## 1 Introduction  
Indigenous drinks, also known as traditional beverages, are created by the inhabitants of a particular region, utilizing old techniques and locally farmed and sourced ingredients [1]. Traditional beverages from South Africa, for which maize or sorghum are valuable raw materials, are known as Umapmbothi [2]. Starch is a significant component in Umapmbothi production, as it serves as a carbohydrate source and as a thickening and suspending agent. These particles are suspended through starch gelatinization, making the beverage creamy. However, the complete conversion of starch is avoided [3; 4; 5]. Also, the Umapmbothi fermentation process is traditionally performed under uncontrolled conditions, adding to the challenge of producing a beverage with an extended shelf life [4; 5]. The production of Umapmbothi typically involves lactic acid and alcoholic fermentation. Due to their higher growth rate, lactic acid bacteria (LAB) fermentation dominates the early stages. At the same time, yeast gradually builds up in the latter part of the fermentation process [6; 7; 8; 9]. While it remains a traditional process, the brewing of Umapmbothi has benefited significantly from enhanced scientific knowledge and technology over the last century. The modern malting and brewing industry has pioneered various technical, biochemical, microbiological, and genetic inventions [10]. Transgenic malts and appropriate starter cultures in malting offer intriguing new possibilities for ensuring balanced enzyme activity and avoiding harmful fusarium contamination [11]. Several genetically modified brewer's yeasts have been developed, such as those encoding -acetolactate decarboxylaseand super-flocculating yeasts [11]. These and other advancements generally fail to adequately address the effect of malt milling on particle sizes and their impact on the quality of Umqombothi.  
In contrast to other traditional African beers, sorghum and maize malt are not milled or graded during the Umqombothi production process [10; 12]. Research must be conducted on the effects of varying particle sizes in the production of Umqombothi. Milling reduces particle sizes to the micron level, which enhances the carbohydrate solubility yield by releasing several enzymes; milling causes the physical breakdown of ingredients, which liberates soluble carbohydrates, without the need for external enzymatic treatment. Starch hydrolysis is greatly influenced by its physical state. The degradation of starch increases water absorption and enzymatic sensitivity, influencing the physicochemical qualities of starch as well [10; 12].  
Enzymes attach easier to amorphous starch regions, than crystalline starch regions. Enzymatic amylolysis of tiny and large starch granules occurs in different ways. Distinct sizes of starch granules have variable structures in terms of amylose and amylopectin ratios, resulting in different physicochemical qualities [10]. From the surface to the centre of the starch granule, amylopectin and amylose have a distinct structure that ranges from small and medium to large granules [10; 13]. The most commonly used enzymes in brewing for the hydrolysis of word are \(\alpha\)-amylase, \(\beta\)-amylase, and endo-\(\beta\)-1,3:1,4 glucanases [10; 14]. Because sorghum beverages have played a significant role in traditional civilization, it is critical to understand the impact of particle size on malts. However, the number of studies conducted in this area is limited, especially information on the effect of particle sizes on the production of Umqombothi. This study aimed to evaluate the effect of particle size on the physiochemical, microbiological, stability, and sensory characteristics of Umqombothi. It is hypothesized that reducing the particle size of the malt will improve the stability and sensory characteristics of Umqombothi.