Search Results (9)

The valorization of waste materials is essential for sustainability, with used cooking oils (UCOs) offering potential for transformation into valuable functional products. The study investigates the oxidative stability of sunflower and olive oils subjected to high temperatures (160–200 °C) and frying on their physico-chemical properties (acidity, peroxide and iodine value, total polar compounds). Significant deterioration occurred above 180 °C, with increased peroxide and polar compounds and reduced iodine values. A technological process for the purification and saponification of UCOs (sunflower, olive, and palm oils) was developed, demonstrating the potential to transform pollutant waste into a valuable and sustainable product—soap. The incorporation of oregano and thyme essential oils (EOs), identified by GC-FID as rich sources of carvacrol, thymol, p-cymene, and limonene, improved the functional properties of the soaps. The antimicrobial activity of soaps largely relates to their alkaline pH, while the incorporation of EOs contributes to additional antimicrobial effects, obtaining zones of inhibition of up to 10.8 mm against Staphylococcus aureus and up to 7.6 mm against Escherichia coli for palm oil. The study highlights a sustainable approach that transforms waste oils into functional soaps with EOs for added antimicrobial benefits. Full article

Avocado is a rich source of numerous nutrients, such as micro- and macroelements, essential unsaturated fatty acids, and vitamins essential for the correct functioning of the body. Consequently, its consumption has significantly increased in recent years. The primary edible part of the fruit is the flesh, while the seed is still considered biowaste. Currently, various methods for utilization of this biowaste are being explored, prompting the authors of this work to investigate the catalytic properties of ground avocado seeds. Dried, ground avocado seeds were used as the catalyst in the environmentally friendly oxidation of limonene with oxygen. The process was carried out in mild conditions, without the use of any solvent and at atmospheric pressure. The studies examined the influence of temperature (70–110 °C), the amount of the catalyst (0.5–5.0 wt%), and the reaction time (15–360 min). The analyses of the post-reaction mixtures were performed using the gas chromatography method (GC). The maximum value of the conversion of limonene obtained during the tests was 36 mol%. The main products of this process were as follows: 1,2-epoxylimonene, carveol, and perillyl alcohol. Also, the following compounds were determined in the post-reaction mixtures: carvone and 1,2-epoxylimonene diol. The studied process is interesting, taking into account both the management of waste in the form of avocado seeds and possible wide applications of limonene transformation products in medicine, cosmetics and the food industry. Given that limonene is now increasingly being extracted from waste orange peels, this is also a good way to manage the future naturally derived limonene and reduce the amount of waste orange peels. The presented studies fit perfectly with the goals of sustainable development and circular economy and may be the basis for the future development of “green technology” for obtaining value-added oxygenated derivatives of limonene. These studies show the use of waste biomass in the form of avocado seeds to obtain a green catalyst. In this context, our research presents an effective way of waste valorization. Full article

The fruits of Citrus limon are often purchased for their vitamin C-rich juice, while the fruit peel and the tree leaves are discarded as wastes. This study obtained the chemical profiles of the essential oils (EOs) of C. limon wastes (the peel and leaves), evaluated their medicinal value as antioxidants, their potential for sustainable use in agriculture as an insecticide for post-harvest preservation of grains, and their potential as a bioresource in livestock feed formulations. The EOs were isolated from C. limon leaves and peel using a hydro-distillation method on a Clevenger apparatus. The oil constituents were identified using the gas chromatography-mass spectrometry (GC-MS) hyphenated technique. The oils were evaluated for their in vitro antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power methods. An insecticidal study was conducted using contact toxicity, fumigation, and repellence bioassay methods against Sitophilus zeamais (maize weevils). Finally, the predicted income from using lemon peel as an alternative or substitute ingredient for maize in livestock feed formulations was obtained through a conventional simulation method. Chemically, limonene was found to be present in all the EOs analyzed (12–52%), while α-pinene was only found in the fresh leaf and peel oils (13.3% and 10.6%). Caryophyllene oxide was identified as the major component of the dried leaf oil (17.7%). At 20 µg m, the dry peel oil exhibited the highest inhibitory activity (52.41 ± 0.26%) against the DPPH radical, which was comparable to L-ascorbic acid (a standard antioxidant) at 54.25 ± 3.55%. The insecticidal study revealed that the dry peel oil is a better insect repellent (73.33 ± 6.95% at 10 µL) and fumigant (LC₅₀ = 0.17 µL g⁻¹ after 48 h) natural agent compared to the peel oil. Conversely, the dry peel oil showed a better contact activity (LC₅₀ = 1.69 µL g⁻¹) against the maize weevils compared to the dry leaf oil. The simulation study showed the cost of using dry lemon peel as an alternative to maize in livestock feed formulation to be ZAR 2.8 billion, compared against the higher cost of feed formulation with maize, which currently stands at ZAR 24.9 billion. This study has shown that C. limon wastes (the peel and leaves) contain EOs with unique chemical profiles, valuable medicinal properties as free radical scavengers, and considerable insecticidal properties for agricultural use in post-harvest grain preservation, presenting a cost-effective and promising bioresource for livestock feed production. Full article

The research aimed to determine the chemical composition, the antioxidant and anti-inflammatory activity as well as the antimicrobial activity against Gram-positive, Gram-negative and two fungal Candida ATCC strains of a commercial Boswellia essential oil (BEO) containing Boswellia carteri, Boswellia sacra, Boswellia papryfera, and Boswellia frereana. Additionally, molecular docking was carried out to show the molecular dynamics of the compounds identified from the essential oil against three bacterial protein targets and one fungal protein target. The major components identified by GC-MS (Gas Chromatography-Mass Spectrometry) were represented by α-pinene, followed by limonene. Evaluation of antioxidant activity using the DPPH (2,2-Diphenyl-1-Picrylhydrazyl) method showed high inhibition comparable to the synthetic antioxidant used as a control. Oxidative stability evaluation showed that BEO has the potential to inhibit primary and secondary oxidation products with almost the same efficacy as butylated hydroxyanisole (BHA). The use of BEO at a concentration of 500 ppm provided the best protection against secondary oxidation during 30 days of storage at room temperature, which was also evident in the peroxide value. Regarding the in vitro anti-inflammatory activity, the membrane lysis assay and the protein denaturation test revealed that even if the value of protection was lower than the value registered in the case of dexamethasone, the recommendation of using BEO as a protective agent stands, considering the lower side effects. Gram-positive bacteria proved more sensitive, while Pseudomonas aeruginosa presented different sensitivity, with higher MICs (minimal inhibitory concentration). Haemophilus influenzae demonstrated a MIC at 2% but with consecutive inhibitory values in a negative correlation with the increase in concentration, in contrast to E. coli, which demonstrated low inhibitory rates at high concentrations of BEO. The computational tools employed revealed interesting binding energies with compounds having low abundance. The interaction of these compounds and the proteins (tyrosyl-tRNA synthetase, DNA gyrase, peptide deformylase, 1,3-β-glucan synthase) predicts hydrogen bonds with amino acid residues, which are reported in the active sites of the proteins. Even so, compounds with low abundance in BEO could render the desired bioactive properties to the overall function of the oil sustained by physical factors such as storage and temperature. Interestingly, the findings from this study demonstrated the antioxidant and antimicrobial potential of Boswellia essential oil against food-related pathogens, thus making the oil a good candidate for usage in food, feed or food-safety-related products. Full article

Given the substantial world coffee production, tons of coffee fruit cascara rich in bioactive compounds are discarded annually. Using this by-product to produce potentially healthy and acceptable foods is a sustainable practice that aggregates value to coffee production and may help improve people’s lives. This study aimed to elaborate kombuchas from coffee cascara tea, evaluate their microbial profile, and monitor the changes in the volatile profile during fermentation, together with sensory attributes and acceptance by consumers from Rio de Janeiro (n = 113). Arabica coffee cascaras from Brazil and Nicaragua were used to make infusions, to which black tea kombucha, a Symbiotic Culture of Bacteria and Yeasts (SCOBY), and sucrose were added. Fermentation of plain black tea kombucha was also monitored for comparison. The volatile profile was analyzed after 0, 3, 6, and 9 days of fermentation via headspace solid phase microextraction GC-MS. A total of 81 compounds were identified considering all beverages, 59 in coffee cascara kombuchas and 59 in the black tea kombucha, with 37 common compounds for both. An increase mainly in acids and esters occurred during fermentation. Despite the similarity to black tea kombucha, some aldehydes, esters, alcohols, and ketones in coffee cascara kombucha were not identified in black tea kombucha. Potential impact compounds in CC were linalool, decanal, nonanal, octanal, dodecanal, ethanol, 2-ethylhexanol, ethyl acetate, ethyl butyrate, ethyl acetate, β-damascenone, γ-nonalactone, linalool oxide, phenylethyl alcohol, geranyl acetone, phenylacetaldehyde, isoamyl alcohol, acetic acid, octanoic acid, isovaleric acid, ethyl isobutyrate, ethyl hexanoate, and limonene. The mean acceptance scores for cascara kombuchas varied between 5.7 ± 0.53 and 7.4 ± 0.53 on a nine-point hedonic scale, with coffee cascara from three-day Nicaragua kombucha showing the highest score, associated with sweetness and berry, honey, woody, and herbal aromas and flavors. The present results indicate that coffee cascara is a promising by-product for elaboration of fermented beverages, exhibiting exotic and singular fingerprinting that can be explored for applications in the food industry. Full article

The discovery of heterogeneous catalysts synthesized in easy, sustainable ways for the valorization of olefins derived from renewable biomass is attractive from environmental, sustainability, and economic viewpoints. Here, an organic–inorganic hybrid catalyst formulated as [MoO₃(Hpto)]·H₂O (2), where Hpto = 5-(2-pyridyl-1-oxide)tetrazole, was prepared by a hydrolysis–condensation reaction of the complex [MoO₂Cl₂(Hpto)]∙THF (1). The characterization of 1 and 2 by FT-IR and Raman spectroscopies, as well as ¹³C solid-state NMR, suggests that the bidentate N,O-coordination of Hpto in 1 (forming a six-membered chelate ring, confirmed by X-ray crystallography) is maintained in 2, with the ligand coordinated to a molybdenum oxide substructure. Catalytic studies suggested that 2 is a rare case of a molybdenum oxide/organic hybrid that acts as a stable solid catalyst for olefin epoxidation with tert-butyl hydroperoxide. The catalyst was effective for converting biobased olefins, namely fatty acid methyl esters (methyl oleate, methyl linoleate, methyl linolenate, and methyl ricinoleate) and the terpene limonene, leading predominantly to the corresponding epoxide products with yields in the range of 85–100% after 24 h at 70 °C. The versatility of catalyst 2 was shown by its effectiveness for the oxidation of sulfides into sulfoxides and sulfones, at 35 °C (quantitative yield of sulfoxide plus sulfone, at 24 h; sulfone yields in the range of 77–86%). To the best of our knowledge, 2 is the first molybdenum catalyst reported for methyl linolenate epoxidation, and the first of the family [MoO₃(L)_x] studied for methyl ricinoleate epoxidation. Full article

Advances in technology have led to the production of sustainable antioxidants and natural monomers for food packaging and targeted drug delivery applications. Of particular importance is the synthesis of lignin polymers, and graft polymers, dopamine, and polydopamine, inulin, quercetin, limonene, and vitamins, due to their free radical scavenging ability, chemical potency, ideal functional groups for polymerization, abundance in the natural environment, ease of production, and activation of biological mechanisms such as the inhibition of the cellular activation of various signaling pathways, including NF-κB and MAPK. The radical oxygen species are responsible for oxidative damage and increased susceptibility to cancer, cardiovascular, degenerative musculoskeletal, and neurodegenerative conditions and diabetes; such biological mechanisms are inhibited by both synthetic and naturally occurring antioxidants. The orientation of macromolecules in the presence of the plasticizing agent increases the suitability of quercetin in food packaging, while the commercial viability of terpenes in the replacement of existing non-renewable polymers is reinforced by the recyclability of the precursors (thyme, cannabis, and lemon, orange, mandarin) and marginal ecological effect and antioxidant properties. Emerging antioxidant nanoparticle polymers have a broad range of applications in tumor-targeted drug delivery, food fortification, biodegradation of synthetic polymers, and antimicrobial treatment and corrosion inhibition. The aim of the review is to present state-of-the-art polymers with intrinsic antioxidant properties, including synthesis scavenging activity, potential applications, and future directions. This review is distinct from other works given that it integrates different advances in antioxidant polymer synthesis and applications such as inulin, quercetin polymers, their conjugates, antioxidant-graft-polysaccharides, and polymerization vitamins and essential oils. One of the most comprehensive reviews of antioxidant polymers was published by Cirillo and Iemma in 2012. Since then, significant progress has been made in improving the synthesis, techniques, properties, and applications. The review builds upon existing research by presenting new findings that were excluded from previous reviews. Full article

Monoterpenes are plant secondary metabolites, widely used in industrial processes as precursors of important aroma compounds, such as vanillin and (−)-menthol. However, the physicochemical properties of monoterpenes make difficult their conventional conversion into value-added aromas. Biocatalysis, either by using whole cells or enzymes, may overcome such drawbacks in terms of purity of the final product, ecological and economic constraints of the current catalysis processes or extraction from plant material. In particular, the ability of oxidative enzymes (e.g., oxygenases) to modify the monoterpene backbone, with high regio- and stereo-selectivity, is attractive for the production of “natural” aromas for the flavor and fragrances industries. We review the research efforts carried out in the molecular analysis of bacterial monoterpene catabolic pathways and biochemical characterization of the respective key oxidative enzymes, with particular focus on the most relevant precursors, β-pinene, limonene and β-myrcene. The presented overview of the current state of art demonstrates that the specialized enzymatic repertoires of monoterpene-catabolizing bacteria are expanding the toolbox towards the tailored and sustainable biotechnological production of values-added aroma compounds (e.g., isonovalal, α-terpineol, and carvone isomers) whose implementation must be supported by the current advances in systems biology and metabolic engineering approaches. Full article

The development of epoxy thermosets from renewable resources is of paramount importance in a sustainable development context. In this paper, a novel bio-based epoxy monomer derived from limonene was synthesized without epichlorohydrine and characterized. In fact, this paper depicts the synthesis of bis-limonene oxide (bis-LO). However, intern epoxy rings generally exhibit a poor reactivity and allow reaction with anhydride. Therefore, we used a reaction model with hexahydro-4-methylphthalic anhydride to compare reactivity of terminal and interepoxy functions. We also studied the influence of methyl group on intern epoxy functions. Furthermore, the influence of epoxy:anhydride stoichiometry and initiator amount was studied. These studies allow to propose an optimized formulation of bis-LO. Finally, a bis-LO-based thermoset was obtained and characterized. Full article