Bread Crust Research Articles

Isoflavone profile and biological activity of soy bread.

The present study examines the ability of isoflavone extracts from whole soy bread and two soy bread fractions, crumb and crust, to modulate the proliferation of human prostate cancer PC-3 cells. Total isoflavone content in the two fractions of soy bread were similar (3.17 micromol/g dry basis). However, their conjugate patterns were altered. Both fractions of soy bread contained a similar level of isoflavone aglycones ( approximately 24%). Low concentrations of soy bread extracts increased PC-3 cell proliferation as much as 47% compared to untreated control. This proliferative effect in cell growth was reduced at higher extract concentration. Soy bread crust extract (10 mg/mL) reduced PC-3 cell proliferation by 15% compared to untreated control. Interestingly, wheat bread extracts increased cell proliferation at all concentrations tested. Although extracts from both breads possessed biological activity, only soy bread crust extract reduced PC-3 cell proliferation. This observation may be related to the presence of soy in this bread.

State diagrams to help describe wheat bread processing

SummaryPhysical changes in wheat bread processing can be described by the use of state diagrams and phase transition. State diagrams were constructed from real experimental results that described the glass transition and melting curves for starch and proteins as a function of water content. Wheat gluten protein is the main component responsible for bread dough structural formation, while starch is mainly involved in final textural properties and stability. During processing, hydration of wheat flour induces the glass transition of wheat gluten proteins. The input of mechanical energy during the mixing allows the development of continuous viscoelastic dough due to interactions between rubbery proteins. During baking, irreversible modifications of starch and proteins at high temperatures (>200 °C) and superficial dehydration are responsible for bread crust formation. In the central part of the mixture, starch gelatinization and protein coagulation induce breadcrumb formation. After cooling, the low water content of the crust (3–7%) is sufficient for the transition of bread components from the rubbery to the glassy state. Consequently, structural hardening occurs and is responsible for crust crispness. The higher final water content of the crumb (35–40%) is responsible for rubbery behaviour, which gives structural mobility, smooth breadcrumb behaviour and explains the sensitiveness to starch retrogradation during storage.

Glyphosate applied preharvest induces shikimic acid accumulation in hard red spring wheat (Triticum aestivum).

Glyphosate is a nonselective herbicide used as a harvest aid in a variety of crops. Glyphosate is absorbed into the foliage and translocated to metabolically active regions in the plant where it interferes with the shikimic acid pathway. Experiments were conducted to determine the accumulation and distribution of shikimic acid in wheat treated with glyphosate at soft and hard dough stages of kernel development and to determine the fate of shikimic acid during milling and bread making. Elevated levels of shikimic acid were detected throughout the wheat plant. Shikimic acid concentrations peaked 3-7 days after treatment and then declined until harvest. Shikimic acid content was 3-fold greater in flour and 2-fold greater in the bread derived from treated wheat than nontreated wheat. Similarly, elevated levels of shikimic acid were found in the crumbs and crust of bread made with flour from glyphosate treated wheat. Glyphosate applied preharvest resulted in shikimic acid accumulation in hard red spring wheat and subsequent end-use products.

Effects of a diet rich in advanced glycation end products in the rat remnant kidney model

Background: Food-derived advanced glycation end product (AGE)-analogues, the Maillard reaction products (MRPs), are formed during heat processing. Mainly low molecular weight MRPs are absorbed partially into the circulation and subsequently excreted in urine. In the presence of renal insufficiency, their removal is impaired, with a prolonged increase in plasma levels. Although bioactivity of orally absorbed MRPs has been shown in both experimental and human studies, its relevance in renal insufficiency still is unclear. Methods: In the rat remnant-kidney model (five-sixth nephrectomy [5/6NX]), effects of an AGE-rich and an AGE-poor diet were investigated during a period of 6 weeks and compared with effects in sham-operated healthy (control [CTRL]) rats on renal function (serum creatinine level and proteinuria). In the AGE-rich diet, 25% wt/wt of cornstarch was replaced by bread crusts. Results: Despite pair feeding, the AGE-rich diet resulted in a significant increase in body weight, including weight of the kidney, liver, and heart, in both the CTRL and experimental groups. The AGE-rich diet also enhanced proteinuria in CTRL rats by a factor of 2 and in 5/6NX rats by a factor of 8. Renal function (serum creatinine level and creatinine clearance) in healthy CTRLs did not change significantly. In the 5/6NX group, glomerular filtration rate (GFR) tended to even higher levels. Conclusion: Administration of an AGE-rich diet for 6 weeks does not impair GFR, but induces an increase in proteinuria, in particular, in the 5/6NX rats, indicating detrimental effects on the kidney. Am J Kidney Dis 41(S1):S48-S51. © 2003 by the National Kidney Foundation, Inc.

RAGE-mediated MAPK activation by food-derived AGE and non-AGE products

Investigating the cellular effects of food compounds formed by heat treatment during processing, we recently demonstrated the expression of the receptor for advanced glycation endproducts (RAGE) and the p44/42 MAP kinase activation by casein– N ε -(carboxymethyl)lysine (casein–CML), a food-derived AGE, in the intestinal cell line Caco-2. In this work, we report a Caco-2 p44/42 MAP kinase activation by bread crust and coffee extract. After identification, quantification, and synthesis of two key compounds formed in association with the process-induced heat impact applied to bread dough and coffee beans, those compounds, namely the AGE pronyl-glycine and the non-AGE N-methylpyridinium, were also demonstrated for the first time to activate the p44/42 MAP kinase through binding to RAGE in Caco-2 cells. Blocking of RAGE by an antagonistic antibody and expression of C-terminally truncated RAGE resulted in a reduced Caco-2- and HEK-293-MAP kinase activation. These findings unequivocally point to a RAGE-mediated activating effect of chemically defined food-derived, thermally generated products, both, AGEs and non-AGEs, on cellular signal transduction pathways involved in inflammatory response and cellular proliferation.

Effects of dietary Nε-carboxymethyllysine on expression of the biotransformation enzyme, glutathione-S-transferase, in the rat

Nε-carboxymethyllysine (CML) is an advanced-glycation endproduct found in both heat-treated foods and in living organisms. In the experiments described below, we have evaluated the effects of CML on the expression of the detoxification enzyme, glutathione-S-transferase, in the rat and in intestinal cells in cell culture. In the first animal experiment, casein-linked CML was administered to Wistar rats at two pharmacological doses (110 and 300 mg CML/kg body weight/day) for 10 days. Phase II glutathione-S-transferase (GST) enzyme activity was analysed in the kidneys. In a second study, CML was administered in a diet supplemented with bread crust (25% w/w) such that rats received a moderate dose of 11 mg CML/kg body weight/day. The induction of GST isoenzymes was analysed in the kidneys. In vitro experiments were also performed to study the effects of casein-CML and bread crust on GST induction in the intestinal Caco-2 cell line.Both animal experiments revealed an inductive effect of casein-linked CML and of bread crust on GST activity in the kidneys. The results obtained from the cell culture experiments by enzyme activity analysis and Western blotting confirmed these inductive effects on the GST.In conclusion, dietary-advanced glycation products containing CML were shown to enhance the expression of GST in both animal models and in cell culture.

Structural and functional characterization of pronyl-lysine, a novel protein modification in bread crust melanoidins showing in vitro antioxidative and phase I/II enzyme modulating activity.

Application of an in vitro antioxidant assay to solvent fractions isolated from bread crust, bread crumb, and flour, respectively, revealed the highest antioxidative potential for the dark brown, ethanol solubles of the crust, whereas corresponding crumb and flour fractions showed only minor activities. To investigate whether these browning products may also act as antioxidants in biological systems, their modulating activity on detoxification enzymes was investigated as a functional parameter in intestinal Caco-2 cells. The bread crust and, in particular, the intensely brown, ethanolic crust fraction induced a significantly elevated glutathione S-transferase (GST) activity and a decreased phase I NADPH-cytochrome c reductase (CCR) activity compared to crumb-exposed cells. Antioxidant screening of Maillard-type model mixtures, followed by structure determination, revealed the pyrrolinone reductones 1 and 2 as the key antioxidants formed from the hexose-derived acetylformoin and N(alpha)-acetyl-L-lysine methyl ester or glycine methyl ester, chosen as model substances to mimic nonenzymatic browning reactions with the lysine side chain or the N terminus of proteins, respectively. Quantitation of protein-bound pyrrolinone reductonyl-lysine, abbreviated pronyl-lysine, revealed high amounts in the bread crust (62.2 mg/kg), low amounts in the crumb (8.0 mg/kg), and the absence of this compound in untreated flour. Exposing Caco-2 cells for 48 h to either synthetically pronylated albumin or purified pronyl-glycine (3) significantly increased phase II GST activity by 12 or 34%, respectively, thus demonstrating for the first time that "pronylated" proteins as part of bread crust melanoidins act as monofunctional inducers of GST, serving as a functional parameter of an antioxidant, chemopreventive activity in vitro.

Contribution of Sourdough Lactobacilli, Yeast, and Cereal Enzymes to the Generation of Amino Acids in Dough Relevant for Bread Flavor

ABSTRACTThe amino acid release was determined in wheat doughs supplied with salt, acid, dithiothreitol, or starter cultures to evaluate the relevance of the amino acid concentration on bread flavor. Wheat flour proteinases almost linearly released amino acids and the highest activity of wheat flour proteinases was found in acidified and reduced doughs. The effects of starter cultures on amino acid concentrations depended on their composition. Yeasts exhibited a high demand for amino acids, however, the total amino acid concentrations were not markedly affected by lactic acid bacteria. The individual amino acid contents were determined by the pH during fermentation and microbial metabolism. The formation of proline was favored by values higher than pH 5.5, whereas release of phenylalanine, leucine and cysteine mainly occurred at lower pH. Ornithine was found only in doughs fermented with Lactobacillus pontis. To determine effects of the amino acid concentration on bread aroma, fermented doughs were evaluated in baking experiments. An increased intensity of bread flavor was obtained by preferments prepared with lactic acid bacteria. The roasty note of wheat bread crust could be markedly enhanced by L. pontis. This results support the assumption that flavor of wheat bread is enhanced by increasing the concentration of free amino acids and especially ornithine in dough.

La phase explosive précédant l'extrusion des dômes volcaniques : exemple du dôme rhyodacitique de Dikkartin Dag, Erciyes, Anatolie centrale, Turquie

Abstract The Erciyes stratovolcano, in Central Anatolia, exhibits rhyodacitic domes on its flanks that emplaced after important eruptive pyroclastic events. The changes in eruption dynamics are well defined. Measurements of density and porosity of pumices have been carried out. Initial gas content of erupted magma decreased during the first Plinian phase (units 1 to 3) and then the gas content progressively increased in U4 and in pumiceous ash flow. The latter two deposits contain bread crust bombs that become very abundant in following phreatomagmatic products. The Last Plinian phase, rich in vitreous fragments, where porosity is minimum while density is maximal, preceded the dome extrusion. Although mineralogical and chemical compositions, further thermodynamical conditions of erupted magmas did not change during the eruptive sequence, the eruption mode changed. These changes in eruption mode are the results of the degassing of magma and the meteoric water contribution to the eruption. The transition observed is as follows: Plinian, pyroclastic flow, phreatomagmatism, Plinian and extrusion. To cite this article: E. Sen et al., C. R. Geoscience 334 (2002) 27–33

The Last Lullaby: Poetry from the Holocaust (review)

Book Reviews 159 that the abyss between experience in Auschwitz ,and its recollection afterwards is bridgeable, no matter how empathic the teller of a tale might be. We, who were not there, are inevitably limited as we desire and search for the right words. This applies to Germans and to the world. At best we can demonstrate the willingness to listen to that struggle in the voices ofsurvivors and their children and grandchildren and also to the generations following those who perpetrated the Holocaust or who stood by in silence. Hamida Bosmajian Department of English Seattle University The Last Lullaby: Poetry from the Holocaust, edited and translated by Aaron Kramer, drawings by Saul Lishinsky. Syracuse: Syracuse University Press, 1998. 256 pp. $19.95 (p). Regardless ofwhatever one may think ofthe Holocaust as a suitable course ofstudy or area of research, the fact is that in the last two or three decades the Holocaust has garnered immense interest and will no doubt continue to attract students and scholars for a good while to come. It is hardly surprising, then, that a collection of poetry devoted entirely to poems written during or about the Holocaust should recently be published, translated, and edited by a fme Jewish American poet, Aaron Kramer, and supported by a grant from the Dora Teitelboim Foundation. The book is also abundantly and graphically illustrated by Saul Lishinsky, who besides being a noted artist is also an art therapist. Not that the poems in this collection are in any way therapy. After reading through them, one may instead feel the need for therapy! Many are disturbing in the curious way that many lullabies are disturbing and, closely analyzed, hardly seem able to engender sweet dreams. Here, for example, are a few stanzas from Am Kurtz's "Song of a Substitute Mother": Life's gone to ruin and rack~ not one crumb in the sack. Hush, my child, my curse~ such is our universe. Typhus grips your mother; they've shipped your dad away. In wicked times another must rock you night and day. For a Sudeten child the muddy ground's a bed, your cradle~thoms gone wild, your joy~a crust of bread. 160 Your father's splitting stones in Hitler's swampy land: a helpless pack ofbonesdeaf and dumb and blind. SHOFAR Winter 2001 Vol. 19, No.2 Like other lullabies, the verse form only partially disguises the horrific content of the lines. Ifthe lullaby was sung, the tune might further camouflage the content, grim as it is. Many of the other poems in the collection reflect this paradox of the lullaby; some are rather more comforting, others less. Kramer has done an excellentjob in collecting poems from a wide variety ofpoets who lived through the Holocaust or, dying in it, left behind their work, which miraculously survived. Some, like Avrom Sutzkever, are well known; others, like Chanan Kiel, are less well known. Some poems are by poets who luckily did not experience the Holocaust at first hand, but remain nonetheless haunted by images of it that have become our common heritage. Almost all of the poets come from eastern Europe, especially Poland and the former Soviet Union, where the Holocaust was most terrifying. Kramer, himself an American-born Jew, has written Holocaust poems, though he modestly does not include any in this anthology. Nor does Kramer include the original Yiddish. This is not a bilingual collection, like the Penguin Book of Modern Yiddish Verse or the earlier Treasury of Yiddish Poetry, in both of which Irving Howe had a hand. It is not possible, therefore, to comment on the translations except by hunting down the originals, if they exist, in either of those anthologies or elsewhere. But as every poet understands, translation is always approximate. The best one can hope for is what Robert Lowell called an "imitation," that is, the equivalent in another language of the idiom and emotions the original evokes. In a sense, the translation is a new poem, derivative though it may be, and must be judged on its merits as such. Most of the poems in The Last Lullaby are not great poetry. I doubt that an anthology ofoutstanding poetry in...

The Lunch Box

FICTION The Lunch Box Chris Wood BEFORE THE FINAL BELL RANG, EVERY STUDENT at George Rogers Clark Elementary in Belmont, Virginia, knew about the fight after school. Everyone except Dora Lund. The fight was between a couple of third-graders. Their names were Helen Shifflett and Dora Lund. The idea had been Helen's. As the biggest kid in her grade, she felt compelled to prove her physical prowess over her classmates by beating up on them. Dora Lund was the last one left. Truth to be told, though, Dora was unaware that Helen had saved her for last. Without admitting it to anyone, Helen had done this on purpose. There was something sad about Dora, the pudgy, pigtailed girl who always wore a dress to school. Dora was the middle child of three daughters. Although she had a cute chubby face with apple cheeks and dimples when she smiled, she was also heavy for her age, and that was how people saw her, including her parents. Dora was a quiet, obedient child. She always did what her parents told her to do, but her efforts always seemed to fall just short of their expectations. She was too softhearted. That was her problem. And like all softhearted people, she was gullible. He big sister, Nancy, was prettier like their mother, and little Anne was the son their father never had. The family ate their dinner in quiet, breaking the silence on occasion to ask for something to be passed. They ate formally. The girls remained in their school dresses, and Mr. Lund dined in the suit he'd worn at the men's clothing store that day. Mrs. Lund was always dressed up for some occasion, usually her own. She was a tall, elegant woman who kept her hair colored and permed and had her nails done once a month. She detested any show of bad manners at the table. One must push one's peas onto a fork with a butter knife, she said, or else a crust of bread, but never with the forefinger. That was what people with bad breeding did. Mr. Lund was a stooped, balding man with thick black-rimmed glasses. A devout Methodist, he enjoyed singing from a hymnal after dinner to his wife's accompaniment at the piano. He did all the cooking and cleaning at home and also knew how to sew. 55 During dinner one evening, and for no apparent reason Dora could think of, Mrs. Lund announced that Nancy had always been her favorite daughter. From his end of the table, Mr. Lund claimed Anne for himself. The two sisters looked at Dora for a response. But Dora continued to shovel peas into her mouth without tasting them, as though she hadn't heard anything out of the ordinary. Whenever her parents overlooked her, she just went into a little room inside her head and closed the door to them. After dinner that night, Dora dreamt she went to heaven. The only way to get there was to climb these steep steps that resembled the ones at school, only these steps stretched into the clouds. Dora had to pull herself up with the aid of a railing. There was nothing but sky on either side of her, so she didn't look down. A cold, damp wind howled down on her from the top of the stairs. They were wooden and uncarpeted, for they had been worn smooth by the feet of the dead. Each time Dora took a step the board beneath her foot creaked. The air smelled sweet and thick, like the attic where she liked to play. She kept walking up the stairs until she reached the gate of St. Peter's. Peter was a tall slender man with white, wispy hair and sun-dried tomato skin. He wore a long white robe that was frayed at the cuffs and had been patched in many places. His arms were folded, and he gave off a radiance like Mr. Clean. Clearly this was a mistake, Peter said, checking his long list. No one had called Dora's name. That wasn't supposed to happen for a long, long...

DETERMINATION OF THE SENSORY ATTRIBUTES OF WHEAT SOURDOUGH BREAD 1

ABSTRACTA lexicon for describing the flavor of wheat sourdough bread (WSB) was developed. A highly trained, descriptive sensory panel identified, defined, and referenced 32 flavor attributes for WSB. To determine the flavor characteristics of WSB, 37 samples were selected or prepared to represent a wide range of both commercial and laboratory variations. Crust and crumb of sourdough bread had different flavor properties; thus, they were evaluated separately. Twenty six attributes described the characteristics of sourdough bread crumb, and 28 attributes described the characteristics of crust. Some attributes were found in most or all samples, but many attributes were found in only one or a few samples. All 37 samples had distinctly different flavor attributes and intensities in both crumb and crust samples. The principal components analysis for crumb and crust indicated that the number of attributes could not be reduced into a smaller set of components that completely described the wide range of breads used in this study. However, reducing the number of attributes measured might be possible when only a few WSB samples are evaluated.

Is fungal alpha-amylase in bread an allergen?

The enzyme alpha-amylase from Aspergillus oryzae used in bakeries to improve the bread quality has been identified as an inhalative allergen in baker's asthma. It is doubtful whether this enzyme can induce allergic sensitization in regular bread consumers. To find out whether fungal alpha-amylase in bread and rolls retains its antibody-binding capacity and allergenicity after the baking procedure. Rabbit antibodies directed to fungal alpha-amylase were used for the development of a two-site enzyme-linked immunosorbent assay (ELISA). This assay was used to analyse different fractions of bread and rolls baked with the usual amounts of alpha-amylase in comparison with control products without added enzyme. Competitive experiments between bakers' sera containing specific immunoglobulin (Ig) E to alpha-amylase and the rabbit antibodies were performed. Additionally, specific IgE binding to fungal alpha-amylase was inhibited by native or heated alpha-amylase. With the highly specific two-site ELISA for native alpha-amylase in the crust of bread bottom and sides, 2.3-7 ng antigenic alpha-amylase per gram crust were measured. No alpha-amylase could be detected in the crumb fractions. Rabbit antibodies to native alpha-amylase completely inhibited human IgE binding to alpha-amylase allergen disks. The results prove residual antibody-binding capacity of alpha-amylase in bread crusts and in the crust of some rolls. In comparison with the content of alpha-amylase in dough, between 0.1 and 20% of the antibody-binding capacity remained.

Radical-assisted melanoidin formation during thermal processing of foods as well as under physiological conditions.

Color-generating reactions of protein-bound lysine with carbohydrates were studied under thermal as well as under physiological conditions to gain insights into the role of protein/carbohydrate reactions in the formation of food melanoidins as well as nonenzymatic browning products in vivo. EPR spectroscopy of orange-brown melanoidins, which were isolated from heated aqueous solutions of bovine serum albumin and glycolaldehyde, revealed the protein-bound 1,4-bis(5-amino-5-carboxy-1-pentyl)pyrazinium radical cation (CROSSPY) as a previously unknown type of cross-linking amino acid leading to protein dimerization. To verify their formation in foods, wheat bread crust and roasted cocoa as well as coffee beans, showing elevated nonenzymatic browning, were investigated by EPR spectroscopy. An intense radical was detected, which, by comparison with the radical formed upon reaction bovine serum albumin with glycolaldehyde, was identified as the protein-bound CROSSPY. The radical-assisted protein oligomerization as well as the browning of bovine serum albumin in the presence of glycolaldehyde occurred also rapidly under physiological conditions, thereby suggesting CROSSPY formation to be probably involved also in nonenzymatic glycation reactions in vivo.

Recycling of bakery wastes using an amylolytic lactic acid bacterium

Production of lactic acid from discarded bread by using an amylolytic lactic acid bacterium, Lactobacillus amylovorus, was investigated to recycle bakery wastes. Addition of 2.0% yeast extract in the medium containing 3.58% bread crust caused maximum acid production. The stimulation of lactic acid production by less expensive materials such as corn steep liquor, defatted soybean powder, rice bran and wheat bran at additional levels of 2.0% was also observed, but limited. Acid production in the medium supplemented with 2.0% corn steep liquor was enhanced by the further addition of 2.0% defatted soybean powder and reached the levels comparable to medium containing 1.4% yeast extract. In the medium supplemented with 2.0% corn steep liquor and 2.0% defatted soybean powder, 47.2% of total sugars was converted to dl-lactic acid in 72 h under static incubation. When the baking test was carried out, the bread made with the addition of the culture filtrate was significantly ( P < 0.05) preferred over those with and without addition of commercial fermented seasoning with respect to taste and overall acceptability.

冷凍生地製パン法に関する研究 （第１報） パン表皮の荒れに及ぼす冷凍前の生地膨張率の影響

冷凍生地製パン法に関する研究 （第１報） パン表皮の荒れに及ぼす冷凍前の生地膨張率の影響

Modelling of browning kinetics of bread crust during baking

A mathematical model was set up to predict browning kinetics of bread crust during baking. A bread dough was placed into a cylindrical steel mould and baked in a pilot forced-convection oven at 200 and 250°C. The sample surface temperature was measured using both a type J thermocouple and an infrared thermometer. Surface browning (ΔE) of bread crust during baking was measured by a tristimulus colorimeter. The kinetic model for bread crust browning was obtained by instant heating of dried crumb on contact with a refractory plate at 140, 150, 165, 185, 210, 235 and 250°C. At all temperatures Δ E tended asymptotically to ΔE ∞ = 52, which corresponded to the burnt sample. The colour difference varies as a function of first-order kinetics. The rate constant k depends on temperature according to the Arrhenius equation ( k o = 42,000 s −1; E a = 64,151 J/mol). Kinetics was validated under dynamic temperature conditions: the experimental results were compared with those obtained from a mathematical model for heat and mass transfer during baking connected to the kinetic model for browning.

Determination of the thermal diffusivity of bread as a function of porosity

Experiments were carried out to determine the thermal diffusivity and the apparent density of bread crust and crumb as a function of porosity. The thermal diffusivity was determined by comparing the temperature profile obtained experimentally during heating of bread at 100 °C in an oven and the temperature profile calculated using a computer program to simulate heat transfer inside the product. Experimental measurements showed that the apparent density ϱ (kg/m 3) of the crumb and the crust follows a linear trend as a function of porosity ε(%): For the crumb: ϱ = 979 − 9.90 ε For the crust: ϱ = 895 − 9.0 ε The thermal diffusivity α ( m 2 s ) follows an exponential trend as a function of porosity: For the crumb: α = exp (0.01 ε − 15.25) For the crust: α = exp (0.0062 ε − 15.30)

Potent odorants of rye bread crust-differences from the crumb and from wheat bread crust

Aroma extract dilution analyses revealed twenty-eight odorants in fresh rye bread crust and twenty in its crumb. On the basis of high flavour dilution factors, methional (boiled potato), 3-methylbutanal (malty), (E)-2-nonenal (green, tallowy), (E,E)-2,4-decadienal (fatty) and acetic acid (sour, pungent) belonged to the potent odorants of the crust, and phenylacetaldehyde, (E)-2-nonenal and (E,E)-2,4-decadienal to those of the crumb. Compared with the crust, especially the odour activities of methional, 3-methylbutanal, 2-ethyl-3,5-dimethyl-pyrazine and 4-hydroxy-2,5-dimethyl-3(2H)-furanone were significantly lower in the crumb. Calculation of the odour activity values (OAV; ratio of concentration to odour threshold) indicated that the higher OAV of methional in the rye crust and the higher OAV of 2-acetyl-1-pyrroline in the wheat bread crust mainly contributed to the flavour difference of the two kinds of bread.

Improvement and stabilization white of bread flavour

AbstractEffect of adding the model system mixture (D,L‐lysine · HCl, L‐proline and D‐glucose) on the sensory properties and volatile components of fresh bread and bread stored for 3 days were investigated. The results showed that the model system mixture improved the crust colour and flavour of fresh bread and kept the freshness, retarded the staling and improved the quality of the bread samples stored for 3 days. Analysis of the crust aroma of the bread samples showed that 2‐acetyl pyrazine, 2‐acetyl pyridine and 2‐methyl‐3‐ethyl pyrazine, which may be responsible for bread crust aroma, were determined at high concentration in the bread sample containing 0.24% model system mixture. The concentration of pyrazine derivatives increased during storage whereas the carbonyl, pyrrol and furan derivatives decreased.