maturity indices of fruits and vegetables

2. Maturity indices of fruits and
vegetables

3. MATURITY
 It is the stage of fully development of tissue of fruit and
vegetables only after which it will ripen normally
 During the process of maturation the fruit receives a
regular supply of food material from the plant
 When mature, the abscission or corky layer which forms at
the stem end stops this inflow
 Afterwards, the fruit depend on its own reserves

4.  In addition to this, typical flavour and characteristic colour
also develop
 It has been determined that the stage of maturity at the
time of picking influence the storage life and quality of fruit
 when picked immature like mango develop white patches
or air pockets during ripening and lacking in normal brix
acid ratio or sugar acid ratio, taste and flavor
 on the other hand if the fruits are harvested over mature or
full ripe they are easy susceptible to microbial and
physiological spoilage and their storage life is considerably
reduce

5.  Such fruits persist numerous problems during handling,
storage and transportation
 Therefore, it is necessary or essential to pick up the fruits
or vegetables at correct stage of maturity to facilitate
proper ripening, distant transportation and maximum
storage life
 The postharvest quality of the product is fixed at the
harvest so proper harvesting is necessary
 We can have good harvest if we harvest at proper time as
the development of the fruits is at later stage of
development

6.  Fruits harvested too early may lack flavor and may not
ripen properly, deteriorate faster and have short shelf
life
 while produce harvested too late may be fibrous or have
very limited market life
 Yield may also be lower
 Therefore harvesting of fruits and vegetables at proper
stage of maturity is of paramount importance for attaining
desirable quality
 The maturity has been divided into two categories i.e.

7.  Horticultural maturity/Commercial maturity
 Stage of development when plant parts possess the
necessary characteristics preferred by consumers
 Depends on the intended use e.g. papaya, jackfruit
 Physiological maturity
 Applies only to fruits and fruit vegetables
 End of development stage
 Ability to ripen normally after harvest
for distant market and storage,
o climateric fruits should be harvested at maturity before they
are ripe i.e. before climateric rise
o Non climateric fruits should be harvested at ripe stage

8. Importance of maturity indices
 Maturity indices = harvest indices
 Sensory and nutritional quality
 Adequate shelf life
 Facilitate marketing- standards
 Productivity

11. Too often we are on the side of shelf life at the
expanse of good eating quality

12. Maturity indices
 Sign or indications of the readiness for harvest
 Basis for determining harvest date
 Two types of maturity indices
i) Subjective:
 Qualitative
 Use the senses (color, size, shape, sound, firmness, juice
content etc.)
ii) Objective:
 Quantitative
 Are measurable indices (TSS, TA, Starch content, oil content,
firmness, dry matter, Days after full bloom, heat degree day,

13. Types of indices
i) Visual indices
a) Size and shape:
 Maturity of fruits can be assessed by their final shape and size at
the time of harvest.
 Fruit shape may be used in some instances to decide maturity.
 For example, the fullness of cheeks adjacent to pedicel may be
used as a guide to maturity of mango
 Banana : angular shape changes to round

14. b) Colour:
 The loss of green color of many fruits is a valuable guide to
maturity

15. ii) Physical indices
a) Firmness:
 As fruit mature and ripen they soften by
dissolution of the middle lamella of the
cell walls.
 In many fruits such as apple, pear,
peach, plum, guava, kinnow etc. firmness
can be used to determine harvest
maturity.
 Penetrometer measures the pressure
necessary to force a plunger of specified
size into the pulp of the fruit.
 Such pressure is measured in pounds
and kilograms force.

16. b) Specific gravity:
Specific gravity is the ratio of the density of a substance to the
density of a reference substance.
As fruit mature, their specific gravity increases.
This parameter is rarely used in practice to determine when to
harvest a crop
It is used to grade crops into different maturities.
To do this the fruit or vegetable is placed in a tank of water;
those that float will be less mature that those that sink.
In practice, the fruit or vegetable is weighed in air, then in pure
water. The weight in air divided by the weight in water gives
the specific gravity.

17. iii) Chemical Measurement
 The total soluble solids of the fruit can be measured with
refractometer, which indicate the harvest maturity of fruits.
 Acidity is readily determined on a sample of extracted juice by
titration with 0.1 N NaOH.
 TSS/TA is better to judge maturity as it gives the sugar acid
blending of product
a) Total Soluble Solids
 can be determined in a small sample of fruit juice using hand
refractometer
 The refractometer measures the refractive index, which
indicates how much a light beam will be slowed down when it
passes through the fruit juice.
 The refractometer has different scales (0-32OB), (28-62OB) and
(56-92OB) which can be read directly.

18.  For large size fruits, these should be cut from stem to blossom
end and to the centre of the fruit to account for variability in TSS
from top to bottom and inside to outside of the fruit.
 The fruit tissues should be macerated thoroughly in pastle motor
and then from the mescerated pulp the juice is extracted by
passing through muslin cloth.
 A drop of juice is then put on the prism of the refractometer and
TSS content can be read directly on the scale.
 However, in case of small fruits like grapes, the juice content
can be extracted by simply pressing the whole fruit.

19. b) Titratable acidity:
Titratable acidity (TA) can be determined by titrating a know
volume of juice with 0.1N NaOH to end point
The milliliters of NaOH needed are used to calculate the TA.
The TA expressed as percent malic, citric or tartaric acid can
be calculated as follows:

20. iv) Calculated indices:
a) Calendar Date/Days after full bloom :
Useful guide to harvest, where seasonal variation in climate is
small
This method works well when the blooming period is short
period
b) Heat Units:
It has been found that a characteristics number of heat unit or
degree-days is required to mature a crop under usually warm
conditions
It is based on the principle that growth of plant organ is
directly proportional with ambient temperature

21. V) Physiological Method:
Respiration rate:
 Particularly on climateric fruits can accurately pin point the
most appropriate time of harvest as there is climateric rise
in respiration
Internal ethylene evolution:
 Like respiration rise climateric fruits also have ethylene
peak
Volatiles production:
Apple: Ethyl-2-methyl butyrate
Banana: Eugenol
Grapefruit: Nootaketone
Lemon: Citral

22.  Maturity indices should be
 simple, easy to carry out
 Objective vs subjective indicators
 Related to quality
 Related to storage life
 Represents a progressive change with maturity
 Premits prediction of maturity from year to year
 inexpensive

23.  Limitations of maturity indices uses
 Soil conditions, nutrition, irrigation
 Season , climate
 Position on the plant
 Pruning and other cultural practices and
management practices
 varieties