microbes in food and beverage industry pt 2 Flashcards
whats biocontrol
A method of introducing an agent organism into a new ecosystem to naturally prey on and suppress target “pest” organisms.
agent = newly introduced
describe acid fermantation of dairy products
milk fermentation ebings with laciid acid fermentation with lactobacillus and streptococcus
acid fermentation of vegetables
- many vegetable products based on microbial fermentation
soybeans: microbes remove harmful elements, mold in rhizopus (tempeh) and asperhillus (miso, soy sauce) - cabbage, cucmbers and olives: pickling fermentation in brine (high salt) with bacterium eluconostoc mesenteroides
describe alkaline fermented foods
- ferment protens
- natto and pidan are products of alkaline fermentation
- bacillus breaks fownt he ‘bad’ components of soybean to make mroe digetable - get a stringy mass of polyglutamic acid
- Bacillus transforms duck eggs to gelatinous delicacy
describe fermentation of cocoabean to make chocoalte
- no starter culture has been commercialized and fermentation must take place geographically close to harvesting
- fermentation by indigenous microbes involves 3 successive stages
- after fermentation and pulp drainage beans are dried and raosted
- cocoa liquor and butter are extracted frmo beans and recombines with sugar and other stuff to make cocoamass
what are the 3 successive stages of cocoa fermentation
- anerobic fermentation by yeast
- anaerobic fermentation by lactib acid bacteria
- aerobic fermentation by acetobacter species
why cant dogs eat chcolate
contains theobromine and 2 phenylethylamine - psychoactive products of cocoa fermentation
- dogs metabolize theobromine very slow and can be toxic to them
what is responsible for fermentation of bread and wine
ethanolic fermentation by saccharomyces cerevisiae (yeast)
- convers pyruvate to ethanol and CO2, CO2 is the leavening agent in bread
yeast bread vs sourdough
- bread dough is leavened by microbial CO2
- yeast: requires extensive kneading of gluten rich flour to make network of holes for CO2 to be released
Sourdough: as well as bakers yeast uses a cutlure of undefined lactobacillus sp[
whats injera
- ethiopian bread
bade by teff, grain with no gluten
- dough requires prolonged fermentation with extensiev/complex microbial activity
- makes an adible “clothe”
- fermentation dominated by yeast candida
what micrbo used for beer
– saccharomyces cerevisiae
- beer derives from alcoholic fermentation of grain
- barley grains are germinated, allowing enzymes to break down the starch into maltose for yeast fermentation
- secondary products like long chian alc and esters generate the flavours
**excess diacteyl gives off the flavours
what type of fermentation does wine undergo
malolactic by oenococcus oeni bacteria
what are causes food spoilage
- microbial chanegs that render a product unit or unpalatable for consumption
- actis -> sour taste
Oxidation of fats -> rancidity
Decomposition of proteins -> putrification
alklainity -> bitter taste
food contmaination vs intoxication
food contamination (food poisoning) refers to presence of human pathogens
food intoxication refers to the ignestion of toxins in food (produced from/by bacteria growing in food)
how do the following spoil: dairy, meat, seafood, plants
Dairy: soured by excessive fermentation or made bitter by bacterial proteolysis
meat: putrefied by decarboxylating bacteria producing amines with noxious odors
seafoods: spoil rapidly bc of unsaturated fatty acids rapidly oxidize
*psychotrophic bacteria reduce trimethylamine oxidase to the fishy smelling trimethyl amine
- plants spoil by excessive bacterial or mold gorth- pathogens can destroy food crops ebfore harvest
