An optimal control approach to steam distillation of essential oils from aromatic plants

Pre- and Postharvest Strategies for Pleurotus ostreatus Mushroom in a Circular Economy Approach

Mushroom cultivation presents a viable solution for utilizing agro-industrial byproducts as substrates for growth. This process enables the transformation of low-economic-value waste into nutritional foods. Enhancing the yield and quality of preharvest edible mushrooms, along with effectively preserving postharvest mushrooms, stands as a significant challenge in advancing the industry. Implementing pre- and postharvest strategies for Pleurotus ostreatus (Jacq.) P. Kumm (oyster mushroom) within a circular economy framework involves optimizing resource use, minimizing waste, and creating a sustainable and environmentally friendly production system. This review aimed to analyze the development and innovation of the different themes and trends by bibliometric analysis with a critical literature review. Furthermore, this review outlines the cultivation techniques for Pleurotus ostreatus, encompassing preharvest steps such as spawn production, substrate preparation, and the entire mushroom growth process, which includes substrate colonization, fruiting, harvesting, and, finally, the postharvest. While novel methodologies are being explored for maintaining quality and extending shelf-life, the evaluation of the environmental impact of the entire mushroom production to identify areas for improvement is needed. By integrating this knowledge, strategies can be developed for a more sustainable and circular approach to Pleurotus ostreatus mushroom cultivation, promoting environmental stewardship and long-term viability in this industry.

The Extraction and Impact of Essential Oils on Bioactive Films and Food Preservation, with Emphasis on Antioxidant and Antibacterial Activities-A Review

Essential oils, consisting of volatile compounds, are derived from various plant parts and possess antibacterial and antioxidant properties. Certain essential oils are utilized for medicinal purposes and can serve as natural preservatives in food products, replacing synthetic ones. This review describes how essential oils can promote the performance of bioactive films and preserve food through their antioxidant and antibacterial properties. Further, this article emphasizes the antibacterial efficacy of essential oil composite films for food preservation and analyzes their manufacturing processes. These films could be an attractive delivery strategy for improving phenolic stability in foods and the shelf-life of consumable food items. Moreover, this article presents an overview of current knowledge of the extraction of essential oils, their effects on bioactive films and food preservation, as well as the benefits and drawbacks of using them to preserve food products.

Chios Mastic Gum: Chemical Profile and Pharmacological Properties in Inflammatory Bowel Disease: From the Past to the Future

Chios mastic gum, the product of the tree Pistacia lentiscus var. Chia, has been used for more than 2500 years in traditional Greek medicine for treating several diseases, thanks to the anti-inflammatory and antioxidant properties of its components. Despite the long-time use of mastic in gastroenterology and in particular in chronic-inflammation-associated diseases, to date, the literature lacks reviews regarding this topic. The aim of the present work is to summarize available data on the effects of P. lentiscus on inflammatory bowel disease. A comprehensive review of this topic could drive researchers to conduct future studies aimed at deeply investigating P. lentiscus effects and hypothesizing a mechanism of action. The present review, indeed, schematizes the possible bioactive components of mastic gum. Particular care is given to P. lentiscus var. Chia medicaments' and supplements' chemical compositions and their pharmacological action in inflammatory bowel disease.

Supercritical CO2 as a Valuable Tool for Aroma Technology

This review addresses the possibilities of using supercritical carbon dioxide (SC-CO₂) in the flavor industry in extraction and fractionation processes and its use as a reaction medium to generate aroma esters. The advantages and disadvantages are presented, comparing SC-CO₂ processing with traditional methods. The most distinguishable features of SC-CO₂ include mild reaction conditions, time savings, fewer toxicity concerns, higher sustainability, and the possibility of modulating solvent selectivity according to the process conditions (such as pressure and temperature). Thus, this review indicates the potential of using SC-CO₂ to obtain a high selectivity of compounds that can be applied in aroma technology and related fields.

Coacervation as a Novel Method of Microencapsulation of Essential Oils-A Review

These days, consumers are increasingly "nutritionally aware". The trend of "clean label" is gaining momentum. Synthetic additives and preservatives, as well as natural ones, bearing the E symbol are more often perceived negatively. For this reason, substances of natural origin are sought tfor replacing them. Essential oils can be such substances. However, the wider use of essential oils in the food industry is severely limited. This is because these substances are highly sensitive to light, oxygen, and temperature. This creates problems with their processing and storage. In addition, they have a strong smell and taste, which makes them unacceptable when added to the product. The solution to this situation seems to be microencapsulation through complex coacervation. To reduce the loss of essential oils and the undesirable chemical changes that may occur during their spray drying-the most commonly used method-complex coacervation seems to be an interesting alternative. This article collects information on the limitations of the use of essential oils in food and proposes a solution through complex coacervation with plant proteins and chia mucilage.

The Preparation of the Essential Oil from Pomelo (Citrus maxima ‘Shatian Yu’) Peel Using Microwave-Assisted Distillation by Pectinase Soaking and Its Anti-Fungal Activity

To verify the anti-fungus properties of the crop-harmful pseudocercospora, the essential oil (EO) of pomelo peel (PP) was extracted by a single factor combined with response surface optimization. Meanwhile, the composition and activity of EO were studied. The PP was squeezed by a screw extruder and pretreatmented by pectinase, then extracted by microwave-assisted steam distillation. The optimal conditions were as follows: pectinase dosage was 69.17 μmol/g, microwave power was 651.42 W and extraction time was 43.84 min. The dry weight (DW) yield of PPEO reached 14.63 mL/kg DW after BBD optimization. There were 23 compounds in the PPEO identified by GC-MS. Limonene, α-phrenbutene, and laurene in PPEO accounted for 79.31%, 4.72%, and 3.46%, respectively. In addition, the antifungal was effective when the concentration of PPEO was 3.5 mg/mL. Therefore, this study has guiding significance for the development of natural resources.

Pilot-Scale Evaluation of Concentrating Solar Thermal Technology for Essential Oil Extraction and Comparison with Conventional Heating Sources for Use in Agro-Based Industrial Applications

The conventional steam-distillation method requires a high amount of saturated steam and as a result, a lot of energy. Besides being energy-intensive, conventional steam-distillation processes emit carbon dioxide into the atmosphere. The energy demand in essential oils processing and related agro-based processes can be alleviated by using concentrating solar thermal (CST) technologies. Most of the solar plants installed in South Africa use flat plate collectors and evacuated tube collector systems with temperatures below 100 °C, which is ideal for only a low-temperature process application. This paper investigates the use of a low-cost CST technology, the parabolic trough collector (PTC), for steam-distillation in an extraction process. The PTC-powered system was built and tested for extracting essential oil from citrus peels. For comparison, the extraction process was carried out on a laboratory scale, a pilot gas-powered system, and PTC. Essential oil yields for orange, lemon, and mandarin were 0.65, 0.44, and 1.17%, respectively, using gas-powered steam-distillation. The yields for PTC were 0.67, 0.53, and 1.09%, which were all within the expected ranges. Gas chromatography results for the PTC experiment showed the presence of key components such as limonene (90%) in the essential oils. The PTC achieved a significant overall system efficiency of 54.99%, even though some parts of the device were not thermally insulated. The results showed that PTC can compete with gas-powered systems. Furthermore, the essential oil yields were comparable to those obtained in laboratory experiments. All of this demonstrates that PTC is suitable for use in agro-based industrial applications.

Dynamic performance of optimized microwave assisted extraction to obtain Eucalyptus essential oil: energy requirements and environmental impact

The dynamic performance of a microwave-assisted extraction (MAE) was studied during the extraction of eucalyptus essential oil. The effect of different process variables such as solid/liquid ratio (1:1, 1:3, or 1:5), stirring speed (0, 200, or 400 rpm), and power microwave output (360, 450, or 540 W) on obtained yield, energy requirements and environmental impact were assessed. The maximum yield was 1.26 ± 0.01% and the steam generation velocities between 4.8 and 8.8 g/min favor the extraction. In terms of environmental impact, the lowest EI99 value obtained was 6.93 ± 0.1 mPT/g. A multi-response optimization was performed to identify the operating conditions that maximize yield, while minimize energy requirements and environmental impact. Temperature dynamics and extraction kinetics were fitted to a second-order transfer function model, aimed to evaluate the role of heating patterns on the process performance. Finally, a controlled temperature experiment was carried out under the optimal conditions.

Effect of process variables on heating profiles and extraction mechanisms during hydrodistillation of eucalyptus essential oil

The effect of different process variables, such as solid/liquid ratio (1: 1, 1: 3, or 1: 5 g/ml) and stirring speeds (0, 200, or 400 rpm), was studied on the extraction mechanisms of eucalyptus essential oil obtained by hydrodistillation (HD). Different performance parameters such as obtained yield, energy requirements, and environmental impact were compared to those obtained by steam distillation (SD). Two different mathematical models were used to describe the process behavior. The obtained results indicate that the system with a solid/liquid ratio of 1:5 g/ml using a stirring speed of 400 rpm yielded maximum for HD (1.19% ± 0.01%). The environmental impact expressed as Ecopoints (EI99) ranged between 50.87 ± 13.18 and 78.17 ± 13.82 mPT/g essential oil (EO) for systems with steam injection, whereas for HD took values between 16.9 ± 0.3 and 19.24 ± 1.4 mPT/g EO at optimal operating conditions. The model parameters allowed us to identify that large amounts of steam at lower heating velocities induce a high accumulation of EO in the aqueous layer (vapor-liquid equilibrium at the interface), favoring the extraction process.

Mexican Oregano (Lippia graveolens Kunth) as Source of Bioactive Compounds: A Review

Lippia graveolens is a traditional crop and a rich source of bioactive compounds with various properties (e.g., antioxidant, anti-inflammatory, antifungal, UV defense, anti-glycemic, and cytotoxicity) that is primarily cultivated for essential oil recovery. The isolated bioactive compounds could be useful as additives in the functional food, nutraceuticals, cosmetics, and pharmaceutical industries. Carvacrol, thymol, β-caryophyllene, and p-cymene are terpene compounds contained in oregano essential oil (OEO); flavonoids such as quercetin O-hexoside, pinocembrin, and galangin are flavonoids found in oregano extracts. Furthermore, thermoresistant compounds that remain in the plant matrix following a thermal process can be priced in terms of the circular economy. By using better and more selective extraction conditions, the bioactive compounds present in Mexican oregano can be studied as potential inhibitors of COVID-19. Also, research on extraction technologies should continue to ensure a higher quality of bioactive compounds while preventing an undesired chemical shift (e.g., hydrolysis). The oregano fractions can be used in the food, health, and agricultural industries.

Crop Yield and Essential Oil Composition of Two Thymus vulgaris Chemotypes along Three Years of Organic Cultivation in a Hilly Area of Central Italy

Thymus vulgaris L. is one of the most commonly used medicinal and aromatic plants (MAPs), owing to a range of therapeutic properties of its essential oil. Plant growth, biomass yield, essential oil content and composition are influenced by chemotype, environmental conditions, cultivation techniques and vegetative development. Since in MAPs cultivation special attention is paid on high quality of raw material, the adoption of sustainable agriculture methods is of pivotal importance. Therefore, we evaluated the agronomic and qualitative performances of two Thymus vulgaris L. chemotypes, organically cultivated under the Mediterranean climate of hilly lands of central Italy for three consecutive years (2017–2019). Along the trial, total above-ground dry biomass significantly increased from the 1st to 3rd year after planting and large variations in the main biological, biometric and productive traits were observed between the two chemotypes. The ‘thymol’ chemotype EO obviously showed thymol as the major constituent (51.26–49.87%) followed by γ-terpinene and p-cymene. The ‘linalool’ chemotype EO showed high percentages of oxygenated monoterpenes (about 90%) with linalool (75%), linalyl acetate (8.15%) and b-caryophyllene (3.2%) as main constituents. This study highlighted that T. vulgaris can be successfully organically grown in the hilly lands of Tuscany, with interesting biomass and essential oil yields, even though the plants were in the initial years of crop establishment (start in 2017). The introduction of this species into organic cultivation systems could contribute to obtain high-quality raw material, as well as to enhance crop rotation diversification, which is of pivotal importance in the management of organic farms.

Essential oils: A promising eco-friendly food preservative

Essential oils (EOs) are natural, volatile and aromatic liquids extracted from special plants. EOs are complex mixture of secondary metabolites (terpenes, phenolic compounds, alcohol). EOs possess a wide range of biological activities including antioxidant, antimicrobial and anti-inflammatory ones. Particularly, EOs exhibit pronounced antibacterial and food preservative properties that represent a real potential for the food industry. Numerous EOs have the potential to be used as a food preservative for meat and meat products, vegetables and fruits as well as for dairy products. The main obstacles for using EOs as food preservatives are their safety limits, marked organoleptic effects and possible contamination by chemical products such as pesticides. This review aims to provide an overview of current knowledge about EOs food preservative properties with special emphasis on their antibacterial activities and to support their uses as natural, eco-friendly, safe and easily biodegradable agents for food preservation.

GEKKO Optimization Suite

This paper introduces GEKKO as an optimization suite for Python. GEKKO specializes in dynamic optimization problems for mixed-integer, nonlinear, and differential algebraic equations (DAE) problems. By blending the approaches of typical algebraic modeling languages (AML) and optimal control packages, GEKKO greatly facilitates the development and application of tools such as nonlinear model predicative control (NMPC), real-time optimization (RTO), moving horizon estimation (MHE), and dynamic simulation. GEKKO is an object-oriented Python library that offers model construction, analysis tools, and visualization of simulation and optimization. In a single package, GEKKO provides model reduction, an object-oriented library for data reconciliation/model predictive control, and integrated problem construction/solution/visualization. This paper introduces the GEKKO Optimization Suite, presents GEKKO’s approach and unique place among AMLs and optimal control packages, and cites several examples of problems that are enabled by the GEKKO library.