Fruit and Veg divided into 2 groups according to their respiratory behaviour.
Climacteric fruit - 'fleshy' fruit that show a rapid rise in rate of respiration after harvesting.
Leads to ripening and the senescence of the fruit.Eg. Banana, Mango, Pear and Avocado
Stick in Picture of Graph
Non-Climatic Fruits and most veg show no rapid increase in respiartion and changes in ripening.
Maturation is gradual.
Eg. Citrus Fruits, Pineapple, Fig, grapes and veg.
Some show a shallow peak.
Fruits that dont show climacteric keep well for long periods under normal conditions.
Changes during storage and ripening (1)
Respiration slows down temp of environemnt, delaying the ripening and senescence.
Chilling some fruit (tropical) may cause damage.
Below 13C some enzymes systems are inhibited while other continue causing the accumulation of toxic intermediate products - discolouration, flavour and texture - rots and bacterial decay.
Controlled atmosphere storage (CA/MO) MAP - Modified atmosphere within packaging films.
Slow respiartion and delay ripeneing. O2 level lowered or CO2 level can increase.
Too high CO2 or too low O2 - anaerobic respiration - accumulation of damaging toxic compounds.
Blended gas cylinders are fed into chamber and air is removed. Good temp control for storing fruits and veg.
Excess CO2 is removed by 'Scrubbing' with sodium hydroxide which absorbs gas
Changes during storage and ripening (2)
Presence of ethylene
Ethylene acts as a plant hormone and stimulates the ripening process.
Etheylene is produced in the fruit at the start of climacteric process, from the amino acid methionine.
Added externally to cause ripening.
Unripe fruit ripens rapidly when stored withj already ripe fruit.
CA with pressure reduced (lowering O2) and causing ethylene to diffuse out of fruit - delaying ripening.
Very expensize and difficult to perfect.
Storage temperatures for tropical products
To be able to state storage temperatures for tropical fruit and to describe the impact of storage below these temperatures
Temperature decreases = Respiration slows down = Ripening and senescene are delayed
Below 13C some enzyme syatems are inhibited in tropical fruits.
This causes accumulation of toxic intermediate products.
Leds to discolouration, flavour and texture change in the fruit - rots and bacterial decay.
Bananas irreversibly damaged if kept below 10C for more than a few hours.