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food science vs agri-food industry
- Food science: system taking food from farm gat to consumer plate
- Agri-food industry: primary agriculture and subsequent food products
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Food industry major segments
- Production
- manufacturing
- distribution
- marketing
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Major food industry commodities
- Cereal and bakery products
- meats, fish and poultry
- dairy
- fruits and veggies
- sugars and confectionery
- fats and oils
- beverages
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allied industries
do not sell food directly but are involved in the industry. Ex. packaging, colouring and flavoring, chemicals, machinery, regulating agencies.
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2 overall perspectives of the food industry
- 1) Customers have 2 things: time and money. try and take as much money!
- 2) Food is a necessity: it should not be a merchandise.
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History of Food Industry/major processes
- Thermal processing (Nicholas Appert)
- Pasteurisation (Louis Pasteur)
- Canning
- Refrigeration
- Frozen foods
- Nutrient Identification
- Freeze drying
- Computer controled processing
- Plastic containers
- Re-engineering of proteins
- Plant sanitation/automation
- Energy efficiency
- RTE Frozen Entrees
- aseptic packaging
- microwave ovens
- Increased nutrition health, convenience and food safety concerns
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Why do we eat?
- Nutrients
- social aspect of food
- consumer trends
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Food Habits
- The way in which we use food:
- Belonging
- status
- security
- self-actualization
- self-definition
- celebrations
- symbols
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Why do societal demands of food industry change?
- Affluence allows for questioning and consumer control
- Greater awareness of self health
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Chemical constitution of food
- Charbohydrates (& sugar free sweetners)
- Protein
- Fat
- Water
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Proximate composition of food (5 major categories)
- Provides info to help processing, storage/shelf-life, energy values, and confoms to legal definitions/identities of foods
- Fat
- Carbs
- Protein
- Water
- Minerals/Ash
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Methods of Proximate analysis
- Kjeldahl (sulphuric acid digestion, protein)
- Soxhlet (solvent extraction, lipids)
- vacuum oven (drying, water)
- Muffle furnace (wight of ash, minerals)
- Leftovers = Carbs
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Kcal/g for macronutrients
- carbs=4
- protein=4
- fat=9
- alcohol=7
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Carbohydrates
- form a ring, then chains
- mono and disaccharides=simple sugars (glucose, fructose, ect)
- oligosaccharides
- polysaccharides=complex carbs
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Sugars pourpose
Sweetness
Humectant/hygroscopic: ability to hold water & therefore preserve.
food for yeast
- Give structure
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- Chemical reactions (carmelisation & Maillard reaction)
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Complex Carbs & pourpose
- Starch (modified starch= stable to heat)
- cellulose (hemi-cellulose, lignin)
- pectin (thickens)
- Pourpose:
- Thicken
- Form gels
- Bind water
- Stabilise proteins
- Prebiotics & probiotics
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Sugar free sweetners
- Aspartame (180x sweeter than sucrose, protein=4Kcal/g)
- Sucralose (Splenda, 600x sweeter, indigestible)
- Stevia (Low cal plant derivative)
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purpose of protein
- colour (maillard reaction)
- Foams
- Thickening
- Texture
- Fat reduction
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Purpose of fats
- add calories
- flavour
- fat soluble vitamins
- texture
- heat transfer
- oxidation (chemical reactions)
- rancidity
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aw
Water activity: dimensionless ratio that describes "free water".
Reduced by addition of salt and sugars (small compounds tie up more moisture)
- aw < 0.60 no microb growth
- aw < 0.90 no microb spoilage
- aw < 0.80 no yeast
- aw < 0.70 no molds
water also effects freezing and heat transfer
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Food acids
- Generally COOH
- adds flavour
- antimicrobial
- low hygroscopicity
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Food composition change during processing?
Only Vitamins and minerals are generally affected by processing
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Food forification
supplementation to provide additions or to restore lost nutrients
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microbes in food
Bacteria, yeast, and mold
- food fermentation
- food spoilage
- food borne illness
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factors affecting microb growth
- nutrients
- water acctivity
- acidity
- oxygen
- temperature
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durable life
the period (starting on the day of packaging) that the food will retain its normal wholesomeness
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Foodborne illness
- Food intoxications: bacterial toxin in food
- Food infections: high number of pathogens ingested
- Toxin-mediated infection: pathogen from food produces toxin once ingested
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danger zone!
anything lower than 60 degrees and higher than 4 degrees should only be allowed for 2 hours.
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GMP
Good Manufacturing Practices
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SOP
Standard Operating Procedures
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Three major preservation processes
- Drying
- Freezing
- Thermal processing (canning)
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Processing
converting/handling commodities into edible food products
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preservation
- ensuring safety and extending shelf life through prevention of decay, spoilage and contamination
- goals: min spoilage, max safety, maintain nutrition
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Unit operation in food processing
- Materials handling
- separating
- cleaning
- disintegrating
- pumping
- mixing
- heat exhange
- evaporation
- drying
- forming
- packaging
- non-thermal methods
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value-added
food which value has been added through special growing, processing or packaging
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categories of manufactured foods
- Primary: basic modification
- Secondary: combination of ingredients to form new foods
- Tertiary: complete food items
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types of spoilage
- microbial
- chemical
- physical
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types of drying
- sun drying (radiant heat)
- hot air drying (enclosed environment)
- spray drying (fluids sprayed into hot air)
- fluidised bed drying (conveyor belt hot air)
- Vacuum drying (decreased pressure = lower temp needed)
- freeze drying (frozen food in a vacuum sublimes water out of food)
- roller drum drying (past type food applied to heated drum)
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slow freezing
creates large ice crystals-> damages cells-> "juices" released at thawing->loss of....-> poor quality.
freezer burn is a result of dehydration
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freezing point of foods
- freezing points are depressed by dissolved substances
- meat=-1.5
- vegies=-1.0
- milk=-0.5
- ice cream=-6.0
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freezing techniques
- increase surface area and speed of freezing
- Sharp freezing- air blasting
- contact plate- scraped surface
- liquid immersion- cryogenic feezing
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factors in thermal processing
- microbial heat resistance
- heat transfer ability of food
- type and size of container
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D values
Decimal reduction time: used to describe heat resistance of microbs and represents the time to destroy 1 log cycle (90%) of bacteria.
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how much heat?
depends on type and number of organisms
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12D
defines a commercially sterile product (probability that one in 10^12 can would have a botulinum spore).
12 log cycle reductions
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Acid foods
pH of 4.6 or less
bacteria are easier to destroy with heat when in acid conditions (lower temp and time neded)
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Types of preservatives
- acid
- sugar and salt
- smoke
- chemicals
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acidulants
food acids which control pH, combined with other techniques for preservation
- acetic: flavour, decreases pH
- benzoic: antimicrobial
- phosphoric: flavour/tartness in beverages
- propionic: antimicrobial
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Radiant heat
- Microwave heating: exciting of h2o
- Irradiation: limited for specific uses
- Ohmic heating (OH): electric current heats at rapid rate, food needs water and electrolytes
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Hurdle Technology
innovative non-thermal meathod combination of low level preservation. ex. aw, pH, temp, and antimicrobial all done together.
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