Baker's Yeast Industry Research Articles

Valorization of Baker Yeast Industry Waste in Agriculture by Improving Germination and Growth of Barley and Pea.

Industrial waste still present an environmental danger for the nature and survival of all living beings. Among these toxic products, the focus has been on liquid effluents from the baker's yeast industry that cause real environmental problems mainly due to their pollutant load and the release of unpleasant odors. In order to minimize these hazards and to take advantage of these wastes for the sake of our environment, the present work consists on valorizing effluents from the baker's yeast industry on barley (Hordeum vulgare) and pea (Pisum sativum), two important agricultural products of Tunisian north-west. Results showed that this waste is characterized by its richness in organic matter, and the presence of proteins traces with high chemical and biochemical oxygen demand (COD and BOD5) values. Diluted effluent at a dose of 2.5mg/g significantly improves germination of both plant seeds by germination index (GI) calculation, to reach a maximum of 190 ± 17% and 150 ± 14% for barley and pea, respectively. In fertigation experiment, the use of a lower dose of .62mg/g of diluted effluent promotes plant length to reach 52 ± 4cm and 45 ± 1.4cm, respectively, for H. vulgare and P. sativum. Gas chromatography coupled to mass spectrometry (GC-MS) analysis after derivatization showed significant enhancement of auxin production in pea treated with .62mg/g of cream compared to control with a concentration of 10.60 ± .81 and 8.16 ± .43ng/gFW, respectively. In another experiment, the irrigation of pea plants with furfural, as major compound of cream, promotes length and auxin production to reach 9.89 ± .56ng/gFW for a furfural dose of .31mg/g. This leads us to valorize baker's yeast effluent as an environment-friendly natural product in pea and barley agricultural and give insight to its mode of action.

Evaluation of modified dried vinasse as an alternative dietary protein source for broilers

AbstractThe increase in poultry production and the high cost of soybean led to the search for alternative protein sources. One of these sources is vinasse, a by‐product of the baker's yeast industry. Modified dried vinasse (MDV) can be produced for use in poultry nutrition by making some improvements in vinasse. Therefore, the present study aimed to examine the effect of the usage of MDV in broiler diets. A total of 192 daily male Ross 308 chicks were randomly assigned to four groups. MDV was included at the levels of 0%, 2%, 4%, and 6% in the diets for 42‐day trial. Linear significant improvements in the final weight, body weight gain, feed efficiency, and digestibility were seen with increasing MDV levels. The use of MDV caused a significant reduction in feed consumption. The relative weight percentages of abdominal fat and serum cholesterol concentration were reduced linearly with increases in MDV levels. MDV inclusion linearly decreased the malondialdehyde concentration, but increased 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity in breast meat significantly. The protein content in breast meat was increased with MDV. Cecal beneficial microorganisms and serum IgG levels were increased linearly with MDV. In conclusion, results suggested that MDV could be a feasible option for alternative protein sources for broilers.

Compressed Baker's Yeast: Mapping Patents on Post-Fermentation Processes.

In the baking industry, fresh yeast is generally available as a compressed paste containing about 70% moisture. While much literature has been published on its growth conditions in fermentation tanks, little information may be obtained on the final steps of baker's yeast production. In this review, 226 patents were found on the separation of yeast cells from spent growth media as well as its dewatering, forming, and packaging in the compressed form. The latter corresponded to 21% of 1096 unique families of patented inventions filed worldwide between 1787 and 2014 on the production of fresh baker's yeast. Patent specifications disclosed key technical information not available in scientific journals. Particularly between 1890 and 1960, highly specific equipment such as centrifugal separators, rotary vacuum filters, and extruding and cutting units were proposed. Compressed yeast may contain small amounts of processing aids, including water-absorbing agents such as starch and salt, as well as plasticizing and whitening agents. Any variation in yeast solids and moisture contents will affect its gassing power and keeping properties. Disposal and proper treatment of very large volumes of spent growth media will remain a major challenge to the baker's yeast industry.

Start‐up and steady‐state results of a UASB reactor treating high pH baker's yeast molasses wastewater for methane production

AbstractBACKGROUNDThe baker's yeast industry is a major market and due to the intensified production large quantities of waste are generated. Wastewater from the baker's yeast industry with high content of molasses was treated anaerobically in an upflow anaerobic sludge blanket (UASB) reactor for the production of methane (CH4).RESULTSThe molasses wastewater obtained from industry had a high pH value around 8.0 ± 0.5, which remained constant during the experimental period. The system was operated at an organic loading rate (OLR) of 2.4–7.65 g of volatile solids per liter per day (g VS L−1 d−1) and the best results were observed at 4 g VS L−1 d−1, where methane production exceeded 350 L CH4 kg−1 VS. Anaerobic chemical oxygen demand removal was also examined and it was found that for the latter conditions of optimum OLR, it was more than 35%. VFA analysis revealed that acetic acid concentration in the reactor was more than 25 mmol L−1 even under optimum conditions.CONCLUSIONSThe tested hydraulic retention time (HRT) values did not affect methane production, unlike the OLR. The increased acetic acid concentration in the UASB reactor and the high pH were credited to the inhibition of aceticlastic microorganisms. © 2016 Society of Chemical Industry

Post-treatment of molasses wastewater by electrocoagulation and process optimization through response surface analysis

Molasses wastewater is a high strength effluent of food industry such as distilleries, sugar and yeast production plants etc. It is characterized by a dark brown color and exhibits a high content in substances of recalcitrant nature such as melanoidins. In this study, electrocoagulation (EC) was studied as a post treatment step for biologically treated molasses wastewater with high nitrogen content obtained from a baker's yeast industry. Iron and copper electrodes were used in various forms; the influence and interaction of current density, molasses wastewater dilution, and reaction time, on COD, color, ammonium and nitrate removal rates and operating cost were studied and optimized through Box Behnken's response surface analysis. Reaction time varied from 0.5 to 4 h, current density varied from 5 to 40 mA/cm2 and dilution from 0 to 90% (v/v expressed as water concentration). pH, conductivity and temperature measurements were also carried out during each experiment. From preliminary experiments, it was concluded that the application of aeration and sample dilution, considerably influenced the kinetics of the process. The obtained results showed that COD removal varied between 10 and 54%, corresponding to an operation cost ranging from 0.2 to 33 euro/kg COD removed. Significant removal rates were obtained for nitrogen as nitrate and ammonium (i.e. 70% ammonium removal). A linear relation of COD and ammonium to the design parameters was observed, while operation cost and nitrate removal responded in a curvilinear function. A low ratio of electrode surface to treated volume was used, associated to a low investment cost; in addition, iron wastes could be utilized as low cost electrodes i.e. iron fillings from lathes, aiming to a low operation cost due to electrodes replacement. In general, electrocoagulation proved to be an effective and low cost process for biologically treated molasses-wastewater treatment for additional removal of COD and nitrogen content and color reduction. Treated effluent samples with good quality were produced by EC, with COD, NH4–N and NO3–N concentrations of 180, 52 and 2 mg/l respectively. Response surface analysis revealed that optimized conditions could be established under moderate molasses wastewater dilution, (e.g. 45%), at 3.5 h treatment time and 33 mA/cm2 current density.

Source Based Characterization and Pollution Profile of a Baker's Yeast Industry

AbstractBaker's yeast industry has significant effects on environment due to significant water consumption and high strength wastewater production. Effluents from baker's yeast industry are characterized by high concentrations of biological oxygen demand (BOD5), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), total dissolved solids (TDS), sulfate, and dark brown color. The aim of this study is to provide a detailed quantitative and qualitative identification and characterization of the wastewater sources from different processes of a baker's yeast industry. It is identified that the most polluted wastewater components of the facility are coming from rotary drum filter and evaporation process. However, the highest pollution loads is identified as tank and equipment cleaning effluent due to very high flow rate from this source. The efforts should be on the way to minimize the water usage for the tank and equipment cleaning process, and to recycle less polluted waste streams back to the process.

Optimization of Leavening Activity of Baker's Yeast During the Spray-Drying Process

Leavening activity is an important quality index in the baker's yeast industry. In this work, Taguchi's experimental design was used to investigate the effect of important factors on the leavening activity of Saccharomyces cerevisiae during spray drying. Feed rate and inlet air temperature are the most important factors in spray drying of baker's yeast. The amount of starch as a processing aid also has a considerable effect on the leavening activity of the yeast.

Production of biofertilizers using baker's yeast effluent and their application to wheat and barley grown in north Sinai deserts

Effluent from the baker's yeast industry was experimented on as a culture medium for the growth and biomass production of diazotrophs. The effluent supported good growth of Azotobacter chroococcum, Enterobacter agglomerans and Klebsiella pneuomoniae, Azospirillum brasilense, Bacillus polymyxa and Pseudomonas putida and strongly proposed for biofertilizers production of associative diazotrophs. Slurry preparations containing natural polymers, e.g. Arabic gum (5%), pero-dextrin (20%), starch granules (10%) or gelatine (20%) were impregnated with cells of tested diazotrophs. With storage, entrapped cells of B. polymyxa were viable up to 160 days, while gradual decreases in Azospirillum numbers were recorded. Pero-dextrin, a by-product of the starch industry, was selected as the appropriate biocarrier accommodating diazotroph cells and maintaining prolonged survival rates and nitrogenase activity. Cell cultures of A. brasilense, A. chroococcum, B. polymyxa, E. agglomerans and P. putida were equally mixed and entrapped into pero-dextrin slurry biofertilizer formulation named as “BIOGRAMINA”. Tested diazotrophs successfully survived (ca. 108 cfu ml−1) in such formulation up to 6 months at both ambient and cold temperatures. The response of wheat and barley to “BIOGRAMINA” in the presence or absence of N fertilizers was evaluated in greenhouse and field trials. Highest total biological yields were recorded for inoculated plants simultaneously supplemented with rational N fertilizer dose.

Decolorization of a baker's yeast industry effluent by Fenton oxidation

Baker's yeast industry is an important industry in Turkey. Molasses is used as a raw material, which is an end product of sugar industry. Baker's yeast industry effluents contain various pollutants and are generally characterized with high chemical oxygen demand (COD), TKN, dark color and non-biodegradable organic pollutants. The objective of this study was to investigate the decolorization and the removal of non-biodegradable organic pollutants measured as mainly DOC, SUVA 254, SUVA 280 and COD parameters. Fenton oxidation was applied to biologically pre-treated effluent of full-scale wastewater treatment plant. Jar test method was used to determine the best operating conditions. The 600 mg/L H 2O 2/600 mg/L Fe 2+ dosage was quite enough to obtain a high color removal efficiency of 97%. However, the best Fe 2+/H 2O 2 dosage was 1200 mg/L Fe 2+/800 mg/L H 2O 2 at pH 4 and in reaction time of 20 min for mineralization of DOC and COD. For these conditions, the maximum color removal efficiency was obtained as 99%, maximum DOC and COD removal efficiencies were obtained as 90 and 88%, respectively. Also, SUVA 254 and SUVA 280 values decreased.

Advanced Oxidation of Biologically Pretreated Baker's Yeast Industry Effluents for High Recalcitrant COD and Color Removal

The aim of this study was to investigate the effectiveness of chemical oxidation by applying ozonation, ozonation with hydrogen peroxide and Fenton's processes for decolorization and residual COD removal of biologically pretreated baker's yeast industry (BYI) effluents. Baker's yeast industry effluents characterizing with high COD, TKN, dark color, and non-biodegradable organic pollutants. The batch tests were performed to determine the optimum operating conditions including pH, O3, H2O2, and FeSO4 dosages, molar ratio of Fe2+/H2O2 and reaction time. It was noticed that H2O2 significantly reduced the reaction times for the same ozone dosages; however, COD and color removals were not remarkable. In the Fenton's oxidation studies, the removal efficiencies of COD and color for 30 min reaction time for three different types of BYI effluents were found about 86 and 92%, respectively. Experimental results of the presented study have clearly indicated that the Fenton's oxidation technology is capable to fate almost all parts of the organics which consist of both soluble initial and microbial inert fractions of COD for baker's yeast effluents. Effluents from the Fenton's oxidation process can satisfy effluent standards for COD and color in general.

Toxicity assessment on combined biological treatment of pharmaceutical industry effluents

This paper describes the wastewater characterization and aerobic/anaerobic treatability (oxygen uptake rate and biogas production measurement) of chemical-synthesis based pharmaceutical industry effluents in a nearby baker's yeast industry treatment plant. Preliminary experiments by the industry had indicated strong anaerobic toxicity. On the other hand, aerobic treatability was also uncertain due to complexity and unknown composition of the wastewater. The work in this study has indicated that the effluents of the pharmaceutical industry can be treated without toxicity in the aerobic stage of the treatment plant. Methanogenic activity tests with anaerobic sludge from the anaerobic treatment stage of the wastewater treatment plant and acetate as substrate have confirmed the strong toxicity, while showing that 30 min aeration or coagulation with an alum dose of 300 mg/l is sufficient for reducing the toxicity almost completely. Powdered activated carbon, lime and ferric chloride (100-1,000 mg/l) had no effect on reduction of the toxicity. Consequently, the pharmaceutical industry was recommended to treat its effluents in the anaerobic stage of the nearby baker's yeast industry wastewater treatment plan at which there will be no VOC emission and toxicity problem, provided that pretreatment is done.

Treatment of biologically treated effluents from baker's yeast industry by membrane and ozone technologies

This paper presents pilot‐scale membrane treatment results performed on biologically treated effluents from fermentation industry and ozone oxidation on concentrates from the same membrane treatment system. The results obtained from the ultrafiltration (UF) and/or the reverse osmosis (RO) systems indicate that membrane treatment are very effective for COD, Color, NH3‐N and conductivity removal. Ozone oxidation of the membrane concentrates was tested to increase biodegradability of the wastes. The initial ratios of Biochemical oxygen demand (BOD5) to Chemical oxygen demand (COD) were increased significantly by applying chemicaloxidation with O3 and O3 + H2O2.

Common anaerobic treatability of pharmaceutical and yeast industry wastewater

The purpose of this study is to demonstrate the feasibility of anaerobic treatment of pharmaceutical and baker's yeast industry effluents in a joint treatment system. Anaerobic treatability studies have been performed in a lab-scale upflow anaerobic sludge blanket reactor (UASBR). The experimental study has been carried out for 333 days. The influent COD's during the experimental study were about 10,000 mg/l. Pharmaceutical wastewater has a 5% of inhibition on the COD removals at the dilution rate of 1/100 or more in the joint anaerobic treatment with baker's yeast industry effluents. Maximum inhibition of 10% on the average was observed when the system was characterized with acclimation periods. The study has shown that, following the solvent extraction with pre-aeration process, a common anaerobic treatment can be applied to baker's yeast industry wastewater and to pharmaceutical industry effluents.

Common anaerobic treatability of pharmaceutical and yeast industry wastewater

The purpose of this study is to demonstrate the feasibility of anaerobic treatment of pharmaceutical and baker's yeast industry effluents in a joint treatment system. Anaerobic treatability studies have been performed in a lab-scale upflow anaerobic sludge blanket reactor (UASBR). The experimental study has been carried out for 333 days. The influent COD's during the experimental study were about 10,000 mg/1. Pharmaceutical wastewater has a 5% of inhibition on the COD removals at the dilution rate of 1/100 or more in the joint anaerobic treatment with baker's yeast industry effluents. Maximum inhibition of 10% on the average was observed when the system was characterized with acclimation periods. The study has shown that, following the solvent extraction with pre-aeration process, a common anaerobic treatment can be applied to baker's yeast industry wastewater and to pharmaceutical industry effluents.

The effect of anaerobic pre-treatment on the inert soluble COD of fermentation industry effluents

The objective of this study is to determine the inert soluble COD of wastewaters from the fermentation industry. In this context, a series of experiments were performed for various effluents from baker's yeast industry including raw process wastewater, anaerobic pre-treatment plant effluents, domestic and washing waters mixture. The inert COD ratio (SISO) for the raw effluents from baker's yeast industry was determined as 0.1. This ratio was in the range of 0.20 to 0.30 for the anaerobically pre-treated effluents. TheSISO ratios for the wastewater simulating the effluent of the existing full-scale aerobic treatment plant have varied from 0.18 to 0.48. Such a large variation has been originated from the operating conditions of the existing full-scale anaerobic treatment plants. The higher volumetric loading rates and shorter sludge retention times correspond the lower SISO ratios for the full-scale anaerobic treatment systems in general.

The effect of anaerobic pre-treatment on the inert soluble COD of fermentation industry effluents

The objective of this study is to determine the inert soluble COD of wastewaters from the fermentation industry. In this context, a series of experiments were performed for various effluents from baker's yeast industry including raw process wastewater, anaerobic pre-treatment plant effluents, domestic and washing waters mixture. The inert COD ratio (S1/S0) for the raw effluents from baker's yeast industry was determined as 0.1. This ratio was in the range of 0.20 to 0.30 for the anaerobically pre-treated effluents. The S1/S0 ratios for the wastewater simulating the effluent of the existing full-scale aerobic treatment plant have varied from 0.18 to 0.4S. Such a large variation has been originated from the operating conditions of the existing full-scale anaerobic treatment plants. The higher volumetric loading rates and shorter sludge retention times correspond the lower S1/S0 ratios for the full-scale anaerobic treatment systems in general.

Influence of Substrate Distribution on Productivities in Computer Controlled Baker's Yeast Production

In recent years considerable emphasis has been placed on the application of computer control to substrate feeding in baker's yeast production. Many investigators have studied the dynamics of different control loops and also first steps have already been taken to optimize the control algorithms. As far as the experimental verification of different strategies is concerned, the published work is, however, restricted to laboratory scale only. From current practice in baker's yeast industry which is most often based on open loop control with fixed schedule for carbon substrate addition, it is well known that mixing of substrate is playing an important role. The effects of the dynamics of mixing process in mechanicaly stirred tanks upon the performance of baker's yeast fermentation with fixed schedule have been investigated earlier by using a circulation model (Bajpai and Reuss, 1982). In the present contribution this framework is used in conjunction with a closed computer control of carbon substrate feeding based on exhaust air analysis. From experimental results for computer controlled fermentation in 10 and 2 000 l scale a decrease of productivity with increasing circulation times of liquid is observed. These results can be confirmed with the model calculations.