Diejun Chen

Viscoelastic properties of oat β-glucan-rich aqueous dispersions.

C-trim is a healthy food product containing soluble dietary fibre β-glucan. The dispersion of C-trim in water is a hydrocolloid biopolymer. The linear and non-linear rheological properties of dispersions of C-trim biopolymers were investigated. The linear viscoelastic behaviours for C-trim dispersions were dependent on the β-glucan that C-trim contained. The C-trim20 and C-trim30, which have about 20% and 30% β-glucan, respectively, exhibited more fluid-like behaviours. The C-trim50 and C-trim95, which contain about 50% and 95% β-glucan, respectively, showed solid viscoelastic properties. The power law model fitting, as well as spectra, for the linear dynamic frequency sweep and stress relaxation of C-trim dispersions, suggested that the C-trim dispersions were composed of physical entanglement networks instead of chemical cross ones. The non-linear steady shearing studies for C-trim dispersions indicated that all four of the C-trim dispersions exhibited shear-thinning behaviours, which could be best described by the power law model.

Rheological and Pasting Properties of Buckwheat (Fagopyrum esculentum Möench) Flours With and Without Jet-Cooking1

ABSTRACT Pasting, rheological, and water-holding properties of buckwheat (Fagopyrum esculentum) flour obtained from whole achenes separated into three particle sizes, and three commercial flours (Fancy, Supreme, and Farinetta) were measured with or without jet-cooking. Fancy had instantaneous paste viscosity (measured using RVA) after jet-cooking that was not observed for Supreme or Farinetta, and paste viscosity was lower for the latter two flours. Supreme jet-cooked flour exhibited higher peak viscosity than flour without jet-cooking, and paste exhibited high shear-thinning. Fancy exhibited strongest viscoelastic properties (measured using a rheometer). Jet-cooking damaged buckwheat flour structure, thereby reducing viscoelasticity. Buckwheat flour pastes experienced shear-thinning over a wide range of shear rates. Jet-cooking greatly enhanced water-holding capacity. Buckwheat flour particle size did not greatly influence paste viscosity. Study showed buckwheat flours have unique pasting and rheological...

Antioxidant Activity and Phenolic Content of Air-Classified Corn Bran

ABSTRACT The effectiveness of extracting free and bound phenolic compounds and antioxidant activities from air-classified corn bran was evaluated by various extracting methods. Free phenolic contents and antioxidant activities decreased significantly with increasing particle sizes for all methods used in the study. Also, the oil, protein, and ash contents were noticeably decreased with increasing particle sizes. By contrast, bound phenolic content and antioxidant activities increased with increasing particle sizes. Free phenolic contents were much lower than those of bound phenolic contents for the same fraction. The free antioxidant activities were similar to bound antioxidant activities for the same fraction. It suggests that some phenolic compounds may not exhibit antioxidant activity, and some antioxidant activities were not extractable or released during alkaline extraction. Considerable higher free antioxidant activities were found in both direct and double extractions when compared to the single ne...

Influence of Jet-Cooking Prowashonupana Barley Flour on Phenolic Composition, Antioxidant Activities, and Viscoelastic Properties

ABSTRACT The objective was to study the influence of jet-cooked Prowashonupana barley flour on total phenolic contents, antioxidant activities, water-holding capacities, and viscoelastic properties. Barley flour was jet-cooked without or with pH adjustment at 7, 9, or 11. Generally, the free phenolic content and antioxidant activity decreased after jet-cooking, while the bound phenolic content and antioxidant significantly increased regardless of pH. Detectable levels of gallic acid, caffeic acid, ferulic acid, and p-coumaroyl-pentose in the jet-cooked barley flour hydrolysates along with vitexin were found among 21 phenolics by LC-ESI-Q-TOF-MS analysis. Jet-cooking at an elevated pH resulted in increased pasting viscosities. The oil content was decreased after jet-cooking and continued to decrease with increased pH values. Jet cooking dramatically increased water holding capacity from 179% for unprocessed flour to 643% for jet-cooked flour without pH adjustment, and water-holding capacity was greatly inc...

Physical properties of sugar cookies containing chia-oat composites.

BACKGROUND Omega-3 fatty acids of chia seeds (Salvia hispanica L.) and soluble β-glucan of oat products are known for lowering blood cholesterol and preventing coronary heart disease. Nutrim, oat bran concentrate (OBC), and whole oat flour (WOF) were composited with finely ground chia, and used in cookies at 20% replacement of wheat flour for improved nutritional and physical quality. The objective was to evaluate physical properties of chia-oat composites, dough, and cookies. RESULTS These composites had improved water-holding capacities compared to the starting materials. The geometrical properties and texture properties of the cookies were not greatly influenced by a 20% flour replacement using chia-OBC or chia-WOF composites. There was a decrease in the cookie diameter, and increases in the height of cookies and dough hardness using 20% Chia- Nutrim composite. CONCLUSION These fine-particle chia-oat composites were prepared by a feasible procedure for improved nutritional value and physical properties of foods. The cookies containing chia-oat composites can be considered a health-promoting functional food.

The Effect of Partially Substituted Lupin, Soybean, and Navy Bean Flours on Wheat Bread Quality

Many edible legumes contain high amounts of proteins, fibers, minerals and vitamins. Their essential amino acid composition and concentration complements the amino acids in wheat and other cereals. In addition, breads fortified with protein rich legumes make the breads more palatable. In this study, we evaluated breads made from wheat flour partially substituted with soybean, navy bean, and lupin flours at 10%, 20%, and 30% levels. The physicochemical properties of breads were measured and compared with the control (made from 100% wheat flour). Statistical analysis was used to assess the significance of the differences. The breads fortified with soybean, lupin and navy bean flours showed remarkable springiness, similar to the breads made from wheat flour. However, the higher amount of substitution increased the firmness of the breads, probably due to the incorporation of additional fibers and proteins into the formulations. Compared to wheat bread, the volumes of 90:10 wheat-soybean, wheat-lupin, and wheat-navy bean breads decreased about 7%, 2%, and 10%, respectively. Higher substitution levels would result in a higher reduction in volume for all legumes tested. The volume reduction as a result of legume substitution appears to be navy bean flour > soybean flour > lupin flour. The inclusion of legumes in the bread formulations imparts a slightly darker crust color and crumb color with the exception of breads with the soybean flour substitution. Lupin appears to be the best substitution candidate among the legumes tested for fortified bread making. Lupin can be presented as a high-value protein source in developing marketable foods for health conscious consumers.