Åse Hansen

Flavour of sourdough wheat bread crumb

This study investigates the effect of adding sourdough to wheat bread dough on the production of flavour compounds in wheat bread crumb. The sourdoughs were fermented with starter cultures of lactic acid bacteria alone and in combination with sourdough yeasts. The volatile compounds in the bread crumb were isolated by a dynamic headspace technique and extraction analysis, analysed by gas chromatography (GC), and identified on the basis of GC retention times for reference compounds and mass spectrometry (MS). The chemical analyses were combined with sensory evaluation. The volume of the loaves increased significantly when the doughs had 5–20% sourdough added compared with the control bread (bread without sourdough). In the sourdough bread, the content of acetic acid, 2-methylpropanoic acid, and 3-methylbutanoic acid was generally higher, and loaves made with the addition of sourdoughs fermented withLactobacillus plantarum, L. delbrueckii, orL. sanfrancisco had a higher content of 2- or 3-methyl-1-butanol than control bread. Interactions were seen between the starter cultures and the sourdough yeasts, and the production of the following compounds was increased depending on the starter culture used and on the sourdough yeast: ethanol, 2-methylpropanol, 2/3-methyl-1-butanol, 2-phenylethanol, benzyl alcohol, acetic acid, 2-methylpropanoic acid, and 3-methylpropanoic acid. Bread made with an addition of 5% to 15% sourdough fermented withL. sanfrancisco had a pleasant, mild and sour odour and taste.L. plantarum bread had a strong, sour and unpleasant odour and a metallic sour taste with a sour aftertaste, but when the sourdough was also supplemented with the sourdough yeastSaccharomyces cerevisiae, the bread attained a more aromatic wheat bread flavour, which may be caused, in part, by a higher content of 2/3-methyl-1-butanol, 2-methylpropanoic acid, 3-methylbutanoic acid and 2-phenylethanol.

Volatile compounds in wheat sourdoughs produced by lactic acid bacteria and sourdough yeasts

ZusammenfassungDer Gehalt flüchtiger Aromastoffe in Weizensauerteigen, mit 4 verschiedenen Starterkulturen desLactobacillus fermentiert, wurde mit dem Gehalt an flüchtigen Aromastoffen in chemisch gesäuerten Teigen verglichen. Sauerteige sowie chemisch gesäuerte Teige wurden außerdem mit Zugabe von 4 verschiedenen Sauerteighefen hergestellt, um den Einfluß einer Hefezugabe auf die Bildung von flüchtigen Aromastoffen zu untersuchen. Die flüchtigen Aromastoffe der Teige wurden durch eine dynamische Headspace-Technik isoliert, gaschromatographisch analysiert, und auf Grund von Retentionszeiten, Referenzstoffen und Massenspektrometrie identifiziert. Wenige flüchtige Aromastoffe wurden von den chemisch gesäuerten Teigen isoliert im Vergleich zu den Sauerteigen. Der Gehalt an flüchtigen Aromastoffen änderte sich mit der verwendeten Starterkultur. Der höchste Gehalt an Ethanol und Ethylacetat bildete sich in Sauerteigen mit heterofermentativen Kulturen, insbesondere bei der Kultur mitL. sanfrancisco. Neben Ethanol warn-Hexanol der dominierende Alkohol in sämtlichen Sauerteigen. Der Gehalt anderer Aromastoffe war gering. Bei den mit Sauerteighefen angesetzten Sauerteigen erhöhte sich die Anzahl und der Gehalt an Aromastoffen. Ein Höchstgehalt an Ethanol, 2-Methyl-1-Propanol und 2/3-Methyl-1-Butanol erwiesen sich in Sauerteigen mitS. cerevisiae, während der höchste Gehalt an Ethylacetat sich in mit dem Stamm A angesetzten Sauerteigen befand. Der Gehalt an Ester, außer Ethylacetat, war gering. Die Carbonyle Acetoin und Diacetyl bildeten sich in kleinen Mengen in Sauerteigen unter Zugabe von Stamm A.AbstractThe content of volatile compounds in wheat sourdoughs fermented with four different starter cultures of the genusLactobacillus was compared with those in chemically acidified doughs. Sourdoughs as well as chemically acidified doughs were also combined with four different sourdough yeasts to investigate the effect of adding yeasts on the production of volatiles. The volatile compounds in the doughs were isolated by a dynamic headspace technique, analysed by gas chromatography (GC), and identified on the basis of GC retention times for reference compounds and mass spectrometry. Few volatile compounds were identified in the chemically acidified doughs compared to the sourdoughs. The content of volatile compounds in the sourdoughs varied with the starter culture used. Ethanol and ethyl acetate were produced in the highest amounts in sourdoughs fermented with heterofermentative cultures, especiallyL. sanfrancisco. Apart from ethanol,n-hexanol was the dominating alcohol in all the sourdoughs. The content of other compounds was low. When sourdough yeasts were added to the sourdoughs, the number and amount of volatile compounds increased. The content of ethanol, 2-methyl-propanol and 2/3-methyl-1-butanol was highest in the sourdoughs with addedSaccharomyces cerevisiae, whereas the ethyl acetate content was highest in the sourdoughs with added strain A. The content of esters other than ethyl acetate was low. The carbonyls acetoin and diacetyl were produced in small amounts in the sourdoughs with the addition of strain A.

Rapid High-Performance Liquid Chromatography Determination of Tocopherols and Tocotrienols in Cereals

ABSTRACT A rapid normal-phase high-performance liquid chromatography (NP-HPLC) method has been developed for rapid determination of the total content of tocopherols (T) and tocotrienols (T3) in cereals. The new method uses a one-step extraction followed by NP-HPLC coupled with a fluorescence detector. The new method provides a baseline separation of the critical peaks of beta-tocotrienol (β-T3) and gamma-tocopherol (γ-T) within a short time of analysis. The extraction step requires no saponification step or addition of antioxidant. Addition of butylated hydroxytoluene (BHT) had no effect on the stability of vitamin E during sampling. The recovery was 96–100%. The method is demonstrated by successful quantification of vitamin E in barley, wheat, and spelt grains, as well as wheat germ and flours from wheat, spelt, and rye.

Lactic acid bacteria isolated from rye sourdoughs produce bacteriocin-like inhibitory substances active against Bacillus subtilis and fungi

Aim:  To screen five strains of lactic acid bacteria (LAB) isolated from rye sourdoughs for the potential production of antimicrobial substances.

REVIEW: Aroma of Wheat Bread Crumb

ABSTRACT Bread aroma is an important parameter for bread quality, and this review aims to provide an overview of aroma compounds identified in bread crumb and how these compounds are formed. More than 150 volatile compounds were identified in bread crumb, and they mainly originated from the fermentative activity of yeast, from oxidation of flour lipids, and to a lower extent from Maillard reactions. Of those volatile compounds, 45 compounds can be characterized as aroma compounds, because they most likely can be sensed when the bread is eaten because of their high odor activity values and flavor dilution factors. The influence of ingredients and mixing conditions on bread aroma has scarcely been investigated. The fermentation conditions (yeast level and strain as well as fermentation temperature and time) were found to significantly influence the aroma of bread crumb. Yeast level and strain mainly influence formation of compounds directly related to the fermentative activity of yeast, whereas fermentation...

Can architectural design alter the physiological reaction to psychosocial stress? A virtual TSST experiment

Is has long been established, that views to natural scenes can a have a dampening effect on physiological stress responses. However, as people in Europe, Canada and North America today spent 50-85% of their time indoors, attention might also be paid to how the artificial man-made indoor environment influences these mechanisms. The question that this study attempts to start addressing is therefore whether certain design, characteristics of indoor spaces can make a difference to the physiological stress response as well. Using a virtual version of the Trier Social Stress Test, in which the space is computer generated and properties of the space therefore can be systematically varied, we measured saliva cortisol and heart rate variability in participants in a closed room versus a room with openings. As shown by a significant linear contrast interaction between groups and TSST conditions, participants in the closed room responded with more pronounced cortisol reactivity to stress induction, and continued to show higher levels throughout recovery, compared to participants in the open room. No differences were found regarding any part of the autonomic nervous system.

Tocopherol and tocotrienol content in commercial wheat mill streams.

ABSTRACT The content of tocopherols and tocotrienols, collectively known as vitamin E (tocols), was determined in fractions of roller-milled wheat grains. The results showed that vitamin E components are present in all major flour fractions of wheat, but that the vitamin E content and composition differed significantly between fractions. The total content of vitamin E, calculated as alpha-tocopherol equivalents, changed from 16.1 mg α-TE/g in wheat grain to 12.2 mg α-TE/g in roller-milled wheat flour. The germ fraction had the highest content of tocopherols, and the content of α-tocopherol (195.2 μg/g) was 16 times higher (on average) than in any other fraction. The content of tocotrienols was distributed more uniform in the wheat grain with the highest content in the bran fractions, and the content of β-tocotrienol was higher than the content of α-tocopherol in all milling fractions except the wheat germ. The content of β-tocotrienol was 24.1 μg/g in wheat grain, 25.3–31.0 μg/g in the bran fractions, and...

Stability of Vitamin E in Wheat Flour and Whole Wheat Flour During Storage

ABSTRACT The stability of vitamin E during 297 days of storage of wheat flour and whole wheat flour ground on a stone mill or a roller mill, respectively, were studied. One day after milling, the total content of vitamin E, expressed in vitamin E equivalents (α-TE), was 18.7 α-TE and 10.8 α-TE for stone-milled and roller-milled wheat flour, respectively. The difference in total vitamin E content was primarily due to the absence of the germ and bran fractions in the roller-milled flour. The total loss of vitamin E during storage was 24% for stone-milled wheat flour but 50% for roller-milled wheat flour. These results indicate that vitamin E, which is present in high amounts in wheat germ, functions as an antioxidant in the stone-milled wheat flour. Hexanal formation showed that lipid oxidation in roller-milled flour occurred just after milling, whereas the formation of hexanal in the germ fraction displayed a lack period of 22 days, confirming that vitamin E functions as an effective antioxidant in the whe...

Phytase-active yeasts from grain-based food and beer

Aims:  To screen yeast strains isolated from grain‐based food and beer for phytase activity to identify high phytase‐active strains.

Variation of volatile compounds among wheat varieties and landraces

Analysis of volatile compounds was performed on 81 wheat varieties and landraces, grown under controlled greenhouse conditions, in order to investigate the possibility of differentiating wheat varieties according to their volatile compound profiles. Volatile compounds from wheat samples were extracted by dynamic headspace extraction and analysed by gas chromatography-mass spectrometry. Seventy-two volatile compounds were identified in the wheat samples. Multivariate analysis of the data showed a large diversity in volatile profiles between samples. Differences occurred between samples from Austria compared to British, French and Danish varieties. Landraces were distinguishable from modern varieties and they were characterised by higher averaged peak areas for esters, alcohols, and some furans. Modern varieties were characterised by higher averaged peak areas for terpenes, pyrazines and straight-chained aldehydes. Differences in volatile profiles are demonstrated between wheat samples for the first time, based on variety. These results are significant to plant breeders and commercial users of wheat.