Corn Pericarp Research Articles

Development of Pericarp-Based Coatings from Corn Nixtamalization Residue for Stone Fruits: Applications for Peach and Tejocote

This study investigated corn pericarp, a by-product of the nixtamalization process, in developing sustainable films for fruit coatings. These films were evaluated for their optical, structural, barrier, and mechanical properties. The results showed that the pericarp films were transparent, had heterogeneous surfaces, and exhibited favorable mechanical and barrier properties, suggesting their potential as fruit coatings. The pericarp films significantly extended shelf life when applied to peaches and tejocotes postharvest. The films slowed the maturation process, as evidenced by minimal changes in peel and mesocarp color for up to five days for tejocotes and even longer for peaches. Additionally, coated fruits showed slower rates of weight loss, firmness reduction, and decreases in titratable acidity, total soluble solids, and total sugar content compared to control samples. These findings demonstrate the potential of corn pericarp films as effective coatings for extending the shelf life of stone fruits.

Microencapsulation of highly concentrated polyphenolic compounds from purple corn pericarp by spray-drying with various biomacromolecules

Colored corn pericarp contains unusually high amounts of industrially valuable phytochemicals, such as anthocyanins, flavanols, flavonoids, and phenolic acids. Polyphenols were extracted in an aqueous solution and spray-dried to produce microencapsulates using four carrier materials, namely, maltodextrin (MD), gum arabic (GA), methylcellulose (MC), and skim milk powder (SMP) at three concentrations (1, 2, and 3 %, respectively). The encapsulates were evaluated for their polyphenolic contents using spectrophotometric techniques and HPLC analyses, and their antioxidant properties were evaluated using four different assays. The physicochemical properties of encapsulates were analyzed by measuring the zeta potential (ZP), particle size distribution, water solubility index (WSI), water absorption index (WAI), and color parameters. Structural and thermal properties were evaluated using Fourier transform infrared spectroscopy (FTIR), optical profilometry, and differential scanning calorimetry (DSC) analyses. Comparative analysis of structural characteristics, particle size distribution, zeta potential, WSI, WAI, and aw of the samples confirmed the successful formulation of encapsulates. The microencapsulates embedded with 1 % concentrations of MD, MC, GA, or SMP retained polyphenolic compounds and exhibited noteworthy antioxidant properties. The samples encapsulated with GA or MD (1 %) demonstrated superior physicochemical, color, and thermal properties. Comprehensive metabolomic analysis confirmed the presence of 38 phytochemicals in extracts validating the spray-drying process.

Evaluation of dry milling characteristics and polyphenolic contents of fourteen conventionally bred colored corn varieties for value-added coproducts recovery

Corn pericarp is a low value cellulosic coproduct. However, colored corn pericarp contains disproportionately higher amounts of polyphenolic compounds such as anthocyanins, flavonoids, flavonols, tannins and phenolic acids, and can be selectively utilized for their economic recovery. Due to the diverse industrial applications of these value-added phytochemicals, colored corn can supplement the lower economic value of conventional yellow dent corn. In this study, dry milling characteristics and polyphenolic contents (anthocyanins, total phenols, and condensed tannins) of fourteen conventionally bred and midwestern US grown colored varieties and their milling coproducts were ascertained and compared with a commercial purple corn. With mean large grits yield of 22.98% (db), colored varieties had a dominant softer endosperm, suitable for wet milling and dry grind industry. The mean starch content of colored varieties was lower than conventional yellow dent corn (∼9.91%, db), and the mean protein content was higher (∼1.70%, db). Although purple corn contained the highest amounts, four experimental varieties had high concentrations of polyphenols. Through HPLC analyses, a diverse mix of various anthocyanin forms, phenolic acids, and flavonoids were identified. The antioxidant potential of polyphenolic extracts from five varieties were evaluated using four different assays, and significant antioxidant activities were observed. Histological analysis was conducted on polyphenol-rich varieties, and most of the pigments were found to be concentrated in pericarp. The pericarp thickness was greatest for the variety containing the maximum polyphenolic compounds. Adapted colored corn varieties can be valorised to recover value-added polyphenolic compounds in line with the circular bioeconomic paradigm.

Sustainable Innovation: Fabrication and Characterization of Mycelium-Based Green Composites for Modern Interior Materials Using Agro-Industrial Wastes and Different Species of Fungi.

Mycelium-based bio-composites (MBCs) represent a sustainable and innovative material with high potential for contemporary applications, particularly in the field of modern interior design. This research investigates the fabrication of MBCs for modern interior materials using agro-industrial wastes (bamboo sawdust and corn pericarp) and different fungal species. The study focuses on determining physical properties, including moisture content, shrinkage, density, water absorption, volumetric swelling, thermal degradation, and mechanical properties (bending, compression, impact, and tensile strength). The results indicate variations in moisture content and shrinkage based on fungal species and substrate types, with bamboo sawdust exhibiting lower shrinkage. The obtained density values range from 212.31 to 282.09 kg/m3, comparable to traditional materials, suggesting MBCs potential in diverse fields, especially as modern interior elements. Water absorption and volumetric swelling demonstrate the influence of substrate and fungal species, although they do not significantly impact the characteristics of interior decoration materials. Thermal degradation analysis aligns with established patterns, showcasing the suitability of MBCs for various applications. Scanning electron microscope observations reveal the morphological features of MBCs, emphasizing the role of fungal mycelia in binding substrate particles. Mechanical properties exhibit variations in bending, compression, impact, and tensile strength, with MBCs demonstrating compatibility with traditional materials used in interior elements. Those produced from L. sajor-caju and G. fornicatum show especially promising characteristics in this context. Particularly noteworthy are their superior compression and impact strength, surpassing values observed in certain synthetic foams multiple times. Moreover, this study reveals the biodegradability of MBCs, reaching standards for environmentally friendly materials. A comprehensive comparison with traditional materials further supports the potential of MBCs in sustainable material. Challenges in standardization, production scalability, and market adoption are identified, emphasizing the need for ongoing research, material engineering advancements, and biotechnological innovations. These efforts aim to enhance MBC properties, promoting sustainability in modern interior applications, while also facilitating their expansion into mass production within the innovative construction materials market.

From purple corn waste (pericarp) to polyphenol-rich extract with higher bioactive contents and superior product qualities using two-step optimization techniques

The pericarp of purple corn has traditionally been thought of as being a byproduct. However, it is an excellent source of high-value polyphenols (such as anthocyanins, proanthocyanins, etc.) that could be extracted and used as nutraceuticals, cosmeceuticals, and valuable starting material for synthesizing food colorants and food additives. Hence, this study aimed to optimize the recovery of anthocyanins, phenolic acids, and condensed tannins (CT) from purple corn pericarp using a two-stage multivariate design and evaluated the phenolic profiles, antioxidants, product quality, and structural characteristics of the recovered extracts. According to Plackett-Burman design (PBD) screening, the key extraction variables identified were acetic acid concentration, extraction time, and ethanol concentration. This was followed by optimization using Box-Behnken design (BBD), facial central composite design (FCCD), and full-factorial design (FFD), and the best design was identified after comparative analysis. The models were found to be acceptable, as evidenced by the desirability values of 0.836–0.933. A comparison of the BBD, FCCD, and FFD was done, and it was found that the PBD-BBD produced a lower residual standard error (RSE) than the PBD-FCCD for most of the responses and yielded the lowest extraction time (∼8.6 h), proving that the BBD could forecast the data more accurately. To evaluate the extracts' bioactive extraction efficiency, antioxidant properties, product quality, and structural parameters, samples from a single factor (SF) experiment and BBD were compared. The BBD extract had better color properties (lower ΔE, higher a*, C, and H0) and a greater extraction yield (17.5%) than SF and was confirmed by the principal component and hierarchical cluster analysis. Although the scanning electron microscopy and the optical profilometer for BBD revealed irregular, loosely arranged granules, it had a less adverse effect on product quality and aligned with the Fourier transform infrared spectroscopy results. The BBD samples had lower levels of phenolic acids but higher levels of total phenolic content (118.86 ± 3.60 g GAE/kg), condensed tannins (231.74 ± 8.45 g EE/kg), antioxidants, cyanidin-3-glucoside (90.46 ± 4.47 mg/g), naringin (7.68 ± 0.58 mg/g), and cyanidin-chloride (49.81 ± 1.78 mg/g). This shows that BBD can effectively be used to optimize the extraction of polyphenolic compounds from purple corn pericarp using optimal extraction conditions, resulting in a higher yield of polyphenols having superior antioxidant properties and product quality in a comparatively shorter extraction time.

Novel Two-pot Microwave Extraction of Purple Corn Pericarp’s Phenolics and Evaluation of the Polyphenol-rich Extract’s Product Quality, Bioactivities, and Structural Properties

Novel Two-pot Microwave Extraction of Purple Corn Pericarp’s Phenolics and Evaluation of the Polyphenol-rich Extract’s Product Quality, Bioactivities, and Structural Properties

Sonoprocessing improves phenolics profile, antioxidant capacity, structure, and product qualities of purple corn pericarp extract

For the first time, purple corn pericarp (PCP) was converted to polyphenol-rich extract using two-pot ultrasound extraction technique. According to Plackett-Burman design (PBD), the significant extraction factors were ethanol concentration, extraction time, temperature, and ultrasonic amplitude that affected total anthocyanins (TAC), total phenolic content (TPC), and condensed tannins (CT). These parameters were further optimized using the Box-Behnken design (BBD) method for response surface methodology (RSM). The RSM showed a linear curvature for TAC and a quadratic curvature for TPC and CT with a lack of fit > 0.05. Under the optimum conditions (ethanol (50%, v/v), time (21 min), temperature (28 °C), and ultrasonic amplitude (50%)), a maximum TAC, TPC, and CT of 34.99 g cyanidin/kg, 121.26 g GAE/kg, and 260.59 of EE/kg, respectively were obtained with a desirability value 0.952. Comparing UAE to microwave extraction (MAE), it was found that although UAE had a lower extraction yield, TAC, TPC, and CT, the UAE gave a higher individual anthocyanin, flavonoid, phenolic acid profile, and antioxidant activity. The UAE took 21 min, whereas MAE took 30 min for maximum extraction. Regarding product qualities, UAE extract was superior, with a lower total color change (ΔE) and a higher chromaticity. Structural characterization using SEM showed that MAE extract had severe creases and ruptures, whereas UAE extract had less noticeable alterations and was attested by an optical profilometer. This shows that ultrasound, might be used to extract phenolics from PCP as it requires lesser time and improves phenolics, structure, and product qualities.

Effect of synchronizing the rate degradation of protein and organic matter of feed base on corn waste on fermentation characteristic and synthesis protein microbial

Synchronization of feed sources of energy and protein can produce a positive influence on microbial protein synthesis, especially in ruminants that are fed low quality feed such as corn waste. Corn waste, including corn straw and corn peri carp are widely used as beef cattle feed. The objective of this research was to determine the effect of synchronizing the rate degradation of protein and energy of feed base on corn waste on rumen fermentation characteristic and synthesis protein microbial on 24 hours in vitro condition. The three synchronization index levels in corn-based feed waste are 0.4 (low); 0.5 (moderate) and 0.6 (high) were used in this study. Characteristics of rumen fermentation observed were pH, individual volatile fatty acids (acetic acid, propionic acid and butyric acid), NH3, C02, CH4, degradation of organic matter, microbial protein production, and efficiency of microbial protein synthesis. Increasing the synchronization index level caused a significant increase (P<0.05) of NH3 (53.60 to 59.07 mg/L) and efficiency of microbial protein synthesis (14.83 to 17.87) , but high synchronization index decrease (P<0.05) the concentration of acetic acid (22.45 mM to 15.95 mM), estimated CO2 (18.69 to 15.50 mol) and CH4 (11.49 to 7.98) in rumen fluid. This result indicated that the improvement of synchronization index can improve the productivity of livestock through increase efficiency of microbial protein synthesis and it reduce global warming.

Production of extracellular enzymes by a termite‐nest‐related Bacillus siamensisYC‐9 in solid‐state fermentation on agricultural by‐products

AbstractA Bacillus siamensis YC‐9 strain was isolated from termite nest. The strain was used to produce several important industrial enzymes by utilizing different agricultural by‐products with solid‐state fermentation (SSF). It was observed that most of the substrates that were studied were strongly positively affected by alkaline treatment for the production of enzymes. The highest yields for protease, α‐amylase, and cellulase were 82.87, 42.81, and 1.54 IU g−1, achieved on alkaline‐treated corn pericarp, rice bran, and wheat bran respectively. However, untreated soybean meal was the best choice for the secretion of pectinases (66.65 IU g−1). In general, ultrasonic pretreatment was more effective than microwave treatment and it promoted the production of proteases on soybean meal, sunflower meal, and wheat bran. The findings of the present study will provide some theoretical basis for enzyme production in the future. © 2021 Society of Industrial Chemistry and John Wiley &amp; Sons Ltd.

Exposure to polyphenol-rich purple corn pericarp extract restricts fall armyworm (Spodoptera frugiperda) growth

ABSTRACT Bioactive compounds such as polyphenols in plants have been well studied for their potential insecticidal activities. These are considered as safe alternatives against chemical pesticides because of their lower persistence in environment, lower toxicity to humans and other organisms. However, they are present constitutively in lower amounts in plants and have to undergo complicated extraction methods – hampering their commercial exploitation in pest management. Using an inexpensive extraction method developed to recover polyphenol-rich liquid extract from purple corn pericarp, we recently documented that this extract has anti-feeding effects that cascade from larval to adult stages in a model herbivore tobacco hornworm (Manduca sexta). However, M. sexta does not feed on corn or any other major crops other than the species in the nightshade family (Solanaceae). In this study, we explored the same idea but using a generalist and common herbivore on corn, the fall armyworm (Spodoptera frugiperda). We found that purple corn pericarp extract inhibited the larval growth and development as well as negatively affected the pupal stages of S. frugiperda. However, unlike on M. sexta, time to complete larval life cycle was unaffected. Our findings confirm the toxicity of this extract on a generalist, economically important herbivore, but also suggest potential species-specific effects that should be explored further.

High solids all-inclusive polysaccharide hydrolysis of steam-exploded corn pericarp by periodic peristalsis

A new sequence of steam explosion (SE) with periodic peristalsis (PP) exploited to fractionate corn pericarp (CP), and its high solid cellulosic hydrolysis to increase sugar yield. In this investigation, the optimum SE-condition was 0.8 MPa/5 min., recovered around 12.62 % total sugars than untreated CP, whereas glucan and xylan digestibility reached around 97 % and 87 %, respectively. Besides that, the unground SECP conversion increased by 27.10 % glucan and 34.18 % xylan than the ground one. FE-SEM, FTIR, XRD results confirmed that SE significantly fractionated the amorphous substances that driven the increment of the crystallinity index. SE changed the functional groups without altering the lignin, and also the formation of degradations products was negligible and not detrimental to sugars conversion. An unpolluted SEPP enzymatic hydrolysis system at high solid loading (25 %) with compatible low cellulase dose (15 FPU g−1 solids) was beneficial to intensified sugars conversion.

Comparisons of catalytic efficiency during the reduction of lignocellulosic substrates between free enzyme versus enzyme bound to mobile enzyme sequestration platforms (mESP)

Plants represent a vast, renewable source of biomass. Plant biomass serves as a major substrate for sustainable biofuel production. However, to overcome the food‐versus‐fuel dilemma, effective use of plant residues for cellulosic (versus corn‐ or sugarcane‐based) ethanol must be realized. Effective deconstruction of lignocellulosic matrix and efficiently accessing and reducing cellulose to fermentable sugars (i.e., glucose) would overcome current constraints that prevent cellulosic ethanol from becoming an economically viable alternative for liquid/transportation fuel. Cellulosic feedstocks consist of cellulose (20–50%), hemicellulose (15–35%), and lignin (5–30%). In previous work, we demonstrated that the use of thermotolerant and acidotolerant engineered mobile enzyme sequestration platforms (mESP) could enhance lignocellulosic deconstruction of two acid pretreated (and alkaline pretreated) feedstocks. Specifically, acid‐pretreated wheat straw and corn pericarp were subjected to a suite of cellulases, an enzyme cocktail, under two conditions: (a) pretreated substrate plus enzymes free in solution (experimental control); and, (b) pretreated substrate plus enzymes bound to a prototype mESP. The mESP‐bound enzymes showed enhanced ability to convert complex carbohydrates to glucose (i.e., sugar reduction) when compared to the free enzyme in solution control (at equimolar enzyme concentrations). Although the mESP was known to be thermotolerant and acidotolerant, enhancement of sugar reduction efficiency was also observed with alkaline pretreated substrate. Still, these preliminary experiments only demonstrated a 2‐ to 3‐fold increase in enzymatic efficiency over controls. Indeed, with some enzyme ‘cocktails’, sugar reduction efficiency actually decreased when employing mESPs. It was suggested that steric interference between enzymes due to the close proximity of enzyme attachment points on the platform and the use of enzymes with different target points (exo‐versus endo‐) on the substrate (i.e., cellulose) may limit the magnitude of enhancement that can be achieved. After re‐engineering the mESP system to separate attachment points and strategic development of free enzyme cocktails and enzyme composition on charged mESPs, this study demonstrates that next‐generation mESPs can improve catalytic efficiency more than 3‐fold. In addition, alternative substrates have been tested (e.g., rice straw) with similar results. These results and implications for mESP technology are discussed in detail.Support or Funding InformationU.S. National Science Foundation Molecular and Cellular Biosciences (MCB) grant (Award No. 1818346; PI‐Ceballos); U.S. National Science Foundation Research Coordination Network (RCN) grant (Award No. 1624171; PI‐Ceballos)

Stability Comparisons between Natural Archaeal and Engineered Archaeal‐Bacterial Heat‐Shock Protein Subunits (α, β, and β‐cohesin) and their Oligomeric Complexes

Hyperthermophilic archaea of the Order Sulfolobales express group II chaperonins, which are commonly referred to as “heat‐shock proteins” (HSPs) due to their upregulated expression upon heat shock. There are three HSP subtypes (HSPα, HSPβ, and HSPγ). Of these, HSPα and HSPβ (a.k.a., TF55 and TF56) subunits are the most thoroughly characterized and are known to stoichiometrically assemble into double‐nonameric (18‐mer) ring structures. These HSP complexes are known to play a significant role not only in the folding of nascent proteins but also in the protection of cytosolic proteins within cells under environmental stress such as high temperature flux. In this context, there has been significant interest in re‐engineering the system as an enzyme protection platform for industrial applications. The first such prototype platform was called a “rosettasome”. The rosettasome is an 18‐mer complex composed of subunits that were fusion proteins of the archaeal HSPβ and cohesion (Type I) from Clostridium thermocellum. Enzymes endowed with a dockerin (Type I) domain bind to cohesion and consequently sequester enzymes to the HSP complex. We previously demonstrated that use of cellulase‐charged rosettasomes on acid (or alkaline) pretreated wheat straw (and corn pericarp) results in an increase in lignocellulose deconstruction and polysaccharide reduction to simple fermentable sugars (e.g., glucose). However, the two‐fold enhancement observed was not sufficient to render the system economically viable. Recently, we re‐engineered the HSP system into a next‐generation mobile enzyme sequestration platform (mESP). In this study, the relative stability of HSP subunits (natural and engineered) and HSP complexes with different subunit compositions are assessed to determine the mESP configuration that exhibits the greatest thermo‐/acido‐tolerance. Transmission electron micrographs reveal the formation of both nonameric ring and nonameric double‐ring (18‐mer) structures. Using differential scanning calorimetry (DSC), the thermodynamic stability of individual subunits as well as homomeric and heteromeric HSP complexes were examined. Results from analytical ultracentrifugation (in conjunction with DSC, TEM, and gel electrophoresis data), reveal the composition and relative stability of HSP complexes. These data show that HSPα has the highest thermal stability of the three subunits tested. In addition, these data indicate that stability of HSP complexes is significantly dependent on the conditions used in complex assembly and subunit stoichiometry. These results and implications for mESP technology are discussed in detail.Support or Funding InformationU.S. National Science Foundation Molecular and Cellular Biosciences (MCB) grant (Award No. 1818346; PI‐Ceballos); U.S. National Science Foundation EArly‐concept Grants for Exploratory Research (EAGER) grant (Award No. 0929484; PI‐Ceballos)

Purple corn (Zea mays L.) pericarp hydroalcoholic extracts obtained by conventional processes at atmospheric pressure and by processes at high pressure

Extracts of Peruvian purple corn pericarp (Zea mays L.) were obtained: (1) via supercritical fluid extraction with CO2 as solvent and EtOH-H2O (70:30, v/v) as co-solvent, (2) via pressurized liquid extraction (PLE) with EtOH-H2O (70:30, v/v) and, (3) via two conventional extraction processes, stirred vessel and Soxhlet. The extraction yields and extract compositions were compared to each other. The parameters measured were the point-to-point extraction yield, the global extraction yield and composition of extracts regarding contents of total phenolics, total flavonoids, total anthocyanins and specific anthocyanins such as cyanidin-3-glucoside, peonidin-3-glucoside and pelargonidin-3-glucoside. Antioxidant activity by DPPH and in vitro antiproliferative activity were also evaluated considering seven cancer cell lines. High yields and higher contents of phenolic compounds, accompanied by a high antioxidant activity at 50 °C, were obtained for supercritical extraction at 60 °C. Antioxidant activity showed good correlation with the content of phenolic compounds, but there was no antiproliferative activity.

Polyphenol-Rich Purple Corn Pericarp Extract Adversely Impacts Herbivore Growth and Development.

Plant secondary metabolites such as terpenes, phenolics, glycosides, and alkaloids play various functional roles including pigmentation, foliar and floral volatile synthesis, hormonal regulation, and direct and indirect defenses. Among these, phenolic compounds are commonly found in plants, but vary in the distribution of their specific compounds among plant families. Polyphenols, including anthocyanins and tannins, are widely distributed and have been well documented for their roles- primarily in plant pigmentation and also in plant defenses. However, commercialization of such compounds for use in insect pest management is severely hampered by expensive, inefficient, and time-consuming extraction protocols. Using a recently developed inexpensive and easy extraction method using the byproducts of pigmented (purple) corn processing, we examined whether the crude pericarp extract rich in polyphenols can affect the growth and development of tobacco hornworm (Manduca sexta L.) caterpillars. Our findings show that purple corn pericarp extract negatively affected M. sexta egg hatching and larval mass gain and prolonged developmental time compared to regular yellow corn extract or an artificial control diet. We also found that these effects were more severe during the early stages of caterpillar development. These results conclusively demonstrate that purple corn pericarp, an inexpensive by-product of the corn milling industry, is a valuable product with excellent potential as an insect antifeedant.

Cascading effects of polyphenol-rich purple corn pericarp extract on pupal, adult, and offspring of tobacco hornworm (Manduca sexta L.)

ABSTRACT A major bottleneck in the commercialization of plant-based pest management compounds is that the extraction methods are complex, time-consuming, and even highly expensive. Using a recently developed inexpensive extraction and quantification methodology to isolate polyphenols (including anthocyanins and condensed tannins) from purple corn pericarp, we examined their effects on Manduca sexta, a common insect herbivore. Following up on our previous work which demonstrated the negative impacts of polyphenol-rich extract on larval stages, we further examined whether there are any cascading effects on subsequent life stages (pupal and adult) including any possible transgenerational effects. Our results show that polyphenol-rich purple corn extract-fed caterpillars had significantly lower pupal mass and survival. Moreover, adult moths also had lower mass when eclosed from caterpillars reared on the extract diet. To test whether there were any transgenerational effects, we allowed male and female adults fed on purple corn extract diet and control diet to mate and lay eggs in a full factorial experiment. We found that purple corn extract-fed adult pair laid a lower number of eggs compared to other treatments. In addition, we also found that second instar M. sexta caterpillars hatched from eggs laid by any mating combination with at least one parent reared on purple corn extract gained significantly lower mass compared to caterpillars with both parents reared on the control diet. Taken together, our results show that there are cascading negative effects for feeding purple corn pericarp extract on pupal, adult, and second generation of M. sexta, reaffirming its potential application as a cost-effective and environmentally friendly pest deterrent.

Impact of hydrolysis on surface area and energy storage applications of activated carbons produced from corn fiber and soy hulls

Complete utilization of lignocellulosic biomass through the creation of value-added coproducts is one of the key strategies of the Bioenergy Technologies Office (BETO) for the cost-effective production of biofuels and biochemicals. A green approach to producing lightweight and high specific surface area (SSA) activated carbons (ACs) from sustainable biomass sources is of great interest to producers and users of energy devices such as batteries and supercapacitors. While direct conversion from biomass has been studied extensively, AC with relatively high surface areas can be produced more cost-effectively when leveraged as a co-product from a biorefinery. In this paper, we discuss the production of high specific surface area activated carbons from residual fiber (fiber remaining after extraction of C5-sugars) generated as part of a C5 biorefinery. The surface, morphological characteristics using SEM and TEM, and energy storage behavior of ACs produced using the C5 extracted residual fiber were evaluated in the present study. The ACs produced from the residual fiber delivered an order of magnitude higher surface area than the one directly from corn pericarp fiber and soy hulls. The surface area of the ACs produced from pre-hydrolysis DDG was only 10 m2/g compared to 689 m2/g for soy hulls whereas after hydrolysis these values increased significantly (DDG: 1700 m2/g and soy hulls: 1300 m2/g). TEM images indicated high exfoliation, explaining the change in surface area values. Under the same current density (500 mA/g) the cycling performance of the ACs increased as the surface area increased significantly.

Corn pericarp pretreated with dilute acid: bioconversion of sugars in the liquid fraction to ethanol and studies on enzymatic hydrolysis of the solid fraction

Corn pericarp (CP) results from wet milling of the corn industry. It is an abundant agro-industrial byproduct in Mexico, with potential use as sugars source to obtain ethanol and other economically relevant chemicals. In this work, CP was pretreated with dilute sulfuric acid at 121 °C; using a 23 full factorial design, factors were sulfuric acid, reaction time, and CP concentration. After pretreatment, the capacity of activated charcoal to remove inhibitory compounds in the liquid fraction was studied. Then, the detoxified liquid fraction was fermented using Scheffersomyces stipitis, whereas the solid fraction was exposed to enzymatic hydrolysis by a commercial cellulase (Cellic® CTec2). The most promising pretreatments utilized 2% (v/v) sulfuric acid, 20% (w/v) of CP, and 30 min reaction time producing 109.38 ± 6.73 g/L reducing sugars. The solid fraction obtained from CP pretreatment resulted in cellulose conversion up to 85.60% ± 1.87% after 94 h, significantly higher than conversion achieved using untreated CP of 32.54% ± 5.58%. The detoxification process allowed yeast fermentation to reach ethanol yields (g ethanol/g consumed substrate) between 0.09 ± 0.02 and 0.29 ± 0.006. S. stipitis was able to produce between 4.62 ± 1.73 and 14.22 ± 0.98 g/L of ethanol from the hydrolyzed liquid fraction. The dilute acid pretreatment on CP produced a solid fraction, which upon enzymatic treatment caused high cellulose conversion into reducing sugars. Additionally, the fermentability of the sugars present in the liquid fraction was increased after the detoxification process. Thus, CP is a material that shows good potential to obtain value-added products such as ethanol.

Effect of sulfur dioxide and lactic acid in steeping water on the extraction of anthocyanins and bioactives from purple corn pericarp

AbstractBackground and objectivesPurple corn can be an economical source of anthocyanins, a natural alternate to synthetic FD&amp;C Red 40 dye in foods. The effects of steeping purple corn pericarp in wet milling chemicals, namely sodium metabisulfite and lactic acid, and milling on the extraction of anthocyanins, polyphenols, flavonoids, and tannins were studied.FindingsSteeping water with 2,000 ppm SO2 contained total monomeric anthocyanins (TA) equivalent of 20.5 ± 1.5 mg cyanidin‐3‐O‐glucoside (C3G)/g pericarp, higher than using only water (7.1 ± 0.6 mg C3G/g pericarp). In the treatment with SO2 and 5,000 ppm lactic acid, TA concentration was 22.9 ± 0.2 mg C3G/g pericarp. This was due to increased extraction of C3G and condensed forms of anthocyanins. Polyphenols and tannins were higher in SO2 treatments while flavonoid concentration was not different. Chroma was positively correlated with anthocyanins (r = 0.999) and tannins (r = 0.994). Ball milled pericarp fractions yielded the highest amount of anthocyanins.ConclusionsAnthocyanin recovery from purple corn pericarp can be significantly increased using a milling step prior to SO2‐based extraction.Significance and noveltyA novel method for increasing anthocyanin yields from purple corn is proposed.

Phase resolved method using the Hill-Climbing Metaheuristic Algorithm applied for the spectral separation from photoacoustic spectra of chilli pepper skin and yellow corn pericarp

The phase-resolved method has been widely used in photoacoustic spectroscopy for separating the contribution of different optical absorption centers to a spectrum. However, the procedure is lengthy, tedious and without precision control, because one has to calculate several spectra to search for the phase angle at which only one contribution is present every time. In this work, this limitation is avoided by the implementation of a method as a search and optimization problem using the Hill Climbing Metaheuristic Algorithm. As test examples, the photoacoustic spectra of chilli fruit skin of Anaheim type (Capsicum Annuum L.) and yellow corn grain pericarp of dent type (Zea Mays L.) were analyzed in the wavelength ranges where there is optical absorption of the photoprotective pigments of these samples.