Food processing Flashcards
what are some of the goals of food processing in the food industry today?
Extend shelf life: inhibit microbial activity
Enhance eating and sensory quality
Change form of food
Enhance nutritional quality
Income generation
Innovative ways to produce consumer desired foods e.g. vegan foods
what are the 3 food processing classifications
- Minimally processed (fruit)
- Processed (canning/pasteurisation)
- Ultra-processed (cake)
what is the purpose of sanitary and phytosanitary measures in the food industry
Safeguards heath of animals, plants and people
what is codex allimentarius
code relating to food and nutrition
Enables harmonization of standards
Facilitate world trade
Assist developing countries
Improve safety of global food supply
what is a trained panel in sensory evaluation
Undergone discriminatory and descriptive tests
Measure type and extent of differences
Achieve objective results
list some different tests used in food sensory evaluation
Forced choice (must pick an answer)
Duo trio test: 1 reference product, 2 different. Select similar to reference.
Descriptive analysis: complete sensory profile with trained panellists. High reliability and precision.
Threshold testing: investigates individuals sensitivity/threshold
Affective testing: indicate preference by selecting/ranking
Paired comparison: 2 diff samples, which one has the most sensory quality
what is the purpose of heat treating food
Increase safety – kill pathogen microorganisms
Extend shelf life, reduce spoilage
Transform raw food –> palatable
Inactivates enzymes (prevent aesthetic changes)
what are 3 factors affecting heat transfer
Composition of product
Thickness and area
temperature
what is HSTS heating
UHT milk
Ultra high temperature
Ultra heat treatment
Not less than 132˚ 3 – 5 sec
what is commercial sterilisation
Objective to destroy all viable microbial cells, spores and enzymes for safety and shelf life
Not for complete sterility
High temperature long time
Shelf life >6 months room temp
Ultra high temperature aseptic processes: heated to 120 – 150 for a few seconds, filled into sterilised container
what are some factors affecting sterilisation time length
Microorganisms heat resistance
Microbial numbers/concentration
Heating conditions
pH (low pH = higher heat)
size and shape of container
physical state of food
what is pasting in starch gelatinisation
amylose leeched into dispersed phase (due to lower molecular weight)
granules gradually loose integrity
disruption of granule
forms paste
possible formation of gel when cooled
what are 5 different ways we can modify starch
bleaching/oxidation
acid hydrolysis
enzyme hydrolysis
substitution
cross linking
what is acid hydrolysis in starch modification
starch chain length reduced due to partial hydrolysis
reduced paste viscosity during cooking
rigid gels form when cool
increased gel strength and clarity
what is substitution in starch modification
hydrogen atoms on hydroxyl groups replaced by substitute groups
prevents re-alignment of linear starch molecules – forms a blocking group
lowers retrogradation and syneresis
–> starch esters
–>starch ethers
what is bleaching in starch modification
oxidise hydroxyl groups to COOH and carbonyl groups
reduce microbial counts
whiten starch
good film forming and binding properties
what is cross linking in starch modification
2 starch chains covalently bonded to a larger one
Increases stability and granule integrity
Minimises rupture during cooking process
High viscosity
what is the purpose of non-thermal food processing
Preserves nutrients
E.g. freezing
o Slows enzymatic activity
o Prevents microbial growth
o Reactants immobilisation
o Reduce chemical reactions
what are the 3 major freezing processes
primary nucleation
secondary nucleation
crystal growth
what is primary nucleation process in freezing
Homogenous: chance, orientation, a combination of water molecules at supersaturation level occurs without presence of a foreign phase
Heterogenous: formation of the nucleus around suspended particles or at a cell wall
what is secondary nucleation process in freezing
crystal growth introduced with contact with other existing crystals – ‘seeds’
what is crystal growth process in freezing
Continuous attachment of water molecules in the seed
Small uniform ice crystals desirable
what are some negative effects of freezing on food
Damaged cells from dehydration
Minimal pigment and flavour change
Can destabilise food emulsions
Can cause proteins to precipitate
Starch retrogradation if slow freezing
what is recrystallisation in freezing
Physical change to ice crystals after freezing
Migratory recrystallisation:
o Increase size of crystals
o Decrease number of crystals
o Due to ‘heat shock’ (constant high and low heat exposure)
o E.g. icecream
what is drip loss
the water not reabsorbed during thawing
what is moisture migration
Movement through osmotic mechanism
Difference in water activity
Ice formation inside package
Contributes to drip loss when thawed
Affects nutrients, appearance, texture
what is irradiation
Preserves food by using ionising radiation
Inactivated microorganisms
Damages genetic material in microorganisms
Changes cell membrane structure
Non thermal
Primary: physical effects
Secondary: chemical effects
