RESUMEN
Biorefineries have attracted significant attention from the scientific community and various industrial sectors due to their use of unconventional biomass sources to produce biofuels and other value-added compounds. Various agro-industrial residues can be applied in biorefinery systems, making them economically and environmentally attractive. However, the cost, efficiency, and profitability of the process are directly affected by the choice of biomass, pre-treatments, and desired products. In biorefineries, the simultaneous production of different products during processing is a valuable approach. Chemical, physical, biological, or combined treatments can generate numerous compounds of high commercial interest, such as phenolic compounds. These treatments, in addition to modifying the biomass structure, are essential for the process's viability. Over the years, complex treatments with high costs and environmental impacts have been simplified and improved, becoming more specific in generating high-value resources as secondary outputs to the main process (generally related to the release of sugars from lignocelluloses to produce second-generation ethanol). Innovative methods involving microorganisms and enzymes are the most promising in terms of efficiency and lower environmental impact. Biorefineries enable the use of varied raw materials, such as different agro-industrial residues, allowing for more efficient resource utilization and reducing dependence on non-renewable sources. In addition to producing low-carbon biofuels, biorefineries generate a variety of high-value by-products, such as packaging materials, pharmaceuticals, and nutritional ingredients. This not only increases the profitability of biorefineries but also contributes to a circular economy.
RESUMEN
Research background: Research into bacterial cellulose production has been growing rapidly in recent years, as it has a potential use in various applications, such as in the medical and food industries. Previous studies have focused on optimising the production process through various methods, such as using different carbon sources and manipulating environmental conditions. However, further research is still needed to optimise the production process and understand the underlying mechanisms of bacterial cellulose synthesis. Experimental approach: We used Plackett-Burman and Box-Behnken experimental designs to analyse the effect of different factors on bacterial cellulose production. The fermentation kinetics of the optimised medium was analysed, and the produced cellulose was characterised. This approach was used because it allows the identification of significant factors influencing bacterial cellulose growth, the optimisation of the culture medium and the characterisation of the produced cellulose. Results and conclusions: The results showed that higher sucrose concentrations, higher kombucha volume fractions and a smaller size of the symbiotic culture of bacteria and yeast were the most important factors for the improvement of bacterial cellulose production, while the other factors had no relevant influence. The optimised medium showed an increase in the concentrations of total phenolic compounds and total flavonoids as well as significant antioxidant activity. The produced pure bacterial cellulose had a high water absorption capacity as well as high crystallinity and thermal stability. Novelty and scientific contribution: The study makes an important scientific contribution by optimising the culture medium to produce bacterial cellulose more productively and efficiently. The optimised medium can be used for the production of a kombucha-like beverage with a high content of bioactive compounds and for the production of bacterial cellulose with high crystallinity and thermal stability. Additionally, the study highlights the potential of bacterial cellulose as a highly water-absorbent material with applications in areas such as packaging and biomedical engineering.
RESUMEN
The plant Camellia sinensis is the source of different teas (white, green, yellow, oolong, black, and pu-ehr) consumed worldwide, which are classified by the oxidation degree of their bioactive compounds. The sensory (taste, aroma, and body of the drink) and functional properties of teas are affected by the amount of methylxanthines (caffeine and theobromine), amino acids (l-theanine) and reducing sugars in their composition. Additionally, flavan-3-ols, mainly characterized by epicatechins, catechins, and their derivatives, represent on average, 60% of the bioactive compounds in teas. These secondary metabolites from teas are widely recognized for their antioxidant, anti-cancer, and anti-inflammatory properties. Thus, Camellia sinensis extracts and their isolated compounds have been increasingly used by the food industry. However, bioactive compounds are very susceptible to the oxidation caused by processing and degradation under physiological conditions of gastrointestinal digestion. In this context, new approaches/technologies have been developed for the preservation of these compounds. This review presents the main stages involved in production of Camellia sinensis teas following a description of their main bioactive compounds, biological properties, stability and bioaccessibility. Besides, and updated view of Camellia sinensis teas in the field of food science and technology was provided by focusing on novel findings and innovations published in scientific literature over the last five years.