Comparative study of Elyonurus muticus and Cymbopogon essential oils: potential as food preservative and surface coating of strawberries

An alginate-based edible coating containing lactic acid bacteria extends the shelf life of fresh strawberry (Fragaria × ananassa Duch.)

Edible coatings, formulated with sodium alginate and various strains of lactic acid bacteria, were evaluated for their effectiveness in extending the shelf life and mitigating microbial risks associated with strawberries. This study specifically employed strains of Lacticaseibacillus paracasei, Lacticaseibacillus rhamnosus, and Lacticaseibacillus plantarum as antimicrobial agents. Through physicochemical property analysis, the alginate-based antimicrobial coating proved most effective in reducing the strawberry weight loss rate, decay index, and ascorbic acid degradation. Over time, all treatments exhibited increased fungal growth. However, strawberries treated with alginate and lactic acid bacteria recorded lower final colony formation counts-6.82 log CFU/g for SA + LPC, 6.04 log CFU/g for SA + LGG, and 6.26 log CFU/g for SA + LP-compared to 8.73 log CFU/g in the control group. In terms of bacterial resistance under gastrointestinal conditions, L. paracasei demonstrated the highest survival rate post-simulated gastric fluid exposure, while L. plantarum showed the greatest resilience post-simulated intestinal fluid exposure. These findings underscore the efficacy of alginate-based antimicrobial coatings in not only enhancing the storage quality of strawberries but also ensuring microbial safety and potential benefits for gut health.

Antioxidant and Antimicrobial Properties and GC-MS Chemical Compositions of Makwaen Pepper (Zanthoxylum myriacanthum) Extracted Using Supercritical Carbon Dioxide

This research aimed to optimize pressure (10-20 MPa) and temperature (45-60 °C) conditions for supercritical fluid extraction (SFE) of Makwaen pepper (Zanthoxylum myriacanthum) extract (ME) in comparison to conventional hydro-distillation extraction. Various quality parameters, including yield, total phenolic compounds, antioxidants, and antimicrobial activities of the extracts, were assessed and optimized using a central composite design. The optimal SFE conditions were found to be 20 MPa at 60 °C, which resulted in the highest yield (19%) and a total phenolic compound content of 31.54 mg GAE/mL extract. IC₅₀ values for DPPH and ABTS assays were determined to be 26.06 and 19.90 μg/mL extract, respectively. Overall, the ME obtained through SFE exhibited significantly better physicochemical and antioxidant properties compared to ME obtained through hydro-distillation extraction. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that beta-pinene was the major component in the ME obtained through SFE (23.10%), followed by d-limonene, alpha-pinene, and terpinen-4-ol at concentrations of 16.08, 7.47, and 6.34%, respectively. On the other hand, the hydro-distillation-extracted ME showed stronger antimicrobial properties than the SFE-extracted ME. These findings suggest that both SFE and hydro-distillation have the potential for extracting Makwaen pepper, depending on the intended purpose of use.

Phytochemical and Biological Profile of Essential Oils of Elionurus muticus (Spreng.) Growing in Northeastern Argentina

The purpose of this study was to investigate essential oils (EOs) from leaves of Elionurus muticus growing in Northeastern Argentina regarding their physicochemical profiles as well as their biological potential. Roots of a selected E. muticus population were investigated too. For this purpose, EOs of fresh materials were obtained by steam distillation and the chemical composition was characterized by gas chromatography GC/MS-FID. Antibacterial, antioxidant and eco-toxicity activities of the essential oils (EOs) were tested by in vitro assays. The EOs showed three E. muticus chemotypes: citral (neral+geranial), acorenone+bisabolone, acorenone+geranial. EO of roots of citral population contains mainly acorenone derivatives. EOs have high antibacterial effect against Staphylococcus aureus, being found minor antibacterial effect against Gram-negative bacteria. The half-maximal inhibitory concentration of EOs against DPPH⋅ were 7.1-30.0 mg/mL and the eco-toxicity was high with LD₅₀ <39 μg/mL. Based on the findings, given the high variability in their chemical composition and biological activity of E. muticus EO and the promising yields, it could be potentially chosen for industrial applications.

Preparation and properties of chitosan-based bacteriostatic agents and their application in strawberry bacteriostatic preservation

The purpose of this study is to develop a green and safe chitosan-based preservative which can be applied in strawberry preservation. Chitosan (CS) was treated by 2,2,6,6-tetramethylpiperidine oxygen radical/laccase oxidation system (TEMPO/laccase oxidation system), which was mainly used to prepare TEMPO/laccase chitosan (TLCS). Furthermore, on this basis, the structure and performance of TLCS were also studied. The results showed that compared with CS, the solubility of TLCS improved, and the kinetic viscosity reduced significantly. Next, a cinnamaldehyde-TEMPO/laccase chitosan (CIN-TLCS) antibacterial agent was prepared by covalently combining the aldehyde group in cinnamaldehyde (CIN) and the amino group in CS. It was found that CIN combined with TLCS through covalent bonds, which changed the structure and crystallinity of TLCS. In addition, the total antioxidant capacity of CIN-TLCS also improved, which was necessary for the application of CIN-TLCS in extending shelf life. Cytotoxicity experiments showed that CIN-TLCS had no cytotoxicity. Furthermore, strawberries were used to explore the actual bacteriostatic and fresh-keeping effects of CIN-TLCS. The experiment found that CIN-TLCS could maintain the freshness of strawberries at room temperature (23 ± 1°C) for 5 days and had positive effects on strawberry color, loss-weight rate, hardness and pH. These results showed that CIN-TLCS could be used as a potential preserving agent for fruit storage. PRACTICAL APPLICATION: To obtain a green, safe and effective food preservative, chitosan (CS) was modified by a 2,2,6,6-tetramethylpiperidine oxygen radical/laccase oxidation system (TEMPO/laccase oxidation system) to get TEMPO/laccase chitosan (TLCS) and cinnamic aldehyde-TEMPO/laccase chitosan (CIN-TLCS). At the same time, the structure and antibacterial properties of TLCS and CIN-TLCS were analyzed, and their possibility as a new green and safe strawberry preservative was studied. Compared with oxazolidine, imidazole and triazole commercial drugs, CIN-TLCS has the advantages of low price, no pollution, no cytotoxicity and no drug resistance.