The electronic nose coupled with chemometric tools for discriminating the quality of black tea samples in situ

An electronic nose (E-nose), comprising eight metal oxide semiconductor (MOS) gas sensors, was used in situ for real-time classification of black tea according to its quality level. Principal component analysis (PCA) coupled with signal preprocessing techniques (i.e., time set value preprocessing, F1; area under curve preprocessing, F2; and maximum value preprocessing, F3), allowed grouping the samples from seven brands according to the quality level. The E-nose performance was further checked using multivariate supervised statistical methods, namely, the linear and quadratic discriminant analysis, support vector machine together with linear or radial kernels (SVM-linear and SVM-radial, respectively). For this purpose, the experimental dataset was split into two subsets, one used for model training and internal validation using a repeated K-fold cross-validation procedure (containing the samples collected during the first three days of tea production); and the other, for external validation purpose (i.e., test dataset, containing the samples collected during the 4th and 5th production days). The results pointed out that the E-nose-SVM-linear model together with the F3 signal preprocessing method was the most accurate, allowing 100% of correct predictive classifications (external-validation data subset) of the samples according to their quality levels. So, the E-nose-chemometric approach could be foreseen has a practical and feasible classification tool for assessing the black tea quality level, even when applied in-situ, at the harsh industrial environment, requiring a minimum and simple sample preparation. The proposed approach is a cost-effective and fast, green procedure that could be implemented in the near future by the tea industry.Ministry of Research, Technology and Higher Education of the Republic of Indonesia through a research scheme of PTUPT 2019 (Contract No. 2688/UN1.DITLIT/DIT-LIT/LT/2019). This work was also financially supported by strategic project UID/EQU/50020/2019—Associate Laboratory LSRE-LCM, strategic project PEst-OE/AGR/UI0690/2014–CIMO, strategic funding UID/BIO/04469/2019-CEB and BioTecNorte operation (NORTE-01-0145-FEDER-000004), all funded by European Regional Development Fund (ERDF) through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI)—and by national funds through FCT—Fundação para a Ciência e a Tecnologia I.P.info:eu-repo/semantics/publishedVersio

Optimization of electronic nose drift correction applied to tomato volatile profiling

This is a pre-print of an article published in Analytical and Bioanalytical Chemistry. The final authenticated version is available online at: https://doi.org/10.1007/s00216-021-03340-5E-noses can be routinely used to evaluate the volatile profile of tomato samples once the sensor drift and standardization issues are adequately solved. Short-term drift can be corrected using a strategy based on a multiplicative drift correction procedure coupled with a PLS adaptation of the component correction. It must be performed specifically for each sequence, using all sequence signals data. With this procedure, a drastic reduction of sensor signal %RSD can be obtained, ranging between 91.5 and 99.7% for long sequences and between 75.7 and 98.8% for short sequences. On the other hand, long-term drift can be fixed up using a synthetic reference standard mix (with a representation of main aroma volatiles of the species) to be included in each sequence that would enable sequence standardization. With this integral strategy, a high number of samples can be analyzed in different sequences, with a 94.4% success in the aggrupation of the same materials in PLS-DA two-dimensional graphical representations. Using this graphical interface, e-noses can be used to developed expandable maps of volatile profile similitudes, which will be useful to select the materials that most resemble breeding objectives or to analyze which preharvest and postharvest procedures have a lower impact on the volatile profile, avoiding the costs and sample limitations of gas chromatography

The role of the gut and the gastrointestinal microbiome in Parkinson’s disease

INTRODUCTION: Parkinson’s disease (PD) is a disabling and progressive neurodegenerative disorder that is increasing in prevalence with the aging and urbanisation of the global population. The mechanisms underlying PD pathogenesis and progression are incompletely understood. Improved clinical recognition of early and prodromal non-motor symptoms (NMS), namely gastrointestinal (GI) dysfunction, has focused research over the last two decades on the roles of the gut. More recently, the influences of the microbiota-gut-brain-axis (MGBA) in the development and progression of PD have become an intensive area of research. Studies have demonstrated an association between the GM and a variety of PD-related characteristics, identifying important impacts on levodopa metabolism by certain microbiota. Importantly, the effect of device-assisted therapies (DATs) on the GM and the robustness of microbiota compositional differences between PD patients and household controls (HCs) has not been well defined. The aims of this thesis were to 1) investigate GI dysfunction and nutritional patterns in PD, 2) determine if the GM is a biomarker of PD, and 3) investigate the temporal stability of the GM in PD patients receiving standard therapies and those initiating DATs. METHODS: 103 PD patients and 81 HCs were recruited and participants with PD were considered in two sub-cohorts; 1) PD patients initiating DAT; either Deep Brain Stimulation (DBS) (n=10), or levodopa-carbidopa intestinal gel (LCIG) (n=11), who had GM sampling from stool at -2, 0, 2 and 4 weeks around initiation of DAT and baseline, 6 and 12 months following DAT initiation, 2) 82 PD patients receiving standard PD therapies, who had GM sampling from stool at baseline, 6 and 12 months. Validated PD questionnaire metadata ascertaining motor characteristics and NMS, as well as nutritional data in the form of a Food Frequency Questionnaire, were collected for all participants at baseline, 6 and 12 months. Total DNA was isolated from stool before sequencing the V3-V4 region of 16S rRNA. Relative bacterial abundances, diversity measures, compositional differences and clinical-microbiome associations were determined, as well as developing predictive modelling to identify PD patients and assess disease progression. RESULTS: PD patients reported more prevalent and severe GI dysfunction, especially constipation, which was almost three-times more common compared to HC subjects, (78.6% vs 28.4%, p<0.001). PD patients had a higher intake of total carbohydrates (279 g/day vs 232 g/day; p=0.034), which was largely attributable to an increased daily sugar intake (153 g/day vs 119 g/day; p=0.003), particularly of free sugars (61 g/day vs 41 g/day; p=0.001). Significant GM compositional differences across several taxonomic levels were apparent between PD patients and HCs and associated with a number of PD motor and NMS features, as well as certain therapies. Predictive models to distinguish PD from HCs were developed considering global GM profiles, achieving an area under the curve (AUC) of 0.71, which was improved by addition of data on carbohydrate intake (AUC 0.74). Longitudinal analysis demonstrated persistent underrepresentation of known short-chain fatty acid producing bacteria in PD patients, particularly those concerned with butyrate production; Butyricicoccus, Fusicatenibacter, Lachnospiraceae ND3007 group and Erysipelotrichaceae UCG−003. Taxa differences observed over the short-term (four week) sampling period around DAT (DBS and LCIG) initiation, were not sustained at 6 and 12 months. Despite this, persistent longer-term overrepresentation of Prevotella was observed after DBS initiation, and a trend was found that was suggestive of overrepresentation of Roseburia after LCIG initiation. These results suggest that there may be variable shorter and longer-term DBS and LCIG influences on the GM, which are complex and multifactorial. PD progression analysis did not identify distinct persisting GM compositional differences between faster and slower progressing patients, although predictive modelling was strengthened by the consideration of nutritional data, specifically protein intake, and improved the predictive capacity for PD progression. CONCLUSION: This thesis demonstrates that there are numerous clinically significant associations between the gut, GM and PD. GI dysfunction is common, and carbohydrate nutritional intake appears to be different from the general population in PD. Persistent alterations of GM composition in PD compared to HCs were found. These findings provide support for the existence of disturbances of gut homeostatic pathways, which may disrupt intestinal barrier permeability and lead to gut leakiness, in the pathogenesis of PD. This thesis also highlights the potential to use the GM in the identification of PD and the characterisation of disease progression

Antioxidant and DPPH-Scavenging Activities of Compounds and Ethanolic Extract of the Leaf and Twigs of Caesalpinia bonduc L. Roxb.

Antioxidant effects of ethanolic extract of Caesalpinia bonduc and its isolated bioactive compounds were evaluated in vitro. The compounds included two new cassanediterpenes, 1α,7α-diacetoxy-5α,6β-dihydroxyl-cass-14(15)-epoxy-16,12-olide (1)and 12α-ethoxyl-1α,14β-diacetoxy-2α,5α-dihydroxyl cass-13(15)-en-16,12-olide(2); and others, bonducellin (3), 7,4’-dihydroxy-3,11-dehydrohomoisoflavanone (4), daucosterol (5), luteolin (6), quercetin-3-methyl ether (7) and kaempferol-3-O-α-L-rhamnopyranosyl-(1Ç2)-β-D-xylopyranoside (8). The antioxidant properties of the extract and compounds were assessed by the measurement of the total phenolic content, ascorbic acid content, total antioxidant capacity and 1-1-diphenyl-2-picryl hydrazyl (DPPH) and hydrogen peroxide radicals scavenging activities.Compounds 3, 6, 7 and ethanolic extract had DPPH scavenging activities with IC50 values of 186, 75, 17 and 102 μg/ml respectively when compared to vitamin C with 15 μg/ml. On the other hand, no significant results were obtained for hydrogen peroxide radical. In addition, compound 7 has the highest phenolic content of 0.81±0.01 mg/ml of gallic acid equivalent while compound 8 showed the highest total antioxidant capacity with 254.31±3.54 and 199.82±2.78 μg/ml gallic and ascorbic acid equivalent respectively. Compound 4 and ethanolic extract showed a high ascorbic acid content of 2.26±0.01 and 6.78±0.03 mg/ml respectively.The results obtained showed the antioxidant activity of the ethanolic extract of C. bonduc and deduced that this activity was mediated by its isolated bioactive compounds