Functional and nutritional characteristics of wheat grown in organic and conventional cropping systems

Authors: PARK, EUN - Washington State University; Baik, Byung-Kee; MILLER, PERRY - Montana State University; BURKE, IAN - Washington State University; Wegner, Eric; TAUTGES, N - Washington State University; Morris, Craig; PUERST, E. PATRICK - Washington State University

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2015
Publication Date: 9/1/2015
Publication URL: http://handle.nal.usda.gov/10113/61829
Citation: Park, E.Y., Baik, B.-K., Miller, P.R., Burke, I.C., Wegner, E.A., Tautges, N.E., Morris, C.F., Puerst, E. 2015. Functional and nutritional characteristics of wheat grown in organic and conventional cropping systems. Cereal Chemistry. 92(5):504-512.

Interpretive Summary: Consumer interest in and demand for organic wheat have grown rapidly recent years. This has been driven by the perception of organic foods as being safe and healthy, as well as an increasing concern for the sustainability of conventional crop production stemming from the heavy use of chemical fertilizers and pesticides. While grain yield and the physical and chemical characteristics of wheat grain are known to be significantly affected by environmental conditions, changes in the nutritional properties and chemical composition of wheat grain when grown under organic cultivation conditions have been either poorly understood or reported with contrasting results. We obtained both soft white winter wheat and hard red spring wheat grain from long-term field plots in Pullman, WA and Bozeman, MT to determine the effects of organic cultivation systems on the physical characteristics, nutritional quality and functional properties of grain as compared to conventional cropping systems. Organic cultivation tended to produce wheat grain of higher test weight, kernel weight and kernel diameter than the conventional system; the organic system also produced grain lower in phenolics content and antioxidant activity. Mineral content of whole wheat grain showed no apparent differences between the organic and conventional cropping systems. Soft wheat grain obtained from the low fertility organic cropping system produced flour of relatively lower protein content and water absorption capacity, which baked cookies of greater diameter and cakes of greater volume, compared to grain obtained from high fertility organic and conventional cropping systems, thus demonstrating the advantage of the low fertility organic system for production of soft wheat with improved product quality potentials.

Technical Abstract: The effects of organic vs. conventional farming practices on wheat functional and nutritional characteristics were compared. Soft white winter wheat and hard red spring wheat were obtained from long-term replicated field plots near Pullman, Washington and Bozeman, Montana. Test weight, kernel weight, and kernel diameter tended to be greater in both soft and hard organic wheat than in conventional wheat. Phenolic content and total antioxidant capacity tended to be lower in organic than in conventional wheat. The lower phenolics and antioxidants may be associated with the larger kernels in organic compared to conventional, because larger kernels have a lower proportion of the bran in which phenolic compounds are concentrated. Content of flour ash, P, and Mg content in whole wheat flour varied in parallel among cropping systems but levels were not consistently associated with either organic or conventional cropping systems. Whole wheat and refined flour protein content were similar in organic and conventional wheat when fertility levels were similar. Higher fertility led to higher protein content regardless of whether the cropping system was organic or conventional. Soft wheat flour from a very low fertility organic cropping system had lower sodium carbonate, lactic acid and sucrose solvent retention capacities, lower protein, and greater cookie diameter and cake volume than soft wheat flour from the higher fertility organic and conventional cropping systems. In the hard wheat studies, higher fertility in both organic and conventional cropping systems tended to increase protein and bread loaf volume. In conclusion, these results did not provide any compelling reason to conclude that either organic or conventional cropping systems were associated with substantially improved mineral and antioxidant nutritional properties, and end-use quality of wheat was strongly associated with fertility level more than with organic vs. conventional cropping systems.