Effective suppression of potato tuber sprouting using polysaccharide-based emulsified films for prolonged release of citral

Fabrication of cinnamon essential oil nanoemulsions with high antibacterial activities via microfluidization

The high volatility and hydrophobicity of cinnamon essential oils (CiEO) limited their practical application. To enhance their stability and antibacterial activity, nanoemulsions encapsulating CiEO were prepared using hydroxypropyl-β-cyclodextrin/lauroyl arginate (HPCD/LAE) inclusion complexes through high-pressure microfluidization (HPM). Effects of HPM parameters on the stability and antibacterial properties of nanoemulsion were investigated. Results revealed that increased processing pressure and cycle numbers were associated with reduced droplet size and greater homogeneity in CiEO distribution. Storage and thermal stability were optimized at 100 MPa and seven cycles. Moreover, the nanoemulsions showed strong synergistic antibacterial against E. coli (19.79 mm) and S. aureus (23.61 mm) compared with LAE (11.52 mm and 12.82 mm, respectively) and CiEO alone (13.26 mm and 17.68 mm, respectively). This study provided new information for constructing CiEO nanoemulsion, which is suitable for use in the food industry.

Antioxidant-Mediated Modification of Citral and Its Control Effect on Mildewy Bamboo

To reduce the oxidative degradation of citral and improve its antimildew performance, citral was modified with natural antioxidants such as tea polyphenols, ascorbic acid, and theaflavin in the present study. Additionally, the effects of these natural antioxidants on the citral degradation rate and DPPH radical-scavenging rate, as well as the effectiveness of antioxidant-modified citral in the antimildew treatment of bamboo were investigated. Ascorbic acid, theaflavin, and tea polyphenols improved the antioxidant performance of citral to some extent, and the tea polyphenols exhibited the best antioxidant performance. When the amount of tea polyphenols added to citral reached 1.0%, the oxidative degradation of citral was effectively prevented. Compared with citral, tea-polyphenol-modified citral could reduce the efficacy of the bamboo antimildew treatment against all four mildews and the effectiveness of the antimildew treatment reached 100%. Citral modification with antioxidants reduced the amount of citral required in the treatment, thereby reducing the treatment cost for bamboo mildew.

Emulsification-based interfacial synthesis of citral-loaded hollow MIL-88A for the inhibition of potato tuber sprouting

Economic value of the global potato harvest is impacted by sprouting during storage. We examined how sprouting might be reduced or eliminated using citral, a naturally occurring component in citrus fruit peel. The current study integrated both loading and sustained release of citral using emulsification-based interfacial synthesis of hollow MIL-88A. The structural properties and compositions of MIL-88A and hollow MIL-88A were confirmed using SEM, EDS, and XRD. BET analysis showed a surface area of 30.36 m² g^-1, pore volume of 0.21 cm³ g^-1, and an average pore radius of 13.56 nm for hollow MIL-88A. Citral was successfully loaded into 10 g of MIL-88A and hollow MIL-88A, with a total citral load of 0.21 cm³ and 1.82 cm³, respectively. The citral-loaded hollow MIL-88A induced a sustained release of citral, which effectively inhibited the sprouting, leading to higher starch content by 41%, lower weight losses, reducing sugar content, α-Amylase, β-amylase, and starch phosphorylase activities by 75%, 55%, 34%, 31%, and 43%, respectively. The citral-loaded hollow MIL-88A might inhibit sprouting by suppressing gibberellin and indole-3-acetic acid while maintaining abscisic acid.

Oligomers of Carboxymethyl Cellulose for Postharvest Treatment of Fresh Produce: The Effect on Fresh-Cut Strawberry in Combination with Natural Active Agents

In this study, oligomers of carboxymethyl cellulose (O-CMC) were used as a new postharvest treatment for fresh produce. The oligomers were prepared by green and cost-effective enzymatic hydrolysis and applied to prevent spoilage and improve storability of fresh-cut strawberries. The produce quality was improved by all formulations containing O-CMC in comparison to the control, as indicated by the decrease in decay incidence, weight loss (min ~2-5 times less), higher firmness, microbial load decrease, better appearance, and sensorial quality of the fruits. Natural resources: ascorbic acid, gallic acid, and vanillin were further added to enhance the beneficial effect. O-CMC with vanillin was most efficient in all of the tested parameters, exhibiting the full prevention of fruit decay during all 7 days of refrigerated storage. In addition, fruits coated with O-CMC vanillin have the smallest weight loss (%), minimum browning, and highest antimicrobial effect preventing bacterial (~3 log, 2 log) and yeast/mold contaminations. Based on the obtained positive results, O-CMC may provide a new, safe, and effective tool for the postharvest treatment of fresh produce that can be used alone or in combination with other active agents.

A Low Energy Approach for the Preparation of Nano-Emulsions with a High Citral-Content Essential Oil

Pectis elongata is found in the northern and northeastern regions of Brazil. It is considered a lemongrass due to its citric scent. The remarkable citral content and the wide antimicrobial properties and bioactive features of this terpene make this essential oil (EO) eligible for several industrial purposes, especially in cosmetics and phytotherapics. However, to address the problems regarding citral solubility, nano-emulsification is considered a promising strategy thanks to its improved dispersability. Thus, in this paper we propose a low-energy approach for the development of citral-based nano-emulsions prepared with P. elongata EO. The plant was hydrodistillated to produce the EO, which was characterized with a gas chromatograph coupled to mass spectrometry. The nano-emulsion prepared by a non-heated water titrating (low-energy) method was composed of 5% (w/w) EO, 5% (w/w) non-ionic surfactants and 90% (w/w) deionized water and was analyzed by dynamic light scattering. Levels of citral of around 90% (neral:geranial—4:5) were detected in the EO and no major alteration in the ratio of citral was observed after the nano-emulsification. The nano-emulsion was stable until the 14th day (size around 115 nm and polydispersity index around 0.2) and no major alteration in droplet size was observed within 30 days of storage. Understanding the droplet size distribution as a function of time and correlating it to concepts of compositional ripening, as opposing forces to the conventional Ostwald ripening destabilization mechanism, may open interesting approaches for further industrial application of novel, low-energy, ecofriendly approaches to high citral essential oil-based nano-emulsions based on lemongrass plants.

Proteomic analysis reveals that naturally produced citral can significantly disturb physiological and metabolic processes in the rice blast fungus Magnaporthe oryzae

Rice blast (Magnaporthe oryzae), a major fungal disease in rice producing areas all over the world as well as in China, seriously affects the safety of rice production. Citral, a mixture of Z/E and trans isomers, is a natural acycloid monoterpene compound with good bacteriostatic effect on rice blast. To further investigate the underlying molecular mechanism, a comparative proteomics analysis was conducted between citral-treated and non-treated M. oryzae spores through two-dimensional gel electrophoresis and MALDI-TOF mass spectrometry. Our analysis identified 1600-1800 proteins from M. oryzae ZB15, of which 147 were differentially expressed in 100 μg/mL citral-treated samples relative to the control group. Among these differentially expressed proteins (DEPs), 40 proteins showed significantly different expression. GO enrichment and NCBI conserved domains database analysis showed that the main groups of the cellular component were cytoplasm (23.33%), and the major molecular function categories were ion binding (31.37%), and the major categories of biological processes included small molecule metabolic process (22.22%) and transport (13.89%). Further analysis found that down-regulated proteins included the tubulin α chain, ATP synthase subunit β and malate dehydrogenase, while the tubulin β, enolase were upregulated. These DEPs could possibly limit the availability of energy required for many cellular processes and result in various physiological adaptions of M. oryzae. This study represents the first proteomic analysis of M. oryzae treated by citral and will help to uncover the mode-of-action of this biologically active compound against M. oryzae. These findings have practical implications with respect to the use of citral for fungal disease control.