The effect of selected Non- yeasts and cold-contact fermentation on the production of low-alcohol marula fruit beer.

The last decade has seen increased consumer demand for zero and low-alcohol beverages. Cold-contact fermentation (CCF) in combination with non- can be an effective method for producing low-alcohol fruit beverages with desirable qualities. Thus, the aim of this study was to develop a CCF process to produce low-alcohol marula fruit beer using selected non- yeasts. The effect of temperature (°C), and time (h) on alcohol (% v/v), pH, total titratable acidity (LAE/mL) and specific gravity (SG) was evaluated using response surface methodology. Sterile marula fruit juice was inoculated with , , or respectively. Higher final SG values were observed for temperatures between 8 °C and 15 °C. Above 15 °C, the SG decreased with an increase in temperature and time. Fermentation at temperatures below 10 °C produced zero to low-alcohol marula fruit beer (0.00-0.20 % v/v) with an attenuation rate above 80 %. This was confirmed by the significance of quadratic models for SG ( ≤ 0.01), and alcohol ( = 0.00) for the three selected yeasts. Overall, produced the lowest alcohol levels, followed by and , respectively. The study confirmed that cold-contact fermentation with non- yeasts can be an effective biological method to produce low-alcohol marula fruit beer in line with the emerging consumer demand for low-alcohol beverages.