Food Chem Flashcards
Why are sugars called polyhydroxy sugars?
Because sugars (carbohydrates) have a hydroxyl group and either an aldehyde or a ketone group
Sucrose (a disaccharide), also known as table sugar is composed of ____ + ____
glucose and fructose
Give examples of disaccharides
Sucrose, Lactose, Maltose (most abundant)
Also known as milk sugar
Lactose
Also known as malt sugar
Maltose
Lactose is made up of ____ + _____
glucose and galactose
Maltose is made up of ____ + _____
Glucose and glucose
What is a trisaccharide?
it is a carbohydrate composed of 3 monosaccharides
Oligosaccharides are composed of ______ monosaccharides
2 to 10
Where are the most abundant disaccharides (sucrose, lactose, maltose) found?
Sucrose - found in most fruits and veg
Lactose - found in milk and dairy products
Maltose - found in malted drinks
Monosaccharides are joined together by the ______.
Glycosidic bond/linkage
Polysaccharides can either be ______ or ______.
Homopolysaccharides or heteropolysaccharides
Give examples of Homopolysaccharides
starch and cellulose
Give examples of Heteropolysaccharides
pectins, gums
Monosaccharides are simple sugars composed of ____ carbons in a chain
3 to 7
Monosaccharides with an aldehyde group at C1 are called _____, while those with a ketone group at C2 are called ______
aldoses, ketoses
What does the R/S configuration mean, also the D/L configuration
R/S configuration, also known as the D/L configuration is used to describe the steriochemistry of sugars.
R configuration or Dextro means (+) sign
S config or Levo means (-) sign
All naturally occurring sugars have what configuration?
R configuration; naturally occurring sugars are D-sugars
Where is the -OH group located in naturally occurring sugars?
OH is located FARTHEST from the carbonyl group and at the RIGHT in a Fischer projection
TRUE or FALSE:
D-glucose is readily metabolized by the body while L-glucose is not
TRUE
What is the most abundant type of aldoses?
Glucose
a type of reaction involving water
Glucose is made from what?
reaction between homopolysaccharides
Glucose is made from the hydrolysis of starch and cellulose
identify the type of reaction involving water
Galactose is made from what?
rxn with heteropolysaccharides
Galactose is made from the hydrolysis of fruit pectins
choose which one
All monosaccharides are reducing or nonreducing sugars
All are reducing sugars
describe the config
When sucrose (table sugar) is hydrolyzed, what happens to its configuration?
config changes
Hydrolyzed sucrose will be an invert sugar which has a negative or S configuration
a type of sugar
When sucrose (table sugar) is hydrolyzed, what kind of sugar will be formed?
Sucrose that is hydroylyzed is called an invert sugar
compare
Table sugar vs. Invert sugar
invert sugar is sweeter than sucrose does not form crystals; it remains in syrup form
invert sugar is formed from the hydrolysis of table sugar while table sugar naturally occurs in sugar canes, beets
What enzyme cleaves the beta-1,4 glycosidic bond in lactose
Lactase
it’s the absence of a catalyst
What makes poeple lactose-intolerant
what makes their body not digest lactose
Lactose-intolerant people are incapable of producing lactase, so lactose cannot be absorbed and digested by their bodies
type of rxn involving water
Maltose is produced from what
It is produced from the hydrolysis of starch by the enzyme amylase
name the enzyme
Enzyme that digests starch
Amylase
name the disaccharide
____ is present in malt, germinating grains, corn syrup, and products of carbohdyrate digestion
Maltose
name the disaccharide
Used in the manufacture of hard sweets and frozen desserts
Maltose
Examples of trisaccharides
Raffinose and stachyrose
name the monosaccharide units
Raffinose is made up of ____ + ____ + ___
Glucose + Galactose + Fructose
Stachyrose is made up of ____ + ____ + ___
Galactose + Galactose + Glucose
name the homopolysaccharide
The most abundant organic compound after cellulose & main source of energy for man
Starch
Starch is composed of ____ and _____
include percentage
amylose (20%) and amylopectin (80%)
Why is the structure of amylose and amylopectin coiled?
Because of the alpha linkage
describe the characteristic of its structure
What makes cellulose water-insoluble?
Cellulose has a linear structure because of the beta linkage, meaning that only few OH groups on the surface can H-bond with water. This makes cellulose water insoluble.
Even if daghan ang OH groups, interaction comes from the surface raman
Function of cellulose in the food industry
It is used as an anti-caking agent, emulsifier, stabilizer, thickener, gelling agent, dispering agent among others
compare the two; focus on their composition
Simple vs. Complex carbohydrates
Simple carbohydrates - composed of monosaccharides; cannot be broken down into smaller sugars through hydrolysis
Complex carbohydrates - made of 2 or more simple sugars linked by a glycosidic bond
give a short description
What is a derivative of cellulose? How is it prepared?
focus on the reaction of cellulose between an acid and a base
CMC (carboxymethyl cellulose). It is prepared by reacting cellulose with an alkali and chloroacetic acid
What are the food uses of CMC?
Water retention, gelling, emulsifying, stabilizing, among others
Is composed of complex polysaccharides abundant in the green parts of terrestrial plants
Pectin
This polysaccharide is rich in **galacturonic acid **
Pectin
What are the food uses of pectin?
It is used mainly as a thickening agent, gelling agent, and stabilizing agent
Known as hydrocolloids, they are very versatile biopolymers used in the food industry as an ingredient or additive
Gums
Function of gums in the food industry
Gelling, thickening, moisture retention, emulsification, stabilization
What is the animal analog to starch?
Glycogen
Known as a polysaccharide derived from D-glucose; comes in alpha and beta structure
Glucan
Give examples of alpha-glucans
Dextran, glycogen, starch
What are examples of beta-glucans?
Cellulose, oat, barley, wheat, zymosan
They help reduce LDL cholesterol and decrease the risk of heart disease
Beta-glucan
name the sugar alcohol
Reduction of glucose yields ____, while reduction of xylose yields ____
sorbitol and xylitol
This is a general test for all sugars where a positive sign shows a purple interface
Molisch test
Lipids are soluble in organic solvents but not in ___
Water
give a characteristic
What are simple lipids?
according to acyl residue characteristics
Simple lipids are not saponifiable, meaning they cannot be broken down or hydrolozed
give a characterisic
What are acyl lipids?
They are saponifiable lipids. They also mostly contain FAs
give a characteristic
What are neutral lipids and what are they composed of?
according to polar and neutral characteristics, focus on their compositi
Neutral lipids are simple lipids mainly composed of storage TAGs and wax esters
Polar lipids are mainly composed of ____
2 things (a class of lipids)
glycolipids and phospholipids
complete the sentence
Animal fats are made up of ____ fatty acids and are usually _____
saturated and **solid at room temperature **
finish the sentence
Vegetable oils are composed of ____ fatty acids and are usually ____
unsaturated, liquid at room temperature
name the kind of oil
Known as having the highest natural source of lauric acid, composed of 90% saturated FA and about 9% unsaturated FA
Coconut oil
This is a semi-solid fat that is solid at room temp
Vegetable shortening
name how many bonds
Saturated compounds are all ____ bonded
single
name its characteristic
Unsaturated FAs are relatively ___ and consists of at least one ____
unstable, double bond
What are amino acids composed of?
focus on functional groups
carboxylic acid (COOH) groups and an amine (NH2) group
Derived proteins are compounds obtained by ____
chemical or enzymatic modifications
example is rennet-coagulated casein
Describe the process
How does coagulation occur?
focus on casein molecules in milk
It occurs when casein molecules in milk clump together and form curds
name the process
What triggers coagulation?
used for soft cheeses
Acidification
Name the enzyme which speeds up the coagulation process
used for harder cheeses
Rennet
This is made from partially hydrogenated oils (PHO) like corn, soybean, cottonseed
Vegetable shortening
Polyunsaturated FAs (PUFAs) are FAs with two or more double bonds. To be functional, they must be in _______ configuration
cis (z) configuration
name the process
This lengthens the shelf-life of fats and oils by the catalytic addition of hydrogen, thereby reducing the unsaturation
Hydrogenation
What kind of rancidity produces off-flavored products due to autoxidation (rxn occurring at nomal temperature due to contact with air)
Oxidative rancidity
The unsaturation in FAs is prone to attack by oxygen to form ____.
Peroxides
The intermediate in fat autoxidation reactions is called a ____ (very unstable, broken down to produce aldehydes, alcohols, hydrocarbons)
lipid hydroperoxide
list the mechanisms
The formation of lipid hydroperoxides can occur by one of three mechanisms: ____, _____ and _____
- free radical
- photooxidation
- enzymatic oxidation
list the steps
The free radical route is composed of three steps:
- initiation
- propagation
- termination
identify the type of rancidity
This reaction is caused by the hydrolysis of the triglycerides into their component FAs and glycerol. Reaction occurs without oxygen but favored by moisture and temperature
Hydrolytic rancidity
Formation of short-chain FAs also accelerates the reaction. Hence, hydroylytic rancidity is also ____.
think of catalysts
autocatalytic
it means that products are also catalysts
They prevent oxidative rancidity and interfere either in the initiation or propagation step in the free radical reaction
Antioxidants
An ____ is any substance that delays, retards, prevents the development of rancidity due to oxidation.
antioxidant
Metal deactivators are often combined with antioxidants to prevent metal-induced oxidation. How do metal deactivators work?
state function of the metal deactivator
They form a complex with the active metal ion to reduce the rate of the chain initiation.
give examples
Common metal deactivators
Citric acid, ascorbic acid, EDTA
Function of laccases in the beverage industry
Laccases are enzymes that are used as stabilizing and clarifying agents in juices and other beverages.
These are relatively less stable, fat-soluble vitamins
Vitamins ADEK
These vitamins are water-soluble and are more stable
Vitamin B-complexes and vitamin C (ascorbic acid)
List the Vitamin B-complexes
- B1 - thiamin
- B2 - riboflavin
- B3 - niacin
- B5 - pantothenic acid
- B6 - pyridoxine
- B7 - biotin
- B9 - folate, folic acid
- B12 - cobalamin
Cholecalciferol (Vitamin D3) is derived from ____.
Dehydrocholesterol
list the sources
Vitamin E top sources
top sources per 100 mg
- nuts and seeds
- veggies
- fruits
Vitamin K top sources
- dark leafy veggies
Vitamin C top sources
- fruits (per item)
- veggies (per half cup)
- juices (per 3/4 cup)
Vitamin BC top sources
- leafy greens
- grains
- dairy
- meat
state main functions
What are the functions of Vitamin K?
- balances bodily fluids
- helps nutrient uptake and water in cells
- helps in digestion
What are the functions of Calcium?
- both bone and teeth formation
- nerve muscle function
- supports cardiovascular health
state some of the functions
What are the functions of Iron?
- delivers O2 in the body through RBCs
- keeps levels of O2 in muscles
- regulate/support healthy growth and development
What are the functions of Zinc?
- strengthens immune system
- supports healthy growth and development
- assists in insulin production
Enumerate the macrominerals
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- Magnesium
- Sodium
- Potassium
- Phosphorus
- Sulfur
- Calcium
- Chloride
Enumerate the microminerals
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- Chromium
- Manganese
- Iron
- Copper
- Zinc
- Iodine
- Selenium
- Molybdenum
finish the sentence
All amino acids except ____ have the ____ configuration
cysteine, S
Name the essential amino acids
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- Tryptophan
- Threonine
- Histidine
- Valine
- Isoleucine
- Phenylalanine
- Methionine
- Lysine
- Leucine
Name the non-essential amino acids
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- Alanine
- Arginine
- Asparagine
- Glycine
- Glutamine
- Cysteine
- Aspartic acid
- Glutamic acid
- Tyrosine
- Proline
- Serine
TRUE or FALSE: Sweet amino acids are found mainly among the D-series while bitter amino acids are generally within the L-series
True
complete the sentence
____ are formed by binding amino acids through an ____ linkage.
Peptides, amide
Peptides with higher molecular weight are called ____.
Polypeptides
Refers to how slow or fast a reaction proceeds
Reaction rate
For an effective collision to take place there must be:
1.
2.
- enough activation energy
- proper orientation of reactant particles
What does isobaric, isochoric, isothermal, and adiabatic mean?
- constant pressure,
- constant volume,
- changes within the system, all except temp,
- heat which neither enters nor leaves the system
____ is the total heat content of the system
unit: BTU, Joules, cal
Enthalpy
Is the proportional constant between the convective heat flux and temperature gradient
unit: W/m^2 K
Heat transfer coefficient, h or U
Is the amount of heat that will be transferred by conduction through a thickness of a material
Unit: W/m K
Thermal conductivity, k
What is the unit for entropy (S)?
J/K
what law
The change in internal energy is equal to the heat added to the system minus the work done by the system
1st law of thermodynamics
Are mixtures with dispersed particles larger than solutes but small for the mixture to be heterogenous
Colloids
Colloids ARE NOT a true solution
Which of the ff. is a hydrophilic aqueous colloidal dispersion?
a. Oil
b. Protein
c. Salwater
d. Dichloromethane
b. protein
identify correct definition
What is a solute?
a. a species formed and used up; will not appear in rate law
b. the minor component, is dissolved
c. small particles suspended in solvent, not a strue solution
d. a solid catalyst in an aq soln
b. minor component
A solid sol is a ___ in ___ colloid
solid (dispersed phase) in solid (dispersed medium)
Ruby, diamond are examples of ___
solid sol
Mist and fog are examples of ____ in ____ aerosol
liquid in gas aerosol
What type of aerosol is smoke?
solid in gas aerosol
Sol (liquid sol) is ____ in ____. Examples are fruit jellies
solid in liquid
Gel is ____ while solid gel is ______
liquid in solid, solid in solid
Example of (liquid) sol are the ff. except:
a. gelatin
b. fruit jellies
c. butter
c. butter
Cheese, margarine, butter are examples of ____.
Gel
Whipped cream, which is an example of liquid foam, is ____ in _____
gas in liquid
