Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
97 Cards in this Set
- Front
- Back
|
What is Gluten made up of? |
Glutenin and gliadin(Causes celiac disease) |
|
|
What is the use of salt in meats |
Salt can increase WHC, flavor enhancer |
|
|
Define Water Activity (Aw) |
Water available for reaction, ranges from 0-1 |
|
|
Properties of Low Moisture Food |
Aw<0.25, poor solvent, unfreezable at -40C |
|
|
Properties of Intermediate Moisture Food |
Aw=0.6-0.8(15-30% Moist Content), No refrigeration needed, Less packaging protection, Dried fruits, fruit cake jelly ect… |
|
|
Properties of High Moisture Food |
· Aw>0.85 Bulk or Free Water, Freezable, solvent properties, facilitates microbial growth |
|
|
What Aw provides the maximum chemical, physical, and microbial stability |
Aw=0.2-0.4 |
|
|
What happens at Aw of 0.6-0.8 |
Growth of bacteria is inhibited but yeast and mold can still grow, can be controlled by adjusting pH, adding preservatives and heat |
|
|
How can you lower Aw? |
Increase concentration of hydrophilic solutes that bind water Decrease the moisture content(dehydration) Freeze foods |
|
|
What is the importance of Aw? (6 reasons) |
Moisture content, chemical stability/shelf life, physical stability, microbial growth, designing intermediate moisture foods, designing packaging |
|
|
Aqua Lab |
Dew point temperature of air |
|
|
How to inhibit moisture diffusion? |
Adding humectants such as glycerol, salt, sugar Use a moisture Impermeable barrier |
|
|
What is the moisture sorption isotherm? |
Relationship b/w Aw and moisture content at given temp |
|
|
What is the purpose of the moisture sorption isotherm? |
To determine how much moisture a food will gain when exposed tohumidity |
|
|
What is Hysteresis? |
Difference in moisture desorption and resorption curves |
|
|
What does increased hysteresis indicate? |
Reduced Stability |
|
|
What does decreased hysteresis indicate? |
Improved stability of stored products |
|
|
What causes hysteresis? |
Collapse of capillaries and cellular structures during desorption Possible phase change or a lower Tg |
|
|
What are some applications of hysteresis |
Oven drying-more pore collapse Freeze drying- less pore collapse (texture will be good) |
|
|
What is glass transition temperature (Tg)? |
Transition from hard/glass consistency to soft or rubber like consist ency with temp inc |
|
|
What does a greater Tg mean?(2 things) |
The higher the Tg, the higher the temperature required for transition form hard to soft consistency More Stability |
|
|
What are the two muscle fibers? |
Myosin (Thick) Actin (Thin) |
|
|
What does the WHC contribute to in meats? |
Palatability (Juiciness and tenderness) Appearence |
|
|
What is water holding capacity? |
The ability of the meat to retain water even through external press ures applied to it |
|
|
What are the different forms of water? |
Bound water-bound tightly to actin and myosin Loosely Bound-Held to bound water or by stearic effect, critical for WHC Free or capillary water- Physically entrapped within the structure bu t mainly interacts with water |
|
|
What is the iso-electric point? |
The pH at which the net charge on a protein is 0 |
|
|
What is Pale Soft Exudative? (PSE) |
It occurs in pork, is hereditary, and is detected using a Halothane sensitivity test in piglets It is caused by acute stress which causes a sudden fall in pH Results in protein denaturation and lowers the pH to close to the isoelectric point |
|
|
What is Dark Firm Dry? |
Beef disorder caused by chronic stress and a slight fall in pH |
|
|
What are the pH of meats with PSE, Normal, DFD? |
PSE-5.2 Normal-5.7 DFD- 6.2 |
|
|
What are some ingredients that can be considered for further increases in water binding? |
Proteins- Soy, Whey, caseinate, collagen Carbohydrates- Corn syrup, maltodextrins, starch Hydrocolloids: Carrageenan, xanthan gum |
|
|
What are some ways to measure WHC? |
-Drip loss -Filter paper -Centrifugal -NMR |
|
|
What does salt do to the WHC in dough? |
Reduced the WHC |
|
|
What is a farinograph? |
Tool used for measuring the shear and viscosity of a mixture of flower and water. |
|
|
What are types of commercial drying? |
Conventional dryer-heating food at 100C Vacuum dryer- Pulls water out at a lower boiling point resulting in limited food product damage |
|
|
What is freeze drying/sublimation? |
Process where solid changes directly to vapor without passing through the liquid phase |
|
|
What are the purposes of edible coating? |
-increases shelf life -Acts as barrier to moisture, O2, volatile aromas -Improves appearance -Vehicle for added ingredients |
|
|
What is the pH of meat before and after slaughter |
Before-7.2 After-5.6 |
|
|
How to detect efficacy of antimicrobial agents? |
Traditional plating technique DNA based techniques Rapid Tests ELISA |
|
|
How to assure hand hygiene? |
Washing GLO Germ testing- UV based technique |
|
|
Applications of pH in food science |
increase or decrease water capacity(food quality) change the flavor (improved taste) food safety: limit microbial growth |
|
|
Biological Value |
Proportion of absorbed protein that is retained in the body for maintenance and growth |
|
|
What are amino acids? How many are there? How do they differ? |
Protein building blocks 20 Different R side chains result in different amino acids |
|
|
What are essential amino acids? Examples? |
Amino acids that the human body cannot synthesize. Arginine Leucine Lysine |
|
|
What are non-essential amino acids? Examples? |
Amino acids that the body can synthesize Alanine Proline Glycine |
|
|
What are hydrophilic amino acids? Examples? |
Polar, water soluble amino acids uncharged: Serine Basic: Arginine Acidic: Aspartic Acid |
|
|
What are Hydrophobic acids? Examples? |
Non-polar, does not dissolve in water Aliphatic: Alanine Aromatic: Phenylalanine |
|
|
Why can BCAAs increase muscle development? |
BCAAs metabolism occur in the skeletal muscle |
|
|
What is tryptophan typically found in? what does it cause? |
Turkey Drowsiness |
|
|
What contributes to the Maillard Reaction? What does it result in? |
Amine containing amino acids high temperature or heat reducing sugar Unique flavor and color for foods |
|
|
What produces Nitric Oxide? What does Nitric Oxide produce? |
Arginine muscle dilation |
|
|
What is the average nitrogen content in protein? |
16% |
|
|
What is a Melamine? What issues were correlated with it? |
Melamine is a trimer of cyanamide that contains 66% nitrogen by mass Baby Formula scare in Us and Chocolate scare in Canada |
|
|
What is the most abundant amino acid in the nervous system? How much of gliadin does it form? |
Glutamic acid 40% |
|
|
What is MSG? What is used for? Issues correlated with it? |
Monosodium Glutamate Salt of glutamic acid and is a flavor enhancer Chinese restaurant syndrome |
|
|
What is a primary protein structure made up of?
|
A sequence of amino acids held together by peptide bonds
|
|
|
What is a secondary structure made of?
|
Sequence of amino acids linked by weak hydrogen bonds into one or two structural forms
|
|
|
What are two examples of a secondary structure?
|
Alpha helix, beta-sheet
|
|
|
Why is a beta pleated structure more stable than an alpha helix?
|
More thermal stability
|
|
|
What is a tertiary structure?
|
Spatial arrangement or 3-D structure caused by attractions between alpha helixes and beat sheets |
|
|
How is a tertiary structure stabilized?
|
By hydrogen and disulfide bonds
|
|
|
What causes the folding of a protein?
|
The thermodynamic need to bury all nonpolar surfaces in the interior of a protein and away from the water Reach thermodynamic stability |
|
|
What is a quaternary structure? What is an example?
|
It is the association of two or more sub units Hemoglobin- made of 4 subunits Contains more than one amino acid chain |
|
|
What type of structure can proline disrupt?
|
alpha-helix
|
|
|
What amino acid is does casein contain 17% of?
|
Proline
|
|
|
Is proline hydrophobic or hydrophilic?
|
Hydrophobic
|
|
|
What are the other two proteins present in milk?
|
alpha-lactalbumin beta-lactoglobuline |
|
|
how is casein soluble in milk?
|
It exists as a casein micelle
|
|
|
What are the three reasons why protein structure is important?
|
It can predict protein solubility It can give the denaturation temperature for a secondary structure Helps in the understanding of protein changes |
|
|
What is protein denaturation?
|
Phenomenon that transforms a folded structure into an unfolded structure under non-physiological conditions
|
|
|
Does protein denaturation occur quickly or slowly?
|
It occurs suddenly and completely over a narrow range of conditions and is slowly reversible if at all
|
|
|
What happens when a protein becomes denatured?
|
The unfolding of the protein forces some of the hydrophobic amino acids to the surface, where they have a higher tendency to aggregate with other proteins
|
|
|
What structures does denaturation disrupt?
|
quaternary, tertiary, and secondary
|
|
|
Why doesn't denaturation affect primary structures?
|
The primary structures contain peptide bonds which are really strong
|
|
|
What are some things that can cause denaturation?
|
Temperature/added energy Organic solvents such as alcohol change in pH Interactions of multiple types(acid & temp) |
|
|
What can you add to milk that will facilitate the making of cottage cheese?
|
You can add either acid or rennett
|
|
|
What is rennet?
|
Rennett is an enzyme that is present in a calfs stomach that helps break down casein to form cottage cheese
|
|
|
What is whey?
|
Whey is the green liquid left after cottage cheese has been seperated
|
|
|
What are whey proteins rich with?
|
BCAA, Branched carbon amino acids
|
|
|
What are some applications of protein denaturation?
|
Preparation of cottage cheese Protein purifuication-seperation of alpha-lactalbumin and beta-lactoglobulin from whey protein Protein gelation- Soy protein, Egg protein, Surimi(from fish muscle protein myosin and actin) |
|
|
What are some consequences of denaturation?
|
Loss of enzymatic activity-enzymatic browning Destruction of toxins-Trypsin inhibitor in soybean which is required for protein digestion |
|
|
What is enzymatic browning?
|
Chemical reaction in which freshly cut surface of fruits and vegetable turn brown when exposed to oxygen. Due to the reaction of polyphenol oxidase(PPO) with oxygen |
|
|
How can you limit enzymatic browning?
|
Treat w/acid Vacuum package Sulfites to inhibit actions of PPO GMO Temperature to denature |
|
|
What is a common way to denature proteins often used in industry?
|
High Pressure Processing- used to improve safety because the high pressures can damage microbial membranes and can improve tenderness
|
|
|
What is isoelectric precipitation of protein?
|
This is precipitation of a protein that occurs at the pH where the net charge of the protein is zero
|
|
|
Why does isoelectric precipitation work?
|
Similar charges cause repulsion A net 0 charge causes attraction and precipitation of protein |
|
|
What are some uses of isoelectric precipitation?
|
Isolation of proteins Purification of proteins-gelatin from collagen |
|
|
What is collagen?
|
Protein that connects muscles to the bone
|
|
|
How does SDS page or 1D electrophoresis work?
|
These work based off of molecular weight, the smaller proteins travel further down while the bigger proteins stay towards the top
|
|
|
How does 2D gel electrophoresis work?
|
It is a two step process 1. Isoelectric focusing which separates the proteins by charge (pH) 2. Goes through SDS electrophoresis which is based on molecular weight |
|
|
What is an emulsion?
|
Dispersion of droplets of one immiscible liquid with another or 2 immiscible liquids that stabilize by one liquid being forced to subdivide into small particles |
|
|
How can you stabilize an emulsion?
|
Requires the use of an emulsifier which decreases the interfacial tension between the two immiscible liquids
|
|
|
What is an emulsifier?
|
Emulsifiers are molecules that have an end like water molecule and other like oil
|
|
|
What is an example of an emulsifier and emulsion?
|
Emulsifier-Egg Yolk Emulsion-Salad dressing, mayonnaise |
|
|
What is a foam?
|
A mixture of aqueous and gas phase Proteins form a thin layer between gas and water |
|
|
What is foaming capacity of a protein?
|
Amount of interfacial area that can be created by protein Expressed as overrun or foaming power |
|
|
What are foam based fire extinguisher used for?
|
Oil fires
|
|
|
How do proteins contribute to flavor binding?
|
Proteins theirselves are flavorless but carry the tastes of the hydrophobic cells they interact with
|
