No stringy texture (natto)

Temperature too low or not enough time; extend incubation

Too strong ammonia smell

Normal for alkaline ferments; fermentation may be complete

Incubation environment contaminated; sterilize equipment

Slimy but not stringy

Wrong bacteria; use verified Bacillus subtilis starter

Ensure even heat distribution; stir beans before incubating

Alkaline Fermentation

Alkaline fermentation uses Bacillus bacteria to break down proteins in an alkaline environment, creating pungent, umami-rich foods.

Overview

Alkaline fermentation differs from acid fermentations - instead of lowering pH, it raises it. Bacillus bacteria, particularly Bacillus subtilis, break down proteins into amino acids and ammonia, creating strongly flavored foods with intense umami characteristics and distinctive aromas.

The Science

Bacillus bacteria produce proteolytic enzymes that break down proteins into amino acids and peptides, releasing ammonia as a byproduct. This ammonia raises pH to alkaline levels (pH 8-9), creating an environment where Bacillus thrives but most pathogens cannot survive. The protein breakdown produces high levels of free glutamates, responsible for intense umami flavor.

Common Foods

Natto (Japanese fermented soybeans)
Dawadawa (African locust beans)
Thua nao (Thai fermented soybeans)
Kinema (Himalayan fermented soybeans)
Cheonggukjang (Korean fast-fermented soybeans)

Tips

Temperature control is important - Bacillus thrives at 100-115°F. The fermentation produces strong ammonia odors; this is normal. Starters (existing natto or Bacillus spores) ensure successful fermentation.

Temperature Guide

Optimal incubation: 100-115°F (38-46°C) — Bacillus thrives in warm conditions
Natto fermentation: 100-105°F (38-40°C) — 24 hours produces classic natto
Extended fermentation: 95-100°F (35-38°C) — Slower development, stronger flavor
Storage: Refrigerated — Slows continued fermentation

Troubleshooting

No stringy texture (natto): Temperature too low or not enough time; extend incubation
Too strong ammonia smell: Normal for alkaline ferments; fermentation may be complete
Mold growth: Incubation environment contaminated; sterilize equipment
Slimy but not stringy: Wrong bacteria; use verified Bacillus subtilis starter
Uneven fermentation: Ensure even heat distribution; stir beans before incubating

Required Starters

Bacillus subtilis spores (natto starter powder)
Existing natto as starter
Traditional methods use rice straw (naturally contains Bacillus)
Commercial natto starter widely available online