Quality Control — Fat Processing

Testing hierarchy from free sensory checks to quantitative titration. The reference sample is the most important tool.

Testing Hierarchy

Test	Frequency	Time	Cost	Measures
Sensory (color, smell)	Every session	2 min	Free	Overall condition proxy
Paper towel test	Every session	5 min	Free	Polar compounds, particulates
Water drop test	Weekly	2 min	Free	FFA proxy
Baking soda effervescence	Weekly/incoming	5 min	Free	FFA (qualitative)
FFA titration	Monthly/post-processing	15 min	<$1	FFA% (quantitative)
Starch-iodide peroxide	Quarterly	20 min	$2	Peroxide value (semi-quant)
Color comparison	Monthly	5 min	Free	Color body accumulation trend

The Reference Sample System

Keep a sealed small jar of freshly processed stearin as a permanent standard:

• Best available quality, freshly processed
• Store dark, cool, sealed
• Replace every 6 months
• Use for: color comparison, odor comparison, water drop comparison
• Photograph each test for trend tracking

Reference standard specs:

• FFA: <0.3%
• Color: ivory-white
• Odor (warm): neutral, mildly fatty
• Water drop: discrete bead maintained

FFA Titration — Full Procedure

Materials: IPA (99%), phenolphthalein indicator, 0.1M NaOH (4g food-grade NaOH per liter distilled water), scale (±0.1g), syringe or dropper

1. Weigh 5.0g melted fat exactly
2. Add 10ml IPA, warm to 50°C until clear
3. Add 3 drops phenolphthalein (solution colorless)
4. Add 0.1M NaOH drop by drop, swirling between drops
5. Endpoint: first persistent pink lasting 30 seconds

Calculation: FFA% = (ml NaOH × 0.1 × 282 × 100) ÷ (sample weight × 1000)

Example: 0.5ml NaOH, 5.0g sample → FFA = (0.5 × 0.1 × 282 × 100) ÷ (5000) = 0.28%

Acceptance criteria:

• <0.5%: Release — meets specification
• 0.5–1.0%: Acceptable — monitor

• 1.0%: Reprocess — additional ethanol wash + repeat Phase A

Sensory Tests

Paper towel test: Dip white paper towel in fat at 60°C. Clean fat = even pale yellow absorption, no dark patches. Degraded fat = dark patches, uneven absorption, visible particulate residue. Run after each bentonite treatment — endpoint when successive treatments produce no improvement.

Water drop test (FFA proxy): Place fat drop on clean dry glass. Add water drop. Pass = discrete water bead maintains surface tension. Fail = water spreads and partially emulsifies (FFAs acting as emulsifiers at fat-water interface).

Baking soda effervescence: Add 5ml baking soda solution to 50ml fat sample. Vigorous sustained bubbling = high FFA. Mild brief = moderate. None = low FFA. Use as incoming quality assessment and post-processing check.

Bentonite Saturation Indicator

Fresh bentonite: pale tan to grey-white. Spent bentonite: darkens toward amber-brown proportional to oxidized compound load.

• Spent bentonite exits already dark → fat had high contamination load, continue treatment
• Spent bentonite similar to fresh → fat was relatively clean, treatment is complete

Diminishing returns endpoint: Plot FFA or color measurement after each treatment. Continue until the improvement curve flattens — where another treatment produces no measurable improvement. This is both the quality endpoint and the economic optimization point.

Connections

• [[11-Step Protocol]] — the process being tested
• [[Aqueous Phase Chemistry]] — what's being removed
• [[Solvent Phase Chemistry]] — what's being removed
• [[In-Fryer Antioxidants]] — prevention upstream