Pt-Re/rGO bimetallic catalyst for highly selective hydrogenation of cinnamaldehyde to cinnamylalcohol

In the present work, a series of Pt-based catalysts, alloyed with a second metal, i.e., Re, Sn, Er, La, and Y, and supported on activated carbon, ordered mesoporous carbon, N-doped mesoporous carbon or reduced graphene oxide(rGO), have been developed for selective hydrogenation of cinnamaldehyde to cinnamylalcohol. Re and rGO were proved to be the most favorable metal dopant and catalyst support, respectively. Pt_(50) Re_(50)/rGO showed the highest cinnamylalcohol selectivity of 89% with 94% conversion of cinnamaldehyde at the reaction conditions of 120 °C, 2.0 MPaH_2 and 4 h.     

Encapsulation of cinnamon and thyme essential oils components (cinnamaldehyde and thymol) in β-cyclodextrin: Effect of interactions with water on complex stability

Thymol and cinnamaldehyde formed inclusion complexes with β-cyclodextrin (β-CD) upon mixing the components in aqueous media and subsequent freeze–drying, as confirmed by differential scanning calorimetry. The samples were stored at constant relative humidities (RH) from 22% to 97%, at 25 °C. The release of encapsulated compounds was determined following the melting enthalpy of each guest. Water sorption isotherms for β-CD and the complexes showed constant and low water sorption at RH < 80%, then the uptake of water increased abruptly. The amount of sorbed water at each RH was smaller for the complexes than for β-CD. The guest molecules displaced water molecules from inside the cavity of β-CD. No thymol or cinnamaldehyde release was detected at RH < 84%, and it increased abruptly from 84% RH, coincidentally with the abrupt increase of sorbed water. Water sorption significantly affects β-CD complexes stability, which is thus governed by the shape of the water sorption isotherm.     

Effects of gamma radiation,individually and in combination with bioactive agents,on microbiological and physicochemical properties of ground beef

Effects of gamma irradiation (2 kGy) on microbiological and physicochemical properties of ground beef were investigated individually or in combination with bioactive compounds consisting of cinnamaldehyde, ascorbic acid, and sodium pyrophosphate decahydrate. Meat samples were mixed with cinnamaldehyde (1.47%, w/w), cinnamaldehyde plus ascorbic acid (0.5%, w/w), or cinnamaldehyde plus sodium pyrophosphate decahydrate (0.1%, w/w), followed by irradiation at a dose of 2 kGy. Microbiological and physicochemical properties of samples were analyzed. The results demonstrated that combined treatments using irradiation and bioactive compounds could significantly decrease the microbial load of meat samples compared with that of the untreated control samples. Moreover, the combined treatments did not cause any significant changes in physical or chemical properties of meat samples. Irradiation, both with and without cinnamaldehyde treatment, caused significant increases in concentrations of thiobarbituric reactive substances and peroxide in treated samples, compared with the concentrations of these substances in the control samples; however, in the presence of ascorbic acid, the pro-oxidative effect of irradiation treatment on ground beef was overcome.     

Effects of cinnamaldehyde on Escherichia coli and Staphylococcus aureus membrane

Gram-negative Escherichia coli (ATCC 8735) and Gram-positive Staphylococcus aureus (ATCC 3101) were selected as model bacteria to determine the antimicrobial mechanism of cinnamaldehyde. Several techniques were utilized to investigate the effects of cinnamaldehyde on food-borne bacterial membranes. The ultraviolet (UV) absorption and electrical conductivity of the culture supernatant were used to determine membrane integrity. β-Galactosidase activity was determined to detect inner membrane permeability. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed to observe bacterial morphology. Samples from both strains exposed to cinnamaldehyde showed higher UV absorptions, conductivity values, and β-Galactosidase activities compared with the control group and displayed a rapid rise trend. Thereafter, the values stabilized at a relatively steady state. SEM shows that treated E. coli and S. aureus cell samples exhibited rough cell membranes with particulate matter, and some of the S. aureus cells split due to deep wrinkle formation and distortion, unlike the control group. TEM shows that the bacteria treated with cinnamaldehyde exhibited numerous abnormalities, including cytoplasmic membrane separation from the cell wall, cell wall and cell membrane lysis, cytoplasmic content leakage, cytoplasmic content polarization, cell distortion, and cytoplasmic content condensation. These results indicate that bacterial cell morphology, membrane integrity, and permeability are damaged when the E. coli and S. aureus cells are exposed to the minimum inhibitory concentrations of cinnamaldehyde (0.31 mg/mL). In addition, the higher the cinnamaldehyde concentration, the more serious the bacterial membrane damage is.     

Effects of Operating Parameters on the Cinnamaldehyde Content of Extracted Essential Oil Using Various Methods

Supercritical fluid extraction (SFE) of essential oils from commercial cinnamon bark was compared with essential oils that were obtained by hydrodistillation. Effects of operating parameters (pressure, temperature and extraction time of SFE) on the extraction yield and the composition of the extracted volatile oil were studied. Moreover, in the hydrodistillation process, the effect of the pH of the solvent on the concentration of cinnamaldehyde in the extracted volatile oil was studied. The maximum yield of extract in the SFE process is about 7.8 % at 70 °C and 240 bar. The maximum concentration of cinnamaldehyde in the SFE process was obtained at 70 °C and 160 bar, and the maximum concentration of this component in hydrodistillation was achieved at pH = 4.1.     

Pt and Pt-alloy catalysts and their properties for the liquid-phase hydrogenation of cinnamaldehyde

The selective hydrogenation of ,β-unsaturated aldehydes to the corresponding unsaturated alcohol is not only of general interest in fine chemical and pharmaceutical intermediate production but also of specific relevance to the perfume and flavouring industries. A number of Pt/graphite catalysts have been prepared with metal loadings in the range 5–10 wt.% metal on graphite and with added cobalt in the composition range 5–99.5 mol%. These catalysts have been characterised using temperature programmed reduction (TPR) and have been compared with a commercial 5% (w/w) Pt/graphite catalyst for the hydrogenation of cinnamaldehyde in toluene and biphasic toluene/aqueous solutions containing a range of bases or potassium based salts. The reactions were carried out in a stirred reactor in the pressure range 4–11 bar absolute, in the temperature range 298–373 K, and with the concentration of cinnamaldehyde in the range 0.038–0.303 kmol/m³. The presence of strong bases was found to enhance both catalyst activity and selectivity to cinnamyl alcohol.     

Principal phenolic phytochemicals and antioxidant activities of three Chinese medicinal plants

The principal antioxidant components and content of cinnamon (Cinnamomum cassia), turmeric (Curcuma longa) and golden thread (Coptidis rhizoma) extracts were determined using high performance liquid chromatography (HPLC) with UV detection. In general, C. cassia, C. longa and C. rhizoma extracts from domestic Taiwan were rich in cinnamaldehyde, curcumin, and berberin, respectively. The contents of cinnamaldehyde, curcumin, and berberin in the acetone extracts were 1911, 2029, and 840 mg l⁻¹, respectively. The Folin–Ciocalteu method was used to measure the total phenolic concentrations of extracts, which had the content of 9.6 (C. cassia), 2.6 (C. longa), and 4.3 (C. rhizoma) mM l⁻¹. In addition, DPPH radical-scavenging, ferric-reducing antioxidant power (FRAP), and ferric thiocyanate (FTC) assays were employed to measure antioxidant activities. The C. cassia fresh extracts had higher antioxidant activities which were 84–90% (DPPH), 17–33 μmol l⁻¹ (FRAP), and 53–82% (FTC). The activities of C. longa fresh extracts were 22–44% (DPPH), 7–11 μmol l⁻¹ (FRAP), and 53–81% (FTC) while C. rhizoma were 53–64% (DPPH), 18–26 μmol l⁻¹ (FRAP), and 59–82% (FTC).     

肉桂醛的防霉效果及在月饼中的应用研究

市售月饼样品840份,在对其进行霉菌计数分析的基础上,对其优势霉菌进行了分离鉴定。从市售月饼中分离到常见霉菌主要有青霉属、曲霉属、毛霉、根霉、芽枝霉、镰刀菌等,其中优势霉菌为青霉属和曲霉属的霉菌,分别占分离总数的42%和37%。采用平板法测定了肉桂醛对分离到的6种霉菌的抗菌活性,结果表明其对青霉和曲霉的最小抑菌浓度分别为6mg/kg和12mg/kg。将染有10mg和20mg肉桂醛的纸片(2cm×2cm)和100g染有0.5ml青霉和曲霉菌混合孢子悬液(每毫升含有回收菌量约103个孢子)的月饼样品置于同一包装中,置28℃下培养观察,结果对照组试验第2d月饼就发生霉变,而试验组观察20d尚未发生霉变现象。     

Influence of Disperse Phase Characteristics on Stability, Physical and Antimicrobial Properties of Emulsions Containing Cinnamaldehyde

Cinnamaldehyde was delivered in emulsion form using Acetem 90-50K as a carrier and Tween 60 as emulsifier. Cinnamaldehyde interacted with Acetem 90-50K by forming H-bonds. The effect of disperse phase characteristics on storage stability, physical and antimicrobial properties was investigated. A storage test of emulsions was carried out for 15 days at two temperatures (22 and 4 °C). Emulsions and nano-emulsions showed higher stability at 22 °C than at 4 °C. Nano-emulsions displayed excellent stability versus creaming and coalescence after 15 days storage at 22 °C (z-avg <100 nm). Physical properties were greatly affected by droplet size and concentration. Emulsions became less viscous, more transparent and darker as the droplet size or concentration decreased. The antimicrobial activity was measured against Listeria monocytogenes and Escherichia coli. Escherichia coli was highly resistant to cinnamaldehyde compared to L. monocytogenes. Incubation with cinnamaldehyde at 2.5 mM caused the complete inactivation of L. monocytogenes after 1 day and of E. coli after 9 days. There was no difference in the antimicrobial effect of cinnamaldehyde due to different droplet sizes (~80 and ~5,000 nm).     

Acaricidal activity of cinnamaldehyde and its congeners against Tyrophagus putrescentiae (Acari: Acaridae)

The acaricidal activity of cinnamaldehyde and its 11 congeners against adults of Tyrophagus putrescentiae was examined using direct contact application and fumigation methods and compared with that of benzyl benzoate, N,N-diethyl-m-toluamide (DEET) and dibutyl phthalate. On the basis of 24 h LD₅₀ values, the compound most toxic to T. putrescentiae was cinnamyl acetate (0.89 μg/cm²) followed by cinnamaldehyde (1.12 μg/cm²), benzaldehyde (1.93 μg/cm²), 3-phenylpropionaldehyde (2.08 μg/cm²), cinnamyl alcohol (2.12 μg/cm²), salicylaldehyde (2.75 μg/cm²), and (E)-2-hydroxycinnamic acid (4.32 μg/cm²). These compounds were more potent than benzyl benzoate (10.03 μg/cm²), DEET (13.39 μg/cm²) and dibutyl phthalate (12.87 μg/cm²). Very low activity (<60 μg/cm²) was observed with cinnamic acid and (E)-4-hydroxycinnamic acid. Moderate activity was obtained from cinnamic acid methyl ester, (E)-3-hydroxycinnamic acid and 4-hydroxybenzaldehyde. These results indicate that hydrophobicity appears to play a crucial role in T. putrescentiae toxicity whereas a conjugated double bond and a length of CH chain outside the ring seem not to be implicated. In a fumigation test with T. putrescentiae adults, (E)-cinnamaldehyde, cinnamyl alcohol and salicylaldehyde were much more effective in closed containers than in open ones, indicating that the mode of delivery of these compounds was largely due to action in the vapour phase. Natural and synthetic congeners of (E)-cinnamaldehyde merit further study as potential T. putrescentiae control agents.