Water kefir grains
学名: Mixed community in dextran polysaccharide matrix — Lactobacillus hilgardii (dextran producer), L. hordei, L. nagelii, Bifidobacterium aerophilum, Saccharomyces florentinus, Hanseniaspora valbyensis, others
デキストラン基質の半透明ジェル状粒子、砂糖水(時にドライフルーツと共に)を微発泡の乳製品不使用プロバイオティック飲料に発酵
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この培養菌について
Water kefir grains (called tibicos in Mexican Spanish, tibi in some English-language sources, aqua kefir or sugar kefir in commercial branding) are the dairy-free cousin of milk kefir grains. The grains are smaller, translucent rather than opaque white, gel-like rather than firm, and bind together via a dextran polysaccharide matrix produced by Lactobacillus hilgardii — distinct from milk kefir's kefiran matrix produced by L. kefiranofaciens.
The community composition is meaningfully different from milk kefir: - *Lactic acid bacteria: Lactobacillus hilgardii (primary dextran producer), L. hordei, L. nagelii, L. casei, L. paracasei* - *Bifidobacteria: Bifidobacterium aerophilum, B. psychraerophilum* - *Yeasts: Saccharomyces florentinus, Hanseniaspora valbyensis, Kluyveromyces lactis, Pichia fermentans* - *Acetic acid bacteria*: occasional contributors
The ferment uses sugar water rather than milk as substrate. Typical home preparation: 4-5 tablespoons cane sugar dissolved in 1 liter water, plus 3-4 tablespoons of water kefir grains, with a few pieces of dried fruit (raisins, figs) and a slice of lemon for minerals and pH buffering. Ferment 24-48 hours at 20-25°C in a glass jar covered with breathable cloth. Strain out the grains and reserve for the next batch; the liquid is the finished water kefir.
The flavor profile is meaningfully different from milk kefir — sharper, more wine-like, less creamy. The slight effervescence comes from yeast-produced CO₂. The ethanol content is typically 0.3-1.5%, similar to kombucha. Secondary fermentation in sealed bottles with added fruit juice produces stronger carbonation and fruit-flavored variants.
The origin tradition is also distinct — water kefir grains are believed to have originated in Mexico (the tibicos name comes from the Aztec tibik, meaning 'thin liquid'). Spanish colonizers carried the culture to Europe in the 16th-17th centuries; subsequent global spread followed. Modern molecular analysis confirms genetic distinction between water kefir grains from different geographic sources, suggesting either independent origins or significant regional drift.
Unlike milk kefir grains, water kefir grains require mineral supplementation. Cane sugar provides energy but lacks the calcium, iron, and trace minerals the community needs for sustained activity. Dried fruit (raisins, figs, dates) and a small slice of lemon provide these. Some water kefir keepers add molasses or eggshell powder to maintain grain health over many cycles. Pure white sugar with no mineral source produces grains that weaken and eventually fail.
The grains multiply more rapidly than milk kefir grains under good conditions — doubling in 1-2 weeks is normal. Excess grains can be dried for storage, gifted, or consumed (they are edible if not particularly appealing). Refrigerated storage is possible but extends only a few weeks without feeding; dehydrated storage is the standard for long-term archival.
微生物分類
最適条件
この菌を使う発酵食品
この培養菌の扱い方
- Use cane sugar plus mineral source (dried fruit, lemon slice, pinch of molasses) — pure white sugar with no minerals weakens grains over time.
- Maintain 1:20 to 1:30 grain-to-water ratio — too few grains slow fermentation; too many over-ferment.
- Ferment 24-48 hours depending on temperature — taste daily after 24 hours to find target sweetness/sourness.
- Strain through plastic or stainless mesh — avoid reactive metals.
- For carbonation, bottle with added fruit juice and seal 1-3 days at room temperature — secondary ferment produces stronger effervescence.
よくある失敗
- Using only white sugar with no minerals — grains weaken and eventually fail. Dried fruit and lemon are not optional.
- Confusing water kefir grains with milk kefir grains — different communities, different substrates, not interchangeable.
- Trying to ferment water kefir grains in milk — the substrate mismatch causes the grain community to die over a few cycles.
- Refrigerating grains for weeks without feeding — kills the culture slowly.
- Sealing primary fermentation tightly — needs oxygen exchange; sealed batches stall.