Huaixiang Tian

Inhibition of citral degradation by oil-in-water nanoemulsions combined with antioxidants.

The aim of the present study was to investigate the effects of oil-in-water (O/W) nanoemulsions combined with six different natural antioxidants on the stability of citral. Acidic emulsions (lecithin-stabilized palm kernel lipid in pH 3 buffer) containing 1000 ppm citral and 1000 ppm antioxidants (black tea extract, ascorbic acid, naringenin, tangeretin, β-carotene, and tanshinone) were stored at 25 and 50 °C, respectively. The emulsions with and without antioxidants were analyzed by solid phase microextraction gas chromatography (SPME-GC) to monitor the degradation process of citral and the formation of different off-flavor compounds, such as α,p-dimethylstyrene and p-methylacetophenone. The results suggested that encapsulation of citral in emulsions and the addition of the appropriate antioxidants (β-carotene, tanshinone, and black tea extract) could greatly enhance citrals chemical stability during storage.

Stability of Citral in Emulsions Coated with Cationic Biopolymer Layers

Multilayer emulsions containing citral were prepared by the layer-by-layer deposition technique based on the electrostatic interaction between negatively charged emulsion droplets and two positively charged biopolymer coatings, chitosan (CS) and ε-polylysine (EPL). The optimum concentrations of both CS and EPL were determined through the ζ-potential and particle size measurements and were found to be 1.5 mg/mL for CS and 6 mg/mL for EPL. Quartz crystal microbalance with dissipation monitoring (QCM-D) was conducted to monitor the binding between emulsion droplets and cationic polymers, and our results proved the existence of strong interactions between emulsions and the cationic polymer coatings. The stability of citral and the production of the off-flavor compounds were analyzed by solid-phase microextraction gas chromatography (SPME-GC). The results suggested that the addition of the cationic CS interfacial layer was effective in improving the stability of citral during storage.

Multivariate Classification of Cherry Wines Based on Headspace Solid Phase Microextraction and Gas Chromatography-Mass Spectrometry of Volatile Compounds

Headspace solid phase microextraction and gas chromatography-mass spectrometry was applied for cherry wine volatile analysis. Multivariate statistical analyses were used to track the influence of cultivar, fermentation method, wine type, vintage, and origin on the aroma of cherry wine. The major compounds in cherry wines are isoamylol, ethyl acetate, benzyl alcohol, benzaldehyde, and diethyl succinate. The principal component analysis results showed that classifying cherry wines by gas chromatography-mass spectrometry was highly related to fermentation methods and wine types. The agglomerative hierarchical clustering result indicated fermentation method has a greater effect on classification of cherry wines than other factors.

Comparison of volatile components in Chinese traditional pickled peppers using HS–SPME–GC–MS, GC–O and multivariate analysis

Volatile compounds of Chinese traditional pickled peppers (CTPPs) were extracted by solid-phase micro-extraction (SPME) and analysed by gas chromatography–mass spectrometry (GC–MS) and gas chromatography–olfactometry (GC–O) to visually compare their volatile compositions by applying principal component analysis (PCA). A total of 67 volatile components were identified by GC–MS, including 7 acids, 6 alkanes, 14 alcohols, 9 esters, 11 terpenes, 3 aldehydes, 5 ketones, 7 phenols and 5 miscellaneous compounds, tentatively identified or identified by comparing with mass spectra and retention indices of the standards or from literature. Of 45 volatile compounds detected in the sniffing port of GC–O, the majority of odour-active components included acetic acid, 2-ethyl phenol, L-linalool, tridecane, butyl butanoate, δ-3-carene. The individual concentrations of the volatile compounds such as acetic acid, ethanol, 1-propanol, L-linalool, hexyl 2-methyl butyrate and hexyl pentanoate corresponded well to the intensities of related attributes in the correlation analysis. Due to their high concentration level and low threshold value, these compounds played an important role in the final aromatic profile of the pickled peppers. The differences in flavours were observed by applying PCA to GC–MS data sets. From the PCA results, samples were primarily separated along the first principal component.

Development of a solid phase microextraction protocol for the GC-MS determination of volatile off-flavour compounds from citral degradation in oil-in-water emulsions.

The conditions for headspace solid phase microextraction (HS-SPME) analysis of volatile off-flavour compounds in citral emulsion were determined. Type of SPME phase (65 μm PDMS/DVB, 100 μm PDMS and 75μm CAR/PDMS), adsorption temperature and salt concentration were significant factors affecting total peak area in the gas chromatogram and optimised in one factor experiments. Then, adsorption temperature (30-50°C), adsorption time (20-40 min), and salt concentration (0-6M) were studied to develop HS-SPME condition for obtaining the highest extraction efficiency. PDMS/DVB in 65 μm was the optimum fiber because of high adsorption efficiency and good reproducibility. The optimal condition was adsorption at 50°C for 40 min and 6M salt added to sample. Good Linearity, high recovery, good reproducibility and low limit of detection (LOD) for all off-odour compounds according to the optimised SPME conditions indicated that the SPME procedure was applicable for the analysis of the degraded citral products in headspace volatile of emulsion.

Chemical Composition of Essential Oil from the Peel of Chinese Torreya grandis Fort

The composition of the peel essential oil of Torreya grandis fort obtained by cold pressing and steam distillation was determined by GC and GC/MS. 62 constituents accounting for 99.6% of the total pressed oil were identified while 59 compounds accounting for 99.4% of the steam distilled oil were identified. Limonene (35.6–37.1%), α-pinene (20.1–24.1%), and δ-carene (3.3–3.9) were the major constituents. Others include γ-carene (3.8-3.9%), germacrene D (2.5–2.9%), and β-farnesene (2.7-2.8%).

Preparation and characterization of citral-loaded solid lipid nanoparticles

Citral-loaded solid lipid nanoparticles (citral-SLNs) were prepared via a high-pressure homogenization method, using glyceryl monostearate (GMS) as the solid lipid and a mixture of Tween 80 (T-80) and Span 80 (S-80) at a weight ratio of 1:1 as the surfactant. The microstructure and properties of the citral-SLNs were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The chemical stability of citral in the citral-SLNs was analyzed by solid-phase microextraction gas chromatography (SPME-GC). The GC results showed that 67.0% of the citral remained in the citral-SLN suspensions after 12 days, while only 8.22% remained in the control. Therefore, the encapsulation of citral in the solid lipid can enhance its stability in acidic surroundings.

Comparison of Intensities and Binary Interactions of Four Basic Tastes between an Electronic Tongue and a Human Tongue

For detection of single taste intensities and binary interactions using an electronic tongue (E-tongue) and the human tongue (H-tongue), the 4 basic flavor substances of sucrose, caffeine, citric acid, and sodium chloride were used. A linear fit was performed using response values of the E-tongue and concentrations of the basic tastes. The taste intensity of the E-tongue was positively correlated with sour and salty substances, but negatively correlated with sweet and bitter substances. All taste intensities were positively correlated with the 4 flavor substances using the H-tongue. A mathematical model of the 4 taste substances on both the E-tongue and H-tongue exhibited a semi-logarithmic form. There were synergistic, dampening, or offset effects on the taste intensity of each flavor substance in binary systems. H-tongue and E-tongue results were consistent for sweet/bitter and salt/sour interactions. H-tongue and E-tongue results were contradictory for salt/sweet and sweet/sour interactions.

Recent patents on nano flavor preparation and its application.

Nano flavor preparation and its application have been reviewed in this paper. Nano flavor could be prepared by physical methods such as spray drying with microfluidization and ultrasonication, physical adsorption and so on, chemical methods such as complex formation, nano-sized self-structured liquid, and nano emulsification and so on. Different preparation technology could produce nano particles with different physical properties, thus they could be used in different occasions such as food, drug, cosmetics and so on. The article presents some promising patents on nano flavor preparation and its application.

Role of lactic acid bacteria on the yogurt flavour: A review

ABSTRACT Considerable knowledge has been accumulated on the lactic acid bacteria (LAB) that affect the aroma and flavour of yogurt. This review focuses on the role of LAB in the production of flavour compounds during yogurt fermentation. The biochemical processes of flavour compound formation by LAB including glycolysis, proteolysis, and lipolysis are summarised, with some key compounds described in detail. The flavour-related activities of LAB mostly depend on the species used for yogurt fermentation, and some strategies have been developed to obtain more control of the flavour-forming process. Metabolic engineering can be a powerful tool to reroute the metabolic flux towards the efficient accumulation of the desired flavour compounds with the knowledge of the complex network of flavour-forming pathways and the availability of genetic tools. Further progress made in the omics-based techniques and the use of systems biology approaches are needed to fully understand, control, and steer flavour formation in yogurt fermentation processes.