Fermentation
what are the four microorganisms involved in fermented foods
LAB, other bacteria (Propionibacterium, Brevibacterium), fungi, yeast
how does natural fermentation occur and what are ex
relies on indiginous organisms-wines, saurkraut, kimchi, soy suace
what is backslopping and what are ex
relies on use of previous batch-sausge, sour dough, beer, keifer
what is the yeast in bakers yeast
saccharomyces cervisiae
what are thermophilic cultures (3)
streptococcus thermophilus and lactobacillus helvecticus or lactobaccilus delbruekii subsp: bulgaricus
the ecological phenomenon that occurs in fermented foods when one group of organisms creates an environment that promotes another group is called?
succession
what do we study to understand biochemical phenotype (3)
sugar fermentation patterns; catalase, oxidase, urease; metabolic end products
what aromas and flavors do the cultures in smear cheeses give off
sulfury
why is taxonomy important in fermentation microbiology (2)
tells us what organisms performed the fermentation and what organisms can be added to enhance the product
what does the successful manufacture of fermented foods ultimately rely on
the performance of the microorganisms
what is a challenge for brewing
the substrates (cereal grains) contain little or no sugars, but lots of starch so the starch must be converted to fermentable sugar
what is the culture in swiss cheese (2)
thermophilic lactic acid bacteria and propionibacterium freudenreuchuu subsp. shermanii
what type of cultures must be used in hard-grating cheeses and why
thermophilic since high cooking temperature
why do we add water to washed cheese curds
to dilute out lactose, resulting in less acid formed during fermentation
why are hard cheeses cooked to a high temperature
to drive our moisture
what is the purpose of malting
to provide a stable source of enzymes and substrates
what products contain tetragenococcus
veg
what are examples of cultured dairy products
yogurt, buttermilk, sour cream, kefir
what are the two fermentative pathways for lactose
homofermentative, heterofermentative
what is the specialized flavor in cultured dairy (2)
1. acetaldehyde (tart apple flavor in yogurt) 2. diacetyl (buttery) in buttermilk and sour cream
what are the 3 basic steps to dairy fermentation
1. acidification 2. enzymatic 3. heat +acid
what are the 4 steps of malting
1. barley 2. steeping and germination 3. drying and kilning 4. malt
what are the steps of post-fermentation (4)
1. beer 2. clarification and filtration 3. packaging and pasteruization 4. beer
what are the 4 current issues in the starter culture industry
1. biomass, stability, viability 2. biopreservation 3. customized properties (flavor, texture) 4. phage-viruses that infect bacteria
what are the 2 types of cultures
1. bulk cultures (lyophilized or frozen) 2. direct-to-vat cultures (lyophilized or frozen)
what are washed curd cheeses (4)
1. colby 2. monterey jack 3. havarti 4. dutch cheeses (gouda, edam)
what are the general properties of fermented foods (6)
1. enhanced preservation 2. enhanced nutritional value 3. enhanced functionality 4. enhanced organoleptic properties 5. unique 6. increased economic value
what is required in swiss cheese to get perfect eye formation (3)
1. exact texture (soft and elastic) 2. 35% moisture 3. pH 2.5
what are the general functions of LAB in fermented foods (5)
1. ferment sugars and reduce pH 2. sythesis of flavor compounds 3. texture changes 4. out-compete other microbes 5. production of antimicrobial substances
what are the desirable properties of bakers yeast (7)
1. gassing power 2. flavor development 3. ethanol tolerant 4. cryotolerant 5. stable to drying 6. stable to storage 7. easy to dispense
why do we not like backslopping and natural fermentations in sausage (5)
1. inconsistent quality 2. unreliable fermentation 3. long fermentation times 4. risky for food safety 5. difficult to control
what are the 4 principles of cultured dairy
1. isoelectric precipitation 2. no whey removal 3. minimize syneresis (whey removal) 4. specialized flavor department
what are the steps of wort preparation (9)
1. malt 2. milling 3. add water and adjuncts 4. mashing 5. lautering 6. kettle boil 7. add hops 8. whirlpool 9. wort
what are the four steps of beer fermentation
1. malting 2. wort preparation 3. fermentation 4. post-fermentation
what are the 3 ways to initiate sausage fermentation
1. natural fermentation 2. backslopping 3. starter culture
what are the three ways to initiate fermentation
1. natural fermentation 2. backslopping 3. starter cultures
what are the prinicples of fermented vegetables (5)
1. natural fermentation-no culture necessary 2. relies on autocthonous organisms 3. requires selection for LAB and against everything else 4. microbes grow in succession 5. leave raw or heat-treat finish product
what are 5 methods to prevent phage problems
1. plant design 2. sanitation 3. phage inhibitory media 4. culture rotation 5. phage resistant cultures
what are four functional properties of sour dough cultures
1. preservation 2. production of anti-fungal agents 3. flavor 4. reduced staling rate
what are the functions of starter cultures in sausage fermentation (6)
1. produce lactic acid and lower the pH 2. flavor 3. out-compete pathogens 4. growth depends on added carbs 5. culture growth lowers Eh 6. for european style sausages nitrate is used instead of nitrite and non-LAB are needed to redice it to nitirite-producing flavor and color
what are the 4 principles of cheese
1. remove water 2. flavor and texture development 3. concentrate protein and fat 4. long shelf-life
what are the 4 nutritional requirements of LAB
1. sugars for energy 2. pre-formed amino acids 3. complex nutrients (some strains) 4. anaerobics (some strains)
why do we need starter cultures (5)
1. volume/density 2. convenience 3. timeliness 4. consistency 5. novel traits
what are the steps of fermentation (6)
1. wort 2. cool 3. add pitch 4. fermentation 5. conditioning and maturation 6. beer
what are the requirements for the bacteria and yeasts for sour dough fermentation (3)
1. yeast must be acid tolerant 2. bacteria must be ethanol tolerant 3. must not compete for the same sugars
what percent of probiotic products contain Lactobacillus
>80%
what are molecular approaches for identification that are good at the species level (3)
DNA-DNA hybridization, 16s rRNA sequencing, whole genome sequencing
what are common characteristics of LAB
G+ rods and cocci, non-spore forming, catalase negative, non-motile, fermentative, facultative anaerobes, acid-tolerant
what are molecular approaches for distinguishing between strains (4)
Random amplification of polymorphic DNA (RAPD), multilocus sequence typing (MLST), pulsed field gel electrophoresis (PFGE), amplified fragment length polymorphism (AFLP)
what is acidification
adding casein, the main milk protein precipitates or coagulates at pH 4.6-4.7
what does blue cheese require for interior mold growth
aeration
what causes the amylose and amylopectin reaction
alpha-amylase
what is the enzymatic step in dairy products
casein also coagulates after treatment with the enzyme chymosin
what is the heat + acid step in dairy fermentation
casein precipitates at high temperatures
what does malt affect
color, body, flavor
What is a starter culture?
concentrated and preserved source of selected microbes that are added to raw or pasteurized substrates to overwhelm the resident organisms and perform the desired fermentation on a reliable, predictable, consistent basis
how can phage resistant cultures prevent phage problems
construct starter culture cells that will grow and perform well even in presence of phage
what is cheese ripening
controlled spoilage
what is malting
conversion of barely to malt
what products is lactococcus found in
dairy
what products is streptococcus found in
dairy
what products are lactobacillaceae found in (most important to know)
dairy, meat, veg, fruit/wine
what products is leuconostoc found in
dairy, veg, fruit/wine
what are starter cultures and what are example products
defined strains in concentrated form-cheese, yogurt, sausage, wine, beer, bread
how are starches converted to sugars
enzymatically, using enzymes synthesized in the barley, acting on substrates in the barley
what does cheese ripening cause changes in (4)
flavor, texture, appearance, rheology
what products is Oenococcus found in
fruit/wine
what do we study to understand morphology (3)
gram reaction, motility, spore formation
what does brie require on the surface
growth by mold
what do we study to understand physiology and ecoloy (3)
growth temperature, pH range, aerobic or anaerobic
what do the cultures in smear cheeses cause on the surface
growth with orange-red pigment
what fermentation path is sour dough
heterofermentative
what are the 2 fermentative pathways in lactic acid bacteria and generation of flavor compounds
homofermentative and heterofermentative
what is mashing
hydrolysis of starch and protein
what are other methods of analysis
immonogenic, cell wall structure, membrane lipids
why will changing a name for a major genus have a major impact on the probiotic and starter culture industry
it will improve sequence-based identification and avoid misidentification/miscommunication and provides a basis for connecting functions to specific species or groups
why do we need to ID strains
just in case another company steals your strain
how can plant design prevent phage problems
keep phage out of production area and prevent cross contamination
how can sanitation prevent phage problems
kill phage in plant environment
what 2 genera of lactic acid are used for meat starter cultures
lacotbacilliacea (favored at high temps) and pediococcus (favored at low temps)
what are the products are homofermentative
lactate
what is the product of the homofermentative pathway
lactate
what are the products of heterofermentative
lactate, acetate, CO2, ethanol
what is the products of the heterofermentative pathway
lactate, acetate, CO2, ethanol
what bacteria are used in brie (2)
lactococcus lactis and penicillium camemberti
what bacteria are used in blue cheese (2)
lactococcus lactis and penicillium roqueforti
what are mesophilic cultures (2)
lactococcus lactis subsp: lactis and/or lactococcus lactis subsp: cremoris
what are citrate-fermenting cultures
leuconostoc mesenteroides subsp. cremoris
what does the flavor in blue cheese come from (3)
lipolysis, fatty acid metabolism, and formation of methyl ketones
what does fermentation do to milk
makes a coagulated milk gel
what is the difference between spoilage and fermentation
matter of control-in fermentation conditions are controlled such that selected microbes grow
what products is pediococcus found in
meat, veg
what type of cultures do munster and other smear cheeses use
mesophilic
what type of cultures do washed curd cheeses use
mesophilic
what are the four traditional methods of analysis
morphology, biochemical phenotype, physiology and ecology, other
what is fermentation controlled by (7)
pH, mositure, substrate availability, temperature, salt, competition
what are examples of hard grating cheeses
parmesan, grana, asiago, romano
how can phage inhibitory media prevent phage problems
prevent phage from attaching to and infection culture cells
how can culture rotation prevent phage problems
prevent proliferation of phage by limiting access to suitable hosts
what is the flavor from in brie (2)
protein and fat metabolism (NH3)