Chap2 Flashcards
(31 cards)
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
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.
Country taking measures to reduce food waste
Korea: Eliminated food waste by charging people/company for wasting
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.
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)
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
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
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
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
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)
Conventional drying methods: Drying room
Drying room: Good flow of ventilation, hot air. Room is removed from all of the yeasts,bacterias…
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
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
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
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
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
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)
Pickling
By Adding acid or fermentation (creates acid) = preservation
Salt is also used to dry out vegetables and prevent microbial growth
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)
Canning: 2-step process
1790’s.
Food sterilized containers and sealed. Containers are heated to destroy microorganisms
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
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
Refrigeration
Refrigiration: Slows down biological,chemical physical reactions. High water content foods benefit most. T is = or just above 4C. Refrigerate asap (during transport).
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)
