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*Over 200 delicious recipes for beef, pork,
lamb, game, chicken, turkey, duck, fish,
shellfish, vegetables, fruits, legumes, ice
cream bases, sauces, and yogurt.
*The basics of sous vide cooking with “learn
by doing” sections.
*10-page table with times and temperatures
for every cut of meat or type of vegetable.
Find Sous Vide for the Home Cook on Amazon.com today!
Sous Vide Cooking and Chemistry
Download the presentation and slides ONE WEEK after webinar:
http://acswebinars.org/sous-vide
ACS WEBINARS™ May 9, 2013
8
Dr. Sara Risch
Popz Europe
Dr. Douglas Baldwin
Author
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Sous vide cooking and chemistry
Douglas E. Baldwin
Department of Applied MathematicsUniversity of Colorado at Boulder
ACS Webinar — May 9, 2013
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How often do you cook?
(a) Cook almost everyday.
(b) Not daily, but quite a lot.
(c) Only for special occasions.
(d) Almost never.
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sous vide /su: ’vi:d/ adjectival & adverbial phr.L20. [ French, from sous under+ vide vacuum.]Of food: (prepared) by cooking invacuumized pouches at preciselycontrolled temperatures.
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Optimal food temperatures▶ Beef, lamb, and pork
∼50 °C Rare∼55 °C Medium-rare∼60 °C Medium>70 °C Well done
▶ Fish and shellfish∼49 °C Medium-rare
▶ Baked goods∼90 °C Breads, rolls, muffins, etc.
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Common kitchen heat sources
∼70 °C Slow-cooker
100 °C Boiling water
125–200 °C Oven
150–250 °C Skillet
200–350 °C Grill
1500–2000 °C Blowtorch
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Sous vide cooking:▶ Cook at the food’s optimal temperature.▶ If 55 °C is medium-rare,
then use a 55 °C water-bath⇒meat can’t exceed 55 °C⇒ nothing overcooked⇒medium-rare from edge to edge
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Vacuum-sealing benefits
▶ Removing air improves heat transfer▶ Increases shelf-life
• Food can’t be recontaminated• Inhibits off-flavors from oxidation• Reduces aerobic bacterial growth
▶ Improves nutrition and flavor• Stops flavor volatile evaporation• Stops nutrients leaching into water
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Outline
▶ Soft-cooked eggs• Protein denaturation
▶ Beef chuck roast• How heating changes meat• Extended heating tenderizes
▶ Chicken breasts• Pasteurizing for safety
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Protein denaturation
Heat
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Protein denaturation
▶ Heat — cooking, baking, …▶ Mechanical agitation — whipping▶ pH change — vinegar, lemon juice, …▶ Inorganic salts — curing and brining▶ Organic compounds — alcohol marinades▶ Detergents — cleanup
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Yolk temperatures in 75 °C water
5 10 15 20 25 30Time HminL
10
20
30
40
50
60
70
Temp H°CL
Measured yolk temperatures of 14 “large” eggs.
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Reaction rate
▶ Temperature• Arrhenius reactions:
10 °C increase roughly doubles rate• Yolk denaturation:
1 °C increase roughly doubles rate▶ Catalysts
• Enzymes catalyze biochemical reactions▶ Concentration
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When you grill meat or poultry, do you
(a) always use a thermometer to see when it’sdone,
(b) sometimes use a thermometer, or
(c) never use a thermometer?
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Meat proteinsMeat’s about 75% water, 20% protein,
and 5% fat and other substances.Proteins:
▶ Muscle fibers— mostly myosin & actin
▶ Soluble proteins— mostly enzymes and myoglobin
▶ Connective tissue— mostly collagen, less elastin
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Meat protein denaturing
In traditional cooking when heating:▶ Muscle fibers shrink
starting 35–40 °C up to ∼80 °C▶ Soluble proteins aggregate and gel
starting ∼40 °C and finishing ∼60 °C▶ Connective tissues shrink
starting ∼60 andmore intensely above ∼65 °C
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Doneness
50 °C Rare — muscle fibers andsoluble proteins start denaturing
55 °C Medium-rare — more muscle fibers andsoluble proteins denature
60 °C Medium— most soluble proteins denatured
>70 °C Well done— connective tissue start denaturing— muscle fibers squeeze out water
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If you eat beef, do you prefer it
(a) rare,
(b) medium-rare,
(c) medium, or
(d) well done?
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If 55 °C is medium-rare,why not cook at 55°C?
You can with sous vide cooking.
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Slower reactions tenderize
Holding meat at 55–60 °C for hoursto days increases tenderness because
▶ Enzymes can catalyzeconnective-tissue protein hydrolysis
▶ Collagen slowly starts to denaturearound 51 to 53 °C
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Beef chuck roast
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Meat flavor
1. Browning or Maillard reaction• Roast and savory flavors• Starts noticably ∼130 °C• Good browning starts ∼150 °C
2. Fat makes• lamb taste like lamb and• beef taste like beef.
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Maillard reaction
▶ Complex reaction betweenamino acids and reducing sugars
▶ Produces hundreds of reaction by-products▶ Reaction rate increased by
• Increasing temperature• Adding a reducing sugar• Increasing the pH
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Rapid browning methods
▶ Beef and lamb• Butane blowtorch• Very hot grill or broiler
▶ Chicken and pork• Pan with smoking-hot oil• Shimmering oil with 4% glucose wash• Very hot grill or broiler
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Beef chuck roast
1. Preheat water to 55 °C for medium-rare
2. () Pre-sear with blowtorch or grill
3. Vacuum-seal roast in a large pouch
4. Put into water bath for 1–2 days
5. Remove from pouch and pat dry
6. Sear each side to a mahogany brown
7. Season and serve immediately
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When do you stop cooking a chicken breasts?
(a) When it’s juices run clear.
(b) When it’s white when you cut into it.
(c) When it reaches 75 °C/165 °F.
(d) When it’s dry and stringy.
(e) Some other criteria.
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Food microorganisms
..Spoilage.
Beneficial
.
Pathogenic
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Many ways to reduce pathogens
▶ Heat — both time and temp important▶ Inorganic salts — curing▶ pH changes — acidifying▶ Herbs and spices — essential oils▶ Mechanical agitation — very high pressures▶ Alcohol — marinades▶ Ionizing radiation — not for home kitchens
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“Danger Zone”?
▶ Traditional “danger zone” is 5 to 60 °C▶ Food pathogens don’t grow below−1.3 °C▶ Food pathogens don’t grow above 52.3 °C▶ Dangerous growth takes days at 5 °C▶ Pasteurization takes 43 min at 60 °C
but 3 hr 20 min at 55 °C
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Pasteurization reduces risk
▶ Reduce but can’t eliminate pathogens▶ Healthy may need 105 to 109 to get sick▶ Immunocompromised 1–10/g to get sick▶ 15–20% of US immunocompromised▶ 106 → 1 reduction usually recommended
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Pathogens of interest
▶ Salmonella species▶ Pathogenic strains of Escherichia coli▶ Listeria monocytogenes— the toughest
▶ 106 → 1 after 2 min at 70 °C▶ 106 → 1 after 20 min at 62.5 °C▶ 106 → 1 after 200 min at 55 °C
▶ Spore forms, like the Clostridium species
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Sous vide chicken breasts
1. Preheat water bath to 60 °C.
2. Individually vacuum-seal the breasts.
3. Put sealed pouches in water bath.
4. Cook them for at least 2 hours.
5. Remove from bath and pouches. Pat dry.
6. Sear in a skillet with smoking-hot oil.
7. Serve immediately.
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Balance time and temperature
..Temperature
.Time
.
Safety
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Doneness
.
Texture
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Pork chops
▶ Medium-rare to medium⇒ 55–60 °C▶ Moderately tender⇒ short to moderate cooking times▶ 60 °C & 20 mm thick⇒ 1½ hours to pasteurize
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Filet mignon
▶ Rare to medium-rare⇒ 50–55 °C▶ Prized tenderness⇒ short cooking time▶ 50–55 °C & short time⇒ can’t pasteurize⇒ healthy people only▶ 50 °C⇒ pathogen growth⇒minimize time▶ 55 °C⇒ short time or mushy texture
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Additional Resources
▶ www.DouglasBaldwin.com▶ Free sous vide cooking guide▶ YouTube video demos▶ Review article [IJGFS vol. 1 (2012) pp. 15–30]
▶ D.B.’s Sous Vide for the Home Cook (2010)▶ Over 200 recipes▶ Less technical than website or review article
▶ Other food science books:▶ H. McGee’s On Food and Cooking (2004)▶ N. Myhrvold et al.’sModernist Cuisine (2011)
And now your chance to win!
1
“How do you use your chemistry
skills & knowledge to enhance
your kitchen creations?”
Facebook.com/acswebinars
or
Sous Vide Cooking and Chemistry
Download the presentation and slides ONE WEEK after webinar:
http://acswebinars.org/sous-vide
ACS WEBINARS™ May 9, 2013
2
Dr. Sara Risch
Popz Europe
Dr. Douglas Baldwin
Author
Stay Connected…
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Upcoming ACS Webinars™ www.acswebinars.org
Thursday, May 16, 2013
2013 Chemical Entrepreneurship Series
Business Model Analysis:
How will your company make money?
Ms. Barbara Bry, COO of Blackbird Ventures
Mr. Neil Senturia, CEO of Blackbird Ventures
Thursday, May 23, 2013
The Transition from Graduation
to a Career in Industry
Ms. Anne DeMasi, Hazard Communications Manager, Chemtura
Dr. Michael Abrams, Principal Scientist, Arkema
Ms. Dawn Mason, HR Manager, Eastman Chemical Company
Contact ACS Webinars™ at [email protected] 4
If you enjoyed this ACS Webinar today…
please support the program!
5
Find the many benefits of ACS membership!
www.join.acs.org
And now your chance to win!
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“How do you use your chemistry
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your kitchen creations?”
Facebook.com/acswebinars
or
ACS Webinars™ does not endorse any
products or services. The views expressed in
this presentation are those of the presenter
and do not necessarily reflect the views or
policies of the American Chemical Society.
7 Contact ACS Webinars™at [email protected]
Upcoming ACS Webinars™ www.acswebinars.org
Thursday, May 16, 2013
2013 Chemical Entrepreneurship Series
Business Model Analysis:
How will your company make money?
Ms. Barbara Bry, COO of Blackbird Ventures
Mr. Neil Senturia, CEO of Blackbird Ventures
Thursday, May 23, 2013
The Transition from Graduation
to a Career in Industry
Ms. Anne DeMasi, Hazard Communications Manager, Chemtura
Dr. Michael Abrams, Principal Scientist, Arkema
Ms. Dawn Mason, HR Manager, Eastman Chemical Company
Contact ACS Webinars™ at [email protected] 8