Effect of Thymol and Nanostructured Lipid Carriers (NLCs) Incorporated with Thymol as Antimicrobial Agents in Sausage

Effect of astaxanthin and carvacrol co-encapsulated emulsion and chitosan on the physicochemical, rheological, and antimicrobial properties in nitrite-free meat spread

The quality and safety of meat products are critical concerns in the food industry, and consumer demand for clean-label products is increasing. To meet these needs, this study aimed to develop a nitrite-free meat spread using an astaxanthin (0.04 wt%) and carvacrol (15 wt%) co-encapsulated emulsion (AE) and chitosan. Thermal stability and antimicrobial activity of prepared AE were evaluated. Nitrite-free meat spreads were formulated by adding astaxanthin and carvacrol-containing oil (AO), AE, and/or chitosan, and physicochemical, rheological, and antimicrobial properties were assessed. Adding AE, and/or 1 % chitosan improved the physicochemical and antimicrobial properties of the meat spreads. AE increased the unsaturated fatty acid content, improved redness, reduced cooking loss, and enhanced emulsion stability. Microsurface and rheological analyses revealed a more uniform fat/oil distribution and lower textural values in samples containing AE. AE and/or chitosan also enhanced microbiological stability. Correlation analysis suggested that AE and/or chitosan could effectively replace nitrite.

Liposome/chitosan coating film bioplastic packaging for Litchi fruit preservation

Chitosan is an ideal coating film for food preservation, but the performance of a single chitosan coating film is not good. Herein, the liposome was prepared by embedding copper nanoparticles (CuNPs) and thyme essential oil (TEO) in the hydrophilic and hydrophobic double-domain structure formed by phospholipids, and combining with chitosan to obtain a chitosan-based coating film for litchi preservation. The liposome was well-dispersed and stable with an average particle size of about 190 nm. The liposome showed excellent controllable release properties, and the cumulative release rate of TEO was 65.17 % and that of CuNPs was 15.17 % after 7 days. Furthermore, the oxygen and water vapor barrier properties of the coating film were greatly improved. Importantly, the film possessed effective antioxidant, antibacterial activity and excellent safety, which presents a better fresh-keeping effect on litchi. This study provides insights into the design and manufacture of food packaging for controllable and long-lasting preservation.

Characterization of sodium alginate film containing zein-Arabic gum nanoparticles encapsulated with oregano essential oil for chilled pork packaging

Chilled pork retains most of its nutrients but is prone to deterioration during the production-to-consumption process. To address this issue this study aimed to develop zein-Arabic gum composite nanoparticles loaded with oregano essential oil (ZAG-OEO) and incorporate them into sodium alginate films to enhance the freshness and shelf life of chilled pork. Sodium alginate, known for its excellent film-forming properties, was selected as the matrix to prepare ZAG-OEO-containing sodium alginate films (SA-ZAG-OEO). The results revealed that the tensile strength and elongation at break of the prepared films were 47.73 ± 2.15 MPa and 6.27 ± 0.21 %, respectively, at a 2.5 % nanoparticle concentration. The water contact angle of the films incorporating nanoparticles reached 81.5 ± 1.95°. The incorporation of nanoparticles enhanced the thermal stability and antibacterial activity of the films. The prepared films were utilized for the storage of chilled pork, and the quality changes were analyzed. The results demonstrate that SA-ZAG-OEO films inhibit microbial growth and lipid oxidation, thereby delaying pork spoilage. This study offers new insights into extending the shelf life of chilled pork and developing advanced meat preservation methods for the future development of the meat industry.

Effect of cinnamaldehyde-nanoemulsion and nanostructured lipid carriers on physicochemical attributes of reduced-nitrite sausages

This study aimed to produce cinnamaldehyde (CA)-loaded nanostructured lipid carriers (NLC) and nanoemulsion (NE) to replace nitrite in sausage. The NLC and NE droplet sizes were 132 and 116 nm with encapsulation efficiency of 98 and 96 %, respectively. In in vitro antimicrobial assessment, the free CA and NE showed higher microbial activity against S. aureus and E. coli than NLC. Meanwhile, NE showed a faster release profile for CA than NLC. Among the samples, NE and NE + nitrite indicated the lowest peroxide value (3.7 ± 0.1), TVBN amount (8.6 ± 0.2), acidity (0.3 ± 0.02), microbial quality (against E. coli, C. perfringens, lactic acid bacteria, psychrophilic bacteria, total mold and yeast, and total viable counts), and sensory attribute, while the NE + nitrite sample exhibited better color properties and higher oxymyoglobin content (5-10 % higher). Therefore, NE + nitrite can be the best choice due to supporting the different quality parameters of sausage.

A comparative study between the performance of thymol-nanoemulsion and thymol-loaded nanostructured lipid carriers on the textural, microbial, and sensory characteristics of sausage

The objective of this research was to compare the function of thymol-loaded nanostructured lipid carriers (NLC) and a thymol-nanoemulsion (NE) with nitrite (120 mg/kg) on quality parameters of sausage. The droplet size of the NLC and NE was 140 and 86.39 nm with encapsulation efficiency of 97 and 94%, respectively. The results on sausage showed that all samples containing NLC and NE exhibited the lowest increase in peroxide value, total volatile base-nitrogen, and TBA with the highest inhibitory effect on the growth of E. coli, C. perfringens, lactic acid bacteria, psychrophilic bacteria, mold and yeast, and total viable counts as well as good texture and sensory attributes with the best results in the NLC + nitrite and NE + nitrite samples. The L* and a* values were relatively higher in the samples treated with nitrite, NLC + nitrite, and NE + nitrite after 4-week storage. This increase in redness was associated with the maintenance of oxymyoglobin levels and a decrease in metmyoglobin production. The results of this study indicated that the combined use of NLC/NE (particularly NE) with 60 mg/kg nitrite significantly improved the oxidative and color stability, and delayed the spoilage and off-flavor in sausage.

Gel-Dispersed Nanostructured Lipid Carriers Loading Thymol Designed for Dermal Pathologies

Purpose

Acne vulgaris is one of the most prevalent dermal disorders affecting skin health and appearance. To date, there is no effective cure for this pathology, and the majority of marketed formulations eliminate both healthy and pathological microbiota. Therefore, hereby we propose the encapsulation of an antimicrobial natural compound (thymol) loaded into lipid nanostructured systems to be topically used against acne.

Methods

To address this issue, nanostructured lipid carriers (NLC) capable of encapsulating thymol, a natural compound used for the treatment of acne vulgaris, were developed either using ultrasonication probe or high-pressure homogenization and optimized using 22-star factorial design by analyzing the effect of NLC composition on their physicochemical parameters. These NLC were optimized using a design of experiments approach and were characterized using different physicochemical techniques. Moreover, short-term stability and cell viability using HaCat cells were assessed. Antimicrobial efficacy of the developed NLC was assessed in vitro and ex vivo.

Results

NLC encapsulating thymol were developed and optimized and demonstrated a prolonged thymol release. The formulation was dispersed in gels and a screening of several gels was carried out by studying their rheological properties and their skin retention abilities. From them, carbomer demonstrated the capacity to be highly retained in skin tissues, specifically in the epidermis and dermis layers. Moreover, antimicrobial assays against healthy and pathological skin pathogens demonstrated the therapeutic efficacy of thymol-loaded NLC gelling systems since NLC are more efficient in slowly reducing C. acnes viability, but they possess lower antimicrobial activity against S. epidermidis, compared to free thymol.

Conclusion

Thymol was successfully loaded into NLC and dispersed in gelling systems, demonstrating that it is a suitable candidate for topical administration against acne vulgaris by eradicating pathogenic bacteria while preserving the healthy skin microbiome.

Effect of nanocomposite alginate-based edible coatings containing thymol-nanoemulsion and/or thymol-loaded nanostructured lipid carriers on the microbial and physicochemical properties of carrot

In this study, the effect of thymol-nanoemulsion (NE) and thymol-loaded nanostructured lipid carriers (NLC) on the physiological and microbial quality of carrot was investigated. The NE and NLC droplet sizes were 86 and 140 nm with encapsulation efficiency of 97 and 94 %, respectively. The minimum inhibitory concentration and minimum bactericidal concentration of thymol decreased in NE and increased in NLC against E. coli and S. aureus. Moreover, thymol-containing coatings exhibited a higher peroxidase activity, total phenolic content, flavonoid content, DPPH radical scavenging activity, pH, and lower respiration rate, TSS, weight loss, and decay with the preference for samples coated with NLC and NE (particularly NLC). The NE and NLC treatments significantly reduced the total viable, mold and yeast, lactic acid bacteria, and Enterobacteriaceae counts compared to the free thymol-containing coating. Results showed that the application of NE and NLC containing alginate-based coating (with the preference for NLC) improved the postharvest quality of carrot and extended its shelf life. Meanwhile, the separate application of these systems gave better results than the simultaneous application of both systems in one sample.

Improving the performance of Ca-alginate films through incorporating zein-caseinate nanoparticles-loaded cinnamaldehyde

This study aimed to fabricate and characterize the Ca-alginate films functionalized by incorporating zein nanoparticles containing cinnamaldehyde (CA). The zein nanoparticles were coated with Na-caseinate (CN) to inhibit the precipitation of zein in the alginate solution. Afterward, the physical, mechanical, morphological, and barrier properties of the nanocomposite films were evaluated. The particle sizes of different zein nanoparticles (with/without CA and CN) ranged between 43.58 and 251.66 nm. The addition of free CA, zein, and CN nanoparticles significantly increased the thickness, opacity, thermal stability, and water contact angle and improved the mechanical properties of the films. The water vapor permeability was not affected but the antimicrobial activity was improved on fresh-cut apples. The lightness of nanocomposite films decreased and the yellowness and greenness increased. According to SEM and AFM images, a dense and organized interlayer arrangement with a rougher surface was detected in the nanocomposite films. FTIR analysis showed that no new interactions were formed between the Ca-alginate and zein/CN nanoparticles. An excellent sustained CA release into the water was observed for the CA/zein nanoparticles-loaded alginate films. Overall, the results showed that Ca-alginate nanocomposite films of zein nanoparticles have good potential to carry hydrophobic bioactive compounds for specific pharmaceutical and food applications.

Thymol encapsulated chitosan-Aloe vera films for antimicrobial infection

Wound healing is an extremely intricate process involving various potential factors that can contribute towards delayed healing, one of them being bacterial colonization. The current research addresses this issue through the development of herbal antimicrobial films that can be stripped off easily, formed using an essential oil component thymol, biopolymer chitosan, and herbal plant Aloe vera. In comparison to the conventionally used nanoemulsions, thymol encapsulated in chitosan-Aloe vera (CA) film exhibited high encapsulation efficiency (95.3 %) with alleviated physical stability, as established using a high zeta potential value. The pronounced loss of crystallinity, validated using X-ray diffractometry, combined with the results obtained from Infrared and Fluorescence spectroscopic analysis, confirmed the encapsulation of thymol in CA matrix through hydrophobic interactions. This encapsulation increases the spaces between biopolymer chains facilitating greater intrusion of water, conducive for preventing the possibility of bacterial infection. Antimicrobial activity was tested against various pathogenic microbes such as Bacillus, Staphylococcus, Escherichia, Pseudomonas, Klebsiella and Candida. Results showed potential antimicrobial activity in the prepared films. Release test was also run at 25 °C suggesting a two-step biphasic release mechanism. The encapsulated thymol had higher biological activity, as assessed by antioxidant DPPH assay, likely due to improved dispersibility.

Nano-Encapsulated Essential Oils as a Preservation Strategy for Meat and Meat Products Storage

Consumers today demand the use of natural additives and preservatives in all fresh and processed foods, including meat and meat products. Meat, however, is highly susceptible to oxidation and microbial growth that cause rapid spoilage. Essential oils are natural preservatives used in meat and meat products. While they provide antioxidant and antimicrobial properties, they also present certain disadvantages, as their intense flavor can affect the sensory properties of meat, they are subject to degradation under certain environmental conditions, and have low solubility in water. Different methods of incorporation have been tested to address these issues. Solutions suggested to date include nanotechnological processes in which essential oils are encapsulated into a lipid or biopolymer matrix that reduces the required dose and allows the formation of modified release systems. This review focuses on recent studies on applications of nano-encapsulated essential oils as sources of natural preservation systems that prevent meat spoilage. The studies are critically analyzed considering their effectiveness in the nanostructuring of essential oils and improvements in the quality of meat and meat products by focusing on the control of oxidation reactions and microbial growth to increase food safety and ensure innocuity.