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.

Methods for Extracting Cereal Starches from Different Sources: A Review

“…Al‐Hakkak and Al‐Hakkak isolated oat starch using wheat gluten. In this method, wheat gluten was added to oatmeal (18 g of gluten per 100 g of oatmeal).…”

“…Al‐Hakkkak and Al‐Hakkak developed and patented a wheat gluten‐based nondestructive method to isolate starch from cereal flours, including barley flour. In this method, the wheat gluten is added to the barley flour before the water addition.…”

Barley Starch: Composition, Structure, Properties, and Modifications

“…The major difficulty associated with barley starch isolation is the presence of β‐glucans that give a high viscosity of the slurry during extraction. There have been a few improvements in starch isolation methods with improved yield and/or starch purity (Al‐Hakkak and Al‐Hakkak ; Gao and others ; Rittenauer and others ). An aqueous alcohol‐based enzymatic method was developed to mask the impact of high viscosity due to the endogenous β‐glucans (Gao and others ).…”

“…Compared with the traditional alkaline extraction method, the papain‐based method gives a higher starch yield (Sharma and Tejinder ). A wheat gluten‐based nondestructive method to isolate starch from various flours, including barley flour, has been developed and patented (Al‐Hakkak and Al‐Hakkak ). Wheat gluten is added to the barley flour (10% to 20% gluten/flour (w/w)) before adding water for hydration.…”

“…Starch is washed out from the dough and the slurry is washed and sifted to further purify the starch. The starch yield from barley flour was 77.6%, though the purity was not given (Al‐Hakkak and Al‐Hakkak ). A method to isolate starch from malted barley has been developed on the basis of dry milling, microsieving, and density gradient centrifugation (Rittenauer and others ).…”