Extruding biscuits

Meat products, e.g. beef, chicken, pork, lamb Vegetables, e.g. onions, potatoes, garlic Roasted products, e.g. coffee, cocoa, roasted nuts, popcorn Cereal products, e.g. biscuits, bread, extrudates Beverages, e.g. beer, wine, whiskey... 

Crispness is a desirable sensory property in many cereal foods such as toast, the crust of bread, crispbreads, crisps, biscuits, extruded snacks and breakfast cereals. Since it is a subjective sensory assessment crispness is difficult to define unambiguously and its perception varies greatly between individuals and also between countries (Bourne 2002). In general it is known that crisp foods are at low moisture, in the brittle or glassy state well above Tg and fracture rapidly (see also Chapters 5 and 7). We can... 

Most low-moisture cereal-based foods (e.g., biscuits, extruded products, potato chips, etc.) have a crunchy or crisp texture that is lost as the moisture content increases either by redistribution within the product or moisture pick-up from the environment. The loss of crispness of cereal products and... 

Sandwiches consist of one or more flavours of ice cream between two biscuits or wafers, which may have been covered in chocolate (Figure 5.4a). Biscuits are made by mixing flour, sugar and fat, shaping and then baking. The sandwich can be assembled layer by layer, i.e. the first biscuit or wafer is covered with ice cream, which in turn is covered with a second biscuit or wafer. Alternatively, the ice cream can be extruded between two biscuits. The product is then hardened, dipped in chocolate or couverture if required, and packaged. 

Ordinary butter (the toast type) is another example of a liquid/semisolid, depending on temperature. Butter is really a slurry of water in fat, differing from many materials of similar stiff room temperature textures in that its production is essentially a room temperature operation. Materials of this type can be sampled with a core-type sampler in the semisolid state or by methods previously described, in the liquid state. They can also be sampled by an extmsion system, whereby the sample is chopped off from an extruded stream. It is important that temperature be controlled so that the cut surface remains level and does not start to flow. Cheese is even more solid and can be sampled by simply taking a slice. Processed cheese is usually manufactured in the liquid state, and can be sampled and analyzed as-is, or fed into a sampling cell and allowed to solidify before analysis. Crumbly materials, such as biscuit (cookie) or cake doughs, dough mixes for pasta or noodle production or compressed (fresh) yeast, can be sampled manually or by an extrusion system. This includes thick slurries, which will eventually either solidify or be compressed into solid sheets or blocks. 

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