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contain superseded formulas, unsupported claims, approximate values, proposed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 5: CIDER & PERRY
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A technical backend manual covering non-fermentable sugar-alcohol tracking,
phenolic concentrations, total sulfur dioxide management, apple classification
metrics, and industrial volume indicators mapped directly to standard SI units.
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1. NON-FERMENTABLE FRUIT METRICS & EXTRACT DENSITY
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*   Sorbitol Mass Tracking (g/L)
    - Description: Sorbitol is a natural, six-carbon sugar alcohol found inside
      apples and pears. Because standard cider and wine yeasts lack the enzymes
      to digest it, sorbitol passes through fermentation entirely intact. Cidermakers
      must track its concentration to explain why a cider's Final Gravity remains
      unusually high even when all primary sugars have depleted.
    - Core Users: Industrial Cidermakers and advanced Craft/Micro Perry producers.
    - Metric / SI Baseline Value: Mass concentration per volume unit.
      Expressed as: 1 g/L = 1 kg/m³ (SI Base: kg, m).

*   Apparent Attenuation vs. Fruit Attenuation (%)
    - Description: A calculated percentage tracking sugar consumption that factors
      in the unfermentable sorbitol offset to find the true yeast efficiency.
    - High-Precision Multi-Variable Equation:
        True Fruit Attenuation = [(OG_GU - FG_GU) / (OG_GU - Sorbitol_GU)] * 100
        *(Where GU is Gravity Points and Sorbitol_GU represents the gravity density
        imparted solely by residual sorbitol mass, roughly 0.0037 SG points per g/L).*

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2. PHENOLIC CHEMISTRY & FRUIT GRADUATION MATRIX
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*   Total Phenolics (Tannin Percentage)
    - Description: Measures the mass percentage of polyphenols and astringent tannins
      extracted from apple and pear skins during pressing. This metric legally and
      structurally separates culinary apple juice from bitter vintage cider fruit.
    - Core Users: Commercial orchard managers, pomologists, and craft blending teams.
    - Metric / SI Baseline Value: Mass percentage fraction unit.
      1% Tannins = 0.01 kg of pure polyphenolic compounds per kg of pressed must.

*   The Long Ashton Research Station Fruit Classification Index
    - Description: A standardized logical sorting grid utilized inside calculator
      backends to tag and classify raw juice profiles based on Titratable Acidity (TA)
      and Total Phenolics.
    - Logical Grid Metrics:
        - Sweet Fruit        : Acid < 4.5 g/L Malic | Tannin < 0.18%
        - Sharp Fruit        : Acid > 4.5 g/L Malic | Tannin < 0.18%
        - Bittersweet Fruit  : Acid < 4.5 g/L Malic | Tannin > 0.18%
        - Bittersharp Fruit  : Acid > 4.5 g/L Malic | Tannin > 0.18%

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3. MALIC ACID TITRATION & FRUIT ACIDS
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*   Titratable Acidity as Malic Acid (g/L Malic)
    - Description: Measures the concentration of organic fruit acids in cider must.
      While wine utilizes a Tartaric Acid standard, the baseline organic acid in apple
      and pear juice is Malic Acid.
    - Core Users: Universal across all industrial, craft, and hobby cidermaking tiers.
    - Metric / SI Baseline Value: Mass concentration per volume.
      Expressed as: 1 g/L Malic = 1 kg/m³ (SI Base: kg, m).

*   CONVERSION FORMULAS FOR ACID BLENDING:
    - TA as Malic to Wine Standard Tartaric Equivalent:
        Tartaric Acid (g/L) = Malic Acid (g/L) * 1.119
    - TA as Tartaric to Cider Standard Malic Equivalent:
        Malic Acid (g/L) = Tartaric Acid (g/L) * 0.893

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4. ANATOMY OF FRUIT PRESS YIELDS & CAPACITIES
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*   Liters per Metric Tonne (L/t)
    - Description: Efficiency rating tracking the performance of industrial pomace
      presses (belt presses, bladder presses). It measures the raw volume of fresh juice
      squeezed from one metric tonne of milled fruit.
    - Core Users: Industrial and large commercial cider processing plants.
    - Metric / SI Baseline Value: Volume per mass index fraction ($0.001\text{ m}^3\text{ liquid / 1000 kg fruit}$).
    - Industrial Baseline: A standard efficient press run aims for 700 to 750 L/t.

*   Gallons per US Short Ton (gal/ton)
    - Description: The US Customary equivalent tracking juice yield per ton of fruit.
    - Core Users: North American commercial cider houses and orchard networks.
    - Metric / SI Baseline Value: Volume per mass index fraction ($3.78541\text{ L / 907.184 kg}$).

*   CONVERSION FORMULAS FOR PRESS YIELDS:
    - Gallons per US Ton to Liters per Metric Tonne:
        L/t = (gal/ton) * 4.1725
    - Liters per Metric Tonne to Gallons per US Ton:
        gal/ton = (L/t) / 4.1725
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