Agro-industrial Residues Research Articles

Do biodegradable food packaging films from agro-food waste pay off? A cost-benefit analysis in the context of Europe

Bio-based polymers are increasingly attracting attention as a solution to reducing the consumption of non-renewable resources and curbing the accumulation of fossil-based plastic waste. In this study, we analyze the economics of a new packaging film based on a polylactic acid–polyhydroxybutyrate blend (PLA-PHB), with PHB obtained from agro-industrial residues (potato peels). We model various sizes of biorefineries using the new biotechnology in Europe. For a four-year payback period, which is generally accepted in the industry, the calculated minimum product selling price ranges from 9.7 euros per kilogram to 37.2 euros per kilogram, depending, among other factors, on the production capacity of the biorefinery. We have incorporated the uncertainty over the model parameters in a Monte Carlo simulation and investigated the relative impact of individual factors on the minimum product selling price. Overall, the results indicate that the bio-based feedstock availability is the most influential factor on the profitability of the new biotechnology.

Eco-friendly particleboard production from coconut waste valorization.

Reusing agro-industrial waste does not only help to mitigate environmental impact but also enables valorization through the development of new products. The aim is to enhance the physical and mechanical properties of particleboard panels produced with Eucalyptus wood and different proportions of waste products-coconut fiber (Cocos nucifera L.). Physical properties (density, water absorption, and thickness swelling) and mechanical properties (static bending and internal bond resistance) were assessed, and panels reinforced with coconut fiber showed the best qualities with higher density, greater dimensional stability, and less water absorption. Static bending resistance and internal bond resistance also increased significantly. This demonstrated the potential of achieving compatible characteristics for civil construction and furniture production through the inclusion of waste material. The impact of this research is obtained from the utilization of an important agro-industrial residue in the manufacture of permanent composites.

Influence of Sintering on Thermal, Mechanical and Technological Properties of Glass Foams Produced from Agro-Industrial Residues.

This study investigates the technological, thermal, mechanical, and technological properties of glass foams produced with soda-lime glass residues and rice husk ash sintered at 850–950 °C. The results for apparent density (0.28–0.30 g/cm3), porosity (82–87 ± 4%), compressive strength (1.18 ± 0.03–1.25 ± 0.03 MPa), and thermal conductivity (0.283–0.326 W/mK) are within the limits for commercial foams. The volumetric expansion potential and low thermal conductivity of the glass foams produced favor their use as thermal insulating materials in coat walls, thus improving thermal comfort in the construction sector. The results of X-ray fluorescence show that the foam glass is of the soda-lime type (SiO2, Na2O, and CaO), the rice husk ash is rich in SiO2, CaO, Na2O, Al2O3, K2O and Fe2O3, and the calcium carbonate is rich in CaO. The glass foams produced in this study are promising because they present more economical and efficient manufacturing, resulting in lightweight materials with thermal insulating properties that can be used in the construction sector. These glass foams also reduce the consumption of natural and synthetic raw materials, adding value to the waste used in this study by transforming them into co-products, thus favoring the economic circulation of the region.

Development of sustainable biocomposite panels assisted with deep eutectic solvent pretreatment of agro-industrial residue

The pretreatment of lignocellulosic biomass in biorefineries is a very promising path for their conversion into value-added products. However, development of sustainable pretreatment for efficient conversion of lignocellulosic biomass into value-added materials is still an emergent and challenging field. Herein, a new direction for the utilization of deep eutectic solvent (DES) pretreatment of lignocellulosic biomass in the fabrication of compression-molded biocomposite panels was studied. The impact of untreated and DES-treated fibers of three types of lignocellulosic waste—corn stover (CS), peanut shell powder (PSP), and sugarcane bagasse (SCB)—on the properties of biocomposite panels using urea–formaldehyde binder was investigated. Cellulose-rich fiber (CRF) was extracted by pretreating lignocellulosic materials with choline chloride and glycerol-based synthesized DES under mild operating conditions, and high solids loading and mechanical and water absorption properties of the biocomposite board prepared from untreated and DES-treated fibers were measured. The effect of DES pretreatment on the properties of lignocellulosic fibers was evaluated using Fourier transform infrared spectroscopy (FTIR), lignocellulosic compositional analysis (LCA), thermogravimetric analysis (TGA), and X-ray diffraction analysis (XRD). These analyses revealed that cellulosic content and thermal stability of all DES-treated fibers improved compared to untreated samples. The biocomposite board made from DES-treated fibers had higher strength and modulus than the untreated composite board, as determined by the three-point bending test. Specifically, the modulus of rupture (MOR) and modulus of elasticity (MOE) of SCB biocomposite panels increased from 26.15 MPa and 1564.65 MPa to 31.28 MPa and 1871.74 MPa in DES-treated panels, respectively. These findings suggest that the novel DES-based pretreatment could be a promising sustainable processing strategy for converting agro-industrial waste into CRF to fabricate wood-composite panels with a wide range of furniture and construction applications.

Cheese Whey as a Potential Feedstock for Producing Renewable Biofuels: A Review

Agro-industrial residues such as bagasse, pomace, municipal residues, vinasse and cheese whey are an environmental problem around the world, mainly due to the huge volumes that are generated because of the food production to satisfy the nutritional needs of the growing world population. Among the above residues, cheese whey has gained special attention because of its high production with a worldwide production of 160 million tons per year. Most of it is discarded in water bodies and land causing damage to the environment due to the high biological oxygen demand caused by its organic matter load. The environmental regulations in developing countries have motivated the development of new processes to treat transform cheese whey into added-value products such as food supplements, cattle feed and food additives. In addition, during the last decade, several processes and technologies have been developed to produce bioenergy through the biotechnological process using cheese whey as a potential feedstock. This review discusses the production of bioethanol, biohydrogen, biomethane and microbial lipid-biodiesel production using cheese whey as a potential substrate.

Assessing the feasibility of an integrated CLC-methanation system using solar dried and torrefied biomasses as a feedstock

To promote the integration between solar-driven torrefaction, Power-to-Gas, and Chemical Looping Combustion (CLC) systems, this work numerically analyzes the performances of a novel process layout. Several agro-industrial residues were considered as fuels. CuO supported on zirconia and Ni supported on alumina were considered as oxygen carrier and methanation catalyst, respectively. Torrefied samples were purposely obtained by means of experimental runs carried out for 30 min at 300 °C in a lab-scale fixed bed reactor under a nitrogen atmosphere. Under the adopted conditions it was attained an increase in the lower heating values (LHV) of the selected feedstocks by about 14–49 %, depending on the different composition and reactivity of the parent biomass. Based on these data, it was estimated that, with respect to 10 kg h−1 torrefied biomass fed to the CLC system, a total thermal power production in the range of 28–58 kW can be achieved. CO2 conversion degrees of above 98 % were evaluated for the methanation unit in all considered scenarios. Considering different locations in Italy, PV field sizes ranging from 45 m2 up to 1392 m2 were evaluated for the solar-driven torrefaction unit. Wider sizes were calculated for the hydrogen production one, ranging from 3366 m2 up to 5598 m2. Eventually, an electric energy storage efficiency of around 16 % was assessed for the proposed layout. Finally, it was found that moving from the adopted torrefied feedstocks to the produced gaseous fuel, an increase in the LHV by about 44–55 % can be attained, while concurrently, CO2 emissions are favorably decreased by 98 %.

Natural Substrates and Culture Conditions to Produce Pigments from Potential Microbes in Submerged Fermentation

Pigments from bacteria, fungi, yeast, cyanobacteria, and microalgae have been gaining more demand in the food, leather, and textile industries due to their natural origin and effective bioactive functions. Mass production of microbial pigments using inexpensive and ecofriendly agro-industrial residues is gaining more demand in the current research due to their low cost, natural origin, waste utilization, and high pigment stimulating characteristics. A wide range of natural substrates has been employed in submerged fermentation as carbon and nitrogen sources to enhance the pigment production from these microorganisms to obtain the required quantity of pigments. Submerged fermentation is proven to yield more pigment when added with agro-waste residues. Hence, in this review, aspects of potential pigmented microbes such as diversity, natural substrates that stimulate more pigment production from bacteria, fungi, yeast, and a few microalgae under submerged culture conditions, pigment identification, and ecological functions are detailed for the benefit of industrial personnel, researchers, and other entrepreneurs to explore pigmented microbes for multifaceted applications. In addition, some important aspects of microbial pigments are covered herein to disseminate the knowledge.

Proximal and mineral composition analysis of castilla squash seeds (C. moschata), green pea (P. sativum) and green bean (P. vulgaris) for use in 4.0 Agribusiness

Objective: To determine the proximal and mineral composition analysis of of castilla squash seeds (C. moschata), green pea (P. sativum) and pinto saltillo green bean (P. vulgaris). Design/methodology/approach: The contents of macronutrients (carbohydrates, fats, crude fiber, protein, and ash) and micronutrients (minerals) of the evaluated species were determined using the AOAC standard procedures, and the quantification of minerals was performed by mass spectrometry with inductively coupled plasma. A variance analysis and means comparison were performed with Tukey’s test (α = 0.05). Results: The squash seeds with shells contain 291,500 ppm of protein, 417,000 ppm of fat, 66,700 ppm of carbohydrates, 134,000 ppm of crude fiber, 972,319.678 ppm of phosphorus, 3,380.09158 ppm of potassium and 3,183.2744 ppm of magnesium. The whole pea pod has 230,600 ppm of protein, 17,200 ppm of fat, 456,000 ppm of carbohydrates, 220,800 ppm of crude fiber, 5,438.18,991 ppm of phosphorus, 7,349.23753 ppm of potassium and 1,719.56882 ppm of magnesium. The whole green bean pods had a content of protein (185100 ppm), fat (2540 ppm), carbohydrates (377500 ppm), fiber (208000 ppm), phosphorus (6068.44661 ppm), potassium (15626.9991 ppm) and magnesium (17222.16567 ppm)). Study limitations/implications: Studies on the chemical characteristics of other agroindustrial residues should be carried out. Findings/conclusions: The foods analyzed have adequate characteristics to satisfy the demands with respect to some macronutrients and micronutrients. They can optimize the availability of nutrients in the generation of natural or synthetic foods that can change the future.

Antimicrobial potential of filamentous fungi growing on renewable substrates

The bioprospecting of secondary metabolites with antimicrobial action produced by filamentous fungi isolated from various ecosystems using agro-industrial residues is of considerable importance, since it reconciles the discovery of new antimicrobial agents with the reduction of environmental impacts adding economic value to wastes. The present paper investigated the potential of filamentous fungi for antimicrobial metabolites production using alternative media based on corn steep liquor, cassava wastewater and glycerol as substrates in different combinations. From 15 filamentous fungi assayed in preliminary screening, Paecilomyces variotii UCP 0334, Aspergillus flavus UCP 0316, Aspergillus foetidus UCP 0360, Aspergillus niger UCP 1064 e Aspergillus sp. 74M4 showed higher activity against all tested bacteria. After submerged fermentation in media containing corn steep liquor, cassava wastewater and glycerol, P. variotii UCP 0334 exhibitted greater activity and spectrum of action with inhibition halos ranging from 7 to 28 mm in diameter against all Gram negative and positive bacteria tested regardless of the culture medium type. It is worth mentioning that all fungi in alternative medium containing cassava wastewater and glycerol (CWWG) showed inhibitory activity against 3 bacteria with inhibition halos ranging from 9 to 15 mm. On the other hand, the medium containing corn steep liquor and glycerol (CSLG) favored higher biomass yield for all fungi. These results stimulate further studies of identification and characterization of the secondary metabolites produced by the selected fungi with a view to discovering new antimicrobial drugs.

Insights on the physico-chemical properties of alkali lignins from different agro-industrial residues and their use in phenol-formaldehyde wood adhesive formulation

The current study investigates for the first time the physico-chemical performances of lignins from cactus waste seeds (CWS) and spent coffee (SC) in comparison to previously isolated lignins from sugar byproducts (bagasse (SCB) and beet pulp (SBP)). In this work, lignin-phenol formaldehyde (LPF) resins were formulated using various lignin loadings (5–30 wt%), characterized and applied in the manufacturing of plywood panels. Several characterization techniques were applied to identify the chemical and morphological properties, thermal stability, and phenolic content of the extracted lignins, as well as the bonding strength and wood failure of the formulated resins. Results showed that the CWS and SC could be considered as an important source for lignin recovery with a considerable yield of 15.46 % and 27.08 % and an important hydroxyl phenolic content of 1.26 mmol/g and 1.36 mmol/g for CWS and SC, respectively. Interestingly, 20 wt% of extracted lignins in PF adhesives were the optimal formulation showing an improved modulus of elasticity (MOE) of about 3505, 3536 and 3515 N/mm2, and a higher modulus of rupture (MOR) of about 55, 55 and 56 N/mm2 for panels containing CWS, SC and SCB-lignins, respectively, over the reference panels (MOE = 3198 N/mm2 and MOR = 48 N/mm2). Additionally, formaldehyde emission from plywood remarkably decreases by up to 20 % when lignin was incorporated into the PF matrix. Herein, the treatment of the CWS and SC for the extraction of alkali lignin and its application showed a new route to produce high added-value products from underused residues.

Mechanical response of filtered and compacted iron ore tailings with different cementing agents: Focus on tailings-binder mixtures disposal by stacking

• Key parameters for the dosage of mixtures of compacted filtered IOT–RHA–CL based AAC for dry stacking. • Mechanical performance linked to η/B iv and curing periods of compacted filtered IOT AAC containing agro-industrial residues. • Predictive correlations of durability to assist in the design of disposition of compacted cemented dry tailings piles. • The use of agro-industrial residues seeks to evaluate the potential development of an eco-friendly binder. The high volume of mining tailings generated imposes difficulties regarding the final disposal of these materials, commonly requiring large structures for containment. Traditionally, mining tailings are disposed in containment dams. However, this containment system ends up presenting high associated risks, with incidents of great environmental, social, and economic impact being recorded. This situation raises the need for the development of new disposal technologies. The disposal of agglomerated and stacked dry filtered tailings is a recent methodology that reduces dependency of raising dams. This technique has become viable with recent advances in large-scale material dewatering technologies. The present study seeks to evaluate the mechanical behaviour of cemented iron ore tailings comparing the yield of a commercial binding agent (Portland cement - PC) and an alternative binder (alkali-activated cement - AAC). Commonly, conventional hydraulic cements have a high energy expenditure in their production, while alkali-activated binders can be produced from residues rich in aluminosilicates. The results have shown an enhanced mechanical response of tailings-binder agent mixtures, based on tests of unconfined compressive strength, split tensile strength, and durability by cycles of wetting, drying, and brushing, being verified the potential use for the development of alternative disposal methods. The correlation of the mechanical parameters with the porosity by volumetric content of binder index (η /B iv ) is also verified. Present study observes the potential for predicting the mechanical behaviour of tailings-cement mixtures through dosing curves for different mechanical tests, curing periods and binders.

Bioconversion of agro-industrial residues as a protein source supplementation for multiparous Holstein Thai crossbreed cows.

The purpose of this field study was to compare the effects of top-dressing tropical lactating cows with soybean meal (SBM) or citric waste fermented yeast waste (CWYW) on intake, digestibility, ruminal fermentation, blood metabolites, purine derivatives, milk production, and economic return. Sixteen mid-lactation Thai crossbreeds, Holstein Friesian (16.7 ± 0.30 kg/day milk yield and 490 ± 40.0 kg of initial body weight) were randomly allocated to two treatments in a completed randomized design: SBM as control (n = 8) or CWYW (n = 8). The feeding trial lasted for 60 days plus 21 days for treatment adaptation. The results showed that total dry matter intake, nutrient intake, and digestibility did not (p>0.05) differ between SBM and CWYW top-dressing. Ruminal pH and the protozoal population did not (p>0.05) differ between SBM and CWYW top-dressing. After 4 hours of feeding, CWYW top-dressing showed greater ammonia nitrogen, plasma urea nitrogen, and bacterial population compared with the top-dressing of SBM. Volatile fatty acids and purine derivatives were not different (p>0.05) between SBM and CWYW top-dressing. For milk urea nitrogen, there was a greater (p<0.05) and somatic cell count was lower (p<0.05) for cows fed the CWYW top-dress compared to cows fed the SBM top-dress. The cost of the top-dress and total feed cost were less (p<0.05) for CWYW compared to SBM top-dressing, at 0.59 vs 1.16 US dollars/cow/day and 4.14 vs 4.75 US dollars/cow/day, respectively. In conclusion, CWYW could be used as an alternative protein source to SBM without having a negative impact on tropical lactating cows.

EXTRACTION AND ACTIVITIES OF CRUDE PROTEASES FROM SOLID STATE FERMENTATION OF Aspergillus nigeR GROWN ON VARIOUS AGRO WASTE

Agro-industrial residues are generally considered the best substrates for the solid-state fermentation process. Food processing wastes such as shells of nuts and eggs in Nigeria are usually disposed in dumpsites or are incinerated, causing environmental pollution. This study extracted, estimated and compared enzyme activities from Aspergillus niger under solid-state fermentation (SSF) by utilizing Ground nut shell (GS), Bambara nut shell(BS), Guinea fowl egg shell(GFS) and Layer egg shells (LES) powder as solid substrates. The Agro wastes were dried under the sunlight for four days, ground using a laboratory pestle and mortar separately and sieved to obtain fine powder. The powder was sterilized, supplemented with sodium acetate buffer and pure casein, inoculated with the fungi then left to ferment for six days. The crude extract of the substrates were obtained by filtration and centrifugation. The extracts were assayed for enzyme activity using Sigma Aldrich’s method of assay. The result obtained from the assay demonstrated that proteases were active in all the extracts. However, there was significantdifference (P &lt; 0.05) in protease activities in the samples studied. The result revealed that BS and LES showed the highest enzymatic activities (0.797± 0.035 μ/ml), (0.788 ± 0.028 μ/ml), (0.574 ± 0.032 μ/ml), (0.590± 0.040 μ/ml) at 0.2, 0.4, 0.6 and 0.8ml of the crude enzyme extract volume concentrations respectively followed by GS which had the enzymatic activities (0 .456 ±0.001 μ/ml), (0.391 ± 0.003 μ/ml), (0.335 ± 0.003 μ/ml), (0.205± 0.032 μ/ml) at the volume extract volume concentrations of 0.2, 0.4, 0.6, 0.8ml respectively, meanwhile guinea fowl egg shell had the least enzymatic activities (0.401± 0.028 μ/ml), (0 .336 ± 0.047 μ/ml), (0.250 ± 0.018 μ/ml), (0.255 ± 0.010 μ/ml) at the volume of crude enzyme extract of 0.2, 0.4, 0.6, 0.8ml respectively. In all the shells the highest proteases activities were recorded at 0.2ml of the crude extract volume concentration and the least proteases activities were recorded at 0.8ml of then crude extract volume concentration. This study has proven that proteases were extracted and active from solid state fermentation of Aspergillus niger grown on various agro waste, Therefore proper utilization of these agro-wastes in industrial and scientific settings will not only serve as means of polluted environmental remediation but also as an iualternative to commercially available substrates for microbial growth.

Assessment of Different Lactic Acid Bacteria Isolated from Agro-Industrial Residues: First Report of the Potential Role of Weissella soli for Lactic Acid Production from Milk Whey

The production of lactic acid (LA) through the microbial conversion of agro-industrial residuals is an important process in the biotechnology industry. The growth kinetics of 30 strains of lactic acid bacteria (LAB) isolated from agro-industrial residues were determined and nine strains were selected for microbioreactor fermentation. Lactiplantibacillus pentosus_70-1 (1.662) and L. pentosus_19-2 (1.563) showed the highest OD600 values, whereas the highest growth rates were observed for L. pentosus_19-2 (0.267 h−1) and Weissella soli_31 (0.256 h−1). The production of LA and acetic acid (AA), glucose consumption, and metabolic profiles were determined, without finding significant differences in the production of LA; however, W. soli_29 produced the highest amount of LA (20.833 gL−1) and was able to metabolize most of the studied carbohydrates. Based on these results, W. soli_29 was chosen for a 20 h fermentation in a 7 L bioreactor using both standard medium and milk whey supplemented medium. W. soli_29 produced 16.27 gL−1 and 7.21 gL−1 of LA in each of these mediums, respectively. These results show the underlying potential of Weissella strains for biotechnological applications. Additional analysis which should contemplate different agro-industrial residues and other conditions in bioreactors must be carried out.

Is nanofiltration an efficient technology to recover and stabilize phenolic compounds from guava (Psidium guajava) leaves extract?

Guava leaves (Psidium guajava) are popularly known due to their effects antidiabetic, antihypertensive, anti-inflammatory, antidiarrheal, and functional properties. Processes for the concentration of these extracts are necessary since their pharmacological effects are dose-dependent. In this work, guava leaves aqueous extract (GE) concentration was carried out in nanofiltration (NF) equipment. Process performance was evaluated in terms of permeate flux, flux decline modeling, and extract quality (compounds characterization, total phenolic content and antioxidant activity). NF allowed an increase in phenolic compounds next to 20-times, retention coefficients of total phenolic compounds (99%) and enhanced antioxidant capacity (an increase of 4 and 9-fold for ABTS and DPPH, respectively) compared to the initial GE. Forty-two phenolic compounds were identified, being catechin (594.56 mg mL−1) and vescalagin (295.39 mg mL−1) the main compounds. All phenolics presented a significant increase (p < 0.05) after the concentration suggesting that NF is efficient for the recovery and concentration of bioactive compounds and poses as an alternative to obtain functional products and improve added value in agro-industrial residues.

Efficient saccharification of Lycium barbarum leaf biomass by using enzyme cocktails produced by a novel fungus Aspergillus costaricensis LS18

The utilization of agro-industrial residues is an interesting issue contributing to sustainable development and environmental protection. Lycium barbarum leaves (LBL) are agro-industrial residues of the L. barabrum berry cultivation and seriously underutilized, leading to resource waste and environmental pollution. In this study, we prepared cost-effective enzyme cocktails with high xylanase activity from a novel soil-derived fungal strain Aspergillus costaricensis LS18. The xylanase activity of these on-site produced enzyme cocktails was 3.49 ± 0.55 U/mL. Through the hydrolysis using the enzyme cocktails with 6% substrate loading at 45 °C for 12 h, 86.57 ± 1.81% of total reducing sugars (RS) from LBL was released. The concentration of RS in the hydrolysates reached 8.17 ± 0.33 mg/mL. In this study, LBL were added values by two mutually independent bioprocess ways. On the one hand, LBL were used as the only nutrients in the medium for the on-site production of enzyme cocktails by fermentation. On the other hand, through hydrolysis using this enzyme cocktail, LBL biomass was efficiently hydrolyzed and fermentable monosugars were gained. This study could benefit to the exploitation of LBL resources and provide the references for utilization of other agro-industrial residues.

Modeling biosurfactant production from agroindustrial residues by neural networks and polynomial models adjusted by particle swarm optimization.

Biosurfactants are molecules with wide application in several industrial processes. Their production is damaged due to inefficient bioprocessing and expensive substrates. The latest developments of strategies to improve and economize the biosurfactant production process use alternative substrates, optimization techniques, and different scales. This paper presents a study to compare the performances of classical (polynomial models) and modern tools, such as artificial intelligence to aid optimization of the alternative substrate concentration (alternative based on beet peel and glycerol) and process parameters (agitation and aeration). The evaluation was developed in two different scales: Erlenmeyer flask (100mL) and bioreactor (7 L). The intelligent models were implemented to verify the ability to predict the emulsification index and biosurfactant concentration in smaller scale and the biosurfactant concentration and the superficial tension reduction (STR) in bigger scale, resulting in four different situations. The overall results of the predictions led to artificial neural networks as the best performing modeling tool in all four situations studied, with R2 values ranging from 0.9609 to 0.9974 and error indices close to 0. Also, four different models (Wu, Contois, Megee, and Ghose-Tyagi) were adjusted by particle swarm optimization (PSO) in order to describe the kinetics of biosurfactant production. Contois model was the only one to present R2 ≥ 0.97 for all monitored variables. The findings described in this work present an adjusted model for the prediction of biosurfactant production and also state that the most adjusted kinetic model for further studies on this process is Contois model, leading to the conclusion that biomass growth is limited by a single substrate, considering only glucose.

New sustainable and robust catalytic supports for palladium nanoparticles generated from chitosan/cellulose film and corn stem biochar.

The production of sustainable catalytic supports for palladium nanoparticles is always desired, even more so through the recovery of biomass residues. In this sense, two different solids were investigated — chitosan/cellulose film and corn stem biochar — as catalytic supports of palladium nanoparticles. The solids were carefully characterized and tested in the Suzuki-Miyaura reaction, a typical cross-coupling reaction. The developed catalytic systems proved to be efficient and sustainable, promoted the formation of target products very well, and demanded green reactants under environmentally appropriate conditions. With the results shown in the manuscript, it is expected to contribute to the valorization of biomass and agro-industrial residues in the development of new catalysts for the chemical industry.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-022-22616-6.

Optimization and production of alpha-amylase using Bacillus subtilis from apple peel: Comparison with alternate feedstock

Degradable waste generated from food processing industries has immense potential for producing valuable products. Apples constitute among the most widely consumed fruits in the food processing industry, but their peels remain unutilized. We explored the possibility of using apple peel as feedstock for production of alpha-amylase- a commercially important enzyme with role in food industry and bio-ethanol production that is critical to support nutrition and energy security. The utilization of locally sourced apple peel as feedstock, optimization of the conditions for the production of alpha-amylase through solid-state fermentation and comparison with potato peel-another widely available feedstock option is done. The Bacillus subtilis BS1934 strain was identified as a promising strain that could produce alpha-amylase efficiently at 50 0C. The obtained values i.e., 17468 and 5229 U/L of alpha-amylase from apple and potato peel, respectively through solid state fermentation in eight days were considered as optimum. The enzyme titres were 3-fold higher with apple peel as compared to potato peel in the medium, indicating superior quality of apple peel feedstock as compared to potato for amylase production. The production of amylase using agro-industrial residues, as apple peel may emerge as a cost-effective alternative to amylase from microbial sources for industrial purpose.

Carbon dots decorated magnetite nanocomposite obtained using yerba mate useful for remediation of textile wastewater through a photo-Fenton treatment: Ilex paraguariensis as a platform of environmental interest-part 2.

Two carbon dots (CD) with diameters of 4.9 ± 1.5 and 4.1 ± 1.2nm were successfully synthesized through an acid ablation route with HNO3 or H2SO4, respectively, using Ilex paraguariensis as raw material. The CD were used to produce magnetite-containing nanocomposites through two different routes: hydrothermal and in situ. A thorough characterization of the particles by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), dynamic light scattering (DLS), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) indicates that all nanomaterials have spherical-like morphology with a core-shell structure. The composition of this structure depends on the route used: with the hydrothermal route, the shell is composed of the CD, but with the in situ process, the CD act as nucleation centers, and so the iron oxide domains are in the shell. Regarding the photocatalytic mechanism for the degradation of methyl orange, the interaction between the CD and the magnetite plays an important role in the photo-Fenton reaction at pH 6.2, in which ligand-to-metal charge transfer processes (LTMCT) allow Fe2+ regeneration. All materials (100ppm) showed catalytic activity in the elimination of methyl orange (8.5ppm), achieving discoloration of up to 98% under visible irradiation over 400nm in 7h. This opens very interesting possibilities for the use of agro-industrial residues for sustainable synthesis of catalytic nanomaterials, and the role of the interaction of iron-based catalysts with organic matter in heterogeneous Fenton-based processes.