African Products has four mills in South Africa - at Meyerton, Kliprivier, Germiston in Gauteng and Bellville in the Western Cape - as well as a sorbitol plant in Chloorkop, Gauteng. Kliprivier mill is the biggest of the four mills, a modern starch processing plant with a corn (maize) grinding capacity of 1,200 tons per day. Novozymes' enzymes help to keep this African Products plant running efficiently. It was opened in 1998 after an investment of ZAR 800 million. In 2002, a further investment was made in saccharification, storage and loading facilities in order to expand production.
The products
A single raw material source - corn - is utilised to manufacture a wide range of products for an equally diverse variety of industries such as food, beverages, pharmaceuticals, textiles, paper-making and adhesives.
Corn contains about 70% starch, 18% fibre, 5% protein and 6% germ. After steeping the corn in warm water to rehydrate it, it is ground down using a wet-milling process. There are then various steps to separate the starch from the fibre, oil and protein. The resulting starch can either be dried as it is or modified by enzymes to produce sweeteners.
Industrial enzymes are required to convert the starch into food-grade glucose products with various sugar spectra. Products are tailored to the requirements of the customers, which include bakeries, confectioners a nd breweries for glucose syrups and the paper and textile industries for starch.
"I am impressed by how Novozymes continuously develops new and improved enzymes. We benefit by having efficient enzymes and the technical service provided, which is very important to us. This helps our operating teams to understand the process conditions needed for the optimal use of enzymes," comments Charles Macu, the Operations Director of African Products.
The enzymatic conversion at Kliprivier Mill begins with Liquozyme® Supra at a high temperature of 105-110°C. Liquozyme Supra is a new liquefaction enzyme that was first introduced at the mill in early 2005 when the mill switched from Termamyl® Supra. It is added in a jet cooker, where a jet of steam and a jet of starch slurry meet under pressure and the starch literally 'pops' open (gelatinisation). This allows Liquozyme Supra, an alpha-amylase, to act on this porridge-like intermediate product to produce dextrins, i.e. the gelatinous slurry is liquefied by the alpha-amylase to form dextrins that can be further broken down (hydrolysed) to glucose and maltose.
Saccharification is the next step after liquefaction. When producing high dextrose syrups with more than 95% DE (dextrose equivalent), African Products at Kliprivier uses Dextrozyme® GA (a glucoamylase). The reaction time is 48 hours at a temperature of 58°C to re ach 95% dextrose content. Saccharification takes place in eight reactor tanks. The resulting syrup is purified by traditional membrane filtration and ion exchange. At the end, the corn has been transformed with the help of Novozymes' enzymes into glucose syrup that is sold on the South African market and for export.
Novozymes supplies the majority of the enzymes used at Kliprivier. They are supplied through Novozymes SA, Novozymes' subsidiary in South Africa, which has offices and warehouses in Johannesburg. Jannie Van Aswegen, technical executive at Novozymes SA, serves the Kliprivier mill, while his colleague in technical sales, Thandanani Mbandlwa, serves African Products' Germiston mill.