microbes in food and beverage industry Flashcards
1
Q
microbes in food can be important sources of
A
proteins, vitamins and minerals
*single celled algae and cyanobacteria are used as food supplements
2
Q
describe edible fungi
A
- includes compost gorwn Agaricus bisporus: button and portobello mushrooms, gorwn int he dark on horse or chicken manure
- soem fungi are grown by inoculating spawn into logs of wood: shiitake, oyster and enoki mushrooms
- edible mushrooms are very hihg in protein (up to 25% dry weigh, simailr to milk) and include all the essential amino acids
3
Q
describe edible algae
A
- several types cultlivated, most notably in Japan
- red alga Porphyra form large multicellular fronds cultured for Nori - can be toasted in sheets and used to wrap sushi
- carbohydrate active enzymes made by the gut microbiota help to process carbohydrates to provide calories for the host
- research suggest that the genes for the enzymes come from transfer of porphyranase genes to gut microbiotia of poeple who traditionally eat a lot of nori
- porphyranases were identical to those of the marine microbe Zabellia galactanivorans
4
Q
describe giant kelp
A
- marcrocystic pyrifera is farmed for alginate
- alginate is a carboxylated polysaccharide
- used for many commercial purposes and as a gelling/thickening agent
5
Q
describe edible bacteria and yeasts
A
- most single celled microbes cannot be eaten, they contain large amount of nucleic acids
- purines -> uric acid cannot be oxidized, it crystalizes and causes health problems
- exception is spirulina, a marine cyanobacterium with low purine content, its rich in B12, protein and minerals
- other kinda of single celled proteins include eukaryotes like Saccharomyces cerevisiae (Baker’s yeastt & yeast extracts) and Candida albicans
6
Q
what is the purpose of food fermentation
A
- to preserve food by limiting microbial growth
- fermentation prodcuts limit growth of microbes and preserve food
- to improve digestibiltiy by breakign down fibers, fibrous macromolecules in meat and vegetables can be broken down by microbial action
- to add nutrients (liek vitamins) and flavour moecules (esters and sulfur compounds), fermenting microbes make vitamins as well as particular odiferous compounds that generate flavour
7
Q
microbial metabolism and food
A
- before industrial revolution all food contained live organisms
- in most cases this contamination would eventually spoil food, but humans discovered chemical and physical methods of preservation to retard microbial growth (salting, smoking and drying)
- in some bases microbial metabolism found to imrpove flavour and was embraced
8
Q
how are microbes used in fermented foods
A
depend on indigenous flora (found anturally in the food)
starter cultures (from a previous fermentation
- commerical food fermenting operations use highly engineered microbial strains to inoculate their cultures, although in some cases indigenous microbiota still participate
9
Q
describe industrial microbiology
A
commerical exploitation of microbes to benefit humans
- whole industries have sprung up to captialize on microbial metabolism, especally in food production
- many effrots are underway to characterize and imporve upon these microbial processes
- upstream and downstream processing mechansism allow large scale microbial production
10
Q
what is Kopi luwak
A
- asian palm civet naturally eats coffee beans that fall from trees to forrest floor
beans are digested and naturally fermented in animals gut
- civet cat feces are collected and the patially digested coffee beans are removed, dried and roatsed
very expensive
11
Q
what are the major classes of fermentation reactions
A
- homolactic acid fermentation
- propionic acid fermentation
- heterolactic acid fermentation
- ethanolic fermentation
- alkaline fermentation
12
Q
major chemical converstions in fermented foods
A
- usually starts out as carbohydrates or proteins
carbs -> glucose -> pyruvate then undergoes homolactic fermentation, propionic acid fermentation, heterolactic fermentation or ethanolic fermentation
- Proteins -> amino acids -> pyruvate then same as above to alkaline fermentation
13
Q
acid and alkali fermented foods
A
- many fermentations produce acids or bases
- an acid or base serves as an effective preservative
- the pH change is unliekly to be reversed
- animal or plant bodies at near neutral pH are unliekly to support gorwth of acidophiles or alkaliphiles which grow at extreame pH conditions
14
Q
acid fermentation of dairy products
A
- milk fermentation begins by lactic acid fermentation with lactobacillus and streptococcus
- pathways of fermenation are just eh major ones, there are thousands of secondary and minor fermentations that occur giving rise to potentent flavours
- dairy products primarily undergo acetic acid fermention
15
Q
actions resulting in formation of cheese curds
A
- proteolysis by enzymes (rennet)
- acidifcation (through fermentation fo lactose to lactic acid by microbes such as lactobacilus spp
