Bread Crust Research Articles

Liquefaction performances of bread crusts in subcritical water

Hydrothermal liquefaction of bread crusts in subcritical water were performed in a micro-batch reactor. The influences of temperature (300 – 360 °C) and residence time (10-30 min) on bio-oil yield, boiling point distribution and functional groups in bio-oil were investigated. The results showed that bio-oil yield increased with increasing temperature and reaction time. Maximum bio-oil yield of 22.69wt% was obtained at 360 °C, 30min. The longer reaction time promoted the degradation of diesel to jet fuel and naphtha. The naphtha (C7-10) and jet fuel (C11-C15) increased to 29.9%, 51.82% at 30min from 20.49% and 36.14%, respectively. FT-IR analysis showed that esters, ketones, amides, acids and aldehydes were present in the bio-oil.

Effect of baking conditions on the physical properties of bread incorporated with green coffee beans (GCB)

Most of nutrients can be found in normal breads but there is lack of antioxidant rich polyphenolic compounds. Green coffee bean (GCB) is chosen as functional ingredients to be incorporated in the bread as it contains high amount of phenolic acid namely chlorogenic acid which contributed to antimutagenic, anticarcinogenic and antioxidant activities. Therefore, GCB was chosen as natural sources in order to enrich the wheat bread with their phenolic antioxidant’s characteristics. The objective of this study is to investigate the effect of concentration of green coffee bean, baking temperature, and baking time on the physical properties of the incorporated bread. The physical properties such as moisture content, volume, colour, and texture were analysed. The data obtained were statistically analysed using Analysis of Variance (ANOVA). The results show that the incorporation of GCB has a positive influence on the physical properties of the bread especially on moisture content and volume. The factors with the largest effect on the moisture content were the baking temperature and GCB concentrations (p < 0.05). The use of high baking temperature causes higher moisture content and volume of bread after baking. While for bread crust and crumb colour, it was observed that increasing the baking temperature and time resulted in dark crust colour and reduced the colour saturation. For crumb colour, the addition of GCB powder caused a slight decreased in lightness and yellowness, whereas the redness of bread was almost unchanged. Nevertheless, the incorporation of green coffee bean had a little influence on the texture of the bread. High hardness of the bread demonstrated from the high baking temperature and high baking time. From optimization process, it could be concluded that the optimum baking temperature was found at 180°C, baking time of 40 minutes and GCB concentration of 1 wt% in order to get the better quality of the bread. In conclusion, GCB has a great potential as functional ingredient in bread. The addition of GCB does not only affect the antioxidant properties of the bread but also increase the quality of the bread itself.

Effects of various brans on quality and volatile compounds of bread

The present study aimed to evaluate the effect of various bran sources, including wheat, barley, and rice, on the quality and volatile compounds of Egyptian ‘balady’ bread (Fino). The protein, fat, and total carbohydrates content of the studied brans ranged from 8.49 to 14.16%, 2.16 to 8.12%, and 34.38 to 85.06%, respectively. The mi- neral composition and colour parameters of the brans were also evaluated. The substitution of wheat flour with 10%, 20%, and 30% of different brans resulted in decreased loaf volume and specific volume, and increased loaf weight. A significant decrease in colour parameters (L, a, and b) of the bread crust and crumb were observed in all the sam- ples. The addition of bran at three concentrations showed a remarkable increase in the total phenolic content of the bread samples, compared to the control. The antioxidant activity of the bread samples fortified with brans showed the following order: RB (rice bran) &gt; BB (barley bran) &gt; WB (wheat bran), as determined by the DPPH and β-carotene assays. Thirty-six volatile compounds identified in the bread samples using GC-MS included 5 alcohols, 6 pyrazines, 2 acids, 9 aldehydes, 5 ketones, 3 esters, and 6 sulphur-containing compounds. Alcohols were the predominant vola- tile constituents accounting for 58.3; 61.57; 59.08; and 56.15% in the control and in the bread samples prepared with bran from rice, barley, and wheat, respectively.

Quantitative Analyses of Key Odorants and Their Precursors Reveal Differences in the Aroma of Gluten-Free Rice Bread and Wheat Bread.

Rice flour is one of the most important raw materials in gluten-free products. However, the aroma of gluten-free rice bread is less accepted by consumers than that of commercial wheat bread. Therefore, 18 selected aroma compounds were determined in rice and wheat breads by stable isotope dilution assays (SIDA) to elucidate differences in the sensory characteristics, concentrations, and odor activity values (OAVs). The OAVs of most aroma compounds varied greatly between a rice and a wheat bread. In particular, 2-aminoacetophenone with a grape-like, medicinal aroma was characteristic for rice bread crumb and crust, while maltol was only relevant in wheat bread crust. Ehrlich pathway products varied in their concentration between the bread crumbs and were correlated with the contents of their corresponding free amino acid precursors in the flours and doughs. The analysis of rice flour revealed that only a few aroma compounds were retained in the bread. Consequently, the bread making process has a high relevance in aroma compound formation. In a comparison of breads prepared from fresh and stored rice flour, hexanal was identified as an important indicator for aging in rice bread and flour.

Dietary fiber content, texture, and in vitro starch digestibility of different white bread crusts

Different types of white bread are sold and widely consumed worldwide. The objective of this study was to evaluate the starch digestibility in the crust of different white breads. Three popular commercial white breads were analyzed for dietary fiber (DF), thermal properties, texture, starch hydrolysis and resistant starch (RS) contents, in freshly baked and stored samples. The DF content in fresh crusts “as eaten” (6.8–7.2%) represents about 25% of the recommended daily consumption. The hardness and elasticity, RS and DF contents increased upon storage, associated with incomplete starch gelatinization and retrogradation, corroborated by the thermal analysis. The hydrolysis rate suggested that the structural arrangement of the starch components in the crust, possibly due to the low water content resulting from evaporation during baking and upon storage, restricts the susceptibility to digestive enzymes action. Consumption of bread crust may be suggested as a means to increase the DF intake.

Comparison of the Aroma Profiles of Intermediate Wheatgrass and Wheat Bread Crusts.

The aroma profiles of bread crusts made from intermediate wheatgrass (Thinopyrum intermedium) and whole wheat (Triticum aestivum) flours were compared. Based on gas chromatography/mass spectrometry/olfactometry analysis, twenty-four odorants were identified and further quantified. The concentrations of seventeen compounds were significantly different between intermediate wheatgrass and whole wheat bread crusts, of which sixteen compounds were higher in the whole wheat sample. The aroma profiles of the bread samples were subsequently characterized using sensory descriptive analysis (DA) and indicated that the roasted attribute was perceived at a significantly higher intensity in the whole wheat sample due to a greater amount of Maillard reaction compounds. Alternatively, bran and green notes were perceived at higher intensities in the intermediate wheatgrass sample, however they were not attributed to the presence of specific compounds but rather to a change in the aroma composition. Aroma recombination DA of the whole wheat and intermediate wheatgrass aroma models was similar to the original aroma profiles of the bread samples, demonstrating the sensory relevance of the identified odorants.

QUALITY ASPECTS OF PAN BREAD PREPARED BY PARTIAL SUBSTITUTION OF WHEAT FLOUR WITH DEFATTED RICE BRAN

In recent years, there is a growing interest towards the consumption of highly nutritive and healthy food to fulfill the consumer demands. Rice bran, a by-product of rice milling industry, is a rich source for dietary fiber, protein, minerals, fat, vitamins and antioxidants and hence can be utilized as functional ingredient. Therefor the current study focused on using defatted rice bran (DRB) as partial substitute of wheat flour in the preparation of pan bread. The quality attributes of pan bread were evaluated. The results indicated that composite pan bread made with DRB had higher (p≤0.05) moisture, crude protein, crude fiber and ash contents than control bread.Increasing the substitution level with DRB resulted in lower (p≤0.05) loaf volume, height and specific volume compared to control. The crust and crumb colors of composite bread were darker, more reddish and yellowish colored than control. Textural analysis of composite bread exhibited higher (p≤0.05) hardness, chewiness and gumminess and lower (p≤0.05) cohesiveness, springiness and resilience than control bread. Control bread as well as bread made with 5% DRB showed the highest (p≤0.05) overall acceptability scores. Also, bread made with 10% DRB was overall acceptable by panelists. The results revealed that DRB could be incorporated in bread formula up to 10% to produce organoleptically acceptable and more nutritious bread compared to control.

Different baking conditions may produce breads with similar physical qualities but unique starch gelatinization behaviour

This study evaluated the impact of baking conditions (time, temperature and steam) on the local heating rate and its consequences on bread attributes. Dough was baked under different temperatures (160, 190 and 220 °C) and time (9, 12, 15 and 20 min), with the temperature rise monitored throughout the process. Macroscopic quality and macromolecular aspects of bread were analysed. A higher heating rate was observed for bread crumb baked with steam introduced at the beginning of baking and for bread crust baked without steam, at higher temperatures. Although different local heating rates were observed with the various baking conditions, the conditions which produced bread with similar quality aspects were identified. However, a similar trend was not observed for starch gelatinisation, which was unique to each baking condition. Consequently, baking aspects (time, temperature, steam) can be used to modify or to maintain bread characteristics, in which macromolecular changes are unique only due to different thermal development and mass transfer characteristics.

Optimization of Quality Properties of Gluten-Free Bread by a Mixture Design of Xanthan, Guar, and Hydroxypropyl Methyl Cellulose Gums.

The objective of this study was to investigate, by means of a D-optimal mixture design, the combined effects of hydroxypropyl methyl cellulose (HPMC), xanthan (XG), and guar (GG) gums on physicochemical, rheological, and textural properties of gluten-free batter and bread. For each of the quality properties measured, a two-factor interaction model was fitted, and the significance of its terms was assessed by analysis of variance. Sticky batters were produced with a combination of high dose of GG (0.60%), high-intermediate dose of HPMC (3.36%), and low dose of XG (0.04%). Combinations of high XG dose (0.60%) and intermediate doses of HPMC (3.08%) and GG (0.32%) rendered GF breads of greater specific volume, while lower bread crust luminosity was obtained with combinations of high GG dose (0.60%), low XG dose (0.04%), and high-intermediate HPMC dose (3.36%). Combinations of high-intermediate HPMC dose (3.36%), high GG dose (0.60%), and low XG dose (0.04%) produced both softer crumbs and bread slices of more open visual texture. By using a desirability function that maximized specific volume while minimizing crust luminosity, crumb hardness, and mean cell density, the optimization of hydrocolloids mixture rendered a value of 0.54, for a combination of 0.24% XG, 0.60% GG, and 3.16% HPMC.

Evaluation of thermal inactivation parameters of Salmonella in whole wheat multigrain bread

This study was conducted to validate a simulated commercial whole wheat multigrain bread baking process at 375 °F (190.6 °C) oven temperature for 35 min to inactivate Salmonella, and to determine the thermal inactivation parameters of a 7-serovar Salmonella cocktail in whole wheat multigrain bread dough. A ≥5-log CFU/g reduction in Salmonella population was achieved by 15 min, and no viable Salmonella was detected after enrichment plating by 16 min. The aw of the bread crumb (0.96) after baking and 60 min of cooling was similar to that of pre-baked bread dough, whereas the aw of bread crust decreased to 0.81 at the end of baking and cooling. The D-values of the Salmonella cocktail in bread dough were 59.6, 20.0 and 9.7 min at 50, 52 and 55 °C, respectively; and the z-value was 6.5 °C.

Identification of the Key Aroma Compounds in Gluten-Free Rice Bread.

Rice flour is commonly used as a raw material in the preparation of gluten-free bread. However, compared to wheat bread, its aroma is different and often not accepted by consumers. Aroma profile analyses of the crumb and crust of freshly baked rice bread indicated a strong rice-like flavor but lower intensities of the typical roasty wheat bread odor qualities. By application of aroma extract dilution analyses (AEDA), the most odor active compounds in both rice and wheat bread samples were characterized. In addition, two batches of rice flour were used. In particular, 2-aminoacetophenone and 4-vinylphenol reached high flavor dilution (FD) factors in the rice bread samples but were not detected in wheat bread. In the rice bread crust 1-octene-3-one, ( E)-2-nonenal, and 4-methylquinazoline reached significantly higher FD factors than in the wheat bread crust, while those of maltol and 2-methoxy-4-vinylphenol were significantly lower. In a stored rice flour and in the corresponding rice bread, lipid degradation products such as hexanal were more intense compared to fresh rice flour. Finally, five aroma-active compounds, namely, 2-butyl-2-heptenal, 2-propyl-2-octenal, 4-hydroxy-2-octenoic acid lactone, 4-hydroxy-2-nonenoic acid lactone, and 4-methylquinazoline, were identified for the first time in rice-containing products.

Effect of rice, pea, egg white and whey proteins on crust quality of rice flour-corn starch based gluten-free breads

Gluten-free bread crusts are known for their crumbly texture, light colour, poor nutritional quality and weak aroma. The objective of this research was to improve crust quality of gluten-free breads by the addition of rice, pea, egg white and whey proteins to the bread formulation in two levels (5% and 10%). Moisture, water activity, thickness, microstructure, texture, colour and volatile compounds were measured. A 99% negative significant correlation between spatial frequency of structural ruptures and crust moisture content was found. Results from texture analysis indicated that animal and 10% pea protein crusts were less crispy than control. Moreover, crust microstructure of animal protein bread was very different from control and vegetal protein crusts. Animal and vegetal protein crusts showed darker colour than control and the darkest was obtained from whey protein inclusion. With respect to the volatile profiles, rice protein crusts had the highest content of 2-acetyl-1-pyrroline while whey protein crusts had high level of pyrazines, which was in concordance with their dark colour. However, whey protein and, above all, rice protein also increased the content of volatile compounds from lipids oxidation. Thus, the suitable proportion between rice and whey protein should be found to achieve the most pleasant aroma.

Bakery Science of Bread and the Effect of Salt Reduction on Quality: A Review

Salt or sodium chloride is widely used in most homemade dishes or processed foods. It can be considered as a crucial ingredient because, without adding salt most dishes or food products may have less flavor, become tasteless and not appetizing. The addition of salt can provide salty taste or can even mask the bitter taste. It is also widely used as a preserving agent and can increase product’s shelf life. Bread is widely consumed and serves as a staple food for certain countries. Not only that, bread is one of the world’s oldest foods and is said to be the largest contributor of salt in our diet. While bread is believed to supply the major percentage of daily salt intake, reduction of salt in this product can assist in reducing the consumption of salt in human’s diet. Salt is also found to have detrimental impact on human health as it can cause cardiovascular diseases. Nevertheless, the salt reduction in bread is not easy to apply as salt play important roles in bread-making and its reduction can affect the quality of bread. Salt in bread has been observed to improve dough-making process, enhances the flavor of bread and produces nice brown colour of the bread's crust through Maillard reaction. Besides that, salt also helps in improving the texture, decreasing staling and increasing the microbial shelf life of the bread. This article explains the bakery science of bread by discussing the effect of salt reduction on bread quality.

Isolation and quantification in food of 6-(2-formyl-5-methylpyrrol-1-yl)-l-norleucine (“rhamnolysine”) and its precursor 3,6-dideoxy-l-mannosone

In the Maillard reaction (non-enzymatic browning), reducing carbohydrates react to 1,2-dicarbonyl compounds that may combine with the e-amino group of lysine to form characteristic pyrrole compounds such as pyrraline and formyline in a Paal–Knorr reaction. In the present study, the Maillard reaction of the rare sugar l-rhamnose was studied. The l-rhamnose-derived dehydration product 3,6-dideoxy-l-mannosone (3,6-DDM) was synthesized and structurally characterized via NMR. Mainly the α-pyranose is formed in aqueous solution. 2-(2′(S),3′(S)-Dihydroxybutyl)quinoxaline was synthesized for the first time and used as a standard for quantification of 3,6-DDM in food. Analysis of 3,6-DDM after conversion to the respective quinoxaline via RP-HPLC–MS/MS revealed concentrations not exceeding 23 µg/kg in food items such as coffee and brewing malt. Moreover, the Paal–Knorr reaction product of 3,6-DDM with lysine, namely 6-(2-formyl-5-methylpyrrol-1-yl)-l-norleucine (rhamnolysine) was synthesized for the first time by reaction of N-α-Boc-lysine and 3,6-DDM and purified by semi-preparative ion-exchange chromatography followed by characterization by NMR and HPLC–MS/MS. Rhamnolysine was analysed in 42 food items by RP-HPLC–MS/MS in the MRM mode after enzymatic hydrolysis. The highest concentration of the compound was found in rye bread crust (4.9 mg/kg). It appears mainly in foods that are highly heat-treated, roasted or fried.

THE EFFECT OF THE USING CORN FLOUR LEVEL AND ADDITIVE TYPE ON QUALITY OF CORN BREAD

The effects of different levels of corn flours and additives on traditionally produced (in the Black Sea Region) corn bread’s quality parameters were studied; the breads containing different levels of corn flour (0%, 10%, 20%, 30%, 40%, 50%, 75%, 100%) in flour formulation were produced as two different additives type [(10% whole egg, 10% butter and 5% yogurt combination and without addition (control)]. As a result, the additive, one of the main variation sources, was found to have a high very significant (p≤0.01) effects on mass, volume, specific volume, L* and a* color values of crumb, and crust of bread and the moisture values of crumb (0, 1 and 2. days). Besides, the same variation source was also found to have a high very significant (p≤0.01) effects on sensorial appearance, porosity, texture, volume, color of crust, color of crumb, chewiness, taste, aroma, overall acceptability, and hardness, cohesiveness, elasticity, chewiness, and gumminess parameters measured on 0, 1 and 2 days. parameters. Also corn flour variant had a highly significant (p≤0.01) effects on the mass, volume, specific volume, L* and a* color values of crust, a*color value of crumb, the moisture values of crumb and sensorial appearance, porosity, texture, volume, color of crust, color of crumb, chewiness, aroma, and overall acceptability, hardness (0, 1, and 2. day), cohesiveness (day 1), elasticity (day 0), chewiness (day 0, and 2), gumminess (day 0, 1, and 2) and significant (p≤0.05) effects on cohesiveness (day 0, and 2) and cohesiveness (day 2) parameters. Also analyze of variance indicated that the interaction between addition and amount of corn flour was significantly (p≤0.01) in most traits.

Effect of amino acids on Maillard reaction product formation and total antioxidant capacity in white pan bread

SummaryMaillard reaction products (MRPs) can be an important dietary antioxidant source. Bread is the most popular bakery product; however, limited information is available on the antioxidant activities of MRPs generated during bread‐baking. This paper reports the effect of different amino acids on bread properties, melanoidin formation and antioxidant activities. Totally six amino acids at four different levels were evaluated. Increasing the amount of amino acid led to darker bread crust, higher melanoidin content and stronger antioxidant activity. Among the six amino acids, bread with glycine had the highest melanoidin content and ABTS radical scavenging activity up to 1079.77 ± 8.43 μmol TE mg−1. Bread with lysine had the highest DPPH radical scavenging activity up to 281.97 ± 10.52 μmol TE mg−1. Bread with alanine had the highest crust metal chelating activity compared with others. Adding certain dietary amino acids is a potential approach to enhance the antioxidant capacity of bread products.

Kinetic study of the thermal inactivation of Lactobacillus plantarum during bread baking

Live probiotics can be supplemented to bread as functional ingredients. The viability of probiotics in bread needs to be sufficient to exert a beneficial effect on human health. To maximize the viability, a kinetic study on the inactivation of probiotics during baking was carried out. The thermal inactivation of Lactobacillus plantarum P8 during bread baking was evaluated with rate-dependent kinetic models. The influences of temperature, moisture content, drying rate, and temperature variation rate on the inactivation kinetics were studied explicitly. A kinetic model , which included temperature (T), moisture content (X), and temperature variation rate (dT/dt) as variables, was found to best describe the concave and sigmoidal survival curves of probiotics in bread crust and in crumb during baking, respectively. The drying rate (dX/dt) was of little influence on the kinetics. The application of the proposed model is limited to baking processes, but could be used to maximize the survival of probiotics in bread products.

Optimization of composite dough for the enrichment of bread crust with antifungal active compounds

The production of composite or double-layer (DL) bread was optimized to reduce the amount of the chemical preservative calcium propionate. It was validated using sourdough (SD) in the crust (0–80 g/100 g crust dough). Par-baked (PB) and fully baked (FB) breads were evaluated based on their shelf-life extending, bread technological and sensorial properties. The shelf-life of PB bread was increased with ≥60 g SD/100 g crust dough for air packaged and ≥20 g SD for modified atmosphere packaged (MAP) breads. Use of 60 g SD/100 g crust dough was sufficient to achieve the same level of preservation with or without MAP. Par-baked and fully baked bread were mould free for respectively 7 and 30 days using 60 g sourdough in 100 g crust dough. Specific volume decreased for PB bread containing 40–60 g SD/100 g crust dough and for FB bread with 80 g SD/100 g crust dough. Accordingly, crumb hardness was impaired under the latter conditions.

From the Chief Executive and News

From the Chief Executive and News

Quality and sensory profiling of gluten free bread as a function of quinoa, corn and xanthan content: Statistical analysis and modeling study

In the study, the effect of compositional parameters (Xanthan, Corn flour and quinoa flour content) on sensory characteristics and image features of gluten free bread were evaluated. Results showed, addition of quinoa and corn flour significantly decreased L* value and increased a* value of crust and crumb of gluten free bread. Also, increased percentage of corn flour has led to decreased amount of FDL* that indicates the area appears less nonhomogeneous on surface of gluten- free bread. The results also showed that using complete flour of quinoa causes softness in bread due to the presence of bran and networking, therefore, resulting in increased contrast, homogeneity and entropy, and decreased energy and correlation of produced breads. The results of sensory analysis showed that all samples containing quinoa flour have higher overall acceptance score than that of the control treatment. Correlation analysis showed a good linear relationship between image features and overall acceptance of gluten- free bread. Results showed that the optimized Adaptive Neuro-Fuzzy Inference System (ANFIS model) provide best accurate prediction method for overall acceptance of gluten-free bread (R2= 0.994 and MSE= 0.0015) and it could be a useful tool in the food industry to design and develop novel products.