Add-back process

Granules In Japan, sweet potato granules are produced by the add-back process similar to that of potato granules. In this process, roots are peeled, steamed, crushed (moisture content 68%), dry granules added back (moisture content reduced to 35%-45%), conditioned, granulated, and flash-dried. The granules can be used in croquettes or snack foods [25]. 

Yeung et al. addressed the question of whether or not pull samples gave as good equations as samples measured on-line.47 The so-called add-back and process-stream samples were compared for statistical robustness in the equations they produced and their performance in predicting values in an on-line reaction. Materials such as biomass (optical density), protein, and RNA were measured by both techniques. 

It was found that fewer PLS factors were needed for process stream samples to yield a decent model. The correlation coefficients were stronger and the SEPs lower in every case. One example is protein add-back r2 = 0.891 using four PLS factors, whereas the process-stream samples enabled a three-factor PLS model to be generated with an r2 = 0.915. The respective SEP for each model was add-back = 4.351 process = 2.343. This paper seems to confirm the idea that samples taken during a process are more representative of that process. 

During production runs, it is necessary to maintain consistent smoke component concentrations in the drench solutions. This is generally accomplished through the add back system. In developing the amount of add back smoke to use one should multiply the amount of smoke required for a specific product in ml/kg by the kg/h of the product being processed and divide this by 1000. This will give the approximate number of litres of smoke being used per hour ... 

An important type of tandem reaction arises when both steps are conjugate additions (Michael reactions, chapter 9). The most widely used case is the conjugate addition 38 of a kinetic a eno-late from an enone 37 (chapter 11) to a second enone. The resulting enolate than adds back 39 to the first compound in a second conjugate addition. The product 41 contains a six-membered ring formed in the tandem process. 

FIGURE 31.3 Scheme of the add-back (solid back-mixing) process for manufacture of potato granules. (From Talburt, W.F., In Potato Processing, 4th ed., Talburt, W.F. and Smith, O., eds., An AVI Book by Van Nostrand Reinhold Company, Inc., New York, pp. 1-9, 1987.)... 

As shown in Scheme 11.14, the role of the acid is to protonate the OH group, thus allowing loss of water. In a subsequent step, water adds back. Therefore, oxygen transfer in this mechanism is an intermolecular process. In support, addition of varying percentages of 0-labeled water gives exactly the same percentage of incorporation in the product. 

The facility to alter the basic material to reduce its tendency to segregate is determined by the options available. In some cases, it may be possible to change the manufacturing process to produce a material of more imiform composition or with particles that are less easily separated. The product may be pre-processed to produce a more uniform particle size or to remove or change elements likely to segregate. The particles may be milled to introduce cohesive forces that resist particle separation. The addition of a small amount of moisture, other fluid or substance to increase surface tension or adhesion may also be used. In some cases, it may be economic to separate intransigent fractions by screening, to add back at a... 

Reprecipitation of reaction products is inevitable. In sandstone acidizing, the only way to minimize the problem once the acid treatment has been pumped is to return the well to production as soon as possible. The process of flowing spent add back must be initiated immediately. Shutting in an HF... 

If lighter colors than these are desired it is necessary to decolorize all the melanin in the hair in a preliminary step, and then add color back to the desired depth in a second treatment. This is known as a double-process treatment. The decolorization step consists of treating the hair with an alkaline mixture of persulfate salts and peroxide. The persulfate is added to the peroxide as a dry powder immediately before applying to the hair. Although the persulfate salts alone do not have any bleaching effect, the persulfate—peroxide mixture can remove all the melanin in the hair. Dark brown or darker hair can be lightened to a light blonde shade in about an hour. 

The rigidi d thermoplastic sheet - Tiocess combines thermoplastic sheet vacuum forming with a spray-up or cold press molding process to add a thermoset composite stmctural backing to a decorative thermoplastic skin. Large parts such as bathtubs, hot tubs, recreation vehicle components, and camper tops have been produced by this process. 

Enamines behave in much the same way as enolate ions and enter into many of the same kinds of reactions. In the Stork reaction, for example, an enamine adds to an aqQ-unsaturated carbonyl acceptor in a Michael-like process. The initial product is then hydrolyzed by aqueous acid (Section 19.8) to yield a 1,5-dicarbonyi compound. The overall reaction is thus a three-step sequence of (11 enamine formation from a ketone, (2) Michael addition to an a,j3-unsaturated carbonyl compound, and (3) enamine hydrolysis back to a ketone. 

Historically the production of titrate has been an important development in the pioneering of fermenter technology. It was shown back in 1893 by Wehmer that a fungus, Citromyces (now reclassified as a Penicilliutn spp.) would accumulate citric add in liquid culture. Wehmer in fact tried to scale up the process to an industrial level but there were two main problems. Firstly, the duration of the process under his conditions took far too long of the order of several weeks. Secondly, a problem was caused by Wehmer s incorrect belief that citric add only accumulated around neutral pH and lengthy incubation at this pH inevitably leads to contamination. 

The reaction can, however, be made preparative for (91) by a continuous distillation/siphoning process in a Soxhlet apparatus equilibrium is effected in hot propanone over solid Ba(OH)2 (as base catalyst), the equilibrium mixture [containing 2% (91)] is then siphoned off. This mixture is then distilled back on to the Ba(OH)2, but only propanone (b.p. 56°) will distil out, the 2% of 2-methyl-2-hydroxypentan-4-one ( diacetone alcohol , 91, b.p. 164°) being left behind. A second siphoning will add a further 2% equilibrium s worth of (91) to the first 2%, and more or less total conversion of (90) — (91) can thus ultimately be effected. These poor aldol reactions can, however, be accomplished very much more readily under acid catalysis. The acid promotes the formation of an ambient concentration of the enol form (93) of, for example, propanone (90), and this undergoes attack by the protonated form of a second molecule of carbonyl compound, a carbocation (94) ... 

---