Shear Thinning Properties of Sorghum and Corn Starches

The paste viscosities of sorghum and corn starches were studied with a Brabender viscograph. Sorghum starches and the laboratory-prepared corn starch gave higher paste consistencies than did the two commercial corn starches. Considerable variation existed in shear thinning of starches. In general, sorghum starches shear-thinned more than corn starches, although certain sorghum starches gave low shear thinning. When the hot pastes were sheared at high speed, sorghum starches thinned more than corn starches. The gelatinization characteristics did not appear to be related to shear thinning of sorghum starches. Swelling power at 95 C was lower for corn starch than it was for sorghum starch. Solubility of both corn and sorghum starches at 95 C varied among the cultivars. The reasons for high shear thinning of certain sorghums requires further investigation

Factors Affecting the Color and Appearance of Sorghum Starch

Seven cultivars of grain sorghum with various seed colors were studied for the presence of light-absorbing substances in the grain and starch. A corn sample was used for comparison. Starch was isolated from both sorghum and corn. Corn starch was bright in appearance and had a yellowish tinge. Sorghum starch from the cultivars Dorado, UANL-1-V-187, and Blanco 88 was also bright in appearance and white; the seed color was pale yellow. Although Sorghum cultivar Dekalb 42Y had a pale yellow seed color, it yielded a dull-appearing starch. Kansas local, Bajio, and Tamaulipas cultivars had reddish-brown seed color and also yielded dull-appearing starch that had a reddish tint. It appears that the presence of certain alcohol-soluble components contributes to the dullness of some sorghum starches, because extraction of dull starch with methanol resulted in a brighter starch. Dehulling of the grain before starch isolation improved the appearance of starch. A simple alkali test on the grain was effective in predicting the dullness of starch

Delayed gastric emptying and reduced postprandial small bowel water content of equicaloric whole meal bread versus rice meals in healthy subjects: novel MRI insights

BACKGROUND/OBJECTIVES: Postprandial bloating is a common symptom in patients with functional gastrointestinal (GI) diseases. Whole meal bread (WMB) often aggravates such symptoms though the mechanisms are unclear. We used magnetic resonance imaging (MRI) to monitor the intragastric fate of a WMB meal (11% bran) compared to a rice pudding (RP) meal. SUBJECTS/METHODS: 12 healthy volunteers completed this randomised crossover study. They fasted overnight and after an initial MRI scan consumed a glass of orange juice with a 2267 kJ WMB or an equicaloric RP meal. Subjects underwent serial MRI scans every 45 min up to 270 min to assess gastric volumes and small bowel water content and completed a GI symptom questionnaire. RESULTS: The MRI intragastric appearance of the two meals was markedly different. The WMB meal formed a homogeneous dark bolus with brighter liquid signal surrounding it. The RP meal separated into an upper, liquid layer and a lower particulate layer allowing more rapid emptying of the liquid compared to solid phase (sieving). The WMB meal had longer gastric half emptying times (132±8 min) compared to the RP meal (104±7 min), P<0.008. The WMB meal was associated with markedly reduced MRI-visible small bowel free mobile water content compared to the RP meal, P<0.0001. CONCLUSIONS: WMB bread forms a homogeneous bolus in the stomach which inhibits gastric sieving and hence empties slower than the equicaloric rice meal. These properties may explain why wheat causes postprandial bloating and could be exploited to design foods which prolong satiation

Physicochemical properties and structural characteristics of whole grain Oryza sativa L. with different treatments

[EN] Physicochemical properties and structural characteristics of whole rice flours with different treatments (soaking, germination and extrusion cooking) were studied. Water solubility, water absorption, crystallinity, adsorption isotherms (BET and GAB models), and glass transition temperature of the samples were determined. Water solubility and water absorption were enhanced by extrusion cooking process (3.17 4.98 vs. 24.1 53.76 g/100 g and 2.77 3.05 vs. 4.46 7.04 ml/g, respectively), but crystallinity was decreased (30 33 vs. 4 16%). Adsorption isotherms showed that extruded samples exhibited higher equilibrium moisture content as compared with their corresponding non-extruded samples (5.0 19.2 vs. 4.0 16.1 g water/g solids). There were no changes in glass transition temperature values in the studied moisture range (3.8 16 g/100 g). These results allow the correct use of whole rice flours with different treatments in foods and also contributed to the knowledge of stabilization of the productsThe author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was partially financed by ANPCYT (PICT 1105) and ERASMUS MUNDUS ACTION 2 ARCOIRIS Fellowship.Albarracin, M.; Talens Oliag, P.; Martínez Navarrete, N.; González, RJ.; Drago, SR. (2016). Physicochemical properties and structural characteristics of whole grain Oryza sativa L. with different treatments. Food Science and Technology International. 22(4):1-10. doi:10.1177/1082013215600078S110224Albarracín, M., José González, R., & Drago, S. R. (2015). Soaking and extrusion effects on physicochemical parameters, phytic acid, nutrient content and mineral bio-accessibility of whole rice grain. 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LWT - Food Science and Technology, 37(2), 193-198. doi:10.1016/j.lwt.2003.07.004Gonzalez, R., Drago, S., Torres, R., & De Greef, D. (2013). Extrusion Cooking of Cereal-Based Products. Contemporary Food Engineering. doi:10.1201/b15246-13González, R. J., Pastor Cavada, E., Vioque Peña, J., Torres, R. L., De Greef, D. M., & Drago, S. R. (2013). Extrusion Conditions and Amylose Content Affect Physicochemical Properties of Extrudates Obtained from Brown Rice Grains. International Journal of Food Science, 2013, 1-8. doi:10.1155/2013/584148Herawat, H., Kusnandar, F., Adawiyah, D. R., Budijanto, S., & Rahman, M. S. (2014). Thermal characteristics and state diagram of extruded instant artificial rice. Thermochimica Acta, 593, 50-57. doi:10.1016/j.tca.2014.08.017Jones, J. M., & Engleson, J. (2010). Whole Grains: Benefits and Challenges. Annual Review of Food Science and Technology, 1(1), 19-40. doi:10.1146/annurev.food.112408.132746Kim, H. Y., Hwang, I. G., Kim, T. M., Woo, K. S., Park, D. S., Kim, J. H., … Jeong, H. S. (2012). Chemical and functional components in different parts of rough rice (Oryza sativa L.) before and after germination. Food Chemistry, 134(1), 288-293. doi:10.1016/j.foodchem.2012.02.138Lowry, R. R., & Tinsley, I. J. (1976). Rapid colorimetric determination of free fatty acids. Journal of the American Oil Chemists’ Society, 53(7), 470-472. doi:10.1007/bf02636814Matveev, Y. (2000). The plasticizing effect of water on proteins, polysaccharides and their mixtures. Glassy state of biopolymers, food and seeds. Food Hydrocolloids, 14(5), 425-437. doi:10.1016/s0268-005x(00)00020-5Perdon, A., Siebenmorgen, T. J., & Mauromoustakos, A. (2000). Glassy State Transition and Rice Drying: Development of a Brown Rice State Diagram. Cereal Chemistry Journal, 77(6), 708-713. doi:10.1094/cchem.2000.77.6.708ROOS, Y., & KAREL, M. (1991). Plasticizing Effect of Water on Thermal Behavior and Crystallization of Amorphous Food Models. Journal of Food Science, 56(1), 38-43. doi:10.1111/j.1365-2621.1991.tb07970.xRuiz-Ruiz, J., Martínez-Ayala, A., Drago, S., González, R., Betancur-Ancona, D., & Chel-Guerrero, L. (2008). Extrusion of a hard-to-cook bean (Phaseolus vulgaris L.) and quality protein maize (Zea mays L.) flour blend. LWT - Food Science and Technology, 41(10), 1799-1807. doi:10.1016/j.lwt.2008.01.005SIU, G. M., & DRAPER, H. H. (1978). A SURVEY OF THE MALONALDEHYDE CONTENT OF RETAIL MEATS AND FISH. Journal of Food Science, 43(4), 1147-1149. doi:10.1111/j.1365-2621.1978.tb15256.xSun, Z., Yang, W., Siebenmorgen, T., Stelwagen, A., & Cnossen, A. (2002). Thermomechanical Transitions of Rice Kernels. Cereal Chemistry Journal, 79(3), 349-353. doi:10.1094/cchem.2002.79.3.349Timmermann, E. O. (2003). Multilayer sorption parameters: BET or GAB values? Colloids and Surfaces A: Physicochemical and Engineering Aspects, 220(1-3), 235-260. doi:10.1016/s0927-7757(03)00059-1Tovar, J., Bjoerck, I. M., & Asp, N. G. (1990). 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Distribution of lipids in the grain of wheat (cv Hereward) determined by lipidomic analysis of milling and pearling fractions

Lipidomic analyses of milling and pearling fractions from wheat grain were carried out to determine differences in composition which could relate to the spatial distribution of lipids in the grain. Free fatty acids and triacylglycerols were major components in all fractions, but the relative contents of polar lipids varied, particularly lysophosphatidyl choline and digalactosyldiglyceride, which were enriched in flour fractions. By contrast, minor phospholipids were enriched in bran and offal fractions. The most abundant fatty acids in the analysed acyl lipids were C16:0 and C18:2 and their combinations, including C36:4 and C34:2. Phospholipids and galactolipids have been reported to have beneficial properties for bread making, while free fatty acids and triacylglycerols are considered detrimental. The subtle differences in the compositions of fractions determined in the present study could therefore underpin the production of flour fractions with optimised compositions for different end uses

Developments in the science of zein, kafirin, and gluten protein bioplastic materials

Despite much research, there are very few commercial prolamin bio-plastics. The major reason, apart from their high cost, is that they have inferior functional properties compared to synthetic polymer plastics. This is because the prolamins are complex, each consisting of several classes and sub-classes and the functional properties of their bio-plastics are greatly affected by water. Prolamin bio-plastics are produced by protein aggregation from a solvent or by thermoplastic processing. Recent research indicates that protein aggregation occurs by polypeptide self-assembly into nanostructures. Protein secondary structure in terms of α- helical and β-sheet structure seems to play a key, but incompletely understood role in assembly. Also, there is inadequate knowledge as to how these nanostructures further assemble and organize into the various forms of prolamin bio-plastics such as films, fibres, microparticles and scaffolds. Some improvements in bio-plastic functionality have been made by better prolamin solvation, plasticization, physical and chemical cross-linking, derivatization and blending with other polymers. The most promising area of commercialization is the biomedical field where the relative hydrophilicity, compatibility and biodegradability of particularly zein and kafirin are advantageous. With regard to biomedical applications, “supramolecular design” of prolamin bio-plastics through control over interand intramolecular weak interactions and SS/SH interchange between and within polypeptides appears to have considerable potential.University of Pretoria doctoral bursaryhttp://cerealchemistry.aaccnet.org/hb201