FOOD PRESERVATION 1 Flashcards
what’s the goal of food preservation
extend shellfire to allow storage and convenient distribution
whats the most dangerous limitation to food preservation
microorganisms
whats the primary aim of food preservation
eliminate microbial spoilage by limiting available water
what are some physical methods of food preservation
concentration, dehydration, freezing
what are some chemical methods of food preservation
addition of solutes (sugars, salts)
what changes contribute to food spoilage
biological, chemical, physic
what are three causes of biological spoilage
bacteria, yeasts, molds
what foods are susceptible to bacteria spoilage + how to prevent?
high water activity + high protein
can control by keeping water activity low
what is yeast attracted to
liquid foods high in sugar (fruits + preserves)
what does yeast caused + how can you prevent
can cause unwanted fermentation + can control by keeping water activity low
what will mold grow on
almost any foods under suitable conditions of moisture, air and temp
how to control mold?
can control by keeping oxygen levels low (vacuum)
describe enzymatic spoilage
chemical changes due to enzymes; proteins that catalyze chemical reactions
describe proteases
spilt proteins into smaller peptide and polypeptide fragments
what do good proteases do
create food flavor and vice versa
what do lipases do
contribute to enzymatic spoilage; break down lipid (triglycerides) into glycerol and fatty acids
what does further enzymatic/lipid degradation lead to
rancidity (off odors/ taste) due to reaction with oxygen or water
what do carbohydrates do
breakdown carbohydrates (typically named after carb they act on)
whats an example of a carbohydrase
amylase
whats polyphenol oxidase
undesirable browning of fruits and vegetables; enzymatic spolage
what is physical spoilage due to
water migration
name two types of physical spoilage
evaporation + seperatiion
describe evaporation
water loss due to improper storage + undesirable dried out appearance
describe seperation
water + oil separation; unlike chemical changes, dont result in formation of new compounds
what is the most important thing to control in food preservation
water
whats drying + name five types
removal of water
sun-drying; conventional; vacuum; osmotic; freeze-drying
what does drying do
inhibits growth of microorganisms
whats sun-drying
sun provides heat to evaporate water (ex: tomatoes)
whats conventional drying
uses heat to evaporate water; tray, tunnel, drum, spray-drying, big oven (ex: whey)
whats vacuum-drying
pressure is lowered below atmospheric, which lowers boiling point of water (ex: tomato paste)
whats osmotic drying
uses concentrated syrup to osmotically draw out water (craisins)
whats freeze-drying
frozen solid water is sublimated (solid to gas) at low pressure and temp (ex: instant coffee)
whats curing
high concentrations of solutes (salts, nitrates, nitrites, sugars, etc) draw water out of food, making it unavailable to microorganisms
describe smoking cured meats
meats exposed to smoke of burning wood for added flavor (flavor depends on type of wood)
whats fermentation
microorganisms convert sugar -> alcohol, gases, acids
describe why fermentation works
most spoilage microorganisms cannot survive in acidic or alcoholic environment
