Maturity Indices in fruits
and vegetables
Dr. Soni Gupta
Assistant Professor
Program: M.Sc Food Technology
(MFT-2001)
Maturity
• It is the stage of full development of
tissues in fruits and vegetables after
which ripening starts
• During the process of maturation the fruit
receives a regular supply of nutrients from
the plant
• When mature the abscission/ corky layer
at the base of the stem stops this inflow.
• The fruit after wards depends on its own
reserves
Maturity
• The stage of maturity at which the
fruit is plucked influences the storage
life and quality of fruits
• If harvested early: may lack flavor, and
do not ripen properly
• If plucked late: may be fibrous or have
very short shelf life
Maturity
Categories:
• Physiological maturity
• Horticultural maturity
Horticultural or Commercial maturity
• Stage of development when plant parts
possess necessary characters preferred
by consumers
• Depends upon intended use e.g. papaya,
jackfruit
Physiological maturity
•End of development stage
•Ability to ripen normally after harvest
Maturity and shelf life
• Quality is maximized when harvested at more
mature and ripe stage but shelf life increases
when harvested at unripe stage
Lower maturity Higher maturity
Never ripens More decay
Shrivels Better flavor
Poor flavor Too soft
No repeat buys Bruises easily
Long shelf life Short shelf life
Maturity indices
• Maturity indices= harvest indices
• Sensory and nutritional quality
• Adequate shelf life
• Facilitate marketing standards
• Productivity
Types of maturity indices
•Visual indices Calculated indices
a) Shape a) Calender dates
b) Color b) Days after full bloom
c) Heat Units
•Physical indices
a) Firmness
b) Accoustic sound test Physiological Method
c) Specific gravity a) Respiration rate
b) Ethylene peak
Chemical indices c) Volatile production
a) Total soluble solids
b) Titrable acidity
Size and shape
Fruit shape may be
used to ascertain
maturity:
Mango:
Fullness of cheeks
adjacent to pedicel
maybe used for
ascertaining maturity
Banana:
Angular shape becomes
more round
Colour
Use of colorimeter
Firmness
Middle lamella dissolves as fruits
mature; become soft
Fruits: apple pear, plum, guava,
pear, kinnow etc.
Penetrometer helps measure the
pressure required to force a
plunger of a specified size inside
the fruits tissue.
Such pressure is measured as
pounds or kilograms force.
Accoustic/ Sound tests
When a fruit is tapped with finger
knuckles at immature and ripened
stages, it produces sounds of different
quality
Ripe fruits give dull sound
E.g. Watermelon, Jackfruit
Specific Gravity
Ratio of the substance to the ratio of reference substance
As fruits mature their specific gravity increases
Useful for grading fruits according to maturity
If placed in tank full of water:
Fruits that sink: more mature
Fruits that float: less mature
Specific gravity of fruits and vegetables= Weight of fruits and vegetables in air
Weight of fruits and vegetables in water
Total Soluble Solids
Starch is broken down into
sugars during ripening
Measurement of sugar
content gives an idea of
maturity
Measured by Brix
refractometer
Measures the refractive
index of fruit juice
Has a range: 0-32°B
28-62°B
56-90°B
Titrable Acidity
Days after full bloom
It is reliable but varies from year to year and
location to location
In such cases, the optimum date of harvest can be
predicted by doing night temperature correction for
15 days following full bloom. For every 10 F variation
from an average night temperature, a correction of 1
day is made in the standard figure from full bloom.
Mango: 110-125 days (Var. alphanso and Pairi)
Banana: 99-107 days (Dwarf Cavendish)
Heat Units
All plants have a tolerable growth temperature range
Higher is the temperature in this range, faster is ripening or
earlier harvest
Principle: If everything remains same, the time a fruit takes to
fully develop is dependent on the surroung temperature
Expressed in degree-hours or degree-days
Degree-hour: is the accumulated heat unit equivalent to the
exposure of the crop to one degree above the reference
temperature for one hour.
Degree-day: : is the accumulated heat unit equivalent to the
exposure of the crop to one degree above the reference
temperature for one day.
General formula:
Mean heat units= (Actual temperature-Reference temperature) x time
Example
Base temperature=40°F
Day temperature-60° F
Each hour constitutes= 60-40= 20 degree
hours
Average temperature in a day=55°F
Equivalent = 15 degree days
1200 degree days required for peas from
planting to maturity
So, 1200/ (55-40)= 80 days from planting
to harvest
Heat Units
•Planning
•Planting
•Harvesting
•Factory programs
Corn, peas and tomato for processing
Respiration Rate
Particularly useful in
climacteric fruits as
there is a sharp increase
in respiration rate;
helpful in pin pointing the
most appropriate time of
harvest
Climacteric pattern of respiration
Determination of
respiration peak can help
in determining the
maturity of the product.
Ethylene peak
Climacteric fruits
have ethylene peak
Helpful in determining
the maturity stage
for harvesting
Volatile production
Apple: Ethyl-2 -methyl butyrate
Banana: Eugenol
Grapefruit: Nootaketone
Lemon: Citral
Orange: Valencene
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,
respiration and ethylene production, production of volatiles etc.)
Features of maturity indices
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
•Permits prediction of maturity from year to year
•Inexpensive
Advantages of estimation of maturity
•To maintain the quality of the product
•To enhance the freshness, appearance and
elegance of the produce
•Improvement in the storage life of produce
•Management of ripening and senescence
(hasten/ delay harvesting)
•Extended utilization of the produce
•For long distance transportation of produce
•To maximize returns
• Limitations of maturity indices
– Soil conditions, nutrition, irrigation
– Season , climate
– Position on the plant
– Pruning and other cultural practices and
management practices
– varieties
