Gluten yield

The Zeleny (Zeleny 1947), sedimentation, and microsedimentation tests (AACC Methods 56-60,56-61A and 56-63) are based on a 5 min sedimentation volume of a fixed flour-water slurry stained with bromophenol and a weak acidic acetic-isopropanol solution (Figure 15.4). Samples containing high gluten yield higher sedimentation values. The values are also adjusted according to protein content. 

Protein-Based Substitutes. Several plant and animal-based proteins have been used in processed meat products to increase yields, reduce reformulation costs, enhance specific functional properties, and decrease fat content. Examples of these protein additives are wheat flour, wheat gluten, soy flour, soy protein concentrate, soy protein isolate, textured soy protein, cottonseed flour, oat flour, com germ meal, nonfat dry milk, caseinates, whey proteins, surimi, blood plasma, and egg proteins. Most of these protein ingredients can be included in cooked sausages with a maximum level allowed up to 3.5% of the formulation, except soy protein isolate and caseinates are restricted to 2% (44). 

Commercial starch is mainly com starch, but smaller amounts of sorghum, wheat, and potato starch are also produced. In 1992, 1303 million bushels (45.8 X 10 m ) of com were ground for starch and other products (120) 1 m com weighs - 721 kg and yields 438 kg starch, 26 kg oil, and 142 kg combined gluten and hulls. In the United States in 1994—1995, 462 million bushels were used to produce high fmctose com symp, 231 million bushels went to produce D-glucose, 533 million bushels were used for alcohol production, and 247 million bushels were converted to starch (121). 

With practice this method gives concordant results. As regards the extraction of the gluten, this is easy with fine wheat flour and ordinary bread flour, but difficult with inferior flours, and the latter may conveniently be manipulated under the water in a thin linen bag. Flours of other cereals do not yield gluten when treated in this way. 

If gluten flour (40 per cent gluten) is used instead of ordinary flour, the procedure is approximately the same. A 5-lb. sack of gluten flour is washed to remove the starch. The wet gluten is placed in a 6-1. Pyrex flask with 3500 cc. of concentrated hydrochloric acid (sp. gr. 1.19) and the hydrolysis is carried out as described above. After the hydrolysis and removal of the melanin by filtration, the solution is concentrated to about 1300 cc. The glutamic acid hydrochloride is then precipitated as already described. After two recrystallizations, the yield is 180-190 g. From the mother liquors a further yield of 45-50 g, is obtained, making a total of 225-230 g. 

Gluten obtained by tabling seldom contains more than 50% protein. To approximate the results obtained by continuous commercial centrifugation, gluten and squeegee data were recalculated to 70% protein, which increases starch yield. Similar... 

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