Supercritical CO2 iof LDPE films with terpene ketones as biopesticides against corn weevil (Sitophilus zeamais)

Elucidating solvent effects on lipase-catalyzed peroxyacid synthesis through activity-based kinetics and molecular dynamics

Peroxyacid synthesis is the first step in Prilezhaev epoxidation, which is an industrial method to form epoxides. Motivated by the development of a kinetic model as a tool for solvent selection, the effect of solvent type and acid chain length on the lipase-catalyzed peroxyacid synthesis was studied. A thermodynamic activity-based ping-pong kinetic expression was successfully applied to predict the effect of the reagent loadings in hexane. The activity-based reaction quotients provided a prediction of solvent-independent equilibrium constants. However, this strategy did not achieve satisfactory estimations of initial rates in solvents of higher polarity. The lack of compliance with some assumptions of this methodology could be confirmed through molecular dynamics calculations i.e. independent solvation energies and lack of solvent interaction with the active site. A novel approach is proposed combining the activity-based kinetic expression and the free binding energy of the solvent with the active site to predict kinetics upon solvent change. Di-isopropyl ether generated a strong interaction with the enzyme's active site, which was detrimental to kinetics. On the other hand, toluene or limonene gave moderate interaction with the active site rendering improved catalytic yield compared with less polar solvents, a finding sharpened when peroctanoic acid was produced.

Advances in Environmentally Friendly Techniques and Circular Economy Approaches for Insect Infestation Management in Stored Rice Grains

Rice (Oryza sativa L.) is a staple food for about half of the world's population. Therefore, it is important to search for solutions that minimise losses and production costs for producers and ensure food quality and safety for consumers. Improved methods for the detection and monitoring of hidden infestations are useful for adopting infestation control measures. Chemical methods are used to prevent rice losses due to infestations; changing this situation, however, is of the utmost importance, as it harms the environment and human health. The management of infestation by controlled storage conditions, namely temperature and atmosphere composition and the use of current fossil-based packaging with modified atmospheres, is well recognised. The use of environmentally friendly solutions is promising, but it is necessary to perform a life-cycle assessment and cost analysis to evaluate their effectiveness. According to the principles of circular economy, the integration of the best-selected treatments/solutions for insect management, along with the use of biopackaging from rice by-products are recommended. This review describes the methods of detection and control of infestation as well as several promising alternatives to chemical treatments; however, more research is needed in order to obtain effective technological solutions that can be applied at an industrial scale.

Effect of the Processing Conditions on the Supercritical Extraction and Impregnation of Rosemary Essential Oil in Linear Low-Density Polyethylene Films

The supercritical fluid extraction of essential oil from rosemary leaves and its subsequent impregnation in linear low-density polyethylene (LLDPE) films were studied. The effects of temperature (318 and 338 K), pressure (15 and 25 MPa) and rosemary particle size (0.9 and 0.15 mm) on the extraction yield were investigated. Impregnation assays were developed at two different values of pressure (12 and 20 MPa), temperature (308 and 328 K), and impregnation time (1 and 5 h). The extraction yield of rosemary essential oil was increased by increasing pressure and decreasing particle size and temperature. ANOVA results showed that temperature, pressure, and time significantly impacted the essential oil impregnation yield in LLDPE films. The maximum impregnation yield (1.87 wt. %) was obtained at 12 MPa, 328 K, and 5 h. The antioxidant activity and the physical-mechanical properties of impregnated films were analyzed. The IC50 values for all the impregnated LLDPE samples were close to the IC50 value of the extract showing that the impregnated films have a significant antioxidant activity.

Can Essential Oils Be a Natural Alternative for the Control of Spodoptera frugiperda? A Review of Toxicity Methods and Their Modes of Action

Spodoptera frugiperda is a major pest of maize crops. The application of synthetic insecticides and the use of Bt maize varieties are the principal strategies used for its control. However, due to the development of pesticide resistance and the negative impact of insecticides on the environment, natural alternatives are constantly being searched for. Accordingly, the objective of this review was to evaluate the use of essential oils (EOs) as natural alternatives for controlling S. frugiperda. This review article covers the composition of EOs, methods used for the evaluation of EO toxicity, EO effects, and their mode of action. Although the EOs of Ocimum basilicum, Piper marginatum, and Lippia alba are the most frequently used, Ageratum conyzoides, P. septuplinervium. O. gratissimum and Siparuna guianensis were shown to be the most effective. As the principal components of these EOs vary, then their mode of action on the pest could be different. The results of our analysis allowed us to evaluate and compare the potential of certain EOs for the control of this insect. In order to obtain comparable results when evaluating the toxicity of EOs on S. frugiperda, it is important that methodological issues are taken into account.

Mass Transfer and Optical Properties of Active PET/PP Food-Grade Films Impregnated with Olive Leaf Extract

A supercritical solvent impregnation (SSI) technique was employed to incorporate, by batch- and semicontinuous-modes, bioactive olive leaf extract (OLE) into a food-grade multilayer polyethylene terephthalate/polypropylene (PET/PP) film for active food packaging applications. The inclusion of OLE in the polymer surfaces significantly modified the colour properties of the film. A correlation of 87.06% between the CIELAB colour parameters and the amount of the OLE impregnated in the film was obtained which suggests that colour determination can be used as a rapid, non-destructive technique to estimate the OLE loading in the impregnated matrices. The UV barrier and water permeability properties of the films were not significantly modified by the incorporation of OLE. The migration of OLE into a 50% (v/v) ethanol food simulant demonstrated faster release of OLE from the PP surface than from the PET surface which may be due to the different interactions between OLE and each polymer.

Biopesticide Encapsulation Using Supercritical CO2: A Comprehensive Review and Potential Applications

As an alternative to synthetic pesticides, natural chemistries from living organisms, are not harmful to nontarget organisms and the environment, can be used as biopesticides, nontarget. However, to reduce the reactivity of active ingredients, avoid undesired reactions, protect from physical stress, and control or lower the release rate, encapsulation processes can be applied to biopesticides. In this review, the advantages and disadvantages of the most common encapsulation processes for biopesticides are discussed. The use of supercritical fluid technology (SFT), mainly carbon dioxide (CO₂), to encapsulate biopesticides is highlighted, as they reduce the use of organic solvents, have simpler separation processes, and achieve high-purity particles. This review also presents challenges to be surpassed and the lack of application of SFT for biopesticides in the published literature is discussed to evaluate its potential and prospects.

Supercritical impregnation for food applications: a review of the effect of the operational variables on the active compound loading

The scCO₂-assisted impregnation process has arisen as an effective method to impregnate solid materials. Its multiple advantages include high diffusion, it allows to obtain free-solvent materials and to operate under low temperatures, which permits to process thermolabile solutes. These characteristics have allowed its application at industrial scale for the impregnation of wood with fungicides and in the last years for textile dyeing. Meanwhile, other numerous applications are still being studied at laboratory scale. One potential field of application corresponds to the food-related industry, which includes the use of scCO₂-assisted impregnation process to develop active materials for food packaging and to generate food-grade materials loaded with nutraceuticals for functional food applications. In this framework, this article summarizes the advantages and the main drawbacks with the scCO₂-assisted impregnation process. The effect of the processing variables of the scCO₂-assisted impregnation process is discussed in terms of the incorporation of active compounds within polymer structures. Including the principles and description of the process and a review of the investigated systems for a better understanding.