ABSTRACT Quinoa is an attractive non-animal protein source, because of its absence of gluten and ... more ABSTRACT Quinoa is an attractive non-animal protein source, because of its absence of gluten and the favorable amino-acid profile. The objective of this study was the extraction of quinoa protein by two consecutive approaches. Initially, the protein-rich bran was isolated by optimizing the conditioning parameters of a milling fractionation procedure. In contrast to the protein content of the whole grain, 11.75% in dry base (db), the bran fraction contained 27.78% (db) protein when conditioned with 15% moisture at 20°C for 20h. Subsequently, an aqueous extraction was developed, resulting in a protein solubility of 60% at pH 10 and 20 °C for 1 h. For purification at the isoelectric point, the pH-value and the separation method were varied. After drying, an extraction of proteins from bran yielded 68 % (db) as compared to 52 % (db) protein from quinoa whole grain flour.
n der Prozesskette zur Herstellung von Backwaren wird der Knetprozess als einer der wichtigsten P... more n der Prozesskette zur Herstellung von Backwaren wird der Knetprozess als einer der wichtigsten Produktionsschritte angesehen. Fehler in der Teigherstellung wirken sich daher auf die gesamte Fertigungskette bis hin zum Endprodukt aus. Primär bei der Weizenteigherstellung findet bei zu geringer Knetintensität eine beeinträchtigte Ausbildung des Glutennetzwerks statt, was wiederum ein verringertes Gebäckvolumen zur Folge haben kann. Im Gegensatz dazu weisen überknetete Teige eine Depolymerisation beziehungsweise Perforation das Glutennetzwerks auf, wodurch gleichermaßen eine Beeinträchtigung des Produktvolumens stattfinden kann. Im Falle einer maschinellen Steuerung des Knetprozesses werden üblicherweise registrierende Knetsysteme herangezogen, die der Erfassung des Energieeintrags in das Mehl-Wasser-System dienen. Die Aufzeichnung der Energieaufnahme in diesen Knetanlagenerfolgt jedoch nur annäherungsweise so präzise wie in drehmomentaufnehmenden Systemen wie zum Beispiel im Farinogr...
The kneading process is seen as the most important pro-duction step in the process flow of the pr... more The kneading process is seen as the most important pro-duction step in the process flow of the production of baked goods. Therefore, faults in the dough production affect the whole production chain including the final product. Mainly in the produc-tion of wheat dough, too low knea-ding intensity causes an impaired formation of the gluten network and this causes again a reduced volume of the baked goods. By con-trast, excessively kneaded dough shows a depolymerisation or perfo-ration of the gluten network which, in the same way, can result in an impairment of the product volu-me [1]. If the kneading process is controlled by machines, it is usual to use recording kneading systems which record the energy input into the flour -water system. Recording of the energy consumption into these kneading systems, however, is only approximately as precise as in torque measuring systems, e.g. in the Farinograph (Brabender), in the DoughLab (Perten) or in the Mixo-lab (Chopin). This means, not non-...
Any factor which impairs the development of the gluten network affects the gas retention capacity... more Any factor which impairs the development of the gluten network affects the gas retention capacity and the overall baking performance. This study aimed to examine why rising yeast concentrations (Saccharomyces cerevisiae) decrease the dough elasticity in an asymptotic manner. Since in 27 commercial fresh and dry yeasts up to 81 mg glutathione (GSH) per 1g dry sample were found. Through the addition of reduced GSH in dough without yeast, the extent of dough weakening was analysed. Indeed rheological measurements confirmed that yeast-equivalent levels of GSH had a softening effect and during 3h fermentation the weakening coefficient increased from 0.3% to 20.4% in a Rheofermentometer. The present results indicate that free -SH compounds, as represented by GSH, considerably contribute to the softening of dough through dead yeast cells.
ABSTRACT Besides an appealing texture and taste, gluten-free products should feature a well-balan... more ABSTRACT Besides an appealing texture and taste, gluten-free products should feature a well-balanced nutrient profile, since celiac disease or chronic inflammations are likely to induce malnutrition for involved patients. Due to their composition, pseudocereals represent a promising ingredient to improve nutrient profile of gluten-free bread. The objective of this study was to investigate the impact of quinoa bran on gluten-free bread quality, focusing on volume, pore size and sensory acceptance. The impact of quinoa bran was studied in a gluten-free bread formulation. Five different quinoa bran and two whole grain flour concentrations were evaluated and compared to a control formulation based on rice and corn flour. The rheological properties of quinoa bran as well as the effect on dough development up to a replacement level of 80 % were investigated. Baking tests were carried out, and loaf volume, crumb firmness and sensory characteristics were determined. Quinoa fractions significantly increased carbon dioxide formation (p < 0.05) due to a higher substrate availability. Gas retention was reduced by increasing bran levels (p < 0.05). Oscillation measurements indicated a firming impact of quinoa bran which might have caused a more permeable dough structure, promoting the release of carbon dioxide. With regard to the specific loaf volume significant differences were found across the quinoa milling fractions and the applied levels (p < 0.05). Overall this study demonstrated that 10 % bran improved the bread volume by 7.4 % and enhanced the appearance without compromising the taste.
Critical Reviews in Food Science and Nutrition, 2015
Abstract Arabinoxylan (AX) is the major non-starch polysaccharide contained in various types of g... more Abstract Arabinoxylan (AX) is the major non-starch polysaccharide contained in various types of grains. AX consists of a backbone of β‑1.4‑D-xylopyranosyl residues with randomly linked α-L-arabinofuranosyl units. Once isolated and included as food additive, AX affects foodstuff attributes and has positive effects on human health. AX can be classified into water-extractable and water-unextractable AX. For isolating AX out of their natural matrix, a range of methods was developed, adapted and improved. This review presents a survey of the commonly used extraction methods for AX by the influence of different techniques. It also provides a brief overview of the structural and technological impact of AX as a dough additive. A concluding section summarizes different detection methods for analyzing and quantification AX.
ABSTRACT As shown in previous studies the application of yeast presents a challenge for rheologic... more ABSTRACT As shown in previous studies the application of yeast presents a challenge for rheological measurements. The continuously produced metabolites of this living organism strongly influence the resulting data. In the study on hand, the method for fundamental oscillatory tests was modified to fit the needs of the flow behavior of yeasted dough. The analysis of the pH-value offered a method to indirectly determine the carbon dioxide production, as was proven by a linear correlation with the density (r2=0.88, p<0.001). As evidenced by Rheofermentometer measurements, the gas holding capacity of wheat dough was not affected by the kinetics of CO2-production, whereas the total amount of gas was decisive. Moreover, the method associated density correlated significantly (p<0.001) with the resistance to extension, the extensibility and the complex shear modulus. Finally, different yeast concentrations provoked up to 57 % higher loss factors immediately after kneading. In summary, it was proven that yeasted wheat dough was significantly more plastic and susceptible to pressure than the non-leavened models. In turn, this provides a practical and realistic insight into the structural changes of wheat dough as affected by the metabolism of Saccharomyces cerevisiae.
Journal of agricultural and food chemistry, Jan 12, 2014
The limited use of distiller's grains (DG) in the food industry depends occasionally on the c... more The limited use of distiller's grains (DG) in the food industry depends occasionally on the characteristic odor of DG. For a better understanding of this typical odor, a sensory evaluation was performed first. The impressions seasoninglike, roasty/breadlike, and malty/caramellike were revealed as the most intensive odors. Furthermore, analysis of volatile flavor compounds was applied on dried DG from wheat. Isolation was performed by means of headspace solid-phase microextraction, solvent-assisted flavor evaporation (SAFE), and simultaneous distillation/extraction and identification with gas chromatography-olfactometry/mass spectrometry. As a result, 42 odor-active compounds could be identified in total. Among 24 of the 42 odor-active compounds obtained by SAFE, 3-hydroxy-4,5-dimethyl-2(5H)-furanone (seasoninglike) showed the highest flavor dilution (FD) factor, and 7 compounds (3-methylbutanioc acid, dimethyl trisulfide, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 2-ethyl-3,5-dimeth...
ABSTRACT Quinoa is an attractive non-animal protein source, because of its absence of gluten and ... more ABSTRACT Quinoa is an attractive non-animal protein source, because of its absence of gluten and the favorable amino-acid profile. The objective of this study was the extraction of quinoa protein by two consecutive approaches. Initially, the protein-rich bran was isolated by optimizing the conditioning parameters of a milling fractionation procedure. In contrast to the protein content of the whole grain, 11.75% in dry base (db), the bran fraction contained 27.78% (db) protein when conditioned with 15% moisture at 20°C for 20h. Subsequently, an aqueous extraction was developed, resulting in a protein solubility of 60% at pH 10 and 20 °C for 1 h. For purification at the isoelectric point, the pH-value and the separation method were varied. After drying, an extraction of proteins from bran yielded 68 % (db) as compared to 52 % (db) protein from quinoa whole grain flour.
n der Prozesskette zur Herstellung von Backwaren wird der Knetprozess als einer der wichtigsten P... more n der Prozesskette zur Herstellung von Backwaren wird der Knetprozess als einer der wichtigsten Produktionsschritte angesehen. Fehler in der Teigherstellung wirken sich daher auf die gesamte Fertigungskette bis hin zum Endprodukt aus. Primär bei der Weizenteigherstellung findet bei zu geringer Knetintensität eine beeinträchtigte Ausbildung des Glutennetzwerks statt, was wiederum ein verringertes Gebäckvolumen zur Folge haben kann. Im Gegensatz dazu weisen überknetete Teige eine Depolymerisation beziehungsweise Perforation das Glutennetzwerks auf, wodurch gleichermaßen eine Beeinträchtigung des Produktvolumens stattfinden kann. Im Falle einer maschinellen Steuerung des Knetprozesses werden üblicherweise registrierende Knetsysteme herangezogen, die der Erfassung des Energieeintrags in das Mehl-Wasser-System dienen. Die Aufzeichnung der Energieaufnahme in diesen Knetanlagenerfolgt jedoch nur annäherungsweise so präzise wie in drehmomentaufnehmenden Systemen wie zum Beispiel im Farinogr...
The kneading process is seen as the most important pro-duction step in the process flow of the pr... more The kneading process is seen as the most important pro-duction step in the process flow of the production of baked goods. Therefore, faults in the dough production affect the whole production chain including the final product. Mainly in the produc-tion of wheat dough, too low knea-ding intensity causes an impaired formation of the gluten network and this causes again a reduced volume of the baked goods. By con-trast, excessively kneaded dough shows a depolymerisation or perfo-ration of the gluten network which, in the same way, can result in an impairment of the product volu-me [1]. If the kneading process is controlled by machines, it is usual to use recording kneading systems which record the energy input into the flour -water system. Recording of the energy consumption into these kneading systems, however, is only approximately as precise as in torque measuring systems, e.g. in the Farinograph (Brabender), in the DoughLab (Perten) or in the Mixo-lab (Chopin). This means, not non-...
Any factor which impairs the development of the gluten network affects the gas retention capacity... more Any factor which impairs the development of the gluten network affects the gas retention capacity and the overall baking performance. This study aimed to examine why rising yeast concentrations (Saccharomyces cerevisiae) decrease the dough elasticity in an asymptotic manner. Since in 27 commercial fresh and dry yeasts up to 81 mg glutathione (GSH) per 1g dry sample were found. Through the addition of reduced GSH in dough without yeast, the extent of dough weakening was analysed. Indeed rheological measurements confirmed that yeast-equivalent levels of GSH had a softening effect and during 3h fermentation the weakening coefficient increased from 0.3% to 20.4% in a Rheofermentometer. The present results indicate that free -SH compounds, as represented by GSH, considerably contribute to the softening of dough through dead yeast cells.
ABSTRACT Besides an appealing texture and taste, gluten-free products should feature a well-balan... more ABSTRACT Besides an appealing texture and taste, gluten-free products should feature a well-balanced nutrient profile, since celiac disease or chronic inflammations are likely to induce malnutrition for involved patients. Due to their composition, pseudocereals represent a promising ingredient to improve nutrient profile of gluten-free bread. The objective of this study was to investigate the impact of quinoa bran on gluten-free bread quality, focusing on volume, pore size and sensory acceptance. The impact of quinoa bran was studied in a gluten-free bread formulation. Five different quinoa bran and two whole grain flour concentrations were evaluated and compared to a control formulation based on rice and corn flour. The rheological properties of quinoa bran as well as the effect on dough development up to a replacement level of 80 % were investigated. Baking tests were carried out, and loaf volume, crumb firmness and sensory characteristics were determined. Quinoa fractions significantly increased carbon dioxide formation (p < 0.05) due to a higher substrate availability. Gas retention was reduced by increasing bran levels (p < 0.05). Oscillation measurements indicated a firming impact of quinoa bran which might have caused a more permeable dough structure, promoting the release of carbon dioxide. With regard to the specific loaf volume significant differences were found across the quinoa milling fractions and the applied levels (p < 0.05). Overall this study demonstrated that 10 % bran improved the bread volume by 7.4 % and enhanced the appearance without compromising the taste.
Critical Reviews in Food Science and Nutrition, 2015
Abstract Arabinoxylan (AX) is the major non-starch polysaccharide contained in various types of g... more Abstract Arabinoxylan (AX) is the major non-starch polysaccharide contained in various types of grains. AX consists of a backbone of β‑1.4‑D-xylopyranosyl residues with randomly linked α-L-arabinofuranosyl units. Once isolated and included as food additive, AX affects foodstuff attributes and has positive effects on human health. AX can be classified into water-extractable and water-unextractable AX. For isolating AX out of their natural matrix, a range of methods was developed, adapted and improved. This review presents a survey of the commonly used extraction methods for AX by the influence of different techniques. It also provides a brief overview of the structural and technological impact of AX as a dough additive. A concluding section summarizes different detection methods for analyzing and quantification AX.
ABSTRACT As shown in previous studies the application of yeast presents a challenge for rheologic... more ABSTRACT As shown in previous studies the application of yeast presents a challenge for rheological measurements. The continuously produced metabolites of this living organism strongly influence the resulting data. In the study on hand, the method for fundamental oscillatory tests was modified to fit the needs of the flow behavior of yeasted dough. The analysis of the pH-value offered a method to indirectly determine the carbon dioxide production, as was proven by a linear correlation with the density (r2=0.88, p<0.001). As evidenced by Rheofermentometer measurements, the gas holding capacity of wheat dough was not affected by the kinetics of CO2-production, whereas the total amount of gas was decisive. Moreover, the method associated density correlated significantly (p<0.001) with the resistance to extension, the extensibility and the complex shear modulus. Finally, different yeast concentrations provoked up to 57 % higher loss factors immediately after kneading. In summary, it was proven that yeasted wheat dough was significantly more plastic and susceptible to pressure than the non-leavened models. In turn, this provides a practical and realistic insight into the structural changes of wheat dough as affected by the metabolism of Saccharomyces cerevisiae.
Journal of agricultural and food chemistry, Jan 12, 2014
The limited use of distiller's grains (DG) in the food industry depends occasionally on the c... more The limited use of distiller's grains (DG) in the food industry depends occasionally on the characteristic odor of DG. For a better understanding of this typical odor, a sensory evaluation was performed first. The impressions seasoninglike, roasty/breadlike, and malty/caramellike were revealed as the most intensive odors. Furthermore, analysis of volatile flavor compounds was applied on dried DG from wheat. Isolation was performed by means of headspace solid-phase microextraction, solvent-assisted flavor evaporation (SAFE), and simultaneous distillation/extraction and identification with gas chromatography-olfactometry/mass spectrometry. As a result, 42 odor-active compounds could be identified in total. Among 24 of the 42 odor-active compounds obtained by SAFE, 3-hydroxy-4,5-dimethyl-2(5H)-furanone (seasoninglike) showed the highest flavor dilution (FD) factor, and 7 compounds (3-methylbutanioc acid, dimethyl trisulfide, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 2-ethyl-3,5-dimeth...
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