Kombucha Flavors (F2)

Three reliable second-ferment flavors, each built on finished F1 kombucha from the house base: a punchy ginger, a deep berry, and a dry-hopped “kombucha pale” with citrus-pine aromatics. F2 is where flavor and natural carbonation come from — the residual yeast eats the added sugar in a sealed bottle and traps the CO₂.

Ingredients

Doses are per 500 mL bottle of finished F1 kombucha (pH 2.5-3.5), leaving 2-3 cm headspace. 1 Jar (1 L) ≈ two bottles; 1 Crock (4 L) ≈ eight bottles. Hops are aromatic, not a sugar source — they need a little priming sugar alongside.

Flavor	per 500 mL bottle	priming sugar
Ginger	12-18 g fresh ginger, grated (or 15 mL juice)	included in ginger; +3 g if low fizz
Berry	40-60 g mashed berries or 50 mL 100% juice	none (fruit sugar primes it)
Hopped	0.3-0.5 g dry hop pellets (e.g. Citra/Cascade)	4-5 g (1 tsp) sugar

Yield

About two 500 mL bottles per liter of F1, or eight per 4 L crock.

Calculated Values

• Starting pH (each bottle): 2.5-3.5 (your finished F1) — well below the 4.6 safety line. Confirm with a meter; see /docs/calc-ph-safety.
• Priming sugar target: 8-12% fruit/juice or 4-5 g sugar per 500 mL — enough to carbonate, not enough to burst.
• F2 temperature + days: 21-27 °C / 70-80 °F, 1-4 days sealed (ginger and hops can be slower; berry is fast).
• Finished pH: stays 2.5-3.5 — F2 adds aroma and fizz, not meaningful acid.

Readiness Window

1-4 days sealed at 21-27 °C. Warm rooms and sugary fruit carbonate in a day; cooler rooms and low-sugar additions take longer.

Done-when: a sealed bottle feels firm and a chilled test pour releases lively fine bubbles. Arrest by refrigerating at 2-4 °C, which slows the yeast and holds the carbonation.

Start from finished F1

Confirm your base kombucha is at pH 2.5-3.5 and pleasantly tart. Reserve next batch’s 15% starter before you flavor anything.

Prep the flavoring

For ginger, grate fresh ginger fine (more surface = more punch). For berry, mash fruit or measure 100% juice. For hopped, weigh the dry hop pellets and the priming sugar — hops carry no fermentable sugar, so the sugar is what carbonates.

Charge and seal the bottles

Add the dose to each pressure-rated swing-top bottle, top with kombucha to a 2-3 cm headspace, and seal. For hops, a small muslin bag keeps pellet sludge out of the pour.

F2 at room temperature

Hold 21-27 °C for 1-4 days. The closed bottle traps the CO₂ from the fresh sugar fermentation.

Burp daily, then chill

Briefly crack each cap over a sink once a day to check and release pressure. Once firm and fizzy, refrigerate at 2-4 °C. For hopped batches, chill stops the hop bitterness from creeping; drink within two weeks for the brightest aroma.

Caution

F2 builds real pressure and over-sugared or warm bottles can over-pressurize and burst. Use pressure-rated bottles only, keep added sugar in the stated range, leave headspace, and burp daily. If a bottle feels rock-hard, open it slowly over a sink with a towel over the cap, and refrigerate to arrest once carbonated. Glass shards from a burst bottle are a real hazard — when in doubt, refrigerate early.

Note

Flavoring does not change the safety picture: F1 already brought the brew to pH 2.5-3.5, and F2 keeps it there. The only F2 risk is mechanical (pressure), not microbial. Sealed sugar ferments raise alcohol slightly above F1; long, warm, sugary bottles produce the most.

Tip

Less is more on hops — 0.3 g per 500 mL reads as “bright citrus,” while 1 g tips into harsh, grassy bitterness in a low-pH drink. Dry-hop cold-side only; boiling hops in kombucha just makes it astringent.

Variations / mix-ins

• Ginger-turmeric: add 2-3 g fresh turmeric to the ginger bottle for color and earthiness (it will stain).
• Berry-basil or berry-lime: drop 1-2 basil leaves or 5 mL lime juice into the berry bottle.
• Hopped + grapefruit: a 10 mL splash of fresh grapefruit juice plays into Citra’s citrus notes and adds priming sugar.

🫙 House kombucha base

• Second ferment & carbonation

See also

• House kombucha base — the F1 these flavors build on
• Kombucha method and Second ferment — the F2 carbonation mechanics
• pH safety calculator and Acidity and pH
• Safety first — burping and bottle-pressure handling