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1

Stats of food waste/loss

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

2

Resources loss during Agriculture and food waste/loss

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

3

Country taking measures to reduce food waste

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

4

Common saying during WW1 about food scarcity

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

5

4 components of Food spoilage

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)

6

Biological change in food and how to avoid

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

7

Chemical change in food spoilage

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

8

Physical change in food spoilage

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

9

General methods of Food preservation

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

10

Preservation: Drying

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)

11

Conventional drying methods: Drying room

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

12

Conventional drying methods: Tunnel drying

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

13

Conventional drying methods: Spray drying

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

14

Conventional drying methods: Drum drying

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

15

Vacuum drying

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

16

Freeze-drying

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

17

Preservation - Curing

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)

18

Pickling

By Adding acid or fermentation (creates acid) = preservation
Salt is also used to dry out vegetables and prevent microbial growth

19

Edible coating

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)

20

Canning: 2-step process

1790's.
Food sterilized containers and sealed. Containers are heated to destroy microorganisms

21

Canning: Methods

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

22

Heat preservation methods

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

23

Refrigeration

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

24

Freezing (general)

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)

25

Freezing: Ice crystal problem

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

26

Freezing: Freezer burn problem

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

27

Freezing: Oxidation

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)

28

Freezing: Changes in colloidal substances

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

29

Freezing: Development of off-odors

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 :(

30

Irradiation

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.