Sodium alginate is one of the most interesting and the most investigated and applied biopolymers due to its advantageous properties. Among them, easy, simple, mild, rapid, non-toxic gelation by divalent cations is the most important. In addition, it is abundant, low-cost, eco-friendly, bio-compatible, bio-adhesive, biodegradable, stable, etc. All those properties were systematically considered within this review. Carotenoids are functional components in the human diet with plenty of health benefits. However, their sensitivity to environmental and process stresses, chemical instability, easy oxidation, low water solubility, and bioavailability limit their food and pharmaceutical applications. Encapsulation may help in overcoming these limitations and within this review, the role of alginate-based encapsulation systems in improving the stability and bioavailability of carotenoids is explored. It may be concluded that all alginate-based systems increase carotenoid stability, but only those of micro- and nano-size, as well as emulsion-based, may improve their low bioaccessibility. In addition, the incorporation of other biopolymers may further improve encapsulation system properties. Furthermore, the main techniques for evaluating the encapsulation are briefly considered. This review critically and profoundly explains the role of alginates in improving the encapsulation process of carotenoids, suggesting the best alternatives for those systems. Moreover, it provides a comprehensive cover of recent advances in this field.

Three populations of Thymus pannonicus grown in Serbia (one from northern and two from east Serbia) were examined for chemical composition of their essential oil. Thymus pannonicus is used in traditional medicine and it is collected by local people in the studied regions, hence the interest in composition of its essential oils. Three major groups of essential oil components were identified, such as monoterpene hydrocarbons, oxygenated monoterpene hydrocarbons and sesquiterpene hydrocarbons. Each of investigated populations showed its own chemotype, including: geranial (citral), α-pinene and germacrene-D. To best of our knowledge, this sesquiterpene hydrocarbon was reported as a major component in Thymus bracteosus only. In these populations the phenolic compounds thymol and carvacrol, considered as most frequent constituents of essential oil in Thymus taxa, haven’t been found in significant quantities.

The aim of this research is to investigate the potential of Raman and FT-IR spectroscopy as well as mathematical linear and non-linear models as a tool for the discrimination of different seed varieties of paprika, tomato, and lettuce species. After visual inspection of spectra, pre-processing was applied in the following combinations: (1) smoothing + linear baseline correction + unit vector normalization; (2) smoothing + linear baseline correction + unit vector normalization + full multiplicative scatter correction; (3) smoothing + baseline correction + unit vector normalization + second-order derivative. Pre-processing was followed by Principal Component Analysis (PCA), and several classification methods were applied after that: the Support Vector Machines (SVM) algorithm, Partial Least Square Discriminant Analysis (PLS-DA), and Principal Component Analysis-Quadratic Discriminant Analysis (PCA-QDA). SVM showed the best classification power in both Raman (100.00, 99.37, and 92.71% for lettuce, paprika, and tomato varieties, respectively) and FT-IR spectroscopy (99.37, 92.50, and 97.50% for lettuce, paprika, and tomato varieties, respectively). Moreover, our novel approach of merging Raman and FT-IR spectra significantly contributed to the accuracy of some models, giving results of 100.00, 100.00, and 95.00% for lettuce, tomato, and paprika varieties, respectively. Our results indicate that Raman and FT-IR spectroscopy coupled with machine learning could be a promising tool for the rapid and rational evaluation and management of genetic resources in ex situ and in situ seed collections.

Thymus is one of the largest genera in the Lamiaceae family, and all its species are used as medicinal and aromatic plants. In this research, Raman spectroscopy is used as a fast and nondestructive tool for chemotype assessment by measuring spectra directly from glandular trichomes. Samples of two Thymus pulegioides subsp. pannonicus populations were collected from Banat (Serbia), analyzed using a 785 nm laser, and compared with reference spectra of citral and thymol standards. Spectra of samples from the Vršačke planine locality showed the presence of dominant bands related to citral (around 1671 and 1633 cm-1). Spectra of samples from the Devojački bunar locality displayed dominant bands at around 1640 and 1668 cm-1, corresponding to ν(C=C) and ν(C=O) vibrations related to conjugated and oxygenated monoterpene stretching, respectively. The dominant bands of thymol were at 740, 1062, and 1262 cm-1, confirming that samples from Devojački bunar are not of the thymol chemotype. GC-FID/MS analysis revealed that germacrene D is a major compound in the essential oil from this population. Additionally, PCA revealed a clear separation of the two investigated populations, demonstrating that Raman spectroscopy can be used for chemotype differentiation.

In this study, carotenoids from four different paprika genotypes were analyzed at various maturation stages, as well as in Ajvar, a traditional Balkan product made from fully matured roasted paprika fruits. For this purpose, the HPTLC analytical method was used, and five dominant carotenoids were analyzed: β-carotene, lutein, zeaxanthin, capsanthin, and β-cryptoxanthin. Additionally, total carotenoids were analyzed spectrophotometrically, antioxidant capacity was determined, and their bioavailability was assayed using in vitro digestion. Finally, Raman spectroscopy, a non-destructive analytical method, was used to estimate the total carotenoid content. The results showed that the amount of all investigated carotenoids is the highest in the final maturity stage (0.38 g/100 g DM to 1.55 g/100 g DM). On the other hand, the lowest concentration of all investigated carotenoids was detected at the first stage of maturation, ranging from 0.01 g/100 g DM to 0.25 g/100 g DM. However, the analysis of carotenoid content in Ajvar showed a tendency for a decrease in concentration compared to their quantity in fresh fruits, although this was also dependent on the genotype (1.9–66.98% according to HPTLC results and 16.14–82.36% according to spectrophotometry). Antioxidant tests indicated an increase in antioxidant capacity with the ripening of paprika fruits, confirming the role of carotenoids as compounds capable of neutralizing harmful oxygen species (DPPH ranged from 0.21 to 1.50 µmol/g TEAC, CUPRAC ranged from 0.185 to 0.297 mg AsA/g DM, FRP ranged from 9.33 to 25.66 mg AsA/g DM). Quantification of total carotenoids by Raman spectroscopy showed that results were highly correlated with those obtained by HPTLC and the spectrophotometric method, highlighting the potential of Raman spectroscopy for carotenoid quantification. Based on the obtained results, it can be concluded that the traditional product Ajvar represents an important source of carotenoids, which are preserved after heat treatment with high biological activity relative to the final ripening stage of the paprika. Furthermore, the bioavailability of carotenoids from Ajvar is significantly higher compared to the results from fresh paprika analysis.