A hydrocolloid based biorefinery approach to the valorisation of mango peel waste

Extraction of cell wall pectins and hemicellulose from agro-industrial wastes: A sustainable alternative source

The efficient repurposing of agro-industrial waste has significantly enhanced the utilization of food resources. This study aims to propose a methodology for extracting cell wall polysaccharides from residues of mango (Mangifera indica), passion fruit (Passiflora edulis), and cashew (Anacardium occidentale). Polysaccharide fractions were obtained through sequential extraction protocols involving water, cyclohexane-trans-1,2-diamine tetracetate (CDTA), sodium carbonate:CDTA, and potassium hydroxide. These fractions were categorized as water-soluble pectin (WSP), CDTA-soluble pectin (CSP), sodium carbonate-soluble pectin (SSP), and hemicellulose (HC), respectively. Each polysaccharide fraction was characterized by Nuclear Magnetic Resonance (NMR) spectroscopy and Gel Permeation Chromatography (GPC). Monosaccharide composition was determined using Gas Chromatography-Mass Spectrometry (GC-MS). NMR spectra of WSP, CSP, and SSP fractions exhibited characteristic pectin features, while the HC fraction primarily comprised hemicellulose. Consequently, the proposed methodology demonstrates potential as a standardized protocol for the extraction of pectin and hemicellulose from various food sources.

Obtention and Characterization of Microcrystalline Cellulose from Industrial Melon Residues Following a Biorefinery Approach

Residual melon by-products were explored for the first time as a bioresource of microcrystalline cellulose (MCC) obtention. Two alkaline extraction methods were employed, the traditional (4.5% NaOH, 2 h, 80 °C) and a thermo-alkaline in the autoclave (2% NaOH, 1 h, 100 °C), obtaining a yield of MCC ranging from 4.76 to 9.15% and 2.32 to 3.29%, respectively. The final MCCs were characterized for their chemical groups by Fourier-transform infrared spectroscopy (FTIR), crystallinity with X-ray diffraction, and morphology analyzed by scanning electron microscope (SEM). FTIR spectra showed that the traditional protocol allows for a more effective hemicellulose and lignin removal from the melon residues than the thermo-alkaline process. The degree of crystallinity of MCC ranged from 51.51 to 61.94% and 54.80 to 55.07% for the thermo-alkaline and traditional processes, respectively. The peaks detected in X-ray diffraction patterns indicated the presence of Type I cellulose. SEM analysis revealed microcrystals with rough surfaces and great porosity, which could remark their high-water absorption capacity and drug-carrier capacities. Thus, these findings could respond to the need to valorize industrial melon by-products as raw materials for MCC obtention with potential applications as biodegradable materials.

Investigating the Water Relations in Aqueous Extract Powders of Mango (Mangifera indica) Peel and Seed Waste for Their Use in Food Matrices as a Value-Added By-Product

This study investigated the potential uses of discarded mango peel and seed parts by analyzing their water sorption behavior, hydration kinetics, and stability when converted into extract powders at pH 3 and 10. The results revealed that peel extracts had a higher water adsorption capacity compared with seed extracts due to differences in their composition. Peel extracts were primarily composed of carbohydrates (approximately 75%) with a low protein content, while seed extracts contained fewer carbohydrates (less than 30%) but higher levels of proteins (more than 30%) and lipids. The critical water content for maintaining the glassy state of peel extract powders during storage was found to be 0.025 and 0.032 g of water/g for extracts obtained at pH 3 and 10, respectively. In contrast, the Tg values of seed extracts remained relatively unchanged across different water content levels, suggesting that proteins and lipids inhibited the water's plasticizing effect in the solid matrix. These findings indicate that both mango waste fractions exhibit distinct hygroscopic behaviors, necessitating different approaches to processing and utilization. These extracts hold potential applications for various food products such as beverages, gels, sauces, or emulsions, contributing to the reduction in waste and the creation of value-added products from mango residues.

Mango Peel Nanofiltration Concentrates to Enhance Anaerobic Digestion of Slurry from Piglets Fed with Laminaria

The environmental impact of biowaste generated during animal production can be mitigated by applying a circular economy model: recycling, reinventing the life cycle of biowaste, and developing it for a new use. The aim of this study was to evaluate the effect of adding sugar concentrate solutions obtained from the nanofiltration of fruit biowaste (mango peel) to slurry from piglets fed with diets incorporating macroalgae on biogas production performance. The nanofiltration of ultrafiltration permeates from aqueous extracts of mango peel was carried out using membranes with a molecular weight cut-off of 130 Da until a volume concentration factor of 2.0 was reached. A slurry resulting from piglets fed with an alternative diet with the incorporation of 10% Laminaria was used as a substrate. Three different trials were performed sequentially: (i) a control trial (AD₀) with faeces resulting from a cereal and soybean-meal-based diet (S0); (ii) a trial with S₁ (10% L. digitata) (AD₁), and (iii) an AcoD trial to assess the effect of the addition of a co-substrate (20%) to S1 (80%). The trials were performed in a continuous-stirred tank reactor (CSTR) under mesophilic conditions (37.0 ± 0.4 °C), with a hydraulic retention time (HRT) of 13 days. The specific methane production (SMP) increased by 29% during the anaerobic co-digestion process. These results can support the design of alternative valorisation routes for these biowastes, contributing to sustainable development goals.

Sustainable approaches on industrial food wastes to value-added products - A review on extraction methods, characterizations, and its biomedical applications

The concept of zero waste discharge has been gaining importance in recent years towards attaining a sustainable environment. Fruit processing industries generate millions of tons of byproducts like fruit peels and seeds, and their disposal poses an environmental threat. The concept of extracting value-added bioactive compounds from bio-waste is an excellent opportunity to mitigate environmental issues. To date, significant research has been carried out on the extraction of essential biomolecules, particularly polysaccharides from waste generated by fruit processing industries. In this review article, we aim to summarize the different extraction methodologies, characterization methods, and biomedical applications of polysaccharides extracted from seeds and peels of different fruit sources. The review also focuses on the general scheme of extraction of polysaccharides from fruit waste with special emphasis on various methods used in extraction. Also, the various types of polysaccharides obtained from fruit processing industrial wastes are explained in consonance with the important techniques related to the structural elucidation of polysaccharides obtained from seed and peel waste. The use of seed polysaccharides as pharmaceutical excipients and the application of peel polysaccharides possessing biological activities are also elaborated.

Potential and prospects for utilization of avocado by-products in integrated biorefineries

The industrial processing of avocado to extract oil, and produce guacamole or sauces generates enormous quantities of peels and seeds (around 2 million tons worldwide in 2019) without commercially valuable applications. However, various studies have suggested the presence of a wide range of interesting compounds in the composition of these by-products. This review depicts a thorough outline of the capacity of avocado residues to be converted into a portfolio of commodities that can be employed in sectors such as the food, cosmetics, pharmaceuticals, environment, and energy industries. Therefore, a novel biorefinery strategy to valorize avocado-processing residues to obtain a polyphenolic extract, pectooligosaccharides, and succinic acid was presented. Additionally, the prospects and challenges facing a biorefinery based on the valorization of avocado residues are presented, particularly its techno-economic feasibility on an industrial scale, aiming for a resource-efficient circular bio-economy.

Standardization of ultrasound assisted extraction for the recovery of phenolic compounds from mango peels

Huge amount of mango peels is generated by the mango processing industries with rich composition of phenolic compounds having high antioxidant activity. In the present investigation, ultrasound assisted extraction was found to be an efficient extraction technique for recovery of phenolic compounds. The highest phenolic content was obtained using aqueous solution of ethanol (50%) over other extraction solvents. The highest phenolic content of 35.5 mg GAE/g was obtained using ultrasound assisted extraction method with solid to liquid ratio of 1:30 at 45 °C temperature, ultrasound amplitude 30% after 10 min of treatment time. The highest antioxidant activity of 92% was observed in the mango peels. The significant impact of ultrasonication treatment on the mango peels cell wall is evident from the scanning electron microscopy. The FTIR results indicated the rich composition of polyphenolic compounds present in the mango peels. Ultrasound assisted extraction can prove to be a sustainable green technique with high potential of bioactive compounds recovery like polyphenols for the valorization of mango by-products.

From mango by-product to food packaging: Pectin-phenolic antioxidant films from mango peels

The objective of the study was to prepare active films based on pectin and polyphenol-rich extracts from Tommy Atkins mango peels. Aqueous and methanolic extracts showed a variety of phenolic compounds that were identified by UPLC-MS analysis, and a high content of total phenolics that were quantified by the Folin-Ciocalteau method. The methanolic extract showed better results in antioxidant tests and was more effective in inhibiting the growth of Gram-positive and Gram-negative bacteria. The pectin extracted from mango peels showed good thermal stability and a degree of methoxylation of 58.3% by ¹H NMR. The films containing the phenolic extracts showed lower water vapor permeability when compared to the control film (without any phenolic extracts). The incorporation of the extracts led to an increase in elongation (ε) and a decrease in tensile strength (σ) and modulus of elasticity (Y). The films with aqueous or methanolic extracts showed higher antioxidant activity in terms of inhibition of the DPPH radical. Therefore, the films developed in this work are presented as a promising alternative for food packaging and/or coating applications.

Mango Peel Pectin: Recovery, Functionality and Sustainable Uses

Concerns regarding the overconsumption of natural resources has provoked the recovery of biopolymers from food processing biomass. Furthermore, the current market opportunity for pectin in other areas has increased, necessitating the search for alternative pectin resources. This is also a step towards the sustainable and circular green economy. Mango peel is the byproduct of agro-processing and has been used for high value-added components such as polysaccharide biopolymers. Pectin derived from the peel is yet to be exploited to its greatest extent, particularly in terms of its separation and physiochemical properties, which limit its applicability to dietary fiber in culinary applications. The functionality of the mango peel pectin (MPP) strongly depends on the molecular size and degree of esterification which highlight the importance of isolation and characterisation of pectin from this novel resource. This article therefore provides a useful overview of mango peel as a potential biomaterial for the recovery of MPP. Different extraction techniques and the integrated recovery were also discussed. The utilisation of MPP in different industrial schemes are also detailed out from different perspectives such as the pharmaceutical and biotechnology industries. This review convincingly expresses the significance of MPP, providing a sustainable opportunity for food and pharmaceutical development.

The Food-Materials Nexus: Next Generation Bioplastics and Advanced Materials from Agri-Food Residues

The most recent strategies available for upcycling agri-food losses and waste (FLW) into functional bioplastics and advanced materials are reviewed and the valorization of food residuals are put in perspective, adding to the water-food-energy nexus. Low value or underutilized biomass, biocolloids, water-soluble biopolymers, polymerizable monomers, and nutrients are introduced as feasible building blocks for biotechnological conversion into bioplastics. The latter are demonstrated for their incorporation in multifunctional packaging, biomedical devices, sensors, actuators, and energy conversion and storage devices, contributing to the valorization efforts within the future circular bioeconomy. Strategies are introduced to effectively synthesize, deconstruct and reassemble or engineer FLW-derived monomeric, polymeric, and colloidal building blocks. Multifunctional bioplastics are introduced considering the structural, chemical, physical as well as the accessibility of FLW precursors. Processing techniques are analyzed within the fields of polymer chemistry and physics. The prospects of FLW streams and biomass surplus, considering their availability, interactions with water and thermal stability, are critically discussed in a near-future scenario that is expected to lead to next-generation bioplastics and advanced materials.

Enzymatic Extraction and Characterization of Pectin from Cocoa Pod Husks (Theobroma cacao L.) Using Celluclast® 1.5 L

Cocoa pod husks are a waste generated during the processing of cocoa beans. We aimed to explore the enzymatic extraction of pectin using cellulases. The extraction process was optimized using a central composite design (CCD) and analyzed by response surface methodology (RSM). The parameters optimized were feedstock concentration (%), enzyme dosage (µL/g), and time (h). Three dependent variables were studied: pectin yield (g/100 g dry husk) (R2 = 97.02), galacturonic acid content (g/100 g pectin) (R2 = 96.90), and galacturonic acid yield (g/100 g feedstock) (R2 = 95.35). The optimal parameters were 6.0% feedstock concentration, 40 µL g-1 of enzyme, and 18.54 h, conditions that produced experimentally a pectin yield of 10.20 g/100 g feedstock, 52.06 g galacturonic acid/100 g pectin, and a yield 5.31 g galacturonic acid/100 g feedstock. Using the chemical extraction method, a yield of 8.08 g pectin/100 g feedstock and a galacturonic acid content of 60.97 g/100 g pectin were obtained. Using assisted sonication, a pectin yield of 8.28 g/100 g feedstock and a galacturonic acid content of 42.77 g/100 g pectin were obtained. Enzymatically optimized pectin has rheological and physicochemical features typical of this biomaterial, which provides an interesting alternative for the valorization of cocoa husks.

Environmentally Friendly Hydrothermal Processing of Melon by-Products for the Recovery of Bioactive Pectic-Oligosaccharides

Melon by-products, that currently lack high value-added applications, could be a sustainable source of bioactive compounds such as polysaccharides and antioxidants. In this work, melon peels were extracted with water to remove free sugars, and the water-insoluble solids (WISs) were subjected to hydrothermal processing. The effect of temperature on the composition of the obtained liquors and their total phenolic content was evaluated. The selected liquors were also characterized by matrix assisted laser desorption/ionization-time of flight mass spectroscopy (MALDI-TOF MS), fourier transform infrared spectroscopy (FTIR) and high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), and its phenolic compounds were identified and quantified by high-performance liquid chromatography-diode array detector-tandem mass spectrometry (HPLC-DAD-MS/MS). In addition, the spent solids from the hydrothermal treatment were characterized and their potential use was assessed. At the optimal conditions of 140 °C (severity 2.03), the total oligosaccharide yield accounted for 15.24 g/100 g WIS, of which 10.07 g/100 g WIS were oligogalacturonides. The structural characterization confirmed the presence of partially methyl esterified oligogalacturonides with a wide range of polymerization degrees. After precipitation, 16.59 g/100 g WIS of pectin were recovered, with a galacturonic acid content of 55.41% and high linearity.

Circular economy practices within energy and waste management sectors of India: A meta-analysis

Adoption of circular practices within environmental management is gaining worldwide recognition owing to rapid resource depletion and detrimental effects of climate change. The present study therefore attempted to ascertain the linkages between circular economy (CE) and sustainable development (SD) by examining the role of renewable energy (RE) and waste management (WM) sectors in CE combined with policy setup and enabling frameworks boosting the influx of circularity principles in the Indian context. Results revealed that research dedicated towards energy recovery from waste in India lacks integration with SD. Findings also revealed that although India is extremely dedicated towards attainment of the SDGs, penetration of CE principles within administration requires considerable efforts especially since WM regulations for municipal, plastic and e-waste lack alignment with CE principles. Integration of WM and RE policies under an umbrella CE policy would provide further impetus to the attainment of circularity and SD within the Indian economy.

Application of engineered yeast strain fermentation for oligogalacturonides production from pectin-rich waste biomass

Citrus wastes disposal is a problem faced by many juice plants due to high disposal costs. However, the citrus peel wastes (CPW) biomass, as bulk bioresources from the agro-industrial waste, is a good source of pectin. Present study aimed to utilize these CPW biomass by engineered yeast strain fermentation with an inexpensive method to produce oligogalacturonides (OGs). The results showed that the engineered yeast strain fermentation can produce significant amounts of OGs with the degree of polymerization ranged from 2 to 7 from the CPW bioresources. Under the optimized conditions using the response surface methodology, the best OGs yield were 26.1%. The present work is the first to use the engineered yeast strain for direct CPW biomass fermentation produced the OGs. We thereby paved a new way to utilize the pectin-rich bioresources.

Recent Trends in the Use of Pectin from Agro-Waste Residues as a Natural-Based Biopolymer for Food Packaging Applications

Regardless of the considerable progress in properties and versatility of synthetic polymers, their low biodegradability and lack of environmentally-friendly character remains a critical issue. Pectin is a natural-based polysaccharide contained in the cell walls of many plants allowing their growth and cell extension. This biopolymer can be extracted from plants and isolated as a bioplastic material with different applications, including food packaging. This review aims to present the latest research results regarding pectin, including the structure, different types, natural sources and potential use in several sectors, particularly in food packaging materials. Many researchers are currently working on a multitude of food and beverage industry applications related to pectin as well as combinations with other biopolymers to improve some key properties, such as antioxidant/antimicrobial performance and flexibility to obtain films. All these advances are covered in this review.

Process of fruit peel waste biorefinery: a case study of citrus waste biorefinery, its environmental impacts and recommendations

Fruit peels are a rich source of cellulose, hemicellulose, phenolic compounds, and terpenic compounds. Thus, they have the potential to be a novel renewable, sustainable, and low-cost raw material (source) for the production of several value-added products based on framework and concepts such as waste hierarchy that includes biofertilizers, dietary fiber, animal feed, industrial enzymes, substrate for the bioactive compounds production, synthesis of nanomaterials, and clean energy (from residual biomass). With a view of evaluating the environmental burden of biorefinery, a life cycle assessment (LCA) is performed for a representative citrus waste (CW) biorefinery. The functional unit used for LCA was set as 2500 kg of CW processed. The overall GWP was observed to be 937.3 kg CO₂ equivalent per 2500 kg of CW processed. On further analysis of the environmental impact, it was found that different steps contributed significantly, as shown by the various environmental indicator values. Alternative advanced process intensification technologies like microwave and ultrasound-assisted steps replacing the conventional steps when implemented show considerable reduction in environmental indicator values. The variations in the contribution to environmental indicators should be considered during the design and process selection of biorefineries.

Box-Behnken design based multi-objective optimisation of sequential extraction of pectin and anthocyanins from mango peels

Multi-objective sequential fractionation of mango (Mangifera indica L.) peels for pectin and anthocyanins in a biorefinery, was investigated with the aims of enhancing pectin purity, bioactivity and increasing recovered products. Anthocyanins were extracted from mango peels based on a Box-Behnken experimental design (ethanol concentration (50-80%), acetic acid concentration (0.1-2%), time (60-150 min) and temperature (25 °C)). The remaining residue was subsequently fractionated to recover pectin. The optimum anthocyanin conditions (67.45% ethanol, 0.24% acetic acid and 60 min) resulted in pectin with a 5.5% higher antioxidant activity, it was 23% richer in polygalacturonic acid (PGA) and had a yield of 31% w/w higher than conventionally extracted pectin. An anthocyanin extract with anthocyanin contents, polyphenol contents, and antioxidant activity of 22.33 mg/100 g, 132.62 mg/g, and 1.36 μg gallic acid equivalent, respectively, was obtained. Therefore, the sequential extraction of anthocyanins and pectin improves pectin functional properties and increases the mango peel value potential.

An integrated green biorefinery approach towards simultaneous recovery of pectin and polyphenols coupled with bioethanol production from waste pomegranate peels

An integrated biorefinery, incorporating hydrothermal processing of waste pomegranate peels (WPP), was proposed for the acid and organic solvent-free simultaneous recovery of pectin and phenolics with bioethanol production. The hydrothermal treatment (HT) was optimized using Box-Behnken design and the maximum recovery of pectin (18.8-20.9%) and phenolics (10.6-11.8%) were obtained by hydrothermal treatment at 115 °C for 40 min with a liquid-solid ratio of 10. The WPP pectin was characterized by IR, ¹H NMR, and TGA which showed close similarity to commercial pectin. Depending on WPP cultivar type the degree of esterification, galacturonic acid content and molecular weight of pectin were in the range of 68-74%, 71-72%, and 131,137-141,538 Da, respectively. The recovered phenolics contained 57-60% punicalagin. Enzyme digestibility of WPP improved using HT with 177 g glucose produced per kg dry mass which was fermented to obtain 80 g ethanol with 88% of theoretical yield.