Characterization of the Polyphenolic Profile in Tomato (Lycopersicon esculentum P. Mill) Peel and Seeds by LC-HRMS/MS.

Peel and seeds are the main byproducts from tomato (Lycopersicon esculentum P. Mill) processing with high concentrations of polyphenols that have been underexploited. Herein, polyphenolic profiles in tomato peel and seeds were elucidated by untargeted liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) with an LTQ Orbitrap analyzer. Samples from two Spanish regions─"Murcia" and "Almería"─were analyzed to obtain complementary results. 57 compounds were found, mainly phenolic acids and flavonoids, of which eight were identified for the first time in tomato. Polyphenols were more abundant in byproducts from "Murcia" samples than in those from"Almería" samples, where the abundance of compounds like coutaric, caffeic, neochlorogenic, dicaffeoylquinic and ferulic acids, vanillic acid hexoside, catechin, naringenin, prunin, apigenin-O-hexoside, rutin, and rutin-O-pentoside was even much higher in byproducts than that in whole fruits. These results reveal the wide range of polyphenols found in tomato byproducts, with potential applications in pharmaceutical research, food preservation, and cosmetic development, among others.

Fast FRAP-SIA method to determine antioxidant capacity.

One of the most used methods to measure antioxidant capacity in food is the ferric reducing antioxidant power (FRAP) test, which is simple, sensitive, and economical, nevertheless has long analysis times, causing measurement errors due to the instability of the FRAP reagent due to its precipitation sequential injection analysis (SIA) is a flow technique that can correct these disadvantages because it is more quickly. So, a novel FRAP-SIA method was developed to evaluate the antioxidant capacity. The system was optimized using a central composite design for hydrodynamic and chemical factors, resulting in a flow rate of 35 µL s-1, and aspirate volumes of 33 µL-38 µL-33 µL for the sequence (FRAP-Antioxidant-FRAP). FRAP reagent was prepared with an HCl solution at 0.005 mol L-1, improving its stability 24 times, concerning when it is in acetate buffer at pH 3.6. The method showed excellent accuracy (RSD <3%) with a LOD of 1.0 µmol L-1 of Trolox for a linear range of 5-120 µmol L-1. The reaction time was diminished by 96% concerning the FRAP-microplate assay (from 30 min to 1.2 min). The method was applied in beverages and extracts, obtaining recovery values ranging from 91.24 to 114.22%.

Effect of Microwave and Ultrasound during the Killing Stage of the Curing Process of Vanilla (Vanilla planifolia, Andrews) Pods.

The curing process (CP) of Vanilla planifolia pods, which is a long and tedious process, is necessary to obtain the natural vanilla extract. This research evaluated the application of microwave (M) and ultrasound (U) during the "killing" stage of the CP and its effect on vanillin content and ß-glucosidase activity. The pods were immersed in a container with water or with moistened samples for the M treatments. In U treatments, the pods were immersed in an ultrasonic bath. After this stage, the samples were subjected to an additional U treatment. The results show that the application of these technologies significantly improves vanillin yield (p < 0.05) and the curing time is reduced to 20 days. U treatments subjected to additional sonication at 38 °C obtain more than double the yield of vanillin regarding control. The effect of M and U on cell structure damage increases with additional sonication, but at 15 min, ß-glucosidase inactivation decreases the final yield. Disposition of samples in M also affects the final vanillin content. There is no significant correlation between ß-glucosidase and vanillin in the different treatments. The application of M and U with the appropriate parameters reduces the CP time without affecting the compounds of interest.

Exploring the potential of paper-based analytical sensors for tea geographical origin authentication.

Tea (Camellia sinensis (L.) Kuntze-surname of German origin) is a popular beverage consumed worldwide due to its health benefits. Its quality depends on measuring features that may discriminate teas from distinct provenances. Protected designation of origin (PDO) is therefore a very useful label for tea quality evaluation. In the present work, antioxidant activity profiles obtained from microfluidic paper-based analytical devices (µPADs) were analyzed by chemometrics to determine the tea geographic origin. Based on the existing literature, we constructed a database containing chemical data from 26 samples and evaluated it by principal component analysis (PCA) coupled to linear discriminant analysis (LDA). Antioxidant activity was an effective LDA predictor for sample discrimination accomplishing accuracies from 75 to 82%. Modeling performance was favored by an external validation method. The best classification model was found using the first nine PCs as input variables. Training samples achieved a perfect success rate, while the test ones were predicted with 83% specificity, 100% sensitivity, and 90% overall accuracy. The modeling robustness was verified by integrating AUC (0.943) from ROC curve. The PCA-LDA approach taken here demonstrated that the teas coming from different countries can be correctly authenticated through µPADs, thus contributing to certificate samples PDO. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05440-1.

Fast ORAC-SIA method for antioxidant capacity determination in food samples.

A novel fluorescent ORAC-SIA method to determine antioxidant capacity in several food samples using fluorescein as the probe was developed. The optimization of the method was through a multivariable design, decreasing the analysis time to 5 min and the AAPH concentration to 67% compared with 90 min in the standard 96-well microplate method. The aspiration order was AAPH-sample/standard-fluorescein injected into a stream of a water-based carrier. The calculation of the antioxidant capacity was done from the fluoresceine peak heigh, so neither delay time nor area measurement was necessary. The proposed method showed excellent precision (RDS < 3%) with a LOD of 3.13 µmol L-1 and recoveries from 90% to 107%. The results from the ORAC-SIA method did not show a significant difference from the microplate method.

Microdevice based on centrifugal effect and bifurcation law for separation of plasma from on-line diluted whole blood.

In recent decades, scientific interest in the development of devices capable of performing routine clinical analyses through the application of standardized traditional laboratory protocols in a miniaturized lab-on-a-chip device has increased. In the present work, an innovative microdevice for the on-line whole blood dilution with a phosphate buffer solution (PBS) and separation of plasma was designed, manufactured, and characterized. The microdevice was constructed with a rectangular cross-section and spiral-shaped microchannels by photolithography and soft litography. Also, the widths of the diluted plasma and the remaining blood outlet microchannels were different to create a difference in the outlet flow rates to facilitate and achieve the plasma separation based on the combination of centrifugal effect (Dean drag force) and bifurcation law (Zweifach-Fung effect). The separation purity (α) under the separation conditions (total flow rates between 25 and 100 µL/min, entrance flow rate ratio PBS/whole blood between 4 and 10, and hematocrit (% HCT) between 3 and 8) was around 100% for fresh blood samples, while the separation efficiency (ß) was between 8 and 13%. The concentration in the separated diluted plasma was between 0.1 and 0.7% (v/v) with plasma flow rates between 3 and 7 µL/min, respectively. The quality of the diluted and separated plasma from micordevice was corroborated from a blood sample from a patient diagnosed with rheumatoid arthritis through the quantification of anti-cyclic citrullinated peptide (anti-CCP) antibodies employing a microdevice immunoassay. The developed microdevice has a high potential to be coupled with the on-line detection of biomarkers.

Integrated On-Chip 3D Vascular Network Culture under Hypoxia.

We developed a portable device made of poly(dimethylsiloxane) (PDMS)/polymethylmethacrylate (PMMA) for long-term 3D cell culture of vascular endothelial cells for the development of a vascular network and evaluated the device under different transitions between normoxia and hypoxia with good optical accessibility. The combination of a nested reservoir device and a bicarbonate/ascorbate buffer system accomplished on-chip incubation with 4.91 ± 0.86% pO2 and 5.19 ± 1.70% pCO2 for up to 10 days. Seventy-two hours of normoxic incubation preceding hypoxic culture increased the cell viability, network formation, and size and stability of the resulting lumens compared with those completely maintained in normoxia for the same total duration. We employed different parameters of the network (e.g., total mesh area, total length, number of branches, among others) for the comparison of different oxygen treatments in the device. The differential effect of hypoxic conditions based on the maturity of the vessels may be used as an external factor to improve vascular development in vitro.