Low-temperature headspace-trap gas chromatography with mass spectrometry for the determination of trace volatile compounds from the fruit ofLycium barbarumL

Sensory-Guided Establishment of Sensory Lexicon and Investigation of Key Flavor Components for Goji Berry Pulp

Many customers prefer goji berry pulp, well-known for its high nutritional content, over fresh goji berries. However, there is limited research on its sensory lexicon and distinctive flavor compounds. This study focused on developing a sensory lexicon for goji berry pulp and characterizing its aroma by sensory and instrumental analysis. Sensory characteristics of goji berry pulp were evaluated by our established lexicon. A total of 83 aromatic compounds in goji berry pulp were quantified using HS-SPME-GC-Orbitrap-MS. By employing OAV in combination, we identified 17 aroma-active compounds as the key ingredients in goji berry pulp. Then, we identified the potentially significant contributors to the aroma of goji berry pulp by combining principal component analysis and partial least squares regression (PLSR) models of aroma compounds and sensory attributes, which included 3-ethylphenol, methyl caprylate, 2-hydroxy-4-methyl ethyl valerate, benzeneacetic acid, ethyl ester, hexanal, (E,Z)-2,6-nonadienal, acetylpyrazine, butyric acid, 2-ethylhexanoic acid, 2-methyl-1-propanol, 1-pentanol, phenylethyl alcohol, and 2-nonanone. This study provides a theoretical basis for improving the quality control and processing technology of goji berry pulp.

Headspace-Low Water Absorption Trap Technique: Analysis of Low-Abundance Volatile Compounds from Fresh Artemisia Annua L. with GC-MS

Conventional headspace (HS) method could not meet the requirement of analyzing low-abundance volatile compounds in high water content samples. A HS-low water absorption trap technique coupled with gas chromatography-mass spectrometry was introduced to remove the large amount of water vapor; therefore, the low-abundance volatile compounds could be detected with better analytical sensitivity. With this method, a total of 81 volatile compounds were identified from fresh Artemisia annua L. by mass spectral library search, retention index and accurate mass measurement, which could make the qualitative results more accurate and reliable. These compounds belonged to different species, including terpene, cycloparaffin, aliphatic aldehyde, aromatic ketone, aromatic aldehyde and so on. The 2,5,6-trimethyl-1,3,6-heptatriene (8.23%) was the most principal compound, followed by γ-muurolene (6.80%), β-caryophyllenea (6.24%), 1,8-cineol (5.76%), 2-carene (5.65%), borneol (5.57%), isocaryophyllene (4.91%), bornylene (4.78%), camphene (4.30%) and β-pinene (4.26%) as the main components. The results indicated that this method presents a great potential for the trace analysis of volatile compounds in complex high water content samples.

Goji Berries Supplementation in the Diet of Rabbits and Other Livestock Animals: A Mini-Review of the Current Knowledge

In the last decades, several nutraceutical substances have received great attention for their potential role in the prevention and treatment of different diseases as well as for their beneficial effects in promoting the health of humans and animals. Goji berries (GBs) are the fruit of Lycium barbarum and other species of Lycium, used in traditional Chinese medicine, and they have recently become very popular in the Occidental world because of their properties, such as anti-aging, antioxidant, anticancer, neuroprotective, cytoprotective, antidiabetic, and anti-inflammatory activities. These effects are essentially evaluated in clinical trials in humans; in experimental animal models, such as mice and rats; and in cell lines in in vitro studies. Only recently has scientific research evaluated the effects of GBs diet supplementation in livestock animals, including rabbits. Although studies in the zootechnical field are still limited and the investigation of the GB mechanisms of action is in an early stage, the results are encouraging. This review includes a survey of the experimental trials that evaluated the effects of the GBs supplementation on reproductive and productive performances, immune system, metabolic homeostasis, and meat quality principally in the rabbit with also some references to other livestock animal species. Evidence supports the idea that GB supplementation could be used in rabbit breeding, although future studies should be conducted to establish the optimal dose to be administered and to assess the sustainability of the use of GBs in the diet of the rabbit.

Development and optimization of a method for determining betaine and trigonelline in the fruits of Lycium species by using solid-phase extraction combined with high-performance liquid chromatography-diode array detector

Betaine is an essential nutrient for humans and a source of methyl donors for methionine and S-adenosylmethionine formation, and it is used as a biomarker for pharmacological activities and to evaluate the quality of Lycium species and common foods. However, because of its special structural features, poor ultraviolet-chromophore, and high polarity, the existing methods for betaine extraction and quantification cannot provide higher extraction efficiency, better sensitivity, or resolution degree. A simple, fast, and efficient high-performance liquid chromatography-diode array detector coupled with solid-phase extraction was adopted for simultaneous separation and quantification of betaine in four types of Lycium species. The results revealed that after degreasing with dichloromethane, extraction with 80% ethanol (pH adjusted to 1.0 with hydrochloric acid), and elution with aluminum oxide (OH^- form), the improvement in the average yield rate of betaine was thrice of that of the existing methods. In addition, trigonelline was identified as the interfering substance of betaine for the first time in Lycium species, and betaine and trigonelline were simultaneously separated and quantified. Furthermore, their chemical characteristics and content distribution in different Lycium species were carried out.

De novo characterization of the Goji berry (Lycium barbarium L.) fruit transcriptome and analysis of candidate genes involved in sugar metabolism under different CO2 concentrations

Goji berry (Lycium barbarum L.) is one of the important economic crops due to its exceptional nutritional value and medicinal benefits. Although reduced sugar levels in goji berry exposed to long-term elevated carbon dioxide (CO2) have been documented, the underlying molecular mechanisms remain unknown. The objective of this study was to explore the transcriptome of goji berry fruit under ambient and elevated CO2 concentrations and further to screen the differentially expressed genes (DEGs) for functions related to sugar metabolism. Fruit samples from goji berry exposed to ambient (400 μmol mol-1) and elevated (700 μmol mol-1) levels of CO2 for 120 days were analyzed for total sugar, carotenoid and flavone analysis. In this study, a reduction in total sugar and carotenoid levels in the fruits grown under elevated CO2 levels were observed. Fruit samples were also used to construct cDNA libraries using a HiSeqTM2500 platform. Consequently, 81,100 unigenes were assembled, of which 35,111 (43.3%) were annotated using various databases. Through DEGs analysis, it was found that 55 genes were upregulated and 18 were down-regulated in response to elevated CO2 treatment. Genes involved in the sugar metabolism and the related pathways were identified by Gene Ontology and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis. Furthermore, three genes, LBGAE (Lycium barbarum UDP-glucuronate 4-epimerase), LBGALA (Lycium barbarum alpha-galactosidase) and LBMS (Lycium barbarum malate synthase), associated with sugar metabolism were identified and discussed with respect to the reduction in the total sugar levels along with the enzymes acid invertase (AI), sucrose synthase (SS) and sucrose phosphate synthase (SPS) of the sucrose metabolism. This study can provide gene sources for elucidating the molecular mechanisms of sugar metabolism in the fruit of goji berry under elevated CO2.

Analysis of volatile profiles of green Hawai'ian coffee beans damaged by the coffee berry borer (Hypothenemus hampei)

BACKGROUND

The coffee berry borer (CBB), Hypothenemus hampei, is the most destructive insect pest of coffee globally, causing significant losses in yield and leading to 'off' flavors in damaged beans. Automated headspace sampling (AHS) and gas chromatography-mass spectrometry (GC-MS) were used to investigate changes in the volatile profiles of CBB-damaged green coffee beans. Green coffee from three coffee farms on the island of Hawai'i were sorted into three levels of CBB damage: non-damaged, slightly damaged (1-2 pinholes/bean), and heavily damaged (> 2 pinholes/bean).

RESULTS

Distinct differences were found between green coffee bean samples based on the amounts of eight prominent volatiles. The amount of CBB damage was particularly correlated with the amount of both hexanal and 2-pentylfuran. Principal component analysis showed clustering of non-damaged green beans, which did not overlap with the slightly or heavily damaged clusters. Good separation was also found between a mixture of 50% slightly damaged and non-damaged coffee. However, 20% slightly damaged and non-damaged coffee clusters showed strong overlap.

CONCLUSION

Understanding the effects of CBB damage on coffee flavor profiles is critical to quality control for this valuable agricultural product. The results of this study show that the volatile profiles of green coffee beans vary with CBB damage. With specific volatile profiles for CBB-damaged coffee identified, coffee samples can be tested in the lab, or potentially on the farm or in coffee mills, to identify high levels of CBB damage that may lead to off flavors and a reduction in product quality and value. © 2018 Society of Chemical Industry.

Qualitative analysis of Schizonepeta annua (Pall.) Schischk essential oil by gas chromatography-quadrupole time-of-flight mass spectrometry

In this study, a method for the qualitative analysis of small molecular compounds in Schizonepeta annua (Pall.) Schischk essential oil was established based on gas chromatography-quadrupole time-of-flight mass spectrometry. In addition to an automated search of the NIST library, the identification of oxygenated monoterpenes, phenolic esters, and phenolic compounds was achieved by two additional strategies. One strategy involved comparing the relative errors of accurate masses measured for ions in the experimental spectra with those calculated for fragments identified from the NIST database of candidate matches. The second strategy involved combination of the product ion scans and positive chemical ionisation spectra for structural elucidation. Overall, 95.45% of the total essential oil volatile chemical content of Schizonepeta annua (Pall.) Schischk was identified, with phenolic monoterpenes dominating.

Volatile changes in Hawaiian noni fruit, Morinda citrifolia L., during ripening and fermentation

BACKGROUND

Noni fruit (Morinda citrifolia L., Rubiaceae) has been used in traditional medicine throughout the tropics and subtropics and is now attracting interest in western medicine. Fermented noni juice is of particular interest for its promising antitumor activity. The present study collected and analyzed volatiles released at nine time intervals by noni fruit during ripening and fermentation using headspace autosampling coupled to gas chromatography-mass spectrometry.

RESULTS

Twenty-three noni volatiles were identified and relatively quantified. In addition to volatiles previously identified in noni, four novel volatile 3-methyl-2/3-butenyl esters were identified via the synthesis of reference compounds. Principle component analysis (PCA) and canonical discriminant analysis (CDA) were used to facilitate multidimensional pattern recognition. PCA showed that ripening noni fruit cluster into three groups, pre-ripe, fully ripe (translucent) and fermented, based on released volatiles. CDA could 83.8% correctly classify noni samples when all ripeness stages were analyzed and 100% when samples were classified into the three PCA groupings.

CONCLUSION

The results of the present study confirm the identities of 3-methyl-2/3-butenyl esters, both novel and previously identified, through the synthesis of reference compounds. These esters constitute a large percentage of the volatiles released by fully ripe and fermented noni and likely produced from the decomposition of noniosides, a group of unique glucosides present in the fruit. © 2017 Society of Chemical Industry.

Temperature-programmed multicapillary gas chromatograph microcolumn for the analysis of odorous sulfur pollutants

We report the fabrication and performance of a silicon-on-glass micro gas chromatography eight-capillary column based on microelectromechanical systems technology that is 50 cm long, 30 μm wide, and 300 μm deep. According to the theory of a gas chromatography column, an even gas flow among different capillaries play a vital role in the peak broadening. Thus, a flow splitter structure is designed by the finite element method through the comparison of the velocity distributions of the eight-capillary columns with and without splitter as well as an open tubular column. The simulation results reveal that eight-capillary column with flow splitters can receive more uniform flow velocity in different capillaries, hence decreases the peak broadening and in turn increases the separation efficiency. The separation experiment results show that the separation efficiency of about 22 000 plates/m is achieved with the chip column temperature programmed for analysis of odorous sulfur pollutants. This figure is nearly two times higher than that of the commercial capillary column coated the similar stationary phase. And the separation time of all the components in the microcolumn is less than 3.8 min, which is faster than the commercial capillary column.

Advanced development in phytochemicals analysis of medicine and food dual purposes plants used in China (2011-2014)

In 2011, we wrote a review for summarizing the phytochemical analysis (2006-2010) of medicine and food dual purposes plants used in China (Zhao et al., J. Chromatogr. A 1218 (2011) 7453-7475). Since then, more than 750 articles related to their phytochemical analysis have been published. Therefore, an updated review for the advanced development (2011-2014) in this topic is necessary for well understanding the quality control and health beneficial phytochemicals in these materials, as well as their research trends.