New non-destructive method using gluten to isolate starch from plant materials other than wheat

Abstract

A new non-destructive patented method for separating starch of high purity from plant flour or "comminutates" (fine particles) is described. The method can be applied to all plant materials that have a mixture of starch and protein in their flour, including cereals such as barley, oats and rye; legumes such as peas, chickpeas and lentils; and seeds such as amaranths. The basic principle of the method is to add wheat gluten to the desired plant flour in a ratio of 10-20% (w/w) gluten/flour. Water is then added to the mixture. Upon hydration, wheat protein aggregates, and a gluten network is formed when the mixture is kneaded. This gluten network is stabilised by the disulfide bonds and other bonds that form between the protein and other flour material. The dough is left to prove for 1 h to allow protein agglomeration to proceed. The starch is then washed out of the mixed protein network with water and the suspension is separated from the protein mass with bolt cloth. The starch is recovered by centrifugation and air dried, freeze-dried or oven dried. The method is versatile and effective in producing starch of high purity. Furthermore, the technique has already been used to separate wheat starch on an industrial scale. After experimenting with adding salt, ascorbic acid, and various percentages of gluten, we conclude that when using 18% gluten and 3% salt a good yield of starch of acceptable purity can be isolated by this method, whilst ascorbic acid does not noticeably improve yield. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.