Fermented Foods Test 2

Feta cheese

Low pH with demineralization lipase may be added rancid flavors desired very crumbly texture final pH 4.6-4.8, can add titanium dioxide to the milk

Buttermilk and sour cream cultures - acid and flavor producers

Acid - lactococcus lactis subspecies. lactis and or cremoris Flavor - leuconostoc lactis leuconostoc mesenteroides subspecies dextranicum or cremoris

What 3 ways can you do coagulation

Acidification to the isoelectric point (mostly soft or unripened cheeses like cottage cheese, cream cheese) Enzymatic hydrolysis of kappa-casein, followed by calcium-mediated coagulation (most hard cheeses like cheddar, swiss, parmesan) Acid + Heat (ricotta, whey cheeses)

What happens during cheddaring?

Acidification, syneresis, de-mineralization, gravity.

What do carbs in cheese produce and contribute to

Acids, alcohols, aldehydes, CO2 contributes to flavor

What is the specialized flavor development in yogurt? in buttermilk and sour cream?

Acetaldehyde in yogurt. Diacetyl in others

Cultured buttermilk quality of starter cultures

Rapid/vigorous growth produce the right body good flavor (Acid and diacetyl) no syneresis

Yogurt quality and defects with starter cultures

Rapid/vigorous growth produce the right body good flavor (acid and acetaldehyde) no syneresis or 'wheezing off' no excess acidity (over acidification)

Sour cream quality of starter cultures

Rapid/vigorous growth produce the right body good flavor (acid and diacetyl)

Milk starter for yogurt

Standardize (nonfat, low-fat or whole) nonfat milk solids (>11%). stabilizers and other ingredients.

cheese ripening Reactions affected by

Temperature, cheese composition, microorganism in the cheese

Trends in yogurt technology

Texture-enhanced (whipped, extra thick, custard), greek-style (Strained), fluid (drinks, smoothies), mild-flavored (especially low acid), probiotic/prebiotic, frozen

Issues in the cheese industry

Yield (Cheese as well as fat and protein) Bitterness Whey (Utilization of constituents) Bacteriophage Quality: Flavor, texture, color, crystals, mold, physical appearance

Cheese coagulated by chymosin

rely on kappa-casein on ca2+ mediated precipitation used for most cheese types fermentation is needed for flavor, preservation and function.

fermented cabbage

sauerkraut

Muenster short list

surface growth, with orange-red pigment, brevibacterium linens, sulfury flavors, US (milder) versions have little or no surface growth

What about the yogurt culture

symbiosis, synergism, mutualism, proto=cooperation bottom line- both grow better together than apart. have higher growth rates and cell densities and more end products produced. relevant ing YOGURT AND CHEESE Need ratio of 1:1 because influences final product

What is the isoelectric point?

the pH at which the net charge of a protein is zero. Or at it's isoelectric point a protein is at it's minimum solubility.

What happens upon the hydrolysis of kappa casein

the surface charge of the remaining micelle is dissipated, and the core subunits have greater access to calcium.

Overall goal about cheese manufacture

to control microbial, enzymatic and chemical reactions

What does l bulgaricus do for s thermophilus

Hydrolyzes protein, provides amino acids and peptides.

What does lactic acid break down into for swiss cheese fermentation

3 lactic acid goes to 2 propionic acid, 1 acetic acid and 1 CO2

HT for yogurt

85C for 30 minutes (90C for 15) or 95 for 8-10

4 main fractions of casein chemistry

Alpha s1, alpha s2, beta, kappa

Mozzarella cheese manufacture

Also relies on 'cheddaring' process, fermentation after cooking, then brine-salted pH 5.1-5.2 is critical for proper stretching

What do proteins in cheese produce and contribute to

Amines, peptides, NH3 Contributes to flavor and texture

Principles of isoelectric precipitation

Amino acids can either be neutral or they can carry negative or positive charges. these charges can cause electrostatic repulsion, which helps maintain protein in solution, as charge repulsion is dissipated, protein becomes less soluble and eventually it will precipitate.

Measuring cheese ripening

Analytical techniques, aka electronic noses (GC, GC-MS) Protein electrophoretic techniques (1 or 2-D) Soluble nitrogen, free fatty acid Sensory analysis

How can milk proteins be separated

By enzymatic means or via isoelectric precipitation

Role of calcium in cheese texture

Calcium-casein needed to maintain plasticity, lower the curd calcium, the more crumbly is the cheese, lower the pH, more calcium is lost, therefore, can influence texture by controlling calcium (de-mineralization)

Acid mediated coagulations

IF you add acid, the acid takes way available calcium ions which causes the structure to not bind as tightly

Casein chemistry

Casein refers to group of serveral different proteins. They are negatively charged due to presence of phosphate groups attached to serine residues

cheese ripening involves

Chemical reactions, enzymatic reactions and physical phenomenon -changes occur in flavor, texture, appearance, rheology

Cheese ripening enzymes from

lysed bacteria, milk, coagulant

mozzarella cheese: functional properties

Color (browning), stretch, oiling off, melting, spreadability, flavor

What is cheese ripening

Controlled spoilage

What determines the moisture content

Cooking/stirring

Cheese coagulated by chymosin factors that influence final product

Curd handling, acidification, salt, culture activity, shape and form and cook temperature

parmesan, grana, other hard grating cheeses

Dry, with hard rinds thermophilic cultures nutty, sharp, savory flavors

What is the take home message of EPS

Expression of EPS is complicated and obtaining consistent production can be challenging

What is the purpose of cooking cheddar cheese?

Firm the curds, enhance syneresis, and control culture activity.

Types of stabilizers in yogurt and cultured dairy products

Gelatin, starch (native and modified), pectin, gums (carrageenan, guar, alginate, locust bean), exopolysaccharides (EPS)

Accelerated ripening

Goal: achieve aged cheese flavor in less time Adjust temperature (from 8-10 to 12-18) add adjuncts add enzymes (EMC)

Citrate fermenting cheese culture

Leuconostoc lactis and other leuconostoc sp.

What are cheese types based on?

Hardness, acidification method, moisture content, cooking temperature, mode of ripening, extent of aging, and distinguishing characteristics

Cheese precipitated by acid + Heat methods

Heat can be via direct or indirect (steam infusion) Acidification is via sour whey or milk or food-grade acids Flavor is rather bland to slightly sweet, but usually have excellent functional properties (melting, slicing, mouth-feel, etc.)

Alpha s1 and s2 casein fractions

High negative charge charge, high phosphate content, and calcium-sensitive

Flavor compounds in cheese

Hundreds of compounds, some have very low thresholds (ppm) for flavor, A little may be good, too much is a defect for example, a little h2s in cheddar is desirable, but too much is a defect 2 ppm methyl ketone in cheddar is fine, and 90 ppm in blue is fine, but 90 ppm in cheddar is not so good

What are the main principles of cultured dairy products?

Isoelectric precipitation, no whey removal, minimize syneresis, and specialized flavor development

Yogurt quality and defects with flavor defects

Lack of flavor too much flavor poor flavor yeasty (from fruit) unclean, bitter (from milk)

Sour cream defects of starter cultures

Lacks flavor caused by not enough citrate fermenters, incubation temperature too high or too low, product too fresh (best after 72 h) Too much acid, harsh wheying off too thin (firmness very important) yeasty, unclean

Cultured buttermilk defects of starter cultures

Lacks flavor caused by not enough citrate fermenters, incubation temperature too high or too low, product too fresh (best after 72 h) Too much acid, harsh wheying off too viscous, too thin yeasty, unclean

Mesophilic dairy starter cultures

Lactococcus lactis subspecies lactis (and biovar diacetylactis) and lactococcus acties subsp cremoris

Mesophilic cheese cultures

Lactococcus lactis subspecies. lactis, lactococcus lactis subspecies. cremoris -used for medium cook cheeses

Growth of LAB in milk

Lactose is rapidly fermented, lactic acid is produced. at pH 4.9-5.2, casein becomes 'destabilized' and at 4.6-4.7 precipitation (coagulation) occurs Minimal protein degradation occurs in cultured products, much more important in cheese. other end-products important for flavor and texture.

Citrate-fermenting (for flavor) dairy starter cultures

Leuconostoc lactis Leuconostoc mesenteroides subspecies. cremoris Leuconostoc mesenteroides subspecies. dextranicum

What is annatto?

Natural coloring added to cheeses

Buttermilk and sour cream cultures - characteristics

Need an acid producer and flavor producer, too much or not enough acid inhibits flavor production, control managed by inoculum and incubation temperature, acid producer:flavor producer ratio about 5:1 to 6:1. incubation temperature 20-22C, higher temperatures favor lactococci (acid producer)

Yogurt texture and rheology - weak body

Not enough solids, insufficient heat treatment insufficient stabilizers

Yogurt texture and rheology - syneresis

Not enough solids, insufficient heat treatment, rough handling, high acidity

Kapa casin fraction

Quite different from other casein fractions, glycoprotein substrate for chymosin

Exopolysaccharides produced by LAB

Referred to as 'ropiness,' EPS provide important rheological and functional properties in food. capsular (attached to cell surface) or secreted Produced by thermophilic and mesophilic strains. chromosomal or plasmid-encoded production is not constitutive and is subject to growth phase, substrate availably and other factors Homopolysaccharide or heteropolysaccharide.

Cheddar cheese manufacture

Relies on 'cheddaring' process Fermentation after cooking, then dry-salted pH 5.1-5.2, 2.25% salt, 37-39% H2O, 50% fdb

Cheese precipitated by acid + Heat

Rely on high heat (>80C) and slightly acid (pH 5-6) Denatured whey proteins co-precipitate with casein Can use milk or whey Usually soft, fresh, unripened cheeses like ricotta, queso blanco and paneer.

Acid-precipitated cheese

Rely on isoelectric precipitation of casein most are unripened examples include: cottage cheese, cream cheese Can reach pH 4.6-4.7 one of two ways 1. fermentation and lactic acid formation 2. direct acidification by adding food grade acids (lactic, gluconic acid) (advantages is no culture preparation needed, faster, more convenient, but has lack of flavor, and labeling.

Principle of cheese manufacture

Remove water, concentrate protein and fat, flavor and texture development (via microbial, enzymatic, and physical-chemical reactions), long shelf life

Blue cheese

Requires aeration penicillium roqueforti flavor from lipolysis, fatty acid metabolism and formation of methyl ketones pH 4.5-4.5 after fermentation. pH 6.5 at the end of aging

Swiss cheese "easy to make, but difficult to make well"

Requires just the right texture, pH, and moisture to obtain perfect eye formation Too soft, too dry, too acidic, too sweet, all result in quality defects Therefore, need to control multiple variables to achieve a high quality product

Buttermilk

Rich in phospholipids and other natural emulsifier and is widely used in the food industry. when making cultured buttermilk with a lactic culture, the buttermilk also was fermented, hence the product we have today

Swiss cheese manufacture

Slow (overnight) fermentation, then brine-salted, pH 5.2 is critical, propionibacterium shermanii grow later

How are the composites of milk arranged in milk?

Some dissolved, some colloidal, dispersed, suspended, or emulsified.

What are the yogurt cultures?

Strep. thermophilus and lactobacillus delbrueckii subspecies bulgaricus

Thermophilic cheese cultures

Streptococcus thermophilus lactobacillus helveticus or lactobacillus subspecies. delbrueckii bulgaricus -used for high-cook, dry cheeses more commercially important due to increased popularity of these cheeses

Thermophilic dairy starter cultures

Streptococcus thermophilus: paired with lactobacillus helveticus (in cheese) or lactobacillus delbrueckii subspecies. bulgaricus (in yogurt)

Brie short list

Surface growth, penicillium camemberti, flavor from protein and fat metabolism (NH3) Consumer preferences vary (mind to strong flavor) pH 4.6-4.9 after fermentation, pH 7.0 at end of ripening

How to separate milk proteins

Use chymosin or ph 4.6-5.7 and whey proteins will be in solution (0.8 g protein/100 ml so 20% of total milk protein) and casein will precipitate (2.5 g protein/100 ml so 80% of total milk protein)

Beta casein fractions

Very hydrophobic, proline-rich

General composition of milk

Water - 87-88% Carbs - 4.9-5.0% Lipid - 3.5 - 4.0% Protein - 3.3% (Casein 2.5% and whey proteins 0.8%) mineral (ash) 0.7%

Edam, gouda short list

Whey dilution, pH around 5.4, leuconostoc or other citrate fermentors, buttery flavors, few small eyes are possible

What does s. thermophilus do for L. bulgaricus

acidifies the milk, produces co2 and reduces the eh, produces small amount of formate, other organic acids

Cheese coagulated by chymosin post-manufacturing steps (ripening) also important

adjunct organisms, temperature and humidity, and culture activity

Function of stabilizers in yogurt and cultured dairy products

bind water, reduce syneresis, increase viscosity, improve consistency, maintain gel structure, especially important in stirred products

calcium in whey

calcium lost in whey is lost forever! calcium lost in curd is retained.

Washed curd cheeses

colby, monterey jack, new york cheddar, dutch cheeses, brick/limburger/munster Dilutes out lactose, results in less acid formed during fermentation Hot water performs like cooking (enhances syneresis and decreases moisture content) Cold water has the opposite effect, as water is adsorbed and moisture content increases (although lactose dilution still occurs)

properties of kappa casein

contains carbs (a glycoprotein), peptide consists of 169 amino acids, peptide bond between residue 105 and 106 is sensitive to hydrolysis by chymosin, when hydrolyzed kappa casein is no longer intact and two products are formed. so stabilizing property is lost

2 ways amino acid is metabolized and the end product

deamination (NH3) goes to keto acid Decarboxylation (CO2) goes to amine

Yogurt texture and rheology - too firm or viscous

excessive stabilizers, choice of stabilizers, EPS from the culture

What determines the pH of the cheese?

fermentation of lactose

role of salt

flavor, enhance syneresis, inhibitory to spoilage and other microorganisms (i.e., preservation) Controls growth of desirable microorganisms controls enzyme activity contributes to rind formation the 'percent' salt is not the relevant value, rather the salt-in-moisture (s/M) is more relevant

What do lipids in cheese produce and contribute to

free fatty acids, ketones contributes to flavor

Exerting control during cheese manufacture

how to control acidification (pH) How to control moisture content (aw) how to control texture development how to control flavor development how to control redox potential (Eh) ACTIVITIES ARE INTERRELATED

The casein micelle

large, disorganized, spherically-shaped aggregates that consist of 'sub-micelles' (raspberry like) alpha and beta are located within the core of the micelle and kappa is at the exterior. kappa fraction stabilizes the micelle and blocks the negatively charge phosphate groups inside

What determines how much lactose is available?

moisture in curd

carb utilization and culture growth during swiss cheese fermentation

must be at pH 5.2 +/- 0.1 for proper eye development Too low inhibits P. shermanii Too higher promotes overgrowth of p shermanii FInal ph around 5.6

What do minerals in cheese produce and contribute to

no products, contributes to texture

fermented olives

olives

Mozzarella

pH 5.1-5.2 is critical for proper stretching fermentation is incomplete, residual sugars are important. thermophilic LAB functional properties are critical

ph and aw of milk

pH 6.6 - 6.8 aw - 0.999

What products are formed from the hydrolysis of kappa casein

para-kappa-casein and glycomacropeptide

Fermented cucumbers

pickles