LEGACY RESEARCH INVENTORY — NOT CURRENT FERMUNITS DOCUMENTATION

This file is preserved as historical planning and research context. It may
contain superseded formulas, unsupported claims, approximate values, proposed
names that were never implemented, or items still awaiting authoritative source
verification. See ../README.md and the maintained reference documents in the
parent directory for current FermUnits behavior.

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       MASTER FERMENTATION CALCULATOR SPECIFICATION - PART 7: ACID TIER
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A technical backend manual covering cellular population densities, lactic acid
mass titrations, volatile acidity safety limits, and food-safe concentration
metrics mapped directly to standard SI metric base and derived units.
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1. MICROBIAL POPULATION DENSITIES & BIOMASS VIABILITY
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*   Colony Forming Units per Milliliter (CFU/mL)
    - Description: The standard biological unit used to quantify the population density
      of live, active probiotic bacterial cells (Lactobacillus, Acetobacter) and
      fermenting yeasts per unit volume of liquid culture.
    - Core Users: Quality assurance food labs, kombucha brewers, kefir producers,
      and yogurt regulatory compliance teams.
    - Metric / SI Baseline Value: Volumetric particle concentration index.
      Expressed as: 1 CFU/mL = 1,000,000 active cell clusters per cubic meter (10⁶ particles/m³).

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2. ORGANIC ACID TITRATION BALANCES
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*   Titratable Acidity as Lactic Acid (% TA Lactic)
    - Description: Measures the mass concentration of lactic acid in fermented dairy,
      reported as a weight-to-volume percentage fraction. While wine scales prioritize
      tartaric acid and cider uses malic acid, dairy culture backends rely completely
      on a lactic acid baseline molecule.
    - Core Users: Yogurt manufacturers, cheesemakers, and commercial kefir processors.
    - Metric / SI Baseline Value: Mass per volume concentration fraction.
      Expressed as: 1% TA Lactic = 10 grams of pure lactic acid per liter of liquid (10 g/L = 10 kg/m³).

*   Volatile Acidity (VA)
    - Description: Measures the concentration of steam-distillable volatile organic
      acids—primarily Acetic Acid—present in active vinegar and kombucha cultures.
      Tracking VA is legally required to check SCOBY health and ensure a kombucha
      fermentation does not generate unauthorized trace levels of ethanol.
    - Core Users: Kombucha micro-brewers, industrial vinegar picklers, and food scientists.
    - Metric / SI Baseline Value: Mass concentration per volume unit.
      Expressed as: 1 g/L Acetic = 1 kg/m³ (SI Base: kg, m).

*   HIGH-PRECISION CONVERSION FORMULAS FOR ACID INTERSECTION:
    - TA as Lactic (g/L) to Wine Standard Tartaric Equivalent:
        Tartaric Acid (g/L) = Lactic Acid (g/L) * 0.833
    - TA as Tartaric to Dairy Standard Lactic Equivalent:
        Lactic Acid (g/L) = Tartaric Acid (g/L) * 1.200
    - Volatile Acidity to Total Acidity Contribution:
        Acetic Acid (g/L) = Titration Volatility Constant * Volume of NaOH (mL)

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3. SOLID INTEGRITY & DENSITY STABILITY
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*   Total Solids-Not-Fat (SNF %)
    - Description: Measures the mass percentage of dissolved and suspended dairy
      nutrients (proteins, lactose, minerals) remaining in milk after subtracting
      pure butterfat mass. This baseline determines the physical thickness, water-binding
      capacity, and structural gel stability of the target yogurt post-fermentation.
    - Core Users: Dairy engineering plants and cultured food laboratory analysts.
    - Metric / SI Baseline Value: Mass fraction percentage unit. Calculated as:
      (Dry Mass minus Fat Mass in kg / Total Sample Fluid Mass in kg) * 100 (SI Base: kg).

*   Brix-to-Acid Ratio (BAR)
    - Description: A calculated dimensionless sensory and chemical balancing indicator
      found by dividing unfermented substrate sugar density (Brix) by Total Acidity (TA).
    - High-Precision Balanced Equation:
        BAR = °Brix / Total Acidity (g/L)
    - Metric / SI Baseline Value: Dimensionless architectural indexing ratio.
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