Background
The goal of this experiment is to run four parallel Amazake tests using different koji substrates and equipment setups to evaluate sweetness, sourness, and overall enzymatic activity.
The standard trials were conducted in the Alto-Shaam, with an additional duplicate rice trial run in a dehydrator to compare temperature consistency and heating rates.
Process
Four distinct batches were prepared using a 1:1:2 ratio (1 part koji, 1 part water, 2 parts secondary substrate):
- Wheat Koji: Prepared with Wheat koji.
- Oat Koji: Prepared with Oat koji.
- Sorghum Koji: Prepared with Sorghum koji.
- Rice Koji: Prepared with Rice koji and a secondary substrate.
Equipment
- Alto-Shaam
- Dehydrator (used for the duplicate rice koji batch)
Notes and Observations
Tasting Notes by Batch
- Sorghum Koji (Alto-Shaam): Came out extremely sour.
- Wheat Koji (Alto-Shaam): Not very sweet; exhibited slightly sour and bitter notes.
- Oat Koji (Alto-Shaam): Extremely sour.
- Rice Koji (Alto-Shaam): Sweeter than the other grain trials, but still carried a distinct sourness.
- Rice Koji (Dehydrator): This trial yielded the sweetest result. While still not quite as sweet as desired, it was noticeably superior to the Alto-Shaam batch.
Equipment and Temperature Analysis
The dehydrator performed significantly better than the Alto-Shaam for Amazake production. There are two primary hypotheses for why the dehydrator prevents the souring associated with lactic acid bacteria (LAB) activity:
- Heating Rate: The Alto-Shaam may take too long to bring the substrate up to temperature, allowing a window of lactic activity to occur before the heat kills off or inhibits the bacteria.
- Temperature Consistency: The dehydrator may hold a consistent 140°F (60°C) more reliably than the Alto-Shaam.
If using the Alto-Shaam in future trials, it may need to be set higher (perhaps 150°F–160°F / 65°C–71°C) to compensate, or the substrate must be pre-heated.
Ratio and Enzyme Observations
- When using fresh koji, a higher proportion of koji to secondary substrate might be necessary to ensure optimal enzymatic activity.
- Interestingly, increasing the substrate relative to the koji in the dehydrator trial still yielded roughly the same level of sweetness, suggesting the substrate ratio can be pushed higher under optimal temperature conditions.
Future Adjustments
- Reduce Incubation Time: Shorten the incubation window. Current trials ran for 14–16 hours; the next trials should be tested at 8 hours.
- Pre-heat Substrates: Pre-heat the secondary substrate and water before mixing with the koji to rapidly pass through the danger zone for lactobacillic activity.
- Alto-Shaam Calibration: Run a test in the Alto-Shaam at 150°F–160°F (65°C–71°C) to see if it prevents souring.
- Koji Ratios: Experiment with higher koji-to-substrate ratios when working with fresh koji to maximize amylase activity.