Lecture 18 Flashcards
What is the result of acid fermentation upon vegetable?
removes harmful microbes
What is pickling?
acid fermentation of vegetables in high salt brine
What are some aspects cocoa bean fermentation?
must take place close to harvesting, involves anaerobic fermentation by yeast, anaerobic fermentation by lactic acid bacteria, and aerobic fermentation by acetobacter species
What is the process after cocoa bean fermentation to get chocolate?
beans are dried and roasted, cocoa liquor and butter is extracted and sugar is added
What are theobromine and 2-phenylethylamine?
psychoactive products of cocoa fermentation
What is ethanolnic bread and wine fermentation?
converts pyruvate to ethanol and carbon dioxide, performed by yeast, CO2 causes bread to rise, ethanol is removed when baking
Why do we get off-flavours in alcohol?
pyruvate produces acetaldehyde which produces diacetyl
How do we achieve desirable flavours in alcohol?
pryuvate produces acetyl coA which then produces esters
What determines the difference between red and white wine?
wine derives from alcoholic fermentation of grapes, in white wine the skin is removed by not in red
Why is red wine fermented at a higher temperature than white?
to get the dark colour from the grapes into the wine before the skin is removed
What do different microbial changes produce in food spoilage?
acid - sour
oxidation of fats - rancidity
decomposition of proteins - putrefaction
alkalinity - bitter taste
What does food contamination/poisoning refer to?
the presence of microbes
What does food intoxication refer to?
ingestion of bacteria growing in food (toxins)
What causes dairy produces to taste sour?
excessive fermentation
What causes dairy products to taste bitter?
bacterial proteolysis
