Flashcards in Thermal Processing Deck (69)
types of thermal processing?
cooking, blanching, pasteurization, sterilization
most widely applied unit op in food processing?
three basic mechs of heat transfer?
conduction, convection, radiation
conduction is heating of ___, convection is heating of ___
examples of radiation?
infrared, microwave, dielectric
primary objective of cooking?
baking and roasting happen at _____degrees, frying happen at ____ degrees
cooking inactivates ____ factors like ___ in pulses
anti-nutritional factors; lectins
___ bioavailability reduced by ___ browning
lysine; Maillard (non enzymatic)
these vitamins decrease in bioavailability but not concentration with cooking
vitamin A and D
these vits decreases in both [ ] and availability
thiamine, niacin, folate
primary purpose of blanching?
inactivate deteriorative enzymes, kill spoilage bacteria
blanching usually done on __ foods, prior to ____
blanching reduces ___ by removing tissue gases
blanching of fruits before ___ allows surface ___
blanching inactivates these deteriorative enzymes
LOX (lipoxygenase), polyphenol oxidase (PPO), pectinase
pectinase ___ plant tissues
blanching is referred to as :
hot break process
loss of nutrients during blanching is mainly due to;
leaching (loss of ascorbic), thermal destruction, oxidation
what is observed as indicator of severity of blanching?
loss of ascorbic acid
A heat treatment which kills part of the microbial population present in food
target pathogens in pasteurization in milk?
tuberculosis (old), coxiella burnetti (new)
What are the two processes in pasteurization?
LTH is at __ degrees for ___ minutes; HTST is at ___ degrees for ___ seconds
63; 30; 72; 15
Is LTH or HTST more detrimental to nutritional/sensory properties?
2 processes in pasteurization?
batch (small), continuous (large)
equipment used in continuous process?
PHE (plate heat exchanger)-->high production rate, no overheating
why is PHE corrugated?
for more surface area-->more points of contact
foods that are pasteurized?
milk, beer, juices, eggs