A cost-saving, safe, and highly efficient natural mediator for laccase application on aflatoxin detoxification.

Laccase mediators possess advantage of oxidizing substrates with high redox potentials, such as aflatoxin B1 (AFB1). High costs of chemically synthesized mediators limit laccase industrial application. In this study, thin stillage extract (TSE), a byproduct of corn-based ethanol fermentation was investigated as the potential natural mediator of laccases. Ferulic acid, p-coumaric acid, and vanillic acid were identified as the predominant phenolic compounds of TSE. With the assistance of 0.05 mM TSE, AFB1 degradation activity of novel laccase Glac1 increased by 17 times. The promoting efficiency of TSE was similar to ferulic acid, but superior to vanillic acid and p-coumaric acid, with 1.2- and 1.3-fold increases, respectively. After Glac1-TSE treatment, two oxidation products were identified. Ames test showed AFB1 degradation products lost mutagenicity. Meanwhile, TSE also showed 1.3-3.0 times promoting effect on laccase degradation activity in cereal flours. Collectively, a safe and highly efficient natural mediator was obtained for aflatoxin detoxification.

An overview of vinasse pollution in aquatic ecosystems in Brazil.

We review the negative impacts of vinasse, a byproduct of alcohol distillation, on Brazil's freshwater ecosystems. We found a total of 37 pollution events between the years 1935 and 2023, with this number almost certainly an underestimate due to underreporting and/or unassessed events. Pollution by vinasse occurred both through accidents (e.g., tank failure) and deliberately (i.e., opening of floodgates), although in many cases the causes remain undetermined. All pollution events caused fish kills, with some records reporting negative effects on other organisms as well (i.e., crustaceans and reptiles). Pollution by vinasse, and associated negative effects, was reported for 11 states, with a notable number of cases in São Paulo. Most cases of vinasse pollution and negative impacts on biodiversity were recorded in rivers, followed by streams and reservoirs. Some of the affected river systems harbour threatened freshwater fishes. Hydrological connectivity means that pollution could have propagated along watercourses. Given these consequences of vinasse pollution on biodiversity, ecosystem functioning and services, we recommend a number of remedial actions.

Sugarcane vinasse provokes acute and chronic responses and bioaccumulation of metals in benthic macroinvertebrates.

Brazil is a major producer of sugarcane bioethanol, which has raised concerns about its environmental impact. The industrial process for obtaining ethanol generates a by-product with a high pollution potential called vinasse. If vinasse reaches watercourses, it may affect the biological communities, such as the aquatic macroinvertebrates, which include species sensitive to environmental contamination. Thus, this study evaluated the ecotoxicological effects of sugarcane vinasse on tropical benthic macroinvertebrates (Allonais inaequalis, Chironomus sancticaroli, Strandesia trispinosa, and Hyalella meinerti). The study was divided into three phases. First, acute toxicity tests were carried out with the four species. The species A. inaequalis (average LC50 = 0.460% confidence interval, CI 0.380-0.540%) was more sensitive to vinasse than C. sancticaroli (LC50 0.721%, CI 0.565-0.878%), H. meinerti (EC50 0.781%, CI 0.637-0.925%), and S. trispinosa (EC50 1.283%, CI 1.045-1.522%). In the second phase, the consequences of chronic exposure to vinasse were assessed in the two more sensitive species. Impairments in reproduction and population growth rates for A. inaequalis and on the development, metamorphosis, and body growth of C. sancticaroli larvae occurred. Finally, the bioaccumulation of metals after chronic exposure was determined in the third phase. Vinasse provoked decreases in the body residue of the essential metals Zn and Mn and the accumulation of Cd, Pb, and Cr with the potential for biomagnification throughout the food webs. Low concentrations of vinasse (below 1%) provoked lethal and sublethal effects on benthic organisms, with several cascade effects on aquatic environments, given the ecological importance of this group in freshwater and terrestrial ecosystems.

Evaluation of corn steep liquor as fermentation media for recombinant Lactococcus lactis producing antifreeze proteins.

BACKGROUND: Corn processing byproducts corn steep liquor (CSL), and thin stillage were evaluated as growth media for recombinant Lactococcus lactis modified to produce antifreeze proteins (AFPs) that could have important food and non-food applications. The AFP III sequence from ocean pout was cloned into a shuttle vector to make an expression vector that facilitated the production of recombinant AFP III in Lactococcus lactis. Light CSL from yellow dent corn and thin stillage from the industrial corn bioethanol process were optimized as fermentation media with a combination of the following additives and trace elements: disodium-ß-glycerophosphate (DG), tryptone (T), ascorbic acid (AA), iron (Fe), zinc (Zn), and magnesium (Mg). The growth of wild-type and recombinant Lactococcus lactis strains were compared over a 72 h period in 96-well plates and 250 mL shake flasks. RESULTS: The corn coproducts media consisting of 50% (v/v) light steep in water supplemented with DG-5 g L-1 , T-5 g L-1 , AA-0.5 g L-1 , and Zn-4 ppm resulted in best growth and was considered as the best-optimized media. The addition of additives and trace elements better supported the growth of both wild-type and recombinant Lactococcus lactis strains compared to control media without any additives. Respective fermentation supernatants were frozen to -20 °C, and the time to supercool and freeze was compared. A distinct supercooling effect was observed for the supernatants from recombinant strains thus, extending the time and temperature of supercooling and freezing. The maximum time of supercooling extended was 17.55 ± 4.45 min for thin stillage followed by M17 media (17.25 ± 4.45 min), Kent Corporation CSL (10.80 ± 2.12 min), and yellow dent CSL (6.9 ± 0.85 min) when fermented with recombinant Lactococcus lactis strains. CONCLUSION: The supplemented corn coproduct-based media enhanced the growth of both wild-type and recombinant Lactococcus lactis strains. These optimized media can replace or supplement more expensive media (e.g. M17), potentially reducing cost. The fermentation supernatants exhibited longer times to supercool, and freeze compared to control supernatants, indicating potential use as antifreeze compounds in frozen food and non-food applications. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Concept for the valorization of cereal processing waste: Recovery of phenolic acids by using waste-derived tetrahydrofurfuryl alcohol and biochar.

Valorization of agro-food waste by converting it into a renewable resource plays a crucial role in a bio-based circular economy. Therefore, this study was designed to evaluate the suitability of distillery stillage (DS), which comes from alcohol production from cereals, for producing value-added products that can be used synergistically. The main objective was to investigate the usefulness of two substances for the recovery of phenolic acids, which have antioxidant activity, from the liquid fraction of DS: namely, tetrahydrofurfuryl alcohol (THFA) as a solvent and biochar as an adsorbent, both produced from the solid fraction of cereal processing waste. The effect of THFA concentration (80 and 100%) on phenolic acid yield in ultrasound-assisted extraction was studied. The solubilization predictions of phenolic compounds by the Hansen solubility parameters were in accordance with the experimental results: the yield of phenolic acids in the extracts was highest (3.76 µg g-1 dry mass) with 80% THFA. Among the extracted phenolic acids, hydroxycinnamic acids predominated over hydroxybenzoic acids, which may affect the bioactive properties of the extracts and their future applications for industrial purposes. Phenolic acids from the extracts were adsorbed on 17-170 g biochar L-1 and desorbed into water at 40-60 °C. The phenolic acid recovery was highest (∼92%) when the biochar dose was 85 g L-1 and when desorption was performed at 50 °C. After adsorption/desorption, ∼95% of the antioxidant activity of the phenolic acids in the extracts was maintained. As biochar has a smaller specific surface area than commercial powdered activated carbon (PAC), the biochar dose should be about 5 times higher than an equivalent PAC dose for adsorption efficiency above 90%.

Resistance evaluation of Canna indica, Cyperus papyrus, Iris sibirica, and Typha latifolia to phytotoxic characteristics of diluted tequila vinasses in wetland microcosms.

Tequila vinasse has a high contaminating capacity due to its physicochemical characteristics. Efficient and low-cost alternative treatments are required to reduce and control the environmental impacts caused by raw vinasse discharges, mainly from micro and small factories. One option is wetland technologies in which vegetation plays an important role in the proper functioning of the system; thus, the species to be used must be properly selected based on their resistance and tolerance to the toxic effects of vinasse. Therefore, this study aims to evaluate the resistance of four macrophyte species to tequila vinasse in wetland microcosms that is, Canna indica, Cyperus papyrus, Iris sibirica, and Typha latifolia which were exposed to 5, 7, 10, 12, and 15% of vinasse diluted with domestic wastewater. The control parameters (relative content, evapotranspiration, pH, electrical conductivity, and apparent color) showed that the plants in general developed stress symptoms. However, statistical analysis revealed a significant difference (p < 0.05) between plant species and vinasse treatments, further evidencing that I. sibirica is the species with the greatest potential to be used as emergent vegetation in treatment wetlands for the purification of tequila vinasse.

The novelty of this study lies in the fact that different species of macrophytes have been evaluated to find those with the capacity to resist the physicochemical characteristics of tequila vinasses; corroborating that there are more appropriate species than others. I. sibirica stood out mainly based on its better physiological response to the Relative Chlorophyll Content, which is the most important parameter for the evaluation of plant health. In this way, the results of this study will allow the evaluation of different types of constructed wetlands for the treatment of tequila vinasse. The knowledge generated is useful for treating other distillery stillages around the world with wetland technology.

Engineering Shewanella oneidensis to efficiently harvest electricity power by co-utilizing glucose and lactate in thin stillage of liquor industry.

Thin stillage, rich in glucose and lactate, can seriously pollute water resources when directly discharged into the natural environment. Microbial fuel cells (MFC), as a green and sustainable technology, could utilize exoelectrogens to break down organics in wastewater and harvest electricity. Nevertheless, Shewanella oneidensis MR-1, cannot utilize thin stillage for efficient power generation. Here, to enable S. oneidensis to co-utilize glucose and lactate from thin stillage, an engineered S. oneidensis G7∆RSL1 was first created by constructing glucose metabolism pathway, promoting glucose and lactate co-utilization, and enhancing biofilm formation. Then, to enhance biofilm conductivity, we constructed a 3D self-assembled G7∆RSL1-rGO/CNT biohybrid with maximum power density of 560.4 mW m-2 and 373.7 mW m-2 in artificial and actual thin stillage, respectively, the highest among the reported genetically engineered S. oneidensis with thin stillage as carbon source. This study provides a new strategy to facilitate practical applications of MFC in wastewater remediation and efficient power recovery.

Process options for the recovery of a pentosan-enriched fraction from wheat-based bioethanol thin stillage.

AIM: Stillage, the main residue from cereal-based bioethanol production, offers a great potential for the recovery of pentosan-type carbohydrates. Therefore, potential process options for the recovery of pentosans from bioethanol thin stillage are investigated and their basic feasibility is demonstrated on a laboratory scale. FINDINGS: The main result of this work is the development of a three-stage process for pentosan recovery, including solid-liquid separation, pentosan solubilisation and purification. The pentosan content of the thin stillage used here was determined to be about 14% related to dry matter (DM). By means of solid-liquid separation, these pentosans accumulate in the liquid phase (up to 80%), while the remainder (about 20%) is found in the solid phase. Solubilisation of these insoluble pentosans was achieved by using either a hydrothermal, an alkaline or an enzymatic treatment. Here, the results indicate a maximum solubilisation yield of 90% with a hydrothermal treatment using liquid hot water at 180 °C. Ultrafiltration and precipitation are investigated for purification. The most promising process option in this study is solid-liquid separation followed by ultrafiltration. In this case, the total pentosan yield is assessed to be about 48% (based on thin stillage) with a final pentosan concentration of about 30%DM.

Cellulosic Ethanol Production Using Waste Wheat Stillage after Microwave-Assisted Hydrotropic Pretreatment.

One of the key elements influencing the efficiency of cellulosic ethanol production is the effective pretreatment of lignocellulosic biomass. The aim of the study was to evaluate the effect of microwave-assisted pretreatment of wheat stillage in the presence of sodium cumene sulphonate (NaCS) hydrotrope used for the production of second-generation bioethanol. As a result of microwave pretreatment, the composition of the wheat stillage biomass changed significantly when compared with the raw material used, before treatment. Microwave-assisted pretreatment with NaCS effectively reduced the lignin content and hemicellulose, making cellulose the dominant component of biomass, which accounted for 42.91 ± 0.10%. In post pretreatment, changes in biomass composition were also visible on FTIR spectra. The peaks of functional groups and bonds characteristic of lignins (C-O vibration in the syringyl ring, asymmetric bending in CH3, and aromatic skeleton C-C stretching) decreased. The pretreatment of the analyzed lignocellulosic raw material with NaCS resulted in the complete conversion of glucose to ethanol after 48 h of the process, with yield (in relation to the theoretical one) of above 91%. The highest observed concentration of ethanol, 23.57 ± 0.10 g/L, indicated the high effectiveness of the method used for the pretreatment of wheat stillage that did not require additional nutrient supplementation.

Volumetric Scale-Up of a Packed-Bed Ion-Exchange System to Extract Phytate from Thin Stillage.

Phytate is the main form of phosphorus in corn ethanol coproducts and poses digestion issues in monogastric-animal feed. Extracting phytate as a commodity chemical will bring extra revenue to the corn ethanol industry and reduces potential phosphorus pollution from livestock waste management. We assessed a simplified scale-up approach of an ion-exchange separation system applied to extract phytate from thin stillage using volumetric parameters and simplifications of the van Deemter model. Thin stillage is one of the main byproducts generated on dry-grind corn-to-ethanol plants and accounts for the liquid portion of the bottom product generated in the ethanol distillation process. Thin stillage is rich in dissolved phytate, which served as the basis for an ion-exchange extraction system developed with a scalability factor of 50. Under the evaluated conditions, similar breakthrough profiles were obtained when similar Péclet and Stanton numbers were maintained for the scales studied, demonstrating that a simple and straightforward scale-up can be attained if special attention is given to maintaining both parameters as the basis of calculations of the plate numbers of ion-exchange columns.

Development of Resource-Saving Biotechnology for the Production of a Feed Additive from Distiller's Wastes with Probiotic Properties.

The trend towards an increase in ethanol production on a global scale and the tightening of restrictive measures regarding the disposal of by-products from production increases the relevance of research in finding ways to process them. This study aimed to assess the effectiveness of a feed additive containing dried stillage fermented with pre-immobilized cultures of Lactobacillus pontis 67, Lb. casei 22, Lb. paracasei 104 when finishing steers. The dose of inoculum (3.0%) of a liquid probiotic drug based on the consortium Lb. pontis 67, Lb. casei 22, Lb. paracasei 104 was determined, cultivation time 24-30 hours at a bacterial titer of 10-10 CFU/ml, and the characteristics of fermented stillage and a feed additive based on it were established. Studies were conducted to assess the effectiveness of finishing when using fermented wheat stillage on the qualitative characteristics of the carcass of 13-month-old Kazakh white-headed steers on finishing. The studies were conducted in 2 groups: control and experimental (13% fermented stillage). The experimental group showed higher indicators of average daily gain (Р<0.05), carcass weight, and slaughter yield (P<0.05). According to the results of the conducted research, it can be concluded that the replacement of protein components of compound feed with stillage in an amount of 10% and a probiotic drug based on the bacteria Lb. pontis 67, Lb. casei 22, Lb. paracasei 104 in an amount of 3.0% contributes to an increase in weight gain when finishing steers by 9.1±0.3 kg, average daily gain by 417±2.0 g, and slaughter yield by 3.1±0.2% compared with the control group (P<0.05).

Diverse Profile of Fermentation Byproducts From Thin Stillage.

The economy of biorefineries is influenced not only by biofuel production from carbohydrates but also by the production of valuable compounds from largely underutilized industrial residues. Currently, the demand for many chemicals that could be made in a biorefinery, such as succinic acid (SA), medium-chain fatty acids (MCFAs), and lactic acid (LA), is fulfilled using petroleum, palm oil, or pure carbohydrates as raw materials, respectively. Thin stillage (TS), the residual liquid material following distillation of ethanol, is an underutilized coproduct from the starch biofuel industry. This carbon-rich material has the potential for chemical upgrading by microorganisms. Here, we explored the formation of different fermentation products by microbial communities grown on TS using different bioreactor conditions. At the baseline operational condition (6-day retention time, pH 5.5, 35°C), we observed a mixture of MCFAs as the principal fermentation products. Operation of a bioreactor with a 1-day retention time induced an increase in SA production, and a temperature increase to 55°C resulted in the accumulation of lactic and propionic acids. In addition, a reactor operated with a 1-day retention time at 55°C conditions resulted in LA accumulation as the main fermentation product. The prominent members of the microbial community in each reactor were assessed by 16S rRNA gene amplicon sequencing and phylogenetic analysis. Under all operating conditions, members of the Lactobacillaceae family within Firmicutes and the Acetobacteraceae family within Proteobacteria were ubiquitous. Members of the Prevotellaceae family within Bacteroidetes and Lachnospiraceae family within the Clostridiales order of Firmicutes were mostly abundant at 35°C and not abundant in the microbial communities of the TS reactors incubated at 55°C. The ability to adjust bioreactor operating conditions to select for microbial communities with different fermentation product profiles offers new strategies to explore and compare potentially valuable fermentation products from TS and allows industries the flexibility to adapt and switch chemical production based on market prices and demands.

Treatment of thin stillage by Aspergillus oryzae and its effect on alcoholic fermentation in syrup liquid.

The microbial degradation of thin stillage for environment-friendly treatment has been studied extensively in recent years, and useful compounds in the treated-thin stillage are expected to be utilized in the subsequent fermentation. In this study, an Aspergillus oryzae H18, suitable for growing in thin stillage, was isolated from soil and served to degrade the organic matter in thin stillage, with the increase in pH (from 3·75 to 4·8) and decrease in chemical oxygen demand (COD, 81·3% removal rate). The effect of thin stillage as backset water after degradation of the strain H18 on alcohol production in syrup liquid was investigated. Compared with zero addition of thin stillage, the alcohol yield in mixed syrup liquid increased by 8·6% when the concentration of treated-thin stillage was 20%. After the addition of nutrients at proper concentration (0·5% urea, 1% molasses, 0·25% NaCl, 0·2% NaH2 PO4 , 0·3% MgSO4 and 0·25% CaCl2 ) in thin stillage, the alcohol yield in yeast fermentation was increased by 32·7% when mixed syrup liquid (with 40% thin stillage treated by H18) was employed, in comparison to control group without thin stillage addition. Meanwhile, the fermentation time was shortened, and alcohol production rate was enhanced.

Microwave-assisted hydrotropic pretreatment as a new and highly efficient way to cellulosic ethanol production from maize distillery stillage.

Aim of the study was to assess the suitability of the combined use of microwave radiation and sodium cumene sulfonate under optimized process conditions for the preparation of maize stillage biomass as a raw material for the production of cellulosic ethanol. The key parameter guaranteeing a high level of lignin removal from biomass (ca. 44%) was concentration of hydrotrope. Even at high biomass concentration (16% w/v) and a cellulase enzyme dose of about 4 filter-paper units/g, maize stillage biomass subjected to microwave-assisted hydrotropic pretreatment was highly susceptible to enzymatic degradation, which resulted in 80% hydrolysis yield. It is possible to obtain a fermentation medium with a very high glucose concentration (up to 80 g/L), without fermentation inhibitors and, as a consequence, to reach a very high level of sugar conversion to ethanol (concentration above 40 g/L), even as much as 95% of theoretical yield. Microwave hydrotropic treatment with sodium cumene sulfonate is a very effective way to prepare waste maize stillage biomass for the production of cellulosic ethanol. The degradation of the lignocellulose structure by the simultaneous use of microwaves and hydrotropes ensured a high degree of conversion of structural polysaccharides to bioethanol. The method provides a high level of enzymatic degradation of cellulose, leading to a medium with high content of released sugars suitable for bioconversion, which is in line with assumptions of the second-generation ethanol production technology. KEY POINTS: • Microwave-assisted hydrotropic pretreatment is a new way to cellulosic ethanol production. • Microwave-assisted hydrotropic delignification removes 44% of lignin from biomass. • No fermentation inhibitors are obtained after microwave-assisted hydrotropic pretreatment. • High ethanol concentration (above 40 g/L) and fermentation yield (95% of theoretical yield) from biomass after microwave-assisted hydrotropic pretreatment.

High-solid digestion from cellulosic ethanol stillage with activated sludge of simultaneous propionate degradation and methanogenesis.

High solid anaerobic digestion (HSAD) was an emerging bioconversion technology which had the advantages of small digester, less digestate and low heating energy. A one-stage anaerobic system in CSTR by inoculating activated sludge of simultaneous propionate degradation and methanogenesis was proposed to improve the high-solid digestion performance and to stabilize the reaction process. Semi-continuous mode was successfully used to perform HSAD from cellulosic ethanol whole stillage at an initial substrate loading of 15.4% (w/w) dry matter content with different OLRs from 1.5 to 5.0 gVS·L-1 d-1 at an HRT of 30 days. The average methane yield during whole digestion reached 349.9 mL⋅gVS-1 with a total VS removal rate of 61.3%. The acclimation mechanism of multifunctional activated sludge was also explored by analyzing the functional property, physiological activity and microbial community structure. The results indicated the feasibility and efficiency of multifunctional activated sludge in a semi-continuous high-solid stirred tank reactor system.

Microbial lipid production from banana straw hydrolysate and ethanol stillage.

In this study, the feasibility of banana straw (BS) hydrolysate as carbon source and reutilizing the pretreated liquor (PL) of BS in the Rhodosporidium toruloides fermentation was explored for the first time. When BS hydrolysate was used as the carbon source, total biomass concentration, lipid concentration, and lipid content under optimal conditions reached 15.52 g/L, 5.83 g/L, and 37.56% (w/w), respectively, which was similar to the results of pure sugar control. After detoxification, 50% PL can be returned to enzymatic hydrolysis and fermentation, and total biomass concentration, lipid concentration, and lipid content can reach 15.14 g/L, 5.59 g/L, and 36.91% (w/w). Then, ethanol stillage (ES) was used as the nitrogen source. The NaCl and glycerol of ES could promote lipid accumulation, reaching 7.52 g/L under optimized conditions. Finally, microbial lipid production from BS hydrolysate and ES without any additional nutrients was investigated, and the maximum total biomass concentration, lipid concentration, and lipid content were 13.55 g/L, 4.88 g/L, and 36.01% (w/w), respectively. Besides, the main compositions of microbial lipid produced were C16 and C18, and the biodiesel production from the microbial lipid could meet Chinese and US standard through theoretical numerical calculation.

Efficient anaerobic digestion of a mild wet air pretreated molasses ethanol distillery stillage: A comparative approach.

The effect of a mild, wet air pretreatment and the subsequent anaerobic digestion (AD) was examined on the recovery of a complex and toxic molasses ethanol distillery stillage. The biogas yield and organics removal due to pretreatment were compared with the raw stillage AD. The application of a scoria support in this industrial residue AD process stability was also assessed. Consequently, a statistically significant cumulative specific methane recovery difference (p-value = 0.000) with an almost complete biological oxygen demand (BOD) removal and a significant chemical oxygen demand (COD) reduction, which were 100% and 92% respectively were achieved. Additionally, the biogas recovery rate was hastened due to pretreatment. The application of scoria, whose property has been instrumentally inspected, has helped stabilize the pH in the AD systems. In a comparative approach, this study suggests the energy benefit and an ecofriendly discharge of stillage by the ethanol industry towards sustainability.

Corn Bioethanol Side Streams: A Potential Sustainable Source of Fat-Soluble Bioactive Molecules for High-Value Applications.

This paper reports data from a characterization study conducted on the unsaponifiable lipid fraction of dry-grind corn bioethanol side streams. Phytosterols, squalene, tocopherols, tocotrienols, and carotenoids were quantified by High Performance Liquid Chromatography with Diode-Array Detector (HPLC-DAD) and Liquid Chromatography-tandem Mass Spectrometry (LC-MS/MS) in different lots of post-fermentation corn oil and thin stillage collected from a bioethanol plant over a time-span of one year. Fat-soluble bioactives were present at high levels in corn oil, with a prevalence of plant sterols over tocols and squalene. Beta-sitosterol and sitostanol accounted altogether for more than 60% of total sterols. The carotenoid profile was that typical of corn, with lutein and zeaxanthin as the prevalent molecules. The unsaponifiable lipid fraction profile of thin stillage was qualitatively similar to that of post-fermentation corn oil but, in quantitative terms, the amounts of valuable biomolecules were much lower because of the very high dilution of this side stream. Results indicate that post-fermentation corn oil is a promising and sustainable source of health-promoting bioactive molecules. The concomitant presence of a variegate complex of bioactive molecules with high antioxidant potentialities and their potential multifaceted market applications as functional ingredients for food, nutraceutical, and cosmeceutical formulations, make the perspective of their recovery a promising strategy to create new bio-based value chains and maximize the sustainability of corn dry-grind bioethanol biorefineries.

Towards a Valorization of Corn Bioethanol Side Streams: Chemical Characterization of Post Fermentation Corn Oil and Thin Stillage.

First-generation biofuel biorefineries may be a starting point for the development of new value chains, as their by-products and side streams retain nutrients and valuable molecules that may be recovered and valorized for high-value applications. This study provides a chemical characterization of post-fermentation corn oil and thin stillage, side streams of dry-grind corn bioethanol production, in view of their valorization. An overall long-term study was conducted on the two co-products collected over 1 year from a bioethanol plant. Water content, acid value, sedimentation, mineral composition, and fatty acid profiles were analyzed on post-fermentation corn oil. Results highlighted that its acid value was high (19.72-24.29 mg KOH/g), indicating high levels of free fatty acids, but stable over the year due to standardized operating conditions. The fatty acid profile was that typical of corn oil, with a prevalence of linoleic (54-59% of total fatty acids) over oleic (23-27%) and palmitic (12-17%) acids. Macronutrients, fatty acid, and mineral profiles were investigated in thin stillage. Results revealed the acidic pH (4.05-4.68) and high dilution (90-93% water) of this side stream. The dry mass was composed of fats (19-30%), proteins (8.8-12.8%), ash (8.7-9.5%), and fiber (7.3-9.8%). The concomitant presence of a variegate complex of molecules of nutritional interest in corn bioethanol co-products, with several potential high-value market applications, make the perspective of their recovery a promising strategy to create new cross-sector interconnections according to circular economy principles.