Agricultural and Bio-Processing Lecture Notes

Flashcards covering terminology and technical specifications for crop processing, rice milling, and post-production standards.

Air-moving device (AMD)

A revolving, wheel-type, mechanical device used to move air for drying or aeration.

Aeration

Movement of air at a low rate through a product to maintain or improve product quality, where air flow rates usually do not exceed $0.08\,m^3/min/m^3$ of product.

Ambient temperature

Temperature of surrounding air.

Available heat

Quantity of heat in air that can be utilized in evaporating water from the product.

Batch

Small quantity of harvested crop put into a bin or container on a repetitive basis specifically for treatment (drying).

Bushel

A unit equivalent to $1.25\,cubic\,feet$, with the weight of grain defined by government standards (e.g., $56\,lb$ at $15.5\%\,w.b.$ for #2 corn).

Conduction

Transmission through or by means of a conductor, distinguished from convection and radiation.

Convection

Transference of heat or electricity by moving masses of matter, such as currents in gases and liquids caused by differences in density.

Cooling zone

Portion of the product mass in storage where the product temperature of the crop is falling during aeration.

Cubic meters per minute (CFM)

Volumetric measure of quantity of flow.

Curing

A form of conditioning where a chemical change occurs to prepare the crop for storage or use, as opposed to simple drying.

Dehydration

The rapid removal of moisture, usually to a very low level.

Dryer, concurrent flow

A continuous flow dryer where the product moves in the same direction as the drying air, also known as parallel flow.

Dryer, counter-flow

A continuous-flow dryer where the product moves in one direction and the drying air moves in the opposite direction.

Dryer, cross-flow

A dryer where the flow of air is transverse to the direction of the flow of the product.

Equilibrium moisture content (EMC)

The moisture content of a product when it is in equilibrium with the surrounding atmosphere.

Heat exchanger

A device used to transfer heat from one fluid stream to another without intermixing.

Joule (BTU)

A measure of quantity of heat, where one joule raises the temperature of one gram of water by $1^\circ C$.

LP-gas

A mixture of gaseous petroleum products (principally propane and butane) stored as a liquid under pressure.

Moisture content (dry basis)

Expressed as a percentage by weight of water in the product divided by dry matter.

Moisture content (wet basis)

Expressed as a percentage by weight of water in the total weight of the wet product.

Pascal (psi)

A measure of pressure or stress; assumed to be gage pressure unless specified as absolute.

Plenum

An air chamber maintained under positive or negative pressure, connected to distributing ducts in a drying or aeration system.

Relative humidity

The ratio of the weight of water vapor in a given volume of air to the maximum quantity it could hold at the same temperature, expressed as a percentage.

Static pressure

A measure of air pressure usually expressed in pascals [inches of water column (WC)].

Supplemental heat

Heat added to the atmosphere to obtain a limited temperature rise, usually less than $11^\circ C\,(20^\circ F)$, to finish drying before spoilage.

Tempering

Equalization of moisture or temperature throughout the product, or bringing it to a desired state for processing.

Time of one-half response

Time required to dry fully exposed products halfway to equilibrium.

Vaporizer

A heat exchanger in an LP-gas system that supplies heat to change liquid fuel to vapor for combustion.

Void space

The space between particles in a bulk of stored crop, usually expressed as a percentage of total volume.

Head rice grain

Milled rice with a size greater than or equal to $6/8$.

Large broken milled grain

Milled rice with a size between $3/8$ and $6/8$.

Small brokens

Milled rice with a size less than $3/8$ that will not pass through a $1.4\,mm$ perforated sieve.

Brewer’s rice

Broken rice that can pass through a $1.4\,mm$ diameter perforated sieve; also known as "binlid" or "chips."

Paddy Bulk Density

$$576\,kg/m^3$$

Angle of repose (Paddy)

$$36\,degrees$$

Calorific value of husks

Varies from $3000\,Kcal$ to $3500\,Kcal$.

Constant rate period

Period where drying takes place from the surface of the grain similar to evaporation from a free water surface.

Falling rate period

Drying period controlled largely by the movement of moisture within the material to the surface by liquid diffusion.

Heat Utilization Factor (HUF)

Numerical ratio defined as $HUF = \frac{T_1 - T_3}{T_2 - T_1}$ where $T_1$ is original dry bulb temperature, $T_2$ is temperature after heating, and $T_3$ is exhaust temperature.

Kiskisan

A metal cylinder mill popular in rural areas that uses friction to dehull paddy, with a low recovery of $50\%-60\%$.

Rubber roll mill

A friction type machine with two rubber rolls rotating in opposite directions at different speeds ($25\%$ difference) resulting in $70\%$ milling recovery.

Whitening

The process of removing the outer and sometimes inner bran layer from brown rice.

Polishing

The process of removing small bran particles sticking to the rice surface after whitening to give a shiny appearance.

Dunnage

Wood frames used on concrete floors for stacking bags of rice to prevent moisture migration.

Aflatoxin

Poisonous and carcinogenic compounds produced by Aspergillus flavus on substrates like corn, peanuts, and coconuts.

Yellow or damaged kernels

Milled rice damaged by fermentation, heat, water, insects, or mechanical means.

Purity

Percentage of palay grains free of foreign matter.

Modern Variety

Variety of rice and corn derived from recent genetic improvement or inter-breeding.

Well Milled Rice

Rice from which the hull, germ, and outer bran layers are removed, with bran streaks present on less than $15\%$ of the sample.