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Rheological Behaviour of Formulated Bread Doughs During Mixing and Heating

During breadmaking different physicochemical phenomena occur producing discernible changes in the rheological properties. Traditionally, these changes have been studied with equipments controlling separately the mixing step and the baking process. The MIXOLAB is a new apparatus which measures torque when bread dough is subjected to a dual mixing and temperature constraint. It was the aim of this study to compare this new tool with other available methodologies in order to explore its use as a suitable technique for determining bread dough rheological properties. A broad range of correlations was found, not only within parameters derived from the MIXOLAB, but also with standard methods as the pasting method performed by the Rapid Visco Analyser, the gluten index and uni- and bi-axial extensional measurements. The use of MIXOLAB has also allowed the identification of the influence of design factors (flour and exogenous enzymes) on the rheological properties. These results confirm MIXOLAB as a promising tool for the rheological assessment of bread dough.

Regulation of acetic acid production by homo-and heterofermentative lactobacilli in whole-wheat sour-doughs

ZusammenfassungDie Haltbarkeit von Sauerteig-Brot gegen mikrobiologische Verderbnis beruht auf seinem Säuregehalt. Als sekundäres Stoffwechselprodukt der Zuckergärung durch Milchsäurebakterien, kann die Essigsäure-Bildung von Sauerstoff- oder Wasserstoffacceptoren gefördert werden. Diese Veröffentlichung befaßt sich mit dem Einfluß von Sauerstoff und Produkten mit hohem Fructosegehalt (Rohrzucker, Invertzucker, Fructose-Sirup) auf die Essigsäure-Bildung durch hetero- (Lactobacillus brevis B-21, 25a, L-62;L. sanfrancisco L-99) und homofermentative (L. plantarum B-39) Laktobacillen in Weizenvollkornsauerteigen (TA 280 und 350). ph-Wert und Säuregrad von Sauerteigen nach 44-stündiger Gärung waren verschieden je nach TA und Stamm. Wie erwartet, verursachte die Zugabe von Sauerstoff eine größere Zunahme des Säuregrades mit heterofermentativen Laktobacillen (15–42%) als mitL. plantarum (15). Fructose-Zugabe war nur wirksam für die heterofermentativen Stämme, aber die allgemeinen Wirkungen waren kleiner als die bei der Behandlung mit Sauerstoff beobachteten. Die Fähigkeit von Laktobazillen, ohne Behandlung in Sauerteigen Essígsäure zu bilden, schwankte zwischen 0.16 g/100 g Mehl (B-39, 280, 350 TA) und 0.47–0.65% (L-62, 280, 350 TA). Die Bildung von Essigsäure wurde durch alle Behandlungen gefördert. Die Behandlung mit Sauerstoff war wieder die effizienteste zur Förderung der Essigsäurebildung; der Anstieg schwankte zwischen 54% (B-21) und 269% (L-99, 350 TA). Die Zugabe von Wasserstoffacceptoren hatte verschiedene Effekte. Reine Fructose ergab im allgemeinen größere Anstiege als Invertzucker oder Fructose Sirup. Die Haupteffekte wurden beiL. brevis 25a (280 TA), B-21 (350 TA) undL. sanfrancisco L-99 (350 TA) mit Anstiegen von 92% bis 123% nachgewiesen. Die mit L-62 (280, 350 TA) oder L-99 (350 TA) hergestellten Sauerteige (44 h, 35 °C, 150 rpm schütteln) ergaben die höchste Gehalte an Essigsäure (1.02–1.04%).AbstractThe efficiency of sour-dough as a possible preservative agent of microbial spoilage of bread depends on its acetic acid content. As a secondary metabolite of sugar fermentation by lactic acid bacteria, acetic acid may be promoted in the presence of O2 or H+ acceptors. This paper studies the influence of O2 and high fructose content products (pure sugar, invert sugar, fructose syrup) addition on acetic acid production by hetero- (Lactobacillus brevis 25a, B-21, L-62;L. sanfrancisco L-99) and homofermentative (L. plantarum B-39) lactobacilli in whole-wheat sour-doughs [280 and 250 dough yield (DY)]. The pH and total titratable acidity (TTA) of sour-doughs after 44 h fermentation varied with DY and strain. As expected, the addition of O2 promoted greater increases in TTA with heterofermentative lactobacilli (15–42%) than withL. plantarum (15%). Fructose addition was only effective for heterofermentative strains, but the overall effects were smaller than those observed for oxygenation. The ability of lactobacilli to produce acetic acid in sour-doughs without treatment varied from 0.16 g/100 g flour at 44 h (B-39, 280, 350 DY) to 0.47–0.65% (L-62, 280, 350 DY). The production of acetic acid was positively promoted by all treatments. Oxygenation was again the most effective way of inducing acetic acid production; increases ranged from 54% (B-21) to 269% (L-99, 350 DY). The addition of H+ acceptors had variable effects. Pure fructose resulted, in general, in greater increases than invert sugar of fructose syrup. The main effects were detected forL. brevis 25a (280 DY) B-21 (350 DY) andL sanfrancisco L-99 (350 DY) with increases ranging from 92 to 123%. The highest levels of acetic acid (1.02–1.04%) corresponded to sour-doughs (44 h, 35° C shaking 150 rpm) started with L-62 (280, 350 DY) or L-99 (350 DY).

Optimized separation of nonpolar and polar lipid classes from wheat flour by solid-phase extraction

A method combining solid-phase extraction on prepacked silica and aminopropyl bonded-phase (Bond-Elut) columns has been developed for the separation of neutral lipids, glycolipids and phospholipids from wheat flour into individual classes in high yield and homogeneity. Chromatography on a single silica column (500 mg) with solvent combinations of increasing polarity resulted in complete separation of steryl esters, triglycerides, free fatty acids, 1,2-diglycerides, 1,3-diglycerides, monoglycerides, monogalactosylglycerides, digalactosylglycerides, phosphatidylcholine and lysophosphatidylcholine. Chromatography on an aminopropyl bonded-phase column (500 mg) with ternary mixtures of chloroform/methanol/ammonium hydroxide led to the proper separation of N-acyl-phosphatidylethanolamine and N-acyl-lysophosphatidylethanolamine, previously coeluted on the prepacked silica column. Cross contamination among phospholipid classes tested by normal-phase high-performance liquid chromatography was always less than 14%.

Composition and distribution of individual molecular species of major glycolipids in wheat flour

The distribution of individual molecular species of the main wheat flour glycolipids, digalactosyldiglyceride (DGDG), monogalactosyldiglyceride (MGDG), digalactosylmonoglyceride (DGMG) and monogalactosylmonoglyceride (MGMG) has been investigated by reversed phase high-performance liquid chromatography of their benzoate derivatives after the respective galactosylglyceride classes were obtained by semi-preparative high-performance liquid chromatography. Combinations of linoleic acid at thesn-2 position with linoleic, oleic and palmitic acids at thesn-1 position predominated as major common molecular species of MGDG and DGDG. The pairs 16:0/20:4, 18:3/20:1, 18:0/18:3, 18:0/18:1 and 20:0/18:2 were determined only among MGDG molecular species. Five common molecular species containing 16:0, 18:0, 18:1, 18:2 and 18:3 fatty acids, respectively, were determined in MGMG and DGMG, with 18:2 being the most predominant form, and 18:1 (MGMG) and 16:0 (DGMG) as the next major fatty acids.

Gluten-free dough-making of specialty breads: Significance of blended starches, flours and additives on dough behaviour

The capability of different gluten-free (GF) basic formulations made of flour (rice, amaranth and chickpea) and starch (corn and cassava) blends, to make machinable and viscoelastic GF-doughs in absence/presence of single hydrocolloids (guar gum, locust bean and psyllium fibre), proteins (milk and egg white) and surfactants (neutral, anionic and vegetable oil) have been investigated. Macroscopic (high deformation) and macromolecular (small deformation) mechanical, viscometric (gelatinization, pasting, gelling) and thermal (gelatinization, melting, retrogradation) approaches were performed on the different matrices in order to (a) identify similarities and differences in GF-doughs in terms of a small number of rheological and thermal analytical parameters according to the formulations and (b) to assess single and interactive effects of basic ingredients and additives on GF-dough performance to achieve GF-flat breads. Larger values for the static and dynamic mechanical characteristics and higher viscometric profiles during both cooking and cooling corresponded to doughs formulated with guar gum and Psyllium fibre added to rice flour/starch and rice flour/corn starch/chickpea flour, while surfactant- and protein-formulated GF-doughs added to rice flour/starch/amaranth flour based GF-doughs exhibited intermediate and lower values for the mechanical parameters and poorer viscometric profiles. In addition, additive-free formulations exhibited higher values for the temperature of both gelatinization and retrogradation and lower enthalpies for the thermal transitions. Single addition of 10% of either chickpea flour or amaranth flour to rice flour/starch blends provided a large GF-dough hardening effect in presence of corn starch and an intermediate effect in presence of cassava starch (chickpea), and an intermediate reinforcement of GF-dough regardless the source of starch (amaranth). At macromolecular level, both chickpea and amaranth flours, singly added, determined higher values of the storage modulus, being strengthening effects more pronounced in presence of corn starch and cassava starch, respectively.

Lipid dynamics in blended wheat and non-wheat flours breadmaking matrices: Impact on fresh and aged composite breads

The use of pseudocereals, legumes and ancient grains for breadmaking applications is receiving particular attention since they involve nutrient dense grains with proven health-promoting attributes. Dilution up to 45% of the basic wheat flour matrix by accumulative ternary addition of teff, green pea and buckwheat flours did significantly impact both the extractability and distribution of lipid subfractions in composite flours, doughs and breads, and induced differentiated dynamics in lipid binding along breadmaking. During mixing, a preferential covalent lipid binding to the inside part of the starch granules takes place at the expenses of both accessible free lipids and lipids initially bound non-covalently to the gluten/non-gluten proteins and to the outside part of the starch granules. During fermentation and later baking a preferential lipid binding to the gluten/non-gluten proteins and to the outside and inside starch granules takes place at the expenses of both a free lipid displacement and a bound lipid translocation to new protein and starch active sites. It can be noticed that the larger the accumulation of both protein- and starch-bound lipids over fermentation and baking, the higher physic-chemical and sensory profiles, and the slower starch hydrolysis, firming and retrogradation kinetics of composite breads were obtained.

Influence of the microbial starter and the breadmaking step on the free amino acid profiles of wheat sours, doughs, and breads by reversed-phase high-performance liquid chromatography

Abstract Reversed-Phase High Performance Liquid Chromatography profiles of twenty-two free amino acids from sour doughs (240 dough yield, 35 °C, 20 h, 1.1% ash content), bread doughs (17.5% sour dough addition, 0.5–0.6% ash content) and breads respectively inoculated with Lactobacillus brevis, 25a (with and without yeast) and Lactobacillus plantarum, L-73 and B-39 (without yeast) are investigated. Interactive influence of both the microbial composition of the starter and the breadmaking steps are observed on the individual amino acid pattern. After proofing, a significant decline is noticed in dicarboxylic acids and amides, Ser, and hydrophobic amino acids as well as in total amino acid content in all samples. The extent in the amino acid assimilation by lactobacilli and mainly by yeast is closely concerned with the strain of lactobacilli. In general, homofermentative lactobacilli induce bigger decreases. In addition, aromatic amino acids noticeably deplete during fermentation of both unsoured doughs and ...

Chemical changes in nitrogenous compounds during fermentation of sour doughs and bread doughs

ZusammenfassungEs wird die Entwicklung von Sauerteigen mit Weizenkleiextrakt als Starter und ihren entsprechenden Brotteigen durch Bestimmung der chemischen Veranderungen der in 0,85 mol/L NaCl1 slichen Stickstoffverbindungen wahrend der Gärung untersucht. Die quantitativen Veränderungen des Gesamt-Stickstoffgehalts (TN), des primären Aminostickstoffs (AN) und des α-Aminostickstoffs der freien Aminosauren (AAN) in der loslichen Fraktion (SN) und in den Proteinen (PSN) und Nicht-Proteinen (NPNS) der Subfraktionen. Wahrend der Gärung steigt der Anteil desα-Aminostickstoffs in den freien Aminosäuren (AANSN) und Peptiden (ANNPSN-AANSN) in den Sauerteigen (SD) an und vermindert sich in den Brotteigen (BD). Die Veränderungen sind hoher und schneller beim Peptidstickstoff und größer wahrend der dritten und funften Stufe sowohl beim Sauer- als auch beim Brotteig; in beiden nimmt der Proteingehalt (TNPSN) ab. Die Ergebnisse werden bezogen auf die Qualität der hergestellten Brote besprochen.SummaryThe evolution of sour doughs (SD), prepared using a wheat bran extract as the starting material, and their respective bread doughs (BD) has been investigated by determining the chemical changes which take place in 0.85 mol/L NaCl-soluble nitrogen compounds during fermentation. The quantitative changes determined are: total nitrogen content (TN), primary amine nitrogen (AN) andα-amine nitrogen of free amino acids (AAN) in the total soluble fraction (SN), protein (PSN) and non-protein (NPSN) subfractions. During fermentation,α-amine nitrogen of the free amino acids (AANSN) and peptides (ANNPSN-AANSN), increase in SD and decrease in BD. Changes are larger and faster in peptide nitrogen and even larger during the third and fifth steps. The total protein content (TNPSN) decreases in both SD and BD. Results are discussed in relation to the quality of the bread obtained in each case.

Techno-functional and nutritional performance of commercial breads available in Europe

In recent years, the growing interest for well-being and healthy lifestyle together with an increasing awareness of the close relationship between food and health have boosted the production of an increasing number of novel goods to be placed in both gluten-containing and gluten-free products market. The objective of this study was to provide a realistic and detailed overview of the current bread-market supply in order to evaluate the overall quality of the available offer in this prioritized food industry area. Twenty commercial breads consisting of gluten (n = 10) and gluten-free (n = 10) samples currently available in the European market have been assessed by physical-chemical, technological, nutritional, and sensory determinations. The quality parameters obtained were related to each other by using Pearson correlations, while sample classification was achieved by applying factor analysis. Higher values for protein and bio-accessible polyphenols content, aroma and taste quality, and low and moderate expected glycaemic index corresponded to gluten containing breads. Although the main distinction was between gluten and gluten-free samples as it was expected, classification of breads allowed differentiating samples with different formulations in terms of presence/absence of alternative, innovative, and nutrient-dense raw materials.

Biochemical evolution of nitrogen compounds during fermentation of wheat bread doughs containing pure cultures of lactic acid bacteria

ZusammenfassungEs wurde die Stoffwechselaktivität von 3 Milchsäurebakterien,L. brems, L. plantarum undSt. faecium, während der Gärung von Weizenteigen durch Bestimmung der biochemischen Veränderungen in 0,85 mol/L NaCl-löslichen Stickstoffverbindungen von nicht fermentierten, 4 h und 24 h fermentierten direkt geführten Teigen untersucht. Der Gehalt an Nicht-Protein-Stickstoffverbindungen stieg in allen Teigen während der 24-h-Gärung an. Es wurde exoproteolytische Aktivität festgestellt, besonders in den mitL. plantarum fermentierten Teigen, durch einen erheblichen Anstieg der freien Aminosäuren. Teige, dieL. brevis enthielten, wiesen die größere Peptonbildung bei der 24-h-Gärung auf; es wurden stärkere Nahrungsansprüche an Peptiden mit niedrigem Molekulargewicht beiSt. faecium in kurzen Gärungszeiten beobachtet. Progressiver Abfall des Polypeptid-und Proteingehaltes sowie Abnahme der Protein-Kettenlänge während der Gärung bei den Teigen, dieL. plantarum undSt. faecium enthielten, weisen auf endoproteolytische Aktivität auf lösliche Verbindungen mit hohem Molekulargewicht hin. Eine Zunahme der Größe der Proteinfragmente bei den 4-h-fermentierten Teigen mitL. brevis zeigt eine enzymatische Hydrolyse der nicht löslichen Proteinkette an.SummaryThe metabolic activities of three species of lactic acid bacteria (Lactobacillus brevis, L. plantarum andStreptococcus faecium) during wheat bread dough fermentation have been investigated by evaluating the biochemical changes which occur in 0.85 mol/L NaCl-soluble nitrogen components in unfermented, 4-h and 24-h fermented straight doughs. Non-protein nitrogen compounds increase during a 24-h-fermentation period in all doughs. Exoproteolytic activity is denoted mainly inL. plantarum fermented doughs by an important rise in the free amino acids. Doughs containingL. brevis show a larger production of peptides over a 24-h fermentation period and strong nutritional requirements on low-molecular-weight peptides are evidenced byStreptococcus faecium over short fermentation periods. Progressive depletion in the polypeptides and protein contents as well as a decrease in the estimated protein chain length over the fermentation period forL. plantarum andSt. faecium containing doughs are evidence of endoproteolytic activities in the high-molecular-weight soluble components. An increase in the size of the protein fragments released in the 4-h fermented doughs containingL. brevis denotes enzymatic hydrolysis on non-soluble protein chains.