Optimization of preparation conditions of eucalyptus essential oil microcapsules by response surface methodology

Efficient encapsulation of Hinoki essential oil with β-cyclodextrin using an ultrasound-aided co-precipitation technique for dual anti-Listeria monocytogenes and anti-Staphylococcus aureus activities

Listeria monocytogenes (L. monocytogenes) and Staphylococcus aureus (S. aureus) are widely acknowledged as two of the most dangerous foodborne pathogens. Nevertheless, reports on the development of non-toxic food preservatives that specifically target these two bacterial strains are scarce. Here, we present an inclusion complex (IC) of Hinoki essential oil with β-cyclodextrin, which exhibited dual anti-L. monocytogenes and anti-S. aureus activities. For the first time, an innovative ultrasound-aided co-precipitation technique was utilized for the preparation of IC. Compared with the traditional co-precipitation method, this new technique demonstrated superior encapsulation and time efficiencies, making it well-suited for large-scale production. X-ray diffraction and scanning electron microscopy analyses revealed a transition in the morphological and crystal structures after formation of the IC. Fourier transform infrared spectroscopy and Raman spectroscopy analyses indicated that Hinoki essential oil was effectively encapsulated by β-cyclodextrin. The differential scanning calorimetry and thermogravimetric thermograms indicated that the formed IC was more thermally stable than the free Hinoki essential oil. Importantly, 100 % antibacterial ratios for both L. monocytogenes and S. aureus were determined, indicating that the IC prepared in this study is a promising food preservative.

Anti-Candida and Anti-Leishmanial Activities of Encapsulated Cinnamomum verum Essential Oil in Chitosan Nanoparticles

Nanoencapsulation is widely considered as a highly effective strategy to enhance essential oils' (EO) stability by protecting them from oxidative deterioration and evaporation. The present study aims to optimize and characterize an efficient technique for encapsulating Cinnamomum (C.) verum essential oil into chitosan nanoparticles using response surface methodology (RSM). Moreover, the optimized C. verum EO nanoparticle was investigated for its antibacterial (against Gram-positive and Gram-negative bacteria), antifungal (against Candida albicans), and antiparasitic activity (against Leishmania parasites). Five parameters were investigated using a Plackett-Burman and Box-Behnken statistical design: the chitosan molecular weight, TPP concentration, C. verum EO/chitosan ratio, mixing method, and the duration of the reaction. Encapsulation efficiency and anti-candida activity were considered as responses. The antibacterial, anticandidal, and anti-leishmanial activities were also assessed using a standard micro-broth dilution assay and the cytotoxicity assay was assessed against the macrophage cell line RAW 264.7. The optimized nanoparticles were characterized using Fourier transform infrared spectroscopy, Zeta potential, and scanning electron microscopy. The study results indicated that under optimal conditions, the nanoencapsulation of C. verum EO into chitosan nanoparticles resulted in an encapsulation efficiency of 92.58%, with a regular distribution, a nanoparticle size of 480 ± 14.55 nm, and a favorable Zeta potential of 35.64 ± 1.37 mV. The optimized C. verum EO/chitosan nanoparticles showed strong antifungal activity against C. albicans pathogens (CMI = 125 µg mL-1), notable antibacterial activity against both Gram-positive and Gram-negative bacteria (ranging from 125 to 250 µg mL-1), high leishmanicidal potential against the promastigotes form of L. tropica and L. major (IC50 = 10.47 and 15.09 µg mL-1, respectively), and a four-fold cytotoxicity reduction compared to non-encapsulated essential oil. These results suggest that C. verum EO-loaded chitosan nanoparticles could be a promising delivery system for the treatment of cutaneous Candida albicans infections.

The role of essential oils in maintaining the postharvest quality and preservation of peach and other fruits

Fruits are highly susceptible to postharvest losses induced majorly by postharvest diseases. Peach are favored by consumers because of their high nutritional value and delicious taste. However, it was easy to be affected by fungal infection. The current effective method to control postharvest diseases of fruits is to use chemical fungicides, but these chemicals may cause adverse effects on human health and the residual was potentially harmful to nature and the environment. So, it is especially important to develop safe, non-toxic, and highly effective strategies for the preservation of the fruits. Essential oil, as a class of the natural bacterial inhibitor, has been proven to exhibit strong antibacterial activity, low toxicity, environmental friendliness, and induce fruit resistance to microorganism, which could be recognized as one of the alternatives to chemical fungicides. This paper reviews the research progress of essential oils (Eos) in the storage and preservation of fruits, especially the application in peach, as well as the application in active packaging such as edible coatings, microcapsules, and electrospinning loading. Electrospinning can prepare a variety of nanofibers from different viscoelastic polymer solutions, and has broad application prospects. The paper especially summarizes the application of the new Eos technology on peach. The essential oil with thymol, eugenol, and carvacrol as the main components has a better inhibitory effect on the postharvest disease of peaches, and can be further applied. PRACTICAL APPLICATIONS: As an environmentally friendly natural antibacterial agent, essential oil can be used as a substitute for chemical preservatives to keep fruits fresh. This paper summarizes the different preservation methods of essential oils for fruits, and especially summarizes the different preservation methods of essential oils for peaches after harvesting, as well as their inhibitory effects on pathogenic fungi. It could provide ideas for preservation of fruits and vegetables by essential oils.

Encapsulation of Zanthoxylum bungeanum essential oil to enhance flavor stability and inhibit lipid oxidation of Chinese-style sausage

BACKGROUND

Zanthoxylum bungeanum essential oil (ZBEO) is a popular seasoning, commonly used in the food industry. It contains many easily degraded and highly volatile bioactive substances. Control of the stability of the bioactive substances in ZBEO is therefore very important in the food industry.

RESULTS

In this study, microencapsulation was applied to improve ZBEO stability. The key parameters for microcapsule preparation were optimized by the Box-Behnken design method, and the optimum conditions were as follows: ratio of core to wall, 1:8; ratio of hydroxypropyl-α-cyclodextrin (HPCD) to soy protein isolate (SPI), 4; total solids content, 12%; and homogenization speed, 12 000 rpm. Antioxidant experiments have indicated that tea polyphenols (TPPs) effectively inhibited hydroxy-α-sanshool degradation in ZBEO microcapsules. Application of ZBEO microcapsules in Chinese-style sausage effectively inhibited lipid oxidation in sausages and protected hydroxy-α-sanshool and typical volatiles from volatilization and degradation during sausage storage.

CONCLUSION

The results suggested that ZBEO microencapsulation is an effective strategy for improving the stability of its bioactive components and flavor ingredients during food processing. © 2022 Society of Chemical Industry.

Antibacterial Activity and Mechanism of Polygonum orientale L. Essential Oil against Pectobacterium carotovorum subsp. carotovorum

Infected by Pectobacterium carotovorum subsp. carotovorum (Pcc), the quality of Chinese cabbage could severely decline. Using chemical bactericides to control Pcc could cause food safety problems. Thus, we investigated the optimum extraction conditions, antibacterial activity, chemical compounds and antibacterial mechanism of Polygonum orientale L. essential oil (POEO) against Pcc in order to search a new way to control Pcc. The optimum extraction conditions of POEO (soaking time 2.6 h, extraction time 7.7 h and ratio of liquid to solid 10.3 mL/g) were optimized by response surface methodology. The minimum inhibitory concentration (MIC) of POEO against Pcc was 0.625 mg/mL. The control efficiency of protective activity of POEO against Pcc was 74.67~92.67%, and its curative activity was 76.00~93.00%. Then, 29 compounds were obtained by GC-MS; the prime compounds of POEO were phytol, phytone, n-pentacosane, 1-octen-3-ol and β-ionone. It was verified that, compared with control samples, POEO destroyed cell morphology. It increased surface potential, increased hydrophobicity, damaged cell walls, destroyed the integrity and permeability of cell membrane, reduced membrane potential (MP), and changed membrane protein conformation. It inhibited the activities of pyruvate kinase (PK), succinate dehydrogenase (SDH) and adenosine triphosphatase (ATPase). Briefly, the results of this study demonstrate that POEO showed effective inhibitory activity against Pcc, thus POEO could have potential application in controlling Pcc.

Susceptibility of Tribolium castaneum (Coleoptera: Tenebrionidae) to the Fumigation of Two Essential Satureja Oils: Optimization and Modeling

Due to the numerous side effects of synthetic pesticides, including environmental pollution, threats to human health, harmful effects on non-target organisms and pest resistance, the use of alternative healthy, available and efficient agents in pest management strategies is necessary. In this paper, the susceptibility of the cosmopolitan, polyphagous, stored-product pest Tribolium castaneum (red flour beetle) to the fumigation of the essential oils of two important medicinal and food additive plants, Satureja hortensis and S. intermedia, was investigated. The insecticidal properties of the essential oils were modeled and optimized using response surface methodology. It was found that a maximum significant mortality of 94.72% and 92.97% could be achieved within 72 h with the applications of 55.15 µL/L of S. hortensis (with the linear model) and 58.82 µL/L of S. intermedia (with the quadratic model), respectively. There were insecticidal terpenes and phenylpropanoids in both essential oils, including thymol (50.8%), carvacrol (11.2%) and p-cymene (13.4%), in the S. intermedia and estragole (68.0%) and methyl eugenol (5.6%) in the S. hortensis. It was suggested that the essential oils of S. hortensis and S. intermedia could be offered as promising pesticidal agents against T. castaneum for further studies in the management of such pests instead of detrimental synthetic pesticides.