Corn Steep Water Research Articles

Assessment of physical pre-treatments for the recovery of biosurfactants in corn steep water prior to advanced membrane-based water treatment

The aim of this work is to evaluate different physical pre-treatments for corn steep water (CSW) to obtain a cleaner, concentrated water stream in biosurfactants for further advanced water treatment, involving not only the decontamination of water but also the complete recycling of CSW. Three physical treatments were tested: i) decantation, ii) centrifugation, and iii) vacuum filtration under different temperatures. After these pre-treatments, several parameters were evaluated. Results showed that centrifugation at 4 °C (C4L) is the best alternative for concentrating biocompounds as it produced a cleaner stream with a greater lightness (from 0.45 to 92.9–96.2) and lower turbidity than decantation or vacuum filtration but with a higher content in biosurfactants. Moreover, it was observed that acidification of C4L produced a decrease in the surface tension properties of CSW compatible with the precipitation and/or denaturalization of lipopeptides and proteins, whereas basification did not produce any relevant effect. Acidification or basification during pre-treatment of CSW was therefore dismissed with the recommendation of performing a simple centrifugation step at 4 °C as a pre-treatment, prior to recovering bioactive compounds using advanced membrane water treatments.

Recovery of biocompounds from corn steep water by a hybrid filtration and liquid-solid process

Recovery of biocompounds from corn steep water by a hybrid filtration and liquid-solid process

Integration of filtration and liquid-solid process with MN100 resin for corn steep water purification

Integration of filtration and liquid-solid process with MN100 resin for corn steep water purification

Simultaneous production of xylitol and arabitol by Candida tropicalis fermentation improving agro-industrial wastes valorization

Xylitol and arabitol are sugar alcohols with similar properties and applications. Although the biotechnological production of xylitol is already being explored, its coproduction with arabitol is still in the early stages. This study aimed to improve the coproduction of xylitol and arabitol by Candida tropicalis from sugarcane bagasse hemicellulosic hydrolysate. The most promising results were achieved with 2.2 g L−1 nitrogen, obtained by mixing 80% yeast hydrolysate and 20% corn steep water. For fermentations conducted in a bioreactor, the concentrations of xylitol (52.1 g L−1) and arabitol (4.2 g L−1) were 65 and 3.7 times higher, respectively, than those reported in the literature for similar processes, with productivities and yields of 0.24 g L−1 h−1 and 0.74 g g−1 for xylitol and 0.02 g L−1 h−1 and 0.43 g g−1 for arabitol. These results show promise for the coproduction of sugar alcohols from sugarcane bagasse hemicellulosic hydrolysate by C tropicalis.

Statistical optimization of the fermentation factors for increased biorefinery of corn-steep water effluent to lactic acid by Enterococcus faecium strain WH51-1

Organic waste bioprocessing for production of useful products are increasing due to fossil fuel depletion, problems with waste management, and the requirement for biodegradable plastics. Lactic acid (LA) is important in foods, polymer beverages, cosmetics, and medicine applications. However, the main challenge in the large-scale processing of LA is the enhanced production and productivity using low-cost resources. In this study, Enterococcus faecium WH51-1, a newly obtained thermo-alkali tolerant LA bacterium, was used for LA production from corn-steep water (CSW) as raw material. The optimal culture conditions and medium components were established. Different concentrations of yeast extract (YE) and pH values were investigated with highest LA production of 48.2 ± 2.7 g/L at a yield of 0.89 ± 0.04 g/g-consumed sugars and a productivity of 0.50 ± 0.03 g/L.h at pH 8.5 without YE supplementation. A central composite design (CCD) was utilized to determine the high LA concentrations at optimal values for the process variables (sugar concentrations, temperature, inocula sizes, pH value, and YE concentration). The model was realized with an acceptable fit. The optimization of the factors was carried out by normal probability plots, interaction-plots, incorporating effect plots, analysis of variance (ANOVA), surface plots, Pareto charts, and contour plots. All the parameters were influenced at a 5% significance level. Additionally, some of the possible interactions between these parameters also influenced the production process. A regression model was suggested and fitted the experimental data very well. The results of this work investigated that LA synthesized of the optimized-fermentation conditions was 10% greater than classical optimization methods. This study presented a green “free nutrient” and cost-effective utilization of corn steep effluent as a cheap alternative substrate for biorefinery to lactic acid.Graphical

Evaluation of Calcium Alginate-Based Biopolymers as Potential Component of Membranes for Recovering Biosurfactants from Corn Steep Water

Corn steep water (CSW) is a complex agro-food stream that is used as a source of cost-competitive biosurfactants, since they are produced spontaneously in the steeping process of corn, avoiding production costs. Nevertheless, the extraction of biosurfactants from CSW using sustainable processes is still a challenge. Consequently, the use of calcium alginate membranes could present a novel and sustainable technology for recovering biosurfactants from aqueous streams. Therefore, the aim of this work is to evaluate calcium alginate-based biopolymers, without and with the presence of grape marc as an additive, as a key component of membranes for the recovery of biosurfactants in corn steep water. Biosurfactants are present in CSW, together with other inorganic solutes and biomolecules, such as organic acids, sugars, cations, anions as well as metals. Hence, the competition of these mentioned compounds for the active sites of the calcium alginate-based biopolymers was high. However, they showed a good adsorption capacity for biosurfactants, recovering around 55 ± 2% and 47 ± 1%, of biosurfactants from CSW using both calcium alginate-based biopolymers, with and without biodegraded grape marc. Regarding adsorption capacity, it was 54.8 ± 0.6 mg biosurfactant/g bioadsorbent for the biopolymer containing grape marc, and 46.8 ± 0.4 mg biosurfactant/g bioadsorbent for the calcium alginate-based biopolymer alone. Based on these results, it could be postulated that the formulation of green membranes, based on calcium alginate-based polymers, could be an interesting alternative for the recovery of biosurfactants from aqueous streams including CSW.

Use of Corn-Steep Water Effluent as a Promising Substrate for Lactic Acid Production by Enterococcus faecium Strain WH51-1

Various challenges facing the industrial production of bio-based lactic acid (LA) such as cost of raw materials and nitrogen sources, as well as contamination risk by mesophilic and neutrophilic producers, should be overcome for the commercial production. This study aimed to investigate the feasibility of corn steep water (CSW) as a raw material for LA production using a newly thermo-alkali-tolerant lactic acid bacterium. The physicochemical characteristics of CSW were investigated. The high carbohydrates, proteins, amino acids, vitamins, essential elements, minerals, and non-protein nitrogenous compounds content confirmed that the CSW is a promising substrate for LA production. Out of 67 bacterial isolates, Enterococcus faecium WH51-1 was selected based on its tolerance to high temperatures and inhibitory compounds (sodium metabisulfate, sodium chloride, sodium acetate, and formic acid). Fermentation factors including sugar concentration, temperature, inoculum size, and neutralizing agents were optimized for LA production. Lactic acid concentration of about 44.6 g/L with a high yield (0.89 ± 0.02 g/g) was obtained using 60 g/L of CSW sugar, inoculum size 10% (v/v), 45 °C, and sodium hydroxide or calcium carbonate as a neutralizing agent. These results demonstrated the potential of strain WH51-1 for LA production using CSW effluent as raw material.

Characterization and Cytotoxic Effect of Biosurfactants Obtained from Different Sources.

In this work, five biosurfactant extracts, obtained from different sources, all of them with demonstrated antimicrobial properties, were characterized and subjected to a cytotoxic study using mouse fibroblast cells (NCTC clone 929). Biosurfactant extracts obtained directly from corn steep water (CSW) showed similar surfactant characteristics to those of the extracellular biosurfactant extract produced by Bacillus isolated from CSW and grown in tryptic soy broth, observing that they are amphoteric, consisting of viscous and yellowish liquid with no foaming capacity. Contrarily, cell-bound biosurfactant extracts produced from Lactobacillus pentosus or produced by Bacillus sp isolated from CSW are nonionic, consisting of a white powder with foaming capacity. All the biosurfactants possess a similar fatty acid composition. The cytotoxic test revealed that the extracts under evaluation, at a concentration of 1 g/L, were not cytotoxic for fibroblasts (fibroblast growth > 90%). The biosurfactant extract obtained from CSW with ethyl acetate, at 1 g/L, showed the highest cytotoxic effect but above the cytotoxicity limit established by the UNE-EN-ISO10993-5. It is remarkable that the cell-bound biosurfactant produced by L. pentosus, at a concentration of 1 g/L, promoted the growth of the fibroblast up to 113%.

Fungistatic and Fungicidal Capacity of a Biosurfactant Extract Obtained from Corn Steep Water.

Biosurfactants are surface-active compounds that are produced by microorganisms, which in addition to their surfactant capacity, can possess interesting antimicrobial activities that are used in their incorporation into the agrifood industry. In this work, the preservative capacity of a novel biosurfactant extract obtained from a residual stream of the corn-milling industry was evaluated against two different fungi (Aspergillus brasiliensis and Candida albicans) under different biosurfactant concentrations (0.33–0.99 mg/mL), temperatures (4–40 °C), and incubation times (5–11 days). All the assays started with the same concentration of fungi (2 × 106 CFU/mL). The results showed that temperature played an important role in the bactericidal and fungistatic effects of this biosurfactant extract. It was observed that at a low biosurfactant concentration (0.33 mg/mL) and low or high temperatures in the range tested, this biosurfactant extract possessed an important fungicidal effect (complete inhibition) on A. brasiliensis, while at intermediate temperatures, it achieved a fungistatic effect (50% of inhibition). Regarding C. albicans, it was observed that this strain was more resistant than A. brasiliens, although it was possible to achieve growth inhibitions of 76.3% at temperatures of 40 °C after 8 days of incubation with a biosurfactant concentration of 0.99 mg/mL. This work supports the possible application of biosurfactants extracted from corn steep water as preservatives and antimicrobial agents against fungal contaminations on agrifood products.

Extraction, separation and characterization of lipopeptides and phospholipids from corn steep water

This is the first work about the fractionation, separation and identification of different bioactive compounds contained in a multifunctional biosurfactant extract, obtained from corn steep water through a liquid–liquid extraction with chloroform. In this extract, phospholipids (21%) were precipitated with acetone and identified by electrospray ionization mass spectrometry (ESI-MS/CID), detecting a characteristic signal at 758 m/z that corresponds with phosphatidylethanolamine and phosphatidylcholine. In this extract, major biomarkers at 879 and 933 m/z and small signals between 1000 and 1500 m/z were also detected, corresponding with lipopeptides (25%) with different molecular weights. For determining the amino acids and fatty acids of these lipopeptides, the biosurfactant extract, obtained from corn steep water, was subjected to acid hydrolysis. Subsequent, the fatty acids contained in the hydrolysate were extracted with ether and analyzed by gas chromatography–mass spectrometry (CG-MS), discovering the presence of C16 and C18 fatty acids. Additionally, the hydrolyzed peptides, solubilized in the aqueous phase, were analized using ESI-MS/MS/CID, identifying glutamic acid/glutamine, aspartic acid/asparagine, glycine, alanine, arginine, proline and leucine/isoleucine. Free fatty acids (49.1%) were also quantified by titration with KOH. Remarkably, all the compounds identified in this multifunctional biosurfactant have high interest for obtaining more compatible formulations in different industries.

Study of biosurfactant extract from corn steep water as a potential ingredient in antiacne formulations

Background This is a novel work that includes the use of a biosurfactant extract obtained from corn milling industry (named BS-CSW), with antimicrobial activity, as ingredient in formulations to treat acne vulgaris. Methodology With this purpose, it was established an incomplete experimental design with 3 independent variables, based on the concentration of non-nano zinc oxide (ZnO) (0–2%), BS-CSW (0–5%) and salicylic acid (0–2%). Results This design allowed to obtain a theoretical model that calculates the inhibitory effect on Cutibacterium acnes (also named Propionibacterium acnes) for any formulation carried with the ingredients appointed before. It was observed a clear synergetic effect on the inhibition of C. acnes between ZnO and BS-CSW, in absence of salicylic acid. This fact allowed to reduce the concentration of ZnO, giving more ecofriendly and biocompatible formulations. Conclusions It was observed that the biosurfactant extract, in formulations with intermediate concentration of ZnO (1%), possess an inhibitory effect on C. acnes considerably higher than ZnO alone and similar to ZnO (1%) with salicylic acid (1%). This fact demonstrates the enormous potential of this bioactive extract in antiacne formulations.

A Multifunctional Biosurfactant Extract Obtained from Corn Steep Water as Bactericide for Agrifood Industry.

The increase of crop production along with stricter requirements on food security have augmented the demand of new and eco-friendly bactericides. Most of the bactericides used at the moment consist of persistent organic substances, representing a risk for environmental and human health. For instance, agriculture bactericides used for crop protection includes copper-based, dithiocarbamate and amide bactericides, which are not biodegradable, resulting in the necessity of further research about the production of new active principles that attack microorganisms without producing any harmful effect on human health or environment. The biosurfactant extract evaluated in this work as a bactericide, is obtained from corn steep water, a residual stream of corn wet milling industry, which is fermented spontaneously by probiotic lactic acid bacteria that possess the capacity to produce biosurfactants. In previous works, it has been demonstrated that this biosurfactant extract is able to promote the growth of Lactobacillus casei in drinkable yogurts, though its antimicrobial activity against pathogenic strains has not been evaluated at the moment. The results obtained in this work have proved that this biosurfactant extract is effective as bactericide against Pseudomonas aeruginosa and Escherichia coli, at concentrations of 1 mg/mL, opening the door to its use in agrifood formulations for reducing the use of chemical pesticides and preservatives.

Biodegradability Study of the Biosurfactant Contained in a Crude Extract from Corn Steep Water

AbstractOver the last few years, the global biosurfactant market has raised due to the increasing awareness among consumers, for the use of biological or bio‐based products. Because of their composition, it can be speculated that these are more biocompatible and more biodegradable than their chemical homologous. However, at the moment, no studies exist in the literature about the biodegradability of biosurfactants. In this work, a biosurfactant contained in a crude extract, obtained from a corn wet‐milling industry stream that ferments spontaneously in the presence of lactic acid bacteria, was subjected to a biodegradation study, without addition of external microbial biomass, under different conditions of temperature (5–45 °C), biodegradation time (15–55 days), and pH (5–7). For that, a Box–Behnken factorial design was applied, which allowed to predict the percentage of biodegradation for the biosurfactant contained in the crude extract, between the range of the independent variables selected in the study, obtaining biodegradation values between 3 and 80%. The percentage of biodegradation for the biosurfactant was calculated based on the increase in the surface tension of samples of the crude extract. Furthermore, it was also possible to predict the variation in t1/2 for the biosurfactant (time to achieve the 50% of biodegradation) under different conditions.

Quality Evaluation of Soycorn Yoghurt Fermented with Starter Culture and Corn Steep Water

Quality Evaluation of Soycorn Yoghurt Fermented with Starter Culture and Corn Steep Water

Isolation and characterization of a microorganism that produces biosurfactants in corn steep water

ABSTRACTIn this work a Bacillus strain with capacity to produce biosurfactants was isolated from commercial corn steep water (CSW). The identification of this bacterium was based on phenotypic characteristics. This is a Gram-positive Bacillus, macroscopically catalase-negative, that possesses high mobility and forms terminal endospore. The colonies formed by the isolated Bacillus strain are characterized by a creaming, dull and glistening phenotype with a small point-like elevation in the center. Regarding its antimicrobial activity, the isolated Bacillus strain was effective against Candida albicans and Staphylococcus aureus observing, in the presence of pathogenic strains, a phenotype dissociation, switching the colonies from a whitish to yellowish pigmentation. The isolated microorganism, contrarily to other Bacillus strains, has the ability to produce extracellular and cell-bound biosurfactants. The analyses revealed that both biosurfactant extracts are similar to the lipopeptide biosurfactant produced by Bacillus subtilis.

Feasiblity of Bioethanol Production from Cider Waste.

Wastewater from cider factories (losses during transfers, products discarded due to quality policies, and products returned from the market) exhibit a Chemical Oxygen Demand greater than 170,000 mg O2/l, mainly due to the ethanol content and carbohydrates that are added to obtain the finished product. These effluents can represent up to 10% of the volume of cider produced, and they must be treated to meet environmental regulations. In this work, a process was developed, based on alcoholic fermentation of the available carbohydrates present in ciders. The impact of inhibitors at different pH, size and reuse of inoculums and different nutrient supplementation on the ethanol yield were evaluated. The use of a 0.5 g/l yeast inoculum and corn steep water as the nutrient source allowed for depletion of the sugars in less than 48 h, which increased the content of ethanol to more than 70 g/l.

Combined Utilization of Agro-Industrial Wastewaters for Non-lignocellulosic Second-Generation Bioethanol Production

Bioethanol is one of the most important renewable fuels, and its production from biomass is a potential substitute for fossil fuels. Second-generation technologies cover a wide range of biomass resources, from agriculture to forestry and waste materials. Although lignocellulosic residues represent an attractive feedstock for ethanol production, their processing is not economical due to problems arising from the recalcitrant nature of the biomass and the need for pretreatment. The main purpose of this work was to evaluate the feasibility of the direct use of three agro-industrial wastes as low-cost feedstock for ethanol production: wastewaters of the sugar-sweetened beverage industry as carbon source, purges of fermentation tanks of the brewery industry as inoculum and corn steep water from the corn starch processing industry as nitrogen source. Fermentations were performed in batch mode under anaerobic conditions, and the concentrations of sugar, biomass and ethanol were monitored over time. The process was optimized using surface-response methodology. Spent brewer’s yeast and corn steep water supplementation at ratios of 12.4 and 8.4% v/v, respectively, were optimal for ethanol production. In these conditions, the sugar available in the soft-drink wastewater was completely depleted in less than 8 h, with an average ethanol yield of 0.45 gethanol/gsugar. The process developed could become an alternative bioprocess for production of non-lignocellulosic bioethanol.

Enzymatic Cascades for Efficient Biotransformation of Racemic Lactate Derived from Corn Steep Water

The corn starch industry produces a large amount of corn steep water, leading to high organic waste load. Lactate could be separated from corn steep water at a low cost, which supports the value-added utilization of corn steep water. However, the racemic characteristic of lactate from corn steep water restricts the development of this promising process. In this study, using d-lactate oxidase (d-LOX) from Gluconobacter oxydans, l-lactate oxidase (l-LOX) from Pediococcus sp., pyruvate decarboxylase from Zymomonas mobilis, and catalase from bovine liver, we synthesized an in vitro enzymatic system, including different enzymatic cascades, for the production of valuable platform chemicals from lactate separated from the corn steep water. Pyruvate was produced as an important intermediate and further converted into C2 (acetaldehyde) and C4 (acetoin) platform chemicals at high yields using optimized concentrations of pyruvate decarboxylase. The in vitro enzymatic system not only provides a novel technology platf...

Effects of corn steep water pretreatment on the rheological and microstructural properties of Ga-kenkey

The rheological and textural characteristics of Ga-kenkey are critical for consumer acceptability of the product. This work studied the effects of corn steep water pretreatment with potassium metabisulfite on the rheological properties of Ga-kenkey. The pasting properties of corn dough obtained from corn that was soaked in water treated with and without potassium metabisulfite were determined using the Brabender viscoamylograph. The viscoelastic properties of Ga-kenkey obtained from the sulfited and nonsulfited steeped corn were determined using the TAXT2i Texture Analyzer. There was no detectable residual sulfur dioxide in Ga-kenkey obtained from metabisulfite treated corn. Metabisulfite treatment of steep water did not significantly change the pasting temperature of corn dough (80.15–80.40 °C). However, viscosities of the pastes increased tremendously for dough obtained from corn that was steeped in metabisulfite treated water. In particular, while viscosity at 50-Hold for dough obtained from metabisulfite treated corn was 191BU, it was 140BU for dough obtained from nonmetabisulfite treated corn. The stress relaxation parameters indicated that Ga-kenkey obtained from corn that was steeped in metabisulfite treated water exhibited more pronounced elastic behavior (equilibrium modulus, Ee = 0.695 kPa) and were stiffer than that obtained from corn that was steeped in water without metabisulfite treatment (equilibrium modulus, Ee = 0.399 kPa). SEM showed that Ga-kenkey obtained from both soaking treatments had some amounts of native starch, but Ga-kenkey obtained from sulfited steep water showed a more compact microstructure with more extensive starch transformations than that obtained from nonsulfited steep water. Practical applications Kenkey is a staple food in Ghana, and its processing and sale provide employment to many people. The operations in this cottage industry need to be standardized and eventually industrialized. Consequently, the effects of key unit operations on product quality characteristics need to be rationalized and improved. In the traditional kenkey process, the corn steep water is typically discarded without further treatment. However, disposing large quantities of corn steep water without pretreatment will eventually raise environmental problems because of the foul smell. Steeping corn in dilute potassium metabisulfite will retard the growth of putrefactive organisms and prevent foul odor development in the steep water, but may affect the textural characteristics of Ga-Kenkey.

Preparation of Media for Growth and Isolation of Lactic Acid Bacteria by Using the Starch-Industry by- Products

By- products of corn starch industry were used to prepare media for propagation the lactic acid bacteria as a natural auxotroph. The by- products used were the corn steep water (S) and gluten extract (G) after a proper treatment to get them ready for media preparation. The results showed that it was possible to replace the peptone and meat extract by gluten extract in MRS medium. The growth was approximately similar to that obtained in standard MRS media. Corn steep water (S) was used as well and the growth enhanced by including Tween – 80 at 1% level. The later media named MZ, which was superior for growing standard and local strains and starters. The MZ medium modified by adding acetate and glacial acetic acid similarly to Rogosa media and was very efficient selection property for selecting and growing of lactobacilli only. There was no difference in the starter activities grown in MRS or MZ liquid media used to coagulate sterile whole milk and the developed acidity was at similar extent.