Extracts and By-products: Materials from Plants, Fungi, and Food Waste

Difficulty: mostly easy. Almost nothing here needs a furnace. Prerequisites: pottery or other vessels, water, cloth for straining, gentle heat, and in a few cases the still from basic chemicals.

Why it matters

Other guides in this repository mention starch, pectin, gelatin, tartrates, saponins, and fungal materials in passing, as ingredients in someone else's recipe. None of them explains how you actually get the substance. This page is the extraction-and-use view.

Two things make it worth its own page.

First, most of these come from what another process throws away. Tartrates crystallize on the inside of a wine cask. Pectin is in the apple pomace left after pressing cider. Gelatin comes from the hooves and trimmings that tanning discards. Whey is a cheesemaking by-product. In an economy where materials are scarce, the waste stream of one craft is the feedstock of another, and noticing that is worth as much as any single technique.

Second, they need almost no capital. A pot, water, cloth, and patience. When charcoal is your binding constraint, processes that need none of it are disproportionately attractive.

Part 1: Starch

Sources: potato and other tubers, wheat, rice, maize, arrowroot, sago, and cassava — noting that cassava must be processed to remove cyanogenic compounds before anything derived from it is used as food. Potato is usually the easiest because the granules are large and settle readily.

Extraction — the same settle-and-decant logic used everywhere in this repo:

1. Grate, crush, or mill the raw material as finely as you can, into water.
2. Work it vigorously to release the granules, then strain through cloth to remove fibre and pulp.
3. Let the milky liquid stand. The starch settles as a dense white layer within hours; pour off the water above it.
4. Re-suspend in clean water and settle again, two or three times. Each wash removes more protein and colour, and this is what separates usable starch from grey paste that rots.
5. Dry the cake gently, in air or very low heat, then break it up.

Uses:

• Sizing for paper — the East Asian method, and it stops ink feathering.
• Textile sizing — stiffens warp threads so they survive weaving, and starching linen is the same idea applied to finished cloth. See textiles.
• Paste adhesive — cook a thin starch-and-water mix into a translucent gel. It is weak compared with animal glue, but it is cheap, and it re-softens with water, which makes it the right choice for paper and book repairs you may want to reverse.
• Thickener in cooking, and a dusting powder.

Part 2: Pectin

Sources: apple pomace (the pressed residue from cider making), crab apples, quince, citrus peel and pith, unripe fruit generally. Ripeness matters — pectin degrades as fruit ripens, which is why jam made from very ripe fruit will not set.

Extraction: simmer the material in water with a little acid (vinegar or lemon) for around 30–45 minutes, strain through cloth without squeezing (which pushes cloudiness through), and reduce the liquid gently until it thickens.

A simple field test: add a spoonful of the cooled extract to a spoonful of strong spirit. A pectin-rich extract forms a single firm clot; a weak one forms scattered flecks. That tells you whether it will set a batch of jam before you commit the fruit and sugar.

Use: setting jams and preserves — see food preservation.

Part 3: Gelatin, glue, and isinglass

All three are collagen, differing mainly in purity and source.

Gelatin and hide glue — simmer hides, trimmings, hooves, sinew, or crushed bone in water for many hours, skimming continuously. Strain, then chill; a good extract sets to a jelly. Dry it in thin sheets or cakes and it keeps for years, reconstituted with warm water when needed. Construction detail is in woodworking and joinery; its use as a paper size is in paper.

Isinglass — from the swim bladders of fish, particularly sturgeon and cod. Clean, dry, and shred the bladder, then soak and dissolve it slowly in warm water or dilute acid. It gives the purest and most transparent of these materials.

Two uses worth knowing, because nothing else in this repository does them as well:

• Fining. Added to beer or wine, isinglass binds suspended yeast and haze and drags it to the bottom, leaving the liquid bright. Egg white does a similar job for wine.
• Transparent adhesive and consolidant. Nearly invisible when dry, which is why it was used for repairing parchment, vellum, and paintings.

Part 4: Acids and salts from fermentation

Cream of tartar — free, from the wine cask

As wine ferments and ages, potassium bitartrate becomes less soluble and crystallizes as a hard reddish or greyish crust on the inside of the cask and under the lees. This crude deposit is argol, and it is simply scraped off.

To purify: dissolve the crude argol in hot water, filter off the insoluble dirt and colouring matter through cloth (traditionally with a little clay or charcoal to adsorb the colour), and let it cool. Purified crystals form as the solution cools, because the salt is far less soluble cold than hot — the same recrystallization logic as salt and saltpeter. Repeat for whiter product.

Uses:

• A leavening acid. Combined with an alkaline carbonate it produces carbon dioxide in a dough without waiting for yeast — the principle behind chemical leavening. See bread and beer.
• A mordant in dyeing, especially with cochineal, where it brightens the colour. See dyes and ink.
• Cleaning and pickling brass and copper, because it dissolves the oxide. See copper and bronze.
• The raw material for tartaric acid, if you have stronger reagents.

Citric and lactic acid

Citric — from citrus juice. The classical purification is to precipitate it as insoluble calcium citrate with lime, wash the precipitate, and then release the acid again by treating it with a stronger acid, which in practice means sulfuric. Without that, concentrated lemon juice is a perfectly serviceable weak acid for most purposes.

Lactic — produced wherever vegetables or milk ferment. Rarely worth isolating; usually you want it in the food. See food preservation and dairy.

Acetic — see basic chemicals.

Part 5: Essential oils and aromatics

A high-value, low-bulk product from flowers, herbs, and peel — historically among the most profitable things a small operation could make, and the reason distillation apparatus existed long before anyone distilled alcohol with it.

Steam distillation. Pack plant material into a still with water beneath it, or pass steam through it. Volatile aromatic compounds travel with the steam, condense in the receiver, and — because most are only slightly soluble — separate as a thin oil layer floating on the water. Draw off the oil; the aromatic water beneath is hydrosol (rosewater, orange-flower water), which is itself a saleable product and should not be thrown away.

Good candidates: lavender, rosemary, mint, thyme, rose, and citrus peel. Yields are very low — commonly a fraction of a percent by weight of plant material, and rose is notoriously worse — so plan around processing a large volume of flowers for a small volume of oil.

Other methods:

• Expression — citrus peel oil is in surface glands and can simply be pressed or scraped out cold, with no heat at all.
• Enfleurage — for delicate flowers whose scent is destroyed by heat, such as jasmine. Spread purified fat on a sheet, lay fresh blossoms on it, replace them repeatedly over days as the fat absorbs the scent, then wash the scented fat with spirit to extract the perfume. Slow and material-hungry, and it captures scents distillation cannot.
• Tincture — steep material in distilled spirit. Simplest of all.

Essential oils are concentrated and are not gentle because they are natural. They are far stronger than the plant they came from. Many are skin sensitizers or irritants, several are phototoxic (bergamot and other citrus oils can cause severe burns on sun-exposed skin), and a number are seriously toxic if swallowed — wintergreen, pennyroyal, camphor, and eucalyptus have all caused poisonings, including fatal ones in small children. Do not treat them as medicine to be taken internally, keep them away from children, and dilute heavily for any skin contact. Distillation apparatus also carries the fire and pressure hazards described in whiskey and spirits.

Part 6: Saponins — washing without fat

Soap costs you fat, and fat is food. Several plants contain saponins, which foam and lift dirt in water without any fat at all: soapwort root and leaf, soap nuts (Sapindus), yucca root, horse chestnut, and ivy leaves.

Method: simmer or steep the crushed material in water and strain. Use the liquid directly.

Limits, honestly: saponin washes are mild. They lift dirt but cut grease poorly compared with true soap, so they suit delicate textiles, wool, and laundering more than they suit degreasing. They are also toxic to fish — which is exactly why some of the same plants were used as fish poisons — so do not discharge quantities of the liquor into a pond or a small stream, and some people find them irritating to skin and eyes.

Part 7: Fungi as a material

Nearly absent from this repository until now, and genuinely useful beyond food.

• Amadou, from the tinder fungus Fomes fomentarius. The soft inner layer is cut out, soaked (traditionally in a wood-ash lye or with saltpetre for tinder use), then beaten and stretched repeatedly into a soft, suede-like sheet. It takes a spark far better than almost anything else — see fire and heat — and the same worked material has been made into caps, bags, and clothing in parts of central Europe.
• Dye fungi. Several polypores and Cortinarius species give strong yellows, oranges, browns, and purples with an alum mordant. A real and underused dye source; see dyes and ink.
• Cultured moulds and yeasts. The most valuable fungal materials in this repository are already covered: koji for sake and soy sauce, brewing and baking yeast in bread and beer, and blue moulds in cheese.
• Vegetable rennet from flowers. Cardoon and thistle flowers coagulate milk — see dairy and cheese.

Fungal identification is species-specific and errors are dangerous. Several deadly species resemble edible or useful ones, and a fungus safe to handle is not necessarily safe to burn, eat, or apply to skin. Get identification from someone competent for your region, and do not use fungal preparations medicinally on the strength of a historical mention. See the foraging warnings in hunting, fishing, and wild food.

Part 8: Structural, abrasive, and container materials

• Gourds. Grow, ripen fully on the vine, then dry for months until the seeds rattle and the shell hardens. Cut, scrape out the interior, and you have a waterproof vessel that needed no kiln, no fuel, and no clay: bottles, scoops, bowls, spoons, floats for nets, and instrument resonators. One of the best effort-to-value ratios available.
• Horsetail (Equisetum), sometimes sold as Dutch rush. The stems accumulate silica and were used dried, in bundles or split flat, as a fine abrasive for finishing wood, horn, and soft metal — a natural fine-grit paper. Useful alongside the abrasive progression in precision and toolmaking and optics.
• Nutshells and fruit stones. Burned in a closed vessel they give a very fine, dense charcoal; crushed, they make a mild abrasive and a scouring material.
• Straw, husks, reeds, and corn cobs. Thatch, matting, basketry, packing, scouring, animal bedding, plaster and cob reinforcement, and fibre for paper.
• Bark. Birch bark peels into waterproof sheets for containers and yields tar (fire and heat); oak bark is the tannin source for leather; lime bast gives cordage fibre (textiles); cork is a float and a stopper.

Part 9: Animal by-products, briefly

Same logic, different waste stream. Most are covered elsewhere and collected here so the pattern is visible:

• Horn — soften with heat and water, press flat, and split into translucent sheets for lantern panes and windows; also combs, spoons, cups, and containers.
• Bone — buttons, needles (clothing), calcined to bone ash for cupellation (silver), and charred to bone char for decolorizing sugar.
• Eggshell — a calcium source, and egg white is both a wine fining agent and the binder in tempera paint (dyes and ink).
• Seashell — the purest and easiest carbonate source for burning lime.
• Whey — pig feed, ricotta, and a fermented drink (dairy).
• Feathers, sinew, hooves, and hair — fletching and quills, thread and cordage, glue, and plaster reinforcement.

Failure modes

Safety

• Essential oils: concentrated, variably toxic, phototoxic in some cases, and a common cause of poisoning in small children. Not for internal use.
• Fungi: identification is species-specific and mistakes can be fatal.
• Cassava and other toxic starch sources must be fully processed before any food use.
• Saponins irritate skin and eyes and are toxic to aquatic life.
• Distillation carries fire and pressure hazards; see whiskey and spirits.
• Vessels: no lead, and tin the inside of copper for anything acidic — several processes here are deliberately acidic. See silver and copper and bronze.
• Animal by-products carry the carcass-handling cautions in animal husbandry and leather and tanning, including anthrax risk from animals that died of unknown causes.

Era notes

Starch, glue, and plant washes are ancient and widely attested. Gourds are among the earliest domesticated plants, cultivated as containers rather than as food. Amadou use for tinder is prehistoric — the Iceman carried Fomes fomentarius — and worked amadou textiles are a documented central European craft. Argol was a recognized article of trade from wine regions in the medieval period, and Scheele isolated tartaric acid from it in 1769 and citric acid from lemon juice in 1784. Distilled aromatic waters were produced in the Islamic world well before alcohol distillation, and enfleurage is associated with the later French perfume industry. Isinglass was long used for fining and as a fine adhesive.

Your knowledge advantages here are mostly about noticing: that the crust in the wine cask is a useful chemical, that cider pomace holds the pectin, that hooves and swim bladders are adhesives, that a fungus makes a textile, and that a dried gourd is a free waterproof vessel. Also the spirit test for pectin strength, repeated washing as the thing that makes starch keep, recrystallization for purity, and knowing that essential oil yields are inherently tiny so you plan volume accordingly rather than concluding you did it wrong.

Sources and limits

Plant and fungal identification, foraging law, food safety, and the toxicology of concentrated plant extracts are specialist areas; this guide is historical orientation and not an identification key, a herbal-medicine reference, or clinical advice. Essential oils in particular should not be used therapeutically on the strength of a historical mention. Yields, concentrations, and dates here are approximate and not yet individually cited — see the coverage note in SOURCES.md.