Cassava Starch Processing at Small Scale in North Vietnam

Abstract

In Northern Vietnam, small‐scale cassava starch processing is conducted in densely populated craft villages, where processors face difficulties to expand their activities. Three different processing systems were studied among a cluster of three communes in the Red River Delta, producing up to 430 t of starch (at 55% dry matter) per day. The first system, type A, is a cylindrical rasper and a manual sieve, the second, type B, is a cylindrical rasper and stirring‐filtering machine and the third, type C, used equipment for both the rasping and filtering stages. Moisture, starch, crude fibers and ash content analysis were carried out on samples collected from the A‐B‐C manufacturing processes to establish the mass balance of starch. Production capacity, water consumption, electrical requirements and capital‐labor costs per tonne of starch (12% moisture) were also reported. A‐B‐C manufacturing processes enabled 75% recovery of the starch present in fresh roots. No significant change was observed in the composition of starch. Upgrading from system A to B and subsequently to C resulted in an increase in the extraction capacities (up to 0.9 t of peeled roots per hour), the extraction efficiencies during the extraction stage (up to 93%), and an increase in the water consumption and electrical power (up to 21 m3 and 55 kWh per tonne of starch, respectively). The highest amount of total solids carried in the waste‐water was obtained with type C (up to 17% of the dry weight of fresh roots, compared to 10% and 13% for type A and B, respectively). This may lead to a higher chemical oxygen demand (COD) and biological oxygen demand (BOD) in waste‐water, which can result in more polluted waste‐water than compared with the type A and B technologies. Upgrading the rasping‐extraction technologies also resulted in higher profits and reduction of labor per tonne of starch (up to 18 US$ and 26 man‐hours respectively). The diagnosis proposed in this study can be applied in different contexts to recommend technological options by considering space, energy and capital‐labor availabilities.

Cassava: An appraisal of its phytochemistry and its biotechnological prospects

“…Starch production from cassava storage roots is carried out both at the cottage and industrial scales and caters for the increasing demand for starch both locally and worldwide (Da et al, 2008;Srinivas, 2007;Sriroth et al, 2000;Tonukari, 2004). High value modified starches used in food and industrial processes are conventionally produced by energy-expensive chemical means; however, there are strong arguments for them to be produced in planta (Davis et al, 2003).…”

A comparison of energy use, water use and carbon footprint of cassava starch production in Thailand, Vietnam and Colombia

“…For ST1, a survey in three craft villages of suburban Hanoi producing cassava starch (Da, 2008) indicated that the factory selected for the study was representative of 70% of the existing starch factories, in terms of type and size of equipments, power of the motors and processing capacity (1 t starch/day), while other factories used the same technology but with larger capacities (2-4 t starch/day). For ST2, the surveyed factory used the same technology as 90% of the factories operating in the Cauca department, although some equipments were larger than average because the factory had one of the highest production capacities (2 t starch/day) of the region.…”

“…) from the starch, by either hydrocyclones (VLT) or sedimentation (ST1, ST2); (6) dewatering consists in mechanical removal of water by centrifugation (VLT) or sedimentation (ST1, ST2), to reach a moisture content of 33-45% wwb; (7) drying consists in drying the starch to the final moisture of 12-13% wwb, to inhibit microbial growth and ensure an extended shelf life. In some cases (ST1), the drying operation may be skipped due to limiting factors such as energy costs, and the starch preserved under wet conditions (45% moisture) through a lactic fermentation process (Da et al, 2008) until sale or further processing. Most of these operations are powered by electric motors.…”

“…Other renewable sources of energy can also be used for starch drying, such as rice husk in regions where both cassava and rice are grown. At small and medium scale, solar drying is used instead of fossil fuels, which reduces energy consumption but has limitations in terms of production capacity and risk of contamination by dust during drying (Da, 2008).…”

“…In addition, biogas systems reduce the surface of land needed for water treatment, and provide between 70 and 100% of the starch factory energy needs (Plevin and Donnelly, 2004). At small and medium scale, wastewater management practices are still scarce, and wastewater, with COD levels in the range 4800-13,500 mg/L, is often discharged directly in the surrounding river or canal system, resulting in significant levels of pollution (Colin et al, 2007;Da, 2008;Tran Thi My Dieu, 2003). Different factors underlie this situation: small factory operators may not be able to afford the investment required to build water treatment facilities (Peters et al, 2000;Peters, 2005), while the lack of land availability, due to high population density (Hanoi region, Vietnam) or mountainous area (Cauca department, Colombia), also restricts investments.…”