PKG 455 Exam 3
a very useful tool for finding out when a product comes to equilibrium with its environment
a moisture sorption isotherm
what are some estimation techniques for shelf life?
accelerated storage in lab setting, finding real time results by placing package in abusive condition
what is an indirect food additive?
any material which may reasonably be expected to become an integral component of a food product, which is not a naturally occurring compound in that food stuff as a result of the intended use
what is a food additive?
any substance which results in or may be expected to result in its becoming a component of or otherwise affecting the characteristic of food
a limited amount of O2 is always needed to...
avoid anaerobic conditions and maintain red color of meats
what is apio's temperature responsive package called?
breatheway
how does water affect lipid oxidation?
by influencing the concentration of initiating radicals, the degree of contact and the mobility of reactants
flavor scalping typically occurs in the presence of (3)
carbohydrates oils temperature increase
migration class consisting of dry, hard foods and some frozen foods
class i
migration class consisting of finite level of diffusion and a constant rate, independent of time and food
class ii
migration class consisting of food / packaging material interact, thus disturbing physical structure. diffusion coefficient increase over time
class iii
what is the role of the food and drug administration?
classifying packages as toxic or carcinogenic if necessary
when a food product is placed in an environment at a constant temperature and relative humidity it will eventually...
come to equilibrium with that environment moisture content at steady state
how do packaging materials deteriorate when exposed to sorption?
crazing (network of fine cracks) stress cracks material bond failure
what is cmc?
critical moisture content
what provision defined food additives?
delaney clause 1958 also known as the food additives amendment
permeation coefficient =
diffusion coefficient x solubility coefficient
what is the main concern of migration?
does ingestion pose a health hazard to general public
water activity =
equilibrium relative humidity / 100
what are some methods for determining shelf life?
field studies lab studies based on real time data estimation techniques
interaction of a product or components of a product with the contacting packaging material
flavor scalping / sorption
what provision allowed FDA to oversee the safety of food?
food, drug and cosmetic act
what are the units for moisture content?
g of H2O / 100g of product
what are the two types of migration?
global and specific
gas packs typically require _____ which is why the bottom of the tray is usually...
headspace, ribbed
breathable valve MAP application
heat and eat
the barrier for CAP must be...
high
how does the delaney clause deem food unsafe?
if it is found to induce cancer when ingested by man or animal
how can we solve microbial growth in red meats?
increasing CO2 levels
how can we maintain red color in red meats?
increasing nitrogen levels
CO2 effect in CAP / MAP
inhibit growth of microbes
example of CAP
injecting nitrogen into apple package
what are some basic safety questions for migration?
is the packaging material in contact with the food? does the package material contain only approved additives in permitted concentrations?
what company had a major recall incident as a result of elevated hydrocarbon levels?
kellogg's
why are estimation techniques not as widely used as they could be? (3)
lack of data ignorance in methodology required skepticism of advantages
what is the result of sorption?
loss of flavor in product packaging material can deteriorate
nitrogen effect in CAP / MAP
make-up (makes shit look pretty)
CL = (units)
(P x 1) / (L x A x dP x T) where P = PKG PERMEABILITY L = MATERIAL THICKNESS A = PACKAGE AREA dP = PRESSURE DIFFERENTIAL T = SHELF LIFE TIME CL (CC) = PPM O2 X WT OF PRODUCT X 700CC/G
equation for wet basis moisture content?
(initial weight - final weight)/initial weight x 100
O2 effect in CAP / MAP (3)
- reduction of oxygen reduces respiration - prevents lipid oxidation in high fat foods - reduces aerobic microbial growth
what is the procedure for estimating shelf life? (7)
- select key deteriorative reactions which will cause quality loss - select range of packaging materials and gas compositions - select extrinsic factors to elevate - determine test frequency - calculate sample numbers - plot the data - estimate shelf life
if we're calculating shelf life of a product based on moisture what must we assume? (4)
- shelf life depends solely on moisture content - mc of product will come to equilibrium w/ RH in package - the rh inside of the package is effected by permeability - can be represented by an equilibrium moisture isotherm
what are some estimation techniques for oxygen and preservation shelf life?
- simple absorption models - complex models (finite number and finite element method)
steps of vacuum packaging
- thermoform a barrier material into a cavity - load meat into cavity - heat softened film around product - vacuum seal similar material
examples of active packaging and sensors
- O2 / CO2 scavengers - antimicrobial agents (hexanal) - desiccants - TTI's - ripening indicators
how do we control compatibility problems? (4)
- adding more flavor components to the product - changing the contact packaging layer - modifying characteristics of the material - adding flavor to packaging material
what are the requirements of packaging materials for MAP/CAP (4)
- barrier properties - mechanical properties such as abrasion resistant and tear resistant - clarity (most times) - thermal (sealability)
why are shelf life estimation techniques needed? (4)
- continuous change in distribution systems - trend towards less preservatives - cost increases in energy and materials making under packaging / overpackaging unacceptable - development times are becoming shorter
what are the 3 categories of shelf life testing?
- determining shelf life of existing products - studying the effect of specific factors of package / product combination - determine shelf life of new products
what are the benefits of MAP for fresh produce? (5)
- expanded distribution radius - control of low value products - increased shelf life
what are some methods of gas flushing?
- filling and sealing in a gaseous environment - flushing the package w/ gas - drawing a vacuum
what are some MAP systems?
- films with custom permeability - breathable membranes (patches) - valves - laser and mechanically micro perforated films - specialty films that are responsive to temperature change
direct effects of oxygen on shelf life (4)
- microbial growth - color changes - oxidation of lipids - ripening of fruits and vegetables
what influences product-package interaction? (4)
- physical state - moisture content - polarity - storage conditions
what are the major functions of the shelf life model?
- predict shelf life - select the most suitable package - develop a shelf life cost relationship
benefits of CAP and MAP (8, know some)
- quality maintenance of color, moisture, flavor and maturity retention - favorable economics due to reduction of handling - expanded distribution radius
apples have high sensitivity to
CO2
what is one of the current packaging material migration concerns?
Bisphenol A
what is water activity?
ratio of the vapor pressure exerted by water contained in food to the vapor pressure of pure water at the same temperature
intermediate moisture foods have an aw of
0.5-0.85
high moisture content foods have an aw of
0.85 +
since water activity is temperature dependent, moisture sorption isotherms also exhibit...
temperature dependence
minimum of _____ % CO2 require to inhibit bacterial growth
10-15%
low moisture foods have an aw of
< 0.5
direct effects of moisture on product
texture changes
CAP and MAP
Controlled / Modified Atmosphere Packaging
who authorizes the safety concerns pertaining to product package interaction?
FDA for most foods USDA for a few foods
s =
the addition of water to a dry sample
who is generally responsible for off-flavor development?
the consumer
example of ethylene absorbers
potassium permanganate
for both active and passive MAP permeability must be...
matched to respiration quotient
what types of packaging materials can migrate? (give 5)
material coating lining additives monomers oligomers residual reactants breakdown products closure materials heat sealing adhesives and solvents printing inks
indirect effects of moisture on product
microbial growth flavor loss color change loss of nutrition
packaging material degrading from package and going into product
migration (desoprtion)
what would the composition of a bag of chips be?
moisture barrier n2 flushed to prevent lipid oxidation metallized PP to prevent photo oxidation
field studies consist of..
monitoring sales
what are some product categories for CAP / MAP uses?
muscle foods (fresh / processed) cheese bakery salty snacks pre-cooked pasta coffee produce (respiring products) cook chill
can you use the same correlation factor across different products and packages?
no
example of microperforated package
pepper clam shell
movement of compounds (gases, vapors or liquids) across a homogeneous packaging material
permeation
how can we solve lipid oxidation in red meats?
reducing oxygen
excessive CO2 levels can cause...
reduction in ph flavor tainting drip loss
what is gas flushing?
refers to flushing a product with (n2, o2, co2, argon, etc.) to generate some sort of benefit from it
what is vacuum packaging?
refers to the removal of ambient air from a package made from materials w/ low oxygen permeability by applying a vacuum and then sealing the package
what is specific migration?
refers to the transfer of one or more identifiable substances (i.e. monomer) that is a constituent of the packaging material
what are the results of migration?
safety issues
what is the most important package requirement for MAP / CAP
sealability
the barrier for MAP must be...
selected
how does MAP extend shelf life?
slows ripening slow microbial growth reduces moisture loss
what are sorbates?
sorbates refer to what is diffuses / evaporated from the product and placed onto the package
what is CAP?
storage method where gaseous concentrations, T and RH in a sealed package are modified from those of the ambient atmosphere and maintained throughout storage
anaerobic respiration =
substrate + CO2 ---> acids, alcohols, aldehydes, ketones
aerobic respiration =
substrate + O2 ---> CO2 + H2O
what is active MAP?
technology where ambient air in a package is replaced with a mixture of gases, normally nitrogen, in certain initial proportions and the package is sealed in this mix, and the gas composition then evolves over time depending on the nature of the product, package characteristics and storage conditions
what is passive MAP?
technology where the package is sealed in ambient air and the gas composition then evolves over time depending on the nature of the product, the package characteristics and storage conditions
what are the system parameters for MAP of produce?
temperature time packaging characteristics
what is free water?
water whose properties such as vapor pressure are equal to those of pure water
the end of a product shelf life is reached when..
the moisture content of the food product at time t equals the critical moisture content
d =
the removal of water from a wet sample
what are gas packs?
thermoformed trays that have certain gas compositions to maintain red color and inhibit microbial growth
what is de minimus
too much antimicrobial packaging resulting in the product becoming inedible
what is global migration?
total transfer or the quantity of all substances migrating from the package into the contained food
examples of vacuum packs
trays pouches
(t / f) active pumps gas in, passive pumps clean air in
true
(true or false) water activity is an intrinsic property of the food while equilibrium relative humidity is a property of the atmosphere in equilibrium with the foo
true
what is simulation modeling?
using lab data and mathematical data to estimate shelf life
the moisture content of a food is typically expressed on a ....
wet basis
what is bound water?
when product moisture content is lowered substantially below 50% and the water begins to decrease its activity or availabilty
