Revalorización de las lías del cava como prebiótico y para mejorar la seguridad de derivados cárnicos fermentados

Abstract

Las lías del cava son un subproducto vitivinícola que consiste en células no viables de Saccharomyces cerevisiae. Su composición rica en ß-glucanos y manano- oligosacáridos (MOS) podría dar lugar a una mejor implantación de las bacterias responsables de la fermentación y un mayor y más rápido descenso del pH que, en último término, reduciría el riesgo de desarrollo de posibles microorganismos patógenos. Además, las lías contienen sustancias procedentes del cava, como compuestos fenólicos, que podrían también ejercer o potenciar este efecto antimicrobiano. Por otra parte, la fibra de las lías del cava podría favorecer el crecimiento selectivo de bacterias probióticas, promoviendo así una mejora de la microbiota intestinal y, por extensión, de la salud humana.

Actualmente, las lías son el segundo subproducto generado en la producción del cava con una producción estimada de aproximadamente 200 toneladas anuales. A pesar de este gran volumen generado, y de su interesante composición, hasta el momento han recibido poca atención. En este contexto, esta tesis doctoral plantea como objetivo general estudiar una nueva estrategia de revalorización de las lías del cava, tanto como ingrediente con una aplicación en seguridad alimentaria como por su carácter prebiótico.

Desde el punto de vista de la seguridad alimentaria, se evaluó el efecto promotor de lías del cava en el crecimiento de diferentes especies de BAL comúnmente utilizadas como cultivos iniciadores, tanto in vitro como en derivados cárnicos fermentados. Los estudios in vitro mostraron un efecto promotor del crecimiento de ciertas cepas de Latilactobacillus sakei y Latilactobacillus curvatus, siendo este efecto dosis y cepa dependiente. De entre las diferentes proporciones ensayadas, la adición de un 5% de lías produjo los mayores recuentos de BAL. En derivados cárnicos fermentados, la adición de un 5% de lías se tradujo en una mayor acidificación, aunque los recuentos de BAL no se vieron afectados de manera significativa.

También se estudió el efecto antimicrobiano de las lías del cava y de su extracto fenólico frente a bacterias patógenas de origen alimentario en derivados cárnicos

Cava lees are a winery by-product consisting of non-viable cells of Saccharomyces cerevisiae. Their richness in ß-glucans and mannan-oligosaccharides (MOS) could lead to a better implantation of bacteria responsible for fermentation and a higher and faster reduction in pH, which would ultimately reduce the risk of foodborne pathogens in products such as dry-fermented sausages. In addition, the lees contain bioactive substances present in cava, such as phenolic compounds, which could also exert or enhance this antimicrobial effect. On the other hand, the fibre in cava lees could favour the selective growth of probiotic bacteria, thus benefitting intestinal microbiota and human health.

Lees are currently the second most important by-product generated by the cava industry, with an estimated production of approximately 200 tons per year. Yet despite this large volume, and their interesting composition, cava lees have so far attracted little attention. In this context, the general objective of this doctoral thesis was to study a new strategy for the revaluation of cava lees, both as an ingredient with application in food safety and as a prebiotic.

From a food safety point of view, the growth-promoting effect of cava lees on different LAB species commonly used as starter cultures was evaluated, both in vitro and in dry-fermented sausages. In vitro studies showed a growth-promoting effect on certain strains of Latilactobacillus sakei and Latilactobacillus curvatus, in a dose- and strain-dependent manner. Among the different proportions tested, the addition of 5% lees produced the highest LAB counts. In dry-fermented sausages, the addition of 5% lees resulted in greater acidification, although LAB counts were not significantly affected.

The antimicrobial effect of cava lees and a derived phenolic extract against foodborne pathogenic bacteria in dry-fermented sausages was also studied. Cava lees significantly inhibited the growth of Salmonella and Listeria monocytogenes, with an effectiveness similar to that obtained when the starter culture L. sakei CTC494 was added. In addition, the combination of cava lees and the starter culture had a synergistic and bactericidal effect against Salmonella. The phenolic extract from the cava lees slightly reduced Salmonella counts in the finished product but had no anti-Listeria effect.

Besides the antimicrobial effect, it was also proposed to study whether the addition of cava lees or a derived phenolic extract reduces the formation of biogenic amines in this type of fermented products. The addition of cava lees to dry-fermented sausages significantly reduced the contents of cadaverine and putrescine throughout the ripening process, with reduction percentages in the finished product of over 60%. The phenolic extract of the cava lees was also capable of significantly reducing the levels of these diamines, although in more moderate percentages.

Finally, within the framework of this doctoral thesis, the prebiotic effect of cava lees on the growth of probiotic bacteria was also evaluated in vitro. Supplementation with 5% cava lees enhanced the growth and/or survival of some probiotic strains of Lactiplantibacillus plantarum, Limosilactobacillus fermentum and Lacticaseibacillus casei.