Fermentation

Ethnobotany? Botany includes the study of plants and other living things that were previously considered to be plants – fungi (including yeasts) – bacteria and archaea Substrates include plant-based foods and others

Merriam-Webster’s Collegiate Dictionary: FERMENTATION: (a) a chemical change with effervescence (b) an enzymatically controlled anaerobic breakdown of an energy-rich compound (as a carbohydrate to carbon-dioxide and alcohol or to an organic acid); broadly: an enzymatically controlled transformation of an organic compound.

pathway of fermentation Figure from Raven, et al. “Biology of Plants”

Advantages of fermentation Why do cultures around the world deliberately inoculate all kinds of foods with bacteria, yeasts, or other fungi to facilitate fermentation?

Advantages of fermentation prevent spoilage (most of world without refrigeration) reduce transmission of pathogenic organisms (acidity), reduce food poisoning (but not necessarily) improve digestibility – hydrolysis of proteins and lipids – texture (soybeans vs. tempe) – convert carbohydrates (may reduce those that cause flatulence) changes in color, odor, flavor, texture nutritional quality – increase B vitamins (but goes both ways depending…) – decrease phytic acid (anti-nutritional)  make minerals more available meat-like substitutes (e.g., textured soy protein) production of compounds – antibiotics, vinegar, citric acid, alcohol

Substrates and examples Legumes (soybeans, peanuts, other beans) Vegetables and Fruits (sauerkraut, etc.) Milk and dairy products Grains (breads, alcoholic beverages) Meats, fish sauces, fat you name it…

Tempeh

Legumes tempe - Originated in Indonesia (probably Java) – soybeans and molds (especially Rhizopus oligosporus) – Many nutrients increase, some decrease: increase in tryptophan, alanine, 2  riboflavin, 7  niacin, 33  vitamin B12 (Good vegan source of B12!) but decrease pantothenate, thiamine, lysine, methionine, phenylalanine – more digestible as enzymes break down proteins

Legumes soy sauce, tamari, shoyu (originated in China) – soy beans, wheat fermented months – Aspergillus soyae or A. oryzae – 45 hours: control temperature, moisture, aeration – Pediococcus soyae and Saccharomyces rouxii – high salt for 1-3 years

Vegetables and Fruits – sauerkraut: sequence of bacteria depends on salt concentration, temperature, sanitation early stages: bacteria Leuconostoc mesenteroides (same as found in olives, sugarbeets, coffee, and silage!) later stages: Lactobacillus brevis, L. plantarum but at high temps other microbes may cause spoilage improper mixing of salt – pink yeasts and soft sauerkraut – kimchee: less acid, carbonated decrease in pathogenic bacteria, intestinal parasites increase in B vitamins sauerkraut, kimchee, pickles

Milk and dairy products (buttermilk, cheese, yogurt, kefir and koumiss) un-pasteurized milk is naturally inoculated with lactobacilli and streptococci, which curdle milk and protect it from spoiling lactose converted to lactic acid, preserves by acidity, more digestible for those who are lactose-intolerant content of acid and/or alcohol depends on temperature, inoculum yogurt: bacterial cultures (Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus acidophilus) cheese: the above and other spp. Lactobacillus, Lactococcus lactis, Leuconostoc mesenteroides, plus molds to develop flavor Penicillium roquefortii, P. camambertii, etc. many are probiotics…

Probiotics Probiotics have been defined as live microorganisms that confer a health effect on the host when consumed in adequate amounts (Guarner and Schaafsma 1998). Oversimplified explanation: Antibiotics create “open niches” in intestinal flora that give “bad” bacteria an opening. Probiotics help the “good” bacteria fight off the bad ones. Kefir “grains”  – Kefir cultures are symbiosis of bacteria and yeast together (several kinds of each) – microbes can colonize gut image source: A. Kniesel on Wikipedia

anticancer, antidiarrheal, antihypertensive vitamin content changes (B & E) stimulate immune system mineral absorption cholesterol Health effects of culture-containing dairy products

In addition to helping with lactose intolerance: Lactic Acid Bacteria (LAB) treat gastrointestinal infections prevent and treat diarrhea other problems: gastritis, irritable bowel, radiotherapy side effects, constipation cancer prevention

Grains (breads and pancakes) yeast bread Saccharomyces cerevisiae – Same yeast as beer sourdough and rye bread – symbiotic relationship – mixed culture of yeast and lactic acid bacteria – a different yeast: Torulopsis holmii (now Candida milleri) – Lactobacillus spp. (including Lb. sanfranciscensis) convert maltose to glucose image source: Chris R. Sims on Wikipedia

Injera/Enjera a spongelike pancake eaten with stews very important food in Ethiopia tef Eragrostis tef batter fermented by various yeasts, bacteria, and fungi (complex mixture of microbes) changes in microbes as pH is reduced over 2 days of fermentation reduce phytic acid  improves availability of minerals such as zinc

Alcohol fermentation: beer, wine, distillates “primitive” wines and beers not “crystal-clear” but rather “cloudy, effervescent slurries, containing residues of the substrates and the fermenting yeasts and other microorganisms… provide not only calories but also B vitamins as well” (Steinkraus, 1983) primary brewing and baking yeast is Saccharomyces cerevisiae

Alcohol fermentation carbohydrate  simple sugars  ethanol at least back to 5400 BC, probably further wine 1 st, then beer? – spontaneous fermentation vs innoculated

Drinking beer out of straws (to avoid the grain hulls and beer solids) in ancient Mesopotamia slide from Cathy Vrentas

Hymn to Ninkasi—Recipe for Sumerian Beer (1800 BCE) You are the one who handles the dough, [and] with a big shovel, Mixing in a pit, the bappir with sweet aromatics, Ninkasi, You are the one who handles the dough, [and] with a big shovel, Mixing in a pit, the bappir with [date]-honey. You are the one who bakes the bappir in the big oven, Puts in order the piles of hulled grains, Ninkasi, you are the one who bakes the bappir in the big oven, Puts in order the piles of hulled grains, You are the one who waters the malt set on the ground, The noble dogs keep away even the potentates, Ninkasi, you are the one who waters the malt set on the ground, The noble dogs keep away even the potentates. Anchor Brewing Sumerian Beer Project You are the one who soaks the malt in a jar The waves rise, the waves fall. Ninkasi, you are the one who soaks the malt in a jar The waves rise, the waves fall. You are the one who spreads the cooked mash on large reed mats, Coolness overcomes. Ninkasi, you are the one who spreads the cooked mash on large reed mats, Coolness overcomes. You are the one who holds with both hands the great sweet wort, Brewing [it] with honey and wine (You the sweet wort to the vessel) Ninkasi, (...) (You the sweet wort to the vessel) slide from Cathy Vrentas

Yeast in Beer—Discovered by Louis Pasteur in 1871 Top-fermenting yeasts—Ales. Fermented at warmer temperatures. Bottom-fermenting yeasts—Lagers. Fermented at colder temperatures by yeast that sink to the bottom of the tank, then let to sit at cold temps for at least a month to mellow flavors. Lambic Beers—From Belgium—Fermented by a mix of wild yeast and bacteria to create a tart taste. Often, fruit is added (Framboise—Raspberry; Kreik—Cherry). slide from Cathy Vrentas

History of Beer Production --Fermented grain beverages produced since Prehistoric times, including documented evidence of Babylonian recipes for beer; strong presence in Egyptian culture --Wild yeasts in the air could spontaneously ferment domesticated cereal grains --Different cultures used different grains: Millet, corn, rye, sorghum, barley --Wine became more important than beer in civilizations like the Roman Republic and Empire—but beer remained important in many areas --In Medieval times, much production shifted to centralized sources—monasteries and convents to provide beer for traveling pilgrims --Beer was brewed in Sir Walter Raleigh’s colony in Virginia in 1587 slide from Cathy Vrentas