STARCH & DERIVATIVES | astarscassava

ASTARS STARCH & DERIVATIVES

The Starch & Starch Derivatives SBU will produce native tapioca starch and starch based sugars from sustainable cassava feedstock. This SBU will seek to be a leading producer of starch and Starch Derivatives for the food additives markets both in Zimbabwe, regionally and internationally.

Cassava now provides about 30% of worldwide production of roots and tubers and is the staple crop of over 200 million people in Africa alone. World production of cassava has increased more than 4-fold in the last 20 years, with most of this increase being in Africa. Africa however remains a net-importer of starch and Starch Derivatives for edible and industrial applications despite the continent having the skills and resources to be a leading global producer and exporter of the products. Starch, in and of itself, is one of the most abundant substances in nature, a renewable and almost unlimited resource. Starch is produced from grain or root crops and is mainly used as food, but is also readily converted chemically, physically and biologically into many useful products. To date, starch is used to produce such diverse products as food, paper, textiles, adhesives, beverages, confectionery, pharmaceuticals and building materials.

Cassava starch has many remarkable characteristics, including high paste viscosity, high paste clarity and high freeze-thaw stability, which are advantageous to many industries. Cassava is an extremely versatile and vertically-integrated plant that can be processed into starch for both food and industrial uses as depicted in below:

For cassava, the process of starch extraction is relatively simple as there are only small amounts of secondary substances in the roots. When cassava roots are harvested or selected for starch extraction, age and root quality are critical factors. Cassava roots need to be processed almost immediately after harvest, as the roots are highly perishable and enzymatic processes accelerate deterioration within 1-2 days. It is therefore imperative that sufficient cassava is dried and stored for use as and when required. In general, fresh tubers are processed during the season and also during the off-season. A first-grade quality starch can be obtained from cassava using only water and this makes the processing of cassava starch particularly suitable for developing countries and rural industries.

Cassava starch is produced primarily by the wet processing of fresh cassava roots. Starch in the form of carbo-hydrates is the main constituent of cassava. About 25% starch can be obtained from mature, good quality, fresh tubers. Extraction of starch from fresh cassava roots can be divided into four main stages: preparation (crushing), liquefaction, filtering (starch washing, dewatering and drying) and finishing (milling and packaging). The process flow is represented diagrammatically below: