Adv. Food Science EXAM 1

know: diagram of a parenchyma cell

pg. 128 of the textbook

dermal system

protective covering of the fruit or vegetable

-epidermal (outer) and peridermal

epidermal system

composed of epidermal cells

-thin layer of cell min the evaporation of moisture

periderm

outer protective covering

-cork-like (potato)

vascular system

contains the xylem and the phloem

xylem

Transports water

phloem

moves organic matter

ground system

editable portion of the fruit or veggie

-SPECIFICALLY: the parenchymal cells (FLESH)

collenchyma and sclerenchyma cells

cell support structure (supportive tissues)

collencyma cells

-stringy, fibrous

Ex. Celery

resistant to heat softening

sclerenchyma cells

woody

Ex. asparagus

Parenchyma cell:

middle lamella

holds the cells in a fixed position

-made up mostly of pectic substances

Parenchyma cell:

cell wall

made up of complex carbs., cellulose, hemicellulose and pectic substances

Parenchyma cell:

plasmalemma

membrane located b/t the cell wall and the interior of the cell wall

Parenchyma cell:

protoplasm

located within the plasmalemma

Parenchyma cell:

Plastids

where pigments and the storage of starch is found

3 plastids

1) chloroplasts- where chlorophyll is found (green)

2) chromoplasts- where the keratinoid are found

3) leucoplasts- starch is formed and stored

Parenchyma cell:

vacuole

house the flavor components

Ex. sugar, acids, etc.

- contain flavonoids

-where 80-90% of the water is held

cellulose

a structural component of a fruit or veg

-glucose polymer with 1,4 beta--glucosidic bonds (makes in indigestible by humans)

-most abundant

hemicellulose

structural component of fruit and veg as well

-when adding baking soda, it results in a mushy texture bc it destroys the cell wall

pectic substances

located in the middle lamella-- between cells

-cementing the cells together

- a group of polysaccharides

-undergoes changes along with the plant

pectic substances include...

protopectin, pectin, pectinic acid, and pectic acid

-undergo changes as the plant matures; often are textural

protopectin

-insoluble in water

-does NOT form a gel

-found in unripened fruit

pectinic acid

-forms when a fruit mature

-forms a gel and a little sugar

-jellies and jams with people who have DM

pectic acid

-found in overly ripe fruits

-water soluble

-does NOT form a gel

lignin

woody texture found in over-ripe f and v

-causes hardness

Ex. okra and asparagus

as vegetables mature....

the content of hemicellulose, cellulose, lignin increase

Fruit as it matures, goes from ______-> ripe --> _____

hard --> ripe --> mushy

-undergo hydrolytic reactions that increase enzyme activity that cause textural changes

bulbs, seeds, tubers, and roots becomes dormant during....

storage

fleshy fruits and vegs. undergo ripening after maturation and continue to a process called...

senescence

Senescence

accumulation of metabolic products

-results in increase respiration, loss of moisture (after maturation)

rate of respiration is directly related to...

the perishable nature of F and V

what can decrease the respiration rate of F and V?

refrigeration

resp rate varies with the state of...

maturity and ripening of many fruits

-the rate increases right before full ripening occurs (called climacteric phase)

climacteric fruit

a F that continues to ripen after it is harvested

Ex. bananas, peaches, tomato, pears

F that does NOT ripen after pricked are called...

non-climacteric

Ex. grapes,

2 starch structures

1. amylose

2. amylopectin

amylose

1,4 beta--glucosidic bonds

(very branched)

amylopectin

1,6 alpha-- glucosidic

1,4 alpha-- glucosidic

corn starch has __-__% amylose and the rest amylopectin

24-28% amylose

potato starch has __-__% amylose and the rest amylopectin

20-23% amylose

tapioca has __-__% amylose and the rest amylopectin

17-21%

starches are used mostly for _______

thickening

the starch is deposited in an orderly fashion; the amylose and amylopectin are made in....

the leucoplast in the cytoplasm of the cell

amylopectin and amylose is held together by...

H bonds

birefringence pattern

only found in raw starch

-once heat is added, the Maltese cross is destroyed

gelatinization

physical change where water must be present with heat

dextrinization

a chemical change prompted by only heat

-browning the flour w/ heat

starch will gelatinize between

...

pasting

occurs when the starch mixture is continued to be heated beyond gelatinization

____________ can determine the thickening of starches

temperature

types of starches

potato, wheat, and corn starch

potato starch: _______ effective thickener

wheat starch: _______ effective thickener

cornstarch: ________ thickening agent

most

least

excellent

sugar's effect on starch

both are hydroscopic (water loving, so they compete for water

-this delays gelatinization

-this raises the temp of where gel. will occur

-end result: decreased viscosity (flow) and a soft gel

acid's effect on starch

ex. lemon juice

combination of acid and heat creates a hydrolytic reaction that breaks down the molecule into small or fragmented molecules

(breaks down amylose and amylopectin in small pieces)

-thinning of the solution

-the less time heat in applied, the less thin the solution will be

the acid should be added __________ gelatinization occurs

after

Fat's effect on starch

ex. butter

the temperature of gel. and viscosity is reduced

as a gel. mixture cools, a ______ is formed

gel

hydrogen bonds between amylose molecules

as they bond, they trap water

looks like this: #

Syneresis

Watery liquid that leaks from a custard as it is cut and served or as it sits and ages. It is safe to eat.

-when you cut into a pie and it "weaps"

proteins effect on gelation

proteins lower the temperature that gelation occurs

retrogradation

breaking of the H bonds b/t amylose that hold the gel together; then they reform

-forms a crystalline structure (gritty)

amylopectin undergoing retrogradation

much slower

-outer branches of the molecule form H bonds with other starches in the gel

Ex. Staling of bread

-can break these bonds by applying heat; but once cooled, the crystalline structures form again

modified starches are created for...

specific applications

Modified starches:

-pre-gelatinized starches

cooked in water; dehydrated when they become swollen

Ex. instant pudding and instant potatoes

modified starches:

cold-water swelling (CWS)

starch is treated with an alcohol, then high temperature and pressure causes it to swell

Ex. instant soups (ramen noodles)

starches and retrogradation

can occur during storage

-so, cross-linked starches were developed

cross-linked starches

(chemical structure)

phosphate groups was liked to amylose and amylopectin

Ex. salad dressing

calorie control for selecting starches

for those looking for low-cal options; the best option is to choose the one with good gelling, so you use less of it, so less kcals

mouthfeel for choosing starches

amylopectin will emit a stringy texture

ex. arrowroot and tapioca

freeze-thaw stresses

the ability of a frozen, starch-thickened to be defrosted without the loss of its quality

Ex. cornstarch and wheat have bad freeze-thaw/ waxy rice flour has a good freeze-thaw

marketing stresses

food transportation; food companies use starches to help food endure temp, humidity changes

Key issues facing the food industry:

1: safety

2: Biotecnology (GMOs)

3: Health promotion

1- possible terrorist actions has accentuated the need for constant vigilance in safeguarding food.

2- developing genetically modified organisms that will have increased resistance to insects, a better amino acid profile, or other useful qualities

3- by increasing the levels of some key nutrients and other substances in food that help protect the body.

"Megafarms"

The trend in farming has been the consolidation of family farms and has resulted in "Megafarms". Big farming operations face same issues as small farmers, but on a much larger scale. They must constantly monitor many things, but must be most conscientious with animal health, human treatment of the animals they raise, and the pollution.

"green revolution"

GM plant seeds were being researched to become more resistant to drought and pests

-1960s, after the war; ongoing

estimated population (world) by 2050

9 billion

With this growth in population will come great challenges to produce a food supply that adheres to...

-Environmental controls and conservation methods

-Safe

-Nutrient-dense

-Accessible

-Available

-Acceptable to all

Natural foods

original food ingredients have been used and that artificial or chemical additives have not been included

organic foods

Plant or animal food being produced without using growth hormones, antibiotics, or petroleum-based or sewage sludge-based fertilizers

-Organically grown does not mean the food is higher in nutrient content than the same type of food that has not neem produced according to organic standards

Organic Food Production Act of 1990

the 1st act governing production and marketing of organic foods. Impact of this act did not occur until the passage of the National Organic Program (2002), administered by the Agri. Marketing Service of the US Dept. of Agriculture.

USDA organic seal requirements:

"made with organic ingredients"

-if 70% of the ingredients (by wt.) meet the requirements for being organic

-At least 95% of produce (by wt.) must not have been treated with sewage sludge-based or petroleum-based fertilizers, conventional pesticides, ionizing radiation, or bioengineering

functional foods

food and food products that provide possible health benefits beyond just the nutrients they contain

Ex. Fruits and vegetables

Neutraceutical

sometimes used to describe a functional food, but it also may be used more broadly to cover supplements and medicinal herbs

phytochemicals

compounds in foods that have biological activity that may promote health benefits beyond the effects of such nutrients as vitamins and minerals

Ex. Lycopene found in tomatoes

prebiotics

Fructooliogosaccharide and inulin---may enhance the growth of desirable intestinal microflora and possibly reduce diarrhea, urogenital infections and colon cancer

probiotics

health-promoting bacteria that are viable in the intestines. Now added to some dairy products (yogurt) to create a functional foods. The cultures used as probiotics are selected for their ability to survive the very low pH

designer foods

Manufactured food that has been created to meet consumer demand for a food that may be effective in promoting health and avoiding or minimizing the risk of certain physical problems.

Biotechnology:

-GMOs

develop plants and animals that have specific characteristics or traits. Research is aimed at developing plants that are

resistant to insects and diseases and able to produce greater yields per acre using less fertilizer or insecticide (i.e. GMOs).

Ex: Golden Rice with increased levels of vitamin A to aid in preventing blindness in Southeast Asia

Biotechnology:

-Genetic engineering

genes ID that provide he codes for making proteins that produce a desirable trait and then transferred to other organisms to develop plants or animals that continue to replicate the trait.

Bt

plant that has been modified genetically by gene splicing

-golden rice: Vit A in rice to prevent blindness

government agencies regulating biotechnology

-FDA

-USDA (oversees ag. products)

-Environment Protection Agency (EPA) (herbicides and pesticides)

Food Allergen Consumer Protection Act of 2004

Prompted by food-borne illness, legislation has been enacted to protect the health of consumers with severe food allergies

-requires that milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, and soybeans be named as ingredients

Homeland security

guards virtually all aspects of life in the US...including the food supply

Ex: tamper-proof packaging

The Strategic Partnership Program-Agroterrorism

partnership of federal agencies (FBI, FDA, USDA, DHS) collaborate with states and private industry to protect US food and commodities from terrorism.

USDA and CDC are working together to...

address diverse challenges such as inspection of facilities and sampling of products, careful examination of imported foods, and improved food security at food plants and along the supply chain

Hygroscopicity

Ability of sugars to attract and hold water to varying degrees

- high in humidity affects freshness of some baked goods (NOT candy)

solubility

amount of sugar that will go into a solution in water

-varies with temperature change

-higher in temp = higher amount of sugar that can be dissolved

what type of sugar is LEAST soluble?

Lactose crystals (ice cream)

Hydrolysis

disaccharides undergo hydrolysis when heated

-Ex: sucrose splits into glucose and fructose

hydrolysis is facilitated by...

rate of cooking and ingredients being used