FRUITS 1 Flashcards
what does growing fruit in middle of city help with
shelf life because less transportation
what are fruits
edible part of a plant with seed that grows
from a flower
how are fruits classified
by part of flower they develop from
whats a simple fruit
develop from one flower; pomes and drupes
whats drupe
fleshy, thin, seed enclosed in pit; date, cherry, coconut
whats a pome
thick flesh with seed in core; like apple
what do the seeds of stone fruit break into
hydrogen cyanide (bc of a compound called amygladin), which is a poison
whats an aggregate fruit
One flower several ovaries, like raspberry, strawberry, blackberry
whats mulptlie fruit
develop from cluster of several
flowers; several flowers, several ovaries e.g., Pineapples, figs
what are botanical fruits?
fruits that are normally treated like vegetables, like tomatoes, squash, okra, peppers, cucumbers
what is rhubarb
vegetable usually treated as fruit
how are fruits similar to vegetables
similar cell structure and pigments
describe acidity of fruits
Most fruits have pH < 5.0, Acidity affects flavor
* Range from very acidic (lemons and limes: pH ~2) to mildly acidic (cucumbers and squash: pH ~5)
what do organic acids contribute to
tartness
what are the major organic acids
citric acid and malic acid
what makes up citric acid
citrus fruits, berries, and tropical fruits
what contains malic acid
drupes and pomes
what are the three other kinds of organic acids
- Tartaric acid (grapes)
- Oxalic acid (rhubarb)
- Benzoic acid (cranberries)
what does pectin act as
cement between cell walls, contribute to
structure and firmness; contains several polysaccahrides; Water-soluble, forms gel
what does all pectin contain
methyl pectate: chain of repeating
galacturonic acid units – responsible for gelling
how does pectin change during ripening
Protopectin (immature fruit, no gel) -> pectin (ripe fruit, gels) -> pectic acid(overripe, no gel)
whats protopectin
Large, insoluble molecule, cannot form gel
what do the molecules in pectin do
Linear molecules form a net-like structure that is able to trap water
what happens as fruit overripens
enzymes convert pectin to pectic
acid, which Cannot form gel
what enzymes are critical in softening of fruits
pectinase
whats the relationship between pectin degradation and softening
as one increases, so does the other
whats another method to hydrolyze pecin into pectic acid
heating; texture also becomes soft
what can contribute to gelling between pectin, protopectin, and pectic acid
Only pectin (not protopectin or pectic acid) can
contribute to gelling
what is pectin commercially used for
jelling of fruit preserves
what is pectin derived from when used commercially for jelling
from the pulp (pomace) remaining after apples are pressed for juice and the albedo (white inner rind of citrus)
what do pectic substances causes when juice is extracted
cloudiness, but can clarify with pectinases
what are tannins responsible for
browning and bruising in fruits such as
avocados, apples, bananas, peaches, etc.
what are the three things that enzymatic browning requires
- Phenolic compounds (found w/in the cell)
- Polyphenol oxidase (PPO)
- Oxygen (enters cells when fruit is cut or bruised)
what does PPO do to tannis
converts from clear to brown, but still safe to consume
why does denaturing enzymes with heat help with enzymatic browning
because Blanching destroys polyphenol oxidase (PPO), but Can cause loss of fruit texture and flavor
why does lowering pH help with enzymatic browning
because optimal pH for PPO activity is 7.0, which is why highly acidic fruits don’t brown
why does lowering temp help with enzymatic browning
Cold temp slows reaction rate (doesn’t completely inhibit)
why does coating with sugar or water help with enzymatic browning
Covering fruit with layer of sugar or syrup, or
submerging in water prevents exposure to oxygen
why does adding antioxidants help with enzymatic browning
because Antioxidants use up available oxygen
ex: Commercially used (ex: golden raisins)
why are fruits functional foods
rich in antioxidants, phytochemicals, polyphenols, vasocdialters
what do polyphenols do
Associated with decreased risk of high blood pressure, heart disease, stroke, and dementia; high levels in pomegranates and berries
