Gwatamatic

William Gwata standing in front of his invention

Gwatamatic is a patented design for a machine which cooks sadza. The machine comes in two models that is the Gwatamatic 2000 and the Baby Gwata. This is a local invention which was engineered by William Gwata. Among many of the conveniences that the invention affords the user is the ability of the machine to undertake all the cooking stages of sadza on its own, thereby insuring very hygenic standards throughout the cooking process.^[1]

Operation of the Machine (Gwatamatic 2000)

The machine is tailor made for industrial purposes and has three basic units which include a dispenser/stirring (mugoti) which feeds mealie meal into the pot. Then there is also an electronic control unit which basically controls the cooking process. The third and final component is a pot in which the sadza is cooked.^[1] The actual coking of the sadza takes about 45 minutes in which the Gwatamatic heats the water, mixes the hot water with maize meal and allows the mixture to boil, until the final process of adding more maize meal to adjust the texture of the sadza to when the sadza is ready for serving. the cooking device also allows for the cooked sadza to simmer for a while and all the aforementioned processes are all controlled and regulated by the machine on its own.^[1]

Characteristics of the Gwatamatic

Hygiene

By eliminating human contact throughout the cooking process the machine avoids contamination of the sadza from foreign bodies such as sweat, hair among other contaminants. Even when the one monitoring the cooking process does not get into contact with the cooked sadza when changing the stirring utensil to the next pot.^[1]

Mobility

The dispensing unit of the machine is mounted to the floor on one end and mounted on wheels at the other end which allows the operator to free up space above the pot in the serving process. The mobility of the dispenser also allows for the cooking of several pots of sadza to be cooked in succession.^[1] This basically means that the machine can work continuously 24/7

Components of the Machine

The Maize Meal Dispenser

The dispenser is responsible for feeding maize meal at the start of the cooking process soon after the water has boiled. The unit also feeds maize meal to the pot after the initial stage which allows the sadza to thicken to the desired thickness. The dispenser is a hopper with a turning screw worm at its base. Once it is filled with maize meal, the turning screw depending on the stage in the cooking cycle will then rotate and move maize meal into the pot. The dispenser has a "bridge disruptor" which is a turning rod in the dispenser which ensures that the screw worm is filled efficiently. The innovation was developed after the realisation that there were instances when the moisture content of the maize meal was out of spec causing it to clump over the turning screw. To ensure the safety of the operator and to keep out foreign objects the dispenser has a sieve over the hopper.^[1]

The Electronic Control Unit

The unit has an interface which allows the operator to initiate the cooking process as well as monitor the cooking process. The interface also contains administrators screens for the which allow the operator to set the cooking parameters. Once set, the operator cannot change the parameters.^[1]

The Pot

This is where all the cooking processes take place. The Gwatamatic 2000 has a carrying capacity of 500lt while the Baby Gwatamatic has a capacity of 250lt. Steam or electric heating methods are available for the two models with an upper volume limit of 250litres for the electrically heated vessels.^[1] Gwata highlighted that steam had a greater efficiency level considering that it took about eight minutes to heat 5000lt of water compared to the three hours taken by an an electrical element to heat 250lt of water. The pot is fitted with a double cavity into which the steam is pumped under pressure. The steam condenses on contact with inner surface (as the water in the pot is colder), upon condensing, latent heat is transferred into the pot bringing the water to boil and cooking the sadza. This video will make one better appreciate how the machine works.

Another interesting feature of the Gwatamatic is the fact that it has a sensor which allows it to cook sadza to the same consistency every time regardless of the quality of maize meal used. The sensor works by calibrating the relationship between the viscosity of the sadza and the amount of power pulled by the motor. This is determined by the resistance the impeller/mugoti encounters as it turns in the sadza. The greater the resistance the greater the viscosity which in turn draws more power from the circuit. The control is in effect a feedback loop that monitors the power being drawn and this is how it delivers exactly the same consistency in the sadza. The Gwatamatic 2000 has a retail price of US$39 9000 while the baby Gwata goes for US$19 000.