Post harvest Management of Horticultural Crops (2+1)

Resipration

Respiration

Fruit Respiration
One of the major physiological and biochemical change which occur in fruits and vegetables is a change in the pattern of respiration. The respiration rate of produce is an excellent indicator of the metabolic activity of the tissue and thus is a useful guide to the potential storage life of the produce. If the respiration rate of a fruit or vegetable is measured as their O2 consumed or CO2 evolved during the course of the development, maturation, ripening and senescent period, a characteristic respiratory pattern is observed. The respiratory pattern also impacts the pattern of evolution of ethylene. Based on this pattern, fruits can be classified into ‘climacteric’ and ‘non-climacteric’. Few fruits exhibit the pronounced increase in the respiration (increase in CO2 and C2H4) coincident with the ripening, such increase in the respiration is known as respiratory climacteric, and this group of fruits is called climacteric.

Difference between climacteric and non-climacteric fruits

Climacteric Fruit (CF)	Non-climacteric Fruit(NCF)
Normally they ripen after harvest	Fruit that does not ripen after harvest. Ripen on the plant itself.
The quality of fruit changes drastically after harvest characterized by softening, change in colour and sweetness.(except in avocado, which will ripen only after detached from the plant)	The quality do not change significantly after harvest except little softening. Do not change to improve their eating characteristics
Exhibits a peak in respiration	Does not exhibit a peak
More ethylene is produced during ripening	Little / No ethylene production
Significant increase in CO2 production	No significant increase in CO2 production
Significant increase in CO2 production	Slowly
Decrease in internal oxygen concentration	More
Low concentration of ethylene 0.1-1.0 µ L/L/day is sufficient to hasten ripening	Not much response is seen to exogenous application of ethylene.
Eg - Many except in the apposite column	Eg- Bell pepper, Blackberry, Blueberry, Cacao, Cashew apple, Cherry, Citrus sp.,Carambola, Cucumber, Eggplant, Grape, Litchi, Loquat, Okra, Olives, Pea, Pineapple, Pomegranate, Pumpkin, Raspberry, Strawberry, Summer squash, Tart cherries, Tree tomato and rin & nor tomato, Watermelon


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Respiration
Respiration is a process in which stored organic materials (carbohydrates, protein, and fat) are broken down into simple end products with release of energy. Oxygen is used in this process and carbon dioxide is produced.




Oxidation of glucose generates an equal amount of CO2 for the O2 consumed, whereas oxidation of malate generate more CO2 then the O2 consumed. This ratio between the oxygen consumed and carbondioxide produced is called respiratory quotient. This relationship is important in measuring respiration by gas exchange.
The O2 concentration at which anaerobic respiration commences varies between tissues and is usually below 1 % V/V and off falvour may results from fermentation.

Respiration influences the product in following manner

• Reduced food value (energy value) for the consumer
• Reduced flavor due to loss of volatiles
• Reduced sweetness
• Reduce weight
• Important for the commodities desire dehydration
The rate of deterioration of horticultural commodities is directly proportion to the respiration rate
On the basis of their respiration rate we can classify different fruit and vegetables in following way:

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