1. Evaluation and Management of Quality

2. What is Good Quality
To the producer: a good quality is one that secures a maximum price in the market at a particular time of the season.
To the shipper: a good quality pear is a hard green pear that is capable of being transferred from orchard to market without bruising or ripening- the harder the better.
To the canner: good quality is a ripe but firm pears. The consumer requires a canned pear to be soft, but the pears needs to be firm enough to retain its shape undamaged during processing and subsequent market handling.
To the consumer of the fresh fruit, a good quality pear is a soft, ripe product, juicy. Skin color is also often important.

3. Quality may therefore be defined in terms of end use or “fitness” for purpose.
In this context produce quality refer to Market, Storage, Transport, Eating and / or processing.

4. Quality Criteria
The criteria of quality can be divided into external and internal factors.
Example of External: Waxing of apple, degreening of orange,
Internal Factor: juicy, Aroma, texture, sweetness,

5. Important quality criteria for consumers
1-Appearance, including size , color and shape
2-Condition and absence of defects
3-Mouthfeel or texture
4-Flavour
5-Nutritional value

6. 1-Appearance
People buy with “eyes” and learn to associate desirable quality with certain appearance. ei. size,shape, color, freshness.
Size is one of the most criteria.
Shape: abnormal shape e.g banana
Color; greening.

7. 2-Condition of defects
The condition of a commodity is a quality attribute referring to freshness, stage of senescence or ripeness.
Example: Wilted leafy vegetable, Shrivelled fruits, Skin blemishes, test,

8. 3-Mouthfeel
Mouthfeel , including texture, is the overall assessment of the feeling the food gives in the mouth. Sensation derived from the lips, tongue, walls of the mouth, teeth and even the ears.
Lips: sence the type of surface being presented (hairy and smooth).
Teeth: determining rigidity of structure (pressure,
Tongue and walls of the mouth are sensetive to the tupes of particles (e.g. whether they are soft and mushy or discrete lumps, juice).

9. 4-Flavour
Flavour is comprised of taste and aroma.
Taste is due to sensation felt on the tongue. The four main taste are: sweet, salt, acid (sour) and bitter.

10. 5-Nutritional value
Nutritional value is probably the least important consideration in determining whether a consumer purchases a commodity , since most essential nutrients can neither be seen nor taste.
Fruits and vegetables are the sol source of vitamin C in the diet of many people.

11. Postharvest Factors Influencing Quality
Many of the physiological changes that occur after harvest are essential for the desired degree of eating quality.
Climacteric fruit are picked at the mature-green and then allowed to ripen off the plant to optimum eating quality.
Avocado fruit, which will not ripen while attached to the tree.
In vegetables and non-climacteric fruit deterioation in quality can be caused by a variety of stress(1- metabolic stress, 2-transpiration, 3-mechanical injury stress and 4-microbial damage)

12. 1-Metabolic stress
Involves either normal or abnormal metabolism lead to senescence or development of physiological disorders.
i- respiration induced carbohydrate shortage in cut flowers (normal).
ii- Heat treatment-induced starch breakdown in mangoes
(abnormal). Another example, chlorophyll degradation in harvest brocoli.

13. 2-Transpiration
Transpiration and subsequent water loss also result in rapid loss quality.
Severe wilting of leafy vegetables and cut flowers and foliage can be induced by storage for a matter of hours under hot, dry conditions.
Water loss mainly affects appearance, through wilting and shrivelling, and texture such as crispness and fall rapidly Vitamin C in leafy vegetable.

14. Cuticle damage also increase water loss
3-Mechanical injury
M. injury causes loss of visual quality (e.g. cuts, tears, bruises, abrasions).
Such injury lead to an increase in the general metabolic rate (e.g. transpiration)
Cuticle damage also increase water loss

15. 4-Microbial injury
Microbial injury can be considered a “Secondary stress”
Postharvest diseases are mainly caused by fungi, some bacteria and yeast.
Where favourable environmental conditions of temperature, pH and water status for their growth previal the growth of pathogens can be extremely rapid and results in extensive losses.

16. Some of the major handling factors that contribute to loss of quality
Harvesting
Harvesting mechanical damage can increase disease-causing microorganisms.
The inclusion of dirt from the field can aggravate this situation.
Overheat can rapidly causing deteriorate during temporary field storage.
Failure to sort and discard immature, overripe, undersized, misshapen, blemished.

17. Transport and handling
Rough handling and transport over bumpy road damages product by mechanical action.
At high temperatures produce will become overheated, especially if there is inadequate shading or cooling.
Transport on open tracks can result in sun-scorch of the exposed produce.
Serve water loss , espicially from leafy vegetables

18. Storage
Delays in placing produce in cool storage after harvest often result in rapid deterioration in quality.
Poor control of storage conditions, storage for too long and inappropriate storage condition for a particular commodity will also result in a poor quality produce.
Mixed storage of different commodities, ethylene produced by one product (ripe fruits) can promote rapid senescence of another product (leafy vegetable).
Storage at temperature too low may induce physiological disorders or chilling injury.
High humidity can encourage growth of fungi.

19. Marketing
A serious reduction in quality can occur in produce displayed for lengthy periods in retail outlets.
Major causes of quality reduction during marketing including growth (e.g. opening cut flower, sprouting onions and potato).
Water loss leading to wilting, undesirable ripening (apple) and senescence (loss of green color and yellowing of leafy vegetables under poor management of temperature and RH.
Mechanical damage associated with rough handling by staff and customers.

20. Treatment residues
Residues of pesticides and other chemicals are another important factor impinging upon postharvest quality.
Chemical such as insecticides and herbicides are often applied preharvest. Fungicides may be used both pre and postharvest to prevent rotting.
Methyl bromide may be used for insect disinfestation, especially in export trade.
All of these types of chemicals can leave residues in the commodity that not detectible by consumer and must be considered with possible health risks .

21. Determination of maturity
Physiological maturity: A particular stage in the development of a plant or plant organ.
Commercial or horticultural maturity: Timing of the harvest to meet particular market requirements. At optimal commercial maturity, produce should be either at optimum consumer quality (e.g. ripe in the case of non-climacteric fruit such as oranges) or able to achieve optimum consumer quality (e.g. at an advanced bud stage in chrysanthemum plants for Mothers Day.

22. Determination of Commercial maturity
Commercial maturity indices generally involve some expression of the stage of development (growth, maturation or ripening) and require the determination of some characteristic known to change as the plant material mature.
Many criteria for judging maturity are:
i-time from flowering or planting
ii-accumulated hear units
iii-size and shape
iv-skin or flesh color
v-light transmission or reflection
vi-flesh firmness
Vii-electerical conductance or resistance
Viii-chemical composition (starch, sugar, acid)
ix-respiratory behaviour and ethylene production
x-time to ripen

23. Calendar time (time from flowering)
For perennial crops grown seasonal more or less the same and uniform. Calendar date for harvest can be usfull.
Calendar date based for harvest generally derived from growers experience with crops in a particular environment.

24. Heat units
time from flowering to maturity may be calculated in degree days (heat units) in particular environment.
The heat units approaches is extremely helpful in planning planting, harvesting and factory management program for annual processing such as tomato, peas, corn,. Similarity for pot plant if Tb=15 °C
20-15 °C (minimum) for 1 day C for 2 days=15 °C degree days..

25. Shape and Size
Fruits shape may be used in some instances to decide maturity.e.g. some banana become less angular in cross section.
Size is generally of limit value as a maturity index in fruits, but it is widely used for many vegetable e.i. zucchini.
Size in combination with shape in ornamental such as flowering and foliage pot plants.

26. Electrical characteristics
Colour
The loss of green colour in fruits using colour chart. i.e. tomato.
For measuring colour using Hunter and Minolta colour
Flesh firmness
As fruit mature and ripe they soften, Using penetrometer,Maness Taylor
Electrical characteristics
Changes in the resistance as a result of changes in the concentration of dissolved electrolytes flesh during maturation.

27. Chemical measurement
Is an obvious approach to determining maturity,i.e. weetness, sourness.
Starch
Sugar
TSS
Acid pH