Lower Final Viscosity Research Articles

Extraction of starch from hulled and hull-less barley with papain and aqueous sodium hydroxide.

Starch was isolated from hulled (VJM 201) and hull-less (BL 134) barley with papain and aqueous sodium hydroxide treatments. For enzyme-assisted extraction, barley was steeped in water containing 0.2% SO2 + 0.55% lactic acid at 50° ± 2°C for 4-5h. The slurry was mixed with 0.4-2.0g papain/kg barley and incubated at 50° ± 2°C for 1-5h. Aqueous sodium hydroxide (0.01-0.05M) was added to the finely ground barley meal. The alkaline slurry was incubated at ambient temperature (25° ± 2°C) for 15-60min. The starch and grain fractions were isolated by screening and centrifugation. Increases in the time of treatment significantly affected the fiber, centrifugation and non-starch residue losses. Concentration of papain and sodium hydroxide had negligible effect on extraction losses. The enzyme-assisted extraction efficiency of starch was higher (80.7-84.6%) than the alkaline method (70.9-83.7%). The hulled barley showed higher extraction efficiency than the hull-less barley. The slurry treated with 0.4g papain/kg barley for 5h and 0.03M sodium hydroxide for 60min produced maximal yield of starch. Barley starch showed desirably high pasting temperature, water binding capacity and hold viscosity; and low final and setback viscosity compared with the commercial corn starch. The alkaline extracted hull-less barley starch showed exceptionally high peak and hold viscosities.

Relationships between starch pasting properties, free fatty acids and amylose content in barley

Relatively few studies have examined the influence of lipids or fatty acids on starch pasting properties in barley. The aim of this study was to evaluate the use of the Rapid Visco Analyser (RVA) as a tool to examine changes in starch functionality related with free fatty acids (FFAs) and amylose content in barley flour samples. Changes in RVA parameters such as setback (STB) and final viscosity (FV) were related to differences in both FFA (oleic and palmitic acids) and amylose contents due to the diverse barley genotypes analysed. The magnitude of the RVA profile values derived from samples having high a concentration of palmitic acid (3900mg/g) was lower compared with that having the lower concentration of the same FFA (2470mg/g), displaying low FV (5666 vs 4166cP) and low STB (1625 vs 1174cP) values. Similar trends were observed for the other FFA measured. These results showed that pasting properties of barley measured using RVA are determined by a complexity of parameters, where the combination of lipids (FFA) and amylose might determine the characteristics of the material and its final use (e.g. malting).

Development and characterization of extruded snacks from New Zealand Taewa (Maori potato) flours

Abstract Crispy extruded snacks were prepared by mixing ungelatinized dried potato flours from four different Taewa cultivars and a modern potato cultivar with corn flour at two different ratios (25:75; 50:50), and their quality characteristics studied. All of the potato flours showed differences in colour, dry matter content, starch content and pasting characteristics. Among the extrudates prepared with 25% potato flours, Huakaroro snacks showed an L∗ value of 51.71, whereas pure corn flour snacks had the highest L∗ value of 61.22. The b∗ at both levels of potato flour incorporation were lowest for Tutaekuri snacks. The microstructural characteristics of the extrudates such as cell structure and cell wall thickness changed considerably when potato flour was incorporated (50%) in the extruder feed. Moemoe, Tutaekuri and 100% corn flour snacks had the highest toughness, whereas the highest crispness was observed for the Huakaroro snacks. Lower and higher cold peak viscosities of 91 and 597 cP were observed for corn and Tutaekuri extrudates (in powdered form), respectively. The extrudates with 50% potato flour had higher breakdown and lower final viscosity than those containing 25% flour. The peak G′ values were highest for 100% corn, Moemoe and Karuparera snack pastes.

Physicochemical Characteristics of Starches of Two Sets of Near‐isogenic Wheat Lines with Different Amylose Content

AbstractWheat lines with modified amylose content were produced by controlling the null alleles of three homoeologous Wx loci, Wx‐A1, Wx‐B1 and Wx‐D1 and those with triple‐null Wx alleles were found to yield waxy, amylose‐free starch. In this study, the new near‐isogenic lines developed by the recurrent backcross method between cv. Kanto 107 and the waxy mutant lines, K107Wx1 or K107Wx2, were cultivated and the physicochemical characteristics of their starches were investigated. The apparent amylose contents of the waxy near‐isogenic lines were 1.6 – 3.8%, whereas those of the non‐waxy near‐isogenic lines were 23.2 – 25.4%. The waxy lines had higher gelatinization temperature and enthalpy than the non‐waxy lines and no peak of amylose‐lipid complex as determined by DSC. The X‐ray diffraction patterns from both waxy and non‐waxy near‐isogenic lines corresponded to A‐type crystallization, like their parent lines. The starches isolated from the waxy lines had lower pasting onset and peak temperatures, higher peak viscosities and breakdown and lower final viscosity than those of the non‐waxy lines in the Viscoamylograph. The starch of non‐waxy near‐isogenic lines had lower peak and final viscosities and higher breakdown than did the recurrent parent line, cv. Kanto 107. The characteristics of the new wheat starches were well understood and classified, which will contribute to the wide application of these starches in food processing.

Dough Properties and Baking Quality of Several Domestic Wheat Flours as Compared with Commercial Foreign Wheat Flour

The qualities of flours milled from various kinds of wheats (Norin 61, Hokushin, Nebarigoshi and Haruibuki) grown in Japan were studied for application to breadmaking. Protein contents of these wheat flours were in the range of 7.2 ∼ 10.0%, lower than that of a commercial hard-type wheat flour, Cameria (12.4%). Norin 61, Hokushin and Nebarigoshi had higher peak viscosity and breakdown, lower final viscosi-ties and setback than those of Cameria, while Haruibuki with high amylose content (29.2%) had lower peak and final viscosities than did the others. The dough made from the domestic wheat flours had significantly lower water absorption, development and stability time than that from Cameria. Among the domestic wheat flours, Hokushin had a strong consistency of dough for stretching than the others. In contrast, Haruibuki made less extensible and firmer dough than the others. Loaf volume of bread baked from the domestic wheat flours was considerably lower than that from Cameria. Also, the firmness of bread from the domestic wheat flours was significantly higher than that of Cameria after baking and during storage for 5 days. Among the domestic wheat flours, Hokushin exhibited good dough strength and big loaf volume of bread. In contrast, the present flour of Haruibuki was found to have inferior dough and breadmaking qualities.

Effects of Starch Isolation, Drying, and Grinding Techniques on Its Gelatinization and Retrogradation Properties

ABSTRACTThe effects of two different methods of starch isolation, drying, and grinding on gelatinization and retrogradation properties were investigated. Starch was isolated from whole wheat and flour of four hard red spring wheat cultivars. Portions of each starch isolate were freeze‐dried or air‐dried and portions of each dried starch were ground using a mortar and pestle or a Wiley Jr. mill. Less starch damage was obtained for freeze‐dried starch regardless of isolation method or grinding technique and for all starches derived from whole wheat. Highest starch damage was obtained for air‐dried starch isolates. Wiley‐milled starch isolates showed higher water‐binding. Whole wheat starch isolates had higher peak, lower trough, and lower final viscosities, as determined by starch paste viscosity analysis, than did starch isolates derived from flour. Major effects of all treatments on differential scanning calorimetry gelatinization properties showed lower onset temperature for flour starch isolates, lower peak temperature for freeze‐dried starches, and no effects due to grinding. Endotherms of all starches after refrigerated storage and freezethaw cycling were lower than those for gelatinization.

Physicochemical Properties of Australian Flours Influencing the Texture of Yellow Alkaline Noodles

ABSTRACTFlour properties of 25 Australian wheat cultivars were examined for their relationship to alkaline noodle quality. Rapid Visco Analyzer (RVA) analyses of flours showed that RVA breakdown and final viscosity determined in both water and dilute sodium carbonate were significantly related to the alkaline noodle firmness, elasticity, and surface smoothness. Flour swelling volume (FSV) of flours was negatively correlated with alkaline noodle firmness and elasticity, and positively correlated with surface smoothness of cooked noodles. Use of a dilute sodium carbonate solution led to overall increases in both paste viscosity and FSV. High FSV and low RVA final viscosity values were associated with both the softest noodles and with cultivars containing a null allele for granule‐bound starch synthase on chromosome 4A. Flour protein content and SDS sedimentation volumes were significantly related to noodle texture. The relationship between protein content and noodle firmness was dependent on the Null4A status of the flours and suggested an interaction between starch and protein in determining noodle texture. Multiple regression analysis using flour protein and FSV accounted for 76% of the variation in alkaline noodle firmness. A speculative model of noodle structure was developed based on a concept of the cooked noodle as a composite material.

Sources of Variation for Starch Gelatinization, Pasting, and Gelation Properties in Wheat

ABSTRACTThe starch of wheat (Triticum aestivum L.) flour affects food product quality due to the temperature‐dependent interactions of starch with water during gelatinization, pasting, and gelation. The objective of this study was to determine the fundamental basis of variation in gelatinization, pasting, and gelation of prime starch derived from seven different wheat cultivars: Kanto 107, which is a partial waxy mutant line, and six near‐isogenic lines (NILs) differing in hardness. Complete pasting curves with extended 16‐min hold at 93°C were obtained using the Rapid Visco Analyser (RVA). Apparent amylose content ranged from 17.5 to 23.5%; total amylose content ranged from 22.8 to 28.2%. Starches exhibited significant variation in onset of gelatinization. However, none of the parameters measured consistently correlated with onset or other RVA curve parameters that preceded peak paste viscosity. Peak paste viscosity varied from 190 to 323 RVA units (RVU). Higher peak, greater breakdown, lower final viscosity, negative setback, and less total setback were associated with lower apparent and total amylose contents. Each 1% reduction in apparent or total amylose content corresponded to an increase in peak viscosity of about 22 and 25 RVU, respectively, at 12% starch concentration. Of the seven U.S. cultivars, the lower amylose cultivars Penawawa and Klasic were missing the granule‐bound starch synthase (GBSS; ADPglucose starch glycosyl transferase, EC 2.4.4.21) protein associated with the Waxy gene locus on chromosome 4A (Wx‐B1 locus). Kanto 107 was confirmed as missing both the 7A and 4A waxy proteins (Wx‐A1 and Wx‐B1 loci). The hardness NIL also were shown to be null at the 4A locus. Apparent and total amylose contents of prime starch generally corresponded well to the number of GBSS proteins; although the hardness NIL tended to have somewhat higher amylose contents than did the other GBSS 4A nulls. We concluded that reduced quantity of starch amylose due to decreased GBSS profoundly affects starch gelatinization, pasting, and gelation properties.

Characterization of horse plasma gelsolin

Gelsolin can be purified from horse blood plasma by treating the plasma sequentially with an anion-exchange medium in the presence and then the absence of free Ca2+. The purified gelsolin migrates as a 90-kilodalton protein on electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulfate. It has an absorption coefficient of 1.4 mL/(mg.cm) and is similar in amino acid composition to other plasma gelsolins. Horse plasma gelsolin has an intrinsic sedimentation coefficient of 4.8S and a Stokes' radius of 3.8 nm. Hydrodynamic calculations suggest it to be a rather globular protein of 75,000 relative mass, a value similar to those calculated for human and pig plasma gelsolins from their amino acid sequences. Horse plasma gelsolin is able to nucleate actin polymerization, i.e., to abolish the lag observed between the initiation of polymerization of monomeric actin by the addition of salts and the rapid elongation phase of actin filament growth. This nucleation activity also results in lower final viscosities of F-actin solutions, as the existence of a larger number of filaments in samples that contain gelsolin requires that their average length be shorter.

Time-resolved X-ray scattering study of actin polymerization from profilactin.

The polymerization of actin in solutions of purified calf spleen actin or profilactin (1-10 mg . ml-1) was followed by synchrotron radiation X-ray solution scattering. At the concentration used, polymerization of actin from profilactin or actin occurs without any lag phase. It is shown by a combination of solution scattering, model calculations and electron microscopy that contrary to the conclusions from previous viscometry studies, filaments form without any lag phase in profilactin solution but aggregate in bundles or networks. This phenomenon is independent of the method used to induce polymerization: slow temperature increase, temperature jump in the presence of polymerizing salts or fast mixing with salt. This aggregation explains the lower final viscosity levels, as compared to actin solutions, observed during the polymerization of actin from profilactin.