Thava Vasanthan

Starch from hull-less barley: I. Granule morphology, composition and amylopectin structure

Starch was extracted from 10 hull-less barley (HB) genotypes [waxy (CDC Candle, CDC Alamo, SB 94912, and SB 94917), normal amylose (Phoenix, CDC Dawn, SR 93102, and SB 94860), and high amylose (SB 94893 and SB 94897)]. Starch content ranged from 56 to 65%. The purity of the isolated starches was greater than 96%. Average starch yield and extraction efficiency were 44 and 71%, respectively. The starches from all genotypes consisted of a mixture of large lenticular and small irregularly shaped granules. The granules of most starches were intact, whereas in others (SB 94917, SR 93102, and SB 94860) they were compound (clustered). The proportions of small (diameter⩽10 μm) and large granules (diameter>10 μm), by total number and by total weight differed among genotypes. Bound lipid content was positively correlated (r=0.92, P<0.01) with total amylose content. Free and bound lipid contents ranged from 0.1–0.3% and 0.3–1.7%, respectively. The apparent and total amylose contents ranged from 0–39% and 0–45%, respectively. The amounts of amylose complexed with native lipids (total amylose–apparent amylose) ranged from 0.5 to 7.8%. The proportion of small granules was correlated with total amylose content (r=0.59, P<0.1). However, the average granule diameter was negatively correlated (r=−0.65, P<0.05) with total amylose content. The debranched amylopectins of all starches exhibited the highest peak in the MALDI-MS spectrum at DP 12. The average chain length (CL) and degree of branching ranged from 17.6–22.7% and 4.4–5.5%, respectively. The short (DP 5-17) and long (DP⩾35) chains ranged from 58.2–59.1% and 3.0–12.8%, respectively. The study showed that amylose/amylopectin ratio and amylopectin branch chain length have high correlation with granule size and size distribution in this set of barley genotypes.

Hypochlorite oxidation of field pea starch and its suitability for noodle making using an extrusion cooker

Abstract The effect of hypochlorite oxidation on the Brabendar pasting properties of field pea starch and the suitability of native and oxidized starch for noodle making by extrusion cooking were investigated. Field pea starch was oxidized with sodium hypochlorite at a level of active chlorine ranging from 0.89 to 3.28% (starch db). The degree of oxidation was determined and expressed in terms of percentage of carboxyl and carbonyl groups, which ranged from 0.02 to 0.38% and 0.06 to 0.19%, respectively. Starch recovery and peak viscosity, hot paste viscosity, cool paste viscosity, and setback of oxidized starches decreased with increasing degree of oxidation. The cooking quality attributes of noodles prepared from native field pea starches were acceptable but were negatively influenced by hypochlorite oxidation. Substitution of potato starch (40%, db) for field pea starch yielded more glossy noodles with better cooking quality. It was also observed that Brabendar pasting properties had high correlations with noodle quality characteristics.

Volatile flavour composition of cooked by-product blends of chicken, beef and pork : a quantitative GC-MS investigation

Abstract Volatile flavour composition of cooked chicken (CB), beef (BB) and pork (PB) by-product blends was investigated using gas chromatography–mass spectrometry (GC–MS) and the results were compared with those for cooked chicken white muscles (CM), beef shoulder muscles (BM) and pork shoulder muscles (PM), respectively. The total volatile flavour concentration of CB (4828 μg/kg sample) was three times higher than that observed for CM (1604 μg/kg sample). In BB and PB, the total volatile concentration was lower than that observed for their muscle counterparts. Aldehydes, alcohols and nitrogen- and/or sulphur-containing compounds dominated the volatile flavour profiles of CM, BM and PM while a marked dominance of alcohols was evident for CB and BB. The concentration of aldehydes in BB and PB was lower by about 66 and 70%, respectively, than that evident for the corresponding cooked muscles. The difference between the concentration of aldehydes in CM and CB was ∼7%. These differences between the volatile flavour profiles of cooked muscle samples and the corresponding by-product blends may be attributed to the compositional differences in aroma precursors in the samples. This study demonstrated that the volatile flavour compounds in cooked meat by-products are recoverable, but a careful blending of different by-products of a particular species in appropriate proportions may be necessary to generate an aroma similar to that of the respective cooked muscles.

β-Glucan extracts inhibit the in vitro intestinal uptake of long-chain fatty acids and cholesterol and down-regulate genes involved in lipogenesis and lipid transport in rats

BACKGROUND Dietary fiber reduces the intestinal absorption of nutrients and the blood concentrations of cholesterol and triglycerides. AIM We wished to test the hypothesis that high-viscosity (HV) and low-viscosity preparations of barley and oat beta-glucan modify the expression of selected genes of lipid-binding proteins in the intestinal mucosa and reduce the intestinal in vitro uptake of lipids. METHODS Five different beta-glucan extracts were separately added to test solutions at concentrations of 0.1-0.5% (wt/wt), and the in vitro intestinal uptake of lipids into the intestine of rats was assessed. An intestinal cell line was used to determine the effect of beta-glucan extracts on the expression of intestinal genes involved in lipid metabolism and fatty acid transport. RESULTS All extracts reduced the uptake of 18:2 when the effective resistance of the unstirred water layer was high. When the unstirred layer resistance was low, the HV oat beta-glucan extract reduced jejunal 18:2 uptake, while most extracts reduced ileal 18:2 uptake. Ileal 18:0 uptake was reduced by the HV barley extract, while both jejunal and ileal cholesterol uptakes were reduced by the medium-purity HV barley extract. The inhibitory effect of HV barley beta-glucan on 18:0 and 18:2 uptake was more pronounced at higher fatty acid concentrations. The expression of genes involved in fatty acid synthesis and cholesterol metabolism was down-regulated with the HV beta-glucan extracts. beta-Glucan extracts also reduced intestinal fatty-acid-binding protein and fatty acid transport protein 4 mRNA. CONCLUSIONS The reduced intestinal fatty acid uptake observed with beta-glucan is associated with inhibition of genes regulating intestinal uptake and synthesis of lipids. The inhibitory effect of beta-glucan on intestinal lipid uptake raises the possibility of their selective use to reduce their intestinal absorption.

Starch from Alberta potatoes: wet-isolation and some physicochemical properties

Starch content of six varieties of Alberta-grown potato tubers was more than 16% (wet basis). The tubers were wet fractionated in the laboratory and starch was recovered. The starch recovery ranged from 61 to 67%. The composition of the potato juice/fruit water (dry matter, protein, ash and mineral content) and starch isolations (moisture, starch, protein, lipid, ash, phosphorous and amylose content) was determined. The physicochemical characterization of the potato starch isolations were done in terms of granule size distribution, crystallinity (X-ray diffractometry), gelatinization (differential scanning calorimetry) properties, swelling factor and the changes in viscosity during heating and cooling of starch-water slurry (Brabender viscography). Substantial differences in the starch content of the tubers, fruit water composition and starch physicochemical properties were observed between potato varieties.

Dextrinization of Starch in Barley Flours with Thermostable alpha-Amylase by Extrusion Cooking

Barley grains from two hull-less varieties, Phoenix and CDC-Candle, were extruded in a twin-screw extruder at 90—140 °C, 20—50% moisture, and 0—4% α-amylase concentration. The effects of extrusion conditions on degree of hydrolysis, dextrose equivalent and mono/di/oligosaccharide composition of the dextrinized flour were determined. The data showed that degree of hydrolysis and dextrose equivalent increased with increasing α-amylase concentration and moisture level. The optimum processing temperature was 100 °C to maximize α-amylase activity while minimizing its inactivation.

Effect of Extrusion Cooking on the Primary Structure and Water Solubility of β-Glucans from Regular and Waxy Barley

ABSTRACT Water-soluble β-glucan from native and extrusion-cooked barley flours of two barley cultivars, Candle (a waxy starch barley) and Phoenix (a regular starch barley), was isolated and purified. The purity of β-glucan samples was 85–93% (w/w, dry weight basis) for Candle and 77–86% (w/w, dry weight basis) for Phoenix. The water solubility of β-glucan (at room temperature, 25°C) in the native and extruded flours (primary solubility) was different from that of the purified β-glucan samples (secondary solubility). The solubility of β-glucan in the native and extruded Candle flour was substantially higher than that of β-glucan in Phoenix. For both cultivars, β-glucan in the extruded flours had solubility (primary solubility) values higher than in their native counterparts. The solubility of β-glucan in the purified β-glucan samples differed depending on the barley cultivar and the extrusion conditions employed. The glycosidic linkage profiles of purified soluble β-glucan from native and extruded barley f...

Distribution of Granule Channels, Protein, and Phospholipid in Triticale and Corn Starches as Revealed by Confocal Laser Scanning Microscopy

ABSTRACT The morphology and microstructure of starch granules from two cultivars of triticale and from normal corn were characterized using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Compared to numerous pores distributed randomly on the surfaces of corn starch granules, markedly fewer pores were observed on the surfaces of starch granules isolated from Pronghorn triticale, and even fewer on the surfaces of starch granules isolated from Ultima triticale. CLSM with fluorescence staining revealed that starch-associated protein was predominately distributed on the granule surface and in the internal channels of both triticale and corn starches. However, after triticale starch was treated with SDS or SO2, the radially oriented, protein-filled internal channels of the granules were observed more frequently and extended to the central region of granules. Phospholipid was located mainly on the granule surface but also in channels and throughout granules in triticale starche...

Phenolic acids in some cereal grains and their inhibitory effect on starch liquefaction and saccharification.

The presence of phenolic acids in cereal grain is thought to influence starch hydrolysis during liquefaction and saccharification of grain flours in the bioethanol industry. As a basis for remodeling starch hydrolysis systems and understanding inhibition mechanisms, the composition and concentration of phenolic acids in whole grain flours of triticale, wheat, barley, and corn were analyzed by high-performance liquid chromatography. The total phenolic acid contents (sum of nine phenolic acids) in the four grains were 1.14, 1.70, 0.90, and 1.25 mg/g, respectively, with more than 90% found in the bound form. Ferulic, coumaric, and protocatechuic acids were the major phenolic acids in triticale and wheat. Gallic acid was also rich in triticale. Ferulic, coumaric, hydroxybenzoic, and gallic acids were predominant in barley. In corn, ferulic, coumaric, gallic, and syringic acids were abundant. On the basis of these profiles, pure phenolic acids were added individually and collectively to isolated starches at amounts either equivalent to or 3 times those in the whole grains for hydrolysis. The degree of starch hydrolysis with α-amylase and amyloglucosidase decreased up to 8% when individual phenolic acids were present in cooked starch slurry. The decreases were more pronounced when phenolic acids were added collectively (4-5% with α-amylase and 9-13% with sequential α-amylase and amyloglucosidase). The study of a phenolic acid-starch-enzyme model system indicated that the interactions of phenolic acid-enzyme and phenolic acid-starch significantly contributed to the inhibitory effect of starch hydrolysis. Heating facilitated the interactions. Phenolic acids thus play a significant role in the resistance of starch to enzyme and/or the loss of enzyme activity during starch hydrolysis.

Starch from hull-less barley: Ultrastructure and distribution of granule-bound proteins

ABSTRACT Starch granules isolated from waxy, normal, and high-amylose hullless barley grains were examined by transmission electron microscopy with cytochemical techniques. The micrographs showed two distinct regions of different sizes: 1) densely packed granule growth rings (which varied in size and number depending on the genotype), and 2) a loose filamentous network located in the central region of the granule. The granule ring width decreased with increasing amylose content. In all three genotypes, the growth rings closer to the granule surface were narrower in width than those within the granule interior. The waxy starch had wider intercrystalline amorphous growth rings, semicrystalline growth rings, and more open crystalline lamellae than normal and high-amylose starches. Granule bound proteins (mainly integral proteins) were located in the central and peripheral (growth ring) regions of the granule.