 5 CT 2 5 4 4 5 4 4 4 5 5 5 4 3 5 4 5 CT 3 5 5 5 5 4 5 5 5 5 5 5 3 4 4 4 Note: Score range 1-5: 1= very bad; 2 = bad, 3 = medium; 4= good; 5 = very good. CT1: 90% wilted vine-leaves + 10% rice bran + 0.5% salt CT2: 97.5% wilted vine-leaves + 2.5% cane molasses + 0.5% salt CT3: 94% fresh vine-leaves + 6% corn flour + 0.5% salt Table 1 showed that the fermented product had either good or very good quality with most scores of 4 and 5. All ofthe households carried out the experiments properly by following the instructions under the supervision ofthe FCRI staff. 5 Inthe wards in Viet Yen, Tan Yen and Hiep Hoa, the farmers became familiar with the fermentation technology of sweet potato vine-leaves and obtained finished products with good quality. The comprehensively described technology processes enabled farmers to apply it easily so that thequalityofthe fermentation products could not be differentiated after using the various ingredient combinations with sweet potato vine-leaves. This means the method is flexible enough for farmers to use the available ingredient materials they have for fermentation of sweet potato vine-leaves depending on the economic and market conditions at the time. 4.1.2. Fermentation of sweet potato roots Table 2. Evaluation of fermented products of sweet potato roots in Bac Giang, years 2008 – 2009 Locations Bich Son-Viet Yen Ngoc Chau-Tan Yen Mai Trung-Hiep Hoa Ingredients (1-5) (1-5) (1-5) CT 1 5 5 5 5 5 5 4 5 5 3 5 3 5 5 5 CT 2 5 5 5 5 5 5 4 5 5 3 5 3 5 5 5 CT 3 5 5 5 5 5 5 4 5 5 3 5 3 5 5 5 Note: Score range 1-5: 1= very bad; 2 = bad, 3 = medium; 4= good; 5 = very good. CT1: 10% root + 89.5% fresh vine-leaves + 0.5% salt CT2: 25% root + 75% fresh vine-leaves + 0.5% salt CT3: 50% root + 50% fresh vine-leaves + 0.5% salt As shown in Table 3, the households at Bich Son ward in Viet Yen town produced the best qualityof fermented products inthe 15 households. The lower scores of 3 in some ofthe trials in Ngoc Chau-Tan Ten and Mai Trung-Hiep Hoa were due to damage to the bags from rats and other rodents, so that some ofthe fermented material was exposed to air. Thequalityofthe fermented products in these was decreased due to spoilage by bacteria and mould growing inthe aerobic environment. 4.2. Livestock feed production in Thanh Hoa province 4.2.1. Fermentation of vine-leaves The fermented products of vine-leaves inthe three towns of Thanh Hoa were evaluated and shown inthe table 3 below. 6 Table 3. Evaluation of fermented products of sweet potato vine-leaves in Thanh Hoa, years 2008 – 2009 Locations Dong Thanh-Dong Son Quang Luu-Quang Xuong Nguyen Binh-Tinh Gia Ingredients (1-5) (1-5) (1-5) CT 1 3 4 5 5 5 4 4 5 4 5 5 5 5 5 5 CT 2 3 4 4 5 4 4 4 5 5 5 5 5 5 5 5 CT 3 3 4 5 5 4 4 4 5 5 5 5 5 5 5 5 Note: Score range 1-5: 1= very bad; 2 = bad, 3 = medium; 4= good; 5 = very good. CT1: 90% wilted vine-leaves + 10% rice bran + 0.5% salt CT2: 97.5% wilted vine-leaves + 2.5% cane molasses + 0.5% salt CT3: 94% fresh vine-leaves + 6% corn flour + 0.5% salt - The households in Nguyen Binh-Tinh Gia produced the best fermented feed quality with all scores of 5. Thequality was scored from 4 to 5 in Quang Luu and it was 3 in one household at Dong Thanh-Dong Son. - In all locations, the households followed the same processing protocol for fermentation experiments and therefore almost all ofthe products had the same good quality. The only household with a score of 3 was in Dong Thanh-Dong Son, which was due to a leaking plastic bag. - Since the ingredients for fermentation were simple andtheprocessing technologies were straight-forward, the farmers were able to produce livestock feeds with uniformly good quality. 4.2.2. Fermentation of sweet potato roots The fermentation trials of roots and vine-leaves gave many benefits because the farmers in Thanh Hoa harvested a large number of sweet potato roots in a short time. The utilization of roots was able to save input costs for farmers as an alternative to purchasing rice bran, corn flour and sugar cane molasses as a carbohydrate source to promote the growth ofthe right bacteria for good fermentation. In addition, the trails demonstrated how the farmers could save time and money by not having to buy, transport and store rice bran, corn bran or corn flour for livestock feed preparation. Moreover, consumption of unsalable sweet potato roots forthe animal feed could clear up the field efficiently and quickly. The small roots and residual vine-leaves were combined to produce fermented livestock feed as shown inthe Table 4. Table 4. Evaluation of fermentation products of sweet potato roots in Thanh Hoa, 2008-09 Locations Dong Thanh-Dong Son Quang Luu-Quang Xuong Nguyen Binh-Tinh Gia Ingredients (1-5) (1-5) (1-5) CT 1 5 5 5 5 5 5 5 5 5 4 5 5 5 5 5 CT 2 5 5 5 5 5 5 5 5 5 4 5 5 5 5 5 CT 3 5 5 5 5 5 5 5 5 5 4 5 5 5 5 5 7 Notes: Score range 1-5: 1= very bad; 2 = bad, 3 = medium; 4= good; 5 = very good. CT1: 10% root + 89.5% fresh vine-leaves + 0.5% salt CT2: 25% root + 75% fresh vine-leaves + 0.5% salt CT3: 50% root + 50% fresh vine-leaves + 0.5% salt - All ofthe households in Thanh Hoa successfully produced of fermented feed products of very good quality. - The farmers growing sweet potato as part of Project AUSAID CARD 008/07VIE was very happy to apply the fermentation technology for livestock feeds. Beside the households that participated these experiments, many others outside the project applied theroot fermentation technique for animal feed. - Based on the fermentation technology for sweet potato root with vine-leaves, the farmers inthe project will try to use sweet potato roots with vine-leaves of other plants such as pea nut and cassava. That is a good approach to utilize the biological yield for livestock feeding. 4.3. Livestock feed production in Quang Tri province 4.3.1. Fermentation of sweet potato vine-leaves Similar to Bac Giang and Thanh Hoa, the farmers in Quang Tri have a traditional method to process the livestock feed by cutting and drying the sweet potato vine-leaves. The dried vine- leaves can be preserved and used for feeding over a long time. However, the fermented feed has microbial metabolites (lactic acid, acetic acid, etc.) and biomass (amino acid, protein, etc.) providing good benefits for nutrition and digestion. In addition, the farmers in Quang Tri found that the ingredients were simple andtheprocessing process was comprehensively described to be applied. Therefore the households ofthe project in Quang Tri joined enthusiastically the fermentation technology of sweet potato vine-leaves for livestock feed. Thequalityofthe fermented products was evaluated and shown inthe table 5. Table 5. Evaluation of fermented products of sweet potato vine-leaves in Quang Tri, 2008 – 2009 Locations Vinh Thai-Vinh Linh Gio Hai-Gio Linh Hai Quy-Hai Lang Ingredients (1-5) (1-5) (1-5) CT 1 5 4 5 5 4 4 4 5 4 5 5 5 5 5 5 CT 2 5 4 4 5 4 4 4 5 4 5 5 5 5 5 5 CT 3 5 4 5 5 4 4 4 5 4 5 5 5 5 5 5 Note: Score range 1-5: 1= very bad; 2 = bad, 3 = medium; 4= good; 5 = very good. CT1: 90% wilted vine-leaves + 10% rice bran + 0.5% salt CT2: 97.5% wilted vine-leaves + 2.5% cane molasses + 0.5% salt CT3: 94% fresh vine-leaves + 6% corn flour + 0.5% salt Table 5 shows that thequalityof fermented products from vine-leave was not significantly different. 8 - The farmers in Quang Tri were very happy because they could easily source the raw materials and quickly learn the fermentation technology in order to produce good feed for rapid livestock growing. 4.3.2 Fermentation of sweet potato roots The farmers accepted the fermentation models of roots because the harvested yield left a high ratio of small roots. The models in Quang Tri province were evaluated and shown inthe table 6 below. Table 6. Evaluation of fermentation products sweet potato roots in Quang Tri, years 2008 – 2009 Locations Vinh Thai-Vinh Linh Gio Hai-Gio Linh Hai Quy-Hai Lang Ingredients (1-5) (1-5) (1-5) CT 1 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 CT 2 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 CT 3 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 Notes: Score range 1-5: 1= very bad; 2 = bad, 3 = medium; 4= good; 5 = very good. CT1: 10% root + 89.5% fresh vine-leaves + 0.5% salt CT2: 25% root + 75% fresh vine-leaves + 0.5% salt CT3: 50% root + 50% fresh vine-leaves + 0.5% salt The fermentation processes of sweet potato roots inthe three town of Quang Tri were extremely successful with the best quality, with all scores at 5. The combination of sweet potato roots and vine-leaves was useful and applicable because it brought farmers convenience and economic efficiency for livestock feeding. V. Conclusion and general comments 5.1. Economic efficiency of using fermented vine-leaves and roots The use of fermented vine-leaves and roots provided economic benefits to farmers: - Utilisation ofthe whole biomass yield of sweet potato - Significant reduction in expenditure on livestock feed livestock to increase the farmer income. At the CARD Project Forum held on 6 April 2010, representatives from the provinces concerned spoke ofthe benefits of fermenting the sweet potato foliage as a value adding process, indicating that it could reduce the amount ofthe usual feed used by up to 30-50% - Help pigs and cattle gain more weight due to the nutritional benefits ofthe fermented feed, such as high digestibility (short chain carbohydrates and organic acids) andhigh protein content (amino acid and biomass from microbial cells). - The fermentation processes are applicable at household scale because of simple ingredients and tools, and comprehensively-described procedures - Using the fermented feeds is convenient because of a long shelf life and its ready-to-feed nature for livestock. 5.2. Technical challenges forprocessingand use of fermented feed 9 - The ingredients need to be mixed well to achieve homogenous distribution of moisture and nutrients for good microbial growth - The bags need to be packed tightly to minimize the air to promote microbial growth under anaerobic conditions - Complete consumption of one bag at a time, before opening a new one. The bags should be repacked tightly after withdrawing feed, and inspected periodically to check for spoilage. VI. Appendixes 6.1 Fermentation process of sweet potato vine-leaves Step 1: Raw material preparation - Cut vine-leaves into pieces of 0.2 to 0.5cm using a kitchen knife or a special cutting tool - Wilt under the sun immediately after cutting to minimize the nutrition loss due to respiration by the fresh vine-leaves. Step 2. Ingredients preparation - After the vine-leaves are wilted, prepare the additives (rice bran, corn bran, corn flour, cassava starch and salt) as calculated and weighed according to the formula. Step 3. Mixing - Mix rice bran, corn bran, and corn flour or cassava starch with salt to make a homogeneous mixture. - Mix the additive mixture thoroughly with the cut and wilted vine-leaves Step 4. Packing - Pack the mixture tightly into a polyethylene (PE) bag enclosed in a woven polypropylene (WPP) bag. The PE layer has low oxygen permeability to create the anaerobic conditions forthe growth of fermentative bacteria. The WPP layer keeps the PE layer from breaking and tearing when the mixture is pressed tightly, transported and stored. Step 5. Storage - Keep the fermented feed in a dry, cool place to prevent damage from insects and rodents. If the bag is damaged, the feed will have a bad odour due to spoilage by bacteria and mould. The feed can be used after 2 weeks of fermentation, and has a shelf life of about 6 months under good storage conditions. 6.2. Fermentation process of sweet potato roots Step 1. Raw material preparation At harvest time inthe spring and winter season, growers have fresh vine-leaves and roots to prepare the livestock feed. Cut or slice roots to the same size ofthe cereal grain by hand or by the cutter. If using the cutter, the roots have to be pre-cut to the size fitted to the cutter intake. Step 2. Additive preparation [...]... production for starch manufacture led to a big increase inprocessing capacity There were no medium- or large-scale cassava starch factories inVietnamin 1990, whereas in 2007, there were 60 cassava processing factories with total processing capacity of 3.2 - 4.8 million tonnes of fresh roots annually In comparison, production of sweet potato roots inVietnam has for many years been between about 1.5 and. . .The producers will choose a suitable ingredient depending on many factors such as the numbers of pigs, the sweet potato crop season, thequalityand quantity of sweet potato roots and so on It is very important for them to utilize the available materials and correct additives to ferment the feed for pigs or cattle Step 3 Mixing Mix the cut vine-leaves and roots well with salt The small reject... potato roots Mixing additives with the cut vine-leaves Packing and stuffing The products after 3 weeks fermentation 11 Extraction of starch from of sweet potato roots I Introduction Starch is the main storage carbohydrate of plants and a biopolymer of considerable significance for humans Starch is deposited in plant tissues as insoluble, semi-crystalline granules, which are made up of two polymers of glucose:... pharmaceuticals and nonedible products Worldwide, 60 million tonnes/yr of starch are extracted from wheat, corn, potato, rice, cassava, sweet potato, depending on local agriculture The main source of starch for industry inVietnam is cassava roots Most ofthe industrial starch is used for food processing, as a substrate for microbial fermentation (mainly for production of monosodium glutamate), manufacture of textiles,... with the wilted cut well 6 - Packing - Packing - Stuffing - Stuffing - Tightening - Tightening 7 Record the time of fermentation, storage and Record the time of fermentation, storage and preservation 8 preservation - Use after 2 week fermentation - Use after 3 week fermentation - Tighten the bag after taking the feed - Tighten the bag after taking the feed 10 Fermentation model for livestock feed Cutting... unbranched, andthe highly branched amylopectin Starch granules vary considerably, between and within plant species, with regard to size, shape, amylose and amyl pectin content and functional properties relevant to food processingand human nutrition Starch is a macro-constituent of many foods andthe main source of energy inthe human diet How we digest starch has important health implications Diets rich in. .. (dry and cool place) 6.3 Summary of fermentation process for sweet potato vine-leaves and roots Steps Vine-leaves Roots 1 Cut and wilt vine-leaves Cut and slice fresh root 2 Weigh the wilted vine-leaves Weigh the fresh cut roots 3 Weigh additives: rice bran, or corn flour or Weigh additives: vine-leaves and salt cassava starch with salt 4 Mix additives well Mix additives well 5 Mix additives with the. .. mixture was placed in a coarse cloth bag inside a domestic 12 washing machine, which was used inthe spin cycle as a simple centrifuge to separate the starch from the fibrous root material The starch was released in a water suspension, which was collected in a large plastic tub and allowed to settle for 3 to 4 hours After settling, the supernatant was decanted from the sediment starch The starch was washed... year The area under sweet potato production is about 200,000 ha/year, with a yield of about 8 t/ha compared to the global average of 12-15 t/ha Sweet potato and cassava roots have similar dry matter content Cassava roots have lower content of reducing sugars, whereas sweet potato offers the benefit of more nutritious foliage than cassava and environmental benefits, both inthe growth ofthe crop and. .. reject size roots are used to replace rice bran, broken rice, corn flour in order to reduce the input cost for purchase of additives Step 4 Packing It is the same with the packing stage for fermentation process of vine-leaves Step 5 Storage The livestock feeds fermented from sweet potato roots are available to use after 3 weeks of fermentation Their shelf life will also be 6 months if stored in good conditions . Crops for Processing Purpose in the Northern and Central Vietnam Vietnamese Institution Food Crops Research Institute, Ministry of Agriculture and Rural Development Vietnamese Project. Ministry of Agriculture & Rural Development Collaboration for Agriculture & Rural Development 008/07VIE Commercial and High Quality Cultivars of Root and Tuber Crops for Processing. diverse uses including making noodles and snack foods, fermentation into alcoholic beverages, and production of starch. The roots are a good source of edible energy in the form of starch, and also