Continuous cooker

Corn is cooked in a vat or in a continuous cooker with a certain amount of lime (calcium hydroxide), which softens the outer shell of the corn and adds some flavor of the product. 

Continuous cookers are used almost exclusively for this operation. 

Heat treatment is necessary to denature the protein and to break cell walls so that oil and water can be easily removed from animal tissues (Bimbo, 1989). The raw material is first cooked wifh water in a continuous cooker at 50-70°C. The denatured protein in stickwater may then be separated from the oil by centrifugation or removal of liquors (oil and water) by applying pressure in a screw-type continuous press in which oil can be separated by centrifugation (Lee, 1963). The separated crude oil is then used for further processing/refining. 

The basic candy-making principle is simply the boiling of sugar and the temperature to which it is cooked determines whether it will be a fondant (236° F [113.3° C]) or a toffee (300° F [148° C]). Today, candy manufacturing plants are equipped with every conceivable machine for each step in the manufacture of over 2,000 different kinds of sweets. There are continuous cookers, cooling tunnels, crystallizers, forming machines, chocolate coaters, and taffy-pulling machines. 

Much of the fish that is processed is cooked in batch or continuous cookers to coagulate the protein, and passed through a continuous screw press to remove the liquid portion. The liquid then is separated by continuous decanters... 

Cooking extmders have been studied for the Uquefaction of starch, but the high temperature inactivation of the enzymes in the extmder demands doses 5—10 times higher than under conditions in a jet cooker (69). Eor example, continuous nonpressure cooking of wheat for the production of ethanol is carried out at 85°C in two continuous stirred tank reactors (CSTR) connected in series plug-fiow tube reactors may be included if only one CSTR is used (70). 

A pressure cooker is a sealed cooking pan. Being sealed, as soon as boiling occurs, the pressure of steam within the pan increases dramatically, reaching a maximum pressure of about 6 x /A, causing the final boiling temperature to increase (see Fig. 5.12 on p. 200). Unlike other pans, the internal volume is fixed and the pressure can vary the pressure in most pans is atmospheric pressure ( p°), but the volume of the steam increases continually. 

All air cleaners worked already for several years and were operated in usual manner without any variations or make up especially for the measurements. These were carried out in a moderate weather period with ambient temperatures of 16-21°C. The samples were taken during normal continuous plant performance, that means with closed cooker. In addition, in plant A samples were taken in peak load performance, when the cooker was opened. 

The vapor pressure of a liquid dictates when a substance will boil. In fact, the boiling point of a substance is defined as the temperature at which the vapor pressure equals the external pressure. Typically, the external pressure is equal to atmospheric pressure, and we define the normal boiling point as the temperature when the vapor pressure equals 1 atmosphere. If we consider water heated on a stove, the bubbles that develop in the liquid contain water vapor that exerts a pressure at the specific vapor pressure of water at that temperature. For example, when water reaches 60°C, any bubbles that form will contain vapor at 149 mm Hg (see Table 9.4). At this pressure, and any other pressure below 760 mm Hg (1 atmosphere), the external pressure of 1 atmosphere causes the bubbles to immediately collapse. As the temperature of the water rises, the vapor pressure continually increases. At 100°C, the vapor pressure inside the bubbles finally reaches 760 mm Hg. The vapor pressure is now sufficient to allow the bubbles to rise to the surface without collapsing. At higher elevations where the external pressure is lower, liquids boil at a lower temperature. At the top of a 15,000-foot peak, water boils at approximately 85°C rather than 100°C. This increases the cooking time for items, as noted in the directions of many packaged food. If the external pressure is increased, the boiling temperature also increases. This is the concept behind a pressure cooker. The sealed cooker allows pressure to build up inside it... 

Oxidized Starches. Alkaline hypochlorite treatment introduces carboxyl and carbonyl groups, effects some depolymerization, and produces whiter (bleached) products that produce softer, clearer gels. Ammonium persulfate is used in some paper mills with continuous thermal cookers to prepare in situ bigb solids, low viscosity dispersions. Most of the hypochlorite-oxidized starch and all the ammonium persulfate-oxidized starch is used in the paper industry. The low solution viscosity and good binding and adhesive properties of these products make them especially effective in high solids, pigmented... 

Starch Liquefaction. Starch in its natural state is only degraded slowly by CC-amylases. To make the starch susceptible to enzymatic breakdown, it is necessary to gelatinize and liquefy a slurry with a 30—40% dry matter content. Gelatinization temperature depends on the type of starch (67) com is the most common source of industrial starches followed by wheat, tapioca, and potatoes. Liquefaction is achieved by adding a heat-stable a-amylase to the starch slurry. The equipment used for liquefaction may be stirred tank reactors, continuous stirred tank reactors (CSTR), or a jet cooker. Most starch processing plants liquefy the starch with a single enzyme dose in a process using a jet cooker (Fig. 9). 

Pigment and heat-stable coating adjuncts may be added to the starch slurry for processing through the cooker jet or added to the dilution water. It is thus possible to obtain complete size-press formulations or low solids pigmented coatings in a continuous and on-demand fashion. The specific heat of the additives needs to be considered in the thermal balance for the system. 

Large-scale plants work continuously. A continuous dissolver is used to feed a continuous vacuum cooker. One improvement at the dissolving... 

The centres of these products are normally made as a continuous rope, either with the components previously mixed together or deposited as layers in the case where there is a layer of caramel, the caramel passes from the cooker to a cooling drum which cools the caramel to an appropriate temperature, satisfying the requirements mentioned above if the caramel is to be mixed with other ingredients, e.g. nuts, they are mixed prior to depositing. The rope of product is then cut into pieces and cooled as necessary prior to being coated with chocolate. 

Figure 9.8 describes a batch process for the production of Japanese soy sauce (koikuchi). Soybeans and defatted soybean meals are cooked in continuous pressure-cookers and mixed with roasted and coarsely broken wheat. The mass is inoculated with Aspergillus spores and incubated in shallow vats with perforated bottoms that allow air to be forced through the mass. After three days of incubation at around 30°C, mould growth covers the entire mass. This mass is called koji. Koji is the essential ingredient of most fermented products of East Asia. It is a concentrated source of enzymes necessary for breaking up the large molecules of the carbohydrates and proteins. 

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