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What do you call cheese that doesn’t belong to you? “Nacho Cheese” Download slides: http://acswebinars.org/tunick
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Upcoming ACS Webinars™
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Thursday, June 2, 2011
Can We Grow Energy? The Role of Chemistry in the Energy Future
The early bird may get the worm, but the second mouse gets the cheese.
Bruce Dale, Michigan State University
Thursday, June 9, 2011
Wow Your Crowd: Presenting Online with Power Jeff Hiller, JB Training Solutions
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12/31/2014
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12/31/2014
ACS WEBINARS™ May 26, 2011
The Chemistry of Cheese and Why We Love It
The Chemistry of Cheese and Why We Love It
Michael H. Tunick
Dairy & Functional Foods Research Unit Wyndmoor, PA Michael Tunick, USDA
Bill Courtney, Cheese-ology Macaroni & Cheese
Please submit questions via the Questions Panel in GoToWebinar Agricultural Research Service
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Cheese Chemistry Americans consume 14 kg of cheese per capita without realizing the extent to which chemistry is responsible for the production of this food
Division of Agricultural and Food Chemistry
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Topics
Cheese Chemistry Species and diet of animal producing the milk Processing conditions Storage conditions
Sources of milk Cheesemaking Breakdown of milk components Flavor compounds and cheese varieties
Affect structural development and breakdown of Protein Carbohydrates Lipids 17
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Bovine Milking Breeds Holsteins represent 90% of US dairy herd Produce more milk than other breeds Jerseys make up 7% Produce more fat and protein
Holstein 10900 kg milk/yr 3.7% fat/3.0% protein
Ayrshire 7117 kg 3.9% f/3.2% p
Jersey 7636 kg 4.8% f/3.6% p
Brown Swiss 8528 kg 4.1% f/3.4% p
Guernsey 7318 kg 4.6% f/3.3% p
Milking Shorthorn 7286 kg 4.0% f/3.1% p
Wendorff and Paulus, Dairy Pipeline 23(1), 1-7 (2011) 19
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Pasture Compounds
Other Species Provide Milk
Animals fed on pasture plants have additional compounds in their milk Terpenes include linalool (floral), α-pinene (pine) Unsaturated fatty acids break down to form 2,4decadienal (mayonnaise, bread), nonanal (green), others Carotenoids lead to citronellol and geranyl acetate (rose), others 21
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Milk from Goats and Sheep
Cheesemaking Pasteurize and Standardize Milk Add Starter Bacteria Add Rennet Cut and Cook Curd Drain Whey Pile Curds Mill or Stretch Curds Add Salt Press Coat or Package Ripen
Contains more short-chain fatty acids, resulting in smaller, more volatile odorant molecules Fatty acid Butyric, 4:0 Caproic, 6:0 Caprylic, 8:0 Capric, 10:0 Lauric, 12:0
Cow 3.8 2.4 1.4 3.5 4.6
Goat 2.2 2.4 2.7 10.0 5.0
Sheep 3.5 2.9 2.6 7.8 4.4
Jensen et al., J. Dairy Sci. 74, 3228-3243 (1991) Park et al., Small Ruminant Res. 68, 88-113 (2007) 23
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Compound and Texture Formation Enzymes from starter culture microorganisms and coagulant degrade Protein (primarily casein) Carbohydrates (lactose and citrate) Lipids
Starter Culture Types of starter and coagulant responsible for development of different flavors Usually a combination of Streptococci and Lactobacilli species Lactose lactic acid pH reduced Citric acid metabolized Some proteolysis
Resulting in Flavor compounds Texture formation 25
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Nonstarter Lactic Acid Bacteria
Coagulant
Starter bacteria decline from 109 to 107 cfu/mL within first month Adventitious NSLAB proliferate during ripening From airborne microflora, resistance to heat and disinfection Include Lactobacillus casei, Lb. plantarum, Lb. curvatus, many others Contribute to flavor through proteolysis, lipolysis 27
Usually rennet, which includes chymosin, pepsin, and lipase Formerly from calf stomach, now from microbial sources such as Rhizomucor miehei and Cryphonectria parasitica Chymosin cleaves κ-casein at Phe105-Met106 Casein micelle falls apart Casein coagulates, forming curds αs1- and β-casein hydrolyzed 28
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Proteolysis plasmin + coagulant
casein
peptides microbial enzymes + coagulant decarboxylation
amines deamination
aldehydes
degradation
amino acids
sulfur compounds
oxidative deamination
α-ketoacids + ammonia
carboxylic acids + alcohols methyl thioesters 29
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Cow
Cheese Microstructure Cheddar Mozzarella
Goat
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12 wk
Carbohydrate Catabolism
Cheddar Microstructure During Aging
Galactose
Lactose
24 wk
36 wk
Glucose
Ethanal Ethanol Ethanoic acid
Citrate O-
Pyruvate
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2,3-Butanedione (diacetyl), 2,3-Butanediol, 3-Hydroxy-2-butanone (acetoin)
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Lipolysis
Average Composition Cheese Type
triglyceride
Water
Protein
Fat
Vitamins & Minerals
Soft
520
200
Semi-hard
220
60
400
250
270
80
Hard
350
270
310
70*
Very hard
300
290
330
80
g/kg
lipase
fatty acids
βketoacids
methyl ketones
2º alcohols
4- or 5hydroxyacids
γ- or δ-lactones
unsaturated fatty acids
aldehydes
free fatty acids
*50 g hard cheese contains 40% of RDA of Ca, 15% of vitamin A, 10% of vitamin B2, 20% of vitamin B6, and 40% of vitamin B12
esters
acids + alcohols
Walther et al., Dairy Sci. Technol. 88, 389-405 (2008) 35
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Classes of Flavor Compounds • • • • • • • •
Most Common Compounds
Alcohols Aldehydes Amino acids Esters Fatty acids Ketones Lactones Other compounds
Compound
Cheddar
Butyric acid
1
Propionic acid
4
Isovaleric acid
6
Ethyl butyrate
2
Emmental
Camembert 1
1 2 7
Ethyl caproate
5
Diacetyl
13
5
5
3-Methyl butanal
3
6
3 4
Methional
8
2
Furaneol/ homofuraneol
14
3, 4
Yvon and Rijnen, Int. Dairy J. 11, 185-201 (2001) 37
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Phenylalanine
Categories of Ripened Cheese • • • • • • • •
Degradation leads to phenylacetaldehyde, phenethylacetate, phenylacetic acid, 2phenylethanol, phenylethanal Responsible for floral rose-like notes of Camembert Responsible for unclean off-flavors in Cheddar Phenylacetaldehyde responsible for honey-like notes in Gruyère 39
Very hard (Parmesan, Romano) Hard (Cheddar, Colby) With eyes (Emmental, Gruyère) Pasta filata (Mozzarella, Provolone) Interior mold (Roquefort, Stilton) Surface mold (Brie, Camembert) Smear ripened (Limburger, Brick) Brined (Feta, Domiati) 40
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Cheddar and Colby
Cheddar Compounds at 9 Months
Starter: Streptococcus thermophilus and Lactobacillus bulgaricus Cooking: 38-39°C Whey removal: Cheddar stacked, Colby washed Storage: 2-10°C for 2-12 mo
Fatty acids (670-3200 mg/kg): Acetic (vinegar), butyric (cheesy), caproic (sweaty), caprylic (burnt waxy) Diacetyl (740 μg/kg, buttery) Methional (200 μg/kg, boiled potato) Dimethyl trisulfide (7 μg/kg, garlic) Drake et al., J. Dairy Sci. 93, 5069-5081 (2010) 41
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Lactones
Parmesan
From lipolysis Peach/Coconut Flavors
γ-Octalactone 8 μg/kg
δ-Decalactone 34 μg/kg
Starter: Previous day’s whey Cooking: Up to 55°C Storage: 2-10°C for 14 mo to 4 yr δ-Dodecalactone 3 μg/kg
Drake et al., J. Dairy Sci. 93, 5069-5081 (2010)
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Mostly ethyl esters from C2 to C16 Methyl, propyl, and butyl esters also found Free amino acids 44
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Amino Acids
Cheeses with Eyes
• Bitter Arginine, isoleucine, leucine, methionine, phenylalanine, tryptophan, tyrosine, valine • Sweet and bitter Lysine, proline
Swiss/Emmental Gruyère Cooking: Up to 54°C Storage: 20°C for 4-12 mo Propionibacterium freudenreichii added after lactose fermentation Lactate converted into ethanoate, propanoate, and CO2, which collects and forms eyes
• Sweet Alanine, glycine, serine, threonine • Sour Aspartic acid, histidine • Umami Glutamate McSweeney and Sousa, Lait 80, 293-324 (2000) 45
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Furans
Maillard Reactions C=O +
Furaneol
from lactose, glucose, or galactose
Homofuraneol lysine
Caramel flavors in Emmental Industrial flavoring agents Found in wine
many products 47
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Maillard Reactions _
Sulfur-Containing Compounds Methionine
CO2 2-aminoethanethiol Methionine-γ-lyase
cysteine
2-thiazoline
Methional (boiled potato)
R
Example: 2-acetylthiazoline (popcorn)
CH3SH
Dimethyldisulfide
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Methanethiol
Dimethyltrisulfide (garlic, sulfury) 50
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Pasta Filata Cheeses
Alcohols
Mozzarella, Provolone Traditional Mozzarella made from water buffalo milk Curd stretched instead of pressed Mozzarella is meltable with mild flavor Provolone is aged > 4 mo
1-Octen-3-ol From linoleic and linolenic acids Most common alcohol in cheese Flavor enhanced by 1-octen-3-one 2-Methylbutanol, 3-methylbutanol, 3-methyl-2buten-1-ol also found in water buffalo Mozzarella 51
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Cheeses Ripened by Interior Mold
Roquefort
Methyl Ketones P. Roqueforti converts fatty acids to β-ketoacids Decarboxylation produces methyl ketones with blue cheese odor 2-Pentanone, 2-heptanone, 2-nonanone, and 2undecanone common in blue cheese varieties Enzymatic reduction yields secondary alcohols 2-Heptanol (herbaceous) is key odorant of Gorgonzola
Stilton
Blue-green Penicillium roqueforti powder added to milk or curd Skewered during ripening to introduce oxygen Storage: 5-10°C at 90% humidity for 3-6 mo
Gkatzionis et al., Food Chem. 113, 506-512 (2009) 53
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Cheeses Ripened by Surface Mold
Brie 0.5-3 kg wheels
Esters Produced by reaction of free fatty acid and alcohol Ethyl esters are dominant since ethanol is most common alcohol available Ethyl butanoate and ethyl hexanoate found in many cheeses and impart fruity flavors Branched esters include ethyl isobutanoate (unripe fruit) and ethyl-3-methylbutanoate (fresh cheese)
Camembert 250 g disks
Curd ladled and not broken Surface coated with Penicillium camemberti mold Lactic acid removal increases pH to 7 CaPO4 becomes insoluble and migrates to surface, weakening protein matrix Ripens from outside over 2-4 wk 55
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Camembert Compound Diacetyl δ-Decalactone
Odor Buttery
Smear-Ripened Cheeses
Concentration Odor threshold (μg/kg ) (μg/kg ) 90 10 995
400
3-Methylbutanal Malty
120
13
1-Octen-3-ol
Mushroom
100
35
Sulfurous, garlic-like
75 265 330
Methional Methanethiol Dimethyl sulfide
Limburger
Pont-l’Évêque
Brevibacterium linens (reddish bacterium) brushed on surface after it is first colonized by yeasts Butanoic, 3-methylbutanoic, caproic acids produced
0.2 0.06 1.2
Kubícková and Grosch, Int. Dairy J. 8, 17-23 (1998) 57
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Fatty Acids Variety Mozzarella
Concentration (mg/kg ) 360
Limburger
4200
Swiss
4300
Camembert
5070
Cheddar Parmesan Roquefort
Feta Milk: Sheep, with up to 30% goat Cooking: 34-36°C for 45-60 min Storage: In barrels containing brine (7% NaCl), at 0-4°C for at least 2 mo
9500 13700 26000
McSweeney, Int. J. Dairy Technol. 57, 127-144 (2004) 59
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Aldehydes
-2H
H2O
+ NH3 + CO2
Many produced from Strecker degradation Amino acid
Strecker aldehyde
Odor threshold (ppb)
Isoleucine
2-Methylbutanal
2
Cocoa, fruity
Leucine
3-Methylbutanal
3
Fruity, peach, cocoa
Valine
2-Methylproponal
2
Pungent, fruity
Methionine
Methional
0.2
Cooked potato
Phenylalanine
Phenylacetaldehyde
4
The characteristics of cheese depend on the chemistry involved in the way it is made and stored, and knowledge of this chemistry leads to the creation of a better product
Flavor
Honey, sweet, flowery
Weenen and van der Ven, in “Aroma Active Compounds in Food,” ACS Symposium Series 794, 183-195 (2001) 61
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Q&A SESSION The Chemistry of Cheese and Why We Love It
Michael Tunick, USDA
Bill Courtney, Cheese-ology Macaroni & Cheese
Please submit questions via the Questions Panel in GoToWebinar
Download slides: http://acswebinars.org/tunick 63
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Can We Grow Energy? The Role of Chemistry in the Energy Future Bruce Dale, Michigan State University
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www.twitter.com/acswebinars
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