Cooling-Equilibration

The baked tortilla pieces are cooled for 3 to 20 min through a series of open tiers that discharge into the fryer. Cooling is necessary to decrease the temperature of the 

Frying of tortilla chips is characterized by starch gelatinization, formation of a yellow crust, and development of the characteristic flavor due to MaiUard reactions. Most starch gelatinization occurs during baking and throughout the first 10-15 s of 

Most commercial fryers are continuous types with direct or indirect heating elements, gas-fired tubes, or high-pressure steam tubular heaters. The most adequate fryers have continuous oil circulation between the fryer tank and the heat exchanger for precise control and distribution of the temperature, as well as metering paddles and a submerger for the control of the residence time. In addition, they are designed to continuously filter out fines and facilitate cleaning. 

For the production of lap-folded or conically shaped tortilla shells, tostadas, baskets, and related products, tortillas from coarse masa are either bent or formed into the desired configuration using special forming devices and then fried. Fryers are designed to maintain uniform temperature and make products with acceptable color and low moisture content (less than 2.0%). Frying temperature and product residence time depend on the type of product. Masa or tortilla pieces from yellow maize require lower frying temperatures than pieces from white or blends. Most corn chips are made from blends of white and yellow maizes to improve their frying characteristics. 

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Amolecular dynamics simulation can have three distinct time and temperature periods heating, simulation (run), and cooling. If you want to measure equilibrium properties of a molecular system, you can divide the simulation period into two parts equilibration and data collection. 

Cooling a molecular system after heating or equilibration can serve these functions ... 

Chromium ammonium sulfate (I2H2O) [34275-72-4 (hydr) I3548-43-I (anhydr)] M 478.4, m 94 loses 9H2O then dehydr at 300 , d 1.72. Crystd from a saturated aqueous soln at 55° by cooling slowly with rapid mechanical stirring. The resulting fine crystals were filtered on a Buchner funnel, partly dried on a porous plate, then equilibrated for several months in a vacuum desiccator over crude chromium ammonium sulfate (partially dehydrated by heating at 100° for several hours before use) [Johnson, Hu and Horton J Am Chem Soc 75 3922 1953]. 

The second stage of the process is to condition the beads, necessary because on cooling after prefoaming pneumatogen and steam within the cells condense and cause a partial vacuum within the cell. By allowing the beads to stand in air for at least 24 hours air can diffuse into the cells in order that at room temperature the pressure within the cell equilibrates with that outside. 

Trimethylsulfoxonium iodide (38 g) is dissolved in deuterium oxide (170 ml) at 80-100° and anhydrous potassium carbonate (50 mg) is added. The mixture is heated on a steam bath for 1 hr, then cooled to 0° for 2 hr before filtering. The recovered solid is re-equilibrated twice more by the same procedure using fresh deuterium oxide. Yield = 33.4 g (88 %). 

This effect was estimated from the experimental comparison of the stress-strain properties in three sample series which were brought to different phase contents by means of heat treatment. All samples were hydrogen-alloyed to a = 0.35 at T = 1053 K, then furnace cooled. Before straining, samples of the first series were maintained at the test temperature for 0.5 h. Series 2 samples were heated to the j9-phase, T = 1163 K, for 15 min, then cooled to the test temperature and treated like series 1 samples. The phase content in the third series was equilibrated by heating to 1163 K and slow cooling to 903 K before the test temperature was fixed. 

Fig. 4.5.4 Heat stability of Periphylla luciferases A, B, C and L in 20 mM Tris-HC1 buffer (pH 7.8) containing 1 M NaCl and 0.05% BSA (solid lines) or 0.01% LCC (dotted lines). The buffer (1 ml) containing a luciferase sample was placed in a glass test tube that had been pre-equilibrated at a temperature in a water-bath. After 2 min, the test tube was briefly cooled in cold water, and then luciferase activity in 10 jl1 of the solution was measured in 3 ml of the pH 7.8 buffer containing 0.3 i,M coelenterazine at 24° C. From Shimomura et al., 2001.

The ratio of the different isomeric products was found to vary with time, temperature, and initial concentration. This suggested that some kind of equilibration was occurring between isomers. I3C NMR spectroscopy of a reaction mixture showed, upon cooling, the reversible formation of a pair of signals in the anomeric region. These signals were ascribed to the anomeric carbon atoms of fructofuranosyl fluorides (10), which were presumed to be in equilibrium with the reactive fructofuranosyl cation, 11. 

Dry heat sterilization is usually carried out in a hot air oven which comprises an insulated polished stainless steel chamber, with a usual capacity of up to 250 litres, surrounded by an outer case containing electric heaters located in positions to prevent cool spots developing inside the chamber. A fan is fitted to the rear of the oven to provide circulating air, thus ensuring more rapid equilibration of temperature. Shelves within the chamber are perforated to allow good air flow. Thermocouples can be used to monitor the temperature of both the oven air and articles contained within. A fixed temperature sensor connected to a chart recorder provides a permanent record of the sterilization cycle. Appropriate door-locking controls should be incorporated to prevent interruption of a sterilization cycle once begun. 

A catalyst sample, between 1 to 10 grams, was loaded into the apparatus, evacuated, reduced in 1 atm of H2 at 250 or 450°C overnight and then evacuated at the reduction temperature before cooling and admitting H2 at the chemisorption temperature. Initial equilibration was very slow for all catalysts indicating the presence of states which are, kinetlcally, relatively inaccessible W. In some cases, 10-20 hrs were required for pressure equilibration. 

For the experiments in type C catalysts, the pellets were overfilled with cyclohexane and initially cooled to 230 K. They were then reheated in steps of 1 K and allowed to equilibrate for 10 min before each measurement. The signal was determined from 32 accumulations with an echo sequence of 20 ms echo time to ensure that the signal from the plastically crystalline phase of cyclohexane had decayed fully. The typical heating curves of cyclohexane in the fresh and coked catalyst are displayed in Figure 3.3.3(a) As the temperature is increased, larger and... 

Network Characterization. The networks were characterized by DSC (DuPont 1090 Thermal Analyzer) under nitrogen at a heating rate of 20 °C/min. Prior to the experiment the samples were preheated to 130 °C, equilibrated for 10 minutes and cooled to room temperature at 1 °C/min. Swelling experiments were conducted as described (7). 

Fig. 15 Portions of the Ca-Au-In phase diagram, showing phase distributions for a samples slowly cooled to 500°C and equilibrated, and b samples quenched from 800°C over a more limited composition region. (Reproduced with permission from [79]. Copyright 2005 American Chemical Society)...

This type of cake is often stored for a while after baking because it is to be covered with royal icing. The cake not only needs to cool but the surface needs to equilibrate with the bulk. There is a paradox that if the cake is just wrapped in greaseproof paper and kept in a tin that is not air tight there will be no problem. However, if the cake is wrapped in aluminium foil and kept in an air tight tin there is a possibility of mould formation because with the better moisture barrier any condensation or sweating can not evaporate. 

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