Chorleywood Bread Process Research Articles

The history of food reformulation

The history of food reformulation

Formation of Dityrosine Cross-Links during Breadmaking

To establish its significance during commercial breadmaking, dityrosine formation was quantified in flours and doughs of six commercial wheat types at various stages of the Chorleywood Bread Process. Dityrosine was formed mainly during mixing and baking, at the levels of nmol/g dry weight. Good breadmaking flours tended to exhibit a higher dityrosine content in the final bread than low quality ones, but no relationship was found for dityrosine as a proportion of flour protein content, indicating that the latter was still a dominant factor in the analysis. There was no correlation between gluten yield of the six wheat types and their typical dityrosine concentrations, suggesting that dityrosine cross-links were not a determinant factor for gluten formation. Ascorbic acid was found to inhibit dityrosine formation during mixing and proving, and it has no significant effect on dityrosine in the final bread. Hydrogen peroxide promoted dityrosine formation, which suggests that a radical mechanism involving endogenous peroxidases might be responsible for dityrosine formation during breadmaking.

Novel genes on chromosome 3A influencing breadmaking quality in wheat, including a new gene for loaf volume, Lvl 1

It is proposed that a single gene, Lvl 1, can explain variation in Chorleywood Bread Process loaf volume, crumb colour and score in bread wheat ( Triticum aestivum L.). The gene is located on the long arm of chromosome 3A about 30–40 cM from the centromere. It is possible that the Lvl 1 gene also determines gel-protein weight, although this could be the effect of a closely associated gene. A quantitative trait locus, which is likely to be a single gene controlling Hagberg Falling Number, was also located close to the centromere. Finally, the location of a gene (or genes) affecting gel-protein G′ (elastic modulus) could not be established but it may be located distally on the long arm, but proximal to the marker Xgwm 480.

Wheat protein quality in relation to baking performance evaluated by the Chorleywood bread process and a hearth bread baking test

Abstract The relationships between wheat protein quality and baking properties of 20 flour samples were studied for two breadmaking processes; a hearth bread test and the Chorleywood Bread Process (CBP). The strain hardening index obtained from dough inflation measurements, the proportion of unextractable polymeric protein, and mixing properties were among the variables found to be good indicators of protein quality and suitable for predicting potential baking quality of wheat flours. By partial least squares regression, flour and dough test variables were able to account for 71–93% of the variation in crumb texture, form ratio and volume of hearth loaves made using optimal mixing and fixed proving times. These protein quality variables were, however, not related to the volume of loaves produced by the CBP using mixing to constant work input and proving to constant height. On the other hand, variation in crumb texture of CBP loaves (54–55%) could be explained by protein quality. The results underline that the choice of baking procedure and loaf characteristics is vital in assessing the protein quality of flours.

The Determination of Wheat Breadmaking Performance and Bread Dough Mixing Time by NIR Spectroscopy for High Speed Mixers

A non-invasive near infrared (NIR) technique has been used to identify changes in the development of bread dough during mixing. A Perten DA-7000 Diode Array NIR instrument with a fibre optic probe attachment was used. Both breadmaking and biscuit making varieties of wheat were examined. Doughs were mixed using a laboratory scale Chorleywood Bread Process (CBP) mixer and NIR spectra were gathered (one every 2 s). Flour quality data were used to determine the relationship between NIR and breadmaking quality attributes and to study varietal differences in breadmaking performance. Instrumental and sensory techniques were used to establish the important quality attributes of commercially and laboratory produced bread. NIR spectra and mixer torque were measured at different mixing times to obtain an overall picture of the mixing process from the initial hydration of the flour particles through optimum dough development until overmixing had occurred. Loaves were produced and assessed for volume by seed displacement and crumb structure using an image analysis technique. The dough elastic modulus was measured at a range of mixing times using a Bohlin VOR Rheometer. Comparison of results from the NIR spectra, dough properties and bread quality was carried out. Results revealed a relationship between the rheological properties of dough and the final quality parameters of bread. NIR was shown to have considerable merit in following dough changes during mixing which were related to final bread quality and thus has the potential to be used as an on-line method for controlling breadmaking mixers.

A Rheological Study of Mechanical Dough Development and Long Fermentation Processes for Cream-Cracker Dough Production

In the manufacture of products such as bread and cream-crackers mechanical development and long fermentation processes are used to develop dough. A rheological study of cream-cracker doughs made using both types of process has shown that fermentation weakens, but does not rearrange, intermolecular interactions. The rearrangement of storage proteins into a continuous network of gluten is achieved by the shearing action of mixing, which need only be gentle after a sufficient period of fermentation, but must be intense if prior fermentation is omitted, as in mechanical dough development. In the long fermentation process a dough with the desired characteristics was produced following a minimum of 4 h fermentation time. Dough with similar rheology was produced by mechanical development when additional water was used in the recipe. For mechanically developed cream-cracker doughs there was also an increase in the elasticity of the developed gluten. When the Chorleywood Bread Process was invented it was found that more water and less protein were required to achieve the same dough rheology as in long fermentation processes. It seems that the same relationship between mechanical dough development and long fermentation may apply to other products, such as cream-crackers. These results confirm that the technological experience gained by switching from long fermentation to mechanical dough development processes for bread production could be applied to other products such as cream-crackers. © 1997 SCI

The Role of Fat in the Stabilisation of Gas Cells in Bread Dough

Abstract Electron microscopy has shown that during dough mixing by the Chorleywood Bread Process, fat crystals develop a crystal–water interface as they emerge from droplets of shortening and that they then adsorb to the gas–liquid interface of bubbles. In this process, the interface surrounding each crystal coalesces with the gas–liquid interface of the bubble. This adsorption process was not observed when triglyceride was added to doughs in the form of oil. The expansion of bubbles during proofing leads to the adsorption of many more fat crystals as they are encountered in the aqueous phase. During baking, fat crystals melt and thereby make it possible for the crystal-liquid interface to be incorporated into the surface of the bubble as it expands. This transfer of interfacial material from crystals to bubble surface explains how the addition of shortening to dough allows bubbles to expand during baking without rupturing, thus producing high volume bread with fine crumb structure. It follows that the amount of interface transferred to bubble surfaces for any given weight of fat is inversely proportional to the size of the crystals in the shortening and that therefore shortenings containing small crystals are more effective in producing high quality bread than those containing large crystals. A mechanism is now proposed which, for the first time, explains the precise role of fat crystals in this process and why the addition of oil is not effective.

The glutenin fraction of wheat protein: The importance of genetic background on its quantity and quality

AbstractThe influence of high‐molecular‐weight glutenin subunits on the properties of the gel‐protein fraction of glutenin proteins in wheat was determined on 20 varieties grown in the 1989 UK Recommended List trials. Both the presence of subunit 1 (chromosome 1A) and the 1B/1R rye translocation were shown to influence gel‐protein weight and breakdown rate during mixing. The gel‐protein tests were correlated with CBP (Chorleywood Bread Process) loaf volume, but they did not add anything to the correlation between Glu‐1 score and loaf volume. Both gel‐protein tests indicated that phenotypic variation could be almost as large as genotypic variation. Breakdown rate was able to detect the abnormal properties of Pastiche (weak) and Fresco (extra‐strong) that were not observed using established quality tests such as the sodium dodecylsulphate sedimentation volume.

The microstructure and gas retention of bread dough

Scanning electron micrographs of bread doughs produced by the Chorleywood Bread Process indicate that towards the end of 50 min proving, discontinuities were apparent in the starch-gluten matrix surrounding gas cells. On the basis of these observations, a revised model of expanded dough structure is proposed in which the integrity of the gas cells is maintained by a liquid film with surface active materials at the gas/liquid interface. The film is initially surrounded and reinforced by the starch-gluten matrix, which fails to enclose the gas cells completely at later stages of expansion, leaving areas between adjacent cells that contain only the film. Early rupture of the gas cells and consequent loss of expansion would be caused by deficiencies in the extensibility of the starch-gluten matrix and/or in the surface activities of the liquid film.

Thiols in flour and baking quality

Baking quality (LV) was defined as loaf volume per gram of loaf protein. Further attempts to find negative correlation between LV and small thiols bound by disulphide bonds (SS) to gluten failed, but this was almost certainly because the method was flawed. A new approach was devised to measure on the same sample: free sulphydryl groups (SH) in glutenin, diffusible thiols in flour, and thiols bound to protein by SS. Both methods showed the existence of bound thiols; corrected values in the old method had a mean of 1·5 μmol per gram of gluten; in the new they ranged from ∼ 0·9 to 2·3 μmol per gram of flour protein with a mean of 1·6. Altogether three ways were tried of measuring diffusible thiols in flour (possibly the rheologically active ones). The most specific reagent measured 14–16% of accessible thiol as diffusible. A second method gave slightly lower values but this could be explained by side reactions. High values, with a third reagent, were almost certainly due to incomplete reaction. Probably for the first time, it was shown that untreated glutenin molecules in flour carry free SH. The use of phenyl mercuric acetate suggested ∼ 1/8 SH a glutenin chain (of average mol. wt 50 000). Higher results with iodoacetamide ranged from 0·17 to 1·1, but these probably included extra SH, from reaction of glutenin with active thiols before they could be blocked, and/or from attack on labile SS in glutenin. The amount of free SH on glutenin was negatively correlated with LV in the Chorleywood Bread Process (CBP), but not significantly in the 3 h long fermentation process (LFP). The results suggest that an active thiol attacks a glutenin SS when flour is wetted to add both SH and bound thiol; it can also form an SS with an SH on glutenin by oxidation. The hypothesis that the mol. wt of glutenin controls about half the variation in baking quality is compatible with recent findings that baking quality depends on the type of high molecular weight subunit in glutenin. Payne found one-third to two-thirds the variation in baking quality was linked with variation of subunit composition, so both the mol.wt of glutenin, and its high mol.wt subunits, affect baking quality. Further studies of the effect of thiols on the mol.wt of glutenin (and therefore on baking quality) could well be done on wheats of constant subunit composition. With a commercial flour the CBP was less tolerant of added thiols than the LFP. Cysteine is only about a tenth as active as the others in the LFP. Its effect (when large amounts were used) did not seem to involve an enzyme since the d- and l-forms were equally active. In a trial with 24 flours, protease activity was uncorrelated with LV. A further measurement was made of SH in three stored flours.

The effect of group 5 chromosomes on the free polar lipids and breadmaking quality of wheat

Free (hexane-extractable) polar lipids (PoL) were determined in flours milled from wheats differing only in their group 5 chromosomes. Ditelosomic lines lacking the short arm of chromosome 5D (DT5DL) were much harder and had less free PoL than normal wheats or the corresponding 5A ditelosomics (DT5AL). Substitution of chromosome 5D of Chinese Spring (CS) by homologous chromosomes from other varieties or by 5U from Aegilops umbellulata, and of chromosome 5A of CS by 5U, gave a series in which increasing hardness was strongly correlated with decreasing free PoL. Analysis of CS x CS(Hope 5D) crosses that were non-recombinant or recombinant for the genes Vrn3/vrn3 (spring/winter habit) and Ha/ha (soft/hard endosperm texture) showed that there was transgressive segregation of two (or, possibly more) genes controlling levels of free PoL. One of these genes could be allelic to Ha, or is closely linked to it. The second gene is probably located on the long-arm proximal to Vrn3. The new genes have been given provisionally the symbols Fpl-1 and Fpl-2. Loaves made by the Chorleywood Bread Process with flour from ditelosomic and substitution lines showed marked decreases in loaf volume with decreasing free PoL. Limited evidence from recombinant lines supported the link between Fpl-1 and Fpl-2 and loaf volume.

The bread improving effect of fungal α-amylase

Nine characteristics of 62 commercial flours have been measured and the volumes recorded of loaves baked from them by the Chorleywood Bread Process (a mechanical dough development procedure) in the absence and presence of three levels of added fungal α-amylase (FAA). A further 22 flours have been used to test the predictive powers of regressions, derived from the original 62, between loaf volume, flour characteristics and total α-amylase activity. The volumes of loaves from all 84 flours increased with increase in the FAA activity added. The loaf volume/FAA response curve had a negative exponential form but had poor predictive ability. The loaf volume improving effect of FAA did not correlate with measured flour characteristics. Fungal α-amylase prolonged dough expansion time during baking. Multiple regression analysis was used to show that loaf volume was correlated positively with flour protein and negatively with flour colour.

Effects of oxidising improvers, an emulsifier, fat and mixer atmosphere on the performance of wholemeal flour in the chorleywood bread process

The effects of oxidants, an emulsifier, fat and mixer atmosphere on loaf quality (volume and texture) of wholemeal bread, made by a mechanical dough development procedure (Chorleywood Bread Process), were investigated. Both ascorbic acid (AA) and the emulsifier, diacetyl tartaric acid esters of monoglycerides (DATEM) gave substantial improvements in loaf volume, and a marked synergistic effect between AA and DATEM was observed in both loaf volume and texture. When AA (75 ppm) was used in the recipe and the doughs mixed under partial vacuum or in an atmosphere of 10 % O2:90 % N2, loaf volume was lower than when mixed in air; dehydroascorbic acid (75 ppm) was more effective than AA at low O2, levels. No improvement in loaf volume was obtained when O2 levels were increased above that in air. Loaves baked, using a low fat (0·7 %, flour weight basis) recipe, from wholemeal flour that had been stored at 20 °C for 17 weeks had lower volumes than those from wholemeal kept at –20°C. Increasing the fat content of the recipe to 2% restored the loaf volumes given by 20 °C-stored wholemeals to those obtained with frozen wholemeal.

Survival of bromate and bromide in bread baked from white flour containing potassium bromate

AbstractThe amounts of potassium bromate surviving in bread made using the Chorleywood Bread Process were less than 006 mg kg−1 (the current limit of detection) when this substance was added to flour at levels up to 75 mg kg−1 on flour weight; even when the addition level reached 100 mg kg−1, only 0.22 mg kg−1 was found in the bread. Within the limits of experimental error all of the added potassium bromate not detected unchanged in the bread was accounted for in the form of bromide.

Thiols in flour and breadmaking quality

A differential pulse polarograph was used to measure accessible thiols in wheat flour suspensions at pH 4·2 with phenyl mercuric acetate as the reagent. Loaf volume per gram of loaf protein (LV) showed some inverse correlation with accessible thiol content of flour in a trial on 53 English wheats from 39 varieties (r = −0·523; P < 0·001). At least four measurements were done on each flour. The mean level of accessible thiol for the 53 flours was 0·85 μmoles g −1. From trials in which bread was baked from doughs with added thiols it was concluded that bread quality began to fall off in the Chorleywood Bread Process when 0·2–0·3 μmol thiol per gram of flour were added. Evidence from elsewhere as well as this paper suggests that not more than about quarter the endogenous thiols are rheologically active. This would explain why better correlation between thiol content and LV was not found. Twenty-three of the 53 results were done on nine varieties, and these showed that accessible thiol varied significantly within a variety. Three more attempts to find significant amounts of thiol in glutenin failed. Excess l- cysteine or glutathione acting on glutenin at dough pH in the absence of denaturing agents reduced ∼90% and ∼35%, respectively, of its disulphide bonds. When five flours were analysed for free cyst(e)ine a mean value of 76 nmol Cys/2 per gram of flour was found (range 59 to 86).

Lipid compositions, baking qualities and other characteristics of wheat varieties grown in the U.K.

The breadmaking performance of flours milled from U.K.-grown wheat varieties has been studied in relation to the composition of the ‘free’ lipids extractable by light petroleum (b.p. 60–80°C) from the wheats and to other attributes of the flours. The results with six varieties grown at three sites in 1983 appeared to confirm reports of significant correlations between loaf volume and ‘free’ polar lipid contents in wheat samples from the U.S.A. and Canada. However, with 15 winter varieties and six spring varieties grown at three sites in 1984, no significant correlations were found between any lipid parameter and loaf volume or quality score of breads prepared by both the Chorleywood Bread Process and long fermentation methods. The best single indicator of breadmaking quality was the sodium dodecyl sulphate (SDS) sedimentation test. No useful equations for predicting breadmaking quality were found by multiple regression techniques using the various flour properties measured in this study.

The effect on baking quality of interaction between milling fractions during the storage of wholemeal flour

The volume of bread baked from wholemeal flour by a mechanical dough development procedure (Chorleywood Bread Process) decreased during storage of the flour at +20 °C for twenty weeks. Storage of three individual milling fractions allowed interactions between the endosperm and non-endosperm fractions to be detected. The germ stored at +20 °C caused no deterioration in baking quality of reconstituted ‘wholemeal’ whereas the bran and white flour fractions gave only small decreases in loaf volume (5% and 3% respectively after 27 weeks) although the fatty acid content of each fraction was very high after storage at +20 °C. Combination of all three +20 °C fractions before baking resulted in a further 5% decrease in loaf volume, indicating an interaction between the stored fractions during breadmaking. A much greater effect on loaf volume (total decrease of 27%) was observed when the streams were blended together before storage, showing that a more significant interaction occurred during storage. A lipid interchange experiment using flours blended before and after storage showed that the extracted lipid fraction could account for a part of the decrease in baking quality but that the unextracted flour residue was also involved.

LITERATURE ABSTRACTS

GENERAL PRINCIPLES: pH Dependence of the Rheological Properties of Hydrogels of Gelatin, Agarose and Konjak Mannan. M. Watase GENERAL PRINCIPLES: Compaction of Bulk Corn Kernel to Failure. P. B. McNulty and N. N. Mohsenin GENERAL PRINCIPLES: A Comparison of the Rheological Properties of Heat‐Iiiduced Protein Gels from Egg Albumen and Bovine Plasma. (Lecture). D. W. Hickson, C. W. Dill, R. N. Morgan, V. E. Sweat and Z. L. Carpenter GENERAL PRINCIPLES: A Cell Model Theory of the Shear Viscosity of a Concentrated Suspension of Interacting Spheres in a Non‐Newtonian Fluid. Hideho Tanaka and James L. White. OBJECTIVE MEASUREMENTS: Apparatus for the Measurement of the Mechanical‐Rheological Properties of Gels. F. Horkay, M. Nagy and M. Zrinyi. OBJECTIVE MEASUREMENTS: Experiments For the Determination of the Specific Resistance of Comminuted and Pressed Apple Against Its Own Juice. 1. Körmendy FACTORS AFFECTING TEXTURE: Kinetic Analysis of Continuous Yoghurt Fermentation. O. Reichart. FACTORS AFFECTING TEXTURE: Composition of Bioassay Data on the Wholesomeness of Irradiated Food Items. J. Barna. FACTORS AFFECTING TEXTURE: A Relation Between Gluten Protein Amide Content and Baking Performance of Wheat Flours. F. MacRitchie. FACTORS AFFECTING TEXTURE: Quality Attributes of Frozen Okra as Influenced by Processing and Storage. O. C. Aworh, A. O. Olorunda and O. Akibo. FACTORS AFFECTING TEXTURE: Storage Stability of Dehydrated Food—Evaluation of Literature Data. R. Villota, I. Saguy and M. Karel. FACTORS AFFECTING TEXTURE: The Composition, Rheological Properties and Breadmaking Behaviour of Stored Flours. B. M. Bell, N. Chamberlain, T. Hylton‐Collins, D. G. H. Daniels and N. Fisher. FACTORS AFFECTING TEXTURE: The Effects of Pure Saturated and Unsaturated Fatty Acids on Breadmaking and on Lipid Binding, Using Chorleyw ood Bread Process Doughs Containing a ‘Model Fat’. B. M. Bell, D. G. H. Daniels and N. Fisher. RELATIONSHIP TO STRUCTURE: Electron Microscopy Study on the Crystallization Racemes in Fat Globules During the Ripening of Cream. W. Buchheim and D. Precht. RELATIONSHIP TO STRUCTURE: Electron Micraecopic Studier on the Physical Structure of Spreadable Fate 1. The Micro‐Structure of Fat Globules in Butter. D. Precht and W. Buchheim. RELATIONSHIP TO STRUCTURE: The Submicroscopic Structure of Heat Coagulated Milk. A. M. Knoop and K. E. Peters. RELATIONSHIP TO STRUCTURE: The Different Development of the Structure in Harzer, Tilsit and Camembert cheese During Ripening. A. M. Knoop and W. Buchheim.

The composition, rheological properties and breadmaking behaviour of stored flours

AbstractFlours milled from English (‘weak’), Canadian (‘strong’) and mixed English and Canadian wheats (‘medium’) had different rates of lipolysis (weak&gt;medium&gt;strong) during prolonged storage at ambient temperatures (average about 12°C). Lipolysis was more rapid in the medium flour at 25°C, but was very slow in ‘control’ flours kept at ‐ 20°C in an inert atmosphere. Loss of baking quality in stored flours was assessed using the Chorleywood Bread Process (CBP), a long fermentation process (LFP) and the Activated Dough Development process (ADD). The loaf volume changes varied with the flour type and test method, especially depending on whether or not fat was included in the recipes. In tests with fat, the CBP was the most sensitive to deteriorative changes (strong≃medium&gt;weak); with the medium and strong flours, loaf volumes were nearly constant for 24 months before decreasing rapidly. Deterioration became apparent more gradually when using LFP and ADD tests with fat. When fat was omitted, short‐term improvement (weak&gt;medium&gt;strong) occurred with all three baking methods, but there was subsequent loss of volume. To account for these changes in baking behaviour, it is suggested that the tests differ in their sensitivity to flour type and variations in dough composition, especially to the level of bakery fat, the level of fatty acids (generally deleterious), and to protein changes which were also detectable by rheological tests on stored flour doughs (flour ‘maturation’; generally beneficial).

The effects of pure saturated and unsaturated fatty acids bon breadmaking and on lipid binding, using chorleywood bread process doughs containing a ‘model fat’

AbstractWhen a fresh flour dough containing a model fat prepared from pure saturated and unsaturated triglycerides was supplemented with pure oleic or linoleic acids in amounts sufficient to raise the level of unesterified fatty acids to that obtained with a flour badly deteriorated by age, the acids were equally detrimental to loaf volume. Margaric acid added at the same level was not deleterious. Lipid binding studies showed that both unsaturated fatty acids behaved similarly during doughmixing, not only becoming largely ‘bound’ themselves, but also causing increased binding of glyceryl trioleate and flour lipids. Conversely, margaric acid remained largely ‘free’ and did not affect the binding of other dough lipid constituents.