## 3 Results
### Effect of Particle Size on the Viscosity of Umqombothi during the Production Process
#### 3.4.2 The Effect of Particle Size on Umqombothi (Viscosity vs. Temperature)  
The apparent viscosity as a function of the fermentation temperature for the Umqombothi made with the control, coarse, and fine powder particle sizes (first and fourth stages) is presented in Figure 3. The control particle size during the fourth stage was initially 800.0 MPa\(\cdot\)s\({}^{-1}\) at approximately 0 \({}^{\circ}\)C and gradually decreased to 200.0 MPa\(\cdot\)s\({}^{-1}\) at 25 \({}^{\circ}\)C (Figure 3A). The same effect was observed during the first stage. It was initially 0.0 MPa\(\cdot\)s\({}^{-1}\) at approximately 0 \({}^{\circ}\)C and gradually decreased to -300.0 MPa\(\cdot\)s\({}^{-1}\) at 25 \({}^{\circ}\)C. Umqombothi made with the coarse powder particle size (fourth stage) was initially 200.0 MPa\(\cdot\)s\({}^{-1}\) at approximately 0 \({}^{\circ}\)C and gradually decreased to 100.0 MPa\(\cdot\)s\({}^{-1}\) at 25 \({}^{\circ}\)C (Figure 3B). The same effect was observed during the first stage. It was initially 10.0 MPa\(\cdot\)s\({}^{-1}\) at approximately 3 \({}^{\circ}\)C and gradually decreased to 5.0 MPa\(\cdot\)s\({}^{-1}\) at 25 \({}^{\circ}\)C, as indicated.  
Figure 2: Apparent viscosity of (**A**) control particle, (**B**) coarse powder particle, and (**C**) fine powder particle sizes of Umqombothi as a function of time at a constant shear rate (500 s\({}^{-1}\)). Before the first fermentation (BFF), after the second fermentation (ASF).  
The viscous properties of Umqombothi (first and fourth stage) showed a decreasing effect when the temperature was increased at a constant shear rate (500 s\({}^{-1}\)). The above-observed trend reveals Umqombothi's shear-thinning pseudoplastic behavior, namely the absence of shear and temperature results in a higher viscosity and its application results in decreased viscosity. Before fermentation, the viscosity of all the beer samples (control, coarse, and fine powder particle sizes) in regard to the viscosity vs. temperature was higher than 200 MPa\(\cdot\)s\({}^{-1}\). As much as the viscosity of all the beer samples decreased, they did not go below 100 MPa\(\cdot\)s\({}^{-1}\). The viscosity of cereals decreases due to the conversion of starch by LAB into simpler sugars during fermentation. The pH, the type of microorganisms, and whether those microorganisms include amylase enzymes that hydrolyze starch into dextrin and sugars, all impact the beverage's viscosity [20]. The viscosity and nutritional value of the solution improved in various ways due to the breakdown of starch by LAB [20]. These findings concur with those of [39], who noted a reduction in viscosity following the fermentation of a conventional fermented beverage (Boza) at 20 \({}^{\circ}\)C. According to [39], heating reduces viscosity by decreasing the molecular entanglement and stabilizing the molecular structure of sugar and protein.  
Finally, rheological information about Umqombothi may be helpful in the design and choice of machinery needed for industrial production. It is significant in this context to consider Umqombothi's pseudoplastic behavior concerning temperature, as indicated by the flow behavior index and consistency index values. The processing needs for the synthesis of Umqombothi may also depend on biochemical changes during fermentation, such as the pH and changes in water-soluble proteins.