10/21 Flashcards
milligrams of oxygen consumed per liter of sample during 5 days of incubation at 20C is _____
BOD (biological oxygen demand)
increased BOD indicates
a) increased water pollution with organic matter
b) decreased water pollution with organic matter
c) increased microorganisms in water
d) decreased microorganisms in water
e) nothinw, we just do it for fun
a) increased water pollution with organic matter
the focus is not about microorganisms - you’d do a procedure with petri plates; it’s an indicator of the pollution of organic matter present in the water sample
during yogurt making, lactic acid is produced as a result of the fermentation of ____ in milk (sugar)
lactose
color and flavor are present in very small amounts like 0.1 mg/g. what’s this in ppm? how aout 10^2g/10^6g? or 10^-4/g? what about as a percentage?
100 ppm; 0.01%
the _____ of visible light gives color to plants/animals
absorption
factors that affect pigment stability
- pH
- reactions with O2
- other factor
Changes in color are often detrimental to for _____ _____
food acceptability
name the 5 categories of pigments that are gone over in this class
- chlorophylls
- anthocyanins
- carotenoids
- meat protein-based pigments (myoglobin)
- tannins
chlorophylls are what color?
green
how does chlorophyll get converted to pheophytin? what color is pheophytin?
loss of Mg ion (often due to processing w/heat); olive brown
true or false: chlorophylls are affected by oxidation and change in pH
true
anthocyanins are responsible for ______ color(s) in food
red/blue/violet
the three-ring phenolic compound structure characterizes what group?
flavonoids
anthocyanins are water _____
soluble
true or false: anthocyanins can change color based on pH
true: anthocyanins tend to have stronger color in acidic pHs
anthocyanins can be connected to a sugar molecule. what’s this process called?
glycosylation
carotenoids are responsible for _____ color(s) in food
red, orange, yellow
carotenes are _____ soluble
fat
true or false: carotenes are saturated
false: they’re highly unsaturated
b-carotene is considered a precursor of vit ____
A; it’s a symmetrical structure containing 2 units of vitamin A.
what pigment is responsible for the red color in tomatoes and red carrots?
lycopene
what is the pigment responsible for the darker yellow associated with egg yolks, but is also present in leafy greens
lutein (usually this is associated with egg’s being “organic”) - it can just be incorporated into the feed of the chicken to make it seem nice
what class of pigments is responsible for the pinkish color in salmon, shrimp, and krill?
carotenoids
why do farmed salmon have more grayish flesh?
they don’t eat as much shrimp and krill
what color is used to color cheese? where does it come from?
annatto; extracted from seeds of a shrub that contains bixin and norbixin
what pigment is found in the crocus stamen
saffron. it’s $$$$$
Beta carotene is a precursor for vitamin A. One mole of beta carotene produces _____moles of vitamin A
2
phytochemicals serve as _____ in plants and protect plants from ___________ _____
antioxidants; light-induced damage
why do pigments in groups A-C have such good antioxidant functionality?
they already have delocalized electrons as absorbers of light
what’s the metal center of myoglobin?
iron
myoglobin is a _____ color in the Fe2+ state
bright red
what oxidation state of myoglobin is associated with fresh meat?
Fe2+
myoglobin is a _____ color in the Fe3+ state
purple
if CO is bound to the iron center of myoglobin, the resulting color is; this keeps the meat color for how long?
cherry red; a year - but this is considered food fraud in canada, but not the states
cured meats obtain its color due to the binding of _____
nitric oxide
true or false: the color of meat is determined by the oxidative state of the iron atom within the heme group
true
the structure of tannins can be described as
polyphenolic
tannins are responsible for what color in food products
brownish
what 5 tastes does our tongue have
sweet, salty, bitter, sour, and umami
umami is due to the presence of receptors for _____ in the tongue
glutamate
what type of volatile organic compound contribute to aroma?
- short-chain FAs
- alcohols
- aldehydes
- ketones
- sulfur-containing compounds
what compound is the major contributor to aroma in bulb veggies?
sulfur-containing compounds
what compound is responsible for the banana’s aroma?
isopentyl acetate
what compound is responsible vanilla’s flavor?
vanillin
essential oils are made up largely of _____ (class name)
terpenes
essential oils are composed of _____, _____ molecules (physico chemical properties)
volatile hydrophobic
examples of terpenes include
…. (look at slides)
what lab method can be used to extract essential oils?
steam distillation
what reactions are famous for producing flavors?
maillard, caramellization
Limonene is the essential oil responsible for the flavor of
a) lemon
b) lime
c) orange
d) graperfruit
b) lime
lol
