Valorization applications of pineapple and papaya byproducts in food industry.

The recent increase in the harvesting and industrial processing of tropical fruits such as pineapple and papaya is leading to unavoidable amounts of byproducts rich in valuable compounds. Given the significance of the chemical composition of these byproducts, new research avenues are opening up to exploit them in the food industry. In this sense, the revalorization of pineapple and papaya byproducts is an emerging trend that is encouraging the full harnessing of these tropical fruits, offering the opportunity for developing innovative value-added products. Therefore, the main aim of this review is to provide an overview of the state of the art of the current valorization applications of pineapple and papaya byproducts in the field of food industry. For that proposal, comprehensive research of valorization applications developed in the last years has been conducted using scientific databases, databases, digital libraries, and scientific search engines. The latest valorization applications of pineapple and papaya byproducts in the food industry have been systematically revised and gathered with the objective of synthesizing and critically analyzing existing scientific literature in order to contribute to the advancement of knowledge in the field of tropical byproduct revalorization providing a solid foundation for further research and highlighting scientific gaps and new challenges that should be addressed in the future.

Metal-organic frameworks-based moisture responsive essential oil hydrogel beads for fresh-cut pineapple preservation.

The preservation of fresh-cut fruits and vegetables has attracted attention to the shelf-life reduction caused by high humidity. Herein, alginate/copper ions cross-linking, in-situ growth and self-assembly techniques of metal-organic frameworks (MOFs) were utilized to prepare a moisture responsive hydrogel bead (HKUST-1@ALG). As the multistage porous structure formation, tea tree essential oil (TTO) load capacity in hydrogel bead (TTO-HKUST-1@ALG) was increased from 6.1% to 21.6%. TTO-HKUST-1@ALG had excellent moisture response performance, and the release rates of TTO increased from 33.89% to 70.98% with moisture increasing from 45% to 95%. Besides, TTO-HKUST-1@ALG exhibited excellent antimicrobial, antioxidant capacity, and biocompatibility. During storage, TTO-HKUST-1@ALG effectively improved the cell membrane integrity by maintaining the balance of reactive oxygen species metabolism. The degradation of cell wall structure and tissue softening were delayed by inhibiting the cell wall-degrading enzymes activity. Briefly, TTO-HKUST-1@ALG improved the storage quality and extended shelf-life of fresh-cut pineapple, which was a promising preservative.

Reliable detection of malachite green by self-assembled SERS substrates based on gold-silicon heterogeneous nano pineapple structures.

Morphology regulation of heterodimer nanoparticles and the use of their asymmetric features for further practical applications are crucial because of the rich optical properties and various combinations of heterodimers. This work used silicon to asymmetrically wrap half of a gold sphere and grew gold branches on the bare gold surface to form heterogeneous nano pineapples (NPPs) which can effectively improve Surface-enhanced Raman scattering (SERS) properties through chemical enhancement and lightning-rod effect respectively. The asymmetric structures of NPPs enabled them to self-assemble into the monolayer membrane with consistent branch orientation. The prepared substrate had high homogeneity and better SERS ability than disorganized substrates, and achieved reliable detection of malachite green (MG) in clams with a detection limit of 7.8 × 10-11 M. This work provided a guide to further revise the morphology of heterodimers and a new idea for the use of asymmetric dimers for practically photochemical and biomedical sensing.

Production of PLA/cellulose derived from pineapple leaves as bio-degradable mulch film.

Mulch films were fabricated from polylactic acid (PLA) with cellulose nanocrystals (PNC) extracted from pineapple leaves. The PNC was modified by incorporating 4 wt% triethoxyvinylsilane (TEVS), designated as 4PNC, to enhance its interaction with PLA. The films incorporated varying concentrations of PNC (1, 2, 4, and 8 wt%). The results indicated that higher PNC concentrations increased the water vapor permeability (WVP) and biodegradability of the composite films, while reducing light transmission. Films containing 4PNC, particularly at 4 wt% (PLA/4PNC-4), exhibited an 11.18 % increase in elongation at break compared to neat PLA films. Moreover, these films showed reduced light transmission, correlating with decreased weed growth, reduced WVP, and enhanced barrier properties, indicative of improved soil moisture retention. Additionally, PLA films with 4PNC demonstrated greater thermal degradation stability than those with unmodified PNC, suggesting enhanced heat resistance. However, there was no significant difference in aerobic biodegradation between the PLA films with PNC and those with 4PNC. This study confirms that TEVS-modified cellulose significantly enhances the properties of bio-composite films, making them more suitable for mulch film applications.

Valorization of Pineapple (Ananas comosus) By-Products in Milk Coffee Beverage: Influence on Bioaccessibility of Phenolic Compounds.

The industrial processing of pineapples generates a substantial quantity of by-products, including shell, crown, and core. Bromelain, a proteolytic enzyme found naturally in pineapple, including its by-products, may positively influence the bioaccessibility of phenolics from milk coffee. Therefore, this study aimed to assess how the inclusion of extracts from pineapple by-products, namely shell, crown and core, could impact the bioaccessibility of coffee phenolics when combined with milk. After measuring the proteolytic activity of pineapple by-products, the standardized in vitro digestion model of INFOGEST was employed to evaluate changes in total phenolic content, total antioxidant capacity, and individual phenolic compounds in different coffee formulations. The results showed that incorporating extracts from the crown or core in both black and milk coffee increased the bioaccessibility of total phenolics (from 93 to 114% to 105-129%) and antioxidants (from 54 to 56% to 84-87%), while this effect was not observed for the shell. Moreover, adding core extracts also enhanced the bioaccessibility of caffeoylquinic acids and gallic acid in milk coffee (from 0.72 to 0.85% and 109-155%, respectively). Overall, the findings of this study highlight that bromelain from pineapple core may have a favorable effect on the recovery of phenolic compounds in milk coffee, possibly due to its ability to cleave proteins. These outcomes point out that industrial by-products can be transformed into economic value by being reintroduced into the production process through suitable treatment instead of disposal.

Proteogenomic Gene Structure Validation in the Pineapple Genome.

MD2 pineapple (Ananas comosus) is the second most important tropical crop that preserves crassulacean acid metabolism (CAM), which has high water-use efficiency and is fast becoming the most consumed fresh fruit worldwide. Despite the significance of environmental efficiency and popularity, until very recently, its genome sequence has not been determined and a high-quality annotated proteome has not been available. Here, we have undertaken a pilot proteogenomic study, analyzing the proteome of MD2 pineapple leaves using liquid chromatography-mass spectrometry (LC-MS/MS), which validates 1781 predicted proteins in the annotated F153 (V3) genome. In addition, a further 603 peptide identifications are found that map exclusively to an independent MD2 transcriptome-derived database but are not found in the standard F153 (V3) annotated proteome. Peptide identifications derived from these MD2 transcripts are also cross-referenced to a more recent and complete MD2 genome annotation, resulting in 402 nonoverlapping peptides, which in turn support 30 high-quality gene candidates novel to both pineapple genomes. Many of the validated F153 (V3) genes are also supported by an independent proteomics data set collected for an ornamental pineapple variety. The contigs and peptides have been mapped to the current F153 genome build and are available as bed files to display a custom gene track on the Ensembl Plants region viewer. These analyses add to the knowledge of experimentally validated pineapple genes and demonstrate the utility of transcript-derived proteomics to discover both novel genes and genetic structure in a plant genome, adding value to its annotation.

Engineering pineapple peel cellulose nanofibrils with oxidase-mimic functionalities for antibacterial and fruit preservation.

In this study, an antibacterial material (CNF@CoMn-NS) with oxidase-like activity was created using ultrathin cobalt­manganese nanosheets (CoMn-NS) with a larger specific surface area grown onto pineapple peel cellulose nanofibrils (CNF). The results showed that the CoMn-NS grew well on the CNF, and the obtained CNF@CoMn-NS exhibited good oxidase-like activity. The imidazole salt framework of the CNF@CoMn-NS contained cobalt and manganese in multiple oxidation states, enabling an active redox cycle and generating active oxygen species (ROS) such as singlet molecular oxygen atoms (1O2) and superoxide radical (·O2-), resulting in the significant inactivation of Staphylococcus aureus (74.14%) and Escherichia coli (54.87%). Importantly, the CNF@CoMn-NS did not exhibit cytotoxicity. The CNF@CoMn-NS further self-assembled into a CNF@CoMn-NS paper with flexibility, stability, and antibacterial properties, which can effectively protect the wound of two varieties of pears from decay caused by microorganisms. This study demonstrated the potential of using renewable and degradable CNF as substrate combined with artificial enzymes as a promising approach to creating antibacterial materials for food preservation and even extending to textiles and biomedical applications.

In-situ synthesis of ZIF-8 on magnetic pineapple leaf biochar as an efficient and reusable adsorbent for methylene blue removal from wastewater.

The presence of organic dyes in aquatic systems poses a significant threat to ecosystems and human well-being. Due to recycling challenges, traditional commercial activated carbon is not cost-effective. To address this, an imidazolate acid zeolite framework-8 (ZIF-8)-modified magnetic adsorbent (ZMPLB-800) was synthesized through the in-situ formation of ZIF-8 and subsequent carbonization at 800 °C, using magnetic pineapple leaf biochar (MPLB) as a carrier. The porous structure of ZMPLB-800 facilitates the rapid passage of dye molecules, enhancing adsorption performance. ZMPLB-800 exhibited remarkable adsorption capacity for methylene blue (MB) across a pH range of 3-13, with a maximum adsorption capacity of 455.98 mg g-1. Adsorption kinetics and thermodynamics followed the pseudo-second-order kinetic model and Langmuir isotherm model. Mechanisms of MB adsorption included pore filling, hydrogen bonding, electrostatic interactions, π-π interactions, and complexation through surface functional groups. Additionally, ZMPLB-800 demonstrated excellent regeneration performance, recording a removal efficiency exceeding 87% even after five adsorption/desorption cycles. This study provides a novel strategy for treating dye wastewater with MOF composites, laying the foundation for waste biomass utilization.

Combining thermosonication microstress and pineapple peel extract addition to achieve quality and post-acidification control in yogurt fermentation.

This work investigated the effects of the combined use of thermosonication-preconditioned lactic acid bacteria (LAB) with the addition of ultrasound-assisted pineapple peel extracts (UU group) on the post-acidification potential, physicochemical and functional qualities of yogurt products, aimed at achieving prolonged preservation and enhancing functional attributes. Accordingly, the physical-chemical features, adhesion properties, and sensory profiles, acidification kinetics, the contents of major organic acids, and antioxidant activities of the differentially processed yogurts during refrigeration were characterized. Following a 14-day chilled storage process, UU group exhibited acidity levels of 0.5-2 oT lower than the control group and a higher lactose content of 0.07 mg/ml as well as unmodified adhesion potential, indicating that the proposed combination method efficiently inhibited post-acidification and delayed lactose metabolism without leading to significant impairment of the probiotic properties. The results of physicochemical analysis showed no significant changes in viscosity, hardness, and color of yogurt. Furthermore, the total phenolic content of UU-treated samples was 98 µg/mL, 1.78 times higher than that of the control, corresponding with the significantly lower IC50 values of DPPH and ABTS radical scavenging activities of the UU group than those of the control group. Observations by fluorescence inverted microscopy demonstrated the obvious adhesion phenomenon with no significant difference found among differentially prepared yogurts. The results of targeted metabolomics indicated the proposed combination strategy significantly modified the microbial metabolism, leading to the delayed utilization of lactose and the inhibited conversion into glucose during post-fermentation, as well as the decreased lactic acid production and a notable shift towards the formation of relatively weak acids such as succinic acid and citric acid. This study confirmed the feasibility of thermosonication-preconditioned LAB inocula, in combination with the use of natural active components from fruit processing byproducts, to alleviate post-acidification in yogurt and to enhance its antioxidant activities as well as simultaneously maintaining sensory features.

Sustainable production of cellulose and hemicellulose-derived oligosaccharides from pineapple leaves: Impact of hydrothermal pretreatment and controlled enzymatic hydrolysis.

Globally, the demands for sustainably sourced functional foods like prebiotic oligosaccharides have been constantly increasing. This study assessed the potential of pineapple leaves (PL) as lignocellulosic feedstock for sustainable production of cellulose and hemicellulose-derived oligosaccharides through its hydrothermal pretreatment (HT) followed by controlled enzymatic hydrolysis. PL was subjected to HT at 160, 175, and 190 °C for 20, 30, 60, and 90 min without any catalyst for xylooligosaccharide (XOS) production, whereas, the resulting solid content after HT was subjected to controlled enzymatic hydrolysis by commercial cellulase using conduritol B epoxide (0.5-5 mM) for glucooligosaccharides (GOS) production. HT at 160 °C for 60 min resulted in maximum yield of XOS and GOS at 23.7 and 18.3 %, respectively, in the liquid phase. Controlled enzymatic hydrolysis of HT treated (160 °C) PL solids for 20 and 30 min yielded âˆ¼ 174 mg cellobiose/g dry biomass within 24 h, indicating overall high oligosaccharide production.

An Evaluation of the Effects of Pineapple-Extract and Bromelain-Based Treatment after Mandibular Third Molar Surgery: A Randomized Three-Arm Clinical Study.

A three-arm, randomized, placebo-controlled clinical study was conducted to assess the impact of lyophilized pineapple extract with titrated bromelain (Brome-Inf®) and purified bromelain on pain, swelling, trismus, and quality of life (QoL) following the surgical extraction of the mandibular third molars. Furthermore, this study examined the need for Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) by comparing their effects with a placebo group. This study enrolled 42 individuals requiring the extraction of a single mandibular third molar under local anesthesia. The patients were randomly assigned to receive Brome-Inf®, purified bromelain, or a placebo orally, initiating treatment on the day of surgery and continuing for the next 7 days. The primary outcome measured was the requirement for NSAIDs in the three groups. Pain, swelling, and trismus were secondary outcome variables, evaluated postoperatively at 1, 3, and 7 days. This study also assessed the comparative efficacy of freeze-dried pineapple extract and single-component bromelain. Ultimately, the placebo group showed a statistically higher need for ibuprofen (from days 1 to 7) at the study's conclusion (p < 0.0001). In addition, reductions in pain and swelling were significantly higher in both the bromelain and pineapple groups (p < 0.0001 for almost all patients, at all intervals) than in the placebo group. The active groups also demonstrated a significant difference in QoL compared to the placebo group (p < 0.001). A non-significant reduction in trismus occurred in the treatment groups compared to the placebo group. Therefore, the administration of pineapple extract titrated in bromelain showed significant analgesic and anti-edema effects in addition to improving QoL in the postoperative period for patients who had undergone mandibular third molar surgery. Moreover, both bromelain and Brome-Inf® supplementation reduced the need for ibuprofen to comparable extents, proving that they are good alternatives to NSAIDs in making the postoperative course more comfortable for these patients. A further investigation with larger samples is necessary to assess the pain-relieving and anti-inflammatory impacts of the entire pineapple phytocomplex in surgical procedures aside from mandibular third molar surgery.

Effectiveness of Bacillus subtilis ANT01 and Rhizobium sp. 11B on the control of fusarium wilt in pineapple (Ananas comosus).

Pineapple (Ananas comosus) is commonly infected by Fusarium oxysporum, causal agent of the fusarium wilt disease. Conventionally, growers use synthetic fungicides to control the disease, which lead to environmental pollution, hazardous effects on non-target organisms and risks on human health. The aim of this work was to assess the effectiveness of Bacillus subtilis ANT01 and Rhizobium sp. 11B to control fusarium wilt on pineapple plants. Four treatments derived from a complete factorial design were tested under field conditions. Treatments composed of B. subtilis ANT01 and the combination B. subtilis ANT01-Rhizobium sp. 11B decreased disease severity by 94.4% and 86.1%, respectively. On the other hand, the treatment prepared with Rhizobium sp. 11B alone showed a reduction of 75.0%. Size of leaves and nutritional condition (SPAD units) of the biocontrol agents-treated plants showed no statistical differences. Moreover, B. subtilis ANT01 decreased by 46% the initial soil population of F. oxysporum, while Rhizobium sp. 11B, B. subtilis ANT01 plus Rhizobium sp. 11B and control, showed a population reduction of 12.5%, 24.2% and 23.0%, respectively. These results make evident the potential of B. subtilis ANT01 as biocontrol agent of the pathogen under field conditions.

Nutritional Composition and Therapeutic Potential of Pineapple Peel - A Comprehensive Review.

Pineapple (Ananas comosus), the succulent and vibrant tropical fruit, is a symbol of exoticism and sweetness that captures the hearts and palates of people around the world. The pineapple peel, often considered as waste, has garnered attention for its potential applications. The pineapple peel is rich in essential nutrients, including calcium, potassium, vitamin C, carbohydrates, dietary fiber, and water, making it beneficial for the digestive system, weight management, and overall balanced nutrition. It contains significant amounts of sugars such as sucrose, glucose, and fructose, along with citric acid as the predominant organic acid. The peel also contains bromelain, a proteolytic enzyme known for its digestive properties. Studies have highlighted the pharmacological properties of pineapple peel, such as its potential anti-parasitic effects, alleviation of constipation, and benefits for individuals with irritable bowel syndrome (IBS). Efforts are being made to promote the utilization of pineapple peel as a valuable resource rather than mere waste. Its applications range from the production of vinegar, alcohol, and citric acid to the development of various food products, including squash, syrup, jelly, and pickles. Further research and innovation are required to fully explore the potential of pineapple peel and establish sustainable practices for its utilization, contributing to waste reduction and the development of value-added products.

Preparation, characterization, and evaluation of ketoconazole-loaded pineapple cellulose green nanofiber gel.

The present study involves the isolation of cellulose nanofibers from pineapple crown waste by a combined alkali-acid treatment method. The extracted pineapple nanofibers were characterized by Fourier-transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, nuclear magnetic resonance, high-resolution transmission electron microscopy, and dynamic light scattering. The extracted pineapple nanofibers were then incorporated in Carbopol 934P containing ketoconazole to prepare a ketoconazole-loaded pineapple nanofibrous gel. The prepared gel formulation was evaluated for viscosity, spreadability, extrudibility, pH, drug content, and texture profile analysis. The anticipated gel formulation was further evaluated by in vitro drug release (98.57 ± 0.58 %), ex vivo drug permeation, cytotoxicity, and histopathological studies. The permeation of the drug through skin determined by the ex-vivo diffusion study was found to be 38.27 % with a flux rate of 4.06 ± 0.26 µg/cm2/h. Further, the cytotoxicity study of pineapple nanofiber and ketoconazole-loaded nanofiber gel displayed no cytotoxic on healthy vero cells in the concentration range from 10 to 80 µg/ml. The histopathological analysis exhibited no signs of distress and inflammation. In conclusion, ketoconazole-loaded pineapple nanofiber gel could be considered as a promising delivery system for topical applications.

Purification of pineapple bromelain by IMAC chromatography using chlorophyll-activated macroporous matrices.

This study investigated the purification of bromelain obtained from pineapple fruit using a new adsorbent for immobilized metal ion affinity chromatography (IMAC), with chlorophyll obtained from plant leaves as a chelating agent. The purification of bromelain was evaluated in batches from the crude extract of pineapple pulp (EXT), and the extract precipitated with 50 % ammonium sulfate (EXT.PR), the imidazole buffer (200 mM, pH 7.2) being analyzed and sodium acetate buffer, pH 5.0 + 1.0 NaCl as elution solutions. All methods tested could separate forms of bromelain with molecular weights between ±21 to 25 kDa. Although the technique using EXT.PR stood out in terms of purity, presenting a purification factor of around 3.09 ± 0.31 for elution with imidazole and 4.23 ± 0.12 for acetate buffer solution. In contrast, the EXT methods obtained values between 2.44 ± 0.23 and 3.21 ± 0.74 for elution with imidazole and acetate buffer, respectively, for purification from EXT.PR has lower yield values (around 5 %) than EXT (around 15 %). The number of steps tends to reduce yield and increase process costs, so the purification process in a monolithic bed coupled to the chromatographic system using the crude extract was evaluated. The final product obtained had a purification factor of 6, with a specific enzymatic activity of 59.61 ± 0.00 U·mg-1 and a yield of around 39 %, with only one band observed in the SDS-PAGE electrophoresis analysis, indicating that the matrix produced can separate specific proteins from the total fraction in the raw material. The IMAC matrix immobilized with chlorophyll proved promising and viable for application in protease purification processes.

Characterization of coconut milk waste nanocellulose based curcumin-enriched Pickering nanoemulsion and its application in a blended beverage of defatted coconut milk and pineapple juice.

In this study, we aimed to develop a blended beverage enriched with curcumin. The curcumin was incorporated within a Pickering nanoemulsion that was stabilized with nanocellulose. The nanocellulose was synthesized from coconut milk waste residue using 38 %-42 % sulfuric acid (AC) and 5 and 10 min ultrasound (UL) separately and in combination (ACU). While combined treatment showed an increase in particle size with ultrasonication time, PDI was observed to decrease. ACU with 10 min ultrasonication was further used at 0.05 %, 0.1 %, 0.2 %, and 0.3 % for stabilization of curcumin enriched Pickering nanoemulsion. The curcumin in Pickering nanoemulsion fabricated with 0.1 % of nanocellulose with an average particle size and PDI value of 259.6 nm and 0.284, respectively was found to be the most stable as compared to other Pickering nanoemulsions at different pH levels and temperatures. RP-HPLC analysis revealed that with 0.1 % of nanocellulose, the Pickering nanoemulsion was most stable at 2 pH and 63 °C temperatures. The in vitro release of curcumin from Pickering nanoemulsion added to a blended beverage in intestinal phase was 51.58 %, which was higher than the stomach phase (38.19 %). The outcomes clearly showed Pickering nanoemulsion to be a promising carrier for curcumin encapsulation in beverage.

Effect of ultrasound combined with pineapple protease treatment on the tenderness of dried shrimp.

BACKGROUND: In order to improve the tenderness of dried shrimp products as well as to reduce the hardness of the meat during the drying process, shrimp were treated with ultrasound combined with pineapple protease and the tenderization condition was optimized by measuring the texture and shear force of dried shrimp. In addition, the sulfhydryl content, myofibril fragmentation index (MFI) and microstructure were also examined to clarify the mechanisms of shrimp tenderization. RESULTS: The results showed UB1 group with ultrasonic power of 100 W, heating temperature of 50 °C and pineapple protease concentration of 20 U mL-1 were the optimum tenderization conditions, where shrimp showed the lowest hardness (490.76 g) and shear force (2006.35 gf). Microstructure as well as sodium dodecyl sulfate-polyacrylamide gel electrophoresis results suggested that during the tenderization process the muscle segments of shrimps were broken, degradation of myofibrillar proteins occurred, and MFI values and total sulfhydryl content increased significantly (P < 0.05) (MFI value = 193.6 and total sulfhydryl content = 93.93 mmol mg-1 protein for UB 1 group). CONCLUSION: Ultrasound combined with bromelain could be used as a simple and effective tenderization method for the production of tender dried shrimp. The best conditions were 100 W ultrasonic power, 50 °C ultrasonic temperature, and 20 U mL-1 bromelain. © 2024 Society of Chemical Industry.

High surface area activated carbon from a pineapple (ananas comosus) crown via microwave-ZnCl2 activation for crystal violet and methylene blue dye removal: adsorption optimization and mechanism.

In this investigation, microwave irradiation assisted by ZnCl2 was used to transform pineapple crown (PN) waste into mesoporous activated carbon (PNAC). Complementary techniques were employed to examine the physicochemical characteristics of PNAC, including BET, FTIR, SEM-EDX, XRD, and pH at the point-of-zero-charge (pHpzc). PNAC is mesoporous adsorbent with a surface area of 1070 m2/g. The statistical optimization for the adsorption process of two model cationic dyes (methylene blue: MB and, crystal violet: CV) was conducted using the response surface methodology-Box-Behnken design (RSM-BBD). The parameters include solution pH (4-10), contact time (2-12) min, and PNAC dosage (0.02-0.1 g/100 mL). The Freundlich and Langmuir models adequately described the dye adsorption isotherm results for the MB and CV systems, whereas the pseudo-second order kinetic model accounted for the time dependent adsorption results. The maximum adsorption capacity (qmax) for PNAC with the two tested dyes are listed: 263.9 mg/g for CV and 274.8 mg/g for MB. The unique adsorption mechanism of MB and CV dyes by PNAC implicates multiple contributions to the adsorption process such as pore filling, electrostatic forces, H-bonding, and π-π interactions. This study illustrates the possibility of transforming PN into activated carbon (PNAC) with the potential to remove two cationic dyes from aqueous media.

The novelty of this research work stems from the conversion of pineapple (Ananas comosus) crown wastes with no monetary value into an efficient activated carbon adsorbent with relatively high surface area. Furthermore, a fast and convenient microwave assisted ZnCl₂ activation method was applied for producing the activated carbon (AC). The effectiveness of the produced AC was tested for the removal of two different cationic dyes: crystal violet (CV) and methylene blue (MB). A statistical optimization that employs a response surface methodology with the Box-Behnken design was employed to optimize the adsorption variables for the optimal dye removal. Moreover, the dye adsorption kinetics and thermodynamics, equilibrium isotherms, and the details of the adsorption process were reported herein.

Dark fermentation of pretreated hydrolysates of pineapple fruit waste for the production of biohydrogen using bacteria isolated from wastewater sources.

In the present study, both acidic and alkaline hydrolysate of pineapple waste was utilised for the production of biohydrogen using locally isolated bacterial strains. The bacteria were isolated from different wastewater sources and were identified as Proteus mirabilis, Pseudomonas aeruginosa, Bacillus altitudinus, Bacillus subtilis, Paenibacillus alvei, and Lysinibacillus sphaericus. Experimental results showed that the highest biohydrogen yield of 836.33 ± 48.02 mL H2 was produced from alkaline hydrolysate with Bacillus altitudinis during the 96thhr of fermentation. Among the different bacterial strains, B. altitudinis showed higher H2 production. Comparatively alkaline hydrolysates exhibited a higher yield of hydrogen than acidic hydrolysates. The final pH of the experiment was found to be in acidic range. The total VFA concentration ranged between 930 ± 207.85 mg/L to 3050 ± 476.97 mg/L. Both sugar degradation and COD reduction were more than 80% in the acidic and alkaline hydrolysates while the lowest sugar degradation and COD reduction were observed for the untreated biomass. The rationale behind this study was to convert the waste biomass into energy by utilising the potential of native bacterial communities.