Lecture 17: Quality and Maturity Indices Harvesting Methods Flashcards
define quality
combination of various physicochemical and nutritional characteristics that give them value as a food item
what are components of food quality?
- appearance or visual factors
- texture or mouth feel
- flavor
- nutritive value
- safety or antinutritional factors
what are types of defects?
- morphological: sprouting, seed germination
- physical: shrivelling and wilting
- mechanical: punctures, cuts, abrasion
- physiological: chilling and freezing, internal breakdown
- pathological: fungal and bacterial
- entomological: damages by insects and pests
what are the perceptions and priorities or quality in the produce chain?
everybody: appearance factor
plant breeders and farmers: yield and resistance to disease
consumer: appearance, firm, good flavor, nutrition
what are quality factors imp for?
setting standard specifications
what genetic factors influences quality?
cultivars
rootstocks
selection of specific varieties
GMO
what are environmental factors that influences quality?
climate (temp, light, rainfall, irrigation, wind)
cultural (soil type, water supply, pruning, thining, pesticides, growth regulators)
what is TR?
tolerance range
within the TR, higher temp = ____ growth = ____ harvest
faster growth and earlier harvest
what is temp summation
indicator of harvest maturity (degree day - heat unit)
what can heat units be expressed as?
degree hour or degree days
define a degree hour
accumulated heat unit equivalent to the exposure of the crop to one degree above the reference temp for one hour
define a degree day
exposure at one degree above the reference temp for one day
what temperatures for day and nights are ideal for plant growth?
what climates is this?
warm days ( greater photosynthetic activity and better storage of food reserves)
and cool nights (lower resp; lower depletion of stored reserve)
temperate climates
describe how tropic climates is diff than temp climates. what does this cause?
in tropic climates, night temp is around the same as day temp
causes diff fruit quality (higher accumulation during the day and higher depletion of stored reserves during night)
how does duration of light affect quality?
longer day and shorter nights = more photosynthetic activity = less depletory activity = better
how does intensity of light affect quality
higher intensity = higher sweetness = lower acidity
higher intensity also causes fading of colors
how does canopy shading affect tomatoes and cucumbers?
deeper colors
how does density of planting influence light intensity?
high intensity planting = lower exposure to light = lower photosynthetic activity = lower sweetness
quality of light is imp for what?
pigmentation
how do purple cabbage or eggplant derive their color rom?
what if they have direct exposure to light?
exposure to blue and violet light
direct exposure = green color
what are other environmental factors that affect quality?
rainfall
soil texture
wind factors
what kind of effects does pesticides have on quality?
undesirable (low TSS and high acid)
what is abscission preventing for?
to control fruit drop
includes 2,4,5 T, NAA, CPA, Alar
what are three main Q’s imp for harvest and maturity
- which parameters can be used?
- how does the parameter relate to maturity
- how can the parameter be used to predict maturity?
define optimum maturity
stage where a commodity has sufficient development that after harvesting and post harvest, the quality will be acceptable to consumers
what are indices of maturity and quallity?
- elapsed days from full bloom
- meat heat units
- size
- specific gravity
- solidity
- texture properties: firmness, hardness…
- chemical tests: starch, sugar, ascorbic acid, etc…
define harvesting
processo f detaching a produce
how should harvesting be carried out?
- at proper maturity stage
- proper technique
- as fast as possible
- with minimum damage or loss
what are advantages and problems of hand harvesting?
adv
- selective pickings
- min damage
- min capital investment
- output = # of people at work
problems
- shortage of labor
- labor strikes are costly
- permanent labor force is not feasible
- need efficient labor management
describe mechanized harvesting
- used for crops intended for processing
- produce is converted to other forms
- physical appearane is not a major consideration
- commodity is consumed within short time and normally needed in bulk
what are advantages of mechanical harvesting?
- speed of harvest
- improved condition for workers
- reduced labor problems
what are incentives for mechanical harvesting?
- increased cost of manual labor
- decreased availability of timely labor
- need ofr high speed high volume output
what are disadvantages of mechanical harvesting?
- physical/mechanical damage to crop
- non selective
- separation of plant debris
- damage to fruit trees during harvesting
- large volume output
- machinery expensive
- social impact
what are imp elements of harvesting?
- detection
- selection
- detachment (mechanical or hand)
- collection
- separation
- handling
what are field considerations for mechanized harvesting?
- genetic considerations (tree, crop, strength)
- plat system and tree training (high density)
- crop control (pruning and fruit thinning)
- harvest control (pre harvest sprays)
what are harvest sprays?
what roles do they have? examples of each role
growth regulator
roles
- increases size of fruit: Alar, ethephon, GA
- sprout inhibitor: MH (maleic hydrazide), MENA (methyl ester of NAA)
- fruit thinning: NAA, CPA, ethyphon
what are types of mechanical harvesters?
- direct contact devices: cutting, pulling, snapping, twisting, etc…
- vibratory devices: trunk and limb shakers with catch frame and cavas
describe harvest aid. What are examples?
mechanical device/support which assists in improving hard harvest operations
ex
- picker pole with knife and canvas bag
- station platforms to position workers
- conveyor belt to hmove harvested produce
- harvesting cages
- lights for night harvesting
differentiate the extent of mechanization in fresh market vs processing
fresh: less than 25%
processing: more than 75%
