GIFSQ Tools · Module 07 — Dairy, Milk, Cheese & Fermented Products · Tool 128 of 500
Work out how much starter culture to add to a yogurt batch, as a volume at your inoculation rate and as direct-vat units.
Try sample values — fills the form with the worked example below.
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Starter to add (L)
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Direct-vat units (DCU)
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Milk (L)
Equation: Starter to add (L) = milk (L) × inoculation rate (%) ÷ 100. Direct-vat units (DCU) = milk (L) ÷ 100 × DCU per 100 L.
Method: Yogurt inoculation by volume rate for bulk starter, and by direct-vat units for frozen or freeze-dried culture, per the culture supplier’s dosing (yogurt cultures: Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, Codex Stan 243-2003).
Assumptions: the starter is evenly mixed through the milk; the rate is by volume; one DCU doses 100 L at the supplier’s stated rate.
Limitations: the volume does not guarantee activity — a weak or old starter needs a longer fermentation even at the right dose; always check the set time and final pH.
Rounding: volumes to 2 decimal places; DCU to 2 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Yogurt inoculation by volume rate for bulk starter, and by direct-vat units for frozen or freeze-dried culture, per the culture supplier’s dosing (yogurt cultures: Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, Codex Stan 243-2003).
Assumptions: the starter is evenly mixed through the milk; the rate is by volume; one DCU doses 100 L at the supplier’s stated rate.
Limitations: the volume does not guarantee activity — a weak or old starter needs a longer fermentation even at the right dose; always check the set time and final pH.
Rounding: volumes to 2 decimal places; DCU to 2 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: 500 L of milk at a 2% v/v inoculation rate, 1 DCU per 100 L. Starter = 500 × 2 ÷ 100 = 10.00 L; direct-vat units = 500 ÷ 100 × 1 = 5.00 DCU.
Enter values above to see results.
Bulk yogurt starter is usually added at 1–3% v/v; direct-vat culture is usually dosed at 1 DCU per 100 L. Tool 128 of 500 — GIFSQ
