Nanostructured active chitosan-based films for food packaging applications: Effect of graphene stacks on mechanical properties

Bioactive food-preserving materials are based on the use of a natural antimicrobial compound loaded in a carrier material, which is able to trigger its release when requested and to modulate the rate of release, thus using either toxic or inhibitory properties against pathogens or bacteria due to food decomposition. In this study, the Schiff base formation for chitosan functionalization was achieved by the reaction of chitosan with cinnamaldehyde at different concentrations. Cinnamaldehyde is an aromatic α,β-unsaturated aldehyde, and the major component in essential oils from some cinnamon species. It has been shown to exert antimicrobial action against a large number of microorganisms including bacteria, yeasts, and mould. The formation of the Schiff base is reversible under suitable conditions, and this might allow the release of the active cinnamaldehyde from chitosan, used as the carrier. The reaction kinetics was investigated by means of rheological measurements, while infrared spectroscopy was used to assess the efficacy of the functionalization. The addition of nanometric graphene stacks to the cinnamaldehyde-functionalized chitosan films was evaluated with the aim to increase the mechanical properties of the film. Finally, the films were tested for antifungal properties with bread slices against a selected mould line.     

Preliminary study on mitigating steel reinforcement corrosion with bioactive agent

Corrosion causes over $100 billion in damage annually. Cinnamaldehyde, a bioactive agent derived from cinnamon bark, can mitigate the corrosion of metals but has a negative effect on hydration when incorporated in cementitious systems. In order to avoid these negative consequences while harnessing anti-corrosive properties, cinnamaldehyde was incorporated in a cementitious mixture through the use of lightweight aggregate (LWA). The same method was used for penetrating corrosion inhibitors in an attempt to reduce the time required for the inhibitor to reach and protect reinforcing steel. The setting time, compressive strength, heat evolution (via semi-adiabatic calorimetry), and autogenous shrinkage of the experimental mixtures were measured and an accelerated corrosion test (ACT) was used to quantify performance in a corrosive environment. Experimental mortars showed prolonged setting times, reduced compressive strength, heat evolution, and autogenous expansion. However, the experimental mortars showed an increase in time to cracking when exposed to a corrosive environment.     

肉桂醛-大豆分离蛋白可食膜的抑菌及其对冷鲜猪肉的保鲜

本文研究了添加0%,1%,2%,3%,4%,5%和6%肉桂醛含量的大豆分离蛋白膜的水溶性、水蒸气透过系数、抗拉强度和断裂伸长率的变化以及上述膜对大肠杆菌、金黄色葡萄球菌、气假单胞菌和酵母菌的抑菌活性。并研究了添加6%肉桂醛的大豆分离蛋白可食膜在冷藏温度为4℃时对冷鲜猪肉的保鲜效果。结果表明:肉桂醛含量对大豆分离蛋白膜的水溶性、水蒸气透过系数、抗拉强度和断裂伸长率均有一定影响;当大豆分离蛋白膜中肉桂醛含量为3%时能完全抑制大肠杆菌的生长,4%时能完全抑制金黄色葡萄球菌和气假单胞菌的生长,2%时即能抑制酵母菌的生长;且添加肉桂醛含量为6%的大豆分离蛋白可食膜能明显提高冷鲜猪肉的保鲜效果。     

Induction of apoptosis by cinnamaldehyde from indigenous cinnamon Cinnamomum osmophloeum Kaneh through reactive oxygen species production,glutathione depletion,and caspase activation in human leukemia K562 cells

The compositions of essential oils from leaves of two Cinnamomum osmophloeum clones (A and B) commercially cultivated by Taiwan Cinnamon Biotech Co. Ltd., in Taiwan were investigated. GC and GC–MS analyses showed that Cinnamomum osmophloeum clones A and B contain trans-cinnamaldehyde (91.15%) and cinnamyl acetate (46.39%), respectively, as the major component. This study demonstrated that cinnamaldehyde was able to induce apoptosis in a concentration-dependent manner. Cinnamaldehyde-induced cell death was characterized with changes in nuclear morphology, DNA fragmentation, and cell morphology. Furthermore, treatment with cinnamaldehyde caused a rapid loss of mitochondrial transmembrane potential, stimulation of reactive oxygen species (ROS) production, release of mitochondrial cytochrome c into cytosol, and subsequent induction of procaspase-9 and procaspase-3 processing. Taken together, these results suggest that ROS production and depletion of the glutathione that committed to cinnamaldehyde-induced apoptosis in K562 cells.     

Protein Binding Characteristics of 2′-Benzoyloxycinnamaldehyde

The protein binding characteristic of 2′-Benzoyloxycinnamaldehyde (BCA) was investigated, which has demonstrated a potent antitumor effect against several human solid tumor cell lines and in human tumor xenograft nude mice. Protein binding of BCA in human serum was 86 ± 0.91% and the predominant binding protein of BCA was fatty-acid-free human serum albumin (HSA) (81 ± 0.91%). The binding of BCA to HSA was outlined by one class, and Ka and n of BCA were 1.65 × 10⁵ M^{? 1} and 0.374, respectively. Displacement studies with fluorescence probes suggested that BCA mainly binds to site I on HSA, and BCA-induced enhancement in site II binding. The limited drug–drug interaction experiments suggested that BCA influences both site I and site II drug–HSA bindings via different mechanisms; a competitive displacement and a probable allosteric conformational change in HSA, respectively.     

In vitro enhancement of antibiotic susceptibility of drug resistant Escherichia coli by cinnamaldehyde

Cinnamaldehyde is a natural antimicrobial compound that has been found to damage the cytoplasmic membrane, inhibit septum development and cause cell elongation, as well as induce oxidative stress in Escherichia coli. Thus, cinnamaldehyde may be of value as a natural compound to enhance susceptibility of drug resistant E. coli to antibiotics in livestock production. This study examined the ability of cinnamaldehyde to increase the susceptibility of E. coli to antibiotics using the checkerboard method. Interactions between the antimicrobials were characterized using fractional inhibitory concentration (FIC) values. All tested E. coli strains were resistant to erythromycin and bacitracin but were susceptible to penicillin G and ampicillin. Strains 8WT, ATCC 23739 and 02:0627 were resistant to novobiocin and the latter two strains were also resistant to tetracycline. Cinnamaldehyde synergistically increased the susceptibility of all E. coli strains to erythromycin (FIC ≤ 0.5). Another synergistic effect between tetracycline and cinnamaldehyde was observed when tested against E. coli ATCC 23739 (FIC = 0.3). Cinnamaldehyde synergistically and additively reduced the MIC of novobiocin when tested against ATCC 23739 and 02:0627 (FIC ≤ 0.5) or 8WT (FIC = 1), respectively, suggesting that E. coli strains may respond differently to challenge by the cinnamaldehyde-novobiocin combination. With all strains, cinnamaldehyde was not effective at reducing the MIC value of bacitracin. Findings of this study suggest that cinnamaldehyde may be used in combination with several antibiotics to enhance susceptibility of drug resistant E. coli.     

Selective hydrogenation of cinnamaldehyde over Raney cobalt catalysts modified with salts of heteropolyacids

The hydrogenation of cinnamaldehyde to cinnamyl alcohol was carried out over Raney cobalt catalysts modified by Cu_3/2PMo₁₂O₄₀. It was found that the conversion of cinnamaldehyde decreases substantially with increases in the amount of Cu_3/2PMo₁₂O₄₀ deposited on Raney cobalt catalysts. The maximum yield of cinnamyl alcohol varies with the amount of deposited Cu_3/2PMo₁₂O₄₀. The more the deposited modifier, the higher the attainable maximum yield of cinnamyl alcohol. With 2.8% Cu_3/2PMo₁₂O₄₀ modified Raney cobalt, the selectivity for cinnamyl alcohol does not change with reaction temperature and reaction time. Thus, it is likely that the selectivity of ca. 80% for cinnamyl alcohol represents a specific value which is related to the nature of the surface modifier, Cu_3/2PMo₁₂O₄₀. The influences of the heteropolyanions and the competitive cations on the conversion and the selectivity were also investigated. It was found that copper salts of different heteropolyacids acting as the modifier of the catalyst bring about different enhancements in the selectivity for cinnamyl alcohol. The order of enhancement of selectivity in terms of heteropolyacid anion is PMo₁₂O³⁻₄₀>SiMo₁₂O⁴⁻₄₀>PW₁₂O³⁻₄₀. There is little difference in selectivity by modification with (NH₄)₆Mo₇O₂₄ and Cu₂SiMo₁₂O₄₀. Raney cobalt catalyst modified by different 12-molybdophosphate containing cations of alkali, alkaline earth and transition metals gives a similar selectivity of about 75%. Among all of the 12-molybdophosphates, that containing the cation Cu²⁺ is the best in improving the selectivity of the catalysts. A selectivity as high as 83% was attained when an amount of 2.8% Cu_3/2PMo₁₂O₄₀ was deposited on the catalyst.     

肉桂醛微胶囊的制备工艺

研究了以阿拉伯树胶和麦芽糊精为壁材,喷雾干燥制备微胶囊化肉桂醛的工艺条件,探讨了壁材组成、乳化剂用量、固形物浓度,芯壁化,进风温度、进料速度、喷射压力等对微胶囊化效果的影响,经过正交试验,确定了最佳工艺条件。     

Nanoencapsulation and immobilization of cinnamaldehyde for developing antimicrobial food packaging material

Use of antimicrobial coatings on food packaging is one of the important technologies of active packaging for improving food safety. There is growing demand for natural antimicrobials because of fear of adverse health effects of synthetic preservatives. The objectives of this study were to compare antibacterial properties of free and nanoencapsulated cinnamaldehyde in solution; polylactic acid (PLA) surfaces cast with cinnamaldehyde; and glass and PLA surfaces coated with cinnamaldehyde nano-liposomes. Cinnamaldehyde was nano-encapsulated by lipid bilayers of polydiacetylene – N-hydroxysuccinimide (PDA–NHS) nano liposomes and immobilized on glass slides and PLA films. Glass surfaces immobilized with nano-encapsulated cinnamaldehyde showed significant antibacterial activity against Escherichia coli W1485 and Bacillus cereus ATCC 14579, with reductions of 2.56 log₁₀ CFU/ml and 1.59 log₁₀ CFU/ml respectively in 48 h. PLA films cast with cinnamaldehyde also showed significant antibacterial activities against E. coli W1485 (2.01 log₁₀ CFU/ml reduction) and B. cereus (4.81 log₁₀ CFU/ml reduction). However, when the liposomal encapsulated cinnamaldehyde was immobilized on PLA films, it did not show any antibacterial activity. Glass surfaces coated with nano-encapsulated cinnamaldehyde may be used as an active packaging material in preserving liquid foods; however, further study is required to improve antimicrobial activities of PLA surfaces.     

Influence of textural properties of activated carbons on Pd/carbon catalysts synthesis for cinnamaldehyde hydrogenation

A set of microporous carbons have been used to prepare Pd/carbon catalysts. The properties of the raw materials have been determined in terms of texture and surface chemistry. A deposition precipitation method has been employed to prepare the final catalysts, leading to well-dispersed palladium particles. The influence of the textural properties as well as the surface chemistry properties has been studied and a correlation was found between the surface in the pores of the support and the Pd dispersion. The chemistry surface properties of the Pd/carbon catalysts were found similar, despite differences in the case of the starting raw materials. The hydrogenation of cinnamaldehyde has been studied and the results obtained favourably compare with those already published. Turnover frequencies were similar whatever the catalyst. High selectivities close to 90% in hydrocinnamaldehyde were obtained at 90% conversion.