Lecture 3: Thermal Processing Flashcards
what did Nicolas Appert invent?
canning or appertisation
what did louis pasteur establish?
microbiologcal basis for food spoilage
what four scientists worked together to discover pH classification of foods?
what was the importance of pH classification?
bigelow, esty, prescott and underwood
importance:
- clostridium botulium only grew in certain pH levels
- established general method for process calculation
what is the ball formula method?
mathematical basis for process calculation
who revised the ball method?
what is this important for?
stumbo
integrated lethality
what did teixeira and manson discover?
computer applications for process calculations and optimization
who discovered retorting? what is it?
chevalier-appert
pressure cooking
what happens when you add salt to water?
increases the boiling point. Allows cooking in water to occur at higher temperatures
what is canning
- method of food preservation that renders a food and its container commercially sterile by the application of heat, alone or in combination with pH and/or water activity and/or chemicals
- the hermetically sealed container maintains sterility of food (prevents entry of microorganisms)
only kills pathogens
what is commercial/shelf sterility
rendering the product free of viable microorganisms of public health significance as well as those capable of reproducing the food under normal non-refrigerated conditions of storage and distribution
describe the steps of commercial canning operations
- harvest
- receiving raw product
- soaking and washing
- sorting and grading
- blanching
- peeling and coring
- filling
- exhausting
- sealing
- processing
- cooling
- labeling
- warehousing and packing
What is the exhausting step in canning?
when the lid of the can is heated with steam, which results in the air space of the can to be replaced by steam to create a vacuum
what is blanching?
mild heat treatment given to fruits and veg prior to freezing, drying and canning
what is the primary purpose of blanching in freezing and drying?
what are other purposes of blanching used in canning?
in freezing and drying: enzyme inactivation
in canning:
- expels intercellular gases (protects can integrity, better vacuum and heat transfer)
- softens tissues for more compact packing
- reduces product microbial load
what are examples of oxidative enzymes?
peroxidase catalse polyphenol oxidase lipase lipoxygenase pectin esterase
what oxidative enzyme is used as the index of blanching adequacy?
peroxidase
which oxidative enzyme is very heat resistant and has a wide occurrence?
peroxidase
what are some common blanching mediums?
water
stea
hot gas
microwave
blanching is….
energy intensive
what are examples of efficient steam blanching systems?
- ABO blanchers
- heat - hold - cool approach
- steam heating and recycling
- forced air cooling (fog get humidified)
what are methods of peeling?
- by hand
- high pressure and steam (for tomatoes and potatoes)
- mechanical (knives)
- chemical: lye peeling (using cuastic soda, dip/spray, acid drip)
what is the important of head space in cans?
- allows for expansion of products to occur when heated
- allows for space for mixing (since mixing can’t occur if the can is completely full)
- allows for high vacuum
what are the types of agitation?
- end over end: rotating up and down
- axial: rotating circularly
- shaken: side to side (most efficient)
what is exhausting?
- process of removing headspace from cans
- reduces strain on cans and jars during retorting
- provides O2 free environment vacuum)