By Zama Khwela, Postgraduate Diploma in Media Management student
The South African Sugar Association (SASA) recently invited Rhodes University and several media organisations to their annual media tour, which took place between 28-29 November in KwaZulu-Natal.
The two-day tour was entitled “From sugar farm to sugar bowl” and involved a walkthrough of SASA’s farming facilities, the South African Sugarcane Research Institute (SASRI) and a full tour of the Sezela Mill.
28 November
Cedric Mboyisa, SASA Communications Manager, welcomed the group. Trix Trikam, CEO of SASA, spoke about the sugar industry and the state of the national markets. Sugar nutrition was covered by Priya Seetal, SASA’s Nutrition Manager.
The SASRI tour with Michelle Binedell, SASRI Knowledge Manager, consisted of a viewing of the grounds and insight into the research being done at the facility. The research component was established in 1925 to fight diseases and pests that most sugarcane varieties succumb to.
As we started walking, we saw the Biotech Building, the Quarantine Glasshouse, the Geographical Information Systems building and the library, the latter of which contains archives since 1925, making it the biggest sugarcane library in the southern hemisphere.
The Quarantine Glasshouse stores any sugarcane that crosses over the South African borders, to make sure that it does not contain any pests and diseases before it is used for breeding processes.
The farm at SASRI is not used for commercial production, but rather research purposes. It houses a variety of cane in terms of height, health, type etc. The SASRI staff showed us how the sugarcane is planted in the ground and how it is vegetatively propagated. Sugarcane is a tropical plant that is used to living on the equator and therefore, it produces higher yields in those areas.
The dead leaves that come off the cane, called crops residue, are a very valuable source of energy. “That’s really where our industry is starting to head into - opportunities for the co-generation of electricity that comes from the sugarcane crop residue,” said Binedell.
One of the complications of the plant is that it does not produce via pollen, as South Africa is too cold and too far south of the equator. In order to combat this issue, SASRI have built breeding facilities that produce cane that is conducive in the South African climate. The Photo Period House manipulates the day length and the temperature so that the cane produces a flower.
In terms of breeding, it is survival-of-the-fittest for sugar cane. Binedell explained that two parents are chosen to procreate and produce the best offspring. However, it can be a hit-and-miss situation because cane is more genetically complicated, so they pair a whole lot of parents to produce a whole lot of little offspring. This is the beginning of the story – the beginning of 10 to 15 years of selecting the strongest child out of the batch.
We were shown one of the research labs that test the farmers’ soil and crop residue samples. This is done to test how conducive the sugarcanes is to growth. The test also shows what amount of fertiliser should be used on the crop.
After the SASRI tour and lunch, we were introduced to Chef Jenny Morris, who did a cooking demonstration. “I want to show you that you cannot live without sugar in your life, whether it’s sweet or whether it’s savoury,” said Morris.
She prepared a rib-eye steak salad, incorporating fruit into it. “I believe that jam is not just a sandwich. You can take those beautiful sweet fruits and turn them in something good and savoury,” she said. She took us through the whole preparation process with the help of several assistants. Morris presented us with different desert and meal options for Christmas that incorporate sugar – which are fun to make! The entire cooking demonstration was filled with laughter and fun, breathing life and lightness into the rest of the afternoon.
29 November
Illovo Sugar South Africa has a range of operations, including the Sezela Mill. The Mill crushes around 2 million tons of cane per annum, producing about 230 tons of industrial raw sugar. From the same amount of crushed cane, they produce 90 tons of molasses, which goes to their alcohol plant. The plant produces potable alcohol that gets sold to different companies, which turn it into the alcohol you find in stores.
Typically, 16% of the mass of cane is fibre, about 13% is sucrose, and the remainder consists of a little bit of ash and water.
After the presentation on how the mill operates, we were taken down to the mill where we saw as much of the process as we could. Essentially, the process of sugar production begins when the cane arrives in by truck and goes through a series of leveller knives. Then it goes through a series of cane knives, which cut the cane into smaller pieces. From there, it goes through shredders, which smash the cane and expose the sucrose cells, which are to be extracted through the diffusion process.
During the diffusion process, water is introduced that passes through the diffuser absorbing sucrose. The process requires that the fibre and water go in opposite directions and from this, about 97% of the sucrose is extracted. At Sezela, they have dewatering mills that simply give the fibre a final squeeze to ensure that they have extracted as much as possible.
At this stage, the product goes to their downstream plant and comes back as residue. The juice from this process is called ‘mixed juice’, which goes through a set of heaters. The juice is heated up, lime is added to control the pH, and then it goes to a clarifier, which essentially separates the mud from the juice. The ‘mud’ is a form of fertiliser that goes back into the fields.
The evaporation stage takes place in Sezela’s five evaporators. During this process, the juice is heated in order for the water to evaporate, making the juice concentration increase from about 12% to 67% sucrose. This ‘syrup’ then goes through vacuum pans that boil, which turns the syrup into crystals. The crystals go through a crystalliser (for further growth), the centrifugal station and finally, sugar dryers. This is when you are left with the final product – sugar.
The entire experience provided by SASA was very informative. The sugar industry is an important one and being afforded the opportunity to understand the process, and all the research that goes into it, is an invaluable one.