A chemical valorisation of melon peels towards functional food ingredients: Bioactives profile and antioxidant properties

Nutritional and Bioactive Profiling of Cucumis melo L. By-Products: Towards a Circular Food Economy

Food waste, due to the high quantities produced, becomes a significant environmental, economic, and social challenge worldwide. Simultaneously, the rising prevalence of chronic diseases has intensified the demand for healthier food options. A promising approach to address these issues involves the valorisation of food by-products for the development of innovative and healthier food products. Cucumis melo L., commonly consumed as a fruit, generates peels and seeds that are typically discarded. In the present study, the nutritional composition and antioxidant potential of pulp, peel, and seeds of C. melo L. (yellow and green melon) were comprehensively evaluated. The seeds were identified as a rich source of dietary fibre (39.0 and 39.7 g/100 g dw; p > 0.05) and protein (21.0 and 21.3 g/100 g dw; p > 0.05), exhibiting an appealing fatty acid profile. The peel contains high levels of dietary fibre (39.7 and 47.1 g/100 g dw; p > 0.05) and total phenolic compounds (1976 and 2212 mg GAE/100 g dw; p > 0.05), suggesting significant bioactive potential. The peels showed a high antioxidant capacity for both methods used, DPPH• (120 and 144 mg TE/100 g dw; p > 0.05) and FRAP (6146 and 7408 mg TE/100 g dw; p > 0.05) assays. Potassium emerged as the predominant mineral in the seeds (799 and 805 mg/100 dw; p > 0.05), while glutamic acid was the most abundant amino acid (4161 and 4327 mg/100 g dw; p > 0.05). These findings emphasise the antioxidant and nutritional properties of C. melo L. by-products, highlighting their potential for inclusion in novel food formulations. This study not only advances the understanding of C. melo L. properties but also supports the reduction of food waste and promotes sustainability within the food supply chain.

Inclusion of Pineapple By-Products as Natural Antioxidant Sources in Diets for European Sea Bass (Dicentrarchus labrax)

This study investigates the effects of pineapple by-products on feed preservation during storage at two different temperatures (25 °C and 4 °C) and on European sea bass (Dicentrarchus labrax) stress resistance. Four isoproteic, isolipidic, and isoenergetic diets were manufactured: CTRL-negative control, commercial diet without added antioxidants; VITE-positive control, CTRL diet with 100 mg kg-1 of vitamin E; and P2 and S2-VITE diet with 2% pineapple peel or stem flour, respectively. The fish (13.5 ± 0.8 g) were split into four replicate groups per diet and fed ad libitum for 12 weeks, after which they were subjected to a stress challenge of air exposure (1 min) followed by confinement (5 min, 100 kg m-3). Despite storage time lowering the antioxidant properties of all diets, P2 and S2 showed increased antioxidant capacity (DPPH•, ABTS•+, and ORAC) before and after storage. The diets were well accepted by the fish, and the VITE-fed fish showed significantly lower lipid peroxidation values in the liver and muscle compared to all remaining diets. However, pineapple by-product inclusion did not result in increased fish stress resistance. Further optimization is required for the successful use of pineapple by-products as natural antioxidants in aquafeeds.

Functional compounds in tropical fruit processing by-products and intrinsic factors affecting their composition: A review

Tropical fruits, highly demanded in the food industry, generate a considerable amount of waste during processing. These traditionally discarded by-products, such as peels, seeds and pomace, are rich in bioactive compounds, natural molecules that have beneficial properties for human health, as they participate in various metabolic processes in the organism. Among the most prominent compounds are flavonoids, carotenoids, phenolic compounds, tannins and vitamin C. Beyond their health benefits, these compounds have significant industrial value and are widely used in the textile, pharmaceutical, cosmetic, biotechnological and food fields, in the latter especially as preservatives, additives, colorants and others. This review explores the main bioactive compounds found in fruit by-products, highlighting their functional relevance and analyzing the intrinsic or fruit-derived factors that influence the composition of these compounds, such as the type of by-product (peels, seeds, bagasse, pomace), the variety of fruit, and the state of maturity at the time of processing. In addition, the extraction methods used to obtain these compounds are addressed, differentiating between conventional techniques, such as solvent extraction, and emerging methods, such as ultrasound-assisted extraction and supercritical fluid extraction, which offer advantages in terms of efficiency and sustainability. The diversity of bioactive compounds and their potential application in various industries highlight the importance of ongoing research in this field. It is necessary to further study the factors that influence the composition of these compounds, as well as the development of more efficient and sustainable extraction methods. These advances will not only add value to food industry waste, but will also contribute to the development of natural products with health benefits.

Valorisation of hop leaves for their bioactive compounds: Identification and quantification of phenolics across different varieties, crop years and stages of development

Hop leaves, a by-product from hop cone harvesting, contain phenolic compounds of potential value for food or beverage applications. However, the abundant phenolics in hop leaves remain largely unquantified. This study quantified phenolics in hop leaves over two crop years, for three commercially significant varieties, at different developmental stages post-flowering. Ethanolic hop extracts were characterised using LC-ESI-qTOF-MS/MS and HPLC-DAD for the annotation and quantification of phenolics and bitter resins. Hop leaf phenolic profile exhibited considerable structural diversity, differing significantly from that of respective cones. Kaempferol/quercetin 3-O-glycosides and chlorogenic acids were the most abundant sub-groups with phenolic acids, procyanidins, prenylflavonoids and bitter resins also present. Phenolic profile was mainly variety-dependent with some crop year and developmental effects. Flavonol 3-O-glycosides were the main compounds driving varietal differences. Findings demonstrate the structural diversity and high concentrations of phenolic compounds in hop leaf extracts and their potential as a source of bioactives for valorisation.

Bioactive Potential of Olive Leaf By-Product Throughout In Vitro Gastrointestinal Digestion

Olive leaf, an abundant and underutilized byproduct of the olive industry, has gained attention as a potential functional ingredient due to its high content of dietary fiber and phenolic compounds. However, little is known about its bioaccessibility and transformation throughout the digestive process, limiting its application in food formulations. This study provides a comprehensive and quantitative assessment of how ground olive leaf bioactive compounds behave during gastrointestinal digestion, offering new insights into their stability and potential health benefits. The total phenolics content and antioxidant activity of ground olive leaf increased in the oral and gastric phases, decreasing slightly in the intestinal phase, with a bioaccessibility of 46% and up to 70% for the total phenolic content and antioxidant activity, respectively. The principal individual phenolic compounds identified in the intestinal phase were oleuropein, luteolin-7-glycoside, luteolin-6-glycoside and ferulic acid, with bioaccessibilities of up to 97%. The main soluble sugars (fructose, glucose, and sucrose) and organic acids (succinic, citric, and acetic acids) detected in the olive leaf samples showed different behaviors during gastrointestinal digestion: sugars increased in the oral and gastric phases but decreased in the intestinal phase, with high bioaccessibility despite reduced recovery, while organic acids remained mostly stable, except for citric acid, which decreased significantly in the intestinal phase, all showing close to 100% bioaccessibility. These results provide the first detailed evidence of the digestive fate of ground olive leaf bioactive compounds, reinforcing its potential as a functional ingredient. Its natural availability, without requiring pre-treatment, combined with its high antioxidant potential and bioaccessibility, highlights its relevance for the development of innovative food ingredients, aligning with circular economy principles and sustainable food strategies.

Antimicrobial Properties of Fennel By-Product Extracts and Their Potential Applications in Meat Products

Background: Beef burgers are perishable meat products, and to extend their shelf life, EU Regulation 1129/11 permits the use of certain additives. Objectives: However, given the concerns of health-conscious consumers and the potential toxicity of synthetic substances, this study aimed to explore the use of fennel waste extracts as natural preservatives. Methods: This study characterized the bioactive compounds (phenolic content), the antioxidant activity (ABTS+ and DPPH assay), and the antimicrobial properties (against Salmonella enterica serotype Enteritidis, Escherichia coli, Staphylococcus aureus, Bacillus cereusi, and Pseudomonas aeruginosa) of different fennel waste extracts (LF, liquid fraction; SF, solid fraction and PF, pellet fraction). Additionally, the potential use of the best fennel extract was evaluated for its impact on beef burger shelf life (up to 18 days at 4 ± 1 °C) in terms of microbiological profile, pH, and activity water (aw). Results: The PF extract, which was rich in flavones, hydroxybenzoic, and hydroxycinnamic acids, demonstrated the highest antioxidant and antimicrobial activities. Microbiological analyses on beef burgers with PF identified this extract as a potential antimicrobial substance. The aw and pH values did not appear to be affected. Conclusions: In conclusion, fennel extracts could be proposed as natural compounds exploitable in beef burgers to preserve their quality and extend their shelf-life.

Phosphorous - Containing Activated Carbon Derived From Natural Honeydew Peel Powers Aqueous Supercapacitors

The introduction of phosphorous (P), and oxygen (O) heteroatoms in the natural honeydew chemical structure is one of the most effective, and practical approaches to synthesizing activated carbon for possible high-performance energy storage applications. The performance metrics of supercapacitors depend on surface functional groups and high-surface-area electrodes that can play a dominant role in areas that require high-power applications. Here, we report a phosphorous and oxygen co-doped honeydew peel-derived activated carbon (HDP-AC) electrode with low surface area for supercapacitor via H3PO4 activation. This activator forms phosphorylation with cellulose fibers in the HDP. The formation of heteroatoms stabilizes the cellulose structure by preventing the formation of levoglucosan (C6H10O5), a cellulose combustion product, which would otherwise offer a pathway for a substantial degradation of cellulose into volatile products. Therefore, heteroatom doping has proved effective, in improving the electrochemical properties of AC-based electrodes for supercapacitors. The specific capacitance of HDP-AC exhibits greatly improved performance with increasing carbon-to-H3PO4 ratio, especially in energy density and power density. The improved performance is attributed to the high phosphorous doping with a hierarchical porous structure, which enables the transportation of ions at higher current rates. The high specific capacitance of 486, and 478 F/g at 0.6, and 1.3 A/g in 1 M H2SO4 electrolyte with a prominent retention of 98.5 % is observed for 2 M H3PO4 having an impregnation ratio of 1 : 4. The higher yield of HDP-AC could only be obtained at an activation temperature of 500 °C with an optimized amount of H3PO4 ratio. The findings suggest that the concentration of heteroatoms as surface functional groups in the synthesized HDP-AC depends on the chosen biomass precursor and the processing conditions. This work opens new avenues for utilizing biomass-derived materials in energy storage, emphasizing the importance of sustainable practices in addressing environmental challenges and advancing toward a greener future.

Effect of ozone treatment on phenylpropanoid metabolism in harvested cantaloupes

Phenylpropanoid metabolism plays an important role in cantaloupe ripening and senescence, but the mechanism of ozone regulation on phenylpropanoid metabolism remains unclear. This study investigated how ozone treatment modulates the levels of secondary metabolites associated with phenylpropanoid metabolism, the related enzyme activities, and gene expression in cantaloupe. Treating cantaloupes with 15 mg/m3 of ozone after precooling can help maintain postharvest hardness. This treatment also enhances the production and accumulation of secondary metabolites, such as total phenols, flavonoids, and lignin. These metabolites are essential components of the phenylpropanoid metabolic pathway, activating enzymes like phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, 4CL, chalcone synthase, and chalcone isomerase. The results of the transcriptional expression patterns showed that differential gene expression related to phenylpropanoid metabolism in the peel of ozone-treated cantaloupes was primarily observed during the middle and late storage stages. In contrast, the pulp exhibited significant differential gene expression mainly during the early storage stage. Furthermore, it was observed that the level of gene expression in the peel was generally higher than that in the pulp. The correlation between the relative amount of gene changes in cantaloupe, activity of selected enzymes, and concentration of secondary metabolites could be accompanied by positive regulation of the phenylpropanoid metabolic pathway. Therefore, ozone stress induction positively enhances the biosynthesis of flavonoids in cantaloupes, leading to an increased accumulation of secondary metabolites. Additionally, it also improves the postharvest storage quality of cantaloupes.

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.

Impact of washing and freezing on nutritional composition, bioactive compounds, antioxidant activity and microstructure of mango peels

Mango peels are widely produced and highly perishable. Disinfectant washing and freezing are among the most used methods to preserve foods. However, their impact on products' properties is conditioned by the foods' features. This study evaluated for the first time the phytochemical composition, antioxidant activity, and microstructure of mango peels washed with peracetic acid (27 mg/mL for 19 min) and frozen at -20 °C for 30 days. Washing decreased the content of vitamin C (-7%), penta-O-galloyl-β-d-glucose (-23 %), catechin (-30 %), and lutein (-24 %), but the antioxidant activity was preserved. Freezing changed mango peels' microstructure, increased free phenolic compounds, namely acid gallic (+36 %) and catechin (+51 %), but reduced bound phenolic compounds (-12 % to -87 %), bound phenolic compounds' antioxidant activity (-51 % to -72 %), and violaxanthin (-51 %). Both methods were considered adequate to conserve mango peels since fiber and the main bioactive compounds (free mangiferin, free gallic acid, and β-carotene) remained unchanged or increased.

Alternative flours from pulp melons (Cucumis melo L.): Seasonality influence on physical, chemical, technological parameters, and utilization in bakery product

Fresh vegetables have high water content and low acidity, so drying can extend shelf life, allowing the obtaining of alternative flours for the development of new products. The study aimed to investigate the influence of the melon harvest and off-season on the chemical composition of melon (Cantaloupe, Charentais e Honey Dew) flours and the potential application in products. The flours were evaluated for granulometry, morphology, centesimal composition, lipid and mineral content, total phenolic compound (TPC), antioxidant activity, and technological properties. Cakes containing melon flour were produced to replace wheat flour (0, 25, and 50 %) and evaluated for proximate composition, microbiology, and sensory parameters. Flours were classified as fine-grained (MESH >16), except Charentais off-season (medium - MESH 8-16, and fine-grained - MESH >16), and all presented a rough surface and minimal cell wall ruptures. The harvest homogeneously influenced the humidity, as all the off-season flours showed higher levels [17-22 %] (p < 0.05) due to weather conditions. For TPC, Cantaloupe melon flours from the harvest (CFH) [208 mg/100 g] and off-season [877 mg/100 g] stood out (p < 0.05), and the latter showed greater antioxidant potential [328 μmol TE/g]. Palmitic, linoleic, and linolenic acid stood out in all flours, and potassium for minerals (63-78 %) in the harvest and off-season. The harvest and off-season specifically influenced the flour of each variety in swelling power, water solubility, oil absorption, and emulsifying capacity. For cakes with CFH, no thermotolerant coliforms and Escherichia coli were detected, and the mesophilic count was <1.0 CFU/g. The ash, protein, lipid, and fiber contents increased proportionally to melon flour addition (p < 0.05). Sensory acceptance was high for cakes containing 25 and 50 % of CFH [82.78 % and 82.53 %], and most consumers would likely buy the products (4.04 and 3.99) (p < 0.05). The study contributed to knowledge about the seasonality effect and demonstrated the potential use of melon flour in developing new products.

Natural Antioxidant Potential of Melon Peels for Fortified Foods

Agricultural and food waste recycling reduces natural resource losses, contributing significantly to the development of new green markets through the creation of redesigned products. In order to cycle valuable molecules, the peels from Italian cantaloupe (Cucumis melo L.) cultivars were studied and successfully characterized for high-added biomolecules to verify their possible exploitation as wealthy biomasses. Peels were investigated for their cell wall-modifying and browning enzymes, as well as for total polyphenols, ortho-diphenols, flavonoids, tannins, and antioxidant properties. The results of the analyses displayed great promise in one of the three cultivars investigated. Later on, a preliminary study using the best peel extract as a dietary supplement was carried out by preparing fortified seawater to enhance its antioxidant power. The effects of storage time (60 days) were examined at two temperatures through the determination of the stability of the polyphenol content. The kinetic parameters of degradation were also calculated. The "enriched sea water" retained great antioxidant activity in refrigerated conditions, demonstrating that there is good potential for melon by-products to add their natural compounds for food fortification. These findings may provide valuable data for scale-up, from the lab to the pilot or industrial application.

Enrichment of Cookies with Fruits and Their By-Products: Chemical Composition, Antioxidant Properties, and Sensory Changes

Cookies made from wheat have become increasingly popular as a snack due to their various advantages, such as their convenience as a ready-to-eat and easily storable food item, wide availability in different types, and affordability. Especially in recent years, there has been a trend towards enriching food with fruit additives, which increase the health-promoting properties of the products. The aim of this study was to examine current trends in fortifying cookies with fruits and their byproducts, with a particular focus on the changes in chemical composition, antioxidant properties, and sensory attributes. As indicated by the results of studies, the incorporation of powdered fruits and fruit byproducts into cookies helps to increase their fiber and mineral content. Most importantly, it significantly enhances the nutraceutical potential of the products by adding phenolic compounds with high antioxidant capacity. Enriching shortbread cookies is a challenge for both researchers and producers because the type of fruit additive and level of substitution can diversely affect sensory attributes of cookies such as color, texture, flavor, and taste, which have an impact on consumer acceptability.

Current progress in valorization of food processing waste and by-products for pectin extraction

Food processing waste and by-products such as peel of citrus fruit, melon, mango, pineapple, etc. and fruit pomace can be utilized for manufacturing of several high-value products. Valorization of these waste and by-products for extraction of pectin, can help offset growing environmental concerns, facilitate value-addition of by-products and their sustainable uses. Pectin has many applications in food industries such as gelling, thickening, stabilizing, and emulsifying agent, and as a dietary fibre. This review elaborates on various conventional and advanced, sustainable pectin extraction techniques, and paints a comparative picture between them considering extraction efficiency, quality, and functionality of the pectin. Conventional acid, alkali, and chelating agents-assisted extraction have been profusely used for pectin extraction, but advanced extraction technologies e.g., enzyme, microwave, supercritical water, ultrasonication, pulse electric field and high-pressure extraction are preferred due to less energy consumption, better quality product, higher yield, and minimal or no generation of harmful effluent.

Evolutionary Analysis of the Melon (Cucumis melo L.) GH3 Gene Family and Identification of GH3 Genes Related to Fruit Growth and Development

The indole-3-acetic acid (IAA) auxin is an important endogenous hormone that plays a key role in the regulation of plant growth and development. In recent years, with the progression of auxin-related research, the function of the Gretchen Hagen 3 (GH3) gene has become a prominent research topic. However, studies focusing on the characteristics and functions of melon GH3 family genes are still lacking. This study presents a systematic identification of melon GH3 gene family members based on genomic data. The evolution of melon GH3 family genes was systematically analyzed by means of bioinformatics, and the expression patterns of the GH3 family genes in different melon tissues during different fruit developmental stages and with various levels of 1-naphthaleneacetic acid (NAA) induction were analyzed with transcriptomics and RT-qPCR. The melon genome contains 10 GH3 genes distributed across seven chromosomes, and most of these genes are expressed in the plasma membrane. According to evolutionary analysis and the number of GH3 family genes, these genes can be divided into three subgroups, and they have been conserved throughout the evolution of melon. The melon GH3 gene has a wide range of expression patterns across distinct tissue types, with expression generally being higher in flowers and fruit. Through promoter analysis, we found that most cis-acting elements contained light- and IAA-responsive elements. Based on the RNA-seq and RT-qPCR analyses, it can be speculated that CmGH3-5, CmGH3-6 and CmGH3-7 may be involved in the process of melon fruit development. In conclusion, our findings suggest that the GH3 gene family plays an important role in the development of melon fruit. This study provides an important theoretical basis for further research on the function of the GH3 gene family and the molecular mechanism underlying the development of melon fruit.

A Review on the Potential Bioactive Components in Fruits and Vegetable Wastes as Value-Added Products in the Food Industry

The food production industry is a significant contributor to the generation of millions of tonnes of waste every day. With the increasing public concern about waste production, utilizing the waste generated from popular fruits and vegetables, which are rich in high-added-value compounds, has become a focal point. By efficiently utilizing food waste, such as waste from the fruit and vegetable industries, we can adopt a sustainable consumption and production pattern that aligns with the Sustainable Development Goals (SDGs). This paper provides an overview of the high-added-value compounds derived from fruit and vegetable waste and their sources. The inclusion of bioactive compounds with antioxidant, antimicrobial, and antibrowning properties can enhance the quality of materials due to the high phenolic content present in them. Waste materials such as peels, seeds, kernels, and pomace are also actively employed as adsorbents, natural colorants, indicators, and enzymes in the food industry. Therefore, this article compiles all consumer-applicable uses of fruit and vegetable waste into a single document.

Mining Candidate Genes Related to Heavy Metals in Mature Melon (Cucumis melo L.) Peel and Pulp Using WGCNA

The content of metal ions in fruits is inseparable from plant intake of trace elements and health effects in the human body. To understand metal ion content in the fruit and pericarp of melon (Cucumis melo L.) and the candidate genes responsible for controlling this process, we analyzed the metal ion content in distinct parts of melon fruit and pericarp and performed RNA-seq. The results showed that the content of metal ions in melon fruit tissue was significantly higher than that in the pericarp. Based on transcriptome expression profiling, we found that the fruit and pericarp contained elevated levels of DEGs. GO functional annotations included cell surface receptor signaling, signal transduction, organic substance metabolism, carbohydrate derivative binding, and hormone-mediated signaling pathways. KEGG pathways included pectate lyase, pentose and glucuronate interconversions, H⁺-transporting ATPase, oxidative phosphorylation, plant hormone signal transduction, and MAPK signaling pathways. We also analyzed the expression patterns of genes and transcription factors involved in hormone biosynthesis and signal transduction. Using weighted gene co-expression network analysis (WGCNA), a co-expression network was constructed to identify a specific module that was significantly correlated with the content of metal ions in melon, after which the gene expression in the module was measured. Connectivity and qRT–PCR identified five candidate melon genes, LOC103501427, LOC103501539, LOC103503694, LOC103504124, and LOC107990281, associated with metal ion content. This study provides a theoretical basis for further understanding the molecular mechanism of heavy metal ion content in melon fruit and peel and provides new genetic resources for the study of heavy metal ion content in plant tissues.

Myco-biorefinery approaches for food waste valorization: Present status and future prospects

Increases in population and urbanization leads to generation of a large amount of food waste (FW) and its effective waste management is a major concern. But putrescible nature and high moisture content is a major limiting factor for cost effective FW valorization. Bioconversion of FW for the production of value added products is an eco-friendly and economically viable strategy for addressing these issues. Targeting on production of multiple products will solve these issues to greater extent. This article provides an overview of bioconversion of FW to different value added products.

A Comparative Assessment on the Recovery of Pectin and Phenolic Fractions from Aqueous and DES Extracts Obtained from Melon Peels

This work evaluates the purification of melon peel extracts obtained by two eco-friendly methods: autohydrolysis and sodium acetate/urea/water extraction (1:3:1.6), an alkaline deep eutectic solvent (DES). For that, sequential ethanol precipitation and resin adsorption/desorption stages were proposed for the separate recovery of the pectic and phenolic fractions. In order to screen the optimal purification conditions, in a first step, the effect of ethanol concentrations (from 70 to 85%) on the precipitation of pectic oligosaccharides was assayed. Subsequently, the influence of the selected resin (Amberlite XAD4, XAD16HP and XAD7HP), liquid/resin ratios, and desorption sequences (varying ethanol concentrations and pH) on the phenolic compounds was also studied. The highest pectin yields were achieved with 85% ethanol: 16.11 and 18.05 g pectin/100 g water-insoluble solids (WIS) for autohydrolysis and DES extracts, respectively. All pectins presented a galacturonic acid content of about 45%, while autohydrolysis pectin presented a higher amount of neutral sugar side chains. The presence of low methoxyl GalA and both linear and branched OGalA with DP from 2 to 20 was also confirmed by FTIR and HPAEC-PAD analysis, respectively. Concerning the phenolic fraction, the resin adsorption and desorption steps at the selected conditions (XAD4 resin, liquid/resin ratio of 2 mL/g, eluted with 50% ethanol thrice) resulted in 79.55 and 4.08 mg GAE/g non-volatile content (NVC) for autohydrolysis and DES extracts, respectively, with improved antioxidant capacity. Moreover, some phenolic acids (protocatechuic and ferulic acids) and flavonoids (orientin, vitexin and naringenin) were quantified in the extracts by HPLC–PDA-MS/MS.

Comparative Analysis between Synthetic Vitamin E and Natural Antioxidant Sources from Tomato, Carrot and Coriander in Diets for Market-Sized Dicentrarchus labrax

Synthetic vitamin E is commonly used in aquafeeds to prevent oxidative stress in fish and delay feed and flesh oxidation during storage, but consumers’ preferences tend towards natural antioxidant sources. The potential of vegetable antioxidants-rich coproducts, dried tomato (TO), carrot (CA) and coriander (CO) was compared to that of synthetic vitamin E included in diets at either a regular (CTRL; 100 mg kg⁻¹) or reinforced dose (VITE; 500 mg kg⁻¹). Natural antioxidants were added at 2% to the CTRL. Mixes were then extruded and dried, generating five experimental diets that were fed to European sea bass juveniles (114 g) over 12 weeks. Vitamin E and carotenoid content of extruded diets showed signs of degradation. The experimental diets had very limited effects on fish growth or body composition, immunomodulatory response, muscle and liver antioxidant potential, organoleptic properties or consumer acceptance. Altogether, experimental findings suggest that neither a heightened inclusion dose of 500 mg kg⁻¹ of vitamin E, nor a 2% inclusion of natural antioxidants provided additional antioxidant protection, compared to fish fed diets including the regular dose of 100 mg kg⁻¹ of vitamin E.

Identification and Pathogenicity of Fungi Associated with Leaf Spot of Muskmelon in Eastern Shandong Province, China

Leaf spot is a serious disease in the growth and development of muskmelon, which can affect its quality and yield. Over the past years, Malianzhuang Muskmelon Base, the main muskmelon producing area in Shandong Province, China, has been seriously affected by leaf spot. Since 2018, symptomatic leaves were collected from 11 production areas of this base to determine the pathogens of muskmelon foliar diseases. Two-hundred fungal strains were isolated and 10 genera and 17 species were identified based on morphological characteristics and multilocus phylogenetic analysis (ITS, GADPH, RPB2, HIS3, EF-1α, and LSU). The most frequently isolated species from each sampling area was Alternaria tenuissima with 77 strains, followed by A. alternata. Pathogenicity experiments showed that A. alternata, A. tenuissima, Fusarium neocosmosporiellum (formerly Neocosmospora vasinfecta), F. acuminatum, Exserohilum rostratum, Bipolaris sorokiniana, and Stagonosporopsis cucurbitacearum (formerly Didymella bryoniae) could cause symptoms highly similar to those of infected leaves observed under natural conditions in the field. Therefore, these fungal isolates are considered to be the primary pathogens causing muskmelon leaf spot, and A. tenuissima and A. alternata were the most common and virulent pathogens in this study. In addition, this is the first study of F. neocosmosporiellum, F. acuminatum, E. rostratum, and B. sorokiniana as pathogens associated to muskmelon leaf spot in China as well as the world.

Valorisation of food agro-industrial by-products: From the past to the present and perspectives

Food agro-industrial by-products mainly include peels, seeds, stems, bagasse, kernels, and husk, derived during food processing. Due to their overproduction and the lack of sustainable management, such by-products have been conventionally rejected and wasted in landfills, being the principal strategy for their treatment, but nowadays, this strategy has been associated with several environmental, social and economic issues. Hence, we focused on the use of different consolidated biotechnological processes and methodologies as suitable strategies for food by-products management and valorisation, highlighting them as potential bioresources because they still gather high compositional and nutritional value, owing to their richness in functional and bioactive molecules with human health benefits. Food by-products could be utilised for the development of new food ingredients or products for human consumption, promoting their integral valorisation and reincorporation to the food supply chain within the circular bioeconomy concept, creating revenue streams, business and job opportunities. In this review, the main goal was to provide a general overview of the food agro-industrial by-products utilised throughout the years, improving global sustainability and human nutrition, emphasising the importance of biowaste valorisation as well as the methodologies employed for the recovery of value-added molecules.

Impact of Processing Approach and Storage Time on Bioactive and Biological Properties of Rocket, Spinach and Watercress Byproducts

The high nutritional value of vegetables is well recognized, but their short shelf life and seasonal nature result in massive losses and wastes. Vegetable's byproducts are an opportunity to develop value-added ingredients, increasing food system efficiency and environmental sustainability. In the present work, pulps and powders of byproducts from rocket and spinach leaves and watercress were developed and stored for six months under freezing and vacuum conditions, respectively. After processing and storage, microbiological quality, bioactive compounds (polyphenols, carotenoids and tocopherols profiles), antioxidant capacity, and pulps viscosity were analyzed. Generally, the developed vegetable's pulps and powders were considered microbiologically safe. Although some variations after processing and storage were verified, the antioxidant activity was preserved or improved. A rich phenolic composition was also registered and maintained. During freezing, the quantitative carotenoid profile was significantly improved (mainly in rocket and spinach), while after drying, there was a significant decrease. A positive effect was verified in the vitamin E level. Both processing and storage conditions resulted in products with relevant phenolics, carotenoids and tocopherol levels, contributing to the antioxidant activity registered. Thus, this study demonstrates the potential of vegetable byproducts valorization through developing these functional ingredients bringing economic and environmental value into the food chain.

The Arbuscular Mycorrhizal Fungus Rhizophagus irregularis MUCL 41833 Modulates Metabolites Production of Anchusa officinalis L. Under Semi-Hydroponic Cultivation

Anchusa officinalis is recognized for its therapeutic properties, which are attributed to the production of different metabolites. This plant interacts with various microorganisms, including the root symbiotic arbuscular mycorrhizal fungi (AMF). Whether these fungi play a role in the metabolism of A. officinalis is unknown. In the present study, two independent experiments, associating A. officinalis with the AMF Rhizophagus irregularis MUCL 41833, were conducted in a semi-hydroponic (S-H) cultivation system. The experiments were intended to investigate the primary and secondary metabolites (PMs and SMs, respectively) content of shoots, roots, and exudates of mycorrhized (M) and non-mycorrhized (NM) plants grown 9 (Exp. 1) or 30 (Exp. 2) days in the S-H cultivation system. Differences in the PMs and SMs were evaluated by an untargeted ultrahigh-performance liquid chromatography high-resolution mass spectrometry metabolomics approach combined with multivariate data analysis. Differences in metabolite production were shown in Exp. 1. Volcano-plots analysis revealed a strong upregulation of 10 PMs and 23 SMs. Conversely, in Exp. 2, no significant differences in PMs and SMs were found in shoots or roots between M and NM plants whereas the coumarin scoparone and the furanocoumarin byakangelicin, accumulated in the exudates of the M plants. In Exp. 1, we noticed an enhanced production of PMs, including organic acids and amino acids, with the potential to act as precursors of other amino acids and as building blocks for the production of macromolecules. Similarly, SMs production was significantly affected in Exp 1. In particular, the phenolic compounds derived from the phenylpropanoid pathway. Fifteen di-, tri-, and tetra-meric C₆-C₃ derivatives of caffeic acid were induced mainly in the roots of M plants, while four oleanane-types saponins were accumulated in the shoots of M plants. Two new salvianolic acid B derivatives and one new rosmarinic acid derivative, all presenting a common substitution pattern (methylation at C-9"' and C-9' and hydroxylation at C-8), were detected in the roots of M plants. The accumulation of diverse compounds observed in colonized plants suggested that AMF have the potential to affect specific plant biosynthetic pathways.

Development of Frozen Pulps and Powders from Carrot and Tomato by-Products: Impact of Processing and Storage Time on Bioactive and Biological Properties

Vegetables and fruits have an interesting nutritional profile, rich in bioactive metabolites, holding a high antioxidant potential and health associated benefits. However, their functional properties, the shorter shelf-life due to their high-water content, and their seasonality nature lead to extensive food losses and waste. The valorization of vegetables and fruits by-products through the development of value-added products and the application of preservation methods is of utmost importance to prevent food losses and waste. In this study, based on a circular economy approach, pulps and powders of baby carrot and cherry tomato by-products were prepared. Freezing, hot air drying and storage time impact on antioxidant activity and bioactive compounds were studied. Microbiological quality and pulps viscosity were also monitored for 6 months. During the freezing storage, TPC and antioxidant capacity by ABTS and ORAC assays decreased. The antioxidant capacity by DPPH method and carotenoid content increased during the first months of freezing, but then decreased. The drying process negatively affected the antioxidant capacity as well as carotenoid and polyphenolic content compared with the fresh vegetables. Both processing methodologies positively impacted the vitamin E content. During drying storage, there were no key variations in antioxidant capacity and bioactive content.

Impact of Extraction Process in Non-Compliant ‘Bravo de Esmolfe’ Apples towards the Development of Natural Antioxidant Extracts

The ‘Bravo de Esmolfe’ apple (BE) is rich in antioxidants and represents one of the most important traditional cultivars in Portugal. A large amount of non-compliant BE, with no market value, it is generated every year. Thus, an effort to find value-added solutions is of utmost importance. For the first time, green extraction (microwave-assisted-extraction (MAE) and ultrasound-assisted-extraction (UAE)) were compared against conventional extraction (with (CET) and without temperature (CE)) to select the most efficient process to produce a natural antioxidant extract from non-compliant BE. The results showed that MAE and CET are good methodologies for developing a BE antioxidant extract. However, MAE is more sustainable than CET, requiring less time to reach high temperatures. The MAE-extract showed great antioxidant activity (14.80 ± 0.70 mg TE/g DE by ORAC, 3.92 ± 0.25 mg AAE/g DE by ABTS, and 5.11 ± 0.13 mg TE/g DE by DPPH). This extract revealed high amount of chlorogenic acid (0.48 ± 0.07 mg/g DE), (−)-epicatechin (0.30 ± 0.02 mg/g DE) and phloridzin (0.13 ± 0.01 mg/g DE). This study shows that non-compliant BE is a useful source of antioxidants, being a sustainable way for the recovery of value-added compounds from the rejected fruit in line with sustainable and circular bioeconomy principles.

Valorisation of Olea europaea L. Olive Leaves through the Evaluation of Their Extracts: Antioxidant and Antimicrobial Activity

Olea europaea L. leaves constitute a source of bioactive compounds with recognized benefits for both human health and technological purposes. In the present work, different extracts from olive leaves were obtained by the application of two extraction methods, Soxhlet and microwave-assisted extraction (MAE), and six solvents (distilled water, ethanolic and glycerol mixtures solvents). MAE was applied under 40, 60 and 80 °C for 3, 6.5 and 10 min. The effect of the extraction method, solvent and treatment factors (the latter in MAE) on the total phenol content (TPC), the antioxidant activity (AA) and the phenolic profile of the extracts were all evaluated. The extracts showed high values of TPC (up to 76.1 mg GAE/g DW) and AA (up to 78 mg TE/g DW), with oleuropein being the most predominant compound in all extracts. The Soxhlet extraction method exhibited better yields in TPC than in MAE, although both methods presented comparable AA values. The water MAE extract presented the strongest antimicrobial activity against five foodborne pathogens, with minimum inhibitory concentration (MIC) values ranging from 2.5 to 60 mg/mL. MAE water extract is proposed to be exploited in the food and nutraceutical industry in the frame of a sustainable economy.