Figure 5.1 Pan for making high boil

Figure 5.1 Pan for making high boilings
obviously lowers the dissolved solids; however, it is wasteful in terms of the loss of energy and water treatment chemicals.
STEAM INJECTION COOKING
One highly efficient way of producing some forms of sugar confectionery is to use a steam injection cooker. These devices inject steam under pressure into a slurry of the sugar confectionery ingredients. They were originally developed for use on starch-based products where the starch needs cooking. It has since been found that machines ofthis type can also be used to make gum-containing products where the machine is used to dissolve and de-aerate a slurry of sugar glucose syrup and instant gum acacia. Here, the steam and slurry can be held under pressure to cook or dissolve the ingredients in the slurry and by altering the pump rates and the back pressure the degree of cooking can be altered. When the liquids emerge from the cooker the reduction in pressure causes excess steam to flash off. The efficiency of this type of cooker comes because not only is the sensible heat used but also the latent heat of the steam. However, the disadvantage of this type of machine is that the steam has become an ingredient and must therefore be food grade, and this does restrict the boiler treatment chemicals that can be used.
VACUUM COOKING
Applying a vacuum has the effect of reducing the boiling point. The boiling point of any liquid is the point at which the vapour pressure matches that of the atmospheric pressure. Thus, lowering the atmo- spheric pressure allows a mixture to be concentrated at a lower temperature. The consequences of this are considerable: working lower temperatures saves energy; it reduces heat damage; it also speeds
the process up. Applying a vacuum to a mass that is currently boiling also causes a rapid reduction in water content as the water flashes into the vapour phase. The system then cools rapidly to the boiling point at the new pressure. This effect is beneficial because it saves energy (as opposed to boiling in an open pan), the cost of higher steam pressures is avoided and the product is de-aerated. Many of the mixtures that are boiled to make confectionery contain ingredients that stabilise bubbles. In a product where bubbles are not wanted, removing them can be difficult without the use of vacuum. A typical vacuum cooker is shown in
CONTINUOUS PLANT
Many process industries have converted from batch to continuous plant. Using a continuous plant is not as easy in the food industry as it is in the chemical industry since considerations of hygiene must now be added The plant, therefore, will have to stop periodically for cleaning although continuous plants do tend to produce a more consistent product than batch processes. The most general problems with a continuous plant normally occur in setting up
A particular confectionery industry problem is the long product life. A long-established product, initially made by a batch process, must retain the same qualities when prepared by a more modern continuous plant process, and a great deal of work can go into making the two products exactly the same. In general, however, the continuous plants are more effective at heating the product and produce less sucrose inversion, although, even after the recipe has been adjusted to account for this, textural differences sometimes persist.