Figure 8.3 Origin of some root and tuber crops.
More than 30 edible and non-edible species of roots and tubers are grown today. The important ones are cassava, potato, sweet potato, yam, cocoyam, ginger, taro and yam bean (Scott et al., 2000a, b).
Roots and tubers needs to be processed because they are highly perishable and tremendous losses occur after harvesting due to mechanical injury, bad handling practices, metabolic losses, respiration, microbial activities, actions of pests, rodents and diseases, sprouting, exposure to extremes of temperature, bulky and difficult to handle and vascular streaking amongst others. Therefore, roots and tubers are processed into various forms in order to increase the shelf life of the products, facilitate transportation and marketing, reduce toxicity and improve palatability.
8.4.1 Cassava Processing
The popular processed form of cassava tubers are meal, flour, chips and starch. The meal and the flour are the major categories used for food, especially in the tropics while cassava starch and chips are mainly industrial products that entered international trade. The meal forms include gari, High Quality Cassava Flour (HQCF), fufu, etc.
To produce high-quality cassava flour (HQCF) and fufu flour, it is important to adopt and implement the standards and food safety programme in the processing. Before implementing a food safety programme, HACCP, it is mandatory to first implement pre-requisite programmes like GMP, GHP and standard operating procedures. These products have to be produced according to the principles of Good Manufacturing
Practice (GMP) and Good Hygiene Practices (GHP), which provide operators with the basic rules of processing cassava in order to guarantee compliance with food safety and quality of the derived food products and therefore guarantee the consumers’ health, as well as to minimize quality losses.
(a) Good hygiene practices (GHP) for HQCF and/or fufu: may focus carefully on the personnel hygiene, designated eating areas, personnel hygiene facilities and hygiene establishment.
Cleaning aids required during the preparation of HQCF and fufu include the following: stiff brooms, soft brooms, soft brushes, hard stiff brushes, mop buckets, vacuum cleaners with accessories, net sponges, mechanical scrubbers, mops, sweeping brushes, long-handled brushes, water hoses and dusters. Cleaning chemicals may include detergents in the form of soaps, disinfectants, quaternary ammonium compound, etc. Responsible personnel should be put in charge of sanitation to monitor and check effectiveness of cleaning and maintenance, keep records of cleaning regimes and conduct regular auditing premises for sanitation and hygiene.
(b) Good manufacturing practices (GMP) for HQCF and/or fufu: GMPs are a combination of manufacturing and quality control procedures aimed at ensuring that products are consistently manufactured to their specifications. The good manufacturing practices are required in order to produce safe and high quality HQCF/fufu flour, are briefly illustrated:
(b.1) Fresh Cassava Production Point (Assurance of Quality of the Supplier)
• Cassava suppliers must ensure the quality and safety of the product.
In particular:
— Cassava farms must be appropriately located within environment, free from hazards.
— Plant pest and disease control measures must be undertaken with chemical, biological or physical agents often under the supervision of agricultural experts, with a thorough understanding of the hazards involving the possibility of toxic residues being retained by the crop.
— Farmers are to receive training in good agricultural practices, for example in the application of fertilizers, pesticides and how to store hazardous chemicals.
— Weeds must be controlled and destroyed from farm fields and soil must be well conditioned to allow maximum yield of crop.
— Plant diseases must also be controlled and managed effectively.
— Where possible, records on chemical and fertilizer application regimes as well as farm records should be kept for reference.
(b.2) Design and Facilities
Processing plants are not to be sited close to environments of high industrial pollution. The land must slope gently and have proper drainage system. Construction of facilities must keep out pests and permit adequate arrangement, maintenance, cleaning and functioning of equipment. The internal designs must be ideal for good hygiene practices and protection against cross-contamination during operation. Structures must be built with durable materials, which are easy to maintain, clean and disinfect. Design should minimize dust from flour during production. Walls and floors should be smooth, impervious and easy to sweep and wash. Ceilings and roofing should be well finished to minimize build-up of dirt, condensation and the shedding of particles. Windows should have insect-proof net screens that are easy to clean and allow proper ventilation to minimize the dust.
Food contact surfaces must be easy to clean, disinfect, maintain and should be non-toxic to the products. Iron reacts with cyanide so equipment made of this metal should be used with caution. All equipment used for peeling, washing, grating, de-watering, drying and milling are designed to achieve quality specification of products. There should be monitoring devices available to check product during production. Facilities should be available for handling, cleaning, waste disposal and ensuring personnel hygiene. There should also be adequate natural ventilation, good lighting and storage facilities. An example of a good layout for food processing is given in Figure 8.4.
Figure 8.4 An example of good layout for food processing.
(b.3) Walls, Floors, Windows and Roofs
Brooms and brushes must be used to scrub and clean walls and floor. High-pressure jets may be used for relatively inaccessible spots covered with tenacious soil, which cannot be dealt with by a brush. The type of cleaning, which involves high-pressure jets, should be done often for wet processing areas of cassava such as the peeling, grating and de-watering of pressing areas. Rubber strips of squeegees must be pressed in close contact with the floor by pressure on the handle and pushed along floor. Walls and floors must be scrubbed with detergent, rinsed and dried. However, for warehouse and storage room floors, vacuum cleaning of floors must be done to remove dust or spilled dried materials. Suitable vacuum cleaning attachments should be used to remove dirt from roof girders and to collect dust. Roof girders must be cleaned before floors. Order of cleaning must be planned so that dirt is washed down onto a surface still to be cleaned and not one that has already been cleaned. All cleaning must be worked from ceiling down to the floor. Scrubbing and mopping of floors, cleaning of windows and window screens must be done using clean water or vacuum cleaning.
(b.4) Cleaning and Maintenance
Equipment should be well-maintained to facilitate correct sanitation procedures and prevent contamination. Metal deposits from an attrition mill may result from poor adjustment of the mill plates, jewellery and contaminants (greases and lubricating oils) and should be avoided in the finished products of cassava. Physical and chemical cleaning as well as disinfection should be carried out regularly.
(b.5) Pest Control
Pest control is the prime responsibility and therefore staff must be responsible for monitoring the plant for rodent infestation and their elimination. The assignment should include baiting and recommendations on repairs that are necessary to keep out rodents. Access to processing and storage facilities by rodents must be completely avoided. Cracks and holes must be sealed and filled, once observed. Containers for storing food must be rodent proof. Traps must be placed along rodent pathways. Anticoagulant rodenticides may be used to kill rodents. Regular spraying of the environment with insecticides and the use of screen netting must be ensured to eliminate insects, cockroaches, houseflies, etc. Waste from the plant must be disposed of promptly to avoid the attraction of pests.