Milling products, distribution

In preparing akara from each milled product, too many large particles still remained in the 2 mm material to make a smooth paste. However, highly acceptable akara with uniform shape was produced from this material after the paste was ground to eliminate the large particles. With the 0.5 mm screen, the paste was very fluid and extremely difficult to dispense, behavior which closely resembled that exhibited by the commercial cowpea flour. Akara prepared from the 0.5 mm material was also extremely distorted. Of the three screen sizes compared, the 1.0 mm screen produced the most desirable particle size distribution although the paste produced from the 1.0 mm material was somewhat more fluid than desired, it appeared that adjustments could be made in hydration of the meal to achieve an appropriate batter viscosity. 

The Mills-Nixon hypothesis that small ring annelation on benzene would induce bond fixation (bond alternation) by trapping out one Kekul6 tautomer is a casualty of early twentieth century structural chemistry. Due to a lack of direct methods for analyzing molecular structure, structural postulates of that time were often supported by an analysis of product distributions. An experimental observable such as product selectivity or isomer count was correlated to an unobservable structural feature derived on the basis of a chemical model. Classical successes of this method are van t Hoff s proof of the tetrahedral carbon atom and Fischer s proof for the configuration of sugars. In the case of Mills and Nixon, however, the paradigm broke down. 

Figure 8 Distribution of milling products by value and yield (area denotes summation of product value).

FIO. 20-13 Example of a Gates-Gaudin-Schumann plot of mill-product-size distribution. 

I = i(dentity matrix, which has ones on (diagonal, zeros elsewhere M = mill matrix, which transforms mill-fee(d-size distribution into mill-product-size distribution... 

Co-milling polypropylene and zeolite Y was carried out by Audisio and co-workers. The product distributions as a function of carbon number at 673 K are reproduced in Figure 6 for NaY, HY and rare earth Y (REY, 10.7% of rare earth oxides) and compared with those observed for thermal degradation and in the presence of silica-alumina (also reproduced above in Figure 4). The product distributions for HY and REY were very similar, while a significantly lower fraction of C5-C11 products was formed when NaY was used. A detailed analysis of the products over HY and REY revealed that a significant amount of isomerization had occurred and olefins were formed in large yields. 

The basic magnesium carbonate appears to occur in a more favourable morphology in the natural mixture than when made synthetically. Nevertheless, it is still quite platy, existing in the milled product as plates of about 4 pm diameter and a thickness of about 0.6 pm. The huntite, unfortunately, is even more platy, having a mean diameter of about 0.5 pm and a thickness of only about 0.04 pm. Because of the presence of these two different particles, the mixture has a distinctly bimodal particle size distribution. (NB The mean sizes determined by standard particle-sizing techniques tend to be distorted by the platy nature of the particles.)... 

DMDHT-modified montmorillonite clay is supplied in an agglomerate form. The basic process involves drying and grinding the modified organoclay. Air classification is recommended to remove large particles in the milled products. A typical particle size distribution curve is shown in Figure 7.3. The mean particle size is normally in the range of 15-25 tim. Top size (99%) should be less than 60 trm. 

See also Sinfelt, 1964, and Haensel, 1965]. The isomerization step is usually intrinsically very fast, and so the first part of the reaction has exactly the above sequence similar to an earlier qualitative study by Mills et al. [1953]. Weisz and co-workers performed experiments to prove this conjecture. They made small particles of acid catalyst and small particles containing platinum. These particles were then formed into an overall pellet. They found that a certain intimacy of the two catalysts was required for appreciable conversion of / heptane into isoheptane. Particles larger than about 90 pm forced the two steps to proceed consecutively, since the intermediate unsaturates resulting from the metal site dehydrogenation step could not readily move to the acid sites for isomerization. This involves diffusion steps that will be discussed in Chapter 3. Further evidence that olefinic intermediates are involved was obtained from experiments showing that essentially similar product distributions occur with dodecane or dodecene feeds. 

The rate at which milling products deteriorate under given conditions of storage is determined by level of lipase activity and particle size distribution 01 bran. In practical terms, storage of wholemeal at very low moisture and temperature is not feasible for several reasons. However, bran and germ may be stabilised by heat-moisture treatment and this is practised commercially. The relatively high heat stability of the lipase, precludes heat-treatment of wholemeal flour, because the essential functionality of wheat proteins is destroyed by less severe conditions than those required to inactivate the lipase. 

Methods were as described elsewhere for measuring a) the Oj-uptake of aqueous suspensions of milling products b) total lipid and free ratty acids c) distribution of C-label in oxidation products from l- C linoleic acid d) conjugated oxidation products (COP). Peroxide values were obtained by a standard method. ... 

The three principal domestic uses for rice in 1988 were direct food (61%), processed food (18%), and beer (20%). The direct food use figure includes the conventional white milled rice plus specialty rice products (parboiled, precooked, aromatic, brown, and prepackaged mixes) shipped directly from the rice mills. The specialty products account for approximately one-fifth of the direct food use. Approximately two-thirds of the direct food use rice is ultimately distributed to consumers through retail outlets and one-third through food service outlets. 

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