The Future of Coproducts From Corn Processing

Insights into Grain Milling and Fractionation Practices for Improved Food Sustainability with Emphasis on Wheat and Peas

Cereal grains and pulses are staple foods worldwide, being the primary supply of energy, protein, and fiber in human diets. The current practice of milling and fractionation yields large quantities of byproducts and waste, which are largely downgraded and end up as animal feeds or fertilizers. This adversely affects food security and the environment, and definitely implies an urgent need for a sustainable grain processing system to rectify the current issues, particularly the management of waste and excessive use of water and energy. The current review intends to discuss the limitations and flaws of the existing practice of grain milling and fractionation, along with potential solutions to make it more sustainable, with an emphasis on wheat and peas as common fractionation crops. This review discusses a proposed sustainable grain processing system for the fractionation of wheat or peas into flour, protein, starch, and value-added components. The proposed system is a hybrid model that combines dry and wet fractionation processes in conjunction with the implementation of three principles, namely, integration, recycling, and upcycling, to improve component separation efficiency and value addition and minimize grain milling waste. The three principles are critical in making grain processing more efficient in terms of the management of waste and resources. Overall, this review provides potential solutions for how to make the grain processing system more sustainable.

Macroscopic modeling of the growth and substrate consumption of wild type and genetically modified Pichia pastoris

Pichia pastoris is a popular yeast platform to generate several industrially relevant products which have applications in a wide range of sectors. The complexities in the processes due to the addition of a foreign gene are not widely explored. Since these complexities can be dependent on the strain characteristics, promoter, and type of protein produced, it is vital to investigate the growth and substrate consumption patterns of the host to facilitate customized process optimization. In this study, the growth rates of P. pastoris GS115 wild type (WT) and genetically modified (GM) strains grown on glycerol and methanol in batch cultivation mode were estimated and the model providing the best representation of the true growth kinetics based on substrate consumption was identified. It was observed that the growth of P. pastoris exhibits Haldane kinetics on glycerol rather than the most commonly used Monod kinetics due to the inability of the latter to describe growth inhibition at high concentrations of glycerol. Whereas, the cardinal parameter model, a newly proposed model for this application, was found to be the best fitting to describe the growth of P. pastoris on methanol due to its ability to describe methanol toxicity. Interestingly, the findings from this study concluded that in both substrates, the genetically engineered strain exhibited a higher growth rate compared to the WT strain. Such an observation has not been established yet in other published works, indicating an opportunity to further optimize the carbon source feeding strategies when the host is grown in fed-batch mode.

Buffering Capacity Comparison of Tris Phosphate Carbonate and Buffered Peptone Water Salmonella Pre-Enrichments for Manufactured Feed and Feed Ingredients

Various culture-based methods to detect Salmonella in animal feed have been developed due to the impact of this bacterium on public and animal health. For this project, tris phosphate carbonate (TPC) and buffered peptone water (BPW) buffering capacities were compared as pre-enrichment mediums for the detection of Salmonella in feed ingredients. A total of 269 samples were collected from 6 feed mills and mixed with the pre-enrichments; pH was measured before and after a 24 h incubation. Differences were observed when comparing pH values by sample type; DDGS and poultry by-product meal presented lower initial pH values for TPC and BPW compared to the other samples. For both TPC and BPW, meat and bone meal presented higher final pH values, while soybean meal and peanut meal had lower final pH values. Furthermore, for BPW, post cooling, pellet loadout, and wheat middlings reported lower final pH values. Additionally, most feed ingredients presented significant differences in pH change after 24 h of incubation, except DDGS. From meat and bone meal samples, four Salmonella isolates were recovered and identified: three using BPW and one using TPC. TPC provided greater buffer capacity towards neutral pH compared to BPW, but BPW was more effective at recovering Salmonella.

Machine-learning-facilitated prediction of heavy metal contamination in distiller's dried grains with solubles

Excessive heavy metal contamination often occurs in feed due to natural or anthropogenic activity, leading to poisoning and other health problems in animals. In this study, a visible/near-infrared hyperspectral imaging system (Vis/NIR HIS) was used to reveal the different characteristics of spectral reflectance of Distillers Dried Grains with Solubles (DDGS) doped with various heavy metals and to effectively predict metal concentrations. Two types of sample treatment were used, namely tablet and bulk. Three quantitative analysis models were constructed based on the full wavelength, and through comparison the support vector regression (SVR) model was found to show the best performance. As typical heavy metal contaminants, copper (Cu) and zinc (Zn) were used for modeling and prediction. The prediction set accuracy of the tablet samples doped with Cu and Zn was 94.9% and 86.2%, respectively. In addition, a novel characteristic wavelength selection model based on SVR (SVR-CWS) was proposed to filter characteristic wavelengths, which improved the detection performance. The regression accuracy of the SVR model on the prediction set of tableted samples with different Cu and Zn concentrations was 94.7% and 85.9%, respectively. The accuracy of bulk samples with different Cu and Zn concentrations was 81.3% and 80.3%, respectively, which indicated that the detection method can reduce the pretreatment steps and verify its practicability. The overall results suggested the potential of Vis/NIR-HIS in the detection of feed safety and quality.

Sustainable Isolation of Bioactive Compounds and Proteins from Plant-Based Food (and Byproducts)

Plant-based food produces significantly less greenhouse gases, and due to its wealth of bioactive components and/or plant-based protein, it becomes an alternative in a sustainable food system. However, the processing and production of products from plant sources creates byproducts, which can be waste or a source of useful substances that can be reused. The waste produced during the production and processing of food is essentially nutrient- and energy-rich, and it is recognized as an excellent source of secondary raw materials that could be repurposed in the process of manufacturing and preparing food, or as feed for livestock. This review offers an overview of the sources and techniques of the sustainable isolation of bioactive substances and proteins from various sources that might represent waste in the preparation or production of food of plant origin. The aim is to uncover novel approaches to use waste and byproducts from the process of making food to provide this waste food an additional benefit, not forgetting the expectations of the end user, the consumer. For the successful isolation of bioactive ingredients and proteins from food of plant origin, it is crucial to develop more eco-friendly and efficient extraction techniques with a low CO2 footprint while considering the economic aspects.

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-β-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.

Turning Food Protein Waste into Sustainable Technologies

For each kilogram of food protein wasted, between 15 and 750 kg of CO₂ end up in the atmosphere. With this alarming carbon footprint, food protein waste not only contributes to climate change but also significantly impacts other environmental boundaries, such as nitrogen and phosphorus cycles, global freshwater use, change in land composition, chemical pollution, and biodiversity loss. This contrasts sharply with both the high nutritional value of proteins, as well as their unique chemical and physical versatility, which enable their use in new materials and innovative technologies. In this review, we discuss how food protein waste can be efficiently valorized not only by reintroduction into the food chain supply but also as a template for the development of sustainable technologies by allowing it to exit the food-value chain, thus alleviating some of the most urgent global challenges. We showcase three technologies of immediate significance and environmental impact: biodegradable plastics, water purification, and renewable energy. We discuss, by carefully reviewing the current state of the art, how proteins extracted from food waste can be valorized into key players to facilitate these technologies. We furthermore support analysis of the extant literature by original life cycle assessment (LCA) examples run ad hoc on both plant and animal waste proteins in the context of the technologies considered, and against realistic benchmarks, to quantitatively demonstrate their efficacy and potential. We finally conclude the review with an outlook on how such a comprehensive management of food protein waste is anticipated to transform its carbon footprint from positive to negative and, more generally, have a favorable impact on several other important planetary boundaries.

Techno-Economic Evaluation of Phosphorous Recovery in Soybean Biodiesel Process

The over-enrichment of phosphorus in waste streams can lead to eutrophication and oxygen limitations for aquatic life. To understand the release of phosphorus from a soybean processing facility, it is imperative to track the flow of phosphorus in different streams during the processing of soybeans. The objective of the study is to develop process simulation models to study the flow of phosphorus in the soy-biodiesel process and evaluate strategies to mitigate phosphorus release by recovering phosphorous from soapstock and wastewater. Since most of the P is found in soybean meal, the processing of which releases phosphorus, a third case of lecithin recovery was also studied to reduce the amount of phosphorous in soybean meal. It was observed that phosphorus can be economically recovered from the soapstock, as well as the wastewater stream, with an estimated operating cost of USD 1.65 and 3.62 per kg of phosphorous recovered, respectively. The phosphorus recovered from both streams can be potentially applied as fertilizer to more than 13,000 acres of corn or 96,000 acres of soybean, respectively. The lecithin recovery case was found to have the highest revenue, and it led to a 54% reduction in phosphorous during soybean meal processing.

Coprocessing Corn Germ Meal for Oil Recovery and Ethanol Production: A Process Model for Lipid-Producing Energy Crops

Efforts to engineer high-productivity crops to accumulate oils in their vegetative tissue present the possibility of expanding biodiesel production. However, processing the new crops for lipid recovery and ethanol production from cell wall saccharides is challenging and expensive. In a previous study using corn germ meal as a model substrate, we reported that liquid hot water (LHW) pretreatment enriched the lipid concentration by 2.2 to 4.2 fold. This study investigated combining oil recovery with ethanol production by extracting oil following LHW and simultaneous saccharification and co-fermentation (SSCF) of the biomass. Corn germ meal was again used to model the oil-bearing energy crops. Pretreated germ meal hydrolysate or solids (160 and 180 °C for 10 min) were fermented, and lipids were extracted from both the spent fermentation whole broth and fermentation solids, which were recovered by centrifugation and convective drying. Lipid contents in spent fermentation solids increased 3.7 to 5.7 fold compared to the beginning germ meal. The highest lipid yield achieved after fermentation was 36.0 mg lipid g−1 raw biomass; the maximum relative amount of triacylglycerol (TAG) was 50.9% of extracted oil. Although the fermentation step increased the lipid concentration of the recovered solids, it did not improve the lipid yields of pretreated biomass and detrimentally affected oil compositions by increasing the relative concentrations of free fatty acids.

Value-Added Products from Ethanol Fermentation—A Review

Global demand for renewable and sustainable energy is increasing, and one of the most common biofuels is ethanol. Most ethanol is produced by Saccharomyces cerevisiae (yeast) fermentation of either crops rich in sucrose (e.g., sugar cane and sugar beet) or starch-rich crops (e.g., corn and starchy grains). Ethanol produced from these sources is termed a first-generation biofuel. Yeast fermentation can yield a range of additional valuable co-products that accumulate during primary fermentation (e.g., protein concentrates, water soluble metabolites, fusel alcohols, and industrial enzymes). Distillers’ solubles is a liquid co-product that can be used in animal feed or as a resource for recovery of valuable materials. In some processes it is preferred that this fraction is modified by a second fermentation with another fermentation organism (e.g., lactic acid bacteria). Such two stage fermentations can produce valuable compounds, such as 1,3-propanediol, organic acids, and bacteriocins. The use of lactic acid bacteria can also lead to the aggregation of stillage proteins and enable protein aggregation into concentrates. Once concentrated, the protein has utility as a high-protein feed ingredient. After separation of protein concentrates the remaining solution is a potential source of several known small molecules. The purpose of this review is to provide policy makers, bioethanol producers, and researchers insight into additional added-value products that can be recovered from ethanol beers. Novel products may be isolated during or after distillation. The ability to isolate and purify these compounds can provide substantial additional revenue for biofuel manufacturers through the development of marketable co-products.

A review on the use of dried distiller’s grains with solubles (DDGS) in aquaculture feeds

Distiller’s dried grains with soluble (DDGS) to replace fishmeal (FM) or other plant protein sources and its effects on an aquatic animal’s growth performance and health system is rarely discussed. In recent times FM use in aquafeed has been a problem for the aquaculture industry because of the depletion of fish resources in the ocean and the high cost of FM. For that reason, researchers are focusing on reducing the cost of aquafeed production by lowering the inclusion of FM in aquafeed. One of the low-cost alternative protein sources to replace FM is DDGS. The present review discusses the compilation of available literature review and other works on the use of DDGS to replace FM in aquafeed and how it improves the growth performance, immune health system, and disease resistance in an aquatic animal. It focuses on the production of DDGS, the nutritional composition of DDGS, the chemical and physical characteristics of DDGS, and the effects of the DDGS inclusion in aquafeed on the aquatic animal. Apart from improving the growth performance of the aquatic animal when included in aquafeed, it also helps improve the immune health system of the animal. It also helps boost the immune system of the aquatic animal to fight diseases and increase disease resistance when included in aquafeed. Furthermore, DDGS also contains some constituents like carotenoids that help improve the meat quality of the animal when included in aquafeed. The current review also discusses the management and use of technology to improve the aquaculture industry, educate farmers on reducing diseases during the culturing periods, and increase productivity and profit in a friendly environment.

Effects of physical preparation of diets and inclusion rate of modified wet distillers grains with solubles on production and rumen measurements of lactating dairy cows

Our objective was to determine if methods for preparing total mixed ration [TMR; horizontal paddle mixer with knives (PK) vs. vertical auger (VA) mixer] would alter the physical form of the TMR and affect utilization of diets with increasing amounts of modified wet distillers grains with solubles (MWDGS). Holstein cows (n = 24 with 12 ruminally cannulated; 144 d in milk ± 31 d at start) were used in a split-plot design with mixer type as the whole plot and MWDGS concentrations as subplots in a replicated 3 × 3 Latin square arrangement with 35-d periods. Inclusion rates of MWDGS were 10, 20, and 30% of dietary dry matter, primarily replacing corn, soybean meal, soyhulls, and whole cottonseed. Feed dry matter intake (DMI) was less for PK (23.8 kg/d) than for VA (25.7 kg/d), but was unaffected by MWDGS concentration. Milk production did not differ by concentration of MWDGS or by interaction of MWDGS × mixer. Milk fat percentage declined with increasing MWDGS but the interaction between mixer and MWDGS showed that decreases were larger with VA mixing. Cows fed the diet containing 30% MWDGS mixed with PK averaged 3.45% (1.24 kg/d) milk fat, whereas cows fed the same diet mixed with VA averaged 2.81% (1.10 kg/d) fat. Concentrations of trans-10,cis-12 C18:2 in milk fat likely explain the differences observed in milk fat yield; the concentration of trans-10,cis-12 C18:2 increased as MWDGS was increased and the MWDGS × mixer interaction showed that VA had greater concentrations. Greater mean particle size and increased variation in particle size with VA may partially explain differences in milk fat via increased sorting that allowed for an altered rumen environment and favored alternative biohydrogenation pathways. Feed conversion efficiency (FCE; energy-corrected milk/DMI) decreased linearly as MWDGS increased, but FCE tended to be maintained when higher MWDGS diets were mixed using PK rather than VA. Ruminal pH and ammonia concentration decreased linearly as MWDGS increased. The PK mixer resulted in greater FCE when higher amounts of MWDGS were fed, primarily because milk fat content and yield were not as depressed and DMI was lower at similar milk yields.

Recoveries of Oil and Hydrolyzed Sugars from Corn Germ Meal by Hydrothermal Pretreatment: A Model Feedstock for Lipid-Producing Energy Crops

Vegetable oil is extracted from oil rich seeds, such as soybeans. Genetic engineering of green plants to accumulate oil in vegetative tissue is a future source of oil that promises increased land productivity and the use of marginal lands. However, the low concentration of lipids in current engineered plant biomass samples makes the oil extraction process challenging and expensive. In this study, liquid hot water (LHW) pretreatment was investigated to enhance oil recovery from the solids and increase enzymatic hydrolysis efficiency of such feedstocks. Corn germ meal was chosen as a model feedstock representing lipid-producing energy crops. Germ meal was pretreated at 160 and 180 °C for 10 and 15 min at 20% w/w solids loading. Enzymatic hydrolysis on the pretreated solid was performed. After pretreatment, the oil concentration increased by 2.2 to 4.2 fold. The most severe pretreatment condition of LHW, at 180 °C for 15 min, gave the maximum oil concentration (9.7%, w/w), the highest triacylglycerol (TAG) content of the extracted oil (71.6%), and the highest conversions of glucose and xylose (99.0% and 32.8%, respectively). This study demonstrates that the optimal pretreatment condition for corn germ meal is 180 °C LHW for 15 min. Pretreatment improves lipids recovery from oil bearing biomass with little or no effect on the lipid profile.

Effects of supplemental xylanase on health of the small intestine in nursery pigs fed diets with corn distillers' dried grains with solubles

Forty pigs [10.7 ± 1.2 kg initial body weight (BW) at 6 wk of age] were used in a 21-d study to evaluate the effects of supplemental xylanase (Hostazym X 100, Huvepharma, Inc., Peachtree City, GA) in nursery diets on digesta viscosity, nutrient digestibility, health of the small intestine, and growth performance when supplemented with corn distillers' dried grains with solubles (DDGS). Pigs were individually housed and randomly allotted to four treatments in a 2 × 2 factorial arrangement (n = 20/factor, 0% or 30% DDGS and 0 or 1,500 endo-pentosanase unit/kg xylanase as two factors) based on sex and initial BW. Feed intake and BW were recorded weekly. On day 15 of the study, TiO2 in diets (0.3%) was used as an indigestible marker to calculate apparent ileal digestibility (AID). Plasma samples were collected on day 19 to measure tumor necrosis factor-alpha (TNF-α), malondialdehyde, and peptide YY. On day 21, all pigs were euthanized to collect tissues from duodenum, jejunum, and colon to measure morphology, TNF-α, and malondialdehyde concentrations. Distal jejunal digesta were collected to measure viscosity. Ileum digesta were collected to measure AID of nutrients. During the entire period, supplemental xylanase increased (P < 0.05) average daily gain (ADG; 616 to 660 g/d) of nursery pigs, whereas DDGS (0 or 30%) did not affect ADG. On week 3, average daily feed intake (ADFI) was increased (P < 0.05) when fed DDGS (1,141 to 1,267 g/d) and there was an interaction (P < 0.05) between two factors indicating that supplemental xylanase decreased ADFI when DDGS was used in a diet. Use of DDGS increased (P < 0.05) viscosity [1.86 to 2.38 centipoise (cP)], whereas supplemental xylanase reduced (P < 0.05) viscosity (2.27 to 1.96 cP) of jejunal digesta. The AID of dry matter (DM) and gross energy (GE) were improved (P < 0.05) by supplemental xylanase. Plasma TNF-α was decreased (P < 0.05, 108.5 to 69.9 pg/mL) by supplemental xylanase. Use of DDGS reduced (P < 0.05) villus height:crypt depth ratio (1.46 to 1.27), whereas supplemental xylanase increased (P < 0.05) the crypt depth (360 to 404 µm) in duodenum. In conclusion, feeding a diet with 30% DDGS to nursery pigs for 3 wk had no negative effect on growth performance, whereas reduced AID of DM and GE, increased TNF-α level in colon tissue, and reduced the ratio of villus height to crypt depth. Dietary supplementation of xylanase reduced digesta viscosity improving AID of nutrients, reduced inflammatory response, and altered intestinal morphology, collectively improving ADG of nursery pigs regardless of the use of DDGS in a diet.

Phosphorus fractionation and protein content control chemical phosphorus removal from corn biorefinery streams

The economic viability of corn biorefineries depends heavily on the sale of coproducts as animal feeds, but elevated phosphorus (P) contents can exacerbate manure management issues. Phosphorus removal from light steep water and thin stillage, two concentrated in-process aqueous streams at wet milling and dry-grind corn biorefineries, could simultaneously generate concentrated fertilizer and low-P animal feeds, but little is known regarding how differences in stream composition affect removal. To address this data gap, we show that the solubility of P in light steep filtrate (LSF) and thin stillage filtrate (TSF) exhibits distinct sensitivity to calcium (Ca) and base addition due to differences in P fractionation and protein abundance. In LSF, P was primarily organic, and near-complete removal of P (96%) was observed at pH 8 and a Ca/total P (TP) ratio of 2. In TSF, TP removal was lower (81%), and there was more equal distribution of organic and orthophosphate, indicating that the Ca requirements of inorganic P precipitation were a limiting factor. The C/H/N ratio, elemental characterization, and crude protein analysis of the precipitated solids indicated that coprecipitation of amorphous solids containing Ca, Mg, and K with soluble proteins facilitated removal of P, particularly in LSF. Although the removal mechanisms and solubility limits differed, these results highlighted the magnitude (40-70 mM) and efficacy (80-96%) of P recovery from two biorefinery streams.

Meat quality traits and feeding distillers grains to cattle: a review

Livestock management and meat production involve a series of steps that affect meat quality. Animal genetics, nutrition and diets, slaughter procedures and meat-preservation conditions are some of the parameters that should be controlled to maintain meat quality. In regard to animal nutrition and diets, novel ingredients are increasingly used, distillers grains (DG) being an example. DG are obtained as a co-product from bioethanol production and comprise the fat, protein, fibre and micronutrient portion of the grains. Many papers have studied the inclusion of DG in finishing diets and their effect on growth performance and meat characteristics, but a review on the effects on meat quality is needed. Feeding with DG influences beef colour; nevertheless, a relationship between the level of inclusion and colour development has not been established yet. In addition, feeding DG-inclusion diets sometimes increases meat discoloration during retail display. Also, the composition of fatty acids is modified since total polyunsaturated fatty acid content in meat increases with the inclusion of DG in finishing diets. This increment in polyunsaturated fatty acid content is likely to contribute to lipid oxidation processes and might be related to meat discoloration due to myoglobin oxidation. However, meat tenderness has not been modified in most of the cases. This review focused on recent studies on DG inclusion, animal performance and meat quality. Key points that need further research are also identified and discussed.

Toward a Regional Phosphorus (Re)cycle in the US Midwest

Redirecting anthropogenic waste phosphorus (P) flows from receiving water bodies to high P demand agricultural fields requires a resource management approach that integrates biogeochemistry, agronomy, engineering, and economics. In the US Midwest, agricultural reuse of P recovered from spatially colocated waste streams stands to reduce point-source P discharges, meet agricultural P needs, and-depending on the speciation of recovered P-mitigate P losses from agriculture. However, the speciation of P recovered from waste streams via its chemical transformation-referred to here as recovered P (rP) differs markedly based on waste stream composition and recovery method, which can further interact with soil and crop characteristics of agricultural sinks. The solubility of rP presents key tensions between engineered P recovery and agronomic reuse because it defines both the ability to remove organic and inorganic P from aqueous streams and the crop availability of rP. The potential of rP generation and composition differs greatly among animal, municipal, and grain milling waste streams due to the aqueous speciation of P and presence of coprecipitants. Two example rP forms, phytin and struvite, engage in distinct biogeochemical processes on addition to soils that ultimately influence crop uptake and potential losses of rP. These processes also influence the fate of nitrogen (N) embodied in rP. The economics of rP generation and reuse will determine if and which rP are produced. Matching rP species to appropriate agricultural systems is critical to develop sustainable and financially viable regional exchanges of rP from wastewater treatment to agricultural end users.

Bioethanol production from waste lignocelluloses: A review on microbial degradation potential

Tremendous explosion of population has led to about 200% increment of total energy consumptions in last twenty-five years. Apart from conventional fossil fuel as limited energy source, alternative non-conventional sources are being explored worldwide to cater the energy requirement. Lignocellulosic biomass conversion for biofuel production is an important alternative energy source due to its abundance in nature and creating less harmful impacts on the environment in comparison to the coal or petroleum-based sources. However, lignocellulose biopolymer, the building block of plants, is a recalcitrant substance and difficult to break into desirable products. Commonly used chemical and physical methods for pretreating the substrate are having several limitations. Whereas, utilizing microbial potential to hydrolyse the biomass is an interesting area of research. Because of the complexity of substrate, several enzymes are required that can act synergistically to hydrolyse the biopolymer producing components like bioethanol or other energy substances. Exploring a range of microorganisms, like bacteria, fungi, yeast etc. that utilizes lignocelluloses for their energy through enzymatic breaking down the biomass, is one of the options. Scientists are working upon designing organisms through genetic engineering tools to integrate desired enzymes into a single organism (like bacterial cell). Studies on designer cellulosomes and bacteria consortia development relating consolidated bioprocessing are exciting to overcome the issue of appropriate lignocellulose digestions. This review encompasses up to date information on recent developments for effective microbial degradation processes of lignocelluloses for improved utilization to produce biofuel (bioethanol in particular) from the most plentiful substances of our planet.

Impact of Fractionation Process on the Technical and Economic Viability of Corn Dry Grind Ethanol Process

Use of corn fractionation techniques in dry grind process increases the number of coproducts, enhances their quality and value, generates feedstock for cellulosic ethanol production and potentially increases profitability of the dry grind process. The aim of this study is to develop process simulation models for eight different wet and dry corn fractionation techniques recovering germ, pericarp fiber and/or endosperm fiber, and evaluate their techno-economic feasibility at the commercial scale. Ethanol yields for plants processing 1113.11 MT corn/day were 37.2 to 40 million gal for wet fractionation and 37.3 to 31.3 million gal for dry fractionation, compared to 40.2 million gal for conventional dry grind process. Capital costs were higher for wet fractionation processes ($92.85 to $97.38 million) in comparison to conventional ($83.95 million) and dry fractionation ($83.35 to $84.91 million) processes. Due to high value of coproducts, ethanol production costs in most fractionation processes ($1.29 to $1.35/gal) were lower than conventional ($1.36/gal) process. Internal rate of return for most of the wet (6.88 to 8.58%) and dry fractionation (6.45 to 7.04%) processes was higher than the conventional (6.39%) process. Wet fractionation process designed for germ and pericarp fiber recovery was most profitable among the processes.

Increasing ethanol yield through fiber conversion in corn dry grind process

Conversion of corn fiber to ethanol in the dry grind process could increase ethanol yields, reduce downstream processing costs and improve overall process profitability. This work investigates the in-situ conversion of corn fiber into ethanol (cellulase addition during simultaneous saccharification and fermentation) during dry grind process. Addition of 30 FPU/g fiber cellulase resulted in 4.6% increase in ethanol yield compared to the conventional process. Use of excess cellulase (120 FPU/g fiber) resulted in incomplete fermentation and lower ethanol yield compared to the conventional process. Multiple factors including high concentrations of ethanol and phenolic compounds were responsible for yeast stress and incomplete fermentation in excess cellulase experiments.

Ethanol Production from Corn Fiber Separated after Liquefaction in the Dry Grind Process

Conversion of corn fiber to ethanol in the dry grind process can increase ethanol yields, improve coproduct quality and contribute to process sustainability. This work investigates the use of two physio-chemical pretreatments on corn fiber and effect of cellulase enzyme dosage to improve ethanol yields. Fiber separated after liquefaction of corn was pretreated using (I) hot water pretreatment (160 °C for 5, 10 or 20 min) and (II) wet disk milling and converted to ethanol. The conversion efficiencies of hot water pretreated fiber were higher than untreated fiber, with highest increase in conversion (10.4%) achieved for 5 min residence time at 160 °C. Disk milling was not effective in increasing conversion compared to other treatments. Hydrolysis and fermentation of untreated fiber with excess cellulase enzymes resulted in 33.3% higher conversion compared to untreated fiber.

Concentrations of minerals in pig feed ingredients commonly used in China

Mineral concentrations were determined in 13 different feed ingredients commonly used in swine diets. Ingredients included corn and 4 corn co-products: corn gluten feed, corn gluten meal, corn germ meal, and corn distillers dried grains with solubles (DDGS). Wheat, wheat bran, and wheat shorts were also included, and 5 oilseed meals including soybean meal, rapeseed meal, sunflower meal, cottonseed meal, and peanut meal were used as well. Corn grain contained 88.7% dry matter (DM) and 0.46% K (DM basis). Greater concentrations of DM, ash, Ca, P, nonphytate P, Cu, Fe, Mn, and Zn were observed in corn gluten feed, corn DDGS, and corn germ meal compared with corn grain (P < 0.05). In general, minerals in corn DDGS were approximately three times greater than in corn grain and about 90% of the total P in corn DDGS was in the nonphytate bound form. Corn gluten meal had the least concentrations (P < 0.05) of most minerals, but the greatest (P < 0.05) concentrations of Fe (373.55 mg/kg, DM basis), Cu (11.88 mg/kg, DM basis), and Se (0.92 mg/kg, DM basis). On a DM-basis, concentrations of DM, Ca, P, phytate bound P, and Fe in wheat grain were 88.2%, 0.10%, 0.34%, 0.16%, and 53.48 mg/kg, respectively. Wheat bran contained more (P < 0.05) K, Mg, Cl, Fe, Zn, and Mn compared with wheat and wheat shorts. On a DM-basis, 2.72% K was observed in soybean meal, which was more (P < 0.05) than in the other oilseed meals. However, rapeseed meal had the greatest (P < 0.05) concentration of ash (9.37%), Ca (1.01%), P (1.05%), and Fe (526.49 mg/kg) among the oilseed meals, but only 16.2% of the total P in rapeseed meal was non-phytate P. In contrast, more than 50% of the P in soybean meal and peanut meal was non-phytate P. The least (P < 0.05) concentration of Cu (6.73 mg/kg, DM basis) was observed in rapeseed meal and the greatest (P < 0.05) concentration (32.75 mg/kg) was analyzed in sunflower meal. Concentrations of most minerals in soybean meal, rapeseed meal, sunflower meal, cottonseed meal, and peanut meal varied considerably compared with published values. In conclusion, the concentration of minerals in 13 commonly used feed ingredients were analyzed and results indicated considerable variation among and within feed ingredients for most minerals, which for some minerals may be a result of differences in minerals in the soil in which the ingredients were grown, but processing likely also contributes to differences among ingredients.

Phytate extraction from coproducts of the dry-grind corn ethanol process

Distiller's dried grains with solubles (DDGSs), the major coproduct of dry-grind ethanol production, are being increasingly used in the global market as animal feeds for both energy and protein supplement.

Evaluation of Selected Nutrients and Contaminants in Distillers Grains from Ethanol Production in Texas

This article contains the results of the evaluation of distillers grain (DG) coproducts from different ethanol plants around the United States and supplemented in animal diets in Texas, based on samples analyzed from 2008 to 2014. The samples were assessed for concentration, occurrence, and prevalence of selected nutrients and contaminants. Protein and sulfur contents of DG were largely different between maize and sorghum coproducts, as well as wet distillers grain with solubles (WDGS) and dried distillers grain with solubles (DDGS), indicating a significant effect of grain feedstock and dry grind process stream on DG composition and quality. Salmonella was isolated in 4 DDGS samples of a total of 157 DG samples, a percentage (2.5%) that is lower than the percentage of Salmonella -positive samples found in other feed samples analyzed during the same period. A small amount of virginiamycin residue was found in 24 maize DDGS, 1 maize WDGS, and 2 sorghum DDGS samples of 242 samples in total. One sorghum DDGS sample of 168 DG samples was contaminated with animal protein prohibited for use in ruminant feed and was channeled to poultry feed. The concentrations of aflatoxin and fumonisin DG coproducts averaged 3.4 μg/kg and 0.7 mg/kg, respectively. Among contaminated maize DG samples, five DDGS samples for aflatoxin contained a higher concentration than the U.S. Food and Drug Administration (FDA) minimum action level of 20 μg/kg for use in animal feed, whereas no sample for fumonisin was found above the action level of 5 mg/kg. The study provides the most current results involving DG coproducts and associated hazards that will assist development of food safety plans required by the FDA in their September 2015 rule titled "Current Good Manufacturing Practice Hazard Analysis and Risk Based Preventive Controls for Food for Animals."

Dry-grind processing using amylase corn and superior yeast to reduce the exogenous enzyme requirements in bioethanol production

BACKGROUND

Conventional corn dry-grind ethanol production process requires exogenous alpha and glucoamylases enzymes to breakdown starch into glucose, which is fermented to ethanol by yeast. This study evaluates the potential use of new genetically engineered corn and yeast, which can eliminate or minimize the use of these external enzymes, improve the economics and process efficiencies, and simplify the process. An approach of in situ ethanol removal during fermentation was also investigated for its potential to improve the efficiency of high-solid fermentation, which can significantly reduce the downstream ethanol and co-product recovery cost.

RESULTS

The fermentation of amylase corn (producing endogenous α-amylase) using conventional yeast and no addition of exogenous α-amylase resulted in ethanol concentration of 4.1 % higher compared to control treatment (conventional corn using exogenous α-amylase). Conventional corn processed with exogenous α-amylase and superior yeast (producing glucoamylase or GA) with no exogenous glucoamylase addition resulted in ethanol concentration similar to control treatment (conventional yeast with exogenous glucoamylase addition). Combination of amylase corn and superior yeast required only 25 % of recommended glucoamylase dose to complete fermentation and achieve ethanol concentration and yield similar to control treatment (conventional corn with exogenous α-amylase, conventional yeast with exogenous glucoamylase). Use of superior yeast with 50 % GA addition resulted in similar increases in yield for conventional or amylase corn of approximately 7 % compared to that of control treatment. Combination of amylase corn, superior yeast, and in situ ethanol removal resulted in a process that allowed complete fermentation of 40 % slurry solids with only 50 % of exogenous GA enzyme requirements and 64.6 % higher ethanol yield compared to that of conventional process.

CONCLUSIONS

Use of amylase corn and superior yeast in the dry-grind processing industry can reduce the total external enzyme usage by more than 80 %, and combining their use with in situ removal of ethanol during fermentation allows efficient high-solid fermentation.

Microfiltration of vinasse: sustainable strategy to improve its nutritive potential

The purpose of this article was to evaluate and establish microfiltration (MF) operating conditions for vinasse (ethanol industries wastewater also known as stillage, slop, distillery effluent or dunder) concentration aiming to improve the use of its nutritive potential. The operating conditions influence permeate flux that has been evaluated by monitoring the flow rate profile during the operation on bench scale in different conditions (feed pH, aeration condition and recovery rate). From the results found, the process scale up was then effected. The bench scale findings showed that the vinasse microfiltration under air flow of 0.5 m(3).h(-1) between membrane fibers, with no pH adjustment, and recovery rate of 93% produced two flows, one of permeate that may be used to wash the sugarcane during the ethanol production processing, and the other of concentrate that contains a high organic compounds and nutrients concentration. This concentrate has additional potentiality of being used as organic compound supplement in contaminated soil bioremediation, and as a supplier of microbial biomass or substrate for biosurfactant production.

The bio refinery; producing feed and fuel from grain

It is both possible and practicable to produce feed and fuel from grain. Using the value of grain to produce renewable energy for transport, while using the remaining protein content of the grain as a valuable protein source for livestock and for fish, can be seen as a complimentary and optimal use of all the grain constituents. Consideration must be given to maximise the value of the yeast components, as substantial yeast is generated during the fermentation of the grain starch to produce ethanol. Yeast is a nutritionally rich feed ingredient, with potential for use both as feed protein and as a feed supplement with possible immunity and gut health enhancing properties. Bioprocessing, with the consequent economies of scale, is a process whereby the value of grain can be optimised in a way that is traditional, natural and sustainable for primarily producing protein and oil for feed with a co-product ethanol as a renewable fuel.

Improved glycerol utilization by a triacylglycerol-producing Rhodococcus opacus strain for renewable fuels

BACKGROUND

Glycerol generated during renewable fuel production processes is potentially an attractive substrate for the production of value-added materials by fermentation. An engineered strain MITXM-61 of the oleaginous bacterium Rhodococcus opacus produces large amounts of intracellular triacylglycerols (TAGs) for lipid-based biofuels on high concentrations of glucose and xylose. However, on glycerol medium, MITXM-61 does not produce TAGs and grows poorly. The aim of the present work was to construct a TAG-producing R. opacus strain capable of high-cell-density cultivation at high glycerol concentrations.

RESULTS

An adaptive evolution strategy was applied to improve the conversion of glycerol to TAGs in R. opacus MITXM-61. An evolved strain, MITGM-173, grown on a defined medium with 16 g L(-1) glycerol, produced 2.3 g L(-1) of TAGs, corresponding to 40.4% of the cell dry weight (CDW) and 0.144 g g(-1) of TAG yield per glycerol consumed. MITGM-173 was able to grow on high concentrations (greater than 150 g L(-1)) of glycerol. Cultivated in a medium containing an initial concentration of 20 g L(-1) glycerol, 40 g L(-1) glucose, and 40 g L(-1) xylose, MITGM-173 was capable of simultaneously consuming the mixed substrates and yielding 13.6 g L(-1) of TAGs, representing 51.2% of the CDM. In addition, when 20 g L(-1) glycerol was pulse-loaded into the culture with 40 g L(-1) glucose and 40 g L(-1) xylose at the stationary growth phase, MITGM-173 produced 14.3 g L(-1) of TAGs corresponding to 51.1% of the CDW although residual glycerol in the culture was observed. The addition of 20 g L(-1) glycerol in the glucose/xylose mix resulted in a TAG yield per glycerol consumed of 0.170 g g(-1) on the initial addition and 0.279 g g(-1) on the pulse addition of glycerol.

CONCLUSION

We have generated a TAG-producing R. opacus MITGM-173 strain that shows significantly improved glycerol utilization in comparison to the parental strain. The present study demonstrates that the evolved R. opacus strain shows significant promise for developing a cost-effective bioprocess to generate advanced renewable fuels from mixed sugar feedstocks supplemented with glycerol.

Microbial production of short chain diols

Short chain diols (propanediols, butanediols, pentanediols) have been widely used in bulk and fine chemical industries as fuels, solvents, polymer monomers and pharmaceutical precursors. The chemical production of short chain diols from fossil resources has been developed and optimized for decades. Consideration of the exhausting fossil resources and the increasing environment issues, the bio-based process to produce short chain diols is attracting interests. Currently, a variety of biotechnologies have been developed for the microbial production of the short chain diols from renewable feed-stocks. In order to efficiently produce bio-diols, the techniques like metabolically engineering the production strains, optimization of the fermentation processes, and integration of a reasonable downstream recovery processes have been thoroughly investigated. In this review, we summarized the recent development in the whole process of bio-diols production including substrate, microorganism, metabolic pathway, fermentation process and downstream process.

Effects of conjugated linoleic acid or betaine on the growth performance and fatty acid composition in backfat and belly fat of finishing pigs fed dried distillers grains with solubles

The objectives of this study were to determine the effects of conjugated linoleic acid (CLA) or betaine on the growth performance, carcass characteristics and fatty acid composition in backfat and belly fat of pigs fed distillers dried grains with solubles (DDGS). Thirty-two (60±2 kg) crossbred barrows (Duroc×Landrace×Yorkshine) were assigned to one of four diets randomly: (1) the control diet containing no corn DDGS (control group); (2) the diet containing 30% corn DDGS (DDGS-fed group); (3) the diet containing 30% corn DDGS and 10 g/kg CLA (CLA-fed group); (4) the diet containing 30% corn DDGS and 1 g/kg BET (BET-fed group). The pigs fed DDGS showed that the percentages of C18:2, polyunsaturated fatty acid (PUFA) and iodine value (IV) increased, while C18:1, saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) decreased. Pigs fed the DDGS+CLA or DDGS+betaine diets showed the increased percentage of SFA, and the decreased percentage of C18:2, PUFA and IV. In conclusion, results confirmed that the diets containing 30% DDGS had no detrimental effects on growth performance, but increased the percentage of PUFA and IV and decreased the percentage of SFA and MUFA in the backfat and belly fat. However, supplementation with CLA or BET can part reverse these effects on carcass fat in finishing pigs.

Molecular spectroscopic investigation on fractionation-induced changes on biomacromolecule of co-products from bioethanol processing to explore protein metabolism in ruminants

Fractionation processing is an efficient technology which is capable to redesign/redevelop a new food or feed product with a specified chemical and nutrient profile. This processing technique was able to produce four different fractions (called "A", "B", "C", "D" fractions/treatments) with different nutrient profile form a co-product of bioethanol processing [wheat dried distillers grains with soluble (DDGS)]. To date, there is no study on the effect of fractionation processing on inherent molecular structure of different fractions and how the processing-induced structural change affect the metabolic characteristics of protein and nutrient availability. The objectives of this experiment were to: (1) investigate the effect of fractionation processing on changes of protein functional groups (amide I, amide II, and their ratio) and molecular structure (modeled α-helix, β-sheet, and their ratio), and (2) study the relationship between the fractionation processing-induced changes of protein molecular structure and nutrients availability as well as the metabolic characteristics of protein. The hypothesis of this study was that the fractionation processing changes the molecular structure and such changes affect the metabolic characteristics of protein. The protein molecular structure spectral profile of the fractions A, B, C and D were identified by Fourier-transform infrared attenuated total reflection spectroscopy (FT/IR-ATR). The results showed that the fractionation processing significantly affected the protein molecular spectral profiles. The differences in amide I to amide II peak area and height ratios were strongly significant (P<0.01) among the treatment fractions, ranging from 4.98 to 6.33 and 3.28 to 4.00, respectively. The difference in the modeled protein α-helix to β-sheet ratio was also strongly significant (P<0.01) among the treatment fractions. Multivariate molecular spectral analysis with cluster (CLA) and principal component analyses (PCA) showed that there are no clear distinguished clusters and ellipses among the fractions (A, B, C and D) in the protein amide I and II region ca. 1726-1485 cm(-1). The correlation study showed that the modeled α-helix to β-sheet ratio tended to have a negative correlation with truly absorbed rumen undegraded protein (ARUP(DVE): r=-0.944, P=0.056<0.10) and total truly absorbed protein in the small intestine (DVE: r=-0.946, P=0.054<0.10), but there was no correlation between the α-helix to β-sheet ratio and the degraded protein balance (DPB(OEB): P=0.267<0.10). In conclusion, the fractionation processing changed the molecular structural spectral profiles in terms of amide I to II ratio and α-helix to β-sheet ratio. These changes negatively affected the metabolic characteristics of protein and true protein supply. These results indicated that spectral features of different fractions could be used as a potential tool to predict true protein nutritive value.

Establishment and assessment of a novel cleaner production process of corn grain fuel ethanol

An integrated corn ethanol-methane fermentation system was proposed to solve the problem of stillage handling, where thin stillage was treated by anaerobic digestion and then reused to make mash for the following ethanol fermentation. This system was evaluated at laboratory and pilot scale. Anaerobic digestion of thin stillage ran steadily with total chemical oxygen demand removal efficiency of 98% at laboratory scale and 97% at pilot scale. Ethanol production was not influenced by recycling anaerobic digestion effluent at laboratory and pilot scale. Compared with dried distillers' grains with solubles produced in conventional process, dried distillers' grains in the proposed system exhibited higher quality because of increased protein concentration and decreased salts concentration. Energetic assessment indicated that application of this novel process enhanced the net energy balance ratio from 1.26 (conventional process) to 1.76. In conclusion, the proposed system possessed technical advantage over the conventional process for corn fuel ethanol production.

Industrial symbiosis: corn ethanol fermentation, hydrothermal carbonization, and anaerobic digestion

The production of dry-grind corn ethanol results in the generation of intermediate products, thin and whole stillage, which require energy-intensive downstream processing for conversion into commercial animal feed products. Hydrothermal carbonization of thin and whole stillage coupled with anaerobic digestion was investigated as alternative processing methods that could benefit the industry. By substantially eliminating evaporation of water, reductions in downstream energy consumption from 65% to 73% were achieved while generating hydrochar, fatty acids, treated process water, and biogas co-products providing new opportunities for the industry. Processing whole stillage in this manner produced the four co-products, eliminated centrifugation and evaporation, and substantially reduced drying. With thin stillage, all four co-products were again produced, as well as a high quality animal feed. Anaerobic digestion of the aqueous product stream from the hydrothermal carbonization of thin stillage reduced chemical oxygen demand (COD) by more than 90% and converted 83% of the initial COD to methane. Internal use of this biogas could entirely fuel the HTC process and reduce overall natural gas usage.