White crumb

The pulp is first steeped in an aqueous solution of sodium hydroxide (17 18%), which causes the fibers to swell and converts the cellulose to sodium cellulosate, commonly called alkali cellulose or white crumb. After steeping, the swollen mass is pressed to obtain a precise ratio of alkali to cellulose and then shredded to provide adequate surface area for uniform reaction in subsequent process steps. The alkali cellulose is aged under controlled conditions of time and temperature to depolymerize the cellulose by oxidation to the desired DP prior to reacting with carbon disulfide to form sodium cellulose xanthate. The xanthate, which is a yellow to orange crumb, is dissolved in dilute sodium hydroxide to yield a viscous orange-colored solution called viscose. The solution is filtered, deaerated, and ripened to the desired coagulation point (called salt index) appropriate for spinning. 

In one aging process, the shredded white crumb is transferred to steel cans, each holding the crumb from one complete steep of the batch process. The cans are covered and stored in a temperature-controlled room for a period of time calculated to give the correct DP. Aging time may vary from a few hours to 24 h or more at a temperature from 20 to 35°C. When an aging catalyst is used, cooler temperatures and shorter times are possible. 

A continuous belt xanthator (CBX) [239] is used at some facilities. In this equipment, the white crumb is fed through a vacuum gate where air is removed and then onto a conveyor belt where it forms a bed that can be several feet thick. The belt moves slowly through a chamber as the white crumb is sprayed with CS2. As there is no stirring of the reaction mass, the bed is usually dropped onto a second belt traveling in the opposite direction in the chamber. In this way, the xanthation is made more uniform. The xanthated crumb is discharged from the reactor through a sump filled with alkali. 

The sheets are shredded and the white crumbs are aged, which implies depolymerization to a molecular weight which is suitable for textile applications or tire cord. The material is then treated in closed equipment (batchwise or continuous) with carbon disulfide in order to xanthate the cellulose [Eq. (8)]. 

In-process controls for the reduction of wastewater flows and loads for emulsion crumb mbber plants include recycling of finishing line wastewaters and steam stripping of heavy monomer decanter wastewater. Recycling of finishing line wastewater occurs at nearly all emulsion crumb plants with the percent recycle depending primarily upon the desired final properties of the crumb. Approximately 75% recycle is an achievable rate, with recycle for white masterbatch crumb below this level and that for black masterbatch crumb exceeding it. 

Natural rubber can be found as a colloidal emulsion in a white, milky fluid called latex and is widely distributed in the plant kingdom. The Indians called it wood tears. It was not until 1770 that Joseph Priestly suggested the word rubber for the substance, since by rubbing on paper it could be used to erase pencil marks, instead of the previously used bread crumbs. At one time 98% of the world s natural rubber came from a tree, Hevea brasiliensis, native to the Amazon Basin of Brazil which grows to the height of 120 ft. Today most natural rubber is produced on plantations in Malaysia, Indonesia, Singapore, Thailand, and Sri Lanka. Other rubber-bearing plants... 

External Characters.—The taste and smell—whether pleasant or not, add, etc.—are observed. The crumb is also examined to ascertain if it is soft, porous, elastic, homogeneous and adherent to the crust, a lens being used to see if coloured spots or traces of mould occur in it, if it is more or less white, and if the fragments of bran present are more or less numerous. 

Good bread should have a pleasant odour and a crust which is brownish, shining, uniform and adherent to the crumb. The latter should be more or less white (according to the extent to which the offals are separated), soft, elastic, porous, homogeneous, free from spots, and of pleasant, non-add taste. 

Uses of partial-waxy and waxy wheat in Asian noodles, bread and tortillas have been reviewed.269,270,298 French bread made from double-null partial waxy wheat flour retained 1-2% more moisture in its crumb in 24 hours compared to bread from a wild type flour. French bread made from the mutant wheat had a softer crumb immediately and up to 48 hours after baking.299 Wheat noodles are made from flour and low levels of salts, so starch plays a major role in noodle quality. Flours from partial waxy wheats with —10% protein and 21-24% apparent amylose (starch basis) are favored for white salted (sodium chloride) noodles because partial waxy starch swells during cooking somewhat more than non-waxy wheat starch. For good appearing noodles, the flour should be from a white wheat low in polyphenol oxidase, and... 

Midwest Grain Products, Inc., The Effect of Modified Starches on Crumb Firming Rate of No-Time Dough White Pan Bread. Manhattan, KS American Institute of Baking 1993. 

Moreover, the bread crumb s moisture loss during seven days of storage open to the air, also did not show a consistent dramatic effect on these two tensile parameters (Chen et al. 1994) as one would expect. The same can be said about the compression parameters, which too showed little correlation with the moisture loss, which was measurable, of course. These reported findings, if indeed representative of the three tested breads (white, Canadian and whole wheat), would suggest that the initial textural changes that accompany bread staling are quite subtle and hence cannot be always manifested in the described crude mechanical parameters. An alternative explanation is that the failure to find the expected trends was mainly due to the large scatter in the experimental results that masked the true trend, if it really existed. 

Figure 13 Tall grassland (Mollisol) paleosol with thick, dark brown crumb-textured surface over a deep (79 cm) white nodular calcic horizon, over a thinner short grassland paleosols with carbonate nodules at a depth of 39 cm, in the Late Miocene (7 Ma) Ash Hollow Formation, 13 km north of Ellis, Kansas.

Wolf and Sessa (216) have advocated the use of lecithin in cake doughnut formulations at 0.5% to 1.0% (based on mix weight) to accelerate mixing of the batter. Prolonged batter mixing results in less tender crumb in the hnished product. Lecithin is also benehcial in white cakes, and others that contain only egg whites, by acting to replace the phospholipids normally coming from egg yolk in the formula. 

Kraton 101 [Shell], TM for a styrene-butadiene elastomer that requires no vulcanization, while displaying most of the properties of conventional vulcanized polymers. White, free-flowing crumb, readily soluble in a large number of commercially used solvents. 

Sizer C.E., Maga J.A. and Lorenz K. (1975) The occurrence of pyrazines in white bread crust and crumb. Lebensm. Hiss. Technol. 8, 267-9,... 

Microcellular crumbs can be used in considerable quantity along with china clay and whiting to reduce the product cost. Higher proportions of stearic acid (5-10 phr) are normally used in microcellular compounds in order to bring down the decomposition temperature of DNPT type blowing agents (see Appendix AlO). Post-cure oven stabilization of the microcellular sheets, typically at 100°C for 4 h, reduces the delayed shrinkage after cure to a minimum. 

Bread flavor. White bread During the baking process the impact substances 2-acetyl-1 -pyrroline and 2-ace-tyl-A (A )-tetrahydropyridine form in the crust, on storage their concentrations decrease rapidly. Precursors are metabolites of yeasL Also of importance are ( )-2-nonenal (see alkenals), 3-methylbutanal (see al-kanals), 2,3-butanedione, and methional. In bread crumbs, degradation products of linolic acid such as ( )- and (Z)-2-nonenaJ and ( , )- 2,4-decadienal predominate. 

Mica mI-ko [NL, fr. L, grain, crumb perhaps akin to Gk. mikros small] (1777) n. Any of a family of crystalline silicate minerals characterized physically by a perfect basal cleavage, consisting essentially of orthosilicates of aluminum and potassium. They occur naturally, mainly as the minerals muscovite (white mica), phlogopite... 

The conventional test for the purity of flour, with respect to bran contamination, is ash content. Ash is defined as the oxidized residue remaining after flour is incinerated at high temperatures. Because the ash content of bran (up to 8%) is considerably higher than that of the endosperm (0.3%), the ash content of flour is a sensitive index of bran contamination. High ash content of white flour adversely affects both its baking performance and the crumb color of bread baked from it. Therefore, flour specifications usually aim for the minimum ash content. 

Data are shown in Table 15.45 for white bread prepared with and without papain. There is a rise in the content of both free amino acids in the crumb and volatile carbonyl compounds in the crust when proteinase is used. As long as proteinases are active in a baking process, they release amino acids from flour proteins, which are then changed via Strecker degradation... 

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