会东县不同品种块菌挥发性香气成分的GC-MS分析

挥发性香气成分是块菌品质的重要指标,为探究不同品种块菌挥发性香气成分的差异,采用顶空固相微萃取结合气相色谱-质谱联用对挥发性成分进行分析,并采用相对气味活度值判定主体挥发性香气成分。结果表明：6 种块菌共鉴定出24 种挥发性成分,主要包括醇类、酮类、醛类、烯类等,6 种块菌中共有的挥发性成分为1-辛烯-3-醇、苯乙醛、反-2-辛烯醛。假凹陷块菌的主体挥发性香气成分为1-辛烯-3-醇和苯乙醛;夏块菌的主体挥发性香气成分为1-辛烯-3-醇、苯乙醛、反-2-辛烯醛、苯甲醛和己醛;印度块菌和会东块菌的主体挥发性香气成分为1-辛烯-3-醇;凹陷块菌的主体挥发性香气成分为1-辛烯-3-醇、苯乙醛、反-2-辛烯醛、己醛和3-辛酮;波氏块菌的主体挥发性香气成分为1-辛烯-3-醇、反-2-辛烯醛和3-辛酮。     

Starch,protein, glycoalkaloids,and <Emphasis Type="SmallCaps">l</Emphasis>-ascorbic acid content in tubers of genetically modified potato cv. Irga

Changes in contents of protein, starch, ash, l-ascorbic acid, and glycoalkaloids in tubers of 15 clones of cultivar Irga transformed with viral genome sequences in order to improve their resistance to a necrotic strain of potato virus Y (PVY^N) were investigated. The influence of modification type and year of cultivation on the contents of all chemical compounds examined for particular modified clones appeared to be irregular over the 3-year period of examination, and the clone of the best and stable content of chemical compounds was not found. Stable tendencies in the chemical compounds of tubers composed into groups and subgroups of clones representing the same modification type were not confirmed either. An essential stable decrease in glycoalkaloid content and an increase in starch content (compared with parental cultivar Irga) were found in almost all genetically modified clones. Glycoalkaloid content in green tubers of modified clones was usually (except three clones) higher than this for parental cultivar Irga. Correlation between glycoalkaloid content and tuber size for all, normal and green tubers of selected clones and parental cultivar Irga was examined as well.     

Optimization of summer truffle aroma analysis by SPME: Comparison of extraction with different polarity fibres

The objective of the present investigation was the optimization of the extraction of volatile compounds of the summer truffle aroma (Tuber aestivum) by headspace solid-phase microextraction (HS-SPME) using fibres of different polarity able to provide complementary information. A response surface experimental design was applied considering three factors such as extraction temperature, equilibrium time and extraction time. Optimization was carried out using two fibres of different polarity (PDMS and CW/DVB) in order to obtain data about the profile of summer truffle aroma. The extracted compounds were analysed by gas chromatography with a flame ionization detector and by gas chromatography/mass spectrometry. The responses optimised were those related with the quality and intensity of the aroma such as the total area of the chromatogram. Results showed that the extraction temperature was statistically the most influential among the different factors studied; also, the polar fibre was able to extract higher amounts of total volatile compounds.     

Runoff Efficiency and the Technique of Micro-water Harvesting with Ridges and Furrows,for Potato Production in Semi-arid Areas

A field study was conducted to determine runoff efficiency and the effects of different ridge: furrow ratios and ridge-covering materials on tuber yield, soil moisture storage and water use efficiency (WUE) in the ridge and furrow micro-water harvesting system in a dry semi-arid region of China, during two consecutive years of 2002 and 2003. The average runoff efficiency of ridges with compacted soil (SR) was very low (24.6–28.8%) compared to that of ridges covered with plastic film (MR) (91.1–94.3%). The minimal rainfall necessary to produce runoff was 2.76–2.78 mm for SR, only 0.23–0.47 mm for MR. The field experiments using potato as an indicator crop showed that tuber yields in the MR system were significantly higher than that in the flat planting (control), with an average increase of 158.6–175.0% during 2 years. In the SR system, the average increase was valued of 14.9–28.4% during 2 years. Regression analysis between tuber yields and ridge widths indicated the optimum ridge: furrow ratio for MR was 39: 60 cm in 2002 and 48: 60 cm in 2003 respectively. The WUE values of potato in MR were 1.50 times greater than that of the controls in 2002 and 1.62 times greater than the controls in 2003. No differences were found in the WUE between the SR and the controls on average of 2 years. Due to the different runoff efficiency between two ridge-covering materials and absence of runoff occurrence in the controls, the soil water content in the MR was higher than that in the SR, both of which were greater than the controls. With the soil crust development, the distribution of soil water at the bottom of the furrow, at the side of the furrow and at the top of the ridge, is similar between the SR and the MR.     

Analysis of headspace volatiles from entire black truffle (Tuber melanosporum)

A dynamic headspace analysis is employed for isolating aroma volatiles directly from entire black truffles (Tuber melanosporum). The qualitative analysis is carried out by gas chromatography-mass spectrometry. The formation of the major volatile compounds and their contribution to the final aroma impression is also discussed.     

Green Synthesis of Chromium Oxide Nanoparticles for Antibacterial,Antioxidant Anticancer,and Biocompatibility Activities

This study deals with the green synthesis of chromium oxide (Cr₂O₃) nanoparticles using a leaf extract of Abutilon indicum (L.) Sweet as a reducing and capping agent. Different characterization techniques were used to characterize the synthesized nanoparticles such as X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Energy-dispersive X-ray (EDX), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-VIS) spectroscopy. The X-ray diffraction technique confirmed the purity and crystallinity of the Cr₂O₃ nanoparticles. The average size of the nanoparticles ranged from 17 to 42 nm. The antibacterial activity of the green synthesized nanoparticles was evaluated against four different bacterial strains, E. coli, S. aureus, B. bronchiseptica, and B. subtilis using agar well diffusion and a live/dead staining assay. The anticancer activities were determined against Michigan Cancer Foundation-7 (MCF-7) cancer cells using MTT and a live/dead staining assay. Antioxidant activity was investigated in the linoleic acid system. Moreover, the cytobiocompatibility was analyzed against the Vero cell lines using MTT and a live/dead staining assay. The results demonstrated that the green synthesized Cr₂O₃ nanoparticles exhibited superior antibacterial activity in terms of zones of inhibition (ZOIs) against Gram-positive and Gram-negative bacteria compared to plant extracts and chemically synthesized Cr₂O₃ nanoparticles (commercial), but comparable to the standard drug (Leflox). The green synthesized Cr₂O₃ nanoparticles exhibited significant anticancer and antioxidant activities against MCF-7 cancerous cells and the linoleic acid system, respectively, compared to chemically synthesized Cr₂O₃ nanoparticles. Moreover, cytobiocompatibility analysis displayed that they presented excellent biocompatibility with Vero cell lines than that of chemically synthesized Cr₂O₃ nanoparticles. These results suggest that the green synthesized Cr₂O₃ nanoparticles’ enhanced biological activities might be attributed to a synergetic effect. Hence, green synthesized Cr₂O₃ nanoparticles could prove to be promising candidates for future biomedical applications.     

Volatile organic compounds from a Tuber melanosporum fermentation system

A total of 59 volatile organic compounds (VOCs) were identified from Tuber melanosporum fermentation: 53 from its fermented mycelia and 32 from the fermentation broth. Alcohol-derived compounds were predominant in both the fermentation mycelia and the broth, although long chain fatty acids and isoprenoids were, for the first time, also found in the mycelia. The intense wine bouquet properties of the broth arose from several specific flavor substances, including sulfur compounds, pyrazines, furans and jasmones. Comparing the VOCs identified in this work with those previously reported, our results are more similar to the composition of the Tuber fruiting-body than previous Tuber fermentations. The composition and accumulation of flavor volatiles (e.g., pyrazines, sulfur compounds, and esters) and major constituents (e.g., 3-methyl-1-butanol and 2-phenylethanol) in this fermentation were significantly influenced by the sucrose concentration in the medium. The obtained information could therefore be useful in applications to convert the flavors of truffle mycelia similar to those of the fruiting-body by optimising the fermentation process.     

Effects of electron-beam irradiation on the shelf life, microbial populations and sensory characteristics of summer truffles (Tuber aestivum) packaged under modified atmospheres

The effects of two doses of electron-beam irradiation (1.5 kGy and 2.5 kGy) on the microbial populations (total mesophilic aerobes, Pseudomonas genus, Enterobacteriaceae family, molds and yeasts) and sensory characteristics of Tuber aestivum packaged under modified atmospheres were monitored immediately after treatment, and weekly during 42 days of storage at 4 °C. Treatment with 1.5 and 2.5 kGy reduced the pseudomonads populations by 4.3 and 5.5 logs, respectively. Enterobacteriaceae counts decreased by 5.4 logs with the 1.5 kGy dose and counts below the detection limit (<1.0 log cfu/g) were obtained with the 2.5 kGy dose. Lactic acid bacteria and yeasts were less affected by the ionizing radiation treatments and they became the dominant microbial populations throughout storage with microbial counts up to 7.1 log cfu/g. The carbon dioxide levels inside the packages containing irradiated truffles were lower than those of the non-irradiated ones, suggesting a decrease in the respiration rate of the treated ascocarps. The treatments with 1.5 and 2.5 kGy e-beam did not negatively affect the sensory characteristics of truffles, but a visible superficial yeast growth was detected in truffles irradiated with 1.5 kGy at the end of their shelf life (day 28). Treatment with 2.5 kGy e-beam has prolonged the shelf life to 42 days, compared with 21 days for the untreated samples.     

Effects of electron-beam and gamma irradiation treatments on the microbial populations, respiratory activity and sensory characteristics of Tuber melanosporum truffles packaged under modified atmospheres

The effects of electron-beam or gamma irradiation (doses of 1.5 kGy and 2.5 kGy of either one) on the microbial populations, respiratory activity and sensory characteristics of Tuber melanosporum packaged under modified atmospheres were monitored immediately after treatment, and subsequently every seven days during 35 days of storage at 4 °C. Treatments with 1.5 and 2.5 kGy reduced the total mesophilic aerobes counts respectively by 4.3 and 5.6 log cfu/g for electron-beam treatment, and by 6.4 and 6.6 log cfu/g for gamma irradiation. Other microbial groups studied (Pseudomonas genus, Enterobacteriaceae family, lactic acid bacteria, mesophilic aerobic spores, molds and yeasts) were not detected after the treatments. A decrease in the respiratory activity was detected in all the irradiated batches, indicating that the carbon dioxide levels were lower and the oxygen levels higher than those of the non-irradiated ones. Two species of yeasts, Candida sake and Candida membranifaciens var. santamariae, survived the irradiation treatments and became the dominant microbial populations with counts of up to 7.0 log cfu/g. The growth of these microorganisms was visible on the surface of irradiated truffles from day 21 onwards, affecting the flavor and the general acceptability of the ascocarps. Moreover, a watery exudate was detected in the treated truffles from the third week onwards, so the application of irradiation treatments in doses equal to or above 1.5 kGy did not preserve the quality characteristics of T. melanosporum truffles beyond 28 days.     

Effect of antiviral genetical modification on softening of potato tubers during cooking

An investigation into the influence of genetical modification on potato tubers should include also an estimation of their technological usability. Potato tubers of 15 clones of cultivar Irga transformed with viral genome sequences in order to improve their resistance to a necrotic strain of potato virus Y (PVY^N) were examined. The effect of cooking on tissue texture, expressed by fracture stress (F) and strain (D), and elastic modulus (E) from a compression test, was investigated. Although the influence of the modification type appeared to be statistically significant but irregular in particular years of cultivation, a detailed statistical analysis (variance and discrimination analyses) did not confirm any repeatable nor statistically significant differences in F, D, and E over the three-years period of examinations. While the effect of cultivation year was unmistakable, the order of F, D, and E values for particular clones was not constant in the successive years. The lack of stable tendencies in average values of the mechanical parameters for both groups and subgroups of clones representing the same modification model was also found. The statistical analysis of the variability of mechanical parameters of raw and heat-treated potatoes measured during the three successive years enabled classifying Irga and its genetically-modified clones as similar and did not allow to distinguish clones of the quickest softening.