Dynamic changes of bacteria and screening of potential spoilage markers of lamb in aerobic and vacuum packaging.

Microorganisms proliferate, consume nutrients, and produce many undesired metabolites, which are the main reason for the spoilage of fresh meat. Screening spoilage markers is of great significance for characterizing the freshness of fresh meat. At present, there are few studies on the volatile spoilage markers (VSMs) of lamb and their relationship with bacteria. In this study, the spoilage evolution of lamb was evaluated by multiple indicators. The changes of bacteria and volatile organic compounds (VOCs) in aerobic-packaged (AP) and vacuum-packaged (VP) lamb were measured by 16S next-generation sequencing (NGS) and headspace solid-phase microextraction (HS-SPME)-gas chromatography-mass spectrometry (GC-MS) respectively. The potential VSMs were also screened. Results showed that the shelf life of AP lamb at 4 °C was less than 10 d and VP lamb was less than 28 d. Pseudomonas was the dominant bacteria in AP lamb, while Latilactobacillus and Lactococcus were the dominant bacteria in VP lamb. Several VOCs could be recommended as potential spoilage markers, including 1-octen-3-ol, 1-hexanol, nonanal, methoxy-phenyloxime, 2,3-octanedione, acetoin and 1-pentanol for AP lamb; acetoin, 1-hexanol, 2,3-octanedione, hexanoic acid, 1-octen-3-ol, nonanal, hexanal and 2,3-octanediol for VP lamb. This study can provide information for characterizing and predicting the freshness of fresh lamb.

Anti-leishmanial activity and identification of chemical constituents of Scrophularia striata essential oil by head space solid phase micro extraction gas chromatography mass spectrometry (HS-SPME GC-MS) / Actividad anti-leishmanial e identificación de componentes químicos del aceite esencial de Scrophularia striata mediante microextracción en fase sólida en el espacio de cabeza seguido de cromatografía gaseosa acoplada a espectrometría de masas (HS-SPME GC-MS)

The aim of the present study was to determine the main constituents of Scrophularia striata essential oil and to evaluate in vitro effect of essential oil on Leishmania tropica and Leishmania major promastigotes and axenic amastigotes. Chemical constituents of the extracted essential oil were separated by headspace solid-phase microextraction (HS-SPME) equipped with a PDMS/DVB fiber. The fiber was injected to gas chromatogram- mass spectroscopy (GC-MS) to determine their identity. Finally, after exposure of parasites to different concentrations of water soluble fraction of essential oil, viability of promastigotes and axenic amastigotes were investigated. Based on the HS-SPME results, 47 compounds representing 95.6% of the total oil, were identified in essential oil. Essential oil analysis showed that nonane (19.7%), α-terpineol (17.4%) and linalool (10.2%) were the most abundant compounds. This study indicates that water soluble fraction of S. striata essential oil has promising anti-leishmanial activity.

El objetivo del presente estudio fue determinar los principales componentes del aceite esencial de Scrophularia striata y evaluar el efecto in vitro del aceite esencial en promastigotes y amastigotes axénicos de Leishmania tropica y Leishmania major. Los componentes químicos del aceite esencial extraído se separaron mediante microextracción de fase sólida en el espacio superior (HS-SPME) equipado con una fibra PDMS/DVB. Para determinar su identidad la fibra se inyectó en un cromatógrafo de gases acoplado un espectrómetro de masas (GC-MS). Finalmente, después de la exposición de los parásitos a diferentes concentraciones de fracción soluble del aceite esencial en agua, se investigó la viabilidad de los promastigotes y los amastigotes axénicos. En base a los resultados de HS-SPME, se identificaron 47 compuestos que representan el 95.6% del aceite total en el aceite esencial. El análisis de aceites esenciales mostró que el nonano (19.7%), el α-terpineol (17.4%) y el linalol (10.2%) fueron los compuestos más abundantes. Este estudio indica que la fracción soluble en agua del aceite esencial de S. striata tiene una actividad antileishmanial prometedora.

Volatile organic compounds associated with Plasmodium falciparum infection in vitro.

BACKGROUND: In order to identify new ways to prevent transmission of vector-borne diseases such as malaria, efforts have been made to understand how insects are attracted to humans. Vector-host interaction studies have shown that several volatile compounds play an important role in attracting mosquitoes to human targets. A headspace solid-phase micro-extraction/gas chromatography-mass spectrometry (HSPME GC-MS) analysis of the volatile organic composition of extracellular vesicles (EVs) and supernatants of ultracentrifugation (SNUs) was carried out in Plasmodium falciparum-infected cultures with high and low parasitemias. RESULTS: A list of 18 volatile organic compounds (VOCs) was obtained from the EVs of both infected and uninfected RBCs with 1,2,3-Propanetriol, diacetate (diacetin) increased in the infected EVs, regardless of the parasitemia of the culture. The supernatant analysis, however, gave off 56 VOCs, with pentane 2,2,4-trimethyl being present in all the SNUs of uninfected erythrocytes but absent from the parasite-infected ones. Standing out in this study was hexanal, a reported insect attractant, which was the only VOC present in all samples from SNUs from infected erythrocytes and absent from uninfected ones, suggesting that it originates during parasite infection. CONCLUSIONS: The hexanal compound, reportedly a low-level component found in healthy human samples such as breath and plasma, had not been found in previous analyses of P. falciparum-infected patients or cultures. This compound has been reported as an Anopheles gambiae attractant in plants. While the compound could be produced during infection by the malaria parasite in human erythrocytes, the A. gambiae attraction could be used by the parasite as a strategy for transmission.