Description: For my ENGR 103 Final project I decided to make hooch. Not quite hooch because bacteria in the SCOBY convert the alcohol to acetic acid keeping the alcohol content negligible. As fermentation continues the buildup of acetic acid lowers the pH of my not-hooch. I created a pH datalogger to track the fermentation of my not-hooch. The datalogger uses an ESP32 to log data from an analog pH probe and save the data to a microSD card. This is meant to be used to track the fermentation of Kombucha, but in this series of tests I used a sugar syrup with a known concentration as a benchmark with the goal of finding the relationship between sugar concentration and duration of fermentation needed to reach pH 2.5. The sugar syrup and SCOBY puck were placed in a jar on a hot pad and left to ferment and the pH was tracked for roughly 45 hours. Image 1: Close up of ESP32, breadboard, SPI breakout board, pH board, and wiring. Image 2: Close up of probe in fermenting sugar syrup. Image 3: Wiring Diagram All VCC --> ESP32 3v3 All GND --> ESP32 GND SPI CS --> ESP32 GPIO 5 SPI MOSI --> ESP32 GPIO 23 SPI SCK --> ESP32 GPIO 18 SPI MISO --> ESP32 GPIO 19 pH PO --> ESP32 GPIO 35 Image 4: Data The data collected deviated significantly from what was expected. given the high initial concentration of sugar I assumed that the pH would decay exponentially, and the fermentation reaction would slow with time with the bulk of the reaction happening shortly after starting collecting data. Over the first ~250min the pH probe showed rapidly decreasing pH, this is likely due to residual kombucha on the SCOBY mixing throughout the jar. After this the pH plateaus at 3.95 until ~800 min at which point it starts to decline. There is another plateau and subsequent decline which was unexpected. As this data is only over 45 hours, this may be of no significance. However the spacing of the plateaus and the time I started the test may indicate that rate of fermentation correlates with ambient light and/or temperature, as the plateaus both occurred at night. A longer Dataset spanning at least a week is needed to determine if this is the case. The jury is still out on if for a given initial concentration of sugar, the rate of decrease in pH is linear. Hopefully this can be cleared up by more data for different concentrations of sugar. Image 5: Full setup with pH data being seen live on laptop over serial port.