IMPROVEMENT OF THE WHEAT AND CORN BRAN BREAD QUALITY BY USING GLUCOSE OXIDASE AND HEXOSE OXIDASE

The effects of addition of wheat (10, 20 and 30%) and corn bran (10 and 20%) on rheological and bread making properties of flour were examined. To improve dough and bread properties, glucose oxidase (GO) and hexose oxidase (HO) (15–30 and 45 mg/kg) were used separately in each bran-wheat flour formula with L-ascorbic acid at 75 mg/kg, glucose at 0.5% and vital gluten at 9.2%. Water absorption and development time increased as the amount of wheat and corn bran increased, while dough stability, maximum resistance to extension, extensibility, energy and loaf volume decreased. Corn bran was found to be more detrimental to dough rheology and bread characteristics than wheat bran. Corn bran and wheat bran could be used at bread making up to levels of 10 and 20%, respectively. Addition of 30 mg/kg of HO in combination with constant additives was most effective in improving dough and bread characteristics and GO with its 15 mg/kg usage level followed it. Further increasing of enzyme levels led to over oxidizing of doughs and breads.

PRACTICAL APPLICATIONS

Corn bran up to 10% and wheat bran up to 20% levels can be used in bread making. To improve dough and bread quality, besides L-ascorbic acid (75 mg/kg) and vital gluten (as a percentage of added bran weight), GO (15 mg/kg) or HO (30 mg/kg) could be incorporated into wheat flour-bran mixtures. However, the amount of enzyme should be carefully chosen because when they are used above the mentioned levels, they cause overoxidation of doughs and small loaf volumes are obtained. As a conclusion; by using the corn bran, which is a by-product of the starch industry, not only could it be possible to offer healthy alternative breads which contain high amounts of dietary fiber to consumers, but it could also be possible to obtain economical value by evaluating such a by-product in the bread industry.     

EFFECT OF PENTOSANASE ON DOUGH AND BREAD PROPERTIES PRODUCED BY DIFFERENT TYPES OF FLOURS

ABSTRACT

The effects of pentosanase at different doses (20, 60 and 100 ppm) on physical dough properties and bread quality were studied using three types of wheat flours. Flour A was a regular bread flour, flour B had a high hardness ratio and protein content, and flour C was prepared from the same blend of flour A but had a high extraction ratio. Regarding farinograph data, water absorption values of the high extraction (86%) flour C and high hardness (65%) blend flour B increased with introduction of pentosanase. Extensibility values of the flours increased moderately with pentosanase addition, while resistance and energy values decreased. The volume of breads made with flours C and B decreased upon addition of pentosanase. But loaf volume of breads prepared with regular bread flour A with 50% hardness and 76% extraction rate increased with high levels of pentosanase addition. In conclusion, flour A as a regular bread flour gave satisfactory results with pentosanase supplementations, whereas the harder‐blend (65%) and higher‐extraction‐rate (85%) flours from the same cultivars did not.

PRACTICAL APPLICATIONS

Pentosanase addition was more effective on soluble pentosans than on insoluble ones. Because of these effects, it enhanced the bread‐making properties of regular flour more effectively than those of the high‐extraction and harder‐blend flours of the same cultivars.

     

Effects of trypsin‐hydrolyzed wheat gluten peptide on wheat flour dough

BACKGROUND: Gluten peptide was prepared by trypsin hydrolysis and characterized by high‐performance liquid chromatographic analysis. The effects on non‐frozen and frozen doughs of trypsin‐hydrolyzed gluten peptide (THGP) and its combination with ascorbic acid or KBrO₃ were investigated. RESULTS: Molecular analysis of THGP showed a decrease in the high‐molecular‐weight and an increase in the low‐molecular‐weight sodium dodecyl sulfate‐soluble fractions, compared with those of control wheat gluten. The addition of 8% THGP decreased the mixing time and tolerance of the dough, both with and without ascorbic acid or KBrO₃. However, the maximum resistance and extensibility of the rested dough containing 8% THGP, with and without ascorbic acid or KBrO₃, were not significantly different from those of the control dough. The addition of 8% THGP significantly increased the loaf volume of bread baked from non‐frozen dough when combined with 60 ppm ascorbic acid or 30 ppm KBrO₃, but it had a significant effect both with and without ascorbic acid or KBrO₃ on frozen‐dough bread. A large difference in volume was observed between breads made with and without THGP at the oven‐spring, rather than at proofing. CONCLUSION: The addition of 8% THGP increased the loaf volume of bread made from freeze‐damaged dough and this effect increased when THGP was combined with 60 ppm ascorbic acid. Copyright © 2008 Society of Chemical Industry     

GLUTEN QUALITY PREDICTION AND CORRELATION STUDIES IN SPRING WHEATS

ABSTRACT

Gluten, “cohesive, viscoelastic, proteinaceous material prepared as a by‐product of the starch isolation from wheat flour” and the storage and dough‐forming protein of wheat flour, is the key to the unique ability of wheat to suit the production of leavened products. Wet gluten was only affected by wheat varieties, while dry gluten was affected by wheat varieties, crop years and their interaction. The wet and dry gluten ranged 8.0–43.13% and 2.58–14.55%, respectively, and were positively correlated with Zeleny value, sodium dodecyl sulfate sedimentation value and falling number. The gluten content was higher in Pavon, SA 42 and Faisalabad 85, while Zeleny value was higher in GA 02 and C 518, resulting in better gluten quality. Zeleny value was negatively correlated with crude protein content (r = –0.1857*). The lowest amount of wet and dry gluten was detected in Triticale and durum wheats as compared to common wheats. Zeleny value and sedimentation value may be used as indicators of gluten content and quality while working on wheats. The information thus collected will be valuable for cereal chemists and wheat breeders for improvements in their future breeding programs.

PRACTICAL APPLICATIONS

This research work will be a breakthrough and helpful for wheat breeders, growers, millers and bakers for their intended uses as every consumer demand specific wheat quality characteristics for their end products.

     

Pre-Germinated Brown Rice Substituted Bread: Dough Characteristics and Bread Structure

Pre-germinated brown rice (PGBR) having the germ length of 0.5–1.0 mm is produced as a healthy food by immersing the brown rice in water. In this article, various additives were used for making PGBR breads, and suitable combinations of PGBR and additives for breadmaking were evaluated to provide PGBR bread with high functional properties. The 30% of the wheat flour was substituted with PGBR (PGBR 30), and combined additions of phytase (PHY), hemicellulase (HEM) and sucrose fatty acid ester (SE) to PGBR 30 improved the bread qualities with more suitable dough properties, as compared with the sample without their addition. During fermentation, the amounts of gas leaked from the PGBR 30 dough were suppressed by the additions. PHY and HEM hydrolyzed the phytate and hemicellulose in PGBR, and the maturity and extensibility of the PGBR 30 dough were caused by the activated yeast with formed phosphate and decomposed bran, making the large loaf volume and softness of breadcrumbs during storage. In addition, SE accelerated the dough tolerance to mixing or fermentation with the emulsifying ability. Therefore, the combined additions with PHY, HEM, and SE to PGBR 30 improved the dough and bread qualities.     

CHANGES IN APPARENT VISCOSITY AND VITAMIN C RETENTION DURING THERMAL TREATMENT OF BUTTERNUT SQUASH (CUCURBITA MOSCHATA DUCH) PULP: EFFECT OF RIPENING STAGE

ABSTRACT

The effects that ripening stage have on the apparent viscosity and ascorbic acid retention in squash pulp exposed at cooking process were analyzed. Total soluble solids contents were taken as indicative of ripening degree. In the raw material, water contents ranged from 79 to 96%, but no significant differences were observed among samples grouped as unripe, ripe and overripe. The ascorbic acid contents of pulp increase with increases in soluble solids contents. Pulp from unripe and ripe squash had similar apparent viscosity values; however, lower viscosity values were obtained in pulp from overripe squash. During heat treatment, significant changes in the apparent viscosity values of pulp from unripe and ripe squash were observed. Heat penetration properties of squash pulp indicate correlation between the inverse slope of the straight portion in the heat penetration curves on a semilog plot (fh) and thermal diffusivity values (α) with dry matter content, but no correlation was found with squash maturity degree. High ascorbic acid retention (82%) in pulp held for 30 min at 95C was found independently of squash maturation degree.

PRACTICAL APPLICATIONS

Knowing the rheological behaviour and the ascorbic acid retention of butternut squash pulp during cooking process could be used as a valuable information previously to make decisions for use this crop as a food supply.

     

Use of Enzymes to Minimize Dough Freezing Damage

The purpose of this investigation was to study the effect of pentosanase (Pn), glucose oxidase (Gox), and transglutaminase (TG) on frozen dough (−18 °C) and their influence on minimizing the damage caused by frozen storage. Bread characteristics were analyzed on day 0; after 3 and 9 weeks of frozen storage, specific loaf volume, crust color, and crumb texture and structure were analyzed. Dough expansion capacity and dough stickiness, extensibility, and viscoelasticity were determined. Frozen dough with high levels of Gox developed a larger bread volume than control dough (without added enzyme). The damage percentage caused by frozen storage in Gox samples was lower than in control samples, indicating that Gox increased dough strength and counteracted the depolymerization effect of gluten produced by ice crystal formation and the release of reducing substances from dead yeast cells during freezing. Samples with Pn developed a large bread volume after 9 weeks of frozen storage because of the formation of smaller pentosans, which result from Pn enzyme action. These pentosans were located in protein–starch–CO₂ matrix interfaces and increased dough expansion capacity without gas loss, thus allowing a higher expansion during proofing. The intermediate level of TG was the only one to present a larger bread volume from frozen dough than control. The new isopeptidic bonds introduced by TG in the gluten proteins helped to mitigate the damage caused by dough freezing.     

THE EFFECT OF PRETREATMENT OF SHREDDED CELERIAC USING SOLUTIONS OF ENZYMATIC BROWNING INHIBITORS ON THE QUALITY OF MINIMALLY PROCESSED PRODUCT

ABSTRACT

The study investigated the effect of soaking celeriac flakes in solutions containing various concentrations of enzymatic browning inhibitors on the quality of stored minimally processed product. Ascorbic acid (0.2–0.5%), 4‐hexylresorcinol (0.003–0.01%), sodium chloride (0.1–0.5%) and sodium lactate (2–3%) were used as browning inhibitors. On the basis of the conducted tests, it was found that among the applied browning inhibitors, only ascorbic acid had an advantageous effect on the quality of stored celeriac flakes. Along with an increase in its concentration in the solution (0.2–0.5%) used for the pretreatment of the flakes, the value of color parameter a* decreased, while the value of parameter b* increased. At the concentration of ascorbic acid in the solution exceeding 0.25%, flake color in the sensory examination was evaluated as desirable. An increase of ascorbic acid concentration in the solution in the range from 0.2 to 0.4% resulted in a decrease in the total mesophilic and psychrophilic bacteria counts, respectively, by 3 and 1 log cfu/g of the stored product.

PRACTICAL APPLICATIONS

Minimal processing of celeriac provides convenience for consumers and many economic benefits for producers. Minimal processing of celeriac can induce disadvantageous changes in tissue, which may lead to darkening of the flakes and deterioration of product sensory attributes. Moreover, shredded raw material constitutes an excellent medium for the development of microorganisms. This article contains information about the effectiveness of enzymatic browning inhibitors for extending the shelf life of celeriac flakes. We show a range of concentrations of inhibitors, which improve the preservation of color, intrinsic taste and microbial quality of minimally processed celeriac.

     

Enzymatic cross-linking to improve the handling properties of dough prepared within a normal and reduced NaCl environment

This research examines the use of three enzymes [glucose oxidase (GOX), hexose oxidase (HOX), and xylanase (XYL)] and their combinations [GOX–XYL and HOX–XYL] on the dough handling properties of CDC Plentiful and Stettler wheat cultivars prepared at reduced (1.0% wt. by flour) and normal (2.0% wt. by flour) NaCl levels. Properties investigated include dough rheology, stickiness, and ratio of resistance to extension and extensibility. The inclusion of XYL and its combinations with GOX and HOX increased the stickiness, yielded lower dough strength indicated by rheology, and reduced the ratio of resistance to extension and extensibility. The inclusion of oxidative enzymes yielded a stronger dough, where HOX addition to dough had the lowest stickiness values and highest |G*| values, whereas GOX addition led to the highest ratio of resistance to extension—extensibility. NaCl only had minor effects overall on dough strength and stickiness for the cultivars studied. Overall, superior dough handling properties were observed with oxidative enzyme addition (GOX and HOX) suggesting that the increased crosslinking that occurs could aid in improving low sodium bread dough properties.     

Enzymes Action on Wheat–Soy Dough Properties and Bread Quality

High levels of soy flour added to wheat bread produce negative effects on gluten network formation, dough properties, and on bread final quality. The objective of this study was to assess the influence of three enzymes, transglutaminase (TG), glucose oxidase (GOX), and endoxylanase (XYL), on dough properties and final quality of high-protein breads. The addition of TG and GOX increased the mixing stability and maximum resistance of dough, decreased its extensibility, and produced stronger and more consistent dough samples. XYL incorporation produced opposite results. XYL addition and the lowest GOX dose increased bread volume significantly and decreased initial crumb firmness, while high doses of TG (0.3%) produced detrimental effects on bread volume and crumb firmness. In conclusion, XYL and GOX 0.001% addition improved the final quality of soy-fortified breads, but XYL was the best additive to improve dough properties, bread volume, and quality.     

Scanning electron microscopic observations of dough and bread supplemented with Gastrodia elata Blume powder

Dough and bread prepared from wheat flour containing varying amounts of added Gastrodia elata Blume (GEB) rhizome powder [0, 0.5, 1.0, 1.5, and 2.0% (w/w)] were examined by scanning electron microscopy (SEM) during fermentation and baking. The structure of the doughs containing added GEB was found to be related to the protein matrix. Further, it was found that large starch granules and strings of small starch granules play an important role in dough structure. The control dough (no added GEB) had a membrane-like structure, and doughs with 0.5–1.0% added GEB had membrane-like structures that were more developed than those of the control, resulting in increased bread volumes. At 1.5–2.0% GEB levels, however, the doughs tended to have mesh-like structures and result in decreased bread volumes. The dough samples with 0.5 and 1.0% added GEB powder had well-developed gluten matrices with evenly dispersed starch granules. These samples resulted in breads with numerous gas bubble eruptions on their surfaces and consequently in larger loaf volumes than were obtained at other levels of GEB. After the second fermentation, many expanded starch granules were observed and these starch granules were dispersed more evenly than after the first fermentation. In 0.5–1.0% GEB bread, many of the large starch granules had expanded after fermentation, but small starch granules had not. The data obtained in this study suggest that bread baked with 0.5–1.0% GEB exhibits a better loaf volume due to the more complete development of a gluten matrix.     

SLIT RHEOMETER STUDIES OF WHEAT FLOUR DOUGH1

Rheological properties of bread dough having different levels of added gluten (0, 2.5, 5.0 and 7.5%) were measured. The dough was forced through a slit die attached to a cylindrical container. The material functions of interest included steady shear viscosity, first normal stress coefficient in steady shear flow derived from hole pressure measurements and planar extensional viscosity as estimated from entrance pressure drop measurements. These rheological properties were correlated to the loaf volume of the baked bread. Results indicate that the first normal stress coefficient and planar extensional viscosity were affected by the gluten content of the dough and correlated well with the loaf volume. The entrance pressure drop increased with increasing apparent shear rate but entrance correction was found to decrease with apparent shear rate. Water had a greater effect on the rheological properties than gluten content. The Trouton ratio was rather large and ranged between 850 to 2000 at a strain rate of 1s^-1 and decreased with increasing extension rate for most cases.     

Functions of Soy Phosphatidylcholine in Dough and Bread Supplemented with Soy Protein

ABSTRACT: The loaf volume decreased on the addition of soybean protein isolate (SPI) to bread. When phosphatidylcholine was added to the ingredients, including SPI, the adverse effect of SPI on the loaf volume could be counteracted. The addition of phosphatidylcholine showed little effect on the rheological properties of dough. It was shown by confocal microscopy that phosphatidylcholine was associated with gluten in the dough. The function of phosphatidylcholine could not be replaced by phosphatidylethanolamine, phospatidic acid, or lysophospatidylcholine. Phosphatidylcholine showed different effects depending on the phosphatidylcholine molecular species.     

Baking Performance, Rheology, and Chemical Composition of Wheat Dough and Gluten Affected by Xylanase and Oxidative Enzymes

Baking trials were performed with six wheat doughs prepared with xylanase, peroxidase, or glucose oxidase (GOX), and their combinations. Judging dough properties, baking performance, bread volume, and crumb structure, the dough containing xylanase plus peroxidase performed best. Flow relaxation measurements with doughs indicated that peroxidases introduced new transient linkages, whereas glucose oxidase also introduced cross-links permanent on long time scales. Rheological tests and chemical analysis revealed small differences between control and xylanase and/ or peroxidase containing gluten and more pronounced differences for GOX containing gluten. No evidence was found that xylanase specifically removed arabinoxylans from gluten or that peroxidase catalyzed the formation of covalent bonds between arabinoxylans and gluten proteins.     

A STUDY ON THE RELATION BETWEEN ANTHOCYANIN CONTENT AND PRODUCT QUALITY: SHALGAM AS A MODEL BEVERAGE

ABSTRACT

The anthocyanin content and the amount of lactic and acetic acids present in commercial shalgam samples randomly collected from domestic markets were determined both by high‐performance liquid chromatography (HPLC) and spectral measurements. Shalgam samples produced under laboratory conditions were termed as the control group (Group I). The commercial samples were divided into three groups based on their production date: samples stored for 6–9 months as Group II; samples stored for 9–12 months as Group III; and samples stored longer than 12 months as Group IV. The HPLC chromatograms indicated that black carrot was the only source of anthocyanin present in the samples. The acylated to nonacylated anthocyanin ratio increased significantly in Group IV samples, whereas there were no significant differences among the Groups II, III and control (P < 0.05). The % polymeric color negatively correlated to the total anthocyanin content was significantly higher in Group IV samples (P < 0.05). The presence of high acetic acid content might be an indication of added pickle juice to the shalgam samples. The variance of the level of lactic acid found in commercial samples shows up as a problem of incidental enrichment of the lactic acid bacteria.

PRACTICAL APPLICATIONS

Anthocyanin profiles of food materials are unique. Therefore, the anthocyanin profile in a commercial beverage can be used to determine whether there is an adulteration or not. The total anthocyanin content and the ratio of acylated to nonacylated anthocyanins, together with the degree of polymerization and browning index, serve as indicators of the time–temperature history of the product. Applying first‐order degradation kinetics to the anthocyanin under question the initial hypothetical amounts of the juice bearing that anthocyanin can be evaluated. In the specific beverage investigated, shalgam, the level of lactic acid refers to the amount of bulgur used for fermentation. The amount of acetic acid and its negative correlation with the total anthocyanin content can be used as an indicator of adulteration with pickle juice.

     

EFFECT OF OSMOTIC TREATMENT WITH CONCENTRATED SUGAR AND SALT SOLUTIONS ON KINETICS AND COLOR IN VACUUM CONTACT DRYING

ABSTRACT

An experimental study of osmotic dehydration (OD) of selected heat‐sensitive products was carried out in a laboratory‐scale vacuum contact dryer. Cubes of potato and apple were examined as model heat‐sensitive objects. Experiments were conducted at different conduction heat input levels with wall temperatures in the range 35–45C under vacuum and also in pure vacuum without any external heat input. Detailed investigations were carried out of OD on drying performance, product temperature and color of the dried product.

PRACTICAL APPLICATIONS

Osmotic treatment of potato and apple samples using concentrated sugar solution shows better osmotic dehydration as well as drying rate in a vacuum contact drying system. This information may help to select the osmotic agent in any industrial application for faster drying rate in vacuum contact drying specially for food products. Moreover this work shows the analysis to find out the starting point of precipitation of osmotic agent inside the products in terms of drying time, temperature and moisture content. This information will be helpful for critical analysis in osmotic dehydration technique which in turns may help for optimum design.

     

COLOR QUALITY OF ROSE LIQUEUR

ABSTRACT

The effect of pretreatments and soaking conditions on the color quality of rose liqueur was investigated. Results show that (1) most of the anthocyanin in rose petals was dissolved within 48 h of soaking; (2) a longer soaking time led to a lower color quality due to browning ; (3) a base spirit at lower ethanol content extracted more anthocyanin and also resulted in more browning; (4) 50C air‐drying to 20% water content retained 90% of anthocyanins in rose petals; and (5) the soaking of dried petals in the base spirit yielded a product with less browning as compared with that of fresh petals. The process for making rose liqueur with the best color quality was found to be by soaking dried rose petals at a 1:10 ratio (rose petal : ethanol, w/w) in a base spirit containing 30–35% ethanol added with 0.6–0.8% citric acid for 24 h, then diluting the extract to 16% ethanol content.

PRACTICAL APPLICATIONS

This study provides an adequate process for the making of rose liqueur. Pre‐dehydration treatment can be applied on the raw material in the making of various anthocyanin‐containing beverages to improve the color quality. Findings in regard to the effect of ethanol concentration on anthocyanin extraction and the color stability of the product can also be valuable references to wine industry.

     

Optimization of <Emphasis Type="Italic">Aspergillus oryzae</Emphasis> S2 α-amylase,ascorbic acid,and glucose oxidase combination for improved French and composite Ukrainian wheat dough properties and bread quality using a mixture design approach

A simplex-centroid experimental design was used for the optimization of both reducing and oxidizing improvers, namely Aspergillus oryzae S2 α-amylase (Amy), ascorbic acid (Asc), and glucose oxidase (GOD). This optimization was performed to enhance the dough and breadmaking qualities of soft French wheat flour and a composite counterpart that contained 30% Ukrainian wheat flour. Statistically significant correlations were calculated between the W index and textural parameters (e.g., dough chewiness and bread cohesiveness). The findings revealed that while the best mixture for French flour comprised 21.8% of Amy, 41.2% of Asc, and 37% of GOD, for the composite counterpart, it comprised 2.3% of Amy, 66% of Asc, and 31.7% of GOD. These optimized mixtures rearranged soft French wheat flour and its composite counterpart to a good quality and an improved flour texture, respectively. Additionally, they increased the loaf specific volumes of the breads made from soft French wheat flour and its counterpart by 25.8 and 45.43%, respectively, significantly decreased the breads’ susceptibility to microbial contamination, and reclassified the breads as “good” in terms of sensory attributes.