Differences in Carbohydrate Composition and Digestion In Vitro of Selected Barley Cultivars as Influenced by Pearling and Cooking

Among common cereals, barley is a low glycemic index food. In an attempt to better understand this character, the nutritional properties of glycemic carbohydrates and dietary fiber concentrations of nine cultivars were evaluated. The cultivars were selected based on botanical variations and commercial value to investigate the impact of pearling and cooking on nutritional properties. Each cultivar was pearled into four fractions ranging from hull removal only to hull, bran, germ, and crease removal. The study showed that botanical class and degree of pearling significantly affect the carbohydrate composition and digestion indices of barley. Waxy starch cultivars had less total starch and more rapidly digestible starch (RDS), rapidly available glucose (RAG), and β‐glucan than the other nonwaxy cultivars. Regardless of the barley type, the less pearled kernels had significantly lower total starch and higher total low molecular weight sugars, insoluble, and total fiber. However, β‐glucan content was fairly comparable in the whole grain and pearled fractions. Cooking had a significant effect on nutritional properties of Celebrity and AC Klinck cultivars. The only consistent significant difference between raw and cooked barley was resistant starch (RS), which increased after cooking regardless of cultivar or fraction. The study showed that barley cultivar and carbohydrate composition significantly affected starch digestion with some cultivar fractions holding a promise for the development of low glycemic index foods.     

REVIEW: Molecular Interactions in Starch‐Water Systems: Effect of Increasing Starch Concentration

Starch is a major part of our diet. Food processing determines the physicochemical properties of starch in processed foods. An understanding of such properties is important in the development of strategies to modulate desirable textural attributes as well as the digestibility of starch in foods such as baked and extruded products. This review summarises the molecular interactions that occur during gelatinization and retrogradation of starch molecules studied using starch‐water systems focusing on those with starch concentrations of 60–150% db relevant to baked and extruded foods. Little information exists on effects of starch concentration on digestibility and polymer conformations and structures of processed starch in concentrated systems.     

Pseudomonas-induced defence molecules in rice plants against leaffolder (Cnaphalocrocis medinalis) pest

Fluorescent pseudomonad strains Pf1, TDK1 and PY15 individually and in combination were evaluated against leaffolder, Cnaphalocrocis medinalis Guen., in rice under in vitro, glasshouse and field conditions. Among the various treatments used, a combination of Pf1, TDK1 and PY15 strains effectively reduced the incidence of leaffolder pest in rice plants to an extent comparable with chlorpyrifos-methyl. In addition, morphogenesis of the insect pest in all stages, larval, pupal and adult, was greatly affected by a combination of Pseudomonas Pf1, TDK1 and PY15 strains. Further, the induction of defence-related molecules was demonstrated. An increased accumulation of defence molecules such as chitinase and proteinase inhibitors was observed with a combined Pf1, TDK1 and PY15 treatment compared with all other treatments. Western blot analysis of chitinase revealed the extra induction of 18, 28 and 35 kDa isoforms in rice plants treated with a mixture of Pf1, TDK1 and PY15 strains against leaffolder pest. The study revealed that a combination of fluorescent pseudomonad strains affects the development of leaffolder pest by inducing defence molecules in rice plants which in turn enhance resistance to leaffolder attack.     

Effect of Transglutaminase,Citrate Buffer,and Temperature on a Soft Wheat Flour Dough System

Transglutaminase (TGase) can improve the functional characteristics of proteins by introducing covalent bonds inter‐ or intrachains. Temperature and pH interfere with the protein structure and the catalytic activity of enzymes. Because these three factors can act synergistically, TGase, citrate buffer, and temperature were evaluated for their effects on the rheological and chemical changes in low‐protein wheat flour dough. Dough strength, measured by microextension test, significantly increased with increasing levels of TGase (8 U/g of protein), with changes in pH of the citrate buffer (pH 6.5), and by the effect of interaction between these factors. The same trend was observed in the size‐exclusion HPLC measurements, indicating that these two parameters have the effect of increasing gluten protein aggregation. Temperature had a significant effect on dough extension, measured by microextension test. The changes in secondary structure of gluten protein were investigated by FTIR second‐derivative spectra (amide I region, 1,600–1,700 cm⁻¹) and showed an increase in β‐sheet structures initiated by TGase, citrate buffer pH, and their interaction.     

Musings on the Architecture and Molecular Arrangement of Polymers in Starch Granules Based on Iodine

The molecular architecture of starch has been the focus of research for over two centuries. However, studies toward understanding the granular architecture of starch have been limited to the crystalline lamellae, and the composition, structure, and organization of polymers in the amorphous background still remain unclear. This essay summarizes some recent results based on novel experiments with iodine vapor–granular starch interactions that occur in the amorphous regions of the granule. In combination with atomic force microscopy, light microscopy, powder spectrophotometry, and X‐ray diffractometry, iodine binding was used to explore the amorphous structures and the architecture of the granule. Results based on heating starch granules in the presence of iodine and their implications are also presented.     

Effect of iodine on polymer leaching and granule swelling of starches from different botanical sources

Iodine complexation with linear glucan polymers in starch granules is a function of the length of the available polymers and their arrangement within starch granules. In previous studies, this complex formation between iodine and glucan polymers has been shown to alter the pasting properties of starches from different botanical origins. In this study, the effect of iodine on the swelling capacities of corn (CS), wheat (WS), potato (PS) and tapioca (TS) starches was investigated by heating 8% starch slurry with different levels of iodine in a Rapid Visco Analyser (RVA). Increasing concentrations of iodine had an inverse effect on the swelling capacities of starches even though the granules were highly swollen, as observed in the micrographs. Furthermore, the composition of the leachate was different for the starches, suggesting that the swelling capacity was influenced largely by an increase or decrease in the amount of leachate and the absorption spectra of the leachate. The same amounts of iodine resulted in widely different swelling capacity values for the different starches, likely, suggesting differences in their granular architecture.     

Influence of phenolic acid content on sensory perception of bread and crackers made from red or white wheat

Despite the health benefits of wholegrain, consumer acceptance of wholegrain products remains an issue due to the presence of characteristic flavours that some consumers consider to be unacceptable. It was hypothesized that phenolic acids could be contributing to the perceived unacceptable flavours described in wholegrain products. The purpose of this study was to examine the relationship between total phenolic acid content (TPAC) and phenolic acids as quantified by HPLC, to the sensory properties of wholegrain products using partial least squares (PLS) mapping. Red and white wheat flours were investigated in an intermediate (bread) and low (cracker) moisture product system. Red and white wheat demonstrated different phenolic acid profiles despite having similar TPAC. Within the bread crumb, the free and bound phenolic acids provided the best predictive scores; whereas only bound phenolic acids provided high predictive scores in crackers. This suggests that the contribution of phenolic acids to flavour characteristics of wholegrain products varies depending upon the product moisture.     

Induction of systemic resistance to Xanthomonas oryzae pv. oryzae by salicylic acid in Oryza sativa (L.)

Journal of Plant Diseases and Protection - The effect of salicylic acid (SA) is hypothesized to be a natural signal that triggers the systemic induction of phenolics, pathogenesis-related proteins...     

Structural Properties of Starch Fractions Isolated from Normal and Mutant Corn Genotypes Using Different Methods

The objectives of this research study were to isolate, evaluate, and compare the fine structures of starch fractions obtained from a wild‐type (normal) corn starch and amylose‐extender25, dull39, sugary2, and sugary1 corn mutants in the same genetic background using three different fractionation procedures based on gel‐permeation chromatography or alcohol‐precipitation methods. Starch fractions obtained from each of the three methods were enzymatically debranched and analyzed using high‐performance anion‐exchange chromatography with a postcolumn amyloglucosidase reactor and a pulsed amperometric detector. The separations were performed by fractionation on a GPC column, by precipitation with 1‐butanol, and by preferential precipitation with 1‐butanol and isoamyl alcohol. Using any of these methods, no apparent differences in the molecular weight distributions of amylopectin or of amylose among the different starches were observed. The proportions of branch chain lengths of the starch components obtained by the various fractionation methods were very similar among methods for each of the starch types analyzed, such as the predominance of long branch chains in ae25 corn and that of the short branch chains in su2 corn. Overall, the effect of the corn mutations was more important to the differences observed among the starch types than was the method of fractionation used.