Fruits and Vegetables Flashcards
(30 cards)
Describe the tissues in fruits and vegetables
The DERMAL TISSUE (skin or rind) is the protective covering of
each portion of the plant
The VASCULAR SYSTEM IS composed of two parts—the xylem and the phloem
The remainder, which constitutes much of the edible portion, is the ground system.
What is the main type of cell in fruits and vegetables and most abundant type in the ground system
what is their shape
parenchyma cell
polyhedral
What is the primary cell wall of the cell made up of
What is between the cell wall and the interior of the cell wall
complex carbohydrates
❑ Cellulose, hemicelluloses, pectic substances, and noncellulosic
polysaccharides.
Thin membrane called plasmalemma filled with protoplasm
Where are pigments and starch found in the cell?
what are the specific ones and their pigments or starch that are found within them?
Plastids;
Chloroplast- chlorophyll
Chromoplast- carotenoid
Leucoplasts- where starch is made and stored in the form of granules
what separates the protoplasm from the inside of the cell?
what contains flavor components, in addition, the flavonoid pigments (notably the anthoxanthins and anthocyanins) , 90% of cellular water
Thin membrane called TONOPLAST
VACUOLE
What is collenchyma tissue and sclerenchyma cells?
Collenchyma tissue are elongated cells such as in cellary. These cell walls are chewy and resistant to much softening when cooked
Sclerenchyma cells are woody cells that contribute a gritty texture to plant foods. They have thick cell walls containing lignin
EX. asparagus and green beans
What is cellulose vs hemicellulose
glucose polymer whose units are joined by 1,4- β- glucosidic linkages.Cellulose molecules can aggregate into fibrils of a somewhat crystalline structure
hemicellulose contains a variety of sugars unlike starch and cellulose
they have both pentoses and hexoses
Hemicelluloses, matted with pectic substances, serve as
a connection between fibrillar cellulose
An______ medium has a strong effect on hemicelluloses, and vegetables heated in cooking water to which soda is added quite quickly become _______and ______
alkaline
flaccid and mushy
What are pectic substances
member of this family of polygalacturonic acid compounds.
Protopectin, pectin, pectinic acid, and pectic acid.
Propectin and how it relates to pectins and pectin acids
water insoluble form of PECTIC SUBSTANCES OCCURRING in immature fruits and, to a lesser extent, in vegetables
As fruit ripens, some demethylation and hydrolysis occur along the protopectin molecules.
* Limited degradation produces PECTINS, shorter, methylated compound—dispersed easily in water.
* This change allows the heating of fruit juices, pectin, and sugar—which, after cooling, form pectin gels.
As additional demethylation occurs and hydrolysis continues, PECTINIC ACIDS form.Pectic acid is found in overly ripe, very soft fruits and vegetables. This pectic substance has lost the gel-forming abilities characteristic
As fruits & vegetables mature, they increase their content of
cellulose, hemicelluloses, and lignin.
Lignin is a noncarbohydrate polymer gives woody quality to plant foods
lignin is removed during fruit and veggie prep
Vegetables are much more likely than fruits to increase in lignin as
they age.
Postharvest changes
Synthesis of organic compounds halts after harvest
Most bulbs, roots, tubers & seeds become dormant whereas the fleshy tissues of fruits and vegetables usually undergo ripening after maturation and then continue to senescence.
What is senescence?
Fruits that exhibit an increase in respiratory rate just prior to
senescence are called_____fruits.
* They continue to ripen when harvested at the time that they are
horticulturally mature—but not yet ripe.
_____, _____, and
_______ are examples
of these fruits.
Accumulation of metabolic products, increase in res- piration, and some loss of moisture in plant foods after maturation.
Climacteric
Peaches, pears, and
bananas
______ causes accelerated ripening and early senescence of fruits during storage.
* Sometimes dubbed the “ripening hormone.
Ethylene gas
Many vegetables are considered more palatable when
they retain a reasonable sugar level.
❑ Rather than synthesizing starch.
❑For vegetables in which some sweetness is desired,
refrigerator storage is recommended.
In vegetables like legumes, potatoes & carrots,
starch synthesis may continue if the storage
temperature is approximately normal room
temperature or slightly warmer.
Corn & dried beans achieve some texture change
in cooking by______
Spinach and other greens are softened visibly during steaming or other heat treatment; Why does this happen?
taking up water as starch
gelatinizes
The cell walls become increasingly permeable,
causing water loss, and loss of turgor in the cells.
❑ Leaves wilt, and enough water accumulates in
the bottom of the pan to cook the greens.
What happens to pectic substances and hemicelluloses in vegetables when they are heated?
How do acid and alkaline mediums affect cooking and texture?
Pectic substances undergo chemical changes to
become more soluble than they their original form. Helps tenderize cooked vegetables.
❑Hemicelluloses also become softer as vegetables are heated.
❑Acid slows these changes during cooking.
❑ An alkaline medium greatly accelerates softening.
Calcium ions in molasses form ________and greatly delay _______.
* Dried beans have a hard outer covering that needs ________ prior to simmering.
* Salt in the soaking water makes the outer surface of beans
more ______ to water penetration.
A ___–minute boiling period prior to soaking beans is recommended to_______.
❑ To avoid possible souring during an overnight soaking. Addition of ____- to the water reduces the softening
time for cooking beans by about ______. Offset by some loss of ______
-insoluble calcium pectinates & pectates; softening
-Soaking in unsalted water
-Resistant
-2 minute; inactivate enzymes.
-soda; one-third; thiamine.
Mealy (non-waxy) vs Nonmealy potatoes when cooked texture differences
Mealy (non-waxy) potatoes slough and seem to become slightly fluffy
when cooked.
* Mealy potatoes have large, numerous starch granules, which
swell significantly during cooking.
Pectic substances in the middle lamella become more soluble—
allowing cells to begin to separate.
* Nonmealy (waxy) types hold their shape well and remain rather
compact after being cooked.
* Their cells tend to remain tightly associated
Chlorophyll
During ripening it _____
Types of pigment?
Change of color when vegetables heated? This conversion is facilitated by?
_______ make the color olive drab
decreases
Chlorophyll a, the more
abundant form in nature (blue-green)
Chlorophyll b (yellowish-green color)
First bright green as air is expelled then olive-drab by replacing magnesium with hydrogen. Presence of dilute acids released in cooking water
Pheophytins/pheophorbide
Retention of chlorophyll is favored by
Boiling vegetables without a cover.
❑ Heating the water to boiling before adding vegetables.
❑ Using a slight excess of water to dilute the acids.
❑Blanching, as a preparation for freezing enhances color
by expelling air from intercellular spaces.
❑The bright color is retained during freezing.
❑ And the subsequent boiling prior to serving.
❑Retention of chlorophyll results from shortened cooking
time and elimination of some organic acids.
❑Baking soda however bad for texture
Carotenoids are divided into two groups:
most prominent carotene is ____
most carotenoids are in then ____ configuration
ALL CAROTENOIDS ARE _______soluble
❑ Carotenes (potential vitamin A activity)
❑ Xanthophylls
β-carotene; trans
fat soluble
Flavonoids are subdivided into____ and ____. Describe characteristics of each
Group of closely related _______compounds.
anthocyanins and the anthoxanthins
Anthocyanins are highly pigmented, water-soluble
pigments that range from red to purple to blue.
❑ Contained in plant cell vacuoles.
❑Anthoxanthins are colorless or white—but may change to yellow.
phenolic, 2 phenyl rings; intermediate 5- or 6-membered ring
Anthocyanins
Most prominent ones
Anthocyanidins often form a complex with ______—to form the anthocyanin
Foods pigmented with anthocyanins must not contact
_______ instead cans should be lined with______
Pelargonidin, cyanidin, and
delphinidin (do not have sugar complexed with them)
glucose or other sugar present
iron, aluminum, tin, and copper ions
Enamel can linings prevent metallic interactions
