Green Solvents for Extraction of Natural Food Colorants from Plants: Selectivity and Stability Issues

Consumers associate the color of food with its freshness and quality. More and more attention is being paid to natural colorants that bring additional health benefits to humans. Such natural substances are the carotenoids (yellow to orange), the anthocyanins (red to blue), and the betalains (red and yellow), which are very sensitive to exposure to light, air, high temperatures, and chemicals. Stability and diversity in terms of color can be optimized by using environmentally friendly and selective extraction processes that provide a balance between efficacy, safety, and stability of the resulting extracts. Green solvents like water, supercritical fluids, natural deep eutectic solvents, and ionic liquids are the most proper green solvents when combined with different extraction techniques like maceration, supercritical extraction, and ultrasound-assisted or microwave-assisted extraction. The choice of the right extracting agent is crucial for the selectivity of the extraction method and the stability of the prepared colorant. The present work reviews the green solvents used for the extraction of natural food colorants from plants and focuses on the issues related to the selectivity and stability of the products extracted.

Menadione Contribution to the In Vitro Radical Scavenging Potential of Phytochemicals Naringenin and Lignin

Vitamin K3 (menadione), classified as a pro-vitamin, is a synthetic form of the fat-soluble family of vitamin K compounds. The combination of the vitamin with other molecules sharing structural and/or functional similarities, such as naturally occurring polyphenols, vitamins, or biopolymers, could potentiate mutual improvement of their antioxidant activity. The aim of the present study was to evaluate the role and contribution of vitamin K3 to the in vitro radical scavenging capacity of double and triple combinations with the phytochemicals naringenin and lignin, as well as assess possible intermolecular interactions between the bioactive compounds. Comparative analyses of the DPPH and ABTS radical scavenging activity of the pure substances vitamin K3, naringenin, and lignin; the two-component systems lignin/vitamin K3 and vitamin K3/naringenin; and the triple combination vitamin K3/flavonoid/lignin were carried out. The experimental results demonstrated increased DPPH and ABTS activities of the vitamin in combination with lignin compared to those of the two pure substances, i.e., a synergistic effect was observed. The registered significant increases in the radical scavenging activity of the triple combination determined via both methods are indicative of a remarkable potentiation effect, i.e., higher antioxidant potential exceeding the additive activity of the three pure substances.

Antimicrobial and Antioxidant Potential of Methanolic Extracts from Different Parts of Stevia rebaudiana Bertoni Cultivated in Bulgaria

Stevia rebaudiana Bertoni is a plant species which is frequently used not only as a sweetener, but also for its antibacterial and antioxidant properties. Nowadays, there are a large number of studies on the antimicrobial and antioxidant activity of S. rebaudiana leaves, but there are almost no data about the antimicrobial and antioxidant potential of extracts from the other parts of S. rebaudiana. The aim of the present study is to provide data of the antibacterial and antioxidant potential of methanolic extracts from different parts of S. rebaudiana (flowers, leaves, stems, rhizomes, and tubers) cultivated in Bulgaria. Antibacterial activity of the extracts against Staphylococcus aureus, Bacillus cereus and Escherichia coli was evaluated by agar well diffusion method, rutin content - by HPLC method, total phenolic content and radical scavenging potential - by UV-Vis analysis. S. rebaudiana extracts demonstrated antibacterial activity mainly against S. aureus - flower extracts expressed the highest activity, followed by the leaf and stem extracts. Only flower and leaf extracts demonstrated very low antibacterial activity against B. cereus. S. rebaudiana extracts did not show any antibacterial activity against E. coli. Methanolic extracts of this plant are rich in antioxidants. The highest concentrations of rutin and total phenols were found in the rhizomes of the plants, followed by the leaves, tubers, flowers, and stems, which corresponded to the radical scavenging potential of the same plant part. Comparisons between Trolox equivalents and gallic acid equivalents in different parts of S. rebaudiana on one hand, and Trolox equivalents and rutin concentration on the other hand showed a positive dependence and high values of the Pearson correlation - 0.9612 and 0.9707, respectively. The most important part of S. rebaudiana with medicinal significance (the leaves) has both comparatively good antibacterial activity and high antioxidant content, although the flowers and rhizomes expressed higher antibacterial and antioxidant activity, respectively. The experimental results imply that the cultivation area and climatic conditions of Bulgaria are very suitable for cultivation of S. rebaudiana plants with high content of antioxidants.

Cloacal bursa morphology in turkey broilers challenged with aflatoxin B1 alone or co-administered with Mycotox NG

Aflatoxins are toxic metabolites of moulds from the genus Aspergillus (Aspergillus flavus and Aspergillus parasiticus being the main producers). The aim of the present investigation was to evaluate the toxic effects of aflatoxin B1 on bursa of Fabricius morphology. Also, the possibility for prevention of toxic effects of AFB1 by feed supplementation of a mycosorbent (Mycotox NB) was studied. Experiments were carried out with sixty 7-day-old female turkey broilers (meat TM strain) divided into one control and five treatment groups (n=10). Groups were as followed: Group I – control (fed standard feed according to the species and age of birds); Group II – experimental, whose feed was supplemented with 0.5 g/kg Mycotox NG, Group III– experimental, whose feed contained 0.2 mg/kg aflatoxin B1, Group IV – experimental, whose feed contained 0.4 mg/kg aflatoxin B1, Group V – experimental, supplemented with 0.2 mg/kg aflatoxin B1 and 0.5 g/kg Mycotox NG and Group VI – experimental, supplemented with 0.4 mg/kg aflatoxin B1 and 0.5 g/kg Mycotox NG. The duration of the experiments was 42 days. The changes in bursal morphology in control and treated groups were followed out after the end of the study. In birds from experimental groups ІІI and IV, atrophy and degenerative changes have occurred in the bursa of Fabricius: reduction of lymphoid cell - populations in lymphoid follicles along with dystrophy. Feed supplementation with the tested toxin binder (Groups V and VI) resulted in partial neutralisation of deleterious effects of AFB1 on severity of histological lesions: interfollicular oedema, considerably lower lymphoid follicle rarefaction.

Effect of aflatoxin B1 alone or co-administered with Mycotox NG on the renal function and morphology of turkey broilers

The changes in relative weight of kidneys, blood plasma uric acid, urea, creatinine, calcium and inorganic phosphate, and the morphology of kidneys were investigated in turkey broilers with experimentally induced aflatoxicosis B1 (AFB1) treated or not with a mycosorbent (Mycotox NB). Experiments were carried out with 60 7-day-old female turkey broilers (meat TM strain) divided into one control and five treatment groups (n=10): Group I – control (0 mg/kg AFB1 not supplemented with Mycotox NG); Group II (0.5 g/kg Mycotox NG), Group III (0.2 mg/kg AFB1), Group IV (0.4 mg/kg AFB1), Group V (0.2 mg/kg AFB1 and 0.5 g/kg Mycotox NG) and Group VI (0.4 mg/kg AFB1 and 0.5 g/kg Mycotox NG). The changes in blood parameters were assayed on day 21 and 42. Blood analysis in groups III and IV on day 21 showed increased urea and creatinine concentrations and reduction in blood uric acid, calcium and inorganic phosphate. These changes tended to become more pronounced on day 42. The relative weight of kidneys was increased in groups III and IV after the end of the experiment. Morphological alterations of renal parenchyma in Groups I and II were not present. In birds from group III, desquamation of epithelial cells from the basement membrane, dilated glomerular subcapsular space and round-cell proliferation were noted. In Group V, these changes were far more severe and comprised granular and fatty dystrophy, karyolysis and plasmolysis, necrobiotic to necrotic processes, haemorrhages, congestion. The supplementation of the feed of groups V and VI with the tested toxin binder reduced the severity of reduction of kidneys’ relative weight, magnitude of changes in blood parameters, and the frequency and severity of histological lesions.

Experimental coccidiosis provoked by Eimeria acervulina in chicks simultaneously fed on ochratoxin A contaminated diet

The progression of coccidiosis provoked by Eimeria acervulina was followed in chicks fed on OTA-contaminated as well as on OTA-free diets. More heavy progress of duodenal coccidiosis, including mortality, occurred in OTA-treated chicks as can be seen from the higher value of lesion (3.50) and oocyst (31.65) indices. A stronger decrease of serum total protein was found in OTA-treated chicks (22.80 g/l) than in chicks infected with E. acervulina(24.20 g/l), but that decrease was strongest in chicks treated with OTA and simultaneously infected with E. acervulina (19.71 g/l). The serum concentration of uric acid was significantly increased in all chicks exposed to OTA, most notably in those additionally infected with E. acervulina (1020.6 (micro mol/L), whereas the serum enzyme activity of AST was increased only in chicks infected with E. acervulina and highest in those fed OTA contaminated diet (122.2 U/L). OTA induced degenerative changes in kidneys, liver and heart as well as a depletion of lymphoid tissue in the lymphoid organs and a decrease of body weight. Coccidiosis induced only a slight growth depression and duodenal hemorrhages in addition to characteristic duodenal damages. The impairment of kidney function, histopathological changes and general growth depression were stronger when chicks infected with E. acervulina were also given OTA.

Experimental cadmium poisoning in sheep

Pathomorphological investigations of internal organs were made in sheep given sublethal doses of cadmium. Early histological damages in kidneys were established by renal biopsy in some experimental animals. The main histological changes were characterized by granular degeneration in proximal tubules and glomerular endothelial proliferation in kidneys, granular degeneration in hepatocytes, pericapillary oedema and activation of capillary endothelium and Kupffer cells in liver, oedematous and degenerative changes in cerebrum and in the region of Purkinje cells of cerebellum, hyperplasia and proliferation of alveolar epithelium and perivascular or peribronchial mononuclear cell infiltration in lung, and degenerative changes in the medulla and zona glomerulosa of adrenal glands.