Program 6

The Potential of Root Crop Processing for Rural Development in Vietnam
G. Prain¹, C. Wheatley², and Nguyen Doy Duc³

Role of Root Crops in Pig Raising
Starch and Noodles: Prospects for Sweetpotato
Conclusions and Opportunities

Vietnam is a leading world producer of sweetpotato (Ipomoea batatas) and cassava (Manihot spp.), and is probably the global leader in area planted to edible canna (Canna edulis). Historically, these crops were important seasonal, supplemental, and emergency food sources, but in the past 15 years, they have begun to assume greater importance as raw materials for value-added processing. Feed and starch are the dominant intermediate processed products. Pork, transparent noodles, candies, and baked goods are common end products. The expanded processing activity has been almost exclusively based on household initiative.

Since the mid-1980s, however, public-sector research agencies have been working to introduce the processing innovations that were developed in villages around Hanoi to other parts of the country. The mixed results from those efforts led CIP and several international and national research partners to begin an assessment, in 1995-96, of current use of root crops in four key sites in north and central Vietnam (Figure 1). The sites were in Bac Thai, Hatay, and Thanh Hoa Provinces in the north, and Quang Nam Da Nang Province in central Vietnam.

 

Sweetpotato and cassava are the two main root crops grown in farming systems in north and central Vietnam. Edible canna is less important, but was included in the study because of its Andean root crop ancestry and its importance in noodle making.

The majority of farm households in the provinces under study depend on crop-livestock systems to secure a rice-based food supply for the household as well as cash income. Both food and cash depend on an adequate supply of manure for the crops and an adequate supply of feed for the animals. When processing is undertaken for additional income, it provides a further supply of feed in the form of by-product, but it increases demand for raw material.

In Thanh Hoa Province, fresh consumption of sweetpotato by producer households declined from around two-thirds to one-third of total production from 1980 to 1994. A similar decline is also evident in cassava, but the change of function of these two crops has been different. Whereas the primary function of sweetpotato has shifted from household food to household animal feed, cassava has become a cash crop. It is grown primarily as raw material for the growing processing industry, but the processing by-product finds a ready market as animal feed.

Sown area and production trends for cassava over the past ten years show a gradual downward trend throughout the period in all four provinces (Figure 2). The abrupt decline in cassava in Hatay, which is close to Hanoi, can be attributed to a switch to sweetpotato by some farmers and a move from cultivation to more lucrative food processing and nonfarm enterprises. A strong upward trend in sweetpotato began around 1990, especially in Hatay and Thanh Hoa, where it is increasingly cultivated for pig feed.

 

Role of Root Crops in Pig Raising

From 1985 to 1995, pig liveweight in the north rose from 299,000 t to 580,000 t; per capita pork consumption more than doubled. The massive increase in sweetpotato area in Hatay, from 5,000 ha to more than 20,000 ha between 1990 and 1993, is directly attributable to the use of sweetpotato for feed.

Pig-raising systems
Two household-based pig-raising systems prevail with different implications for pig feed research. In one system, piglets are fattened for slaughter. Many households combine these systems (Table 1).

 

In Da Nang, households commonly concentrate only on breeding piglets, partly because of better access to the piglet markets of southern Vietnam and Laos. Fattening is the more common practice, especially in the more remote, poorer areas of the north. In Bac Thai, for example, there is an average of three fattening pigs per household, whereas only one in four families has a breeding sow. In high mountain areas of Bac Thai, Thanh Hoa, and Da Nang, cattle are more common domestic animals, mainly because of the availability of open pasture.

There is considerable variation in the numbers of pigs managed by different households (Figure 3), which is an important consideration in technical intervention. Families fattening only one pig are least likely to be interested in innovations. With more pigs, improved performance becomes commercially attractive.

Da Nang again stands out as different from the other sites. Not only do many households have two or more breeding sows, many more households are fattening only one piglet. That suggests the low priority and noncommercial character of fattening in Da Nang.

Bac Thai and Hatay have similar numbers of households engaged in fattening. Both appear to have greater commercial pig-raising than Thanh Hoa. In Hatay and in Thanh Hoa, of households fattening more than four pigs, only five have more than 10 head, and of those the largest operation has 40 head. These are the only large-scale pig-raising enterprises encountered, emphasizing the backyard character of most pig-raising.

Feed regimes
The two most notable findings about swine feed regimes are (1) the dominance of sweetpotato vines over roots, and (2) the limited use of protein-rich supplements, even in coastal areas where fish by-products are relatively cheap.

Vines are the most important component of pig diets in 7 out of 12 pig-rearing households in Bac Thai. In one case, vines accounted for 45% of the approximately 2.4 t of feed given to a single animal over a 12-mo growing period.

Cassava is the most important feed component in mountain households. In Hatay, the by-product from starch-processing villages accounts for up to 80% of total feed, in combination with root crops. A large part of the root crop component, however, is vines rather than roots.

On the coastal plain of Thanh Hoa, sweetpotato roots, both fresh and dried, are much more important as feed than at other sites. This is an area with as many as three harvests of sweetpotato per year and where storage of dried sweetpotato chips is relatively common. Sweetpotato vines are also important as feed.

The feed regime also varies in Da Nang. In the plains, 75% of feed consists of sweetpotato vines and small roots, whereas at higher elevations cassava by-product dominates, although sweetpotato vines still account for about 30% of total feed. Vines dominate over roots in Da Nang because of the concentration of households maintaining sows to produce piglets. Fresh or dried vines, cooked with other vegetative by-products, provide a better diet for piglets than roots.

Socioeconomic importance of pig-raising
In the plains of Bac Thai and in the Red River Delta, pig-raising contributed on average about 40% of income in case households in 1995, ranging from as little as 15% to as high as 64%. However, the purpose of pig-raising in Bac Thai is not primarily to generate direct income. Pig-fattening offers a way to convert nonfood farm output into manure and marketable pork using surplus labor¾that of the elderly, the young, and the limited spare time of women.

Households that keep breeding sows follow a different strategy. For instance, in Da Nang farmers seek to reduce feed costs and use of nonfood farm output, and to reduce the risk of disease, by selling off piglets early. This system tends to generate less manure for the crop operation. This profit-oriented but risk-averse approach works well in the special circumstances of Da Nang, with its good links to piglet markets.

The highest profits were made by families that had combined breeding and fattening pig operations, and by those with the most animals.

Constraints and opportunities
Pig fattening and piglet breeding pose different constraints and offer different opportunities for intervention in root crop-based feed. Households involved in multiple pig-fattening are interested in increasing the volume of feedstuffs produced on-farm, feed conversion characteristics of their animals, and the rate of weight gain. In Thanh Hoa, the farrow-to-finish time ranges from 6 to 12 mo. The difference is largely due to diet, both the volume of feed and the inclusion of protein-rich supplements. There are clearly opportunities here for exploring improved vine and root productivity and for evaluating alternative feed regimes.

Starch and Noodles: Prospects for Sweetpotato

Starch production in north and central Vietnam
Major sources. The two major sources of starch in north and central Vietnam are cassava and canna; sweetpotato is only a minor starch source at present. Cassava is by far the largest and cheapest source and small-scale processing occurs in most provinces (Table 2). Canna starch processing occurs on a smaller scale, primarily for the specialty production of transparent noodles. Canna starch enterprises were found in a few villages in Bac Thai and Thanh Hoa close to areas where the root was grown; canna processing is not done in Da Nang. In northern Vietnam, most cassava and canna starch production is concentrated in five villages in Hoai Duc District, Hatay Province, near Hanoi. A total of 5,679 households were processing cassava starch in 1995, consuming between 100,000 and 200,000 t of roots to produce around 50,000 t of starch. In the same area, 276 households processed about 34,000 t of canna into 7,500 t of starch in 1995.

Processing efficiency. The procedures to extract starch from cassava, canna, and sweetpotato are simple and cheap. Roots are washed (cassava roots are peeled first to prevent starch discoloration), grated, and filtered through cloth into a concrete container of water to make a slurry. The slurry is filtered four times and then allowed to settle for 6 h (longer in winter). The water is drained, leaving wet starch of 35-45% moisture content.

From 100 kg of cassava roots, about 42 kg wet starch can be extracted, yielding about 28 kg dry starch. Canna roots convert to 28-30 kg wet starch from 100 kg fresh wt, yielding 21-23 kg dry starch. Sweetpotato has the lowest extraction rate, yielding 25-30 kg wet starch or 17-20 kg dry starch from 100 kg fresh wt, depending on variety and time of year.

Cassava processing benefits. Producers of fresh cassava and canna and a variety of assembler and transport businesses supply the roots over long distances for sale to starch processors in Hoai Duc.

The concentration of processing households in one area in Hatay increases the efficiency of transportation, making it feasible to truck in fresh roots from up to 320 km away. It also facilitates the specialization of processing activities among households and the exchange of products and services. The large volume of final products generated enters a complex marketing system of processed products throughout north and central Vietnam. Consignment arrangements are common in this system between processors and traders.

Costs and benefits vary greatly among the cassava processors studied. Hatay processors have high transportation costs, which increases the price of the roots. But that is partly compensated for with higher processing efficiency. The profitability in Bac Thai is due to a higher selling price for wet starch of US$0.16/kg, compared with between $0.12 and $0.13/kg at the other sites, and a much higher valued by-product. Though profitability is quite low for cassava starch processors, it represents about 60% of annual income for some households. In Thanh Hoa, the processing season runs from October to March. Average processing during the season for the case households is about 30 t of fresh roots, which yields just under $400 income.

Sweetpotato could be an alternative source of bulk starch in the north. At present there is almost double the quantity of raw material available (1.8 million t compared with 1 million t of cassava). However, the low starch extraction rate of sweetpotato makes cassava ultimately a cheaper raw material.

Transparent noodle supply and demand
Per capita noodle consumption in Vietnam in the early 1990s was 12-20 kg; transparent noodle may represent 10-15% of that. The most common raw material for transparent noodle over the past 30 yr has been canna root.

Canna starch and noodle processing is undertaken on a small scale in Bac Thai and Thanh Hoa, but the major production area is the same intensive processing district of Hoai Duc, Hatay. Unlike cassava-based processing, with its clear division of labor between starch producers and maltose processors, canna starch and noodle processing is often combined. Of the 276 starch-producing households in Hatay, 230 also produce noodles using their own starch.

The long growth duration of canna, usually from March to November, means that the processing season is quite short, generally from November to March or April. Although this covers the period of the Vietnamese New Year when noodles are most in demand, it limits the opportunities for optimizing investment at other times of the year.

In Bac Thai, where up to a ton of fresh roots can be processed in a day, average net profits of case households were around $16/d (Table 3). This compares to around $1/d for agricultural laborers. The bulk of starch and noodle demand is met from Hatay, thus inflating the costs of the final product in areas beyond Hanoi. The lower profitability of starch from Hatay reflects both the more expensive raw material, trucked in over large distances, and a lower starch price.

Noodle processing clearly offers the highest returns of the processing activities studied (Table 4). The net benefit recorded in Thanh Hoa may be overestimated. Unlike the other calculations, the Thanh Hoa calculation failed to include depreciation and underestimated costs for fuel and other inputs. The relatively low profitability of noodle production in Bac Thai is caused by a much lower conversion rate from starch to noodle, which is due to a different and less efficient processing technology that uses manual extrusion rather than steaming.

Table 4.

Coast and benefitsa of processing 100 kg of canna starch into transparent noodleb in three provinces, Vietnam, 1995.

The potential of sweetpotato starch in noodle enterprises
The relatively narrow adaptation of canna at high altitudes, its remoteness from processing areas, and the long growing season mean that the supply of raw material is limited to a few months. But the period of raw material supply coincides with the period of highest demand for the starch, leading up to the New Year celebrations. Therefore, prices remain high, even during this glut period.

These raw material supply problems, however, have resulted in very little exploration of sweetpotato as an alternative. This is despite the proximity and stable supply of the crop—there are three harvests a year in some areas—and the limited fresh root market for sweetpotato, which frequently results in depressed prices.

The reluctance has been due to technical and cultural factors. Sweetpotato has a lower starch content than canna and the extracted starch has a grayish color. The noodles made from the starch also tend to be more brittle. Sweetpotato is also perceived as a food and feed crop, not an industrial raw material.

Technology development and participatory pilot studies in Hatay and Thanh Hoa Provinces have shown that it is technically feasible and profitable to use sweetpotato starch in transparent noodles. Using lime during starch filtration improves separation and yields a whiter starch. And combining canna starch with sweetpotato starch overcomes the brittleness of 100% sweetpotato.

Using sweetpotato starch, however, involves more work and processors require a lower price for sweetpotato starch to justify the extra effort. In addition, the supply of sweetpotato starch remains a problem and is not yet stable.

In 1996, pilot work on starch production, begun earlier in a southern district of Thanh Hoa Province, transferred to Hoang Hoa, nearer the provincial capital. Twelve households have enthusiastically adopted sweetpotato and canna starch production, first to supply noodle processors in Thanh Hoa City, and more recently to produce noodles themselves. Almost all of the sweetpotato/canna noodle produced so far has been marketed and priced as canna noodle. In focus group discussions with a stratified sample of consumers in Hanoi during 1995, high-income consumers reacted negatively to sweetpotato as a raw material. But medium- and low-income consumers, who were more concerned with noodle quality than sweetpotato’s image, gave a positive evaluation.

Conclusions and Opportunities

The enormous opportunities for economic development in Vietnam are mostly generated at the base, among rural households. The role of agriculture is increased productivity, of course, in addition to value-added products made available through processing. The processing of root crops for pig feed, starch, and noodles is an important part of that processing potential.

As a result of the appraisal of the use of root crops for pig feed, starch, and noodles, two projects have been established. The first project involves:

• evaluating genetic material for high foliage production and high protein content for use in pig-fattening enterprises,
• evaluating genetic material for high dry matter,
• assessing the use and costs of available protein supplements to energy-based sweetpotato and other feed, and
• exploring alternative ways of preparing feed to improve digestibility and quality.

The second project aims to improve the efficiency of sweetpotato and canna for starch and noodle processing. It involves:

• supporting pilot units for sweetpotato starch and noodle production,
• evaluating new sweetpotato cultivars for potential in starch processing,
• evaluating new canna varieties for use in starch and noodle production, and
• supporting improved marketing linkages between starch producers and noodle producers.

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1 CIP, Los Baños, Philippines.
2 CIP, Bogor, Indonesia.
3 Post Harvest Technology Institute, Hanoi, Vietnam.