Chap2

Question 1

Stats of food waste/loss

Answer 1

1,3 billion tonnes of food wasted/loss (33% of production)
Dairy products, meat, oilseeds and pulses (20% each), cereal seafood(30% and 35%)fruits vegetables, roots tubers (45% each)
75% of 33% so 25% is due to spoilage
>20% of landfills in USA is food

Question 2

Resources loss during Agriculture and food waste/loss

Answer 2

Resources lost: Water, land, energy, labour and capital. Production of methane. #1 cause of deforestery and water extraction.

Question 3

Country taking measures to reduce food waste

Answer 3

Korea: Eliminated food waste by charging people/company for wasting

Question 4

Common saying during WW1 about food scarcity

Answer 4

Waste not, want not. Means if you do not waste anything, you will not lack of anything. You will still have some for later.

Question 5

4 components of Food spoilage

Answer 5

Decomposition: Natural process, all living matter undergoes. Light, heat, oxygen cause loss of nutritive value.
Consumption by other organisms (micro, rodents, flies)
Obvious and detectable (decreased quality, appearance taste texture odour) and food contamination(toxin,chemical,microorganisms(e.coli)
Most perishable foods = high in proteins(meat, seafood) and or water(fruits, vegetables). Opposite(flour,root vegetables)

Question 6

Biological change in food and how to avoid

Answer 6

Microorganisms: Need nutrients to survive and water. Food provides all of these.
Fungus (mostly yeasts): plant that lacks chlorophyll, ferment sugars (CHO into CO2 and alcohol). Used for bread alcohol.
Bacteria and Molds: can produce toxins(lobster), molds are visible bacteria are not, bacteria can ferment sugars. B prefer meat, eggs,milk
M prefer bread,cheese(especially soft bcuz high in lactose), high sugar food
Boiling, curing (salt,sugar), refrigerating, drying

Question 7

Chemical change in food spoilage

Answer 7

Enzymatic reactions: Substrate + enzyme
Proteins + protease(proteolytic enzyme) = AA
TG + lipase = FA + glycerol
CHO + carbohydrase = glucose
Polyphenol oxidase (ppo) = browning in apples, mangoes, potatoes.
Fish and seafood have a huge amount of proteases that work right away when the fish dies. It gets spoiled really quickly. Freezing and cooling and refrigerating helps.
Non enzymatic reactions:
Oxydation of fat
Maillard reactions: 1. non-fat dry milk(lactose +protein = nonenzymatic browning) 2.BV of protein decreases bcuz AA involved in Maillard reaction are not released during digestion but they should be

Question 8

Physical change in food spoilage

Answer 8

Evaporation/dehydration
Separation: drip loss = drier products (frozen foods)
Emulsion breakdown: reformation of 2 different layers
Syneresis: water in the matrix seeks out
Damage/mechanical bruising, tearing of tissues

Question 9

General methods of Food preservation

Answer 9

High T: Kill microorganisms and enzymes
Low T: Control growth of microorganisms
Removal/tying up the moisture: Control microorganisms growth (no water to develop) by adding salt/sugar or drying.
Chemical preservatives: Inhibit microorganisms growth
Keeping out microorganisms
Ionizing radiations: Destroy microorganisms and control enzyme activity

Question 10

Preservation: Drying

Answer 10

Inhibits growth of microorgaisms (less water to grow)
Bacteria need 15% moisture level to survive
Yeasts need 20% moisture level to survive
Traditional
Commercial: Conventional, vacuum( low pressure), osmotic (use strong syrup of salt/sugar +++), Freeze-drying (ice crystals vaporize)

Question 11

Conventional drying methods: Drying room

Answer 11

Drying room: Good flow of ventilation, hot air. Room is removed from all of the yeasts,bacterias…

Question 12

Conventional drying methods: Tunnel drying

Answer 12

Tunnel: trays on trolleys move through a tunnel where the heat is applied and the vapours removed. In most cases, air is used in tunnel drying

Question 13

Conventional drying methods: Spray drying

Answer 13

Spray: Really hot air. Spraying the food in the air and by the time it gets down, it has time to dry out because the air is extremely hot.
Coffee and dairy industry

Question 14

Conventional drying methods: Drum drying

Answer 14

Drum drying.The principle of the roller drying process is that a thin film of material is applied to the smooth surface of a continuously rotating, steam heated metal drum. The film of the dried material is continuously scraped off by a stationary knife located opposite the point of application of the liquid material.Potato flake, oat flake

Question 15

Vacuum drying

Answer 15

VACUUM:Low moisture also (1-3% moisture level) Food placed in a chamber with low pressure. Low pressure means boiling point of water boils off at a really low T. so not a lot of heat require so no degradation of the food. Tomato paste, orange juice

Question 16

Freeze-drying

Answer 16

Freeze-drying: Really expensive. Taking something from ice to vapors (freezing, low pressure and low and high T). Maintains the integrity. Camping trips,army,some coffees. people going out for a long period of time use it because really good quality. ICE CRYSTALS VAPORIZE

Question 17

Preservation - Curing

Answer 17

Microorganisms can still grow but slower, addition of salt and drying. Sugar, spices, nitrates, smoke also added (provides a seal, outer layer to reduce microbial presence and activity + flavour)

Question 18

Pickling

Answer 18

By Adding acid or fermentation (creates acid) = preservation

Salt is also used to dry out vegetables and prevent microbial growth

Question 19

Edible coating

Answer 19

Can be CHO (some contain seaweed extract)-PRO-Fat
Increases shelf life: barrier to moisture, O2m reduces respiration rate
Improves handling: less breaking/damage
Improves appearance: increasing gloss
Vehicule for added ingredients (antioxydants, antimicrobial)

Question 20

Canning: 2-step process

Answer 20

1790’s.

Food sterilized containers and sealed. Containers are heated to destroy microorganisms

Question 21

Canning: Methods

Answer 21

Boiling water and putting the jar in the water. Good for acidic items (ph=4,5 or below).Heat resistance in microbes in acidic environment is decreased, Surviving organism will not grow in a low acidic environment
Pressure canning: Good for basic items (ph=4,5 or more), higher temperature with pressure canner. Destroy Clostridium botulinum

Question 22

Heat preservation methods

Answer 22

Boiling: 10minutes, used for anything
Pasteurization: Liquids heated to a certain T for a certain time. (e.g: 71C 15sec 138C 2sec(no big nutrient loss) kills bacteria molds and yeasts
Ohmic heating: Electrical current passed through food = generates heat that kills microorganisms, liquid eggs, fruit juices

Question 23

Refrigeration

Answer 23

Refrigiration: Slows down biological,chemical physical reactions. High water content foods benefit most. T is = or just above 4C. Refrigerate asap (during transport).

Question 24

Freezing (general)

Answer 24

Freezing: -18C or lower = least damaging to flavor. Water unavailable to microorganisms. Slows chemical and physical reactions. Problems: fluid loss, freezer burn, recrystallization, cell rupturing, reaction continues(O2 present)

Question 25

Freezing: Ice crystal problem

Answer 25

Formation and growth of ice crystals:
Rapidly frozen: small and numerous, intracellular, better food
Slowly: large and fewer, extracellular spaces, sharp, perform cells

Question 26

Freezing: Freezer burn problem

Answer 26

Freezer burn: dehydration on the surface of frozen foods caused by inadequate packaging (water evaporates and may recrystallize on the surface)

Question 27

Freezing: Oxidation

Answer 27

Oxidation of fat
Oxidation of Vit C
Blanching inhibits it by inacivating ascorbate oxidase
Some loss during blanching + some other vit c losses during freezing
Oxidation of polyphenolic substances by polyphenolases may occur during freezing = Browning.
To prevent: blanching destroys enzymes(ppo)

Question 28

Freezing: Changes in colloidal substances

Answer 28

Retrogradation of starch
Syneresis
Toughening of cellulose(e.g.: celery has a lot of cellulose and it hardens)
Breaking of emulsion
No big loss of vit and min (4% loss in drip, mostly water soluble B (folate!) and C

Question 29

Freezing: Development of off-odors

Answer 29

Development of off-odors:
Accumulation or volatile carbonyl in unblanched vegetables
Blanching: destroys enzymes that give off-flavors, controls changes in texture, color(inhibtis conversion of chlorophyll to olive green pheophytin, destroys vit c and folate :(

Question 30

Irradiation

Answer 30

Irridiation: Foods treated with low doses of gamma rays, x rays or electronsIonizing radiations safe for humans. Destroys bacteria, molds and yeasts. Control insects in wheat, flour, and whole wheat flour. Preventing sprouting or germination in potatoes/onions. Foods approved by Health Canada for irradiation: potatoes, onions, wheat, flour, whole wheat flour, whole and ground spices, dehydrated seasoning preparations, fresh and frozen ground beef.

Question 31

Aseptic packaging & MAP

Answer 31

Aseptic packaging: Sterilized and sealed in sterilized container under sterilized conditions. Can sit at room temp: juice boxes, pudding, babyfoods,uht milk
MAP: Modified atmosphere packaging: Composing of air changed: less O2, more CO2, fruits, vegetables, meat,poultry , baked goods.
Hermetically sealed: “Foods that have been packaged airtight by a commercial sealing process.”