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277 Cards in this Set
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What is chilling injury? |
a physiological injury that occurs to plant tissues due to their exposure to temperatures above their freezing point, but below 15*C (59*F)
(refers to produce that is sensitive to cool temperatures usually below 55 and above 32*F) |
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What origins of plants are typically sensitive to cool temperatures? |
sub-tropical and tropical origins
tomato, eggplant, bell pepper, cucumber, sweet potato, watermelon, citrus, bananas, avocado
some temperate plants - apples, pears, peaches, cranberries |
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Which temperate crops are cold sensitive? |
apples, pears, peaches, and cranberries |
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What relative temperature do temperate crops chill at? |
much lower temperatures than sub/tropical plants |
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At what temperatures should apples be stored to avoid chilling damage? |
33-35*F
prolonged periods at 32 or lower will cause chill |
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What causes peaches to become mealy, dry, and lose palatability? |
when chilled at 32*F for more than 3-4 weeks |
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T/F: Chilling sensitivity is cultivar specific |
True |
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symptoms of chilling injury |
pitting of the surface (death of underlying cells with resulting collapse)
discoloration of tissues
increased decay
uneven ripening or no ripening at all
increased water loss due to the disruption of epidermis (depends on whether pits form holes or not) |
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T/F: cucumbers decay rapidly in the refrigerator due to natural senescence |
False; cucumbers decay rapidly in refrigerator due to the cold |
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When do chilling injury symptoms typically become visible/noticeable? |
symptoms usually develop after removal to a non-chilling temperature
(can be a problem with transport) |
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T/F: Many times, the effect of chilling at night can be reversed by the warmth of the day if chilling stress is not too severe (when chilling injury occurs in the field before harvest) |
True |
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T/F: ideally all crops should be stored at their freezing point |
False; crops should be stored just above their freezing point |
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Define chilling threshold |
the lowest safe temperature at which a commodity can be stored before cold temperature injury begins |
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With chilling sensitive crops, what is the lowest safe storage temperature limited by? |
chilling threshold |
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How does chilling threshold affect the duration of storage of commodities? |
chilling thresholds limit the amount of time it can be stored (a few weeks instead of a few months) |
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at what temperature is respiration the lowest? |
32*F |
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What does it mean (in terms of respiration) if the chilling threshold of a commodity is 55*F? |
it means that respiration is 2-3 times higher at 55*F than 32*F; causing a the storage time of a commodity to reduce by 2-3 times.
(4-6 weeks storage time at 32 can be reduced to 2 weeks at 55) |
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What are the two factors of chilling injury? |
time and temperature |
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How do time and temperature relate in reference to chilling damage? |
the lower the temperature and the longer the time, the more quickly injury will develop |
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T/F: Small doses of chilling temperature may have no real effect on marketability |
True |
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How can chilling injury potentially be reversed? |
by periods of non-chilling temperatures
i.e. a few days at chill temperature followed by a day at non-chilling temperature will reverse effects and the product will be okay |
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What will happen to the storability of products when subjected to extensive chilling periods before harvest? |
chilling in the field can be cumulative; crops exposed to a lot of cold before harvest may not store well after harvest, even if storage conditions are ideal |
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T/F: Fall harvest tomatoes store better than late summer harvest tomatoes |
FALSE; fall harvests of tomatoes do not store as well as summer harvests due to their potential exposure to cold rainy conditions |
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What is the Lyons-Raison hypothesis? |
proposed idea that the underlying cause of chilling sensitivity is that cell membranes went from liquid crystalline to gel when chilled (injured)
proposed that this can be controlled genetically
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What are the problems with genetically controlling chilling injury as proposed by the Lyons-Raison hypothesis? |
"sow ear to silk purse" syndrome - you cant make a good product with bad material |
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Who discovered respiratory climacteric? When? |
Kidd and West 1925 |
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What is respiratory climacteric? |
defined as a characteristic rise in respiration during ripening
measured as the rise in CO2 production |
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Which is larger, the rise in the rate of respiration as a result of climacteric respiration, or the respiration rate of developing fruit? |
Although there is a dramatic rise in respiration during the climacteric, it is small compared to the respiration rate of developing fruit |
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To what factors of ripening is the climacteric associated with? |
quick ripening during which fruit soften, change color, develop flavor and odor, convert starch to sugar, etc. |
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list of climacteric fruits |
Fruits that can ripen after harvest
muskmelon, tomato, avocado, watermelon, honeydew melon, apple and many deciduous fruits |
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list of non-climacteric fruits |
Fruits that do not ripen after harvested
bell pepper, winter squash, citrus fruit, olive, grapes |
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Where do climacteric fruits ripen? |
off the tree/vine
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where do non-climacteric fruits ripen |
on the tree/vine |
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What controls ripening? |
ripening is an enzymatically-controlled sequence of events |
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What regulates ripening? |
Ripening is hormonally regulated |
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What kind of energy does ripening require? |
ripening requires respiratory energy |
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What changes are attributed to ripening? |
softening, pigment changes, changes in oils, fats, and waxes; changes in carbohydrate content, changes in flavor |
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what is the primary enzyme involved in fruit softening? |
polygalacturonase (PG) |
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what is the function of polygalacturanase (PG)? |
it is an enzyme primarily responsible for the softening of fruit
PG attacks polygalacturonic acid, a major component of the middle lamella pectin |
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What pigment changes occur in tomatoes as they ripen? |
due to pigment formation and chlorophyll degradation, chlorophyll is converted to lycopene |
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why do changes occur in pigments causing browning in bananas? |
ripening; chlorophyll disappears without an increase of pigment |
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usually, what do pigment changes involve in regards to ripening? |
usually ripening changes involve chlorophyll decrease and pigment increase
exception is bananas |
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What are the two major classes of pigments involved in fruits, vegetables, and flowers? |
flavonoids and carotenoids |
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what are Flavonoids? |
pigments involved in fruits vegetables and flowers that are responsible for red and blue coloration |
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what are Carotenoids? |
fat soluble pigments that include chlorophyll and lycopene
they are responsible for yellow, gold, red, and orange coloration in pumpkin, squash, melon, flesh, and most vegetables |
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what are anthocyanins? |
pigments found in vacuoles that are responsible for the blue and red of fruits and veggies
(yellow in flowers) |
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T/F: cooked items containing carotenoids change color |
False; cooked items containing cartoenoids do not normally change color as pH has little effect |
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What physical state are fats in at room temperature? |
solid at room temperature; usually unsaturated (contain no double bonds; they are hydrocarbons) |
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What physical state are oils in at room temperature? |
oils are liquid at room temperature and are unsaturated
(they contain some double bonds; the more double bonds (the more unsaturated) the higher the burning/boiling point) |
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What are waxes? |
complex hydrocarbons and are most important with plants in limiting water loss from tissue surfaces |
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T/F: changes in oils, fats, and waxes due to ripening is not of extreme importance in most fruits, flowers, and vegetables |
True; the exceptions are nuts, avocados and olives for olive oil production |
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What commodities are considered when talking about the changes in oils, fats and waxes due to ripening? |
avocados - up to 25% oil
nuts are often high in oil; pecan may contain 74%
important in olive oil production |
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What happens to sugars as fruits ripen |
sugar content of most fruits increase with ripening |
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What are the two main types of sugars in fruits and vegetables? |
fructose/levulose (reducing sugars)
Sucrose (molecule comprised of joined fructose and glucose) |
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What are the reducing sugars? |
sugars that are reduced during ripening
fructose/levulose; glucose/dextrose |
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what is Sucrose? |
a sugar molecule comprised of joined fructose and glucose |
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What does sugar accumulation correlate with in starch containing fruits? |
in fruits containing starch, sugar accumulation correlates with starch degradation
(bananas, apples, many tree fruits, sweet corn) |
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When is starch conversion to sugar undesirable? |
in irish potatoes; when they are stored at too cold of a temperature |
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what are sugars measured as? |
soluble solids |
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Why does the pattern of sugars increase and decrease? |
maturity line depends upon use
exact pattern by species, variety, and conditions
grapefruit only lose sugar after harvest
rate of decrease is very temperature dependent through the effect of respiration |
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T/F: The rate of decrease in sugars is temperature dependent through the effect of respiration |
TRUE; the rate of decrease is VERY temperature dependent through the effect of respiration |
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As fruits ripen, changes in flavor occur. What factors change, causing flavor differences to our tastebuds? |
flavor is comprised of changes in sweetness and sourness combined with changes in the volatile production of fruits and vegetables
we taste with our nose and our tongue |
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What causes sourness? |
due primarily to the accumulation of organic acid in cells derived from the krebs cycle (citric acid cycle), primarily and some associated pathways |
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main types of acids |
malic, citric, tannic, tartaric, acetic, oxalic |
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What fruits are comprised mostly of malic acids? |
melons and apples |
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what fruits are comprised mostly of citric acids? |
citrus, melons
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What is most effected by the presence of tannic acids? |
bitterness in wines from stems and seeds; the "tannins" |
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what fruits are mostly made up of tartaric acids? |
grapes |
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Where is acetic acid most commonly found? |
vinegar |
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what fruits are associated with oxalic acid |
monstera fruit |
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what happens to acid content as fruits ripen? |
acid content declines as fruits ripen |
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What affects the rate of loss (of acids) in fruits |
temperature; the greater losses generally occur at higher temperatures |
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T/F: Fruits can lose acid at freezing temperatures |
True |
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What is the Maillard reaction? |
Amino acids + Sugars (yield) heat (yield) pigments |
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What is the difference between curing and conditioning? |
Curing is the healing of cuts and abraisions
Conditioning = warmer temperatures raise respiration rate and burn off sugars (potatoes) resulting in changes in physical characteristics such as the chippability and the blonde frying of sweet potatoes. |
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what does soluble solids refer to |
everything that is dissolved in the cytoplasm of the cell; the largest proportion is usually sugars |
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Define Refraction |
change in angle of light from one medium to the next; the bending of light as it passes through a solution |
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Define brix |
the amount of refraction changes as sugar content increases (more sugar = more bend in light) |
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What does a refractometer measure in lemons? |
Citric acid; because lemons have essentially no sugar, the refractometer readings indicate the amount of organic acids in the fruit, not the sugar content |
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How many volatiles has research proven apples to have, making up its aroma? |
research has indicated that some apple varieties have over 159 volatiles that make up the apple aroma
20 acids, 28 alcohols, 71 esters, 26 carbonyls, 9 ethers and acetals, 5 hydrocarbons |
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What happens to volatiles over time as fruits ripen? |
in general, volatiles decrease over time as fruits have ripened and as tissues senesce |
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When do volatiles decrease most rapidly? |
at high temperatures |
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In climacteric fruit, what does their peak production of volatiles coincide with? |
their peak production coincides with the respiratory peak |
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How can time of harvest affect the volatile production/profile? |
Early harvest can and will reduce/shift volatile production/profile
example: forced breaker tomatoes produce a less complex mixture and a different mixture than tomatoes picked red from the vine |
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What are polyphenols? |
aromic ring with hydroxl
sour/bitter compounds |
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What happens to polyphenols as fruits ripen? |
plant tissues usually do not have much to start out with and the levels decline as ripening proceeds (persimmons still have considerable amounts at the time of eating) |
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How are polyphenols related to the browning of flesh? |
phenols plus polyphonoloxidase produce quinones which are then changed to melanin (browning pigments; typically found in apples, artichokes, etc.) |
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what enzymes are released when fruits are damaged? |
phenolases; aka: polyphenol oxidase (PPO), tyrosinase, cresolase, catecholase |
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what is a co-factor of PPO? |
copper |
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what are the phenolic substrates for the reaction of PPO to produce melanin? |
tyrosine (amino acid), caffeic acid, chlorogenic acid (primary substrate in apples) and protocatechuic acid |
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in what products is enzymatic browning desireable? |
black tea, cocoa, and cider |
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what is the method of controlling browning? |
inactivating phenolases, chelating copper, or excluding oxygen. |
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what are 3 methods of inhibiting PPO in order to control browning |
blanching to inactivate the enzyme
storage under vacuum or immersion in salt brine, sugar syrup, or even water may be used to inhibit enzymatic browning by excluding oxygen
chemical agents |
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What are the methods of blanching to inactivate enzymes? |
short term exposure to steam or heat
lime in guacomole
parsley added to basil pesto to keep it green because parsley doesn't brown
adding a layer of oil on top of the pesto to exclude oxygen |
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how do chemical agents inactivate PPO? |
directly inactivate the enzyme
reduction of pH to inactivate enzyme
chelation of copper |
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What are some commonly used antibrowning agents that are used to limit the reaction of the PPO enzyme? |
citric acid
sulfur dioxide and sulfite salts
ascorbic acid
L-Cystein
calcium ascorbate |
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What are the properties of Citric acid that contribute to its antibrowning capability? |
inactivate phenolases by acting as acidulants to reduce pH
citric acid chelates copper |
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in what forms can citric acid be used? |
Pure
as its calcium, potassium, or sodium salts |
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what is the desirable pH to inactivate PPO? |
pH must be reduced and maintained at 3.0 or less to inactivate the enzyme |
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T/F: Citrates are GRAS |
true |
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What is sulfur dioxide and sulfite salts still commonly used for? |
dried fruit and grapes for winemaking |
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why are we trying to get away from using sulfur dioxide and other sulfide salts? |
sulfur sensitivities of some people |
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How does sulfur dioxide/sulfites affect PPO enzyme? |
causes irreversible inactivation of phenolases
also antimicrobial |
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what is the primary component of sulfur dioxide and sulfites which inactivates PPO? |
the bisulfite ion (HSO3-) |
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why are sulfites commonly added to certain dehydrated fruits and vegetables? |
to inhibit non-enzymatic browning during storage due to the condensation of phenolic compounds, oxidation of ascorbic acid, carmelization, and maillard-type reactions |
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T/F: sulfur is antimicrobial |
True |
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Why are sulfites prohibited on fresh fruits and vegetables? |
sensitivity in some individuals to bisulfites |
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How do sulfur chemicals react with vitamin B1? |
they degrade thiamine (vitamin B1) so they are not allowed in foods considered to be important sources of the vitamin in the human diet |
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at what rate are sulfur dioxide and sulfite salts used in processed foods? |
up to 200 ppm
at these high levels, flavor and odor may be noticeably affected |
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In what forms can Ascorbic Acid be found |
pure as calcium and sodium salts |
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In what ways does ascorbic acid (ascorbates) aid in the reduction of enzymatic browning? |
acts as a reducing agent by transferring hydrogen atoms back to quinones to produce dihydroxyphenylalanine (DOPA)
oxygen scavenger, removing oxygen from solution
synergists with other antioxidants by acting as metal chelators |
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How can ascorbic acid be used to control enzymatic browning? |
ascorbic acid plus citric acid in gas-impermeable plastic film controls enzymatic browning during storage of fresh commodities |
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T/F: Ascorbic acid is FDA approved as GRAS |
True
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T/F: Sulfur dioxide and sulfite salts are approved by FDA as GRAS |
false |
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What is L-cysteine? |
another amino acid containing sulfur that is reported to be more effective than sodium bisulfate as an antibrowning agent |
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T/F: L-cysteine is more effective than sodium bisulfate as an antibrowning agent |
True |
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What negative effect does effective levels of L-cysteine as an antibrowning agent have? |
may also negatively affect taste |
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What makes L-cysteine effective as an anti-browning agent? |
it is a reducing agent |
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What is natureseal? |
a patented product comprised mostly of calcium ascorbate to prevent browning
expensive |
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How is calcium ascorbate (natureseal) used? |
very effective in preventing browning on some commodites such as precut apples
up to 21 days if used as a 10% dip before packaging
commonly used in industry as a 5-10% range to save money |
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T/F: calcium ascorbate (natureseal) is an antimicrobial |
False; it is pH neutral so it does not control the growth of microbes |
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What other compounds are being investigated or tested, but are presently limited or specialized in use? |
Erythorbic acid
sodium acid pyrophosphate
sodium ascorbate
sodium metaphosphate
calcium chloride
carrageenans |
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What are carrageenans? |
derivatives of seaweed which have some efficacy in preventing browning
complex sugars |
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What is the most universally important factor influencing the effectiveness of food antimicrobials? |
pH |
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When are food antimicrobials most effective? |
many food antimicrobials are weak acids and are most effective in their undissociated form therefore the lower the pH, the more effective they tend to be (pH 4 or less) |
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how and what (type of bacteria) does citric acid prevent microbial growth? |
inhibitory toward thermophilic and mesophilic spore-forming bacteria
C. botulinum (types A and B) C. sporogenes L. monocytogenes S. typhimurium P. fluorescens S. aureus Molds: A. parasticus and A. versicolor |
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When is citric acid a good antimicrobial? |
low pH and or high concentrations of the compound |
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When and where were sulfur dioxide treatments used in history? |
ancient rome
used as a treatment for wines |
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T/F: Sulfur dioxide is colorless, flammable, and strong in odor |
False; it is colorless, nonflammable gas with a strong penetrating odor |
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What are the types of sulfur that can be used as antimicrobials? |
sulfur dioxide, sodium sulfite, sodium bisulfite, and sodium metabisulfite
and their potassium salts |
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What is the effectiveness of sulfur as an antimicrobial dependent on? |
pH, concentration, type of microorganism, duration of contact, and binding of compounds |
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What is the active form of sulfur as an antimicrobial? |
undissociated sulfurous acid (sulfur dioxide in water)
most active with a pH less than 4 |
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T/F: bisulfite ion (HSO3-) and Sulfite ion (SO3-2) is effective in microbial control |
false; very ineffective |
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What primary mechanism are sulfites dependent on as antimicrobials? |
the primary mechanism by which the compound inhibits microorganisms involves the inhibition of cellular enzymes |
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What types of microbes are sulfites active against? |
sulfites are active against certain types of bacteria, yeasts, and molds: acetic-acid producing bacteria, maloactic bacteria, fermentation and spoilage yeasts and molds on fruits |
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Against target fungi, the concentration of sulfites are... |
the concentration of sulfites are relatively low for the inhibition of target fungi
max amount in wine is set at 350mg/liter |
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Given the following sulfur compounds, give their specific formulas:
Sulfur dioxide
sodium bisulfite
sodium sulfite
sodium metabisulfite |
SO2
NaHSO3
Na2SO3
Na2S2O3 |
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What needs to be listed on packages? |
grade, size, and weight |
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How many different sized containers for fruits and vegetables are available? |
547 |
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What would the industry do if it were able to standardize containers? |
reduce manufacturing costs (inventory would be reduced)
reduce inventory costs for manufacturer and packer (not as machinery)
result in more efficient use of space in the warehouse, storage and trucks |
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T/F: most shipping containers are getting smaller |
True; 10-15 years ago 60-90 lbs
now: 20-50lbs |
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what are units in terms of packaging? |
described by count, weight, or volume |
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what are the main functions of packages |
provide physical protection
contain a unit or units
facilitate orderly marketing of a commodity
must be adaptable to the packing line as well as to the needs of marketing and retailing
identification
reduce losses from pilferage |
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How do packages protect commodities? |
protect both from physical injury and from contamination and/or infestation with soil, insects, fungi, etc |
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How are packages identified? |
container should have name and address of packer as is par to the Perishable AGricultural Commodity act (PACA) - whatever is on the box better be accurate or you will be sued
What is contained within
other pertinent information |
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How does packaging reduce pilferage? |
harder to steal a bag or box of items |
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What are the 11 package types? |
barrel, bushel baskets, wooden boxes, wire-bound wooden crates, LA lug, bulk pallet boxes or bins, fiberboard box, reusable plastic containers (RPC), burlap sacks, mesh bags, and fiberboard flats holding individual plastic pints, and styrofoam boxes |
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T/F: barrels are a common way of packaging in the united states |
false |
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what is a bushel of tomatoes legally defined as? |
50lbs (weight changes per commodity) |
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What commodities are still packaged in bushel baskets? |
snap beans, southern peas (cow peas), etc.
this is especially true with truck farms, road-side stands |
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major problem with bushel baskets? |
can't stack |
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Characteristics of wooden boxes as packages? |
possesses rigidity (nailed closed)
excellent stacking strength
not commonly used due to the cost of materials. |
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What are the benefits of wire-bound wooden crates? |
5 dozen ears of sweet corn can be stored
good strength and stacking capacity
good ventilation for precooling and transit
adapted to mechanical assembly and closure |
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What is the major disadvantage of wire-bound wooden crates? |
if overfilled, can get a lot of damage |
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What is an LA lug? |
shipping container made of composite or wood sides with fiberboard bottom, front, and back
more current versions have wooden ends and fiberboard bottoms and sides |
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how much weight can an LA lug hold? |
23-25 pounds |
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What commodites are commonly packed in LA lugs? |
stone fruit and grapes |
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Disadvantages of using bulk pallet boxes or bins |
wooden, heavy
need fork lifts to move
wood is porous and therefore needs to be sterilized very well since they can absorb water and harbor disease spores
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advantages of using bulk pallet boxes or bins |
saves storage space
reduced handling costs
adapted for long-term storage
adapted for terminal market repackers: citrus, apples, potatoes, sweet potatoes (onions) |
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What are fiberboard boxes? |
very widely used, reinforced cardboard
heavy enough, good protection, but under high Relative humidity, they loose rigidity |
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What is the relationship of fiberboard and relative humidity? |
fiberboard in equilibrium with 90% relative humidity has only 40% of its certified compression strength measured at 50% relative humidity
adding wax reduces this loss, but increases costs
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how can the rigidity of fiberboard boxes be increased? |
adding wax; adds costs
reinforcing corners of the boxes |
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What is more expensive? Fiberboard or Wood? |
Wood |
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T/F: you can print directly on fiberboard? |
True |
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What does it mean for fiberboard to be used as a "master container"? |
used to carry smaller units (typically poly bags) |
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What will they pack fiberboard boxes with? |
many vegetables, apples, citrus, pears; may pack with produce placed in moulded trays |
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How long have reusable plastic containers (RPC's) been used? |
15 years
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Advantages of reusable plastic containers (RPC's)? |
fold down for storability sides lock; good strength used for food safety because they are sanitizable high stacking capacity; optimum ventilation; washer friendly
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What material makes up reusable plastic containers (RPC's) |
polypropylene (PP) |
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What commodities still use burlap sacks? |
potatoes (100lb) and coffee
breathability |
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What are commonly packed in mesh bags? |
onions, cabbage, sweet corn (if not packed in wooden crates) |
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Characteristics of styrofoam boxes? |
can hold about 25 pounds of grapes
strong and light weight
insulate grapes well once cooled
also used in flowers and other high valued products
problem with recycling the box |
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what are styrofoam boxes made up of? |
polystyrene |
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What are packs used for? |
used to unitize product and are subsequently incorporated into a shipping container |
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Types of packs that are available |
Clamshells, punnets, mesh bags, lidded punnets, MA bags, Film sealed punnets, overwrapped trays (plastic trays), paper bags with mesh viewing, paper bags with perforated film |
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What points should all packing houses have in common? |
1. provisions for gentle handling of product
2. Methods to insure input efficiency
3. Methods to insure worker efficiency
4. Methods to ensure output efficiency
5. Management to ensure good average capacity. |
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What are the factors and facets of packinghouses? |
Location, layout, off-loading facilities, off-loading operations, packinghouse operations |
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What are the two most important factors involving location of a packinghouse? |
It must be centralized; near the majority of growing region
There must be access by road and/or rail depending on type of delivery and shipment system |
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T/F: If you are selling out of the backdoor of a packing house, you must have adequate parking available to consumers. |
True |
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What type of access is important to the success of packinghouses? |
access by road and/or rail depending on the delivery and shipment system
if you're selling out of the backdoor, you must have adequate parking
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What is the main criterion of designing a packing line? |
the desired capacity of the line |
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How should the layout of the packinghouse be designed? |
should allow for efficient flow of product without backtracking or cross-traffic from forklifts |
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Which is more expensive, increasing the length of a packinghouse or increasing the width of the lines? |
Increasing the length
Therefore, wide packing lines designed for maximum expected capacity (harvest) of the product is best |
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what are the benefits of wide lines in a packinghouse? |
cheaper than making packinghouse longer
wide lines can handle larger capacities at slower speeds than a narrow line
wider lines therefore allow for a greater flexibility in grading
wider lines allow for increased future capacity as the lines can be increased in speed to accomodate grater volume |
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Where does bruising and abraision most commonly occur in a packinghouse? |
where fruit turn corners or drop |
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What is the recommended angle of a turn in a packing line? |
angle of a turn should be no more than 30 degrees and should be padded |
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What could happen in a 90* turn in a packing line? |
causes build up of product in the turn |
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What is the recommended height of drops in a packing line if they must occur? |
6 inches or less; utilizing rubber sheeting or canvas to roll the product from conveyor to conveyor rather than having it drop |
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What should be considered if the product is being stored before entering the packing line? |
If a product stored before entering the packing line, storage area should be distant from the room where packed product is stored in order to minimize microbial contamination of clean product |
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Who decides and regulates the allowable amount of microbial activity in the air of packinghouses? |
OSHA (occupational safety and health administration) |
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Why should culls be kept away from packinghouses? |
reduce microbial load in packinghouse air |
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What is a common method of reducing the amount of microbial activity in the air? |
ozone generators |
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What is the key to the off-loading facilities of a packinghouse? |
must be able to handle incoming product quickly and efficiently |
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What are some ways to maximize the off-loading facilities of a packinghouse? |
scheduling: trucks do not accumulate in the yard waiting to unload
provide shade to prevent product from being burned and/or further warming
ideally offload and refrigerate product
ramps and docks should be wide, smooth and the right height
doors should be wide and high to limit the carefulness of fork lift drivers entering and exiting |
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Why might packinghouses store commodities such as carrots in cold storage for an extended amount of time before packing? |
Depending on the marketability of the product, it may not be beneficial to pack the product until the price per box goes up in the market.
It may not be worth packing at all, and product may get wasted; however it is still less loss than packing a product and underselling it or not selling it at all |
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What does the "wet method" of dumping in a packinghouse refer to? |
product is dumped into water to make it fast and easy to offload the product |
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What are the two methods to offloading product in a packinghouse? |
wet and dry method |
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What is "dry dumping" |
the offloading of a product into a dry bin |
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What is the difficulty and danger in dry dumping a product? |
must insure that the product flows from bin or gondola rather than falling. Use awnings or pneumatic doors to control the outflow of product from the bins |
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What must be considered when utilizing the "wet dumping" method of offloading? |
possibility of increasing decay during storage and/or shipment
is the commodity compatible with wet dump? |
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Why is it recommended to dump the fruit into warm water when wet dumping a product? |
this avoids infilitration of product by dirty water.
tomatoes are washed this way |
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What are common cleaning/washing practices in packinghouses? |
brushes, water containing detergent to remove trash, soil, sap, and pesticide residues.
rinse should contain chlorine or other disinfectant
excess water should be removed after cleaning using sponge rollers or air knives |
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what are common mechanical methods to sorting out off-type or diseased product? |
color and size sorters; acoustical system |
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Most common way to sort out damaged products? |
by hand |
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Why is adequate and proper lighting essential in packinghouses |
for laborers to clearly see the product as well as reduce worker fatigue |
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why are rollers used when sorting out bad product? |
turns product so that all sides may be viewed |
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How can one eliminate reaching and lifting for laborers that are sorting products? |
cull elimination chutes should be positioned at the same height as the conveyor
belt width should allow easy access to the center of the belt |
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What is important to incorporate into a packinghouse in order to reduce worker fatigue? |
provide stools of proper height, ear protection to limit noise fatigue, adequate lighting to reduce strain on eyes. |
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What are waxes commonly made out of? |
lipids, resins, proteins, carbohydrates, paraffin and mineral and vegetable oils |
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What are waxes and coatings used for? |
protection and appearance; also aids in limiting water loss
coating is not used for MA in most cases |
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T/F: coating is used for MA storage |
False; in most cases it is not used |
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examples of waxes and coating products |
beeswax, carnauba (wax from leaves of a palm), and candelilla (derived from leaves of candelilla shrub), wood rosin, casein protein from milk, zein protein from corn, wheat gluten, soy protein, whey proteins, cellulose derivatives, chitosan and various gums |
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what wax is made from the leaves of a palm? |
Carnauba - gives nice shine to apples |
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What wax/coating is derived from leaves of Candelilla shurbs? |
Candelilla |
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What wax is made from solid resin from pines? |
wood rosin |
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What is chitosan? |
a wax coating derived from the shells of crustaceans |
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T/F: coatings are used as modified atmosphere storage |
False
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What do coatings replace? |
natural waxes lost during washing |
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What is a common characteristic of a type of wax used on citrus |
it will carry a fungicide |
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How are waxes applied to a product? |
spray or drip and allowed to air dry or dry with forced air |
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How may waxes damage marketability of fruits? |
if it is misapplied, it will either cause cosmetic changes or development of deleterious internal modified atmosphere |
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What will precooling determine in a packinghouse? |
whether the prodcut will be stored or shipped immediately
may occur at any point in the packing line |
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What is the most cost efficient method of precooling in a packing line? (think about culling) |
more profitable to precool after initial removal of diseased or off-type product so you are not wasting energy on culls |
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how may products be sized? |
optical with a camera, rollers, weighing cups, sizing belts, etc. |
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most recently utilized size sorting system? |
optical cameras |
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What is unitization? |
taking smaller packs and consolidating them into a larger pack to aid marketing and increase ease of handling |
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What is palletization |
the orderly and directed arrangement of units on a pallet to facilitate shipping and marketing |
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How can unitizing and palletizing packages reduce mechanical injury to products? |
eliminates transfer of products |
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American pallet size |
40 x 48" |
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How is shifting of a load on a pallet minimized during transit? |
pallets are often banded or netted |
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How can boxes and cartons be consolidated? |
use hot glue to keep them together |
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What is the exact number of boxes/cartons/bags on a pallet directly correlated with? |
the size of the box/carton/bag |
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What does the configuration of boxes and cartons on pallets depend on? |
shape of the box, number of vents, allignment of vents and whether the produt will be precooled after unitization |
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What are the main functions of a packinghouse? |
sort, clean, grade, wax, cool and pack products |
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T/F: it is easier to build a good packinghouse than to redesign an existing one |
true; you should consult and plan before building |
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What is the most important storage invention since refrigeration? |
Controlled atmosphere storage |
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T/F: controlled atmospheres are a substitute for refrigeration |
false; it compliments refrigeration |
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Nitrogen, oxygen, and CO2 gas levels in CA storage |
N2 - more than 79%
O2 - 1-5%
CO2 - 1-5%, up to 10% |
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who built the first controlled atmosphere storage system? |
Dr. Smock at cornell |
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how much of apples in eastern washington state are stored in controlled atmosphere storage? |
2/3 |
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What commodities are stored in CA storage? |
pears - WA state
Cabbage in NY
Garlic (California) Gilroy |
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What products are currently being investigated for the use of CA storage? |
cherry, cranberry, and blueberry |
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What are factors that affect CA storage conditions? |
1. species of the plant
2.Temperature
3. Cultivar
4. Maturity of commodity
5. Preharvest environment
6.No single combination is good for all fruit |
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Temperature for apples stored in controlled atmosphere? |
45*F
any reduction of O2 will lower respiration rate at this temperature
at 32*F, oxygen levels must be below 8% to achieve a lower respiration rate |
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How long can apples be stored in CA storage compared to normal storage? |
8-12 months rather than 4-5 months |
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What are the methods of achieving controlled atmosphere conditions? |
Proper O2 and CO2 levels maintained
automatically controlled carbon dioxide, oxygen generators or scrubbers
continuous flow of externally generated CA gasses
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What level of CO2 is toxic to apples |
more than 5% |
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how much O2 will depleted in a gas tight room with apples stored in them? |
a gas-tight room full of apples may deplete O2 to 3% in 2-3 weeks |
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What methods are used to scrub CO2 from the room? |
hydrated lime
water scrubbing
caustic soda
molecular sieves
activated charcoal |
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What is produced when CO2 is scrubbed from a room using hydrated lime? |
CaCO3 - used for liming soils |
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How does water scrubbing work to remove CO2? |
water spray over evaporators or within room to absorb CO2
Water is circulated to outside where CO2 releases
Chill room where CO2 is released |
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What is the product when CO2 is scrubbed out using Caustic soda? |
Na2CO3 |
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What are molecular sieves and how are they used to scrub CO2 from rooms? |
Aluminum calcium silicate
CO2 adsorbed and driven off by electrical heat |
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How does activated charcoal remove CO2 from CA rooms? |
CO2 is driven off by passing fresh air through charcoal |
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What is a Tectrol generator? |
It is an oxygen scrubber that utilizes catalytic burning of propane to remove oxygen
excess CO2 is then scrubbed |
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How does Crack ammonia work to regulate gas in CA storage? |
Produces N2 and H2
Burn H2 to remove O2, raising levels of N2 |
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What is Pressure swing adsorption? |
PSA is pressurized zeolite beds producing N2, CO2 and C2H4
pressure is released to flush the rooms
N2, CO2, and C2H4 can be captured and used to flush the room of O2 once pressure is released |
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How are semi-permeable membranes used in CA storage |
Separates N2 from O2
smaller but less durable than PSA systems
use 99.999% N2 to flush the rooms |
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How is the continuous flow of externally generated CA gases useful in CA storage? |
it injects premixed gases using a mixing board to control gas levels. very fast and effective, but very expensive to purchase premixed gasses |
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What are the positive metabolic effects of CA storage? |
reduced respiration rate
lowered ethylene production
reduced ripening rate
retardation of decay
prevention of discoloration |
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Adverse Effects of CA storage |
Anaerobic respiration with too low of oxygen
off flavors and odors
tissue breakdown and/or browning
irregular ripening once removed from CA storage
CO2 injury
increased deay if CA mismanaged
will not support human life |
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When is Controlled atmosphere storage justifiable? |
if commodity is more desireable and hence more valuable than product stored for the same length of time under ambient atmosphere |
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T/F: Modified atmosphere storage is more accurate than CA |
False; much less accurate |
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Methods of achieving MA |
Passive, semi active, active |
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What is the passive method of achieving MA? |
allowing respiration to alter the package atmosphere |
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What is the semi-active method of achieving MA? |
replacing the package atmosphere with a pre-determined gas mixture to rapidly achieve the MA condition desired |
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What is the active method of achieving MA? |
Packages contain a pad or sachet which either absorbs oxygen or emits CO2 |
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What is true about plastic films and modified atmosphere storage? |
all plastics have some gas permeability
must be properly used to be effective
not a substitute for refrigeration
recent resurgence in research do to increase in lightly-processed, fresh vegetable and fruit products
widely used at retail level
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Advantages of MA storage |
can create modified atmospere
reduced water loss; most often primary use of packaging
protection from mechanical damage
improved product appearance
sanitation (eliminates dirt, insects, handling problems)
convenience (preweighed)
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What is the most common reason for using modified atmosphere packaging? |
reduce water loss |
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What acts as an insulator in Modified atmosphere packaging? |
air |
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What are the types of plastic films used in modified atmosphere packaging? |
stretchable films (trays of vegetables)
heat-shrink films
heat-sealable films
cellophane
polylactides
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what are some important considerations when choosing a plastic film for modified atmosphere packaging? |
Clarity (transperancy)
tensile strength
%stretch
stiffness
heat shrinkability
water vapor transfer rate
gas transfer rate
resistance to grease, oil
flammability
sealability -- heat, adhesive, solvent
Migration
cost |
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What does the tensile strength of a commodity refer to? |
ability to be stressed (pulled apart) without breaking |
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What does % stretch mean in plastic films? |
ability to deform (not breaking) |
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What is migration in terms of plastic films? |
movement of hydrocarbon monomers, oligomers, and or additives from plastic into package and onto product |
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What problems stem from the use of plastic films or bags? |
consumer may feel decieved when opening product
wrong packaging could damage product
development of off-odors and flavors (acetaldehyde, ethanol)
discoloration of tissues (antioxidants and antibrowning agents used to control)
undesirable textural changes |
