Encinos mexicanos, un recurso no maderable con potencial para elaborar bebidas tipo Kombucha

Abstract

O aks (Quercus spp.) are some of the world's most important and abundant trees in nearly all temperate forests of the northern hemisphere. There are two diversity centers for this genus: one is in Southeast Asia, and the other is in Mexico. Studies on the use of oak have mainly highlighted its timber applications. However, its non-timber value is still unappreciated. Ethnobotanical tradition shows infusions from Quercus leaves, alone or in combination with other plants, which have anticarcinogenic effects in gastric cancer patients. Sensorial studies on oak herbal infusions have shown that a higher phenolic content decreases their acceptability. Therefore, a significant alternative for encouraging use of herbal teas is fermentation with the Kombucha culture (black tea fungus). Kombucha drink is reported as a potential health promoter. It is a slightly acidic beverage from fermentation of sweetened black tea with Kombucha consortium, which consists mainly of acetic acid bacteria and yeasts. The phenolic composition and content gradually changes over fermentation time, producing a beverage rich in antioxidants. Metabolic conversion of polyphenols may be due to glucuronidation of original flavonoid compounds. This process enhances the bioavailability of phytochemicals, which include a wide range of bioactive ellagitannins and flavonoids, in oaks. ResumenL os encinos (Quercus spp.) son algunos de los árboles más importantes y abundantes en casi todos los bosques templados del hemisferio norte. El sudeste asiático y México destacan como centros de diversidad del género. La investigación sobre el encino se ha enfocado principalmente en sus aplicaciones maderables, siendo poco reconocido su valor como recurso no maderable. La tradición etnobotánica muestra que las infusiones de hojas de encino, solas o combinadas con otras plantas, presentan efectos contra el cáncer gástrico; sin embargo, el análisis sensorial de las infusiones ha mostrado relación inversa entre su aceptabilidad y su contenido fenólico. Por lo anterior, el hongo del té (Kombucha) es una alternativa para fermentar infusiones de encino, mejorando su aceptabilidad y carácter profiláctico. La bebida Kombucha es ligeramente ácida debido a que se prepara a partir de té negro endulzado que es fermentado por el consorcio microbiano Kombucha. El consorcio se forma por bacterias ácido acéticas y levaduras que cambian gradualmente la composición fenólica del sustrato, produciendo una bebida rica en antioxidantes. La conversión metabólica de los polifenoles puede deberse a su glucuronidación, que es un proceso que libera y realza la biodisponibilidad de los fitoquímicos presentes en el encino, incluyendo elagitaninos y flavonoides bioactivos.

Antioxidants in Oak (Quercus sp.): Potential Application to Reduce Oxidative Rancidity in Foods

“…Because they are economical, they have become one of the most profitable woods for this industry [ 13 , 21 ]. In Mexico, around 150 species have been reported, representing the second most important forest resource and used mainly for manufacturing handicrafts, firewood, and charcoal [ 74 , 75 ].…”

“…Phenolic compounds are the most abundant and have been found to have high antioxidant capacity, with gallic acid, ellagic acid, and ellagitannins identified as potent antioxidant compounds [ 21 ]. In vitro and in vivo studies of oak extracts have demonstrated high antioxidant capacity, with variations in their potency depending on the species, part of the oak used, and external factors such as seasonal changes and level of maturity [ 13 , 43 , 75 , 77 ]. Further research can be conducted to explore the chemical composition of different Quercus species to determine the best oak parts for extraction and to investigate the functional properties and potential health benefits of these extracts when applied in food systems.…”

“…In the case of extracts derived from oak wood, these contain compounds such as ellagitannins and volatile organic compounds, presenting aromas and flavors described as coconut, vanilla, nutty, and toasty [ 16 , 21 ]. In the case of extracts from oak leaves, it has been described that the high content of polyphenols can give astringent flavors [ 75 ]. When added to food systems, these compounds interact with food components such as fats and proteins, leading to changes in the food’s aroma and taste [ 83 ].…”

“…Toxicological studies on foods added with oak extracts have not been carried out; however, in many places, infusions and fermented beverages of the leaves are consumed for medicinal purposes without apparent adverse effects [ 13 , 14 , 75 ]. The current knowledge on the toxicity of oak extracts is limited to studies performed on a cellular level and in rats.…”

Cocoa Mucilage: A Novel Substrate for Fermented Tea-Based Beverages

“…Yeasts such as Schizosaccharomyces pombe and Saccharomycodes ludwigii have also been identified [19,20]. Several industrial sectors benefit from SCOBY, such as the food industry, biotechnological processes, and biomedicine [21][22][23].…”