Cassava is one of the most important tuber and starch crops in tropical countries. This tuber is mostly used as a source of food and starch products. The major cassava producing countries are Nigeria, Thailand, Indonesia, Brazil, Angola, Ghana, Congo, Vietnam, Cambodia and India. The total production of cassava all over the world is around 277.8 Million Tonne (MT). In India, it is cultivated about 0.22 million hectare with total production of 4.65 million tonne (MT) and a productivity of 20.39 tonne per hectare. Cassava tubers have a lot of moisture in them and they can spoil quickly. When damaged, the tubers even spoil more quickly. After harvesting, cassava tubers deteriorate rapidly. The maximum shelf life of cassava tubers after harvest is about 48 hrs at room temperature. Thus, it must be consumed or processed into value-added products namely cassava chips, cassava flour, and cassava starch.
Opportunities and Demand
Easy availability of cassava flour as a raw material is the reason for increased consumption and production of pre-gelatinsed cassava flour in consumers on a daily basis. The main factor boosting the growth of pre-gelatinised cassava flour market is increasing demand for gluten-free products and shifting the preference for baked products. Rising health awareness and a gluten-free diet are the driving factors for growth in pre-gelatinised cassava flour market. The pre-gelatinised flour market is broadly categorised into major segments based on the application type such as bakery industry, industrial food industry and animal feed sector. Due to the rising consummation of bakery, processed food and ready-to-cook meals, and increasing demand from production of confectionery food products, dairy desserts and drinks, frozen foods, and sauces, the bakery industry segment is growing rapidly in the market with substantial revenue generation in the last few years.
Commercial Production
Cassava flour contains starch, fibre, sugars, and small quantities of lipids and other components. It exhibits properties different from those of cassava starch, which cooks to a more cohesive paste. Pre-gelatinised cassava flour has highly digestible starch which is derived from cassava flour. It can be produced either prior to drying and milling process or after drying and milling process of cassava tubers. It is made using a variety of processes such as drum drying, spray drying and steaming. The process allows the starch granules in the cassava flour to have increased absorption and better dough hydration.
The type of process used to make pre-gelatinised cassava flours imparts different functionalities in the flour and moreover retains most of the functional properties and viscosity of the original cassava flour. The physico-chemical and functional properties that significantly varies with varieties and processing methods that affect the applications of the pre-gelatinised cassava flours.
Pre-gelatinised cassava flour is basically pre-cooked, dried and grounded for its use in food industries. Traditionally, roasting or steaming the dried cassava flour is the common way to produce pre-gelatinised cassava flour. It is produced commercially by preparing cassava mash. Whole or grated peeled cassava tubers are cooked using a combination of heat and pressure. The mash is heated above the gelatinisation temperature (65-75°C) of cassava starch and then dried. Alternatively, steaming process at low pressure can also be employed to complete the gelatinisation of the starch in cassava flour without an increase in moisture content.
Application
Pre-gelatinised cassava flour can be used in gluten-free baking, high volume bread, batters and nutraceutical and pharmaceutical applications. Since starch is the major component of the cassava flour, the changes of its physico-chemical properties during hydrothermal treatment will dominate the properties of pre-gelatinised cassava flour. It appears to have high potential for textural and structural improvement by reduction of starch retrogradation in bakery products. In gluten-free baking, pre-gelatinised cassava flour can increase baked product volume by increasing dough viscoelasticity. Studies indicate that it acts as a binder that improves the dough capacity to retain water, thus increasing viscosity and helping to retain gas cells within the gluten-free system. For best results in baking, it should be used in combination with other flours and starches. It also provides many functions such as viscosity control, texture control, thickening agent and bulking agent. Pre-gelatinised cassava flour rehydrates instantly in water providing a uniform high viscosity batter without the need for heat. The property of quick water absorption gives advantages like dough hydration, improving fresh keeping of baked food and stabilises dough and easy digestion. Food products prepared using pre-gelatinised cassava flour has a very good shelf life and this flour can also be used as a replacement for traditional emulsifiers and thickeners such as methylcellulose or guar gum. It can be widely used for baby foods, cakes, instant puddings, fruit pie, fillings and instant gravies
The specific functional properties of heat-processed pre-gelatinised cassava flours could simplify their incorporation into certain products formulations such as baked foods and gluten-free functional foods. This may lead to better utilisation of local starch sources and a potential cost reduction via substitution of imported ingredients.
(Krishnakumar and Giri are scientists and Sajeev is principal scientist, Division of Crop Utilization, ICAR-CTCRI, Trivandrum, Kerala. They can be reached at krishnakumar.t@icar.gov.in)