Raman spectroscopy of chocolate bloom
Raman spectroscopy has been widely applied to the chemical analysis of food quality and, in particular, of chocolate. We perform Raman analysis of bloom formation in white and dark chocolates. We show evidence of sugar and fat bloom and investigate spectroscopic signatures of polymorphic changes in different phases.
Applications of Microprobe Raman Spectroscopy in Food Science
The Raman microprobe combines the analytical properties of Raman spectroscopy and the visualization capabilities of a high quality microscope, allowing localization and identification of species and phases in time intervals of seconds to a few minutes with a spatial resolution down to 1 µm. This article describes the basic principles of operation of the Raman microprobe and some applications that are important in food technology: in situ differentiation between sucrose and lactose crystals and of amorphous and crystalline phases in sucrose; detection of semi-crystalline and gelatinized zones in starch granules, and phase transitions in cocoa butter after heating (melting)/cooling (crystallization) cycles. Extensions of these applications cover the entire range of food constituents. La microprobeta Raman combina las propiedades analíticas de la espectroscopía Raman y la capacidad de visualizar áreas de un buen microscopio óptico, que permiten la localización e identificación de compuestos y fases en un material. La resolución alcanza hasta 1 µm y los ensayos se realizan en tiempos de segundos a unos pocos minutos, con una preparación mínima de la muestra. Este artículo describe los principios básicos de la operación de la microprobeta Raman y algunas aplicaciones importantes en tecnología de alimentos: diferenciación directa entre cristales de sacarosa y lactosa y entre las fases amorfa y cristalina de sacarosa; caracterización de gránulos de almidón semi-cristalinos y gelatinizados, y transiciones de fase en manteca de cacao después de un ciclo de calentamiento (fusión)/enfriamiento (cristalización). Estas aplicaciones pueden hacerse extensibles a casi todo el espectro de los componentes de alimentos.
Detecting Food‐ and Waterborne Viruses by Surface‐Enhanced Raman Spectroscopy
Abstract:  Food‐ and waterborne viruses pose serious health risks to humans and were associated with many outbreaks worldwide. Rapid, accurate, and nondestructive methods for detection of viruses are of great importance to protect public health. In this study, surface‐enhanced Raman spectroscopy (SERS) coupled with gold SERS‐active substrates was used to detect and discriminate 7 food‐ and waterborne viruses, including norovirus, adenovirus, parvovirus, rotavirus, coronavirus, paramyxovirus, and herpersvirus. Virus samples were purified and dialyzed in phosphate buffered saline (8 to 9 log PFU/mL) and then further diluted in deionized water for SERS measurement. After capturing the characteristic SERS spectral patterns, multivariate statistical analyses, including soft independent modeling of class analogy (SIMCA) and principal component analysis (PCA), were employed to analyze SERS spectral data for characterization and identification of viruses. The results show that SIMCA was able to differentiate viruses with and without envelope with >95% of classification accuracy, while PCA presented clear spectral data segregations between different virus strains. The virus detection limit by SERS using gold substrates reached a titer of 102. Practical Application:  SERS is a simple, rapid, and accurate method for detection of food‐ and waterborne viruses. Our results demonstrate that coupled with gold substrates, SERS was able to rapidly detect and discriminate among different food‐ and waterborne viruses, indicating that SERS can provide rapid, sensitive, and reproducible detection results with minimum sample preparation for virus detection.