The Western Diet (Engineered
Foods)
Why Do We Process Foods?
How Do We Process Foods?
Evolution
Evolutionary Discordance
Where did the Western Diet Start?
• 10 000 years ago
• Introduction of agriculture and Food
Engineering
• Introduction of animal husbandry
New Food Stuff
• 70% of our daily energy intake was unavailable
prior to the industrial revolution
– Refined sugar
– Refined vegetable oil
– Cereals
– Diary products
– Alcohol
– Mixed foods, Canned Foods, Frozen Foods
• Cookies, pizza, soft drinks, ice cream...etc!!!!
Lets Look at Unit Operations and
Consequences?
• Simplest Unit Operation
– Size Reduction
– Increased Functionality i.e., starch from granule
– Increased shelf life i.e. sugar from sugar cane
– Used as ingredients i.e., vegetable oils
Milling
• Separate the endosperm from the bran and
germ
Brown Rice
White Rice % REMOVED
Dietary Fiber
3.32 g
0.74 g
Vitamin E
1.4 mg
0.462 mg
72.2 mg
22.6 mg
10 mcg
4.1 mcg
Thiamin (B1)
0.223 mg
0.176 mg
Riboflavin (B2)
0.039 mg
0.021 mg
Niacin (B3)
2.730 mg
2.050 mg
Vitamin B6
0.294 mg
0.103 mg
26 mg
19 mg
Magnesium
Folacin
Selenium
78%
67%
69%
59%
21%
46%
14%
69%
27%
3.5% of our energy is from whole grains
20.4% of our energy is from refined grains
Refined Sugar
•
•
•
•
•
•
Crystalline sugar 500BC
Pre 500BC honey was consumed
Typical consumption <1kg per capita
Post industrial revolution 6.8kg per capita
Currently 69kg per capita
Now there is high fructose corn syrups and
other artificial sweeteners
Refined Sugars
• Average American consumes 2-3 pounds of
sugar each week
• One of sugar's major drawbacks is that it
raises the insulin level, which in turn
depresses the immune system.
– This is not something you want to take place if you
want to avoid disease.
Refined vegetable oils
• From 1909 to 1999
• 130% increase in the consumption of salad
and cooking oils
• 140% increase in the consumption of
shortening
• 410% increase in the consumption of
margarine
2nd Unit Operation -- Hydrogenation
• Produce what was thought to be novel trans
fatty acid isomers
• Trans elaidic acid only occurs in hydrogenated
food stuff
• One of the food industries largest mistakes.
Butter Vs. Margarine?
Most Common Unit Operation
Thermal Processing
• Commonly applied during food processing
• Severity of the process (amount of heat
applied) is a function of both time and
temperature
– This minimizes nutrient loss
– Minimizes reduction in product quality
– Minimizes energy consumption
Thermal Processing
• Most widely applied unit operation in food
processing
• Fundamental aspects
– Involves the application of heat
– Amount of heat added is a function of time and
temperature
– Preservative effects largely due to denaturation of
protein
Types of Thermal Processing
•
•
•
•
Cooking
Blanching
Pasteurization
Sterilization
Cooking
• Primary objective: to increase palatability
– Baking, roasting - dry heat, 150-200°C
– Boiling, stewing, steaming - boiling water to
steam (~100°C)
– Frying with or without oil, 175 to 225°C
• Some preservative changes
– Destruction of some spoilage and all
pathogenic microorganisms
– Inactivation of deteriorative enzymes
– Reduction of water
Cooking
• Other desirable changes
– Inactivation of some antinutritional factors
• avidin in egg white which
binds biotin (B7)
• hemagglutinins in kidney and
wax beans
– agglutination of red blood cells
• Improved digestibility of
some food constituents
Cooking
• Undesirable changes
– Loss of nutrients
• Oxidation of unsaturated lipids
• Degradation of antioxidants
– Decline in sensory quality with excessive heating
• Non enzymatic Browning—toast and maple syrup
Nutrient Loss
• Lysine bio -availability reduced by nonenzymatic browning
• Heat sensitive vitamins—decreases
bioavailability not concentration
– Vitamin A, Carotenes, Vitamin D
• Water leaching vitamins-decreases
concentration not bioavailability
– Thiamine, Niacin, Folate,
Blanching
• Prior to drying of fruits
• Primary objective
– Inactivate deteriorative enzymes
– Also kills some spoilage bacteria (reduces microbial load)
• Commercially
– Atmospheric steam or boiling water (~100°C)
– Pressurized steam or hot gas (>100°C)
• Less severe process than canning for example
Water Vs Steam Blanching
Water Vs Steam Blanching
• Steam blanching has little to no leaching of
nutrients
Blanching
• Blanching prior to freezing
• Blanching of vegetables
prior to canning
– Removes tissue gases
– Cleanses tissue, wilts tissue
• Blanching of fruits before drying
– Surface pasteurization to extend shelf life
– Drying conditions may not destroy enzymes
Blanching
• Losses mainly due to: leaching, thermal
destruction, oxidation
• Amount of losses depend on:
– Type of food
– Extent of particle size reduction
– Ratio of surface area to volume
– Time / temp
– Heating and cooling medium
• Leaching greater in water than steam or air
– Ratio water to food
Pasteurization
• A heat treatment which kills part of the
microbial population present in a food
– Min changes in sensory or nutritive value
• Pasteurization of milk
– Primary objective is to kill pathogenic microorganisms; shelf life is extended due to a
reduction in spoilage organisms, deteriorative
enzymes
– Target pathogens: was Mycobacterium
tuberculosis (TB), now Coxiella burnetti (Q fever)
Mycobacterium tuberculosis
• Are found in infected cattle worldwide.
• These organisms are destroyed by
pasteurization.
• Cause tuberculosis, a lung disease.
• Tuberculosis in the US is not very common
today, although historically milk was a
common source of tuberculosis.
Coxiella burnetii
• The prevalence of Coxiella burnetii was
>94% in raw milk samples from the
Northeastern, Midwestern, and Western
regions of the US tested between 2001
and 2003
Pasteurization
• Two equivalent processes in terms of
microbial kill
• LTH (low temp, hold) = 63°C for 30 min
• HTST (hi temp, short time or flash) = 72°C for 15 sec
• However, LTH is more detrimental to
nutritional and sensory properties
• Don’t drink raw milk – Other pathogens - Ontario study (1997) Listeria
monocytogenes, salmonella, Verotoxogenic E. coli.
Pasteurization
• Beer
– Intention to kill spoilage organismsprimarily wild yeasts, gives a shelf life of
6 months for bottled beer vs 1 month for
draft
• Juices
• Eggs - recommended that pasteurized
eggs be used for salad dressings and
sauces to kill salmonella
– Can now do “in shell”
Sterilization
• A heat treatment sufficient to destroy ALL
microorganisms capable of growth under the conditions
of storage
– This is not true sterility as some nonpathogenic spore
forming bacteria may eventually grow under optimum
conditions
• Severity of the process required for safety and shelf
stability is dependent on the acidity of the food product
being canned.
• Low-acid foods (pH > 4.5)
• Acid foods (pH 3.7 to 4.5)
• High-acid foods (pH < 3.7)
Low Acid Foods (pH 4.5)
• Most severe process is needed for low-acid
foods
– Clostridium botulinum will grow and produce
toxin in foods at pH 4.6 or greater
– Spore-forming, obligate anaerobe, ubiquitous
• Canning of low acid foods (pH > 4.5)
– meats, fish, vegetables, mixed entrees,
most soups
– Need to process at 121°C for ~15 min.
– How do we get water to boil at 121°C
rather than 100°C?
High Acid Foods (pH 4.5)
• Fruit jams, fruit cocktail, tomatoes*** and tomato
juice***, peaches, vegetable juice
– Primary target - facultative anaerobes (Bacillus
spp).
– Can use milder process
• do not need to pressure can, can process at 100°C
• Must make sure tomatoes are acidic enough
• Boiling water bath at atmospheric pressure is
sufficient
High Acid Foods
• Apple juice, cider, berries, citric juices,
sour pickles, sauerkraut
– Targets are yeast and molds
– Anaerobic bacteria won’t grow, so can use
a milder process for spores of yeasts and
molds.
• Can “hot fill” containers at ~90°C
• Should also invert to heat the lid, volume
change on cooling will create slight vacuum
Factors Influencing Severity
• Severity of thermal process required to
produce commercial sterility depends on:
– Nature and heat resistance of the microbes
present
– Initial microbial load
– Nature of the food (e.g. pH, chemical composition,
water activity…)
– Conditions of storage
First Order Kinetics
• Most biological inactivation processes (e.g.,
enzyme denaturation, microbial death, spore
deactivation) are a function of both time and
temperature
• Effect of Time: usually follows first-order
kinetics:
Thermal Resistance
• Death rate of microorganisms is logarithmic
• In a given time interval, at a constant
temperature, the same proportion of a
microbial population will be destroyed
Pasteurization:
• 7 log kill for Salmonella in Milk = 99.99999%
Temperature:
145°F (63C)
161°F (72C)
212°F (100C)
280°F (131C)
Time:
30 min
15 sec
0.01sec
6 sec
• Pasteurization of eggs:
3 log reduction = 99.9%
145°F for 3 to 4 mins.
• Fruit juices are pasteurized to reduce microbial
count and inactivate enzymes; they were thought
not to carry pathogens.
Log Numbers
Time (min)
1
2
3
4
5
6
7
8
9
10
# survivors
1,000,000
100,000
10,000
1,000
100
10
1
0.1
0.01
0.001
Log # survivors
6
5
4
3
2
1
0
-1
-2
-3
Log vs linear
Why Do We Use HTST vs LTLT
Processing
Mild vs. Severe Heat Treatment:
Mild Heat Treatment):
Severe Heat Treatment:
•Aims:
•Kill pathogens
•Reduces bacterial load (Food
is not sterile)
•Inactivate enzymes
•Advantages:
•Minimal damage to flavor,
texture, and nutritional quality.
•Disadvantages:
•Short shelf life
•Another preservation method
must be used, such as
refrigeration or freezing
•Examples:
•Pasteurization
•Blanching
•Aims:
•Kills all bacteria
•Food will be commercially
sterile
•Advantages:
•Long shelf life
•No other preservation method
is necessary
•Disadvantages:
•Food is over-cooked
•Major changes in texture,
flavor, and quality
•Examples:
•Canning
Unit Operations
• Almost all unit operations reduce quality
– Milling
– Evaporation
– Cooking
– Pasteurization
– Irradiation
• However we see benefits
– Convenience, supply and demand, microbial
safety,
Food for Thought
Western countries single largest cause of
morbidity and mortality are diet-related
chronic diseases!!!!
Food for Thought
50-65% of the western adult population are
afflicted with a diet related disease.
Food for Thought
Food related disease do not steam from a single
element of food consumption, but rather from
a complex interaction of multiple nutritional
factors.
Evolution