Search results
Results from the WOW.Com Content Network
The Penman equation describes evaporation (E) from an open water surface, and was developed by Howard Penman in 1948. Penman's equation requires daily mean temperature, wind speed, air pressure, and solar radiation to predict E. Simpler Hydrometeorological equations continue to be used where obtaining such data is impractical, to give comparable results within specific contexts, e.g. humid vs ...
The rate at which the consumer encounters food items per unit of food density is called the attack rate, a. The average time spent on processing a food item is called the handling time, h . Similar equations are the Monod equation for the growth of microorganisms and the Michaelis–Menten equation for the rate of enzymatic reactions.
A system may be targeted at a specific audience. Rating systems have been developed by governments, non-profit organizations, private institutions, and companies. Common methods include point systems to rank (or rate) foods based on general nutritional value or ratings for specific food attributes, such as cholesterol content. Graphics and ...
It is not enough for molecules of water to form an ice lattice at saturation pressures; they require a surface to condense on to or conglomerations of liquid water molecules of water to freeze. For these reasons, relative humidities over ice in the atmosphere can be found above 100%, meaning supersaturation has occurred.
The water in food has a tendency to evaporate, but the water vapor in the surrounding air has a tendency to condense into the food. When the two tendencies are in balance— and the air and food are stable—the air's relative humidity (expressed as a fraction instead of as a percentage) is taken to be the water activity, a w. Thus, water ...
The saturation vapor density (SVD) is the maximum density of water vapor in air at a given temperature. [1] The concept is related to saturation vapor pressure (SVP). It can be used to calculate exact quantity of water vapor in the air from a relative humidity (RH = % local air humidity measured / local total air humidity possible ) Given an RH percentage, the density of water in the air is ...
e * is the saturation water vapor pressure T is the absolute air temperature in kelvins T st is the steam-point (i.e. boiling point at 1 atm.) temperature (373.15 K) e * st is e * at the steam-point pressure (1 atm = 1013.25 hPa) Similarly, the correlation for the saturation water vapor pressure over ice is:
The moisture content of grains is an essential property in food storage. The moisture content that is safe for long-term storage is 12% for corn, sorghum, rice and wheat and 11% for soybean [ 1 ] At a constant relative humidity of air, the EMC will drop by about 0.5% for every increase of 10 °C air temperature.