Cheese Science and Technology

Comprehensive vocabulary flashcards covering the dairy chemistry, microbial cultures, coagulation mechanisms, curd processing operations, and ripening biochemistry of cheese production.

Syneresis

The expulsion or shrinkage-driven removal of liquid whey from the curd network, promoted by cutting, stirring, elevated cooking temperatures, and acid development.

Casein Micelle

A submicroscopic, colloidal protein aggregate in milk consisting of $\alpha_{s1}$-, $\alpha_{s2}$-, $\beta$-, and $\kappa$-caseins held together by hydrophobic interactions, ionic bonds, and colloidal calcium phosphate clusters.

$\kappa$-casein (Kappa-casein)

The specific surface-layer fraction of the casein micelle whose hydrophilic, negatively charged macropeptide 'hairs' provide steric and electrostatic repulsion, preventing micelles from spontaneously aggregating in milk.

Isoelectric Point of Casein

The specific pH level ($\text{pH} = 4.6$) at which the net electrical charge of casein micelles reaches zero, eliminating electrostatic repulsion and inducing acid precipitation of curds.

Acid Curd

Curd formed strictly by milk acidification to $\text{pH } 4.6\text{--}4.7$, characterized physically as gelatinous, fragile, non-elastic, and exhibiting poor syneresis.

Direct Acidification

The process of adding food-grade acids (such as citric, lactic, or acetic acid) directly into milk to induce curd coagulation without bacterial fermentation.

Chymosin

The primary aspartic proteinase naturally found in the stomach of suckling calves (and now produced via genetic engineering) that initiates enzymatic milk clotting by specifically hydrolyzing the peptide bond of $\kappa$-casein.

Rennet

A broad operational term designating any enzyme extract or preparation (animal, microbial, or recombinant) utilized to coagulate milk in cheesemaking.

Glucomacropeptide

The polar, hydrophilic, negatively charged acidic peptide fragment cleaved from $\kappa$-casein by chymosin during enzymatic coagulation and lost into the whey stream.

Enzymatic Curd

Curd formed via chymosin hydrolysis and calcium-mediated cross-linking, characterized by an elastic network that can be molded, becomes plastic as pH declines, and readily undergoes syneresis.

Acid and Heat Coagulation

A curd formation technique combining moderate acidification ($\text{pH } 6.0$) with high heating ($> 85^\circ\text{C}$) to denature and cross-link whey proteins with caseins (used for Ricotta, Paneer, and Mascarpone).

Case Hardening

A processing defect resulting from excessively rapid cooking of curds, which creates an impermeable outer protein skin that impedes whey expulsion and entraps unwanted moisture.

60-Day Aging Rule

A United States federal regulation requiring raw milk cheeses to be aged at least $60\text{ days}$ at $35^\circ\text{C}$ or higher prior to commercial distribution to allow natural pathogen die-off.

Thermalization

A sub-pasteurization heat treatment applied to raw cheese milk to lower bacterial counts while conserving indigenous milk enzymes; milk treated this way is legally designated as raw.

HTST Pasteurization

High-Temperature Short-Time continuous pasteurization standard consisting of heating milk to $72^\circ\text{C}$ for $15\text{ seconds}$.

LTLT Pasteurization

Low-Temperature Long-Time batch/vat pasteurization consisting of heating milk to $63^\circ\text{C}$ for $30\text{ minutes}$.

Bactofugation

A specialized centrifugal separation step applied to cheese milk that removes bacterial vegetative cells and endospores by density without heat-damaging native enzymes.

Lactoperoxidase System

An endogenous antimicrobial defense mechanism in milk wherein lactoperoxidase utilizes hydrogen peroxide to oxidize thiocyanate into hypothiocyanate, which can inhibit lactic starter cultures.

Mesophilic Starter Cultures

Lactic acid bacteria with an optimal growth range between $10^\circ\text{C}$ and $40^\circ\text{C}$ (such as Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris), used in Cheddar, Gouda, and soft cheese manufacture.

Thermophilic Starter Cultures

Heat-tolerant lactic acid bacteria with growth optima between $42^\circ\text{C}$ and $45^\circ\text{C}$ (such as Streptococcus thermophilus and Lactobacillus helveticus), used in cheeses cooked at high temperatures like Swiss, Parmesan, and Mozzarella.

Propionic Acid Fermentation

The biochemical reaction performed by Propionibacterium in Swiss-type cheeses converting lactic acid into propionic acid, acetic acid, carbon dioxide, and water: $3\text{ lactate} \rightarrow 2\text{ propionate} + \text{acetate} + \text{CO}_2 + \text{H}_2\text{O}$.

Eye Nucleation Sites

Microscopic weak spots, mineral particles, or voids inside the curd matrix of Swiss-type cheeses where accumulating carbon dioxide gas collects and expands into smooth, round eyes.

2-Heptanone

A prominent volatile methyl ketone generated via lipase-mediated fatty acid hydrolysis and oxidation in blue cheeses, responsible for the classic piquant 'blue' aroma.

Penicillium roqueforti

A microaerophilic, carbon-dioxide-sensitive internal mold species inoculated into cheeses like Roquefort, Gorgonzola, and Stilton to develop internal blue veins through intense lipolysis and proteolysis.

Needling

The mechanical piercing of stainless-steel needles through blue cheese wheels to provide gas channels that vent inhibitory carbon dioxide and introduce oxygen required for mold sporulation.

Penicillium camemberti

The white surface mold inoculated onto soft bloomy-rind cheeses (such as Brie and Camembert) that consumes lactate and digests proteins, yielding alkaline products that neutralize surface acidity.

Surface-to-Center pH Gradient

The progressive neutralization in surface-ripened soft cheeses (Brie/Camembert) driven by mold consumption of lactate and inward diffusion of ammonia, creating an alkaline, gooey perimeter around an acidic, chalky core.

Smear Ripening

A surface-curing method wherein the rind is periodically washed or rubbed with a microbial brine transfer to promote the growth of salt-tolerant bacteria and yeasts (such as Brevibacterium linens).

Brevibacterium linens

An obligately aerobic, salt-tolerant ($\le 15\%\text{ NaCl}$) bacterium that forms orange-red surface colonies on washed-rind cheeses and generates pungent sulfur, amine, and ammonia aromas via proteolysis and deamination.

Geotrichum candidum

A yeast exhibiting mold-like growth commonly found on traditional rinds, recognized for generating a distinctively folded, wrinkled, or 'brainy' rind texture.

Salt-in-Moisture (S/M) Ratio

A primary analytical predictor of cheese ripening potential expressing the percentage of salt dissolved exclusively within the water phase ($\text{S/M} = \frac{\%\text{ Salt}}{\%\text{ Moisture}} \times 100$).

Moisture in the Non-Fat Substance (MNFS)

A compositional index reflecting the degree of protein matrix hydration, calculated as the moisture fraction relative to total non-fat solids, which controls the velocity of enzymatic proteolysis during aging.

Pasta Filata

A cheese-making style (exemplified by Mozzarella and Provolone) wherein acidified curds are immersed in hot water or whey and mechanically stretched, kneaded, and shaped into smooth strands.