Term
|
Definition
combination of materials in
foods that cannot readily be digested |
|
|
Term
|
Definition
(gums, pectic substances,
B-glucans) – digested to a limited extent |
|
|
Term
|
Definition
(cellulose, hemicellulose,
and lignin) – pass through the body
undigested |
|
|
Term
|
Definition
hydrophilic CHOs (attract and bind
water) comprised of sugars other than
glucose
Limited digestibility and very limited
caloric yield
Function as thickeners, gelling agents,
secondary emulsifiers, and fat replacers
and also contribute to increased fiber
content of foods
4 plant sources: seeds, plant exudates,
seaweed, and bacteria |
|
|
Term
| Soluble Fiber - seed gums |
|
Definition
found in guar, locust
bean
Made up of mannose (with 1,4-α-
linkages) and galactose (with 1,6-α-
linkages)
Guar gum (cold-soluble)
• Can be used as a replacement of up to
10% of flour in some baked products
Locust gum (hot-soluble) |
|
|
Term
| Soluable fiber - Plant exudates |
|
Definition
less orderly than
seed gums and often mixed with other
substances
Highly variable – contain 5-6 different
sugars and possibly acids along with
other contaminants
Therefore may present problems
during food production
Gum arabic, tragancanth, karaya |
|
|
Term
| Soluable Fiber- Seaweed Extracts |
|
Definition
Rich in galactose
• Agar – known for strong and transparent gels that
are reversible
• Caragennan – some form gels while others do not
but all have the ability to interact with proteins –
thus can stabilize milk products
• Used in ice cream making
• Algin – made up of mannose, guluronic acid, and
numerous salts
• forms both gels and films |
|
|
Term
| Soluble Fiber- Microbial Exudates |
|
Definition
polysaccharides
produced through MO fermentation
Xantham gum – from Xanthomona
campestris – very soluble, temp/pH/enzyme
stable, strong thickener, good freeze-thaw
stability – used in numerous applications
including ice creams, frozen doughs,
meringues
Other gums from MOs - Curdlan and
gellan |
|
|
Term
|
Definition
Cellulose
Hemicellulose
Lignins |
|
|
Term
| Insoluble Fiber- Cellulose |
|
Definition
Cellulose – polysaccharide
comprised of glucose molecules
joined by 1,4-β-linkages
Linkage is why it is indigestible in
humans
Can aggregate into fibrils with
somewhat crystalline structure – fairly
flat and not as kinky as amylose |
|
|
Term
Insoluble Fiber -
Hemicellulose |
|
Definition
Hemicellulose – important structural
components of cell walls
Polymers of various sugars and uronic acids
(hetergenous chemical structures)
• Xylans = xylose + glucuronic acid
• Arabans = mostly arabinose
Matted together with pectic substances in
cell walls around cellulose – contributing to
structure
Insoluble under acidic conditions but can be
solubilized under basic conditions (ie baking
soda in water) |
|
|
Term
| Insoluble Fiber - Lignins |
|
Definition
Lignins - Non-carbohydrate polymer
that contributes to structure of plant
cell walls
Large and complex, woody
Example – strawberry seeds |
|
|
Term
|
Definition
Fruits - the ripened ovary of a plant –
contains seeds
Vegetables – herbacious plant
containing an edible portion such as a
leaf, shoot, root, tuber, flower, or stem
Also – edible flowers and herbs |
|
|
Term
|
Definition
3 Tissue Systems in plants – dermal, vascular, and
ground |
|
|
Term
|
Definition
skin or rind – provides a protective coating
and reduces moisture losses. Cutin and various
waxes offer additional protection |
|
|
Term
|
Definition
transports fluids, nutrients and waste
products (xylem – moves water, phoelm – moves
nutrients in solution) |
|
|
Term
|
Definition
remaining inner portion of the plant made
up of:
• Parenchyma cells (bulk of the edible portion)
• Collenchyma and sclerenchyma cells (supporting
tissues) |
|
|
Term
|
Definition
Polyhedral – 11-20 faces depending
on plant type and species
• Intercellular spacing depends on the
shape and fit between cells – the more
space the less dense/more likely to float
• Apples - ~25% is air in intercellular spaces –
(“bobbing for apples”) vs potatoes which only
have 1% air in intercellular spaces and do not
float |
|
|
Term
Parenchyma
Cell Structures |
|
Definition
---Primary cell wall – composed of complex CHOs including
cellulose, hemicellulose, and pectic substances and other
polysaccharides
---Middle lamella – sticky substance between parenchyma
cells (primarily pectic substances) that holds cells together
---Plasmalema – a thin membrane separating the primary
cell wall from the protoplasm
---Protoplasm
-Mitochondria – involved in cell respiration and supplies
enzymes for cellular activities
- Plastids – 3 types
1. Cholorplasts – contain chlorophyll
2. Chromomasts – contain carotenoid pigments
3. Leucoplasts – where starch is formed
---Tonoplast - membrane separating the
protoplasm from the vacuole
---Vacuole – makes up a large portion of the
cell and increases in size with cell maturity
Holding ~90% of the cellular water it also
contains sugars, acids, flavors, water soluble
pigments (anthocyanins and anthoxanthins),
nutrients and proteins |
|
|
Term
Plant Foods – Tissue
Supporting Structures |
|
Definition
Collenchyma Tissue – consists of
elongated cells providing structure esp in
vegetables
Examples – celery fibrous strands, rhubarb
Sclerenchyma Tissue – woody cells that
contribute to the gritty texture of fruits
Examples – stone cells (sclerids) in pears,
strings in green beans, asparagus |
|
|
Term
Changes to Plant Cell
Structure |
|
Definition
Occur:
During maturation
Postharvest/during storage
During food preparation |
|
|
Term
Plant Foods – changes
during maturation |
|
Definition
Content of cellulose, hemicellulose,
and lignis increases with maturity
Lignins increase much more in
veggies than in fruits – contributes to
rough, woody texture of “older” plants
Pectic substances undergo changes –
fruit goes from hard to mushy |
|
|
Term
Plant Foods – changes
during postharvest/storage |
|
Definition
Ripening occurs in the fleshy portion of fruits and vegetables
due to continued respiration – bulbs, roots, tubers, and
seeds are relatively dormant during storage
Senescence occurs when the fruit or vegetable is past its
prime or overripe
Senescence – increase in respiration, accumulation of
metabolic products and loss of moisture
Respiration can be slowed by refrigeration – temperature
specific to the fruit or vegetable
Respiration can also be slowed by adjusting the level of
CO2 during storage
Enzyme levels increase – lipases, invertase, pectic
enzymes, chlorophyllase, peroxidase, cellulase,
hemicellulase
Fruits can be:
climacteric – accelerated respiration
just prior to senescence (continue to
ripen after harvesting) – ex’s:
tomatoes, pears, peaches
nonclimacteric (do not ripen after
harvesting – ex: oranges, grapes
Vegetables – non-climacteric
Respiration can be slowed by
refrigeration – temperature specific to
the fruit or vegetable
Respiration can also be slowed by
adjusting the level of CO2 during
storage
Respiration can be accelerated by the
addition of ethylene gas (ripening
hormone) |
|
|
Term
Plant Foods – changes
during preparation |
|
Definition
Starch may gelatinize – beans and legumes
Loss of turgor (rigidity) of cell walls
Loss of water from the cells
Pectic substances become more soluble
Hemicelluloses become softer with heat –
leading to softer vegetables
Calcium ions can react with pectic
substances in the middle lamela resulting in
increased rigidity
Also occurs in foods containing molasses |
|
|
