Oat malt as a baking ingredient – A comparative study of the impact of oat,barley and wheat malts on bread and dough properties

Oat malt is a nutritionally rich ingredient mainly used in a small number of speciality products. The aim of this study was to evaluate the suitability of oat malt in wheat baking. The effect of oat malt on bread and dough properties at levels ranging from 0.5% to 5% was studied and compared with barley and wheat malts. The addition of all malts increased loaf specific volumes. Barley and wheat malts at levels above 2.5% led to a sticky and coarse crumb, but the effect of oat malt on the crumb grain was negligible. Rheological characterisation could not explain the superior baking performance of oat malt, as it increased extensibility and decreased resistance extensively indicating weakening of the extensional properties of the gluten network. The high lipolytic activity may have compensated for the loss of dough strength by improving the surface properties of gas cells. The results show that oat malt can be used in wheat baking to improve the loaf volume and nutritional quality without the detrimental effects associated with the excess amylolytic activity of barley and wheat malts.     

Oat malt as a baking ingredient – A comparative study of the impact of oat,barley and wheat malts on bread and dough properties

Oat malt is a nutritionally rich ingredient mainly used in a small number of speciality products. The aim of this study was to evaluate the suitability of oat malt in wheat baking. The effect of oat malt on bread and dough properties at levels ranging from 0.5% to 5% was studied and compared with barley and wheat malts. The addition of all malts increased loaf specific volumes. Barley and wheat malts at levels above 2.5% led to a sticky and coarse crumb, but the effect of oat malt on the crumb grain was negligible. Rheological characterisation could not explain the superior baking performance of oat malt, as it increased extensibility and decreased resistance extensively indicating weakening of the extensional properties of the gluten network. The high lipolytic activity may have compensated for the loss of dough strength by improving the surface properties of gas cells. The results show that oat malt can be used in wheat baking to improve the loaf volume and nutritional quality without the detrimental effects associated with the excess amylolytic activity of barley and wheat malts.     

Long-term frozen storage of wheat bread and dough – Effect of time,temperature and fibre on sensory quality,microstructure and state of water

The objective of this study was to determine effect of storage time, storage temperature and addition of fibre on sensory quality, state of water, microstructure and texture of bread and dough.     

Use of the hormone-biosynthesis inhibitors fluridone and paclobutrazol to determine the effects of altered abscisic acid and gibberellin levels on pre-maturity α-amylase formation in wheat grains

During germination of cereal grain, α-amylase formation is known to be inhibited by abscisic acid (ABA) and stimulated by gibberellins (GA). The role of these hormones in pre-maturity α-amylase (PMA) formation in wheat grains is less well understood. Our previous work with ABA and GA exogenously applied to grains demonstrated a clear stimulatory effect of GA, with little effect of ABA. Here, in glasshouse experiments, fluridone (ABA biosynthesis inhibitor; FD [20 μM]) or paclobutrazol (GA biosynthesis inhibitor; PB [20 μM]) were applied to intact, developing grains of the PMA-susceptible variety Rialto at 480 days after anthesis (DAA) to assess if a reduction in endogenous ABA and/or GA alters PMA formation. The experiments were conducted under non-PMA-inducing (ambient) and PMA-inducing (cold-shock) conditions. In solvent-only treated grains, a cold-shock significantly reduced the ABA content but increased GA and α-amylase activity. FD increased GA levels and α-amylase activity under ambient conditions, but decreased GA levels and α-amylase activity under cold-shock conditions, with no effect on ABA levels under either condition. PB had no effect under ambient conditions, but reduced GA levels and α-amylase under cold-shock conditions. These results indicate an association between GA levels at mid-grain development and PMA formation in wheat.     

Inhibitory Activity of Cinnamon Bark Species and their Combination Effect with Acarbose against Intestinal α-glucosidase and Pancreatic α-amylase

Inhibition of α-glucosidase and pancreatic α-amylase is one of the therapeutic approaches for delaying carbohydrate digestion, resulting in reduced postprandial glucose. The aim of this study was to evaluate the phytochemical analysis and the inhibitory effect of various cinnamon bark species against intestinal α-glucosidase and pancreatic α-amylase. The results showed that the content of total phenolic, flavonoid, and condensed tannin ranged from 0.17 to 0.21 g gallic acid equivalent/g extract, from 48.85 to 65.52 mg quercetin equivalent/g extract, and from 0.12 to 0.15 g catechin equivalent/g extract, respectively. The HPLC fingerprints of each cinnamon species were established. Among cinnamon species, Thai cinnamon extract was the most potent inhibitor against the intestinal maltase with the IC₅₀ values of 0.58 ± 0.01 mg/ml. The findings also showed that Ceylon cinnamon was the most effective intestinal sucrase and pancreatic α-amylase inhibitor with the IC₅₀ values of 0.42 ± 0.02 and 1.23 ± 0.02 mg/ml, respectively. In addition, cinnamon extracts produced additive inhibition against intestinal α-glucosidase and pancreatic α-amylase when combined with acarbose. These results suggest that cinnamon bark extracts may be potentially useful for the control of postprandial glucose in diabetic patients through inhibition of intestinal α-glucosidase and pancreatic α-amylase.     

Wheat flour enriched with oat β-glucan: A study of hydration,rheological and fermentation properties of dough

The objective of this study was to evaluate the effects of the incorporation of oat β-glucan (OβG) on the hydration, rheological and fermentation properties of wheat flour dough. Wheat flour was substituted with OβG at levels varying from 1 g/100 g–5 g/100 g. The addition of OβG significantly increased water absorption and dough development time. The dilution effect of OβG, competing for water and interaction between OβG and gluten proteins, deteriorated the gluten network structure and reduced the stability of dough. Rheological evaluation revealed an increasing tendency to solid-like behavior with increasing addition of OβG. Regarding dough fermentation properties, OβG had no effect on yeast activity but reduced the gas retention capacity of dough. Our findings indicate that OβG is a key component that determines the properties of dough, and excess OβG exhibited poorer processing characteristics compared with control.     

Elongation and insolubilisation of α-glucans by the action of Neisseria polysaccharea amylosucrase

Amylosucrase (E.C. 2.4.1.4) from Neisseria polysaccharea catalyses a transglycosylation reaction using sucrose as a glucose donor to synthesise an insoluble (1→4)-α-glucan, releasing fructose in the solution. If glycogen is used as a glucosyl unit acceptor, amylosucrase elongates polymer branches from their non-reducing ends. Testing of a large series of acceptors with various molar masses, glycosidic linkages, branching degrees and solubilities showed that chain elongation occurred only on polymers with (1→4)-α- or (1→4)-α- and (1→6)-α- linkages. Synthesis yields were better for completely soluble polymers (1.45 glucosyl units grafted per glucosyl unit for polymers with (1→4)-α- and (1→6)-α- linkages), than for partially soluble polymers (0.27–0.97 glucosyl units grafted per glucosyl unit for polymers with either (1→4)-α- linkages or (1→4)-α- and (1→6)-α- linkages). Elongation occurred randomly at the non-reducing ends of some external chains. Elongation of soluble branched molecules led to rapid gel formation favourable to gelation control inside suspensions and solutions. These polymers showed resistant starch contents (22% (w/w) to 57%) after elongation with amylosucrase.     

Genetic analysis of grain protein content,grain hardness and dough rheology in a hard×hard bread wheat progeny

Kernel texture (hard vs soft grain) and more subtle within-class variations are known to have a large influence on end-use properties, mostly through the proportion of damaged starch and subsequent water requirement. In this study, quantitative trait loci (QTL) affecting kernel texture and dough rheology in a progeny from a cross between two ‘medium-hard’ wheat cultivars were identified and compared to the QTL locations for both traits. One hundred and sixty-five F₇ recombinant inbred lines were studied in three environments in 1999. Kernel texture was estimated by both near infrared reflectance (NIR: Hard_NIR) and the single-kernel characterisation system (SKCS: Hard_SKCS). Dough rheology, taken as a predictor of end-use quality, was estimated by the empirical parameters measured by Chopin alveograph. The genetic map for this population consisted of 254 loci quite evenly distributed over the wheat genome. Considering only the QTL which were stable (detected in the three locations) and robust (through bootstrap resampling), five genomic regions were found to influence Hard_NIR, but only two of them are significant for Hard_SKCS, which was probably due to a less representative measure of the phenomenon. Eight QTLs were found for rheological traits. Some QTLs for dough rheology co-located with those for hardness or grain protein content, particularly on chromosomes 3A and 5B and close to the unlinked marker Xgwm130. According to trait, individual QTLs explained from 5.4 to 26.6% of the phenotypic variation and when taken together up to 46.0% of the variation.     

Studies on the influence of temperature,relative humidity and microenvironment on the natural fermentation of African oil bean seeds to ‘Ugba’

Studies on the enhancement of the traditional production of Ugba (a protein-rich fermented food) from African oil bean seeds were undertaken by fermenting the bean seeds at different temperatures, relative humidities (RH) and microenvironments. Fermentation was monitored by pH, texture, amino-nitrogen content and the viable cell count of the substrate. The 40 °C, 98% RH or the 130 m high density polyethylene (HDPE) treatment increased the fermentation microflora from ca. 106 CFU/g to ca. 108 CFU/g with high initial changes in pH (5.8–ca. 7.9) and texture (2.0 kg/cm2 to between 1.4 kg/cm2 and 0.9 kg/cm2) in 24 hours. Products with amino-nitrogen contents of between 12.00 mg N/100 g dry matter and 14.00 mg N/100 g dry matter were obtained in 3 days. The cell count of the 30 °C, 80% RH or 70 m treatment increased from 106 CFU/g to ca. 107 CFU/g and the pH increased from 5.8 to about 6.7 with a coincident decrease in the texture value from 2.0 kg/cm2 to about 1.7 kg/cm2 in 24 hours. Products with amino-nitrogen contents between 15.00 mg N/100 g dry matter and 19.2 mg N/100 g dry matter were obtained after 3 days. Changes in the fermentation indicators were not significant at p0.05 (pH and texture) and at p0.01 (amino-nitrogen) after 3 days for the 25 °C, 59.9% RH or 50 m low density polyethylene (LDPE) treatment. Products of fermentation at the combined optimal conditions (80% RH, 35 °C and 70 m HDPE) compared very well with the traditionally fermented products in terms of pH, texture and amino-nitrogen content.     

Studies on bioactivities of tea (Camellia sinensis L.) fruit peel extracts: Antioxidant activity and inhibitory potential against α-glucosidase and α-amylase in vitro

Tea fruit peel is the main byproduct during manufacture of tea seed oil. The great increase in tea seed oil production in recent years brings the challenge of finding application for tea fruit peel. The aims of this study were to obtain tea fruit peel extracts enriched with bioactive compounds by several solvent extraction methods and to evaluate their antioxidant activity and inhibitory potential against α-glucosidase and α-amylase in vitro. Flavonoids and phenolics were accumulated in ethyl acetate, butanol, and chloroform fractions, and these fractions possessed much better antioxidant activities, including scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) cation radicals (ABTS⁺), and reducing activity, compared with those of the 75% ethanol extract and water fraction. Moreover, the ethyl acetate, butanol, and chloroform fractions exhibited excellent inhibitory activity against α-glucosidase, much stronger than that of the positive control (acarbose). These fractions also showed mild inhibition on α-amylase activity.     

Synthesis and α-glucosidase inhibitory mechanisms of bis(2,3-dibromo-4,5-dihydroxybenzyl) ether, a potential marine bromophenol α-glucosidase inhibitor

Bis(2,3-dibromo-4,5-dihydroxybenzyl) ether (BDDE), derived from the marine algae, is a potential α-glucosidase inhibitor for type 2 diabetes treatment. In the present study, a synthetic route was established as a valid approach to obtain BDDE. Fluorescence spectra, circular dichroism spectra and molecular docking methods were employed to elucidate the inhibitory mechanisms of BDDE against α-glucosidase. The results showed that BDDE could be prepared effectively and efficiently with the established synthetic methods. Synthetic BDDE bound with α-glucosidase and induced minor conformational changes of the enzyme. The docking results indicated the interaction between BDDE and α-glucosidase was driven by both hydrophobic forces and hydrogen bonds. The docked BDDE molecule was completely buried in the α-glucosidase binding pocket with part of the molecule reaching the catalytic center and overlapping with the position of glucose, and the rest of the molecule extending towards protein surface. This study provides useful information for the understanding of the BDDE-α-glucosidase interaction and for the development of novel α-glucosidase inhibitors.     

Inhibition study of red rice polyphenols on pancreatic α-amylase activity by kinetic analysis and molecular docking

This study sought to investigate the possible inhibition mechanism of red rice polyphenols (RRP) on pancreatic α-amylase (PA) activity. RRP showed strong inhibition against PA activity and the half-inhibitory concentration (IC₅₀) value was 3.61 μg/mL. The fluorescence quenching of PA by RRP was a combination of static quenching and dynamic quenching. RRP could aggregate with PA and the physiochemical properties of the aggregates were closely related to the concentration of RRP. Kinetic analysis suggested that the inhibition mode of RRP on PA was reversible inhibition, which was a mixing of competitive inhibition and noncompetitive inhibition. Molecular docking speculated that RRP could form hydrogen bonds with PA by binding to the catalytic active sites (ASP197, GLU233 and ASP300) and the microenvironments of TRP58 and TRP59 were altered, thus inhibiting PA activity.     

Effect of extrusion cooking of sorghum flour on rheology,morphology and heating rate of sorghum–wheat composite dough

Addition of a gluten-free flour such as sorghum has negative impact on the quality of wheat dough for bread making. One of the methods which can be used to promote the quality of sorghum-wheat composite dough is to extrude the sorghum flour before incorporation. In this regard, to produce a dough with appropriate bakery properties sorghum flour was extruded at 110 °C and 160 °C die temperature with 10%, 14% and 18% feed moisture. The effect of extruded sorghum flour incorporation (10%) on rheological (farinography and stress relaxation behavior), morphological and temperature profile of sorghum-wheat composite dough were evaluated. Extrusion cooking altered the sorghum-wheat composite dough properties through partial gelatinization of starch granules. Addition of extruded sorghum flour increased the water absorption and dough development time but it decreased the dough stability. Native sorghum-wheat composite dough showed viscoelastic liquid-like behavior whereas addition of sorghum flour extrudate changed dough to a more viscoelastic solid-like structure. Maxwell model was more appropriate than Peleg model to describe the viscoelasticity of the sorghum-wheat composite dough. Extrusion cooking decreased composite dough elasticity and viscosity. Sorghum extrudate increased the heating rate of composite dough crumb during baking. Addition of extruded sorghum flour formed a non-uniform and less compact dough structure. As a result, dough containing extruded sorghum flour had a good potential for producing a high-yielding bread in a short time of baking.     

Biological and chemical evaluation of chick pea seed proteins as affected by germination,extraction and α-amylase treatment

The effects of germination, extraction (double extraction with 70% ethanol and water at isoelectric point) and -amylase treatments of chick pea seed flours on crude protein, total carbohydrate, protein efficiency ratio (PER), biological value (BV), true digestibility (TD), net protein utilization (NPU), essential amino acid composition, in-vitro protein digestibility (IVPD) and actual amino acid indices (essential amino acid index or amino acid score) were evaluated. Crude protein content was increased (8–149%), while total carbohydrate was decreased (11–62%) by germination, extraction and -amylase treatments. Alpha-amylase treatment was more efficient in reducing total carbohydrate and increasing the protein content than that of extraction treatment. The protein quality of chick pea flours as measured by PER, BV, TD, NPU, IVPD and corrected amino acid indices (actual amino acid indices×IVPD) was significantly improved by these treatments. The protein quality of germinated--amylase treatment was comparble with casein, while germinated--amylase treaded seeds appeared nutritionally superior to casein. The results indicate that the germinated--amylase and germinated--amylase-extracted treatments could be used successfully as a source of concentrated high quality protein for baby food production. The corrected amino acid indices gave better prediction of PER, BV, TD and NPU (r=93 to 97) than actual amino acid indices (r=45 to 71). PER was highly correlated with corrected amino acid score (r=0.93). The PER could be predicted from the following simple regression equation: PER=–1.827+0.0561×corrected amino acid score.     

The impact of heating and cooling on the physico-chemical properties of wheat gluten–water suspensions

The rapid visco analysis (RVA) system was used to measure rheological behaviour in 20% (w/v) gluten-in-water suspensions upon applying temperature profiles. The temperature profiles included a linear temperature increase, a holding step, a cooling step with a linear temperature decrease to 50 °C, and a final holding step at 50 °C. Temperature and duration of the holding phase both affected RVA viscosity and protein extractability. Size-exclusion and reversed-phase HPLC showed that increasing the temperature (up to 95 °C) mainly decreased glutenin extractability. Holding at 95 °C resulted in polymerisation of both gliadin and glutenin. Above 80 °C, the RVA viscosity steadily increased with longer holding times while the gliadin and glutenin extractabilities decreased. Their reduced extractability in 60% ethanol showed that γ-gliadins were more affected after heating than α-gliadins and ω-gliadins. Enrichment of wheat gluten in either gliadin or glutenin showed that both gliadin and glutenin are necessary for the initial viscosity in the RVA profile. The formation of polymers through disulphide bonding caused a viscosity rise in the RVA profile. The amounts of free sulphydryl groups markedly decreased between 70 and 80 °C and when holding the temperature at 95 °C.     

Molecular weight and structure units of (1→3, 1→4)-β-glucans in dough and bread made from hull-less barley milling fractions

Milling fractions of hull-less barley, and dough and bread with hull-less barley flour (40%) and wheat flour (60%) were analysed in an investigation of how the properties of (1→3, 1→4)-β-glucan were affected by milling, dough formation and bread making. Calcofluor average molecular weight $({\overline{M}}_{\text{cf}})$ and molecular weight distribution and the cellotriosyl/cellotetraosyl ratio of the (1→3, 1→4)-β-glucan were determined. Four different hull-less barley samples were milled to produce straight-run white flours, shorts, bran and whole-meal flours. The molecular weight distributions were unimodal for all fractions, and the $({\overline{M}}_{\text{cf}})$ range was between 117×10⁴ and 188×10⁴. These parameters were similar for all barleys, although $({\overline{M}}_{\text{cf}})$ was somewhat lower in white flour and bran fractions and somewhat higher in shorts and whole-meal. The cellotriosyl/cellotetraosyl ratio (1.5–1.8) was also similar in all fractions. Doughs and breads were made to study how flour type (sifted or whole-meal barley flour), water content, yeast, mixing time and fermentation time affect (1→3, 1→4)-β-glucan. The molecular weight distribution of (1→3, 1→4)-β-glucan was polymodal with two or three populations for all doughs and breads, and the $({\overline{M}}_{\text{cf}})$ decreased with increasing mixing and fermentation time. These results indicated that (1→3, 1→4)-β-glucan was degraded by endogenous β-glucanases in the barley and/or wheat flour. The molecular weight was not significantly affected by bread-baking and other factors. After mixing and fermentation the cellotriosyl/cellotetraosyl ratio was about 1.7–1.8 and was thus not significantly different from that of the flour blends. Thus to retain high molecular weight (1→3, 1→4)-β-glucan, which is important for its cholesterol-lowering effect, it is thus important to keep the mixing and fermentation time as short as possible when baking hull-less barley bread.     

Effects of S3307 on the photosynthesis,the activity of SOD,and MDA content of rice flag leaf

Ｕｎｉｃｏｎａｚｏｌ，（Ｅ）＿１＿（４＿ｃｈｌｏｒｏｐｈｅｎｙｌ）＿４，４＿ｄｉｍｅｔｈｙｌ＿２（１，２，４＿ｔｒｉａｚｏｌ＿ｌ＿ｙｌ）＿１＿ｐｅｎｔｅｎ＿３＿０１，ｎａｍｅｄＳ３３０７，ｉｓａｎｅｗｐｌａｎｔｇｒｏｗｔｈｒｅｔａｒｄａｎｔｔｈａｔｃａｎｒｅｔａｒｄｔｈｅ ｇｒｏｗｔｈｏｆ ｐｌａｎｔｓ，ｍａｋｅ ｐｌａｎｔｄｗａｒｆ，ｐｒｏｍｏｔｅｒｏｏｔａｎｄｔｉｌｌｅｒｇｒｏｗｔｈ，ｄｅｌａｙｔｈｅｓｅｎｅｓｃｅｎｃｅｏｆｌｅａｖｅｓ，ａｎｄｉｎｃｒｅａｓｅｔｈｅｎｅｔｐｈｏｔｏ ｓｙｎｔｈｅ…     

The Effect of Ca2+-Ions on the α-Amylolysis of Granular Starches from Oats and Waxy-Maize

Granular oat starch was subjected to hydrolysis withBacillus subtilis alpha-amylase in either calcium acetate or sodium acetate buffer and compared with the hydrolysis of waxy-maize starch granules. The enzyme was pumped through a thin layer of starch packed into a special column and further into an ion-exchanger that retained the enzyme but not the dextrins solubilised from the granules. Both the amylose and the amylopectin components of oat starch granules were attacked by the enzyme. Calcium ions increased the rate of solubilisation of the oat starch granules but not of the waxy-maize starch granules. However, the composition of the solubilised dextrins was clearly affected with both types of granules so that the molecular weight distribution of the products shifted to smaller sizes in the presence of calcium. Other salts that were tested with the oat starch granules did not affect the solubilisation rate. Scanning electron micrographs showed that the attack pattern ofalpha-amylase on oat starch is different from the attack on waxy-maize granules.