Biochemistry in the Kitchen
Edition: 1
Copyright: 2023
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Biochemistry in the Kitchen is designed for an introductory one-semester course for nonscience students who need to fulfill a requirement for a “lab-science course.” The intent is to provide these students with a robust understanding of biochemical phenomena illustrated in the context of cooking and other practical everyday experiences in the world around them. The book is “self-contained,” assuming only minimal previous exposure to science courses in middle school or junior high school. Questions are posed such as “What happens during cooking?,” “Why does that happen?,” and “How does that work?” Scientific concepts necessary to understand the observed phenomena are presented, and answer these questions in a sequential order, starting with “first principles” in the early chapters and adding new information that builds on the initial concepts to explain more complicated phenomenon. Scientific jargon is avoided wherever possible, instead using “common terms” to explain what is happening. The book is accompanied by online “Laboratory Experiments” that can be conducted in the students’ home, kitchen, or classroom. As such, this course is appropriate for use at the introductory college level or high school level.
Students who successfully complete Biochemistry in the Kitchen will be able to:
- Demonstrate a fundamental understanding of the principle concepts of biochemistry and be able to communicate scientific ideas effectively using common everyday terms and experiences to illustrate concepts.
- Understand the scientific method and be able to apply scientific reasoning to investigate questions, solve problems, and form conclusions.
- Be able to understand the fundamental role that water plays in biochemical processes, with particular application to food chemistry and cooking practices.
- Evaluate scientific data, develop hypotheses, interpret results, and apply this information to applications involving cooking, emulsifications, acid/base buffering action, hydration of polymers, denaturation of proteins, catalysis by enzymes, human metabolism, fermentation, food safety, and bacterial growth.
- Display an understanding of food ingredients and their purpose.
- Communicate what chemical transformations occur during cooking, explain why humans cook food, and how humans obtain energy from eating foods.
Organization
There are eleven broad topics addressed in this book, organized into four modules.
Biochemistry cannot be understood without understanding the properties of water. Accordingly, the four chapters which constitute the first module explain the peculiarities of water and how we experience these properties of water in our everyday lives, explaining phenomena such as the following:
- Why cooking with steam is more effective than cooking with boiling water?
- Why cooling a hot beverage with ice is more effective than using cold water?
- What is wind chill?
- Why do oil and water separate into distinct layers?
- What are saturated fats, unsaturated fats, and omega 3 fats?
- How does soap work?
- How is mayonnaise made?
- Why is phosphoric acid or citric acid added to so many foods?
- Why do we breathe fast when we exercise?
The four chapters comprising the second module describe biological polymers, specifically, polysaccharides and proteins. The behavior of these polymers in water explains the structures these polymers form and what happens to these polymers when we prepare the foods that we eat. For examples, topics addressed in the second module include the following:
- Why is sugar sweet but starch made out of sugar units is not?
- Why are some kinds of sugars sweeter than others?
- What happens to starch while making gravy?
- Why do noodles take on water when heated?
- Why does clear liquid “egg white” turn into a solid white gel when heated?
- Why is vinegar added to water when making poached eggs?
- How do you make meringue out of egg whites without cooking?
- How do you make yogurt, cheese, and butter out of milk?
- Why do meats become tender when you boil them in water?
- Why do foods turn brown when you cook them?
- What do meat tenderizers and meat marinades do?
The third module describes what happens to biological polymers when we eat them, and how humans capture energy from the food nutrients that we eat. These chapters address the following:
- What is the difference between digestion and metabolism?
- Why do foods high in fats have a higher calorie content than do foods made primarily of starches or proteins?
- How do we get energy out of these foods?
- How does the Keto diet work?
- Why do we need oxygen to live?
- How is beer, wine, and vinegar made?
- Why is wheat “gluten” in so many foods?
- Why does bread rise when leavened?
- Why do cookies rise when baked in the oven?
The last module includes a chapter on food safety, bacterial growth, why foods spoil, and why some bacteria cause food-borne illnesses. There is a chapter discussing the various techniques humans have developed over the centuries to preserve foods and how those processes work to suppress microbial processes. The final chapter introduces the concept of the human microbiome—the bacteria that live in partnership with humans that are essential to keep us healthy. Some of the questions addressed in this fourth module include the following:
- Why do we chill foods to prevent spoilage?
- Food recalls: Where do food-borne illnesses come from?
- Why can some foods be stored at room temperature?
- Why are bags of corn chips or potato chips sold “half-empty”?
- What are probiotic bacteria? What is a prebiotic food?
When I was a university provost, I often heard complaints from students and their deans that the science courses intended for nonscience majors were “boring,” “over their heads,” “tedious,” or “irrelevant to their lives.” They wanted something “different,” something that would be useful to everyday life. When I returned to a faculty role, I committed myself to the endeavor of developing a “real science” course that would be meaningful to most people and present information to students in such a way that it would be readily understandable and applicable such that they would remember the basis of these biochemical phenomena throughout their lives. The most rewarding feedback that I have received from students are vignettes they tell me months or years later describing how they recalled at work why they used lemon juice in making guacamole or on vacation why lemon juice removes fish odor off their hands. I hope you have the same delightful experience with this book!
Preface
Purpose & Intent
Chapter 1 – A Recipe for Making Jello - Hypothesis Testing & The Scientific Method
Real Science is not just “Memorizing Facts”
Establishing Scientific “Facts”
- Making Sense of Observations
- Drawing on Past Experience
- Possible Explanations – Hypotheses
- Identifying Variables
- Hypothesis Testing
- Hypothesis Refinement
- Reproducibility – “Accepted Fact”
Companion: Lab Exercise 1 - Making Jello - Hypothesis Testing (The Scientific Method)
Chapter 2 - What’s So Special About Water ? – The Power of Hydrogen Bonding
- Liquid Water, Gaseous Steam, Solid Ice
- Atoms, Molecules & Hydrogen Bonding
- Types of Chemical Bonding:
Ionic – Theft & Abandonment
Covalent - Sharing
Polar Covalent – Some Atoms Share More Equally Than Others
- Boiling Water & Making Tea – Cooking & Cooling Energy in Hydrogen Bonds
Latent Heat of Phase Changes – Energy Needed to Break Hydrogen Bonds
- Why Blow on Hot Soup to Cool It?
Wind Chill
- Why Do Popcorn Kernels “Pop” When Heated?
- Making Tea - Plain or With Sugar & Lemon?
Substance that are Soluble in Water Form Hydrogen Bonds
Types of Polar Molecules
Ions are Hydrated by Layer of Water Molecules
Companion: Lab Exercise 2 - Tea, Eggs & Popcorn - Steam, Water & Ice (Hydrogen Bonding, Latent Energies of Vaporization & Freezing, Solubility)
Chapter 3 - Oil & Water Don’t Mix – Behavior of Nonpolar Molecules - “Hydrophobicity”
Nonpolar Molecules
- Hydrophobicity
- Why Does Italian Dressing (Oil, Water & Vinegar) Separate into Two Layers
Understanding Entropy by Playing Dice
- Why Does the Separation Occur Faster at Hot Temperature and Slower at Cold Temperature?"
Temperature Multiples the Effect of Entropy
- Demystifying Food Labels - What are Saturated, Unsaturated, Cis, Trans & Omega Fats?
Types of Types of Hydrophobic Molecules in Nature (non-living things) - Hydrocarbons
Types of Nonpolar Hydrophobic Molecules in Living Organisms – Triglycerides: Fats & Oils
Liquid or Solid? Effect of Chain Length, Double Bonds & Cholesterol
- Comparing Food Labels & Melting Temperature
% Saturated, % Unsaturated, % Polyunsaturated & Presence of Cholesterol
- What’s the Difference Between Butter and Margarine?
Partial Hydrogenation & Trans Fats
- The Perils of Advertising – Some Naturally-Occurring Trans Fats Are Good For You
- What’s All This Chatter about Omega 3’s and Omega 6’s – What are they?
Getting Oil & Water to Emulsify
- How Soap Works
Free Fatty Acids are Amphipathic Molecules
Blowing Bubbles
Washing Greasy Dinner Dishes – Making Micelles – Emulsification
- How is Soap Made?
- Why are Mono- and Di-glycerides in my Ice Cream?
- Making Mayonnaise – Emulsifiers in Egg Yolk
- Summary – Types of Lipids
- Why is there so much Lecithin in Egg Yolk?
Phospholipid Bilayers and Cell Membranes
- LDL and HDL - An Important Role for Phospholipid Micelles in Human Blood
Companion: Lab Exercise 3 - Italian Dressing, Probability, Soap & Mayonnaise (Hydrophobicity, Entropy & Emulsifiers)
Chapter 4 - Buffering Against Change – pH, acids, bases, and buffering agents
- The 2nd Special Property of Water – transient ionization
- Do You Have A Mole?
Comparing Equal Numbers of Things With Different Weights
- pH, Acids & Bases
Measuring H+ concentration
Measuring –OH concentration
- pH of Various Foods and Household Substances
- Vinegar & Ammonia – transient ionization of weak acids and bases
Carboxylic Acids
Amine Groups
- Why Use Lemon With Lobster or Fish?
Tipping the Balance with pH
- The “Balance Point” Between the Charged Ionic Form and the Uncharged Molecular Form
- Acetate, Citrate, Phosphate & Bicarbonate - Why are these Chemicals in in My Food
Buffers Resist Change in pH
- Why Do You Breathe Rapidly During Exercise?
Sodium Bicarbonate
Companion: Lab Exercise 4 - pH of Foods - Vinegar, Ammonia & Baking Soda (Acids, Bases, pH, and Buffering Capacity)
Chapter 5 - Carb Up! - Why Sugar is Sweet but Starch is Not – Carbohydrates
- Human Blood Glucose Levels
- Types of Carbohydrates
Monomers - Monosaccharides
Dimers - Disaccharides
Polysaccharides; Starches & Cellulose
- Diversity of Monosaccharides
Chain Length
Carbonyl: Aldo or Keto sugar
3D geometry: Right Handed or Left Handed Forms
Ring Formation generates a – “down” or b – “up” forms
- Table Sugar, Malt Sugar & Milk Sugar – Formation of Disaccharides
condensation dehydration reaction (reverse by “hydrolysis”)
sucrose, maltose and lactose – the geometry of “sweetness”
Where Sugars come from
- Starches – Polymers of Glucose Units
Amylose, Amylopectin & Glycogen
Starches Are Bland Not Sweet
- Why Don’t Polysaccharides Dissolve in Water?
- Making Gravy – Forcing Polysaccharides to Hydrogen Bond with Water
- Cooking Rice Noodles – Plumping Noodles by Hydrogen Bonding with Water
- Agarose – a Polysaccharide Completely Dissolved in Water?
Substituted Polysaccharides
Gel Formation
- Cartilage, Mucus, Carrageenan & Xanthan Gum
Companion: Lab Exercise 5 - Sugars, Gravy, Noodles & Thickening Agents (Carbohydrate Solubility & the Polymer Effect)
Chapter 6 – How Would You Like Your Eggs? – Changing Protein Structure
- What Are Proteins and What Do They Do?
Roles of Proteins
Proteins are Polymers Of Amino Acids
Common Features of Amino Acids
Formation of Polymer Chains – Peptide Linkage
another type of Condensation Dehydration Reaction
(opposite reaction is “hydrolysis”)
Length Range of Polypeptide Chains
- 20 Different Amino Acids Used to Make Polypeptides in Humans – Differ by R-Group Side Chain
Polar – Hydrophilic (6 amino acids)
Nonpolar – Hydrophobic (9 amino acids)
Carboxylic Acid – Polar and Negatively Charged at pH 7 (2 amino acids)
Nitrogen Base – Polar and Positively Charged at pH 7 (3 amino acids)
Proportions of Amino Acids Differ Between Proteins
- The Sequence of Amino Acids in the Polypeptide Chain – the Primary Structure of a Protein
- Some Amino Acids & Short Polypeptides Are Signal Molecules
Melatonin, Seratonin, MSG, Aspartame, Histidine, Adrenaline and Dopamine
The Runner’s High – Endorphins and Enkephalins
- Making Jello (Reprise) – Importance of Protein Secondary Structures
Hydrogen Bonding to the Polar Polypeptide Backbone
Internal Hydrogen Bonding – Form Secondary Structures of a Protein
a helix
b sheet
R-Group Side Chains Make the Surfaces of the Secondary Structures
- Folding in Three Dimensional Space – the Tertiary Structure of the Protein
Domains of a Protein Are Clusters of Secondary Structures
Some Proteins Are Made of Multiple Polypeptide Chains – Protein Quaternary Structure
- Forces Stabilizing the Tertiary Structure of the Protein
“Hydrophobic In” – “Polar Out”
“Molecular Clasps” – Ion Pairs forming “salt bridges”
Cross-bracing Provides Extra Stability
Sickle Cell Hemoglobin – The Importance of “Molecular Clasp” Salt Bridges
“Molecular Handcuffs” – “disulfide bonds”
“Handcuffing” Regions of a Polypeptide Together
“Handcuffing” Two Polypeptide Chains Together
How a Hair Permanent Works
- Many Ways to Cook Eggs – Protein Denaturation
Destabilization of the Native Tertiary Structure=
- Fried & Hard Boiled Eggs – Denaturation by Heat
Denatured Proteins Coagulate
- Silky Scrambled Eggs
Cream & Water Trapped in Protein Coagulates
- Soft & Runny Eggs – Why Don’t Yolks Harden As Fast As Egg Whites?
Egg White Composition - Uniformity
Egg Yolk Composition – Diverse Composition
- Poached Eggs – Uncoupling “Molecular Clasps” With Vinegar
Making Poached Eggs Instead of Egg-Drop Soup – the Role of pH
1000 Year Old Eggs – Denaturing Egg Proteins at Room Temperature
- Why Wash My Hands With Soap to Prevent Disease?
Destabilizing Protein Structure Using Soap Micelles
- Making Meringue – Using “Air” to Denature Egg White Proteins
The Role of Lemon Juice
Mechanical Sheer Stress
The Role of Air Bubbles
The Role of Table Sugar
Why Yolks Ruin the Day?
- Why Are Some Beers Cloudy When Chilled?
Companion: Lab Exercise 6 Eggs: Raw, Boiled, Scrambled, Poached or Meringue (Protein Structure, Protein Denaturation, Coagulation)
Chapter 7 - Got Milk? - Nature's Perfect Food
- What Is Milk?
A Well-Balanced Source of Nutrients Needed to Sustain Life
Water, Lipids, Carbohydrates, Proteins, Minerals and Vitamins
- Demystifying Milk Product Labels
“Raw” Milk
“Pasteurized” Milk
“UHT” Milk
Cream Rises to the Top
“Fat Globules” are Casein Micelles
Cream & Skimmed Milk
“Half & Half”
Whole Milk, Reduced-Fat Milk and “Non-Fat” Milk – Differ by % Fat Content
Homogenized Milk
- Making Butter from Heavy Cream
The Butter Churn Generates Mechanical Sheer Stress
Formation of the Butter Ball
Buttermilk
- Milk Sugar & Lactose-Free Milk
Lactose, Lactase & Lactose-Intolerance
- Milk Proteins
Types & Function of Casein Proteins
Types & Function of Whey Proteins
- The “Skin” on Hot Milk or Pudding
Denaturation of b-lactoglobulin – a Whey Protein
- Does Milk Really Help You Fall Asleep?
Casein “Bioactive” Peptide Fragments: Hypotensive Peptides, Casomorphin Peptides,
Immuno-stimulatory, Antimicrobial & Satiety-Inducing
- What is A2 Milk and Why Does It Cost More?
Amino Acid Sequence Variants of beta Casomorphin-7
1% of the human population experiences “intestinal inflammation”
Curds & Whey
Spoiled Milk
Sour Milk
Vinegar Denatures Caseins- remove “molecular clasps” below pH 4.6
“Curd Formation”
Liquid Whey
A Preserved Form of Nutrients That Lasts Longer Than Raw Milk
Making Yogurt – Probiotic Bacteria Cultures & Slow Denaturation of Caseins
Lactic Acid Bacteria – Consume Lactose - Produce Lactic Acid – Lower the pH
Forms Microscopic Curds
Making Cottage Cheese – Fast & Slow Denaturation of Caseins
Different Species of Probiotic Lactic Acid Bacteria Used
Use Rennet Enzyme to Remove the Kappa-Casein Tail – Quick Denaturation of Casein Proteins
Growth of Bacteria Lower pH – Further Denaturation of Casiens
Physical Shrinking – Heating and Cooling Curds
Making Cheddar Cheese from Cottage Cheese
Same Strains & Species of Probiotic Lactic Acid Bacteria Used
Further Heating and Cooling Curds
Salting Curds – Sodium Displacing Calcium
Pressing Curds – Squeezing Out the Whey
Aging Cheese – lowering the pH to “sharpen” the Cheese
Other Cheeses – Variation on a Theme
Different lactic acid bacteria strains make different cheeses – parmesan, mozzarella
Different types of probiotic bacterial species make different acids
Swiss Cheese -Proprionic Acid bacteria Produce CO2 Gas
Role of adjunct bacteria in “terroir” – distinctive “regional” flavors
Hard Cheeses & Soft Cheeses
What do you do with the Whey? – Sell It!
Nutrient Value of Whey Proteins
Companion: Lab Exercise 7 - Milk: Milk Fat, Pudding, Butter, Yogurt & Cheese (Fat Content, Lactose Content, Protein Denaturation & Separation)
Chapter 8 – What Happens When I Cook It?
- Boiling Brisket, Potatoes & Carrots – tenderizing foods by boiling
Why Meat is Tough – Collagen Fibers
Partial Depolymerization of Polymers by Hydrolysis
- Why Do Foods Turn Brown When Fried, Grilled, Baked or Barbequed?
The Maillard Reaction – Savory Taste - Why “Dark Russet” Potato Chips Are More Flavorful
The Caramelization Reaction
Enzymatic Browning – Phenolic Oxidation - A Plant Defense Reaction
- Fundamentals of Chemical Reactions
Swapping Partners - Rearrangement of Bonds
Proceeding From A High Potential Energy State to A Lower Potential Energy State
Releases Energy
- Enthalpy – The Oxidation States of Carbon
Reduced Hydrocarbons to Oxidized Carbons
- Entropy – Degrees of Freedom
Complex compounds to Simple Compounds - Polymers to Monomers
- Activation Energy – Destabilizing the Status Quo
- Enzyme Activity – Providing An Alternate Path – Many Small Steps
Binding Specificity – 3D Shape & Arrangement of Functional Groups
Alignment – All Collisions Are Productive Collisions
Physical Bond Strain – Leveraged Movement
Chemical Bond Strain – Teasing Apart the Status Quo
Using the Active Site to Attach
Regeneration & Reusability
- Use of Enzymes in Food Preparation
Tenderizing Steak
Making Holes in Jello
Enzymes have high specificity
Marinating Meats - Enzymes work optimally at specific pH
Enzyme Inhibition: heat, pH
Companion: Lab Exercise 8 - Meat Tenderizers, Pineapple, Apples & Jello-Reprise (Enzyme Action, Specificity & Inhibition)
Chapter 9 – What Happens When I Eat It?
- The Difference between Digestion & Metabolism
Digestion - Hydrolysis of Polymers Without Energy Capture
Metabolism – Energy Capture & Utilization
- A Tour of the Human Digestive System
Mouth
Esophagus
Stomach
Small Intestine – Duodenum, Jejunum & Ileum
Large Intestine – aka “Colon” or “Bowels”
- Metabolism – Energy Capture through Coupled Reactions
Energy Carriers
Carriers of Reducing Equivalents
- Food Labels - Comparing the Energy Content – The Oxidation States of Carbon (Reprise)
- Burning Fats & Carbs - Catabolic Reactions – Oxidation of food nutrients
Stepping Down the Oxidation States of Carbon
Oxidation of Fatty Acids
Oxidation of Glucose
TCA cycle Oxidations
Tally of ATPs Generated per Carbon from Equal Amounts of Fatty Acids, Glucose & Ethanol
- Moving, Pumping & Building - Anabolic Reactions – Doing Useful Work with Energy Captured
Building Polymers
Doing Useful Work - Movement, Pumping & Transport
Synthesizing Glucose
- Gaining Weight – Losing Weight
Short Term Energy Stores – Glycogen & Triglyceride Droplets – Liver & Muscle
Long Term Energy Stores – Adipose Cells – Triglyceride Droplets
Weight Loss Plans: Calories in – Calories Out
Importance of A High Protein Diet
- How A Low-Carb “Ketogenic” Diet Works
Calorie Deficit - Maximize use of triglycerides from fat cells to provide energy source
Minimize fluctuation of blood glucose levels
Production of Ketone Bodies – alternative fuel source – acidosis
- Other Weight Loss Strategies
Behavioral Modification - Calorie Counting – Portion Control
Appetite Suppressants
Beware of Dangerous “Fad Diets” – detrimental to health & potentially lethal
Companion: Lab Exercise 9 - Counting Calories - Energy Content of Foods (Energy Associated with Fats, Carbohydrates, Proteins & Exercise)
Chapter 10 – Why Breathe Oxygen & Life Without It
- Cashing in Reducing Equivalents
The Need to Constantly Recycle Carriers of Reducing Equivalents
- What O2 is Needed For
The Final Acceptor of “H2” to Make H2O + Energy
- Oxidative Phosphorylation
Oxidation of Reduced Carriers – Electron Transport Chain
The Force Behind the Dam - Generation of an H+ Gradient
Phosphorylation – the formation of ATP
The Whole Process Stops Without O2 – Cyanide
Keeping Warm with Brown Fat - Decoupling Agents
- Life Without Oxygen - Anaerobic Fermentation to Recycle Carriers of “H2”
Red & White Muscle
Burst Exercise - White Glycolytic Muscle - Sugar to Lactic Acid
Turning Sugar to Alcohol - Fermentation In Yeast - Sugar to Ethanol & CO2
Making Alcoholic “Hard” Cider
Alcohol Content of Beer, Cider, Wine & Champagne – mirrors sugar content
Distillation
Alcohol is Not a Diet Food - Long-Term Preservation of Calories from Perishable Foods
- The Unique Properties of Wheat Gluten
The Wheat Kernel – Germ, Endosperm & Bran
The Unusual Structure of Wheat Endosperm Proteins – Gliadin & Glutenin
Kneading Gluten – The Tangling of Glutenin & Gliadin – Tightened by NaCl
Comparison of Wheat Flour Dough to Rice Flour Dough
- Raising Dough - Leavening of Dough through Yeast Fermentation
Use of CO2 in leavening bread
Sugar, Temperature – Yeast are Alive
The Effects of Salt on Bread Texture
- Chemical Leavening of Cakes, Cookies, Pastries & Scones
Baking Soda & Vinegar or Cream of Tartar – Fast Acting Leavening Agents
Baking Soda and Baking Powder – Why Cookies Plump Up When You Bake Them
Uniformity of Texture
Companion: Lab Exercise 10 - Raising Dough - Making Bread & Turning Sugar Water into Wine & Vinegar (Leavening Agents, Yeast Fermentation, Oxidation, & Gluten in Pizza Dough)
Chapter 11 – Food Safety, Food Preservation & Human Health
Another Lettuce Recall? – Food-Borne Pathogens
- Why Foods Spoil
Nutrient Source for Various Organisms
- Food-Borne Diseases
E. coli O157 H7, Salmonella, Campylobacter, Listeria, Staph (Staphlycoccus), Shigella,
Cyclospora, Clostridium,Norovirus
Sources of Pathogens in Foods
- What Makes a Pathogen?
Toxins"
Biofilms
Population Density – Quorum Sensing"
- Food Safety Hygiene
- Bacterial Growth
Fission Produces Daughter Cells
Logarithmic Growth – 21 generations produces 2 million daughter cells
Effect of Temperature
- Detection of Bacteria by Growth on Agar Plates
Identifying Types of Bacteria
Estimating Population Size by Serial Dilution
Identifying Bacteria in Your Household – They’re Everywhere
The Effect of Cleaning Kitchen Surfaces & Hands
Why Sell Me a Half-Empty Bag of Potato Chips? - Food Preservation Strategies
Cooking
Drying
Salting
Freezing & Flash-Freezing
Freeze-Drying
Mylar Packaging
Alternate Atmosphere Packaging
Canning
Pasteurized Cheese – the Kraft Process
Irradiated Foods
Pickled Foods
Lactate, Vinegar & Salt
Storage in Alcohol – Tinctures of Alcohol
The Human Microbiome – Bacteria & Us
- Bacteria & Other Microbes Live in Partnership With Us
All “Exterior” Surfaces – Including Digestive Tract
10x Microbial Cells as Human Cells
Type & Proportion of Microbes
- How Identify Bacterial Species & Abundance
DNA Typing
- Perturbation of Microbial Populations & Opportunistic Pathogens
Burn Victims & Pseudomonas
Acne
- Beneficial Actions of Probiotic Bacteria of the Colon
Physical Colonization – Exclusion of Pathogens
Modified Environment – Exclusion of Pathogens
Production of Useful Substances - Vitamins, Anti-inflammatory, Immune Stimulants &
Antimicrobial Compounds
- Microbial Populations in Human Colon Can Vary With
Disease state (correlation – uncertain if cause or effect)
Age/Life Stage
Diet
Hormone fluctuations
Stress
Medicinal Drugs, especially antibiotics
Ancestral Genetics
- Probiotic Foods & Supplements
Foods Containing Live Cultures of Lactic Acid Bacteria
- Prebiotic Foods & Supplements
" Nutrient Sources for Probiotic Bacteria - Dietary Fiber, Oligosaccharides, Pectin &
Polyphenols
Companion: Lab Exercise 11 - Safe at the Plate - Food Safety (Presence of Bacteria in the Kitchen and on Foods; Bacterial Detection, Growth Rate & Doubling Time)
Lab Report Answers
Sample Exam Questions
Sources
References
Index
Mike Vayda’s passion to understand the world around him led him to become a research scientist. His various research projects and collaborations focused on the molecular and biochemical mechanisms of responding to extreme environmental conditions, such as low oxygen stress and cold stress. Administrative appointments provided him with the opportunity to engage with the general public on science matters, particularly the science of foods.
Dr. Vayda grew up in the small suburban town of Cresskill, New Jersey, just across the Hudson River from New York City. The Gemini and Apollo space programs piqued young Vayda’s interest in science which was further nurtured by weekend visits to the Jersey Shore. As a first-generation college student, he attended the University of New Hampshire where he earned a bachelor of science in biochemistry and a bachelor of arts in zoology. He pursued graduate training at Princeton University under the tutelage of Dr. S. Jane Flint, earning his master’s degree in biochemical sciences and his PhD in molecular biology. He received an NIH postdoctoral fellowship to conduct research at the University of California Berkeley. He taught and conducted research as a faculty member at the University of Maine, progressing from an assistant professor to a tenured associate professor and then full professor. He then pursued an administrative career as an assistant director of the Maine Agricultural and Forest Experiment Station at the University of Maine, as the associate dean of the College of Agriculture and Life Sciences at the University of Vermont, as dean of the Bumpers College of Agricultural, Food and Life Sciences at the University of Arkansas, and as provost at the University of Massachusetts Lowell. He is currently a professor of biological sciences at the University of Massachusetts Lowell.
Dr. Vayda is grateful to have engaged in scientific collaborations that have extended across the United States from New England to the Great Plains to California, and from Europe to South Africa, China, and Antarctica. The fundamentally human experience with foods, and the human cultures that have developed food products, are one of his passionate interests.
Biochemistry in the Kitchen is designed for an introductory one-semester course for nonscience students who need to fulfill a requirement for a “lab-science course.” The intent is to provide these students with a robust understanding of biochemical phenomena illustrated in the context of cooking and other practical everyday experiences in the world around them. The book is “self-contained,” assuming only minimal previous exposure to science courses in middle school or junior high school. Questions are posed such as “What happens during cooking?,” “Why does that happen?,” and “How does that work?” Scientific concepts necessary to understand the observed phenomena are presented, and answer these questions in a sequential order, starting with “first principles” in the early chapters and adding new information that builds on the initial concepts to explain more complicated phenomenon. Scientific jargon is avoided wherever possible, instead using “common terms” to explain what is happening. The book is accompanied by online “Laboratory Experiments” that can be conducted in the students’ home, kitchen, or classroom. As such, this course is appropriate for use at the introductory college level or high school level.
Students who successfully complete Biochemistry in the Kitchen will be able to:
- Demonstrate a fundamental understanding of the principle concepts of biochemistry and be able to communicate scientific ideas effectively using common everyday terms and experiences to illustrate concepts.
- Understand the scientific method and be able to apply scientific reasoning to investigate questions, solve problems, and form conclusions.
- Be able to understand the fundamental role that water plays in biochemical processes, with particular application to food chemistry and cooking practices.
- Evaluate scientific data, develop hypotheses, interpret results, and apply this information to applications involving cooking, emulsifications, acid/base buffering action, hydration of polymers, denaturation of proteins, catalysis by enzymes, human metabolism, fermentation, food safety, and bacterial growth.
- Display an understanding of food ingredients and their purpose.
- Communicate what chemical transformations occur during cooking, explain why humans cook food, and how humans obtain energy from eating foods.
Organization
There are eleven broad topics addressed in this book, organized into four modules.
Biochemistry cannot be understood without understanding the properties of water. Accordingly, the four chapters which constitute the first module explain the peculiarities of water and how we experience these properties of water in our everyday lives, explaining phenomena such as the following:
- Why cooking with steam is more effective than cooking with boiling water?
- Why cooling a hot beverage with ice is more effective than using cold water?
- What is wind chill?
- Why do oil and water separate into distinct layers?
- What are saturated fats, unsaturated fats, and omega 3 fats?
- How does soap work?
- How is mayonnaise made?
- Why is phosphoric acid or citric acid added to so many foods?
- Why do we breathe fast when we exercise?
The four chapters comprising the second module describe biological polymers, specifically, polysaccharides and proteins. The behavior of these polymers in water explains the structures these polymers form and what happens to these polymers when we prepare the foods that we eat. For examples, topics addressed in the second module include the following:
- Why is sugar sweet but starch made out of sugar units is not?
- Why are some kinds of sugars sweeter than others?
- What happens to starch while making gravy?
- Why do noodles take on water when heated?
- Why does clear liquid “egg white” turn into a solid white gel when heated?
- Why is vinegar added to water when making poached eggs?
- How do you make meringue out of egg whites without cooking?
- How do you make yogurt, cheese, and butter out of milk?
- Why do meats become tender when you boil them in water?
- Why do foods turn brown when you cook them?
- What do meat tenderizers and meat marinades do?
The third module describes what happens to biological polymers when we eat them, and how humans capture energy from the food nutrients that we eat. These chapters address the following:
- What is the difference between digestion and metabolism?
- Why do foods high in fats have a higher calorie content than do foods made primarily of starches or proteins?
- How do we get energy out of these foods?
- How does the Keto diet work?
- Why do we need oxygen to live?
- How is beer, wine, and vinegar made?
- Why is wheat “gluten” in so many foods?
- Why does bread rise when leavened?
- Why do cookies rise when baked in the oven?
The last module includes a chapter on food safety, bacterial growth, why foods spoil, and why some bacteria cause food-borne illnesses. There is a chapter discussing the various techniques humans have developed over the centuries to preserve foods and how those processes work to suppress microbial processes. The final chapter introduces the concept of the human microbiome—the bacteria that live in partnership with humans that are essential to keep us healthy. Some of the questions addressed in this fourth module include the following:
- Why do we chill foods to prevent spoilage?
- Food recalls: Where do food-borne illnesses come from?
- Why can some foods be stored at room temperature?
- Why are bags of corn chips or potato chips sold “half-empty”?
- What are probiotic bacteria? What is a prebiotic food?
When I was a university provost, I often heard complaints from students and their deans that the science courses intended for nonscience majors were “boring,” “over their heads,” “tedious,” or “irrelevant to their lives.” They wanted something “different,” something that would be useful to everyday life. When I returned to a faculty role, I committed myself to the endeavor of developing a “real science” course that would be meaningful to most people and present information to students in such a way that it would be readily understandable and applicable such that they would remember the basis of these biochemical phenomena throughout their lives. The most rewarding feedback that I have received from students are vignettes they tell me months or years later describing how they recalled at work why they used lemon juice in making guacamole or on vacation why lemon juice removes fish odor off their hands. I hope you have the same delightful experience with this book!
Preface
Purpose & Intent
Chapter 1 – A Recipe for Making Jello - Hypothesis Testing & The Scientific Method
Real Science is not just “Memorizing Facts”
Establishing Scientific “Facts”
- Making Sense of Observations
- Drawing on Past Experience
- Possible Explanations – Hypotheses
- Identifying Variables
- Hypothesis Testing
- Hypothesis Refinement
- Reproducibility – “Accepted Fact”
Companion: Lab Exercise 1 - Making Jello - Hypothesis Testing (The Scientific Method)
Chapter 2 - What’s So Special About Water ? – The Power of Hydrogen Bonding
- Liquid Water, Gaseous Steam, Solid Ice
- Atoms, Molecules & Hydrogen Bonding
- Types of Chemical Bonding:
Ionic – Theft & Abandonment
Covalent - Sharing
Polar Covalent – Some Atoms Share More Equally Than Others
- Boiling Water & Making Tea – Cooking & Cooling Energy in Hydrogen Bonds
Latent Heat of Phase Changes – Energy Needed to Break Hydrogen Bonds
- Why Blow on Hot Soup to Cool It?
Wind Chill
- Why Do Popcorn Kernels “Pop” When Heated?
- Making Tea - Plain or With Sugar & Lemon?
Substance that are Soluble in Water Form Hydrogen Bonds
Types of Polar Molecules
Ions are Hydrated by Layer of Water Molecules
Companion: Lab Exercise 2 - Tea, Eggs & Popcorn - Steam, Water & Ice (Hydrogen Bonding, Latent Energies of Vaporization & Freezing, Solubility)
Chapter 3 - Oil & Water Don’t Mix – Behavior of Nonpolar Molecules - “Hydrophobicity”
Nonpolar Molecules
- Hydrophobicity
- Why Does Italian Dressing (Oil, Water & Vinegar) Separate into Two Layers
Understanding Entropy by Playing Dice
- Why Does the Separation Occur Faster at Hot Temperature and Slower at Cold Temperature?"
Temperature Multiples the Effect of Entropy
- Demystifying Food Labels - What are Saturated, Unsaturated, Cis, Trans & Omega Fats?
Types of Types of Hydrophobic Molecules in Nature (non-living things) - Hydrocarbons
Types of Nonpolar Hydrophobic Molecules in Living Organisms – Triglycerides: Fats & Oils
Liquid or Solid? Effect of Chain Length, Double Bonds & Cholesterol
- Comparing Food Labels & Melting Temperature
% Saturated, % Unsaturated, % Polyunsaturated & Presence of Cholesterol
- What’s the Difference Between Butter and Margarine?
Partial Hydrogenation & Trans Fats
- The Perils of Advertising – Some Naturally-Occurring Trans Fats Are Good For You
- What’s All This Chatter about Omega 3’s and Omega 6’s – What are they?
Getting Oil & Water to Emulsify
- How Soap Works
Free Fatty Acids are Amphipathic Molecules
Blowing Bubbles
Washing Greasy Dinner Dishes – Making Micelles – Emulsification
- How is Soap Made?
- Why are Mono- and Di-glycerides in my Ice Cream?
- Making Mayonnaise – Emulsifiers in Egg Yolk
- Summary – Types of Lipids
- Why is there so much Lecithin in Egg Yolk?
Phospholipid Bilayers and Cell Membranes
- LDL and HDL - An Important Role for Phospholipid Micelles in Human Blood
Companion: Lab Exercise 3 - Italian Dressing, Probability, Soap & Mayonnaise (Hydrophobicity, Entropy & Emulsifiers)
Chapter 4 - Buffering Against Change – pH, acids, bases, and buffering agents
- The 2nd Special Property of Water – transient ionization
- Do You Have A Mole?
Comparing Equal Numbers of Things With Different Weights
- pH, Acids & Bases
Measuring H+ concentration
Measuring –OH concentration
- pH of Various Foods and Household Substances
- Vinegar & Ammonia – transient ionization of weak acids and bases
Carboxylic Acids
Amine Groups
- Why Use Lemon With Lobster or Fish?
Tipping the Balance with pH
- The “Balance Point” Between the Charged Ionic Form and the Uncharged Molecular Form
- Acetate, Citrate, Phosphate & Bicarbonate - Why are these Chemicals in in My Food
Buffers Resist Change in pH
- Why Do You Breathe Rapidly During Exercise?
Sodium Bicarbonate
Companion: Lab Exercise 4 - pH of Foods - Vinegar, Ammonia & Baking Soda (Acids, Bases, pH, and Buffering Capacity)
Chapter 5 - Carb Up! - Why Sugar is Sweet but Starch is Not – Carbohydrates
- Human Blood Glucose Levels
- Types of Carbohydrates
Monomers - Monosaccharides
Dimers - Disaccharides
Polysaccharides; Starches & Cellulose
- Diversity of Monosaccharides
Chain Length
Carbonyl: Aldo or Keto sugar
3D geometry: Right Handed or Left Handed Forms
Ring Formation generates a – “down” or b – “up” forms
- Table Sugar, Malt Sugar & Milk Sugar – Formation of Disaccharides
condensation dehydration reaction (reverse by “hydrolysis”)
sucrose, maltose and lactose – the geometry of “sweetness”
Where Sugars come from
- Starches – Polymers of Glucose Units
Amylose, Amylopectin & Glycogen
Starches Are Bland Not Sweet
- Why Don’t Polysaccharides Dissolve in Water?
- Making Gravy – Forcing Polysaccharides to Hydrogen Bond with Water
- Cooking Rice Noodles – Plumping Noodles by Hydrogen Bonding with Water
- Agarose – a Polysaccharide Completely Dissolved in Water?
Substituted Polysaccharides
Gel Formation
- Cartilage, Mucus, Carrageenan & Xanthan Gum
Companion: Lab Exercise 5 - Sugars, Gravy, Noodles & Thickening Agents (Carbohydrate Solubility & the Polymer Effect)
Chapter 6 – How Would You Like Your Eggs? – Changing Protein Structure
- What Are Proteins and What Do They Do?
Roles of Proteins
Proteins are Polymers Of Amino Acids
Common Features of Amino Acids
Formation of Polymer Chains – Peptide Linkage
another type of Condensation Dehydration Reaction
(opposite reaction is “hydrolysis”)
Length Range of Polypeptide Chains
- 20 Different Amino Acids Used to Make Polypeptides in Humans – Differ by R-Group Side Chain
Polar – Hydrophilic (6 amino acids)
Nonpolar – Hydrophobic (9 amino acids)
Carboxylic Acid – Polar and Negatively Charged at pH 7 (2 amino acids)
Nitrogen Base – Polar and Positively Charged at pH 7 (3 amino acids)
Proportions of Amino Acids Differ Between Proteins
- The Sequence of Amino Acids in the Polypeptide Chain – the Primary Structure of a Protein
- Some Amino Acids & Short Polypeptides Are Signal Molecules
Melatonin, Seratonin, MSG, Aspartame, Histidine, Adrenaline and Dopamine
The Runner’s High – Endorphins and Enkephalins
- Making Jello (Reprise) – Importance of Protein Secondary Structures
Hydrogen Bonding to the Polar Polypeptide Backbone
Internal Hydrogen Bonding – Form Secondary Structures of a Protein
a helix
b sheet
R-Group Side Chains Make the Surfaces of the Secondary Structures
- Folding in Three Dimensional Space – the Tertiary Structure of the Protein
Domains of a Protein Are Clusters of Secondary Structures
Some Proteins Are Made of Multiple Polypeptide Chains – Protein Quaternary Structure
- Forces Stabilizing the Tertiary Structure of the Protein
“Hydrophobic In” – “Polar Out”
“Molecular Clasps” – Ion Pairs forming “salt bridges”
Cross-bracing Provides Extra Stability
Sickle Cell Hemoglobin – The Importance of “Molecular Clasp” Salt Bridges
“Molecular Handcuffs” – “disulfide bonds”
“Handcuffing” Regions of a Polypeptide Together
“Handcuffing” Two Polypeptide Chains Together
How a Hair Permanent Works
- Many Ways to Cook Eggs – Protein Denaturation
Destabilization of the Native Tertiary Structure=
- Fried & Hard Boiled Eggs – Denaturation by Heat
Denatured Proteins Coagulate
- Silky Scrambled Eggs
Cream & Water Trapped in Protein Coagulates
- Soft & Runny Eggs – Why Don’t Yolks Harden As Fast As Egg Whites?
Egg White Composition - Uniformity
Egg Yolk Composition – Diverse Composition
- Poached Eggs – Uncoupling “Molecular Clasps” With Vinegar
Making Poached Eggs Instead of Egg-Drop Soup – the Role of pH
1000 Year Old Eggs – Denaturing Egg Proteins at Room Temperature
- Why Wash My Hands With Soap to Prevent Disease?
Destabilizing Protein Structure Using Soap Micelles
- Making Meringue – Using “Air” to Denature Egg White Proteins
The Role of Lemon Juice
Mechanical Sheer Stress
The Role of Air Bubbles
The Role of Table Sugar
Why Yolks Ruin the Day?
- Why Are Some Beers Cloudy When Chilled?
Companion: Lab Exercise 6 Eggs: Raw, Boiled, Scrambled, Poached or Meringue (Protein Structure, Protein Denaturation, Coagulation)
Chapter 7 - Got Milk? - Nature's Perfect Food
- What Is Milk?
A Well-Balanced Source of Nutrients Needed to Sustain Life
Water, Lipids, Carbohydrates, Proteins, Minerals and Vitamins
- Demystifying Milk Product Labels
“Raw” Milk
“Pasteurized” Milk
“UHT” Milk
Cream Rises to the Top
“Fat Globules” are Casein Micelles
Cream & Skimmed Milk
“Half & Half”
Whole Milk, Reduced-Fat Milk and “Non-Fat” Milk – Differ by % Fat Content
Homogenized Milk
- Making Butter from Heavy Cream
The Butter Churn Generates Mechanical Sheer Stress
Formation of the Butter Ball
Buttermilk
- Milk Sugar & Lactose-Free Milk
Lactose, Lactase & Lactose-Intolerance
- Milk Proteins
Types & Function of Casein Proteins
Types & Function of Whey Proteins
- The “Skin” on Hot Milk or Pudding
Denaturation of b-lactoglobulin – a Whey Protein
- Does Milk Really Help You Fall Asleep?
Casein “Bioactive” Peptide Fragments: Hypotensive Peptides, Casomorphin Peptides,
Immuno-stimulatory, Antimicrobial & Satiety-Inducing
- What is A2 Milk and Why Does It Cost More?
Amino Acid Sequence Variants of beta Casomorphin-7
1% of the human population experiences “intestinal inflammation”
Curds & Whey
Spoiled Milk
Sour Milk
Vinegar Denatures Caseins- remove “molecular clasps” below pH 4.6
“Curd Formation”
Liquid Whey
A Preserved Form of Nutrients That Lasts Longer Than Raw Milk
Making Yogurt – Probiotic Bacteria Cultures & Slow Denaturation of Caseins
Lactic Acid Bacteria – Consume Lactose - Produce Lactic Acid – Lower the pH
Forms Microscopic Curds
Making Cottage Cheese – Fast & Slow Denaturation of Caseins
Different Species of Probiotic Lactic Acid Bacteria Used
Use Rennet Enzyme to Remove the Kappa-Casein Tail – Quick Denaturation of Casein Proteins
Growth of Bacteria Lower pH – Further Denaturation of Casiens
Physical Shrinking – Heating and Cooling Curds
Making Cheddar Cheese from Cottage Cheese
Same Strains & Species of Probiotic Lactic Acid Bacteria Used
Further Heating and Cooling Curds
Salting Curds – Sodium Displacing Calcium
Pressing Curds – Squeezing Out the Whey
Aging Cheese – lowering the pH to “sharpen” the Cheese
Other Cheeses – Variation on a Theme
Different lactic acid bacteria strains make different cheeses – parmesan, mozzarella
Different types of probiotic bacterial species make different acids
Swiss Cheese -Proprionic Acid bacteria Produce CO2 Gas
Role of adjunct bacteria in “terroir” – distinctive “regional” flavors
Hard Cheeses & Soft Cheeses
What do you do with the Whey? – Sell It!
Nutrient Value of Whey Proteins
Companion: Lab Exercise 7 - Milk: Milk Fat, Pudding, Butter, Yogurt & Cheese (Fat Content, Lactose Content, Protein Denaturation & Separation)
Chapter 8 – What Happens When I Cook It?
- Boiling Brisket, Potatoes & Carrots – tenderizing foods by boiling
Why Meat is Tough – Collagen Fibers
Partial Depolymerization of Polymers by Hydrolysis
- Why Do Foods Turn Brown When Fried, Grilled, Baked or Barbequed?
The Maillard Reaction – Savory Taste - Why “Dark Russet” Potato Chips Are More Flavorful
The Caramelization Reaction
Enzymatic Browning – Phenolic Oxidation - A Plant Defense Reaction
- Fundamentals of Chemical Reactions
Swapping Partners - Rearrangement of Bonds
Proceeding From A High Potential Energy State to A Lower Potential Energy State
Releases Energy
- Enthalpy – The Oxidation States of Carbon
Reduced Hydrocarbons to Oxidized Carbons
- Entropy – Degrees of Freedom
Complex compounds to Simple Compounds - Polymers to Monomers
- Activation Energy – Destabilizing the Status Quo
- Enzyme Activity – Providing An Alternate Path – Many Small Steps
Binding Specificity – 3D Shape & Arrangement of Functional Groups
Alignment – All Collisions Are Productive Collisions
Physical Bond Strain – Leveraged Movement
Chemical Bond Strain – Teasing Apart the Status Quo
Using the Active Site to Attach
Regeneration & Reusability
- Use of Enzymes in Food Preparation
Tenderizing Steak
Making Holes in Jello
Enzymes have high specificity
Marinating Meats - Enzymes work optimally at specific pH
Enzyme Inhibition: heat, pH
Companion: Lab Exercise 8 - Meat Tenderizers, Pineapple, Apples & Jello-Reprise (Enzyme Action, Specificity & Inhibition)
Chapter 9 – What Happens When I Eat It?
- The Difference between Digestion & Metabolism
Digestion - Hydrolysis of Polymers Without Energy Capture
Metabolism – Energy Capture & Utilization
- A Tour of the Human Digestive System
Mouth
Esophagus
Stomach
Small Intestine – Duodenum, Jejunum & Ileum
Large Intestine – aka “Colon” or “Bowels”
- Metabolism – Energy Capture through Coupled Reactions
Energy Carriers
Carriers of Reducing Equivalents
- Food Labels - Comparing the Energy Content – The Oxidation States of Carbon (Reprise)
- Burning Fats & Carbs - Catabolic Reactions – Oxidation of food nutrients
Stepping Down the Oxidation States of Carbon
Oxidation of Fatty Acids
Oxidation of Glucose
TCA cycle Oxidations
Tally of ATPs Generated per Carbon from Equal Amounts of Fatty Acids, Glucose & Ethanol
- Moving, Pumping & Building - Anabolic Reactions – Doing Useful Work with Energy Captured
Building Polymers
Doing Useful Work - Movement, Pumping & Transport
Synthesizing Glucose
- Gaining Weight – Losing Weight
Short Term Energy Stores – Glycogen & Triglyceride Droplets – Liver & Muscle
Long Term Energy Stores – Adipose Cells – Triglyceride Droplets
Weight Loss Plans: Calories in – Calories Out
Importance of A High Protein Diet
- How A Low-Carb “Ketogenic” Diet Works
Calorie Deficit - Maximize use of triglycerides from fat cells to provide energy source
Minimize fluctuation of blood glucose levels
Production of Ketone Bodies – alternative fuel source – acidosis
- Other Weight Loss Strategies
Behavioral Modification - Calorie Counting – Portion Control
Appetite Suppressants
Beware of Dangerous “Fad Diets” – detrimental to health & potentially lethal
Companion: Lab Exercise 9 - Counting Calories - Energy Content of Foods (Energy Associated with Fats, Carbohydrates, Proteins & Exercise)
Chapter 10 – Why Breathe Oxygen & Life Without It
- Cashing in Reducing Equivalents
The Need to Constantly Recycle Carriers of Reducing Equivalents
- What O2 is Needed For
The Final Acceptor of “H2” to Make H2O + Energy
- Oxidative Phosphorylation
Oxidation of Reduced Carriers – Electron Transport Chain
The Force Behind the Dam - Generation of an H+ Gradient
Phosphorylation – the formation of ATP
The Whole Process Stops Without O2 – Cyanide
Keeping Warm with Brown Fat - Decoupling Agents
- Life Without Oxygen - Anaerobic Fermentation to Recycle Carriers of “H2”
Red & White Muscle
Burst Exercise - White Glycolytic Muscle - Sugar to Lactic Acid
Turning Sugar to Alcohol - Fermentation In Yeast - Sugar to Ethanol & CO2
Making Alcoholic “Hard” Cider
Alcohol Content of Beer, Cider, Wine & Champagne – mirrors sugar content
Distillation
Alcohol is Not a Diet Food - Long-Term Preservation of Calories from Perishable Foods
- The Unique Properties of Wheat Gluten
The Wheat Kernel – Germ, Endosperm & Bran
The Unusual Structure of Wheat Endosperm Proteins – Gliadin & Glutenin
Kneading Gluten – The Tangling of Glutenin & Gliadin – Tightened by NaCl
Comparison of Wheat Flour Dough to Rice Flour Dough
- Raising Dough - Leavening of Dough through Yeast Fermentation
Use of CO2 in leavening bread
Sugar, Temperature – Yeast are Alive
The Effects of Salt on Bread Texture
- Chemical Leavening of Cakes, Cookies, Pastries & Scones
Baking Soda & Vinegar or Cream of Tartar – Fast Acting Leavening Agents
Baking Soda and Baking Powder – Why Cookies Plump Up When You Bake Them
Uniformity of Texture
Companion: Lab Exercise 10 - Raising Dough - Making Bread & Turning Sugar Water into Wine & Vinegar (Leavening Agents, Yeast Fermentation, Oxidation, & Gluten in Pizza Dough)
Chapter 11 – Food Safety, Food Preservation & Human Health
Another Lettuce Recall? – Food-Borne Pathogens
- Why Foods Spoil
Nutrient Source for Various Organisms
- Food-Borne Diseases
E. coli O157 H7, Salmonella, Campylobacter, Listeria, Staph (Staphlycoccus), Shigella,
Cyclospora, Clostridium,Norovirus
Sources of Pathogens in Foods
- What Makes a Pathogen?
Toxins"
Biofilms
Population Density – Quorum Sensing"
- Food Safety Hygiene
- Bacterial Growth
Fission Produces Daughter Cells
Logarithmic Growth – 21 generations produces 2 million daughter cells
Effect of Temperature
- Detection of Bacteria by Growth on Agar Plates
Identifying Types of Bacteria
Estimating Population Size by Serial Dilution
Identifying Bacteria in Your Household – They’re Everywhere
The Effect of Cleaning Kitchen Surfaces & Hands
Why Sell Me a Half-Empty Bag of Potato Chips? - Food Preservation Strategies
Cooking
Drying
Salting
Freezing & Flash-Freezing
Freeze-Drying
Mylar Packaging
Alternate Atmosphere Packaging
Canning
Pasteurized Cheese – the Kraft Process
Irradiated Foods
Pickled Foods
Lactate, Vinegar & Salt
Storage in Alcohol – Tinctures of Alcohol
The Human Microbiome – Bacteria & Us
- Bacteria & Other Microbes Live in Partnership With Us
All “Exterior” Surfaces – Including Digestive Tract
10x Microbial Cells as Human Cells
Type & Proportion of Microbes
- How Identify Bacterial Species & Abundance
DNA Typing
- Perturbation of Microbial Populations & Opportunistic Pathogens
Burn Victims & Pseudomonas
Acne
- Beneficial Actions of Probiotic Bacteria of the Colon
Physical Colonization – Exclusion of Pathogens
Modified Environment – Exclusion of Pathogens
Production of Useful Substances - Vitamins, Anti-inflammatory, Immune Stimulants &
Antimicrobial Compounds
- Microbial Populations in Human Colon Can Vary With
Disease state (correlation – uncertain if cause or effect)
Age/Life Stage
Diet
Hormone fluctuations
Stress
Medicinal Drugs, especially antibiotics
Ancestral Genetics
- Probiotic Foods & Supplements
Foods Containing Live Cultures of Lactic Acid Bacteria
- Prebiotic Foods & Supplements
" Nutrient Sources for Probiotic Bacteria - Dietary Fiber, Oligosaccharides, Pectin &
Polyphenols
Companion: Lab Exercise 11 - Safe at the Plate - Food Safety (Presence of Bacteria in the Kitchen and on Foods; Bacterial Detection, Growth Rate & Doubling Time)
Lab Report Answers
Sample Exam Questions
Sources
References
Index
Mike Vayda’s passion to understand the world around him led him to become a research scientist. His various research projects and collaborations focused on the molecular and biochemical mechanisms of responding to extreme environmental conditions, such as low oxygen stress and cold stress. Administrative appointments provided him with the opportunity to engage with the general public on science matters, particularly the science of foods.
Dr. Vayda grew up in the small suburban town of Cresskill, New Jersey, just across the Hudson River from New York City. The Gemini and Apollo space programs piqued young Vayda’s interest in science which was further nurtured by weekend visits to the Jersey Shore. As a first-generation college student, he attended the University of New Hampshire where he earned a bachelor of science in biochemistry and a bachelor of arts in zoology. He pursued graduate training at Princeton University under the tutelage of Dr. S. Jane Flint, earning his master’s degree in biochemical sciences and his PhD in molecular biology. He received an NIH postdoctoral fellowship to conduct research at the University of California Berkeley. He taught and conducted research as a faculty member at the University of Maine, progressing from an assistant professor to a tenured associate professor and then full professor. He then pursued an administrative career as an assistant director of the Maine Agricultural and Forest Experiment Station at the University of Maine, as the associate dean of the College of Agriculture and Life Sciences at the University of Vermont, as dean of the Bumpers College of Agricultural, Food and Life Sciences at the University of Arkansas, and as provost at the University of Massachusetts Lowell. He is currently a professor of biological sciences at the University of Massachusetts Lowell.
Dr. Vayda is grateful to have engaged in scientific collaborations that have extended across the United States from New England to the Great Plains to California, and from Europe to South Africa, China, and Antarctica. The fundamentally human experience with foods, and the human cultures that have developed food products, are one of his passionate interests.