Degradation of lignocellulosic matrix of oilseed cakes by solid-state fermentation: fungi screening for enzymes production and antioxidants release.

BACKGROUND: Vegetable oils are yearly produced in large amounts generating solid by-products, the oilseed cake (OC). OCs are lignocellulosic materials that have been used for animal feed with some limitations due to high fibre content from the plant cell walls. Biotechnological processes can help to overcome these limitations and contribute to up-grading such by-products, enhancing their nutritional value as feed ingredients. RESULTS: All fungal species were able to decrease neutral detergent fibre and acid detergent fibre in all by-products. Additionally, relevant enzymes were produced by the three fungi studied resulting in an improved antioxidant capacity of all fermented OCs. Aspergillus niger led to the highest activity of cellulase (109 U g-1 ), xylanase (692 U g-1 ) and protease (157 U g-1 ) per dry OC matter and to the recovery of an extract rich in antioxidants, with the highest scavenging potential of free radicals and superoxide anion, iron chelation ability and reducing power. Rhyzopus oryzae produced the highest activity of ß-glucosidase (503 U g-1 ) and led to the highest liberation of total phenolic content (TPC). Principal components analysis showed that extracts with high antioxidant potential were obtained in solid-state fermentation (SSF) with high enzymatic activity. A positive correlation was established between the action of ß-glucosidase and TPC. CONCLUSION: Within the same bioprocess it was possible to improve the nutritional value of OCs and to obtain relevant bioactive compounds such as lignocellulosic enzymes and phenolic compounds with antioxidant potential, resulting in a significant improvement of already valuable by-products with commercial interest for animal feed. © 2021 Society of Chemical Industry.

Effect of carob variety and roasting on the antioxidant capacity, and the phenolic and furanic contents of carob liquors.

BACKGROUND: The production of the traditional carob liquor from Algarve (Portugal) depends on numerous factors such as carob processing, variety and maceration conditions. An experimental design with 36 runs was created to evaluate the effect of the roasting temperature, particle size, variety of carob and time of maceration on several parameters of carob liquors as gallic acid and total phenolic content, the furanic composition (furfural and 5-(hydroxymethyl)furfural), browning index and in vitro antioxidant capacity. RESULTS: The results revealed that carob variety was the independent variable with the greatest effect on antioxidant capacity, total phenolic and gallic acid content. In particular, AIDA liquors presented the highest results, mainly those prepared with unroasted carob. Meanwhile, Galhosa and Mulata liquors showed the greatest concentrations when the carob pulp was roasted at 150 °C. The furanic composition and browning index were greatly influenced by the carob roasting degree. CONCLUSION: The levels of the main toxic furanics present in carob liquors, furfural and 5-(hydroxymethyl)furfural, suggest a safe consumption of these beverages even in samples of carobs with the maximum roasting degree. The smallest carob particle size favoured the highest phenolic extraction, while the longest maceration periods decreased the concentration of the toxic furanic compounds studied. © 2018 Society of Chemical Industry.

Mediterranean agro-industrial wastes as valuable substrates for lignocellulolytic enzymes and protein production by solid-state fermentation.

BACKGROUND: Mediterranean agro-food industries (such as wineries, breweries and olive mills) dispose of great amounts of waste. This generates environmental problems, and the waste has a low nutritional value for use as animal feed. In this sense, solid-state fermentation (SSF) can increase the nutritional value of these wastes and simultaneously produce lignocellulolytic enzymes. RESULTS: All fermented wastes were enriched in protein by the three fungi studied. Aspergillus ibericus was the fungus with the biggest increase of protein, which ranged from 1.4 times to 6.2 times with respect to unfermented wastes. Likewise, A. ibericus achieved the maximum cellulase and xylanase activities. The relationships among substrates composition, fungi used and SSF performance were evaluated by principal components analysis. The high content of cellulose and hemicellulose favoured lignocellulolytic enzymes production, and the phenolics content was negatively correlated with enzymes production and with the increase of protein by SSF. Furthermore, the scanning electron microscopy analysis showed the growth of fungi over solid wastes, the formation of conidiophores and the changes in their structures. CONCLUSION: The nutritional value of Mediterranean wastes was improved and other value-added products such as lignocellulolytic enzymes were produced in the same process, which could facilitate the efficient reuse of these wastes. © 2018 Society of Chemical Industry.

Fermentation kinetics and chemical characterisation of vino tostado, a traditional sweet wine from Galicia (NW Spain).

BACKGROUND: Grapes after harvesting are air dried and pressed in order to concentrate sugars, acids and flavour compounds to produce vino tostado (toasted wine), a wine with intense aroma and flavour notes and high residual sugar concentration. In order to get a better knowledge of the difficulties involved, several fermentations were conducted at 12 and 28 degrees C using 0, 15 and 30 g hL(-1) ammonium sulfate and 0, 25 and 50 g hL(-1) exogenous commercial yeast (Saccharomyces cerevisiae var. bayanus) to study the kinetics of sugar consumption and ethanol, acetic acid and glycerol production. RESULTS: Fermentation kinetic parameters were calculated and metal concentrations and antioxidant activity were analysed. CONCLUSION: The spontaneous fermentation at 12 degrees C and all fermentations conducted with the commercial yeast gave vino tostado of adequate quality, while the spontaneous fermentation at 28 degrees C was sluggish. High-temperature fermentations led to sweeter wines with higher volumetric productivities, although low-temperature fermentations produced better wines in terms of higher glycerol and lower acetic acid levels. Fructose was the only sugar to be consumed during spontaneous fermentations, while both glucose and fructose were consumed during fermentations of the inoculated musts, with preference for each monosaccharide depending on temperature.

Ancient origin of a Western Mediterranean radiation of subterranean beetles.

BACKGROUND: Cave organisms have been used as models for evolution and biogeography, as their reduced above-ground dispersal produces phylogenetic patterns of area distribution that largely match the geological history of mountain ranges and cave habitats. Most current hypotheses assume that subterranean lineages arose recently from surface dwelling, dispersive close relatives, but for terrestrial organisms there is scant phylogenetic evidence to support this view. We study here with molecular methods the evolutionary history of a highly diverse assemblage of subterranean beetles in the tribe Leptodirini (Coleoptera, Leiodidae, Cholevinae) in the mountain systems of the Western Mediterranean. RESULTS: Ca. 3.5 KB of sequence information from five mitochondrial and two nuclear gene fragments was obtained for 57 species of Leptodirini and eight outgroups. Phylogenetic analysis was robust to changes in alignment and reconstruction method and revealed strongly supported clades, each of them restricted to a major mountain system in the Iberian peninsula. A molecular clock calibration of the tree using the separation of the Sardinian microplate (at 33 MY) established a rate of 2.0% divergence per MY for five mitochondrial genes (4% for cox1 alone) and dated the nodes separating the main subterranean lineages before the Early Oligocene. The colonisation of the Pyrenean chain, by a lineage not closely related to those found elsewhere in the Iberian peninsula, began soon after the subterranean habitat became available in the Early Oligocene, and progressed from the periphery to the centre. CONCLUSIONS: Our results suggest that by the Early-Mid Oligocene the main lineages of Western Mediterranean Leptodirini had developed all modifications to the subterranean life and were already present in the main geographical areas in which they are found today. The origin of the currently recognised genera can be dated to the Late Oligocene-Miocene, and their diversification can thus be traced to Miocene ancestors fully adapted to subterranean life, with no evidence of extinct epigean, less modified lineages. The close correspondence of organismal evolution and geological record confirms them as an important study system for historical biogeography and molecular evolution.