food sciences exam 2- color and texture

Define color

the perception of physical attribute of food arising from a collection of sensations

how do humans perceive color?

we see the light that is reflected because certain colors are absorbed

why is broccoli green?

it absorbs white light except for the light rays that produce green

when is light visible?

380-780nm

name the three components of food color

hue, chroma, intenisity

define hue

the actual color

define chroma

clarity or purity of color

define intensity

range of lightness to darkness of color

what are chromophoretic compounds?

compounds that are structurally diverse and possess complicated chemical and physical properties

what gives beef its red color?

iron

how does slaughtering affect an animals meat color?

oxygenated myoglobin is no longer formed so there’s a shift to unoxygenated myoglobin

define oxygenation

the oxygenated myoglobin comes into contact with outside air, binding occurs and oxymyoglobin is formed

what do the natural plant pigments have in common?

they all have conjugated double bonds

what color is anthocyanin?

deep purple to orange red

where is anthocyanin found?

eggplants, red cabbage

what color is anthoxanthins?

colorless or white pigments that become yellow

where is anthoxanthin found?

cauliflower

what color are betalains?

violet red or yellow

where are betalains found?

beets

what color are carotenoids?

yellow-orange, red, yellow

where are carotenoids found?

pink grapefruit, red/yellow peppers, tomatoes

what does it mean to say that a food color molecule is easily oxidized?

a fruit or vegetable that loses color

what color are chlorophylls?

blue-green, green

where are chlorophylls found?

kale, lettuce, spinach

define food colorant

pigment used to impart color in a food or beverage

do food colorants have to be added to ingredient lists?

no because they’re considered additives

what is the difference between dyes and lakes?

dyes are water soluble chemicals and lakes are insoluble powder that forms a dispersion

what are the exempt colorants?

annatto (green), cochineal (insects)

what is food flavor?

property of a food material and the receptor mechanisms of the human body

how is flavor related to water?

flavors are hydrophilic groups (water soluble)

what is food pungency?

sensation of spicy or chemical heat in the oral cavity

what is one way to measure food pungency?

scoville heat unit

what is the scoville heat unit?

low heat chilis 200-2,500 Shu

high heat can reach 70,000 Shu

what is an example of when consumed endorphins are released and there’s pleasure in the pain?

capsaicinoids

when does a flavor that occurs naturally become a chemical additive?

whenever they are isolated, pulled out, and used as flavor compounds

what is an example of enzymes being used to produce flavor?

meat (think of a steak)

how is flavor encapsulation helpful in food processing?

it is used for convenience, stability of food and timed release

define flavor deterioration

unwanted flavor development in foods

what are examples of flavor deterioration

taints, hydrolytic rancidity, oxidative rancidity, and warm-over flavor

define food texture

perception of food structure when a food item is held by the fingers, pushed by the tongue against the palate, or chewed by the teeth

in determining texture, are subjective or objective methods used?

objective

why is objective better than subjective methods for food texture?

uses analytical equipment such as rheology

why are good texturing agents used?

to promote viscosity, increase firmness, and cause gelation

what are examples of food texturing agents?

polysaccarides, fat replacers, and sugars