Technological Methods of Detoxification

Class 4

Why Detoxify?

Plants defend themselves with bitter or toxic chemicals (cyanogenic glycosides, alkaloids, tannins, oxalates)

Need to process them and detoxify foods to make safe and digestible

Antiquity of Food Processing

Controlled fire started about 500,000 years ago

Other methods (soaking, fermentation, leaching, drying) date back 10-15,000 years

Pros of processing

softens and improves digestibility

increases nutrient bioavalibility

removes toxins and harmful compounds

Cons of pocessing

loss of vitamins/ minerals

some toxins are resistant

energy intensive: balance of effort vs. calories gained

Heat as a tool

heat drives chemical reactions

converts toxins to less harmful forms

denatures toxic proteins (lectins, proteinase inhibitors)

roasting was likely the first technique

Fire and Human Evolution

fire expanded diet range

reduced pathogen (toxin) load

likely influenced human anatomy (smaller jaws, shorter guts)

provided evolutionary advantage over other primates

Boiling

requires watertight containers (clay pots, baskets + hot stones)

combines heat and leaching

salted water increased solubility

accelerates chemical breakdown

Leaching

water removes soluble toxins and bitterness

solubility varies by compound

repeated soaking or running water increases its effectivness

comminution (grating, pounding) enhances leaches (more surface area)

Comminution

Grinding, grating, pounding, freezing

break cell walls, releases toxic compounds

prepares foods for leaching, fermentation, or cooking

Ex: cassava (glycncyonide) must be grated before cooking

Fermentation

Microbes alter food chemistry

Detoxifies, preserves, enhances flavor

Requires controlled conditions (anaerobic, warm)

Ex: Sauerkraut, yogurt, bread

increases shelf life (increases acidity)

Adsorption

Clay and charcoal bind toxins

Explains geophagy (earth eating)

Used during food preparation or ingestion

Ex: clay mixed with bitter potatoes or acorns

Drying

Removes volatile toxins

Often paired with freezing or fermentation

Ex: andean freeze-drying (chuno)

pH Modification

Acids: vinegar, tamarind (hydrolyze compounds)

Tamarind pulp reduces calcium oxalate irritation

Alkaline: ash, lime water (hydrolyze glycosides, release niacin)

Nixtamalization of maize imported nutrition and safety

Physical Processing

Enzymatic release of toxins (glycosides → cyanide)

grating cassava key for safe consumption

Must be done before cooking

combines leaching and heat

Detoxification methods across cultures

Across:

• boiling or leaching (North America, Persia, Japan)

• Clay added (California, Sardinia)

• Ash Solution (eastern North America)

Cassava: grated, soaked, fermented, boiled

Clay and Acorns

California Pomo: mixed red clay with acorn meal → “black bread”

Sardinia: boiled acorns with ferruginous clay → baked into cakes

other groups: acorns buried in mud before use

clay binds tannins → sweeter, safer food

Potato Detoxification

Bitter potaotes transformed into tuna (chin blanco)

• steps: freeze at night, trample, soak in streams for weeks, dry in sun

reduces glycoalkaloids to about 3% of original

provides long term storable staple

Other ways of potato detoxification

chuno fresco: frozen → thawed → squeezed before cooking

peeling removes toxins in cultivated potatoes (not useful enough for wild species)

clay slurry dipping neutralizes bitterness and prevents GI distress

Practicies found in Andes and American Southwest

Clay and Other Plants

Western Australia: Haemodorum roots detoxified with clay

Ainu (Japan): Corydalis bulbs boiled with clay

American Southwest: Mesquite beans with clay

Datura fruits and Lycium berries with clay

Apocynum latex chewed with clay

Adsorption of Tomatine by Clay

John’s experiments with North and South American clays

Montmorillonite clays superior to kaolinite

Binding capacity varies by mineral structure

Clay slurry prevents bitterness and GI irritation in potatoes

Evolutionary Significance of Geophagy

Observed in primates and humans

likely ancient behavior

adaptive for dealing with toxins

linked to early domestication of potatoes

persists as cultural practice (pregnancy cravings, famine)

Trade offs of Detoxification

Nutrient loss: vitamins destroyed, minerals leached

Energy cost vs. caloric return

methods vary in effectiveness

Lectins are stable and unaffected by heat

false

What process do Andean farmers use to detoxify bitter potatoes into chuno

freezing, trampling, soaking, drying

Clays from North and South America were found to vary in adsorption capacity

true

Which statment best describes the balance of detoxification

It removes toxins but often at an energy or nutrient cost

Detoxification technologies allow humans to expand their ecological niche

True

____ pulp, rich in tactic acid is used to detoxify calcium oxalte

Tamarind

Which detoxification method relies on waters ability to dissolve soluble toxins

Leaching

Which plant compound releases hydrogen cyanide when hydrolyzed

cyanogenic glycosides

Communition increaess surface area and aids detoxification

true

Roasting was the first cooking method used by human

True