Background There is an increased consumer demand for products derived from natural sources or containing natural compounds used to preserve or improve food quality and/or human health. Carvacrol and thymol, two phenolic, monoterpene isomers, extracted from natural sources such as oregano and thyme, showed antioxidant, antimicrobial, antihypertensive, immunomodulatory and anticancer properties. They have also had applications in functional food formulations, influenced food quality and positively affected human health. Scope and approach This review aims to cover the most recent findings related to bioactivities of carvacrol and thymol along with their mode of impact on human health and food systems. It also covers the recent applications of carvacrol and thymol with food products, and as nutraceuticals. Their possible use against SARS-CoV-2 virus and on human health are also reviewed. Key findings and conclusions Recently, carvacrol and thymol have been successfully used in products, showing the potential to extend the shelf-life of various foods. Moreover, both compounds showed a positive impact on human health and are considered safe for consumption. Carvacrol has also been reported to have antiviral properties, while in silico analyses suggested they can be used as supportive drugs for combating the SARS-CoV-2 virus.

Biological activity of plant-based carvacrol and thymol and their impact on human health and food quality

In food packaging, smart indicator films based on natural resources have greatly attracted researchers to minimize the environmental issues as well as to satisfy consumer preferences for food safety. In this research, pH-sensitive films were prepared using purple-fleshed sweet potato starch (SPS) and sweet potato peel (SPP). Two categories of the film (i) SPS and (ii) SPS/SPP, were fabricated via solvent casting technique, incorporating different concentrations of commercial purple sweet potato anthocyanin (CA) at 0%, 1%, 1.5%, and 2% (w/v) and the physicochemical, mechanical, thermal, and morphological properties of the films were investigated. The thickness, water solubility, and swelling degree of the films increased with the increment of CA, whereas there were no significant changes in the water content (WC) of the films. Water vapor permeability (WVP) was decreased for SPS films while statistically similar for SPS/SPP films. The addition of CA reduced the tensile strength (TS) and tensile modulus (TM) yet increased the elongation at break (EaB) of the films as compared to films without CA. The FTIR results confirmed the immobilization of anthocyanin into the film. In SEM images, roughness in the surfaces of the CA-associated films was observed. A reduction of thermal stability was found for the films with anthocyanin except for the SPS/SPP CA 2% film. Furthermore, the CA-associated films showed a remarkable color response when subjected to pH buffers (pH 1 to 12) and successfully monitored chicken freshness. The fastest color migration was observed in acidic conditions when the films were immersed into aqueous, acidic, low fat, and fatty food simulants. The findings of this work demonstrated that the developed pH indicator films have the potential to be implemented as smart packaging to monitor food freshness and quality for safe consumption.

Characterization of Anthocyanin Associated Purple Sweet Potato Starch and Peel-Based pH Indicator Films.

Currently, edible films have been increasingly explored to solve muscle food spoilage during storage, especially through the incorporation of plant extracts to develop edible packaging materials. Natural polymers matrices with plant extracts are befitting for fabricating edible films by casting methods. In the films system, the structure and physicochemical properties were strengthened via chemical interactions between active molecules in plant extracts and the reactive groups in the polymer chain. The antibacterial and antioxidant properties were dramatically reinforced through both physical and chemical actions of the plant extracts. Additionally, edible films imbedded with color-rich plant extracts could be considered as potential sensitive indicators to monitor the spoilage degree of muscle foods in response to change in gas or temperature. Furthermore, these films could increase sensory acceptability, improve quality and prolong the shelf life of muscle foods. In this article, the types, preparation methods and reinforcing properties of the edible films with plant extracts were discussed. Also, the applications of these films were summarized on quality maintenance and shelf-life extension and intelligent monitoring in muscle foods. Finally, a novel technology for film preparation achieving high-stability and sustained release of active compounds will become an underlying trend for application in muscle food packaging.

Active edible films with plant extracts: a updated review of their types, preparations, reinforcing properties, and applications in muscle foods packaging and preservation.

Biosurfactants are in demand by the global market as natural commodities that can be added to commercial products or use in environmental applications. These biomolecules reduce the surface/interfacial tension between fluid phases and exhibit superior stability to chemical surfactants under different physico-chemical conditions. Biotechnological production of biosurfactants is still emerging. Fungi are promising producers of these molecules with unique chemical structures, such as sophorolipids, mannosylerythritol lipids, cellobiose lipids, xylolipids, polyol lipids and hydrophobins. In this review, we aimed to contextualize concepts related to fungal biosurfactant production and its application in industry and the environment. Concepts related to the thermodynamic and physico-chemical properties of biosurfactants are presented, which allows detailed analysis of their structural and application. Promising niches for isolating biosurfactant-producing fungi are presented, as well as screening methodologies are discussed. Finally, strategies related to process parameters and variables, simultaneous production, process optimization through statistical and genetic tools, downstream processing and some aspects of commercial products formulations are presented.

/pdf/fungal-biosurfactants-from-nature-to-biotechnological-3aa2tqlo6n.pdf

Fungal biosurfactants, from nature to biotechnological product: bioprospection, production and potential applications

Major factors affecting the characteristics of starch based biopolymer films

Cold plasma in food processing: Design, mechanisms, and application

For the first time, it was investigated the film effects of surface-active agents - mannosylerythritol lipids-B (MEL) and sodium-dodecyl-sulfate (SDS) - into biodegradable films. The films were produced by casting technique using cassava starch, glycerol as the plasticizer; surface-active agents (20 g/100 g of starch), and water. The mechanical, functional, crystalline and antibacterial properties of films were characterized. Starch-films containing MEL were more flexible, water vapour permeable, and hydrophilic rather than control or starch-films containing SDS. On the other hand, the SDS led to films with higher rigidity, resistant at the break, crystalline, water-soluble, less flexible and water vapour permeable than the control or starch-films containing MEL. MEL can be used as a surface-active agent in biodegradable films, since MEL enhanced the wettability, resulting in superhydrophilic films. Regarding antimicrobial properties, SDS and MEL are both (bio)surfactants which implies that they have similar antimicrobial mechanisms. However, starch-films containing MEL or SDS showed different antibacterial properties. Starch-films containing SDS presented well-defined inhibition halos against the Weissella viridescens and Staphylococcus aureus, whereas starch-films containing MEL did not present well-defined inhibition halos, since MEL do not have diffusion property into agar. Therefore, MEL and SDS interact differently with the starch matrix, and thus, producing cassava films with unique properties.

Denise Adamoli Laroque

Papers

Cold plasma in food processing: Design, mechanisms, and application

Production of active cassava starch films; effect of adding a biosurfactant or synthetic surfactant

Active cellulose acetate‐carvacrol films: Antibacterial, physical and thermal properties