quality criteria for fruit and vegetables

1. Quality Criteria of Fruit and Vegetables
 What is quality?
The totality of features and characteristics of a product
that bear on its ability to satisfy stated or implied needs
 Safety
Assurance that food will not cause harm to the
consumer when it is prepared and/or consumed
according to its intended use
 What is shelf-life?
defined as the period within which the product retains
‗acceptable quality‘ for sale to the processor or
consumer
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2. Cont…
 Appearance
key factor for consumers in making purchases of
fresh produce
includes shape, size and color
Factors reducing this quality:
Mechanical damage - browning reactions
Diseases
Loss of freshness – wilting of leafy vegetables
Yellowing of green leafy vegetables
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3. Quality Criteria of Fruit and Vegetables
 Feel (touch)
Manual evaluation of firmness and texture. May be
accompanied by mechanical texture analysis
 Defects
Visual evaluation of absence of defects or deterioration of
colour May be accompanied by mechanical methods (for e.g.
ultrasound)
 Odour
 Mostly qualitative and subjective evaluation by smelling. May
be accompanied by technical methods (gas chromatography)
 Taste
Oral tasting (sweetness, bitterness, sourness and saltiness)
Technical quantification of taste compounds (for example
chromatography)
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4. Quality Criteria Of Fruit And Vegetables
 Texture
Eating quality includes a complex of textural
properties which are not readily defined or measured
Crisp firm tissues are generally desired in vegetable
crops;
development of tough fibers during storage in stem
crops such as asparagus is not at all acceptable
some degree of softening is required for optimal
quality in fruit;
over softening is undesirable and is a sign of
senescence or internal decay
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5. Cont…
 Flavor and aroma
Flavor is a complex of taste and aromatic
components.
taste components - sweetness, acidity, astringency
& bitterness
aroma can be determined to some extent before
purchase by the consumer (e.g. only in highly
aromatic products - melons or mangoes)
 Wholesomeness
 Wholesomeness is difficult to measure objectively; it
can be described as ―freshness‖ ―produce integrity‖; it
also has a ―sanitary‖ component meaning how clean /
hygienic the product is.
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6. Quality Criteria of Fruit and Vegetables
Nutritive value
Nutritive value is measured by the content of nutrients
such as fat, carbohydrates, protein as well as essential
vitamins, minerals and other substances that influence
human well-being.
 Food safety
Food safety can be measured via the examination of
food items with regard to their pathogenic microbial
load, content of chemical contaminants or presence of
physical foreign matter in the produce.
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7. General Class of Fruit and Vegetable
Quality Attributes (Criterion)
 External
Appearance
Feel or touch
 Internal and
Taste
Odour
Texture
Flavour and aroma
External attributes play an important role in a consumer's
purchasing decision, whereas internal or hidden attributes
often affects a consumer's decision to repurchase a product.
The combination of external, internal and hidden attributes
determines the overall acceptability of a product.
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 Hidden
Wholesomeness
Nutritive value and
Food safety

8. Grading, Standard and Inspection of
Fruit and Vegetables
 Grade standards identify quality attributes in a commodity
that are the basis of its use and value.
 Standards provide common frames of reference for
defining products
 Such standards, if enforced properly, are essential tools of
quality assurance during marketing and provide a common
language for trade among growers, handlers, processors,
and receivers at terminal markets
 Grading usually does not imply criteria for food safety.
Grading standards are developed and adopted either by
private industry or national bodies and might be
mandatory for export. 84

9. Cont…
 Fresh produce is inspected by either governmental
agencies or other authorized bodies to ensure a product's
adherence to regulations regarding quality,
wholesomeness and food safety or specific mandatory
requirements within the supply chain. Inspection is
usually mandatory and involves official authorities
 Grading is a voluntary program of the food industry for
product classification based on mostly external attributes
and characteristics. Grading does not usually pertain to
food safety.
 Inspection is generally a mandatory process conducted
by governmental authorities or other agencies to ensure a
product‘s wholesomeness, safety and adherence to
regulations. 85

10. Factors Influencing Quality and Safety
of Fruit and Vegetables
A. Genetic Factors
 Within each commodity grouping there is a range of
genotypic variation in composition, quality, and post-
harvest-life potential.
 Genetic manipulation has contributed to improving the
quality of fruits and vegetables
 Many opportunities exist for applying biotechnology to
improving the post-harvest quality and safety of fresh
produce. Priority goals in this regard, should, be focused
on:
1. Attaining and maintaining good flavor and nutritional
quality, so as to satisfy consumer demands and
2. Introducing resistance to physiological disorders and/or
decay-causing pathogens, so as to reduce the use of
chemicals on fruits and vegetables. 86

11. B. Climatic Conditions
 Climatic factors, in particular temperature and light
intensity, greatly impact on the nutritional quality of
fruits and vegetables.
 Consequently, the location of production and the season
in which plants are grown can determine their ascorbic
acid, carotene, riboflavin, thiamine, and flavonoid
contents.
 In general, the lower the light intensity the lower the
ascorbic acid content of plant tissues.
 Temperature influences the uptake and metabolism of
mineral nutrients by plants, since transpiration rates
increase with increasing temperature 87

12. Cont…
 Rainfall affects water supply to the plant, which may influence the
composition of the harvested plant part and its susceptibility to
mechanical damage and decay during subsequent harvesting and
handling operations
C. Cultural Practices
 Soil type, the rootstock used for fruit tree cultivation, mulching,
irrigation, and fertilization influence the water and nutrient supply
to the plant, which can in turn affect the nutritional quality of the
harvested plant part.
 The effect of fertilizers on the vitamin content of plants is less
important than are the effects of genotype and climatic conditions.
The effects of mineral and elemental uptake from fertilizers by
plants are, however, significant and variable.
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13. Cont…
 Cultural practices such as pruning and thinning determine the crop
load and fruit size, which can in turn influence the nutritional
composition of fruit.
 The use of pesticides and growth regulators does not directly
influence fruit composition but may indirectly affect it due to
delayed or accelerated fruit maturity.
 Effective pre-harvest disease control greatly influences disease
incidence and severity during post-harvest handling of fruits and
vegetables
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14. Cont…
D. Maturity at Harvest
 Maturity at harvest is the most important determinant of
storage-life and final fruit quality.
 Immature fruit are highly susceptible to shriveling and
mechanical damage, and are of inferior flavor quality
when ripe.
 Overripe fruit are likely to become soft and mealy with
insipid flavor soon after harvest.
 Fruit picked either prematurely or too late, are more
susceptible to post-harvest physiological disorders than
are fruit picked at the proper stage of maturity.
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15. Maturity
The maturity of harvested perishable commodities has an important
bearing on their storage life and quality
meaning and measurement of maturity is, therefore, central to post
harvest handling of these perishable commodities
Maturity - stage at which a commodity has reached a sufficient stage
of development
its quality should be at least the minimum acceptable to the ultimate
consumer
Horticultural maturity when it possesses the prerequisites for
utilization by consumers for a particular purpose.
Physiological Maturity stage when maximum growth and
maturation has taken place. 91

16. Maturity Indices
Maturity indices give an indication of the stage of
development or maturation of a crop and are determined on
the basis of some characteristic known to change as the
crop matures
Both subjective and objective criteria are used for
assessing the maturity indices of fruits
Subjective Criteria Maturity
Skin Or Flesh Colour: Complete loss of green color with
the development of yellow, red or purple pigments occurs
with many commodities in particular stone fruits. Ground
color is not, however, entirely reliable as it is influenced by
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17. Cont…
Flesh Firmness: As fruit mature and ripen they soften. This
softening can be estimate subjectively by finger or thumb
pressure. A more precise objective measurement, giving a
numerical expression of flesh firmness is possible with the use
of a fruit pressure tester or penetrometer.
Size And Shape Fruit shape may, in some cases, be used to
evaluate maturity. Some cultivars, for example, become less
angular in cross section as development and maturation
progress. The fullness of the ‗cheeks‘ adjacent to the pedicel, as
in the case of mangoes and stone fruit, may be used as a guide
in assessing the maturity of mangoes. Size is generally of
limited value in assessing fruit maturity, though it is used for
fruits marketed in their early stages of development
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18. Judging mango harvest maturity by shape
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19. Cont…
Sound When Tapped The sound made when tapped by
fingers is used as an indicator of the maturity of fruits
such as melons, breadfruit and jackfruit.
Flavour (sweetness, sourness or bitterness) The
conversion of starch to sugar and loss of acidity during
maturation result in changes in flavour and can be used
as an indicator of maturity.
Time From Flowering or Planting (Calendar Date)
perennial crops grown in seasonal climates, calendar
date for harvest is a reliable guide to commercial
maturity This relies on a reproducible date for the
constant growth period time from flowering through to
maturity. 95

20. Cont…
Objective Criteria For Maturity
Chemical Measurements Measurement of the chemical
characteristics of fruits facilitates maturity determination,
particularly as these characteristics can often be related to
palatability
Iodine test. The conversion of starch to sugar during
maturation is used as the basis for assessing the maturity of
some fruits. This assessment is based on the reaction
between starch and iodine to produce a blue or purple
color. The intensity of the blue colour correlates to the level
of starch remaining in the fruit. This test can also be used to
demonstrate the disappearance of starch from the pulp of
ripening bananas. 96

21. Measurement of sugar content. Sugar content can be
directly measured by chemical means. Given the fact
that sugar is usually the major soluble solid constituent
of fruits, the total soluble solids content of extracted
fruit juice is generally used as a measure of the sugar
content and is measured with the use of a
refractometer.
Measurement of dry matter content. Changes in dry
matter content can be used as an index for fruits which
show a large increase in starch or sugar levels with
fruit maturation. Dry matter can be conveniently and
rapidly determined using a microwave or air oven to
dry the material prior to weighing.
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22. Cont…
Measurement of acidity. Acidity can be readily determined
on a sample of extracted juice through titrimetric methods.
Sugar To Acid Ratios. Given the rapidity of loss of acidity
during maturation and ripening, the sugar to acid ratio or
total soluble solids to acid ratio is often better related to the
palatability of the fruit than either sugar or acid levels alone.
pH. The pH of extracted juice can be easily measured with
the use of a pH meter
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23. Physical Measurements
Measurement of specific gravity. Specific gravity is the
relative gravity or weight of solids or liquids as compared to
pure distilled water at ambient temperature, which is considered
to have a specific gravity of one. As a fruit matures, its specific
gravity increases. In practice, the fruit is weighed in air, then in
pure water.
Fruit specific gravity = Fruit weight in air
Fruit weight in water
Specific gravity is rarely used in practice to determine time of
harvest, but could be used in cases where development of a
suitable sampling technique is possible. It is used to grade crops
according to different maturities post harvest.
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24. Harvest Systems
The harvest is the process of gathering mature crops from
the fields.
The harvest marks the end of the growing season, or the
growing cycle for a particular crop
Harvesting in general usage includes an immediate post-
harvest handling, all of the actions taken immediately after
removing the crop-cooling, sorting, cleaning, packing-up to
the point of further on farm processing, or shipping to the
wholesale or consumer market.
Harvesting can be performed by hand (product quality)
or mechanically (save time and cost minimization 10

25. Harvest timing is a critical decision, that balances the likely
weather conditions with the degree of crop maturity.
Weather conditions such as frost, rain (resulting in a "wet
harvest"), and unseasonably warm or cold periods can affect
yield and quality. An earlier harvest date may avoid damaging
conditions, but result in poorer yield and quality. Delaying
harvest may result in a better harvest, but increases the risk of
weather problems. Timing of the harvest often amounts to a
significant gamble
In many cases harvest ripeness and readiness for harvest are
used synonymously. However, it is more technically accurate
to use "ripeness" for fruits such as tomato, peach, pepper, etc.
On the other hand, in species where these changes do not occur
such as asparagus, lettuce, and beets, the term "readiness for
harvest" is preferable.
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26. Harvesting Tools of Fruit And Vegetables
Since harvesting is a labour intensive operation, not only does the
use of properly designed harvesting tools prevent undue
mechanical damage to produce but it also appreciably reduces the
cost of production of tree fruits Depending on the type of fruit or
vegetable, several devices are employed to harvest produce.
Commonly used tools for fruit and vegetable harvesting are
secateurs or knives, and hand held or pole mounted picking
shears. When fruits or vegetables are difficult to catch, such as
mangoes or avocados, a cushioning material is placed around the
tree to prevent damage to the fruit when dropping from high trees.
Harvesting bags with shoulder or waist slings can be used for fruits
with firm skins, like citrus and avocados. They are easy to carry
and leave both hands free
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30. Harvesting Containers
Harvesting containers must be easy to handle for workers
picking fruits and vegetables in the field. Many crops are
harvested into bags. Harvesting bags with shoulder or waist
slings can be used for fruits with firm skins, like citrus
fruits and avocados. These containers are made from a
variety of materials such as paper, polyethylene film,
sisal, hessian or woven polyethylene and are relatively
cheap but give little protection to the crop against handling
and transport damage. Sacks are commonly used for crops
such as potatoes, onions, cassava, and pumpkins. Other
types of field harvest containers include baskets, buckets,
carts, and plastic crates. For high risk products, woven
baskets and sacks are not recommended because of the risk
of contamination
10

31. Packing in Field & Transport to
Packinghouse
Berries picked for the fresh market are often mechanically
harvested and usually packed into shipping containers.
Careful harvesting, handling, and transporting of fruits and
vegetables to packinghouses are necessary to preserve
product quality
Polyethylene bags, Plastic field boxes, Wooden field
boxes are some of many materials used to transport from
field to packing house.
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32. Postharvest Handling of F & V
Postharvest handling is the stage of crop production
immediately following harvest, including cooling,
cleaning, sorting and packing The instant a crop is removed
from the ground, or separated from its parent plant, it
begins to deteriorate. Post-harvest treatment largely
determines final quality, whether a crop is sold for fresh
consumption, or used as an ingredient in a processed food
product
The most important goals of post-harvest handling are
keeping the product cool, to avoid moisture loss and slow
down undesirable chemical changes, and avoiding
physical damage such as bruising, to delay spoilage.
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33. Cont…
There are 3 main physical damages to fruit and vegetables
1.Impact: Injury caused either by dropping the fruit (or packed
fruits) onto a hard surface or the impact of fruit rubbing against
other fruit and are common during harvest and packing
2. Compression: it is often occurs during storage and bulk
transportation and is caused by the weight of the mass of fruits
on bottom layers. It also happens when the packed mass exceeds
the volume of the container or by the collapse of weak boxes
3. Abrasion: Superficial damage produced by any type of friction
(other fruits, packaging materials, packing belts, etc.) against
thin-skinned fruit such as pears. In onions and garlic abrasion
results in the loss of protective scales.
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34. Cont…
Reducing postharvest losses requires knowing more about
the causes and sources of losses
Simple changes in food handling practices can provide
excellent results
The 3 most important factors for reducing losses are
gentle handling, using protective containers and keeping
produce cool
People learning about potential new handling practices,
tools or postharvest technologies need information on
their costs and benefits in order to make an informed
decision 110

35. Procedures for Postharvest Handling
DUMPING: Fresh fruits should be handled with care
throughout the postharvest hand ling system in order to
minimize mechanical injuries. Dumping in water or in
flotation tanks should be used for fruits that withstand
wetting
SORTING Manual sorting is to eliminate fruit exhibiting
defects. it may also be necessary to sort the fruit into two or
more classes of maturity or ripeness (by their color and/or
firmness) before ripening or processing. Mechanical
sorters, which operate on the basis of color, soluble solids,
moisture, or fat content, may greatly reduce time and labor
requirements
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36. SIZING: Sizing can be done mechanically on the basis of
fruit dimension or by weight. It can be a major source of
physical damage to the fruit if the machines are not adequately
padded and adjusted to the minimum possible fruit drop
heights.
COOLING: Cooling is utilized to remove field heat and
lower the fresh fruit‘s and vegetables temperature to near its
optimum storage temperature. Cooling can be done using cold
water or cold air
WASHING: To clean fruit, water alone or with added
cleaning agents and/or chlorine (100-150 ppm) may be used.
If fruit is excessively dirty, a detergent may be used prior to
the sanitizing agent. The final rinse should be made with fresh,
clean water 112

37. Cont…
Ripening: Ripening before processing may be required for
certain fruits (e.g., avocado, banana, kiwifruit, mango, papaya,)
that are picked mature but unripe. Ethylene treatment can be used
to obtain faster and more uniform ripening. The optimum
temperature range for ripening is 15-25°C and, Relative humidity
should be maintained between 90% and 95%. Although 10 ppm
ethylene is sufficient to initiate ripening, a 20 to 100 ppm
concentration for at least two days for commercial application.
Adequate air circulation within the room is important by forcing
the ethylene-containing air through the fruit containers to ensure
uniform distribution of ethylene. It is also important to avoid
accumulation of CO2 above 1% in the ripening room since CO2
counteracts ethylene effects. This is by periodic air exchange or
by using hydrated lime
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38. Influence of fruit harvesting and
handling on processed quality
Procedure Error Result
Harvest timing Too early Inadequate flavor and color
development, low yield
Harvest timing Too late Incipient spoilage, low
quality
Rough harvest Fruit damaged, soiled Incipient spoilage,
contamination
Improper packing Unsanitary container Fruit contamination
Transportation Delayed/hot fruit Fruit deterioration
Rough transportation Unprotected fruit Damaged fruit
Temperature abuse Too high or low Rapid quality deterioration
Lengthy holding Fruit unprotected Rapid quality deterioration
Rough
unloading/conveying
Fruit damaged Rapid quality deterioration
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