At the end of the lesson, the learners are expected to:
1. enumerate the various postharvest procedures;
2. define maturity index;
3. determine the maturity indices of common fruits and
4. discuss the importance of maturity indices in postharvest
5. differentiate physiological from horticultural maturity; and
6. enumerate the different harvesting practices of common fruits
1.Procedures in Postharvest Handling of
Fresh Fruits and Vegetables
2. Definition of Maturity Index
3. Maturity Indices of Common Fruits and Vegetables
4. Importance of Maturity Indices in Postharvest Handling
5. Differences between Physiological and Horticultural
6. Harvesting Practices for Common Fruits and Vegetables
In postharvest physiology, maturity is
considered as "that stage at which a commodity has
reached a sufficient stage of development that after
harvesting and postharvest handling, its quality will
be at least the minimum acceptable to the ultimate
consumer" (Reid, 1992).
Definition of Maturity
Fruit and vegetable quality is a combination of
attributes and properties that give them value in
terms of human consumption.
Growers and shippers are concerned that their
commodities have good appearance and few
To receivers and distributors, firmness and a
long storage life are of keen importance
The optimum maturity at harvest is a
very important determinant to the final
quality of the product.
Fruits and vegetables picked too early or too
late in season are more susceptible to
physiological disorder and have a shorter
storage- life than those picked at the proper
Fruits picked immature may not fully ripen.
Maturity indices are used to determine
maturity, to predict harvest date and to
assess quality of crop, for example is the
crop suitable for fresh or processed
Based upon a range of physical and
chemical properties of the crop ideally
should be simple to use and be non-
Maturity indices require sets of quantifiable
guidelines for determining maturity and quality of
Practical uses of Maturity Indices
1) Export markets often include a guide for minimum
and maximum maturity that is acceptable for a
2) Marketing strategies to obtain premium prices for
commodities “Supply and demand” delaying or
expediting harvesting and shipping of a particular
crop at the beginning or end of the season requires
a measure of maturity if quality is to be maintained
3) Efficient use of labor. A measure of maturity is
important for organizing start and end dates for
harvesting to ensure labor and equipment availability
and reduce harvesting costs
Physiological maturity versus
Plant (part) has completed natural growth and development
Certain stage of development so that upon harvesting from the
plant commodity will continue to develop as if still on plant
Quality has reached minimum acceptable standards
Stage of development when a plant possess the quality
prerequisites for use by consumers for a particular
Commodity can be horticulturally mature at any stage of
development or physiological maturity
All plant (parts) are harvested when
horticulturally mature but may be
physiologically immature or mature
Examples of mature hort. / immature phys.
crops: sweet corn, peas, snap beans,
summer squash, cucumber and bean
Examples of mature hort. / mature phys.
crops: winter squash, melons, tomato,
Types of maturity indices
1) Number of days from planting to maturity
2) Days from full bloom to harvest
Types of maturity indices
External and internal color;
useful for many horticultural products
Color charts produced for
color using a
Size; May not be a good indicator of
maturity as can be influenced by
many factors but useful for peas,
beans, potatoes, celery
Shape; Some crops are harvested when
reaching a certain shape. For example
banana (3/4 full, full ¾ and round full),
Solidity- head lettuce and cabbage
are harvested on the basis of the
solidity of the head
1) Firmness - (apples, pears, peaches)
used to determine harvest date and to
2) Tenderness - measured with
tenderometer - peas
1) Development of an abscission layer – muskmelons
2) Development of a waxy layer on the epidermis –
plums, grapes, honey dew melons
3) Development of netting on the surface –
4) Internal structure - formation of gel-like material
surrounding the seeds of tomatoes
5) Prior to tip opening - asparagus
Development of an abscission layer in
1) Starch - apples, pears
2) Soluble solids /Sugars - apples, pears, stone fruits,
3) Acids; sugar/acid ratio – citrus, pomegranates, kiwifruit
4) Juice content - citrus fruits
5) Per cent dry weight- avocado
6) Astringency –persimmon, dates –low levels desirable
7) Ethylene production – apples, pears (particularly those
destined for long term storage)
Starch content in apples
particularly useful for green apples eg. Granny Smith
Measurement of soluble solids (°Brix)
An optical instrument that is used to determine the refractive index of
a substance. Can be used to determine the identity of an unknown
substance based on its refractive index to assess the purity of a
particular substance, or to determine the concentration of one
substance dissolved in another.
Degrees Brix (symbol °Bx) is a measurement of the mass ratio of
dissolved sucrose to water in a liquid. It is measured with a
refractometer. A 25 °Bx solution is 25% (w/w).
Minimum maturity index:
NZ kiwifruit 6.25 %
Passion fruit 14 – 18 %
Cantaloupe (U.S. Fancy) 11 %
Cantaloupe (U.S. No. 1) 9 %
Non-destructive maturity analysis
Used to detect aroma volatiles in a range of food types.
Has been used for determining fruit maturity based on
the production of aroma volatiles. Statistical analysis
must be performed to interpret data. Most research
literature is based upon method verification and comparing
data with more
established methods of evaluating maturity.
Acoustic firmness sensor
Method taps the fruit and then “listens” for vibrations
(resonance attenuated vibration). Fruit of different
maturities produce different vibration profiles. Measures
whole product not just a restricted area.
Non-destructive maturity analysis
Various different methods based upon the
atoms or molecules with the electromagnetic
1)Visible spectral imaging (380 – 770
nm). Measuring surface
color based on absorption of light energy by
in chlorophylls, carotenoids and anthocyanins.
Used in packing
lines to detect color of apples and peaches.
2)Fluorescence imaging Achieved by
radiation in the visible range following
excitation with short
wavelength radiation. Greatest use of
application is in the
measurement of chlorophyll fluorescence.
Non-destructive maturity analysis
Near infrared spectrophotometry (NIRS) (750 nm –
Suitable for measuring compounds containing OH-, CH-
and NH- groups.
Extensively used in the food industry. Can be used to
acidity, brix and color of fruits. Commercial packing line
Available (10 pieces fruit per second) and handheld
machines are being developed.
NMR and MRI imaging
Abbott 1999 Postharvest Biology and technology 15:
Can be used but equipment is sophisticated
and expensive and speed is too slow for
The definition of maturity as the stage of
development giving minimum acceptable quality to
the ultimate consumer implies measurable points
in the commodity's development, and the need for
techniques to measure maturity.
Why we need maturity indices
The maturity index for a commodity is a
measurement or measurements that can be used
to determine whether a particular commodity is
These indices are important to trade regulation,
marketing strategy and to the efficient use of labor
Maturity at harvest is the most important factor
that determines storage-life and final fruit
Immature fruits are more subject to shrivelling
and mechanical damage, and are of inferior
flavour quality when ripe.
Overripe fruits are likely to become soft and
mealy with insipid flavour soon after harvest.
Fruits picked either too early or too late in their
season are more susceptible to postharvest
physiological disorders than fruits picked at the
All fruits, with a few exceptions (such as pears,
avocados, and bananas), reach their best eating
quality when allowed to ripen on the plant.
However, some fruits are usually picked mature but
unripe so that they can withstand the postharvest
handling system when shipped long-distance.
Most currently used maturity indices are
based on a compromise between those
indices that would ensure the best eating
quality to the consumer and those that
provide the needed flexibility in marketing.
Fruits can be divided into two groups:
1)fruits that are not capable of continuing their
ripening process once removed from the plant,
2) fruits that can be harvested mature and ripened
off the plant.
Group 1 includes duhat, watermelon, rambutan,
durian, lanzones, caimito, mabolo,aratiles,
camachile,cherry, citrus fruits, grape, lychee,
pineapple, pomegranate, guava and tamarind
Group 2 includes apple, langka, avocado, banana,
cherimoya, kiwifruit, mango, nectarine, papaya,
dragon fruit, pear, peach, persimmon, plum, tiesa,
Group 1 fruits produce very small quantities
of ethylene and do not respond to ethylene
treatment except in terms of degreening
(removal of chlorophyll); these should be
picked when fully-ripe to ensure good flavour
Group 2 fruits produce much larger
quantities of ethylene in association with their
ripening, and exposure to ethylene will result
in faster and more uniform ripening.
The quality of fruits and vegetable cannot be
improved but it can be presented when harvesting is
done at proper stage of maturity.
The quality of fruits and vegetable cannot be improved but it
can be presented when harvesting is done at proper stage
of maturity. Immature fruits when harvested will give poor
quality and erratic ripening.
In some cases, if the produce is to be shipped to
distant markets, or stored, to wait for a better
price, it should be picked in the mature but unripe
Here lies the difficulty, because unlike the ripening
stage, the boundary between pre maturation and
maturation stage is hard to detect.
No prominent changes in firmness or colour are
evident often harvest indices becomes arbitrary
Maturity can be described as the attainment
of the particular size or stage after which
ripening takes place.
On the other hand, ripening means the
qualitative changes in fruits after maturity of
which it become edible.
i) Number of days from fruit
ii) Visual indicators,
iii) Size of fruits,
iv) Shape of fruit,
v) Colour of fruit,
vi) Appearance (External)
viii) Lenticel number
ix) Specific gravity
x) Starch Content
xi) Soluble solids
xii) Sugar acid ratio
xiii) Oil content
Various Maturity Indices are:
There are five types of indices to judge the
maturity of the fruit.
1. Visual means
2. Physical means
3. Chemical analysis
5. Physiological method.
Types of Maturity of Fruits and
A) Harvesting Maturity
B) Physiological Maturity
C) Commercial or Horticultural Maturity
The harvest maturity of vegetable depends
upon the purposes for which it is harvested.
For local market and for processing, fully
coloured tomato fruits are harvested.
However, for a distant market fruit which
have started developing colour are
The post-harvest quality and storage life of
fruit appear to be controlled by the maturity.
If the fruits are harvested at a proper stage
of the maturity the quality of fruit is
The post-harvest quality and storage life
of fruit appear to be controlled by the
maturity. If the fruits are harvested at a
proper stage of the maturity the quality of
fruit is excellent.
Poor quality and uneven ripening are
caused by early harvesting and late
harvesting result in extremely poor shelf life.
It is imperative that the fruit should be at the
right stage of the maturity with no physical
Various Maturity Indices such as number of
damage from fruit set, visual indicators,
size, shape, colour, appearances, texture,
lenticel number, specific gravity starch
contain soluble solids, sugar, acid ratio and
oil content are used to determine maturity of
Commercial or Horticultural Maturity:
It is a stage of fruit and vegetable at which consumer
wants the fruit and vegetable or fruit and vegetable
require by market. The horticultural maturity of fruits and
vegetables depends upon the purpose for which it is
Example: The okra pod is matured when it is tender
with maximum size, as per horticultural maturity.
2. It is a stage between development and
growth of any plant part.
3. It can be predicted by using different
terminology like premature, mature and over
4. There is no necessity of senescence.
Harvesting is one of the important operations,
that decide the quality as well as storage life of
produce and helps in preventing huge losses
Harvesting of fruits should be done at
optimum stage of maturity
Harvesting of Fruits and Vegetables
During harvesting operation, a high standard
of field hygiene should be maintained.
It should be done carefully at proper time
without damaging the fruits.
The harvesting operation includes.
i) Identification and judging the maturity of fruits.
ii) Selection of mature fruits.
iii) Detaching or separating of the fruits from tree,
iv) Collection of matured fruits.
Method of Harvesting:
Different kinds of fruit and vegetables require
different methods after harvesting. The
methods of harvesting are:
2. Mechanical Harvesting
Harvesting by one’s own hand is called manual
harvesting. It is done in several ways:
a. Ladder / bag picking method
b. Poles/ Clippers method
c. Harvesting by means of cutting knives
d. Harvesting by means of digging tools.
2. Mechanical Harvesting:
In this method numbers of mechanical
devices are used for harvesting the
produce on commercial scale.
• inappropriate maturity at harvest (over ripening
increases sensitivity to quality decay ;
immature fruits market rejection).
• inappropriate harvest technique (mechanical
• climatic conditions at harvesting (free water,
exposition of product to direct sun light )
• harvesting wet products (increase sensitivity
to quality decay)
• inappropriate harvesting containers
( physical injuries).
Associated hazardsAssociated hazards
• training personnel on optimum maturity indices.
• Application of appropriate maturity indices based on: external
quality color, consistence, phenological stage, etc.
• Harvesting time: early in the morning or late in the afternoon in
order to minimize the sun effect.
• Optimizing harvesting recipes/containers (size, materials,
height, number of produce layers, conditions, etc. )
• protection of product of direct sun intensity.