Convergent technologies to tackle challenges of modern food authentication

The authentication process involves all the supply chain stakeholders, and it is also adopted to verify food quality and safety. Food authentication tools are an essential part of traceability systems as they provide information on the credibility of origin, species/variety identity, geographical provenance, production entity. Moreover, these systems are useful to evaluate the effect of transformation processes, conservation strategies and the reliability of packaging and distribution flows on food quality and safety. In this manuscript, we identified the innovative characteristics of food authentication systems to respond to market challenges, such as the simplification, the high sensitivity, and the non-destructive ability during authentication procedures. We also discussed the potential of the current identification systems based on molecular markers (chemical, biochemical, genetic) and the effectiveness of new technologies with reference to the miniaturized systems offered by nanotechnologies, and computer vision systems linked to artificial intelligence processes. This overview emphasizes the importance of convergent technologies in food authentication, to support molecular markers with the technological innovation offered by emerging technologies derived from biotechnologies and informatics. The potential of these strategies was evaluated on real examples of high-value food products. Technological innovation can therefore strengthen the system of molecular markers to meet the current market needs; however, food production processes are in profound evolution. The food 3D-printing and the introduction of new raw materials open new challenges for food authentication and this will require both an update of the current regulatory framework, as well as the development and adoption of new analytical systems.

Resonant Raman Spectroscopy of Carotenoids in Aging of Extra Virgin Olive Oil

This work uses resonant Raman spectroscopy (RRS) to investigate changes in carotenoid concentration in extra virgin olive oil (EVOO) as it oxidizes under accelerated thermal aging. Carotenoids are nutritious antioxidants and biomarkers that represent the general quality of olive oil. HPLC is the conventional method used to determine the concentration of carotenoids, but it is expensive, time-consuming, and requires sample handling. A simple optical technique for estimating carotenoid concentration in extra virgin olive oil is, therefore, desirable. This work shows that the normally weak carotenoid signal is strongly amplified when using the resonant Raman technique. The aging and oxidation of EVOO decreases the Raman intensities associated with carotenoids and increases the fluorescence and Raman intensities associated with fatty acids. From these quantities, two Raman intensity ratios are presented as indicators of the effects of aging.

Ultrasensitive detection of pectin based on the decarboxylation reaction and surface-enhanced Raman spectroscopy

In the present study, a novel simple and sensitive method was developed for the determination of pectin based on the decarboxylation derivatization reaction and surface-enhanced Raman scattering (SERS) without complicated separation steps. The derivatization reaction can be controlled by the experimental parameters such as reaction time, temperature and the amount of hydrochloric acid. Additionally, the method was used to accurately and reliably detect pectin added in honey or apple, which can be detected at levels as low as 0.5 or 0.01 ppm, respectively. Based on the conventional decarboxylation reaction, a simple and sensitive SERS method was proposed for the detection of pectin, which shows potential for practical application.

One drop only. Easy and rapid Raman evaluation of β-carotene in olive oil and its relevance as an index of olive fly attack

This paper presents, for the first time, a method for the rapid quantification of β-carotene in olive oil by Raman spectroscopy. Using a 532 nm Raman laser source, our procedure requires only one drop (100 µL) of oil, for β-carotene content to be determined. Results show that β-carotene content is associated with the lutein/β-carotene ratio, a parameter whose value describes how healthy the olives were before processing, specifically whether an olive fly attack occurred. Since olive fly attacks are not always visible to the oil producers, this method gives them the means to control the validity of the prevention strategies they adopted.

Microstructure and molecular vibration of mannosylerythritol lipids from Pseudozyma yeast strains

This work highlights microstructure and molecular vibration of mannosylerythritol lipids (MELs) from Pseudozyma aphidis B1 and Pseudozyma hubeiensis TS18 strains collected from brown algae and mangrove sediments. The scanning electron microscopy (SEM) shows the elongated structures with polar budding in the cells of B1 and TS18 yeast strains. The high-resolution transmission electron microscopy (HRTEM) identifies large lipid bodies that contain MELs confirmed by the anthrone test and thin layer chromatography. The HRTEM also reveals unknown electron dense inclusions. The surface-enhanced Raman scattering (SERS) was used to analysis molecular vibrations of cells, MEL mixtures, and purified MELs (A, B, and C) extracted from the B1 and TS18 cells. The peak analysis of Raman spectra suggests a higher level of saturation per fatty acid chain in MEL-B in both B1 and TS18 cells. This work demonstrates that the out-of-plane bending vibrations of the CH bonds in the range of 840-940 cm^-1 can serve an efficient indicator for detecting MEL-A, -B, and -C.

ECO-FRIENDLY hybrid hydrogels for detection of phenolic RESIDUES in water using SERS

Herein is presented a simple and sensible method to determine organic pollutants in water, based on the utilization of silver nanoparticles (AgNPs) loaded in Polyacrylamide (PAAm)/starch hybrid hydrogels combined with surface-enhanced Raman scattering (SERS) spectroscopy. The materials were characterized by swelling degree studies, UV-Visible spectroscopy (UV-Vis), X-ray diffraction (XRD) and scanning electron microscopy (SEM). PAAm/starch hydrogels showed variable swelling capacity, according to the synthetic molar composition. The most promising results were attributed to lower concentrations of starch and crosslink agent (N,N'-methylenebisacrylamide - MBA). Spectroscopic analysis confirmed the formation of AgNPs, by noticing the peak at around 420 nm, due to its surface plasmon resonance (SPR) effect. The results showed that AgNPs were stabilized by hydrogels networks. The average size of the AgNPs was smaller than 100 nm and the size and quantity of nanoparticles were influenced by the molar composition of the hydrogel matrix. The SERS substrate based on the AgNPs-PAAm/starch exhibited reproducibility, stability, and limit of detection (LOD) of phenol in water of 1 × 10^-8 M. The average mass of AgNPs-PAAm/starch hydrogels used for each detection analysis was around 10 mg. The spectra with enhanced intensities were possible due to a large number of hot spots generated on the AgNPs-PAAm/starch hydrogel substrate, which leads to potential use for organic pollutant detection. In addition, there is also the possibility of reusing the hydrogel matrix substrate in other analyzes.