Effect of ultrasound pre-treatment on the physicochemical composition of Agave durangensis leaves and potential enzyme production

Agave angustifolia Haw. Leaves as a Potential Source of Bioactive Compounds: Extraction Optimization and Extract Characterization

The leaves of Agave angustifolia Haw. are the main agro-waste generated by the mezcal industry and are becoming an important source of bioactive compounds, such as phenolic compounds, that could be used in the food and pharmaceutical industries. Therefore, the extraction and identification of these phytochemicals would revalorize these leaf by-products. Herein, maceration and supercritical carbon dioxide (scCO2) extractions were optimized to maximize the phenolic and flavonoid contents and the antioxidant capacity of vegetal extracts of A. angustifolia Haw. In the maceration process, the optimal extraction condition was a water-ethanol mixture (63:37% v/v), which yielded a total phenolic and flavonoid content of 27.92 ± 0.90 mg EAG/g DL and 12.85 ± 0.53 µg QE/g DL, respectively, and an antioxidant capacity of 32.67 ± 0.91 (ABTS assay), 17.30 ± 0.36 (DPPH assay), and 13.92 ± 0.78 (FRAP assay) µM TE/g DL. Using supercritical extraction, the optimal conditions for polyphenol recovery were 60 °C, 320 bar, and 10% v/v. It was also observed that lower proportions of cosolvent decreased the polyphenol extraction more than pressure and temperature. In both optimized extracts, a total of 29 glycosylated flavonoid derivatives were identified using LC-ESI-QTof/MS. In addition, another eight novel compounds were identified in the supercritical extracts, showing the efficiency of the cosolvent for recovering new flavonoid derivatives.

Phytochemical Profile and Composition of Chickpea (Cicer arietinum L.): Varietal Differences and Effect of Germination under Elicited Conditions

Germination is a simple process that improves the nutritional and medicinal values of seeds such as chickpeas. However, the detailed analysis of the phytochemical profile after chemical elicitation during chickpea germination is indispensable when making inferences about its biological properties. Therefore, an evaluation was made of the effect of the chemical inducers salicylic acid (SA, 1 and 2 mM), chitosan (CH, 3.3 and 7 μM), and hydrogen peroxide (H2O2, 20 and 30 mM) during germination at 25 °C with 70% RH for 4 days on the content of antinutritional and bioactive compounds, including phenolics, sterols, and saponins, in three Mexican chickpea varieties (Blanoro, Patron, and San Antonio) using UPLC-ELSD-ESI-QqQ-MS/MS, UPLC-DAD-ESI-QqQ-MS/MS, and HPLC-DAD-sQ-MS. The highest increase in phenolics and saponins was found in the Blanoro sprouts induced with SA 2 mM, whereas the highest phytosterol content was detected in San Antonio sprouts induced with CH 7 μM. In addition, significant increases in mono-, di-, and oligosaccharides and decreases in antinutritional contents were achieved after germination with most of the elicitation conditions. More importantly, we identified new compounds in chickpea sprouts, such as the lignans matairesinol and secoisolariciresinol, the phenolic compounds epicatechin gallate and methyl gallate, some phytosterols, and the saponin phaseoside 1, which further increased after chemical elicitation.

Recent advances on physical technologies for the pretreatment of food waste and lignocellulosic residues

The complete deployment of a bio-based economy is essential to meet the United Nations' Sustainable Development Goals from the 2030 Agenda. In this context, food waste and lignocellulosic residues are considered low-cost feedstocks for obtaining industrially attractive products through biological processes. The effective conversion of these raw materials is, however, still challenging, since they are recalcitrant to bioprocessing and must be first treated to alter their physicochemical properties and ease the accessibility to their structural components. Among the full pallet of pretreatments, physical methods are recognised to have a high potential to transform food waste and lignocellulosic residues. This review provides a critical discussion about the recent advances on milling, extrusion, ultrasound, and microwave pretreatments. Their mechanisms and modes of application are analysed and the main drawbacks and limitations for their use at an industrial scale are discussed.

Hunting Bioactive Molecules from the Agave Genus: An Update on Extraction and Biological Potential

Agaves are plants used in the production of alcoholic beverages and fibers. Ever since ancient times, pre-Hispanic cultures in Mexico have used them in traditional medicine to cure different ailments. Over the years, studies of the active principles responsible for the therapeutic benefits of agaves have increased. Leaves and fibers are the main agro-wastes generated in tequila and mezcal production, while fibers are the main waste product in the textile sector. Different investigations have referred to the agro-waste from agave processing as a source of bioactive molecules called secondary metabolites (SM). Among them, phenols, flavonoids, phytosterols, and saponins have been extracted, identified, and isolated from these plants. The role of these molecules in pest control and the prospect of metabolites with the biological potential to develop novel drugs for chronic and acute diseases represent new opportunities to add value to these agro-wastes. This review aims to update the biological activities and recent applications of the secondary metabolites of the genus Agave.

Agave By-Products: An Overview of Their Nutraceutical Value, Current Applications, and Processing Methods

Agave, commonly known as “maguey” is an important part of the Mexican tradition and economy, and is mainly used for the production of alcoholic beverages, such as tequila. Industrial exploitation generates by-products, including leaves, bagasse, and fibers, that can be re-valorized. Agave is composed of cellulose, hemicellulose, lignin, fructans, and pectin, as well as simple carbohydrates. Regarding functional properties, fructans content makes agave a potential source of prebiotics with the capability to lower blood glucose and enhance lipid homeostasis when it is incorporated as a prebiotic ingredient in cookies and granola bars. Agave also has phytochemicals, such as saponins and flavonoids, conferring anti-inflammatory, antioxidant, antimicrobial, and anticancer properties, among other benefits. Agave fibers are used for polymer-based composite reinforcement and elaboration, due to their thermo-mechanical properties. Agave bagasse is considered a promising biofuel feedstock, attributed to its high-water efficiency and biomass productivity, as well as its high carbohydrate content. The optimization of physical and chemical pretreatments, enzymatic saccharification and fermentation are key for biofuel production. Emerging technologies, such as ultrasound, can provide an alternative to current pretreatment processes. In conclusion, agaves are a rich source of by-products with a wide range of potential industrial applications, therefore novel processing methods are being explored for a sustainable re-valorization of these residues.

Advances in Valorization of Lignocellulosic Biomass towards Energy Generation

The booming demand for energy across the world, especially for petroleum-based fuels, has led to the search for a long-term solution as a perfect source of sustainable energy. Lignocellulosic biomass resolves this obstacle as it is a readily available, inexpensive, and renewable fuel source that fulfills the criteria of sustainability. Valorization of lignocellulosic biomass and its components into value-added products maximizes the energy output and promotes the approach of lignocellulosic biorefinery. However, disruption of the recalcitrant structure of lignocellulosic biomass (LCB) via pretreatment technologies is costly and power-/heat-consuming. Therefore, devising an effective pretreatment method is a challenge. Likewise, the thermochemical and biological lignocellulosic conversion poses problems of efficiency, operational costs, and energy consumption. The advent of integrated technologies would probably resolve this problem. However, it is yet to be explored how to make it applicable at a commercial scale. This article will concisely review basic concepts of lignocellulosic composition and the routes opted by them to produce bioenergy. Moreover, it will also discuss the pros and cons of the pretreatment and conversion methods of lignocellulosic biomass. This critical analysis will bring to light the solutions for efficient and cost-effective conversion of lignocellulosic biomass that would pave the way for the development of sustainable energy systems.

Chemical composition of Luffa aegyptiaca Mill., Agave durangensis Gentry and Pennisetum sp

The particleboard industry faces problems of wood shortage, which has led to the use of non-wood lignocellulosic materials. Furthermore, there is also interest in looking for materials that improve their physical and mechanical properties. The species Luffa aegyptiaca Mill. (fruit), Agave durangensis Gentry (bagasse) and Pennisetum sp. (plant, leaves and stem) could be used in the elaboration of wood-based particleboards. The aim of this study is to determine the feasibility of using these materials to produce particleboards in accordance with their chemical composition. Five materials were studied, A. durangensis (bagasse), L. aegyptiaca (fruit) and Pennisetum sp. (whole plant, leaves and stem). Extractives, holocellulose, Runkel lignin and ash content was determined. The pH of the fibers was also measured and a microanalysis of the ash was performed. ANOVA and Kruskal-Wallis tests were carried out, in addition Tukey and Dunn tests for group comparison were performed. Pennisetum sp. leaves presented the highest total extractives and ash content, while L. aegyptiaca fruit and A. durangensis bagasse had the highest both content of holocellulose and Runkel lignin respectively. The lowest pH was presented by the L. aegyptiaca fruit, while the highest was from the Pennisetum sp. stem. The element with the greatest presence in the five materials was potassium, except in A. durangensis bagasse showing calcium. L. aegyptiaca fruit has better characteristics to be used in particleboards with greater mechanical resistance because of its higher holocellulose content. However, Pennisetum sp. (plant, leaves and stem) could be used to make particleboards with high resistance to water absorption.

Utilization of Agave durangensis leaves by Bacillus cereus 4N for polyhydroxybutyrate (PHB) biosynthesis

Lignocellulosic wastes may provide a means to economize polyhydroxybutyrate (PHB) production. This study has proposed the use of Agave durangensis leaves obtained from the artisanal mezcal industry as a novel substrate for this aim. Results revealed an increase in PHB biosynthesis (0.32 g/L) and improvement in %PHB (16.79-19.51%) by Bacillus cereus 4N when A. durangensis leaves used as carbon source were physically pre-treated by ultrasound for 30 min (ADL + US30') and thermally pre-treated (ADL + Q). Chemical analyses and SEM studies revealed compositional and morphological changes when A. durangensis leaves were physically pre-treated. Also, elemental analysis of growth media showed that carbon/nitrogen ratios of 14-21, and low nitrogen, hydrogen, and protein content were well-suited for PHB biosynthesis. Confocal microscopy revealed morphological changes in the bacterial cell and carbonosome structure under the influence of different substrates. Finally, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) analyses showed that homopolymeric PHB with a high thermal-resistance (271.94-272.89 °C) was produced. Therefore, the present study demonstrates the potential use of physically pre-treated A. durangensis leaves to produce PHB. These results promote the development of a circular economy in Mexico, where lignocellulosic wastes can be employed to produce value-added biotechnological products.

Inactivation of Inulinase and Marination of High-Quality Jerusalem Artichoke (Helianthus tuberosus L.) Pickles With Screened Dominant Strains

Freshly harvested Jerusalem artichoke tubers contain inulinase, an enzyme that requires inactivation, because of its ability to hydrolysis inulin into fructose, which can be consumed by microorganism during marination. As the traditional pickling process takes 6 months, and involves the addition of a large amount of salt (18-20%), this production strategy is uneconomical and increases the nitrite intake. Additionally, miscellaneous bacteria produced during pickling affect the product taste. In this study, the enzyme inactivation effects of NaCl, NaHCO3, and ultrasound were evaluated. NaHCO3 treatment results in the highest degree of enzyme inactivation; however, the quality and flavor of the obtained Jerusalem artichoke pickles were not ideal. The Jerusalem artichoke pickles in which the enzymes were inactivated using a combination of NaCl and ultrasound exhibited better flavor than those exposed to NaHCO3; further, this combination reduced the inulinase activity of the Jerusalem artichokes to 2.50 U/mL, and maintained the inulin content at 61.22%. The strains LS3 and YS2, identified as Enterococcus faecalis and the salt-tolerant yeast Meyerozyma guilliermondii, respectively, were the dominant microorganisms isolated from the pickle juice. Jerusalem artichokes with inactivated inulinase were pickled with microbial powder, separated, purified, and dried to remove the natural Jerusalem artichoke sauce. This process shortened the fermentation cycle and improved product quality.