Food Science

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Angstrom

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Unit of Length. Equal to one ten-thousandth of a micron or one hundred-millionth of a centimeter

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Anisotropic

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Exhibiting different properties when tested along in different directions

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Density

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Mass per unit volume (eg. g/cm^3)

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Dextrose Equivalent (D.E.)

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An indication of the reducing-sugar content of a sweetener, calculated as dextrose and expressed as a percentage of the total dry substance.

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Dipole

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A combination of two electrically or magnetically charged particles of opposite sign which are separated by a very small distance.

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Elasticity

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The property by virtue of which a body resists and recovers from deformation produced by force.

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Energy

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Capability of doing work.

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Equivalent Weight

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Eq. wt. of an element or ion is its atomic or formula weight divided by its valence.

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Fluidity

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The reciprocal of viscosity.

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Force

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That which changes the state of rest or motion in matter. Measured by the rate of change of momentum.

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Gelatinize

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To cook starch in aqueous suspension to the point at which swelling of the granules take place, forming a viscous solution.

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Hydrolysis

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Process of splitting a molecule into smaller parts by chemical reaction with water.

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Hydrometer

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A type of calibrated, floating instrument used in determining the density of liquid sweeteners. Density is related to percent dry substances.

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Iodine Number (value)

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Grams of iodine absorbed per one hundred gram of a substance.

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Isotherm

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A line of constant temperature.

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Isobaric

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Of equal or constant pressure.

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Kinetic Energy

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The energy a body possesses as a consequence of its motion.

= 1/2 mv^2

where m=mass v=speed

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Molality

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Moles or g molecular wt. of solute in 1000 g solvent

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Molarity

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Moles or g molecular wt. of solute in 1 lit. solution

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Molecular Weight (MW)

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Sum of atomic wts. of all atoms in a molecule.

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Monochromatic

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All source radiation is exactly the same wavelength.

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Normality

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Gram MW of dissolved substance divided by the hydrogen equivalent of the substance (i.e. one gram equivalent) per liter of solution.

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Neutralization

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Reaction between hydrogen ion of an acid and the hydroxyl ion of a base producing water and salt.

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Oxidation

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Removal of electrons.

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Poise

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A unit of coefficient of viscosity, defined as the tangential force per unit area (dyne/cm^2) required to maintain unit difference in velocity (1 cm/sec) between to parallel plans separated by 1 cm of fluid.

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Polymorphism

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The ability to exist in two or more crystalline forms.

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Pressure

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Force per unit area (dynes/cm^2)

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Reduction

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Addition of electrons.

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Refraction

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The bending of a light or energy wave as it passes though a material with varying wave velocities or indexes of refraction.

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Scatter (light)

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Reflection of light from a surface in all directions in a nonuniform manner.

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Specific Gravity

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The ration of mass of a body to the mass of an equal volume of water at a specified temperature.

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Strain

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The deformation resulting from a stress measured by the ration of change to the total value of the dimension in which the change occurred.

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Stress

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The force producing or tending to produce deformation in a body measured by the force applied per unit area (dyne/cm^2)

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Vapor Pressure

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The pressure exerted when a solid or liquid is in equilibrium with its own vapor.

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Velocity

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Time rate of motion in a fixed direction.

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Wavelength

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Distance between two successive wave fronts of like phase (i.e. from peak to peak or trough to trough)q

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Weight

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Weight= Mass x Gravity Force

W= m x g

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Work

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A force is said to do work when it acts against a resistance to produce motion in a body measured as product of force and the distance the body is moved.

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True Solution

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Typically the particle size of the dispersed phase is less than or equal to 1 nm

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Colloid

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State or character of a dispersion system. Typically, colloidal particle size is 10 A to 1 um. When the particle size is > 1 um one typically obtains suspension.

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Colloid State

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Particle size intermediate between true solution and suspension. Because colloidal particles are larger and have less kinetic energy than those in true solution, they are not stable.

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Factors that stabilize food colloids are:

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1. Brownian movement of dispersed particles.
2. Like electrical charges on the dispersed particles.
3. Water of hydration around dispersed particles.

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Surface Tension

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Results of unequal forces of attraction at liquid/gas or liquid/liquid surface.

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Dew point

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Temperature to which a given amount of air must be cooled at constant pressure and constant water/vapor content in order for saturation to occur.

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Bingham Plastic

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An offset straight line relationship between shear stress and shear rate. An initial resistance (yield value) must be overcome after which flow starts and the system behaves as true Newtonian.
Ex. catsup, chocolate, butter, cheese, icings, spreads.

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Pseudoplastic

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(Shear Thining)
The substance flows more readily as it is stirred and sheared, an apparent viscosity (flow curve slope) decreases with increasing shear rate, often attaining a limiting slope. Gelled desserts and pudding are examples.

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Dilatant

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(Shear Thickening)
The substance flows less readily as it is stirred or sheared and the apparant viscosity (flow curve slope) increases with increasing shear rate, often attaining a limiting slope. Examples: concentrated cornstarch/water slurries (uncooked) and plastisols.

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Rheopectic

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Same as dilatant, but the original viscosity is restored after a period of rest. This system is time-dependent. Rheopectic behavior may be observed in beating of egg whites and in whipping cream.