Benders'dictionary of nutrition and food technology

180expeller A horizontal barrel, containing a helical screw, used toextract oil from seeds or nuts.expeller cake The residue from oilseeds after most of the oil hasbeen removed by pressing; a valuable source of protein foranimal feeding.explosion puffing Technique used to create a porous structure inpartially dried, diced fruit or vegetable pieces to accelerate thedrying process, or cereal grains to produce breakfast cereals, byheating in a sealed vessel (a puffing gun) then unsealing toreduce the pressure rapidly.expression The extraction or separation of liquids from solids bypressure, especially juices from fruit and oil from olives and oilseeds. Various types of press are used; either batch or continuouspresses. Batch presses may be either a simple tank or aslatted cage in which the material is pressed; continuous pressesmay use a belt pressed between rollers, a screw expeller orfluted metal rollers.extensograph (extensometer) An instrument for measuringthe stretching strength of dough as an index of its bakingquality.extraction rate See flour, extraction rate.extremophiles Micro-organisms that can grow under extremeconditions of heat (thermophiles and extreme thermophiles,some of which live in hot springs at 100 °C), cold (psychrophiles),high concentrations of salt (halophiles), high pressureor extremes of acid or alkali.extrinsic factor See anaemia, pernicious; vitamin b 12 .extruder See extrusion.extrusion Process in which the raw materials are mixed, kneaded,sheared, shaped and extruded; essentially a screw press thatforces the product through a restricted opening. When the foodis also heated the process is termed extrusion cooking, a hightemperatureshort-time procedure.Extruders can be classified as: autogenous, in which temperatureincreases as a result of pressure and flow; isothermal, inwhich temperature is kept constant; and polytropic, operatingbetween these two extremes. Alternatively, they may be classifiedby the way in which pressure is developed: direct or positivedisplacement (ram or piston-type extruders and the intermeshingcounter-rotating twin-screw extruders) and indirect orviscous drag (roller, single screw, intermeshing co-rotating twinscrewand non-intermeshing multiple-screw extruders).extrusion cooking Ingredients are heated under pressure, thenextruded through fine pores, when the superheated water evaporatesrapidly, leaving a porous textured product.