Pin mill

High-speed hammer or pin mills result in some selective grinding. Such mills combined with air classification can produce fractions with controlled protein content. An example of such a combination is a Bauer hurricane hammer mill combined with the Alpine Mikroplex superfine classifier. Flour with different protein content is needed for... 

Starch content of field peas (Pisum sativum L., cv. Trapper) ranges from 43.7 to 48% and, after being subjected to pin milling and air classification, produces a flour containing 78% starch (9,12,13). 

The composition of protein and starch fractions produced from pin milling and air classification are related to a number of variables variability in composition of field pea cultivars, number of passes through pin mill and air classifier, vane settings and protein content of peas, and seed moisture (5,9,23,31). 

Protein content of field peas is negatively correlated with lipid, cell wall material (CWM), sugar, and ash content and positively correlated with starch separation efficiency and protein separation efficiency in air classification of pea flour. The lower separation efficiency of low protein peas may be due to their high lipid and CWM content which makes disintegration of seeds and separation into protein and starch particles by pin milling difficult. It is suggested that peas with a specific protein content should be used in order to control the protein and starch fraction contents (18). 

The field pea (Pisum sativum) and small fababean (Vicia faba minor) were pin milled and air classified into protein and starch fractions or, alternately, the protein, starch and fiber were extracted by an aqueous alkali procedure. 

Dry Process. Ten kg each of the ground field pea and fababean were passed through an Alpine Pin Mill model 250 CW (Alpine American Corp., Natick, MA) (Figure 1). Two passes through the mill reduced the particle size to less than 325-mesh. The pin-milled flours were then fractionated into light and dense particles by a single pass through the Alpine Air Classifier Type 132 MP at a cut point of 15 microns (800-mesh) diameter between the two fractions (9 ), followed by a reclassification of the dense fraction (20). The two protein fractions were combined. 

Figure 1. Flow diagram for pin milling and air classification of field pea and fababean into protein and starch fractions.

Like NSI, the oil absorption capacities of the legume flours were decreased by pin milling, and the protein fractions were more functional in this parameter than were the starch fractions... 

Pin milling alone improved one functional property, oil emulsification (Table III). The pin-milled flours, protein fractions and proteinates gave oil emulsification values of 70.0-79.0% compared to values of less than 18.0% for starch products. 

The proportion of the legume flours which gelled when heated in a closed container increased from about 60 to 80% as a result of pin milling (Table IV). Also, most of the protein and starch fractions from field pea gelled under these conditions but a portion of fababean fractions remained as a pourable slurry. The proteinate and refined starch gave very firm gels. 

Product Colours. Both legume flours showed creamy-yellow colours under the Hunter Color Difference Meter but fababean flour was also slightly greenish (Table V). Pin milling improved the lightness of the flour and this colour was retained by the protein and starch fractions at the expense of the yellow values. The proteinates were light brown in appearance whereas the refined starches were essentially white. The refined fiber retained only a light shade of yellow as compared to the other products. 

Dry beans (Phaseolus vulgaris), represented by the commercial classes of navy, pinto and black were used to produce flour fractions at the Food Protein Research and Development Center, Texas A M University. Beans were dry-roasted under selected process conditions in a gas fired solid-to-solid heat exchanger, dehulled by air aspiration, pin-milled and air-classified to obtain four flour fractions. These fractions included whole, hulls, high protein, and high starch flours. 

Other coarse crushers Hammer mill Single roll crusher Pin mill Symons disc crusher Griffin mill Ring roller mill (Lopulco) Ball mill Tube mill Hardinge mill Babcock mill... 

The Alpine pin disc mill shown in Figure 2.11 is a form of pin mill and consists of two vertical steel plates with horizontal projections on their near faces. One disc may be stationary whilst the other disc is rotated at high speed sometimes, the two discs may be rotated in opposite directions. The material is gravity fed in through a hopper or air conveyed to the centre of the discs, and is thrown outwards by centrifugal action and broken against of the projections before it is discharged to the outer body of the mill and... 

Figure 2.11. Alpine pin mill with both discs and sets of pins rotating...

Solid-State Reactions of Iron Compounds. Black iron oxides obtained from the Laux process (see below) or other processes may be calcined in rotary kilns with an oxidizing atmosphere under countercurrent flow to produce a wide range of different red colors, depending on the starting material. The pigments are ground to the desired particle size in pendular mills, pin mills, or jet mills, depending on their hardness and intended use. 

Flour and feed meal roller, attrition, hammer, and pin mills... 

Vasanthan and Bhatty (1995) reported the use of pin milling and air classification as a technique for preconcentrating starch prior to wet isolation (Fig. E2.1.1, route D). Air classi-... 

Vasanthan, T. and Bhatty. R.S. 1995. Starch purification after pin milling and air classification of waxy, normal, and high amylose barleys. Cereal Chem. 72 379-384. 

Flour obtained through pin-milling tends to become stratified with differing levels of ffglucan when placed in a bucket. 

Pineapple oil, peel-oil content and aldehyde composition, see also Citrus oils Pin milling, starch isolation, 673, 677 Pipetting technique, 754-755 PL. see Pectic lyase... 

Size (P-m) Hammer Mill Universal and Pin Mill Jet Mill Jet Mills with Internal Classifier Media Mills Toothed Rotor- Stator Colloid Mill... 

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