Waste Bread Research Articles

An evaluation based on energy and exergy analyses in SI engine fueled with waste bread bioethanol-gasoline blends

In this study, the operation of a single cylinder, four stroke, SI engine powered by fuels created by blending two different bioethanol with gasoline was evaluated on the basis of energy and exergy analyses. Within the scope of the study, test engine was tested by operating it with fuel blends, prepared by adding both bioethanol, one of them was produced from waste bread and the other, originating from sugar beet, was supplied, to gasoline at different rates by of 5, 10, 15, 85 and 100% under five different engine loads at maximum torque speed, 2500 rpm. The variation of energy and exergy parameters was examined by comparing the blends, prepared to have similar volumetric content, each other and by comparing all with gasoline. As a result of the study, it was determined that the addition of bioethanol had generally decreasing effect on energy loss rate, exergy loss rate and exergy destruction rate. For fuel blends containing low levels of bioethanol, variation of ethanol has created little differences on all energy and exergy parameters but bioethanol type clearly showed its effect when bioethanol rate increased to 85% and 100%. Although waste bread bioethanol could not catch sugar beet bioethanol in terms of thermal efficiency (14.4% for E100b and 16.4% for E100 as load average) and exergetic efficiency (12.9% for E100b and 14.7% for E100 as load average), both bioethanol have been found to improve both thermal efficiency (12.2% for E0) and exergetic efficiency (11.4% for E0) than that of gasoline.

The effect of the stale bread flour addition on flour and bread quality

Abstract In this study, the effect of the flour, which was obtained from stale bread, on flour and bread quality was investigated. The bread that was staled at refrigerator for 7 days was prepared as whole and crumb, and was grinded to convert into flour. The staled whole and crumb bread flours were stored at −18 °C and used to replace 0, 15, 30 and 45% of wheat flour. Then microbiological and physicochemical properties of flours; physical, textural and sensory properties of bread obtained from these composite flours were investigated. We concluded that stale bread flour could be used for bread production at the level of 15%. If the total bread production and consumption is considered, this addition level could provide a significant amount of waste bread recycling each year.

Assessment of waste bread bioethanol-gasoline blends in respect to combustion analysis, engine performance and exhaust emissions of a SI engine

In this study, bioethanol produced from waste bread by fermentation was evaluated as engine fuel comparing with sugar beet bioethanol purchased. Comparison criteria are parameters of combustion analyses, engine performance and exhaust emissions. Therefore, the experiments were carried out in a single cylinder, four stroke, air cooled SI engine fueled with both bioethanol blended with gasoline in different proportions for different test conditions created with different engine load and a constant engine speed. Whether formed with sugar beet or waste bread bioethanol, fuel blends with similar volumetric contents have similar trends in every sense and their position they take relative to pure gasoline is similar. But when the ones with similar content are compared with each other, the differences emerge. These can be summarized as follows: It has been determined that combustion occurs in a shorter time with lower maximum cylinder pressures and maximum heat release rate if the engine runs with fuels containing waste bread bioethanol. In the case of adding waste bread bioethanol, there was a gradual increase in brake specific fuel consumption and a gradual decrease in thermal efficiency compared to sugar beet added fuels. The use of waste bread bioethanol blended with gasoline has seriously positive results in many emissions aspects such that it has less CO up to 70.9%, less HC up to 34.9% and less NOx up to 5.1%, except for the fact that it has more CO2 up to 3.5%.

Waste bread recycling as a baking ingredient by tailored lactic acid fermentation

Food-grade waste and side streams should be strictly kept in food use in order to achieve sustainable food systems. At present, the baking industry creates food-grade waste as excess and deformed products that are mainly utilized for non-food uses, such as bioethanol production. The purpose of this study was therefore to explore the potential of waste wheat bread recycling for fresh wheat bread production. Waste bread recycling was assessed without further processing or after tailored fermentation with lactic acid bacteria producing either dextran or β-glucan exopolysaccharides. When non-treated waste bread slurry was added to new bread dough, bread quality (specific volume and softness) decreased with increasing content of waste bread addition. In situ EPS-production (dextran and microbial β-glucan) significantly increased waste bread slurry viscosity and yielded residual fructose or glucose that could effectively replace the sugar added for yeast leavening. Furthermore, fermentation acidified waste bread matrix, thus improving the hygienic safety of the process. Bread containing dextran synthesized in situ by Weissella confusa A16 showed good technological quality. The produced dextran compensated the adverse effect of recycled bread on new bread quality attributes by 12% increase in bread specific volume and 37% decrease in crumb hardness. In this study, a positive technological outcome of the bread containing microbial β-glucan was not detected. The waste bread fermented by W. confusa A16 containing dextran appears to enable safe bread recycling with low acidity and minimal quality loss.

Efficient bioconversion of waste bread into 2-keto-d-gluconic acid by Pseudomonas reptilivora NRRL B-6

Development of bioprocess routes for production of value-added materials from food waste is very attractive in terms of bioprocess economics and environmental protection. In this study, production of 2-keto-d-gluconic acid, a significant platform chemical, from food waste was performed by Pseudomonas reptilivora NRRL B-6 for the first time. The nitrogen source preference of the strain for 2-keto-d-gluconic acid production under different glucose concentrations in synthetic medium has been elucidated. At higher glucose concentrations, utilization of organic nitrogen source (yeast extract) led to higher product formation while at lower glucose concentration, utilization of inorganic nitrogen source (ammonium chloride) was also very feasible. The results indicated that favorable nitrogen source for 2-keto-d-gluconic acid production can change depending on the glucose concentration. The waste bread hydrolysate (glucose 181.43 g/L, protein 1.21% (w/v)) prepared by sequential application of α-amylase, amyloglucosidase, and protease was utilized in medium formulation at different glucose concentrations. Bread hydrolysate without additional supplements provided higher product formation than the optimum medium prepared with the hydrolysate. Utilization of 50 g/L CaCO3 led the maximum product formation. The maximum 2-keto-d-gluconic acid production from waste bread was 142.81 g/L with the productivity of 3.02 g/L/h and molar yield of 0.95. The proposed approach in this study confirms that waste bread as a sole source of nutrients can be valorized for microbial production of various industrially relevant platform chemicals.

Effect of temperature and nitrogen supplementation on bioethanol production from waste bread, watermelon and muskmelon by Saccharomyces cerevisiae

This study was undertaken to investigate the effect of temperature (25 °C and 30 °C) and nitrogen supplementation (with 20 g/L peptone or without) on bioethanol production from waste bread, watermelon and muskmelon feedstocks by Saccharomyces cerevisiae. Nitrogen addition resulted in higher ethanol yields at both temperatures. Fermentation at 30 °C produced a higher ethanol yield than at 25 °C. The highest ethanol yield of 0.502 gethanol /g fermentable sugar, at 98.22% of the theoretical maximum, was obtained from the fermentation of muskmelon juice at 30 °C with nitrogen supplementation. Ethanol yields at both temperatures were significantly different (p < 0.05) between the trials with nitrogen and without nitrogen supplementation for watermelon and muskmelon but not for waste bread hydrolysate. On the other hand, ethanol yields showed significant differences (p < 0.05) at 25 °C and 30 °C for all feedstocks with nitrogen and without supplementation.

Enzymatic hydrolysis of waste bread by newly isolated Hymenobacter sp. CKS3: Statistical optimization and bioethanol production

Microbial hydrolytic enzymes are relevant biotechnological products that can be applied in various industries. In this study, we have tested the activity of hydrolytic enzymes of a newly isolated Hymenobacter sp. CKS3 strain and showed, for the first time, that members of Hymenobacter genus have still unexplored hydrolytic potential. Crude hydrolytic enzymes, produced by the strain CKS3 on a waste medium, were incorporated into a process of bioethanol production using waste bread. The conditions for bread hydrolysis were optimized using statistical design. Waste bread hydrolysate obtained under optimal conditions (100.73 h of hydrolysis, waste bread concentration 20.36% and agitation speed 200 rpm) contained 19.89 g/l of reducing sugars. A high performance liquid chromatography of hydrolyzed waste bread samples showed that the main components of the hydrolysate were dextrins, maltotriose, maltose and glucose. When using this substrate and waste baker’s yeast for ethanol production under non-optimized conditions 1.73% of ethanol was produced. The results of this study showed that a newly isolated Hymenobacter sp. CKS3 can be utilized for enzymatic hydrolysis and bioethanol production in a process relying on waste materials. Furthermore, it was demonstrated that members of Hymenobacter genus have a significant and currently unexplored potential for bio-based industrial applications.

A research on fuel properties of bioethanol produced from waste bread

In this study, fuel properties of two bioethanol fuel, one produced from waste bread (E100b) and the other originated from sugar beet (E100) and base gasoline (E0) were treat as a subject. It was investigated that the properties of fuel blends formed by mixing both bioethanol with gasoline in the same proportions as 5, 10, 15, 85%. The evaluation was based on the fuel properties, which are thought to have the most influence on engine operation, such as density, purity, kinematic viscosity, octane number, heating value. Waste bread based- bioethanol has been found to cause an increasing effect on the density, kinematic viscosity, while decreasing the heating value to some extent. The results showed that differences in fuel properties among both bioethanol that are thought to be related to purity can be ignored for fuel blends with low bioethanol content.

Karbon Kaynağı Olarak Atık Ekmeklerin Kullanılmasıyla Elde Edilen Ksantan Gamların Teknolojik Özellikleri ve Model Gıda Olarak Pudingteki Performansı

Technological properties of aqueous solutions of xanthan gums produced by various Xanthomonas species using waste bread (WB) hydrolyzate as a carbon source to reduce the overall product cost and to utilize waste bread were investigated and compared with commercial xanthan gum. While the highest water holding capacity was detected in the commercial xanthan gum, oil holding capacity was higher in xanthan gums from X. campestris DSM 19000 and X. axonopodis pv. begoniae than commercial gum. Pudding samples were prepared by the gums obtained and Ostwald de Waele model was successfully described the behavior. The highest K value were obtained by the sample without gum addition as 161.2 Pa.sn, this was followed by the sample with the gum from X. axonopodis pv.begoniae with 139.3 Pa.sn and X. hortorum pv.pelargonii with 133.2 Pa.sn . n values varied between 0.12 and 0.49 and increased with the addition of the gum. Therefore, this study showed that the pudding samples prepared with the gums from X. axonopodis pv. begoniae and X. hortorum pv. pelargonii isolates using waste bread as substrate were found to be more resistant to shear rate and angular frequency and had a more robust gel structure.

Combining submerged and solid state fermentation to convert waste bread into protein and pigment using the edible filamentous fungus N. intermedia

Waste streams from ethanol and bread production present inexpensive, abundant and underutilized renewable substrates that are highly available for valorisation into high-value products. A combined submerged to solid state fermentation strategy was studied using the edible filamentous fungus Neurospora intermedia to biotransform ethanol plant residues ‘thin stillage’ and waste bread as substrates for the production of additional ethanol, biomass and a feed product rich in pigment. The fungus was able to degrade the stillage during submerged fermentation, producing 81 kg ethanol and 65 kg fungal biomass per ton dry weight of thin stillage. Concurrently, the second solid state fermentation step increased the protein content in waste bread by 161%. Additionally, 1.2 kg pigment per ton waste bread was obtained at the best conditions (6 days solid state fermentation under light at 95% relative humidity at 35 °C with an initial substrate moisture content of 40% using washed fungal biomass to initiate fermentation). This study presents a means of increasing the value of waste bread while reducing the treatment load on thin stillage in ethanol plants.

Anaerobic Digestion of Food Waste with Unconventional Co-Substrates for Stable Biogas Production at High Organic Loading Rates

Anaerobic digestion (AD) is widely considered a more sustainable food waste management method than conventional technologies, such as landfilling and incineration. To improve economic performance while maintaining AD system stability at commercial scale, food waste is often co-digested with animal manure, but there is increasing interest in food waste-only digestion. We investigated the stability of anaerobic digestion with mixed cafeteria food waste (CFW) as the main substrate, combined in a semi-continuous mode with acid whey, waste bread, waste energy drinks, and soiled paper napkins as co-substrates. During digestion of CFW without any co-substrates, the maximum specific methane yield (SMY) was 363 mL gVS−1d−1 at organic loading rate (OLR) of 2.8 gVSL−1d−1, and reactor failure occurred at OLR of 3.5 gVSL−1d−1. Co-substrates of acid whey, waste energy drinks, and waste bread resulted in maximum SMY of 455, 453, and 479 mL gVS−1d−1, respectively, and it was possible to achieve stable digestion at OLR as high as 4.4 gVSL−1d−1. These results offer a potential approach to high organic loading rate digestion of food waste without using animal manure. Process optimization for the use of unconventional co-substrates may help enable deployment of anaerobic digesters for food waste management in urban and institutional applications and enable increased diversion of food waste from landfills in heavily populated regions.

Facile preparation of activated carbon foam via pyrolysis of waste bread under CO2 atmosphere

Activated carbon foam was prepared via direct pyrolysis of waste bread (WB) under CO2 atmosphere. The product was characterized by N2 adsorption/desorption and Fourier transform infrared spectroscopy (FTIR). The preparation process was investigated online by a thermogravimetric analyzer coupled with FTIR (TG-FTIR). The adsorption isotherms of methylene blue (MB) by the product were investigated. The experimental data demonstrated that the product had a high surface area of 1575 m2 g−1 and a total pore volume of 0.883 cm3 g−1. Thermal decomposition of polymers in WB mainly occurred between 200 and 500 °C, leading to the release of carbonyl compounds, aliphatic hydrocarbons, alcohols, and furans. The dominant CO2 activation process started at above 800 °C. The MB adsorption equilibrium data followed Langmuir model with a monolayer adsorption capacity of 403 mg g−1. This study provides a reference for the utilization of WB as a promising precursor of activated carbon foam adsorbent, which has highly porous structure and excellent floatability in water.

Xanthan gum biosynthesis using Xanthomonas isolates from waste bread: Process optimization and fermentation kinetics

Waste bread hydrolysate was used as a biosource for xanthan production by various isolates and standard bacteria (Xanthomonas campestris DSM 19000). Influence of operational conditions used in the process of xanthan production were evaluated through yield of xanthan, rheological properties of aqueous solution and fermentation kinetics. For the highest yield and viscosity, optimum conditions including carbon source concentration, inoculum volume and agitation rate were determined for 4 different strains by using response surface methodology. The highest gum yield as 14.3 g/L was obtained by Xanthomonas axonopodis vesicatoria and the highest conversion rate of waste bread to xanthan gum was found as %14.1 for Xanthomonas hortorum pv. pelargonii. Whereas, the highest aqueous solution viscosity of gum produced from standard bacteria was 11.2 Pa.sn at glucose ratio of 4%, inoculum volume of 5% and mixing rate of 225 rpm. For fermentation kinetics; the values of growth associated parameters revealed that they are mostly affected by the rate of xanthan gum production and substrate consumption. In general, optimum conditions to obtain the highest xanthan gum yield were different from that to achieve the highest viscosity. This study shows the potential of waste bread hydrolyzates as the promising economic carbon source for xanthan gum production.

BioH2 production from waste bread using a two-stage process of enzymatic hydrolysis and dark fermentation

The potential of bioH2 production using waste bread via a two-stage process was examined. In the first stage, the waste bread was utilized by Aspergillus awamori and Aspergillus oryzae through solid state fermentation to generate glucoamylase and protease which were then utilized to hydrolyze the waste bread to produce the waste bread hydrolysate. The highest starch conversion of 96.6% and glucose yield of 0.521 g glucose/g waste bread were achieved within 24 h. In the second stage, the waste bread hydrolysate was utilized for bioH2 production by Biohydrogenbacterium R3. The maximum H2 yield of 103 mL H2/g waste bread could be obtained. The proposed two-stage bioprocess, which was able to increase the nutrient conversion efficiency and H2 production from organic solid wastes, should be a promising way for bioH2 production in industrial application.

Optimization of Enzymatic Hydrolysis of Waste Bread before Fermentation

Finding of optimal hydrolysis conditions is important for increasing the yield of saccharides. The higher yield of saccharides is usable for increase of the following fermentation effectivity. In this study optimal conditions (pH and temperature) for amylolytic enzymes were searched. As raw material was used waste bread. Two analytical methods for analysis were used. Efficiency and process of hydrolysis was analysed spectrophotometrically by Somogyi-Nelson method. Final yields of glucose were analysed by HPLC. As raw material was used waste bread from local cafe. Waste bread was pretreated by grinding into small particles. Hydrolysis was performed in 100 mL of 15 % (w/v) waste bread particles in the form of water suspension. Waste bread was hydrolysed by two commercial enzymes. For the liquefaction was used α‑amylase (BAN 240 L). The saccharification was performed by glucoamylase (AMG 300 L). Optimal conditions for α‑amylase (pH 6; 80 °C) were found. The yield of total sugars was 67.08 g∙L-1 (calculated to maltose). As optimal conditions for glucoamylase (pH 4.2; 60 °C) were found. Amount of glucose was 70.28 g∙L1. The time of waste bread liquefaction was 180 minutes. The time of saccharification was 90 minutes. The results were presented at the conference CECE Junior 2014.

Simultaneous dark fermentative hydrogen and ethanol production from waste bread in a mixed packed tank reactor

Simultaneous dark fermentative hydrogen and ethanol production from waste bread in a mixed packed tank reactor (MPTR) was investigated. Waste bread was first hydrolyzed by the produced enzymes to generate the waste bread hydrolysate which was subsequently introduced to the MPTR for dark fermentative hydrogen and ethanol production. The optimal hydrogen and ethanol production rates were 15.01 mmol/(h·L) and 23.25 mmol/(h·L) when the organic loading rate reached 32 g/(L·d). The unit hydrogen and ethanol production were 4.87 mmol hydrogen/g waste bread and 7.54 mmol ethanol/g waste bread, respectively. This study provided a new direction for economic and efficient hydrogen and ethanol production from waste bread.

Biohydrogen production from waste bread in a continuous stirred tank reactor: A techno-economic analysis

Biohydrogen production from waste bread in a continuous stirred tank reactor (CSTR) was techno-economically assessed. The treating capacity of the H2-producing plant was assumed to be 2 ton waste bread per day with lifetime of 10years. Aspen Plus was used to simulate the mass and energy balance of the plant. The total capital investment (TCI), total annual production cost (TAPC) and annual revenue of the plant were USD931020, USD299746/year and USD639920/year, respectively. The unit hydrogen production cost was USD1.34/m3 H2 (or USD14.89/kg H2). The payback period and net present value (NPV) of the plant were 4.8years and USD1266654, respectively. Hydrogen price and operators cost were the most important variables on the NPV. It was concluded that biohydrogen production from waste bread in the CSTR was feasible for practical application.

Bread wastage and recycling of waste bread by producing biotechnological products

Bread wastage and recycling of waste bread by producing biotechnological products

Utilization of waste bread to produce fermentable sugars and rheological behavior during hydrolysis

Utilization of waste bread to produce fermentable sugars and rheological behavior during hydrolysis

Waste Bread as a Biomass Source: Optimization of Enzymatic Hydrolysis and Relation between Rheological Behavior and Glucose Yield

Amongst the many forms of food waste, bread is a major contributor to the problem. Two aims of this research investigate waste breads potential of being a bioresource for the production of fermentable sugars which are precursor of valuable bioproducts by fermentation process: finding optimum substrate, water and enzyme ratio to produce the highest amount of fermentable sugars and investigating the rheological behavior of the system during hydrolysis. Two stage waste bread hydrolysis was performed with enzymes α-amylase and amyloglucosiades and response surface methodology was used to optimize substrate, water and enzyme ratio. Discovery Hybrid Rheometer-2 (TA Instruments) fitted with a parallel-plate geometry was used to investigate steady flow viscosity of the slurry during hydrolysis. 99 % of theoretical maximum glucose yield, a main fermentable sugar, is achieved by optimizing enzymatic hydrolysis conditions of waste bread at liquefaction and saccharification stages. Just after the addition of α-amylase enzyme, substantial decrease is observed in viscosity and Casson apparent yield stress of the slurry. During saccharification stage, glucose yield increases dramatically while viscosity of the slurries is very low and does not change considerably. The results imply that utilizing high concentrations of waste bread as a feedstock to produce fermentation products offers economic benefits without causing high power consumption, excessive wear on equipment, and reduced conversion which are generally expected consequences for high-solid processing.