TECHNOLOGY OF CEREALS djuncts-sugar, malt syrup, salt -is added tion. During this time, the kernels firm up with more water. The dough is cooked in the because of retrogradation of the starch: this cooking extruder and is transferred to a forming firming is essential for obtaining shreds of adequate extruder in which a non-cooking temperature strength. The conditioned grain is fed into shred- below 71oC-is maintained. The extruded collets ders consisting of a pair of metal rolls- one is are dried from 20-24%m c. to 9-12% m c and smooth, the other has grooves between which the then gun-puffed at 260-427oC and 100-200 lb/ material emerges as long parallel shreds. the in pressure as previously described(Fast and shreds are detached from the grooves by the teeth Caldwell, 1990; Rooney and Se Saldivar, 1987).a of a comb and fall onto a slowly travelling band 10-16-fold expansion results a thick mat being built up by the superimposition of several layers. The mat is cut into tablets Puffed wheat by a cutter which has dull cutting edges: the squeezing action of the cutter compresses the a plate wheat called Tagenrog is the type of shreds and makes them adhere to one another wheat preferred for puffing on account of its The tablets are baked at 260oC in a gas-heated puffs, but durum or CWRS wheat may alo ge revolving oven or a conveyor-belt oven, taking large grain size which gives high yields of lar e about 20 min The major heat input is at the feed y The wheat is pretreated with about 4% of a is lost in the middle section, while colour is end; the biscuits increase in height as moisture saturated brine solution (26% salt content) to developed in the final section. The moisture toughen the bran during preheating and make it content of the biscuits is about 45% entering the cohesive, so that the subsequent puffing action oven, about 4% leaving the oven. The biscuits blows the bran away from the grain, thereby may be further dried to 1%m c, passed through improving its appearance Alternatively, the bran a metal detector, and then packaged(Fast, 1987; can be partly removed by pearling on carborun- Fast and Caldwell, 1990) dum stones. The puffing process is similar to that Shredded products may also be made from the described for rice(Fast and Caldwell, 1990) four of wheat, maize, rice or oats which would be cooked in batches or by continuous extrusion Continuous cooking Flavouring and nutritional adjuncts may be added After cooking, cooling and equilibra Using a steam- pressurized puffing chamber, tion for 4-24 h, the material is shredded and the prepared grain is admitted through valves and baked as described above. When using maize or subsequently released through an exit pore with- rice to make a shredded product, however, it is out loss of pressure in the chamber(U.S. Pat. desirable to produce a degree of puffing to avoid No.3,971,303) hardness. This is achieved by using a lower emperature in the first part of the baking Shredded products followed by an extremely high temperature in the Wheat is the cereal generally used, a white, starchy type, such as Australian, being preferred The whole grain is cleaned and then cooked in Granular products min until the centre of the kernel changes from A yeasted dough is made from a fine wholemeal starchy white to translucent grey, and the grain or long extraction wheaten four and malted is soft and rubbery. The moisture content is 45- barley flour, with added salt. The dough is 50%, and the starch is fully gelatinized. The fermented for about 6 h and from it large loaves cooked grain is cooled to room temperature and are baked. These are broken up, dried and rested for up to 24 h to allow moisture equilibra- ground to a standard degree of fineness2 50 TECHNOLOGY OF CEREALS adjuncts - sugar, malt syrup, salt - is added with more water. The dough is cooked in the cooking extruder and is transferred to a forming extruder in which a non-cooking temperature - below 71°C - is maintained. The extruded collets are dried from 20-24% m.c. to 9-12% m.c. and then gun-puffed at 26Oo-427"C and 100-200 Ib/ in2 pressure as previously described (Fast and Caldwell, 1990; Rooney and Se Saldivar, 1987). A 10-16-fold expansion results. Puffed wheat A plate wheat called Tagenrog is the type of wheat preferred for puffing on account of its large grain size which gives high yields of large puffs, but durum or CWRS wheat may also be used. The wheat is pretreated with about 4% of a saturated brine solution (26% salt content) to toughen the bran during preheating and make it cohesive, so that the subsequent puffing action blows the bran away from the grain, thereby improving its appearance. Alternatively, the bran can be partly removed by pearling on carborun￾dum stones. The puffing process is similar to that described for rice (Fast and Caldwell, 1990). Continuous puffing Using a steam-pressurized puffing chamber, the prepared grain is admitted through valves and subsequently released through an exit pore with￾out loss of pressure in the chamber (U.S. Pat. No. 3,971,303). Shredded products Wheat is the cereal generally used, a white, starchy type, such as Australian, being preferred. The whole grain is cleaned and then cooked in boiling water with injection of steam for 30-35 min until the centre of the kernel changes from starchy white to translucent grey, and the grain is soft and rubbery. The moisture content is 45- 50%, and the starch is fully gelatinized. The cooked grain is cooled to room temperature and rested for up to 24 h to allow moisture equilibra￾tion. During this time, the kernels firm up because of retrogradation of the starch: this firming is essential for obtaining shreds of adequate strength. The conditioned grain is fed into shred￾ders consisting of a pair of metal rolls - one is smooth, the other has grooves between which the material emerges as long parallel shreds. The shreds are detached from the grooves by the teeth of a comb and fall onto a slowly travelling band, a thick mat being built up by the superimposition of several layers. The mat is cut into tablets by a cutter which has dull cutting edges: the squeezing action of the cutter compresses the shreds and makes them adhere to one another. The tablets are baked at 260°C in a gas-heated revolving oven or a conveyor-belt oven, taking about 20 min. The major heat input is at the feed end; the biscuits increase in height as moisture is lost in the middle section, while colour is developed in the final section. The moisture content of the biscuits is about 45% entering the oven, about 4% leaving the oven. The biscuits may be further dried to 1% m.c., passed through a metal detector, and then packaged (Fast, 1987; Fast and Caldwell, 1990). Shredded products may also be made from the flour of wheat, maize, rice or oats which would be cooked in batches or by continuous extrusion cooking. Flavouring and nutritional adjuncts may be added. After cooking, cooling and equilibra￾tion for 4-24 h, the material is shredded and baked as described above. When using maize or rice to make a shredded product, however, it is desirable to produce a degree of puffing to avoid hardness. This is achieved by using a lower temperature in the first part of the baking, followed by an extremely high temperature in the last part. Granularproducts A yeasted dough is made from a fine wholemeal or long extraction wheaten flour and malted barley flour, with added salt. The dough is fermented for about 6 h and from it large loaves are baked. These are broken up, dried and ground to a standard degree of fineness