The addition of corn fiber gum improves the long-term stability and retrogradation properties of corn starch

Authors: QIU, SHUANG - China Agricultural University; Yadav, Madhav; YIN, LIJUN - China Agricultural University

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2017
Publication Date: 6/12/2017
Publication URL: http://handle.nal.usda.gov/10113/5700718
Citation: Qiu, S., Yadav, M.P., Yin, L. 2017. The addition of corn fiber gum improves the long-term stability and retrogradation properties of corn starch. Journal of Cereal Science. 76:92-98.

Interpretive Summary: When starch granules are heated in excess water, they undergo a process called gelatinization. Retrogradation of gelatinized starch occurs in many starch-based food systems. Retrogradation is a process in which water separates from the gelatinized starch and the gelatinized starch molecules progressively re-associate until a fine microcrystalline precipitate forms. During the long-term storage of foods that contain gelatinized starch, retrogradation accounts for the undesirable textural changes of starch-based foods. The process of retrogradation takes place even in the solid state; for example, in the staling of cake or bread or cooked pasta. We now report that the addition of CFG to starch prevents its retrogradation. Corn Fiber Gum (CFG) is a natural dietary fiber and its addition to starch increases its nutritional value in addition to preventing its retrogradation. Many processed foods contain some kind of thickener, stabilizer and gelling agent and this CFG composite with starch has a potential to be used for these applications. Such properties may also enable it to be used as a low calorie replacement for carbohydrate additives used as thickeners, flavor carriers and suspension stabilizers in a wide variety of food products. Previously we showed that a valuable corn fiber gum (CFG) could be isolated from corn fiber. Corn fiber is a byproduct from US corn milling industries. It is an abundant low value material used for animal feed. These findings will benefit U. S. corn processors by adding value and creating additional market for their by-products. It will also benefit U. S. food industries for using starch without its retrogradation during long term storage. The generation and recovery of additional valuable products from corn milling by-products will also indirectly help to reduce overall cost of fuel ethanol produced from corn kernels.

Technical Abstract: This study was designed to test the hypothesis that the stability and physical properties of starch gels could be improved by adding small amounts of corn fiber gum (CFG). When compared with the starch gel alone, the addition of CFG (0 to 1.0 %) significantly lowered the hardness of the composite starch gel from 60.92 to 45.81 N after 14 days storage. An addition of 1.0% CFG slightly decreased the adhesiveness and springiness values of freshly cooked starch composite gels and the adhesiveness of gels after 14 days storage. The thermal characteristics of gelatinization for corn starch/CFG mixtures varied insignificantly as determined by differential scanning calorimeter (DSC) heating process, while enthalpy of retrogradation ('Hret) was 7.30 J/g for starch without CFG and 4.30 J/g for starch composite gel with 1.0% CFG. It was found that the addition of 1.0% CFG to starch significantly (p<0.5) decreased the degree of retrogradation during the long-term storage (14 days) from 61.6% to 36.5%. The addition of 1.0 % CFG retarded the syneresis of the starch system from 17.97 % and 34.93 % to 6.15 % and 26.57 % after storage at 4 degree C for 7 and 14 days respectively. The X-ray crystallization peak of starch containing 0.5-1.0 % CFG was quite diminished. The starch gel without CFG showed the lowest rapidly digestible starch (RDS) content and the highest resistant starch (RS) content in comparison to starch/CFG composite gels after 7 and 14 days storage. Over all, the addition of CFG considerably inhibits the retrogradation of corn starch gels during long-term storage.