Pectin recovery and characterization from lemon juice waste streams

Exploiting residual cocoa biomass to extract advanced materials as building blocks for manufacturing nanoparticles aimed at alleviating formation-induced oxidative stress on human dermal fibroblasts

The global adoption of by-product valorisation processes aligns with the circular economy framework, ensuring sustainability in the agricultural sector. In cocoa production, residual biomass can offer the opportunity to extract advanced materials, contributing to nanotherapeutic solutions for biomedical applications. This study explores extraction processes for valorising cocoa pod husks (CPHs) and optimising valuable cocoa-derived biocompounds for enhanced health benefits. Various extraction processes are compared, revealing the significant influence of CPH powder amount and extraction time. Furthermore, metabolic analysis identifies 124 compounds in the metabolite mix, including tartaric acid, gluconic acid and bioactive agents with antioxidant properties, resulting in a high total phenolic content of 3.88 ± 0.06 mg g-1. Moreover, the extracted pectin, obtained through alkaline and enzymatic routes, shows comparable yields but exhibits superior antioxidant capacity compared to commercial pectin. The study progresses to using these extracted biocompounds to develop Layer-by-Layer multifunctionalised nanoparticles (LbL-MNPs). Physico-chemical characterisation via ζ-potential, FTIR-ATR, and XPS confirms the successful multilayer coating on mesoporous silica nanoparticles (MNPs). TEM analysis demonstrates a uniform and spherical nanoparticle morphology, with a size increase after coating. In vitro biological characterisation with neo-dermal human fibroblast cells reveals enhanced metabolic activity and biocompatibility of LbL-MNPs compared to bare MNPs. Also, the engineered nanoparticles demonstrate a protective effect against H2O2-induced intracellular oxidative stress on human dermal fibroblast cell lines, showcasing their potential as antioxidant carriers for biomedical applications.

Fractionation and characterisation of pectin-rich extracts from garlic biomass

Polysaccharides from garlic waste leaf and skin biomass have been isolated using a sequential extraction protocol and characterised using constituent sugar composition and linkage analysis, spectroscopy, chromatography and dilute solution viscometry. The results revealed that the isolated polysaccharides were predominantly pectins. The predominant monosaccharide in all samples was galacturonic acid (>61 %), followed by galactose and rhamnose. The pectins extracted from skin biomass were mainly homogalacturonan (83-91 %), whereas those extracted from leaf biomass comprised both homogalacturonan (62-65 %) and rhamnogalacturonan-I (35-38 %). The degree of methyl esterification of uronic acids in all samples was 44-56 %. The peak molecular weight of the main polysaccharide population in each sample was ∼ 350 x103 g/mol, with leaf extracts and the skin acidic extract containing a second, lower molecular weight peak. Overall, waste garlic biomass is a potential resource for commercial pectin extraction for use in food or pharmaceutical industries.

Effect of H2O2-assisted ultrasonic bath on the degradation and physicochemical properties of pectin

The effects of H2O2-assisted ultrasonic bath degradation technology on pectin were investigated. The degradation efficiency with different pectin concentrations, H2O2 concentrations, ultrasonic power, and ultrasonic time was analyzed. The results showed that pectin concentration was negatively correlated with the degradation efficiency of pectin, while, H2O2 concentration, ultrasonic power, and ultrasonic time were positive correlated with the degradation efficiency. Besides, the apparent viscosity and viscoelasticity of the degraded pectin decreased significantly. The antioxidant activity increased after the H2O2-assisted ultrasonic bath treatment. The results of FTIR, NMR, laser particle size, SEM, XRD, and AFM analysis indicated that the degradation treatment did not destroy the main structure of pectin. The average particle size and crystallinity of pectin decreased. The degree of aggregation and the height of the molecular chain decreased significantly. In conclusion, the H2O2-assisted ultrasonic bath degradation technique could effectively degrade pectin. This study provided a comprehensive analysis of the degradation of pectin under H2O2-assisted ultrasonic bath, which will be beneficial to further develop H2O2-assisted ultrasonic bath techniques for pectin degradation.

Towards Valorization of Food-Waste-Derived Pectin: Recent Advances on Their Characterization and Application

Pectin, a natural biopolymer, can be extracted from food waste biomass, adding value to raw materials. Currently, commercial pectin is mostly extracted from citrus peels (85.5%) and apple pomace (14.0%), with a small segment from sugar beet pulp (0.5%). However, driven by high market demand (expected to reach 2.12 billion by 2030), alternative agro-industrial waste is gaining attention as potential pectin sources. This review summarizes the recent advances in characterizing pectin from both conventional and emerging food waste sources. The focus is the chemical properties that affect their applications, such as the degree of esterification, the neutral sugars' composition, the molecular weight, the galacturonic acid content, and technological-functional properties. The review also highlights recent updates in nutraceutical and food applications, considering the potential use of pectin as an encapsulating agent for intestinal targeting, a sustainable biopolymer for food packaging, and a functional and emulsifying agent in low-calorie products. It is clear from the considered literature that further studies are needed concerning the complexity of the pectin structure extracted from emerging food waste raw materials, in order to elucidate their most suitable commercial application.

Extraction and characterization of pectin from watermelon rind using acetic acid

In this work, watermelon rind was used for extraction of pectin with acetic acid solution. The effects of pH, temperature and extraction time on the pectin yield were investigated. Response surface based on Box-Behnken model was employed to optimize the extraction parameters. The model shows an optimum pectin yield of 18.21%, which is in agreement with the value confirmed through experiment (18.20%). The moisture content, ash content, degree of esterification, degree of methylation, equivalent weight, methoxy content, and anhydrouronic acid of the extracted pectin were determined. The values of the moisture content, ash content, degree of esterification, degree of methylation, equivalent weight, methoxy content, anhydrouronic acid are 8.42%, 5.1%, 57.30%, 23.5%, 983.9 mg/mol, 7.3% and 72.36%, respectively. The results show watermelon peel can be an alternative source for pectin production with reasonable pectin yield and pectin quality.

Modulation of the Gut Microbiota Structure and Function by Two Structurally Different Lemon Pectins

Pectins are plant polysaccharides consumed as part of a diet containing fruits and vegetables. Inside the gastrointestinal tract, pectin cannot be metabolized by the mammalian cells but is fermented by the gut microbiota in the colon with the subsequent release of end products including short-chain fatty acids (SCFA). The prebiotic effects of pectin have been previously evaluated but reports are inconsistent, most likely due to differences in the pectin chemical structure which can vary by molecular weight (MW) and degree of esterification (DE). Here, the effects of two different MW lemon pectins with varying DEs on the gut microbiota of two donors were evaluated in vitro. The results demonstrated that low MW, high DE lemon pectin (LMW-HDE) altered community structure in a donor-dependent manner, whereas high MW, low DE lemon pectin (HMW-LDE) increased taxa within Lachnospiraceae in both donors. LMW-HDE and HMW-LDE lemon pectins both increased total SCFAs (1.49- and 1.46-fold, respectively) and increased acetic acid by 1.64-fold. Additionally, LMW-HDE lemon pectin led to an average 1.41-fold increase in butanoic acid. Together, these data provide valuable information linking chemical structure of pectin to its effect on the gut microbiota structure and function, which is important to understanding its prebiotic potential.

Valorization of citrus peel waste for the sustainable production of value-added products

Globally the generation and mismanagement of waste from fruit processing and post-harvest impose a severe burden on waste management strategies along with environmental pollution, health hazards. Citrus waste is one of such worrying fruit waste, which is rich in several value-added chemicals, including pectin. Pectin is a prebiotic polysaccharide possessing a multitude of health benefits. Citrus pectin has excellent gelling, thickening, water holding capacity, and encapsulating properties, which pave its functionality in versatile industrial fields including food processing and preservation, drug and therapeutic agents, cosmetics, and personal care products. The utilization of citrus wastes to derive valuable bioproducts can offer an effective approach towards sustainable waste management. With the ever-increasing demand, several strategies have been devised to increase the efficiency of pectin recovery from citrus waste. This review article discusses the sources, effect, and technology-mediated valorization of citrus waste, the functional and nutritive application of pectin along with its socio-economic and environmental perspective.

Short-time acoustic and hydrodynamic cavitation improves dispersibility and functionality of pectin-rich biopolymers from citrus waste

Pectin is a valuable biopolymer used as a natural, clean label additive for thickening and gelling. However, industry faces issues with dispersibility and stability of pectin formulations. To address these issues, the effect of short processing time (30-180 s) with hydrodynamic (HC) and acoustic cavitation (AC) on the dispersibility and gelling functionality of mandarin pectin-rich polysaccharide (M-PRP) was investigated. Short-time processing with HC and AC did not affect polymer composition. HC, but not AC, decreased polydispersity index (PDI) from 0.78 to 0.68 compared to the control. Electron and atomic force microscopy showed that HC and AC decreased aggregation of fibrous and matrix polymers. Both treatments increased apparent viscosity significantly from 0.059 Pa s to 0.30 Pa s at 10 ^-s. The pectin dispersions showed good gelling capacity upon addition of calcium (final conc. 35 mM). HC and AC treatments for 150 s led to gels that were 7 and 4 times stronger (as measured by peak force) than the control with more homogeneous, less porous structures. In conclusion, short-time HC and AC can improve the dispersibility and functionality of citrus pectin without affecting composition, and are promising technologies to facilitate the use of pectin in industry applications.

Use of near-infrared spectroscopy combined with chemometrics for authentication and traceability of intact lemon fruits

The reflectance NIR spectroscopy and chemometric data treatment on mature intact lemons, Limone di Sorrento PGI (cv Ovale di Sorrento) and Limone Costa D'Amalfi PGI (cv Sfusato Amalfitano) from Campania region, collected in 2018 and 2019, were used to predict properties, and discriminate cultivar and geographical provenance. By PCA, lemon NIR spectra grouped for production years due to the year variation of lemon properties attributable to annual climatic differences, homogeneous in all sites. This agrees with lemon chemical and physical differences by production year. Consequently, the relationship of NIR spectra with lemon quality properties by MLR and the cultivar and provenances discrimination by LDA were affected by year climatic difference; therefore, better model reliability was for single production year. NIR detectability of lemon properties did not appear beyond lemon thick peels, therefore the measured properties of lemon juices could derive from measurable properties of peel correlating with pulp properties.

Structure and rheology of pectic polysaccharides from baobab fruit and leaves

Linkage patterns and relaxation dynamics of baobab (Adansonia digitata) polysaccharides have been investigated by means of linkage analysis and rheometry. The fruit polysaccharide was mostly xylogalacturonan, with co-extracted α-glucan. The leaf polysaccharide consists predominantly of two domains, one branched at O-4 of the →2)-Rhap-(1→ residues and another branched at O-3 of the →4)-GalpA-(1→ backbone to single GlcpA-(1→ residues. Master curves of viscoelasticity of fruit polysaccharides manifested strong pH-dependency. At pH below the dissociation constant of galacturonic acid, dispersions showed liquid-like behaviour. In contrast, at neutral pH, a weak gel network formation was observed that destabilised rapidly under the influence of flow fields. The present work identifies xylogalacturonans from baobab fruit as polysaccharides with unique rheological characteristics that may point to new directions in food and pharmaceutical formulation.

The Second Life of Citrus Fruit Waste: A Valuable Source of Bioactive Compounds

Citrus fruits (CF) are among the most widely cultivated fruit crops throughout the world and their production is constantly increasing along with consumers' demand. Therefore, huge amounts of waste are annually generated through CF processing, causing high costs for their disposal, as well as environmental and human health damage, if inappropriately performed. According to the most recent indications of an economic, environmental and pharmaceutical nature, CF processing residues must be transformed from a waste to be disposed to a valuable resource to be reused. Based on a circular economy model, CF residues (i.e., seeds, exhausted peel, pressed pulp, secondary juice and leaves) have increasingly been re-evaluated to also obtain, but not limited to, valuable compounds to be employed in the food, packaging, cosmetic and pharmaceutical industries. However, the use of CF by-products is still limited because of their underestimated nutritional and economic value, hence more awareness and knowledge are needed to overcome traditional approaches for their disposal. This review summarizes recent evidence on the pharmacological potential of CF waste to support the switch towards a more environmentally sustainable society.

The primary, secondary, and structures of higher levels of pectin polysaccharides

Pectin is a heteropolysaccharide abundant in the cell wall of plants and is obtained mainly from fruit (citrus and apple), thus its properties are particularly prone to changes occurring during ripening process. Properties of pectin depend on the string-like structure (conformation, stiffness) of the molecules that determines their mutual interaction and with the surrounding environment. Therefore, in this review the primary, secondary, and structures of higher levels of pectin chains are discussed in relation to external factors including crosslinking mechanisms. The review shows that the primary structure of pectin is relatively well known, however, we still know little about the conformation and properties of the more realistic systems of higher orders involving side chains, functional groups, and complexes of pectin domains. In particular, there is lack of knowledge on the influence of postharvest changes and extraction method on the primary and secondary structure of pectin that would affect conformation in a given environment and assembly to higher structural levels. Exploring the above-mentioned issues will allow to improve our understanding of pectin functionality and will help to tailor new functionalities for the food industry based on natural but often biologically variable source. The review also demonstrates that atomic force microscopy is a very convenient and adequate tool for the evaluation of pectin conformation since it allows for the relatively straightforward stretching of the pectin molecule in order to measure the force-extension curve which is directly related to its stiffness or flexibility.