Bifidobacterium lactis Fermented Milk 


A bio-yoghurt style ferment using a yoghurt starter to support B. lactis BLa80 growth and acidification.

INGREDIENTS
• 1L whole milk (UHT)
• 30 grams skim milk powder
• 10 grams inulin or GOS (prebiotic, optional)
• 500 mg B. lactis BLa80 freeze-dried powder

STEPS
1. Fortify the milk: Whisk 30 grams skim milk powder and 10 grams inulin or GOS (prebiotic, optional) into cold 1000 milliliters whole milk (UHT or fresh) until fully dissolved. This lifts total solids to roughly 15% and gives the bifidobacteria more substrate and a firmer gel.
2. Heat treat: Heat the milk to 85-90°C and hold for 20-30 minutes. This denatures whey proteins for texture and drives off dissolved oxygen, which bifidobacteria dislike.
3. Cool and add cysteine: Cool to 38-40°C and dissolve in 0.5 grams L-cysteine HCl (optional, lowers redox potential). Skip this if you're relying on low headspace and oxygen-barrier packaging alone.
4. Inoculate: Rehydrate 0.1 grams freeze-dried yoghurt starter (S. thermophilus + L. bulgaricus), dosed per supplier sheet and 0.1 grams B. lactis BLa80 freeze-dried powder (assumes ~1×10¹¹ CFU/g; adjust to CoA) in a few tablespoons of the cooled milk, then stir gently through the batch. Avoid whipping air in. Target about 1×10⁷ CFU/mL of BLa80 at inoculation.
5. Ferment: Fill sanitised jars to the brim and seal to minimise headspace. Incubate at 38-40°C until pH reaches 4.6-4.7 (a set gel, typically 6-10 hours). Don't push past this, as bifidobacteria lose viability quickly in low pH.
6. Chill fast: Move jars to the fridge and get below 4°C within 1-2 hours to arrest acidification. Hold overnight before serving so the texture and flavour settle.

NOTES
Quality points: (1) Bifidobacteria are acetic-heavy and weak acidifiers alone, so the yoghurt starter does most of the pH drop; keep its dose modest to limit post-acidification during storage. (2) Enumerate BLa80 on MRS + 0.05% cysteine, anaerobic, 37°C for 72 h (add mupirocin for selectivity against the starter). Aim for ≥10⁸ CFU/g at packing and ≥10⁷ CFU/g at end of shelf life (about 14-21 days chilled). (3) Confirm dosing, storage and strain documentation with your BLa80 supplier's technical sheet, and note that any health claims on pack need to fit FSANZ Standard 1.2.7.