Method Water Vapor Permeability

Oxygen and water vapor have obvious influence on active substance of food, pharmaceuticals and some cosmetics, which make chemical property of these products unstable. Therefore, commercial packaging usually raises demand on barrier property of specimen materials. At present, the fundamental method of water vapor permeability testing-gravimetric method is provoking criticism in terms of its test efficiency and test repeatability, etc. The expansibility of gravimetric method and whether gravimetric method will be replaced have become the focus of concern. This article presents a systematic analysis of test principle, present situation and prospect of gravimetric method.

Processing Maple Syrup with a Vapor Compression Distiller

A test of vapor compression distillers for processing maple syrup revealed that: (1) vapor compression equipment tested evaporated 1 pound of water with .047 pounds of steam equivalent (electrical energy); open-pan evaporators of similar capacity required 1.5 pounds of steam equivalent (oil energy) to produce 1 pound of water; (2) vapor compression evaporation produced a syrup equal in quality to that from a conventional open-pan evaporation plant; and (3) a central plant prodrucing 8,000 gallons of syrup per year should yield a return of 16 percent on investment. Increasing annual product output should increase the return on investment.