Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
25 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
What are characteristics of lactic acid bacteria?
|
gram-positive
aerotolerent anaerobes Two types: Homofermentative Heterofermentative Used in fermented products (saurkraut, pickles) Lactic acid production reduces pH and improves storage quality |
|
|
|
Homofermentative
|
fermentation yields primarily lactic acid
used in PICKLES!!!!! |
|
|
|
Heterofermentative
|
fermentation produces lactic acid AND a variety of flavorful compounds
used in CHEEEEESE!!! |
|
|
|
What does lactic acid due to food?
|
reduces pH
increases shelf life |
|
|
|
What are yeast used for?
|
alcoholic beverages and breads
commonly use saccharomyces strains |
|
|
|
Whey
|
water in milk
|
|
|
|
casein
|
milk protein that causes thickening in yogurt and other milk products when DENATURED
|
|
|
|
What are the two main processes in making cheese?
|
curdling and Ripening
|
|
|
|
What is curdling? Process?
|
1) curdling is when lactic acid bacteria and/or Rennin precipitate proteins and fats == curd formation
starter culture ferments lactose to produce lactic acid 2) Whey is drained off and treated like sewage (cuz of high BOD) or used for other processes 3) Curd is heated to extract more whey 4) salt added to promote extraction of water and inhibit growth of unwanted organisms 5) Packing or Pressing and Ripening |
Rennin cleaves caesin, resulting in curd formation
|
|
|
What is Ripening?
|
leads to texture and flavor change due to organisms added in starter culture or added after onto surface
cheese is pressed and packed and allowed to age for long period of time Different methods for different cheeses |
|
|
|
How are hard cheeses ripened?
|
wrapped
no additional bacteria added to cheddar cheese Swiss - innocculated with propronibacter to produce bubbles longer you ripen-- the higher the acidity and sharpness |
|
|
|
What is the process of ripening in Semi-soft cheese (blue) ?
|
Curd is innoculated with penicillium roquefortti that creates blue spores in wholes
|
|
|
|
What is the ripening process if soft cheese (Brie) ?
|
Curd is left UNWRAPPED and additional bacteria is added to surface
bacteria excrete proteases that are responsible for softening Needs to be very sanitary |
|
|
|
Process of Making Vinegar?
Bacteria used? |
Use acetobacter-- STRICT AEROBE
oxidizes ETHONAL--> acetaldehyde --> ACETIC ACID oxidation produces pmf and ATP!! |
|
|
|
How is Wine made? Whats the difference between dry and sweet wine? red and white?
|
MUST (grape juice) used
Metabisulfide added to prevent growth of WILD yeast resistant yeast S. cervisia and S. elliposideus added and grow until 12-14% alcohol content Dry wine= all sugars fermented Sweet = sugars left or added Red= fermented with skins White= no skins |
|
|
|
Metabisulfide
|
Na2S2O2
added to wine to prevent growth of wild yeast |
|
|
|
What are the 5 steps of brewing??
|
1. malting
2. Mashing 3. Boiling 4. Fermentation 5. Polishing |
|
|
|
What is Malting
|
First step of brewing
grains are allowed to germinate producing amylase, amylase breaks down starch (cannot be digested by yeast) into fermentable sugars (activated in mashing) Grains are then dried and crushed to create MALT |
|
|
|
What is Mashing?
|
second step of brewing, after malting
malt is soaked in 60 C water for 1-2 hours to allow activation of amylase to convert starch into sugars ( glucose and maltose) that could be fermented malt is filtered to create WORT |
|
|
|
What is Boiling?
|
Third step of brewing, after mashing
HOPS is added to WORT and wort is boiled for several hours (NEAR STERILIZATION) Flavor and ANTIMICROBIAL compounds extracted from hops during boiling Hops prevents lactic acid bacteria from growing Filtered (commercial) and then cooled to 20 C |
|
|
|
What is Fermentation?
|
Fourth step of brewing, after Boiling
Yeast is added to wort- vary depending on type Lager = top yeast (saccharomyces carlsbergensis) Ale = bottom yeast (S. cerevissia) |
|
|
|
What are factors that effect taste during brewing?
|
malt source
hops yeast time and temp of fermentation |
|
|
|
What is polishing?
|
Last step of brewing, after fermentation
filtration, pasteurization and carbonation in bottle carbonation is when sugar is added before bottling and additional fermentation is carried out, which produces bubble! bubbles dissolve into liquid when under pressure |
|
|
|
How is light beer made?
|
with Genetically modified yeast that uses all sugar in wort
|
|
|
|
When and why is hops added to brew?
|
During boiling (3rd step)
added for taste and antimicrobial compounds that prevent the growth of lactic acid bacteria |
|
