Presses are the usual and traditional method of removing juice from fr
uit and vegetable materials. However, recently diffusion extraction, c
entrifugation, and specialized ultrafiltration techniques have been ex
plored and have been exploited commercially to a limited extent. Yield
efficiency diagrams that relate juice yields to mash feed rates provi
de a mechanism for comparing presses and other processes such as enzym
e treatments or decanter centrifuges for efficiency under a stated set
of circumstances. Diffusion extraction is capable of removing 90 to 9
4% of soluble solids from properly prepared apple slices, but the resu
lting juice is diluted with extraction water and is high in extracted
tannins. Concentration is necessary to obtain juice solids equivalency
, and the resulting juice has sour/astringent flavors that must be rem
oved with tannin absorbants to provide acceptable flavor. Currently, d
ecanter centifuges are used commercially and have provided an alternat
ive to presses under certain circumstances. When naturally colored and
flavored (unoxidized) juices are desired, the decanter provides a use
ful alternative to presses because it is easily inert gas blanketed. U
tilization of a metallic ultrafilter as a press has been patented but
has not achieved commercial utilization. The technical literature desc
ribing the application of these juice extraction juices, primarily to
apples, is reviewed extensively.