Fruit/Veg Processing
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cell wall of young plants are thin and composed mostly of ____ and held together by ___
cellulose; pectin
with aging of plants, wall thickens and higher amount of ____ and ____
hemicellulose; lignins
colours of fruits/veg due to these pigments in chloro/chromoplasts:
anthocyanins, carotenoids, chlorophylls
fruits are good source of:
natural sugar, organic acid, flavour comps, bioactive phytochem, specific vit. and min.
grapes and strawberries are examples of ____ fruits
non-climacteric (harvest fully ripened)
apples and bananas are examples of ____ fruits
climacteric (harvest when immature)
what is senescence?
phase associated with deterioration of fruits and veg caused by aging, tissue death, loss of quality (overripe/inedible)
4 phases of postharvest changes in fruits/veg
growth, maturation, ripening, senescence
plant hormone that plays key role in ripening/senescence
ethylene
effect of ethylene on F+V?
break down chlorophyll, new pigments, acids break down, amylase degrade starch to sugar, break down pectin (soften), breakdown large organic cules to produce aroma/tastes
climacteric fruits produce ___ level of ethylene when ripening, non-climacteric produce ____ ethylene during ripening
high; no
ethylene is used as ___agent in citrus
de-greening
what is metabolic process by which cells convert energy from one chem structure to another?
respiration
in ______ little energy is reserved and there is excessive respiration, will eventually lead to metabolic collapse
leafy crops
speed of post-harvest water loss depend on ______
external vapour pressure
products with large SA to V ratio (leafy) will lose water quicker or slower than large spherical fruit?
quicker
most important microorg cause post-harvest wastage of fresh produce are _____
fungi
causes for quality deterioration for fresh produce?
fungal/bacteria growth, physiological disorders (mineral imbalance, innappropriate enviro, atm composition), phys injuries
how to maintain quality of fresh produce?
precooling (room/forced air cooling, icing, hydro cooling), prestorage (surface coatings, irradiation), controlled atm storage, packaging
coatings used in prestorage treatments?
carnuba/sugar cane wax, sugar esters, petroleum based (paraffin) wax
purpose of polymeric films?
barrier to decay spread, affect mvmt resp gases, lower O2 and raise CO2, reduce resp and extend shelf life
what is active modification?
pulling of slight vacuum in pack and then replacing atm w/ desired gas mix
what is passive modification?
atm attained thru resp of products in pack