Fermented juices as reducing and capping agents for the biosynthesis of size-defined spherical gold nanoparticles

Gold nanoparticles (AuNPs) are of scientific and industrial significance; however, the traditional synthesis methods employ toxic compounds. Hence, non-toxic and environmentally friendly AuNPs synthesis methods are of special interest. Here, AuNPs were produced using four solutions of fermented grape juices. UV/Vis absorption spectrophotometry and transmission electron microscopy indicated that AuNPs synthesized with a solution based on semi-sweet red grapes were mostly spherical with narrow size distribution (average diameter of 82.1 ± 36.2 nm). AuNPs of similar spherical morphology but smaller size were obtained using a solution based on semi-dry red grapes (57.1 ± 16.4 nm). A large variety of AuNPs shapes and broader size distribution were produced when solutions based on semi-sweet or dry white grapes were applied. In this case, the average sizes of the AuNPs were 271.6 ± 130.2 nm and 76.0 ± 47.2 nm, respectively. Using energy dispersive X-ray spectroscopy, Au, C, and O were detected, confirming formation of biogenic AuNPs in all cases. Mie theory calculations for AuNPs synthesized with the aid of solutions based on red grapes suggest that their optical properties are different and best suited for distinct downstream applications. Attenuated total reflectance Fourier transform infrared spectroscopy, the Folin-Ciocalteu assay, and the Bertrand's method were used to examine bioactive compounds present in the solutions applied for synthesis. Phenolics, and to a lesser extent reducing sugars, were identified as likely playing a significant role in reduction and stabilization of the AuNPs. These results display the great potential of these solutions for green synthesis of size defined AuNPs, and illustrate that different grape varieties may be used to obtain AuNPs with unique properties. Keywords: Nanostructures, Bioreduction process, Phenolics, Reducing sugars, Mie scatterin

Espectroscopia de infravermelho com transformada de Fourier na monitorização da produção de vinho

ReviewThe complexity of the wine matrix makes monitoring of the winemaking process from the grapes to the final product crucial for the wine industry. In this context, analytical methodologies that can combine good accuracy, robustness, high sample throughput, “green character”, and by preference real-time analysis, are on-demand to create high-quality vitivinicultural products. In the last years, Fourier-transform Infrared Spectroscopy (FTIR) combined with chemometric analysis has been evaluated in several studies as an effective analytical tool for the wine sector. Some applications of FTIR spectroscopy have been already accepted by the wine industry, mainly for the prediction of basic oenological parameters, using portable and non-portable instruments, but still many others are waiting to be thoroughly developed. This literature review aims to provide a critical synopsis of the most important studies assessing grape and wine quality and authenticity, and to identify possible gaps for further research, meeting the needs of the modern wine industry and the expectations of most demanding consumers. The FTIR studies were grouped according to the main sampling material used - 1) leaves, stems, and berries; 2) grape must and wine applications - along with a summary of the basic limitations and future perspectives of this analytical techniqueA complexidade da matriz do vinho torna a monitorização da sua produção, desde a maturação da uva até o produto final, fundamental para a indústria do vinho. Neste contexto, metodologias analíticas com boa exactidão, robustez, elevado rendimento de amostras, menos penalizadoras para o meio ambiente, e se possível capazes de fornecer resultados em tempo real, são muito importantes para a obtenção de produtos vitivinícolas de alta qualidade. Nos últimos anos, a Espectroscopia de Infravermelho com Transformada de Fourier (FTIR) combinada com a análise quimiométrica tem sido avaliada em diversos estudos por ser uma ferramenta analítica apropriada para o setor vitivinícola. Algumas aplicações de FTIR já foram adoptadas pela indústria do vinho, principalmente para a predição de parâmetros enológicos básicos, através de instrumentos portáteis e não portáteis, mas há ainda um enorme potencial de desenvolvimento a explorar. A presente revisão da literatura tem como objetivo fornecer uma sinopse crítica dos estudos mais importantes realizados para avaliação da qualidade e autenticidade do vinho e identificar possíveis lacunas para investigação futura, indo ao encontro das necessidades da indústria vinícola moderna e das expectativas dos consumidores mais exigentes. Os estudos sobre FTIR foram agrupados de acordo com o principal material de amostragem - 1) folhas, engaços e bagos; 2) mostos e vinhos - juntamente com informação sobre as limitações básicas e perspectivas futuras desta técnica analíticainfo:eu-repo/semantics/publishedVersio

SILVER MIRROR SUBSTRATE AND ROLLING METHOD FOR IMPROVED SURFACE-ENHANCED RAMAN SPESCTROSCOPIC ANALYSIS IN FOOD

Surface-enhanced Raman spectroscopy, short for SERS, is an emerging technology with great potential in food analysis due to rapid detection, high sensitivity, portable instrumentation, and simple sample preparation. However, it is always a bottleneck to obtain reproducible SERS measurements in real analytical cases due to the complicity of food systems and inhomogeneous aggregation of colloidal nanoparticles. To improve its performance for practical applications in food analysis, efforts have been made in improving the reproducibility, enhancing the selectivity and reducing the matrix interference to the analyte. Herein, a self-assembly silver nanoparticles mirror substrate was fabricated to improve the and the quantitative ability and effectiveness of sample preparation for different applications in food analysis, including pesticides detection in beverages, chemical profiling of red wines, and headspace analysis of garlic. The AgNPs mirror was fabricated using the interface between polar and non-polar solvents and showed a uniform arrangement of nanoparticles under the microscope. It demonstrated a great reliability for the detection of a pesticide fonofos in beverages (i.e., apple juice and green tea). AgNPs mirror can also be in situ fabricated in red wines to generate a comprehensive spectrum constituted by signals of five wine phytochemicals, which provided a great potential of SERS in the differentiation, authentication, and quality/safety control of red wines. AgNPs mirror also showed great potential in the headspace characterization of aromatic compounds from Allium species plants. Additionally, a facile rolling method was developed to enrich analyte (i.e., chlordane pesticide) and to amplify its weak SERS activity and a mathematic model was generated and successfully quantified the chlordane in a complicated crude oil sample with a very good recovery. Overall, AgNPs mirror and the rolling method overcame the reproducibility and sensitivity problems for SERS in several challenging food matrices. With these improvements, SERS can be much more reliable for analytical applications and its range of targets can be widely expanded

A Narrative Review of Recent Advances in Rapid Assessment of Anthocyanins in Agricultural and Food Products

Anthocyanins (ACNs) are plant polyphenols that have received increased attention recently mainly due to their potential health benefits and applications as functional food ingredients. This has also created an interest in the development and validation of several non-destructive techniques of ACN assessments in several food samples. Non-destructive and conventional techniques play an important role in the assessment of ACNs in agricultural and food products. Although conventional methods appear to be more accurate and specific in their analysis, they are also associated with higher costs, the destruction of samples, time-consuming, and require specialized laboratory equipment. In this review article, we present the latest findings relating to the use of several spectroscopic techniques (fluorescence, Raman, Nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, and near-infrared spectroscopy), hyperspectral imaging, chemometric-based machine learning, and artificial intelligence applications for assessing the ACN content in agricultural and food products. Furthermore, we also propose technical and future advancements of the established techniques with the need for further developments and technique amalgamations

Aplicación de técnicas espectroscópicas vibracionales al estudio de la extractabilidad de compuestos fenólicos procedentes de subproductos enológicos.

Las características de la uva en el momento de la vendimia condicionan en gran medida la calidad del vino elaborado a partir de ellas. En regiones de clima cálido, las altas temperaturas ambientales, acentuadas en las últimas décadas por los efectos del cambio climático, originan un desfase entre la madurez tecnológica de la uva, cada vez más temprana y la madurez fenólica, cada vez más tardía, que desencadena, entre otros, problemas de estabilidad cromática en el envejecimiento. Ante esta situación se pone de manifiesto la necesidad de implementar medidas de adaptación que permitan preservar la calidad de estos vinos. En este sentido, el aprovechamiento de subproductos de la industria vitivinícola ricos en compuestos fenólicos,como pueden ser las virutas de madera cruda de las tonelerías,añadidas en etapas iniciales de la vinificación, se presenta como una estrategia enológica, nueva y sostenible, para paliar los efectos del cambio climático en la calidad de los vinos tintos.Los compuestos fenólicos de la madera, que pasarán al vino durante el proceso de maceración, junto con los compuestos fenólicos procedentes de la uva, determinarán la composición fenólica del vino y condicionarán sus características cromáticas y organolépticas. Tradicionalmente,la composición fenólica, y la facilidad de cesión de estos compuestos al vino desde diferentes matrices, se ha controlado por métodos de análisis fisicoquímicos que,en muchos casos, resultan complejos y tediosos. En las últimas décadas se han desarrollado técnicas espectroscópicas que permiten estimar de forma rápida, no destructiva y respetuosa con el medio ambiente,distintos parámetros de interés enológico. En este trabajo, inicialmente se ha evaluado el efecto que tiene la adición de chips de madera en la extracción de compuestos antociánicos del hollejo de uva tinta clasificada hiperespectralmente como uva con baja capacidadde cesión de dichos compuestos.Se ha comprobadoque la adición de copigmentos provenientes de la madera, que contribuyen a mejorar el color del vino,noalterael equilibrio de extracción de antocianos del hollejo. Se ha utilizado el análisis de imagen hiperespectral en la región del infrarrojo cercano y la regresión por mínimos cuadrados parciales (MPLS)para analizar de forma rápida el contenido total yel contenido extraíble de fenoles totales y flavanoles en semillas de uva tinta.De forma similar, se ha desarrollado un modelo MPLS para predecir el contenido fenólico extraíble en viruta cruda de roble. Se ha evaluado la capacidad dela espectroscopía NIR portátilpara estimar in situ de forma rápida el contenido fenólico extraíble delhollejo de uva y de la viruta cruda de roble. La influencia de las condiciones ambientalesen el viñedo en el momento de la adquisición espectral pueden condicionar los resultados obtenidos para los hollejos, de forma que los modelos presentan errores que comprometen su aplicación con fines predictivos. Sin embargo, en virutas de roble, los modelos propuestos para lapredicción del contenido extraíble de fenoles totales y de elagitaninosofrecen resultados satisfactorios para todos los parámetros evaluados. Así mismo, utilizando espectroscopía en el infrarrojo medio por transformada de Fourier y espectroscopíaRaman se han caracterizado muestrasde viruta cruda de madera y se han relacionado las características espectrales con la facilidad de extracción de compuestos fenólicos. De esta forma, se ha podido confirmar la relación existente entre la extractabilidad de compuestos fenólicos en viruta de madera y la composición y distribución de los componentes de su pared celular.La microscopía electrónica de barrido (SEM) aporta información topográfica complementaria que respalda la relación entre la estructura de la madera y los niveles de extractabilidad fenólica. Por último, se ha evaluado objetivamente el potencial enológico de la viruta cruda de roble, subproducto de tonelería. Para ello se ha determinado,en una situación real de vinificación en tinto, la influencia de la adición post-fermentativade virutas en la composición fenólica y la calidad cromática de vinos tintos de variedad Syrah.Los resultados obtenidos demuestran que la adición pos-fermentativa de viruta de madera cruda representa un procedimiento útil para la elaboración de vinos tintos en clima cálido, ya que produce una mejora tanto de la composición fenólica como de la calidad y estabilidad cromática.Premio Extraordinario de Doctorado U

Extraction Systems and Analytical Techniques for Food Phenolic Compounds: A Review

Phenolic compounds are highly valuable food components due to their potential utilisation as natural bioactive and antioxidant molecules for the food, cosmetic, chemical, and pharmaceutical industries. For this purpose, the development and optimisation of efficient extraction methods is crucial to obtain phenolic-rich extracts and, for some applications, free of interfering compounds. It should be accompanied with robust analytical tools that enable the standardisation of phenolic-rich extracts for industrial applications. New methodologies based on both novel extraction and/or analysis are also implemented to characterise and elucidate novel chemical structures and to face safety, pharmacology, and toxicity issues related to phenolic compounds at the molecular level. Moreover, in combination with multivariate analysis, the extraction and analysis of phenolic compounds offer tools for plant chemotyping, food traceability and marker selection in omics studies. Therefore, this study reviews extraction techniques applied to recover phenolic compounds from foods and agri-food by-products, including liquid–liquid extraction, solid–liquid extraction assisted by intensification technologies, solid-phase extraction, and combined methods. It also provides an overview of the characterisation techniques, including UV–Vis, infra-red, nuclear magnetic resonance, mass spectrometry and others used in minor applications such as Raman spectroscopy and ion mobility spectrometry, coupled or not to chromatography. Overall, a wide range of methodologies are now available, which can be applied individually and combined to provide complementary results in the roadmap around the study of phenolic compounds

Study of phenolic content and antioxidant activity of Greek red and white wines by means of classical methods and FTIR

Phenolic and antioxidant contents of wines are very important in terms of both flavour attributes and health benefits. Changes occur during ageing of wine in containers (e.g. wooden barrels) in relation to their antioxidant activity and phenolic content. Vilana, Dafni, Kotsifali and Mandilari single variety Cretan wines, were vinificated to determine their antioxidant activity and phenolic content Wines were aged in different containers after two vinifications. Changes in the above characteristics were determined every three months for a twelve month period. Stainless steel with and without oenosticks containers, American oak, French oak, Acacia and Chestnut barrels were used for wine ageing. As far as phenolic and antioxidant contents are concerned, ageing of wine in chestnut barrels, Kotsifali and Mandilari (red wines) and in Acacia barrels for Vilana and Dafni (white wines), gave the best results, achieving the highest phenolic content and antioxidant activity after 12 months of ageing. The phenolic fingerprints of Vilana, Dafni, Kotsifali and Mandilari wines were determined for the first time. The phenolic fingerprint of wines has been recently used for the authentication and discrimination of red wines. In this study, attempt has also been made to use the phenolic fingerprint of white wines, for authentication. Differences were observed in Kotsifali and Mandilari (red wines) and in Vilana and Dafni (white wines) directly after vinification, allowing their discrimination. Also the changes in their phenolic fingerprints were monitored during ageing in different containers for a 12 month period. The effect of hydroxytyrosol and oleuropein on wine spoilage induced by acetic acid bacteria was also determined. Hydroxytyrosol was better than oleuropein in controlling the increase of volatile acidity, causing wine spoilage. Wines treated with 0.5mg/l hydroxytyrosol showed control of volatile acid production, and may be a promising alternative to sulphites in wine production in the future. Finally, extracts obtained from olive oil mills and winery by-products were used in Vilana vinification instead of sulphites and antioxidant activity and phenolic content of the wines determined

Development of innovative antioxidant food packaging systems based on natural extracts from food industry waste and Moringa oleifera leaves

Active packaging that prolongs food shelf life, maintaining its quality and safety, is an increasing industrial demand, especially if integrated in a circular economy model. In this study, the fabrication and characterization of sustainable cellulose-based active packaging using food-industry waste and natural extracts as antioxidant agents was assessed. Grape marc, olive pomace and moringa leaf extracts obtained by supercritical fluid, antisolvent and maceration extraction in different solvents were compared for their antioxidant power and phenolic content. Grape and moringa macerates in acetone and methanol, as the most efficient and cost-effective extracts, were incorporated in the packaging as coatings or in-between layers. Both systems showed significant free-radical protection in vitro (antioxidant power 50%) and more than 50% prevention of ground beef lipid peroxidation over 16 days by indirect TBARS and direct in situ Raman microspectroscopy measurements. Therefore, these systems are promising for industrial applications and more sustainable farm-to-fork food production systems