Incorporación de los cultivos bioprotectores en aceitunas envasadas en formato doy-pack

Abstract

[ES] El envasado de aceitunas en doy-pack es uno de los formatos de venta que más ha aumentado en el mercado durante los últimos años, por su comodidad y ligereza, siendo uno de los formatos de comercialización más interesantes para los consumidores, distribuidores y las empresas de elaboración. Sin embargo, la aplicación de calor como método de conservación de las aceitunas en este tipo de formato provoca cierta pérdida en la funcionalidad y propiedades tecnológicas del envase y puede llegar a afectar a la calidad nutricional y sensorial del producto. Es por ello, que la industria busca estrategias alternativas al empleo de altas temperaturas, que sean menos agresivas con el producto, y que requieran un menor coste energético. En este contexto, el objetivo del presente trabajo es desarrollar un producto de aceitunas de mesa en formato doy-pack, donde la estabilidad del producto se consiga gracias a la incorporación de cultivos bioprotectores, evitando el uso de tratamientos térmicos. Para ello, se aislarán e identificarán levaduras responsables del deterioro de las aceitunas de mesa, con el objetivo de establecer una estrategia de bioconservación dirigida a esta población microbiana. Para la conservación del producto, se emplearán las mismas bacterias ácido lácticas que son utilizadas como cultivos starter de la fermentación. En este trabajo, se empleará Lactobacillus plantarum obtenido de un starter comercial, que se hará crecer bajo condiciones controladas antes de su incorporación al producto final. Las aceitunas de mesa serán inoculadas con las levaduras alterantes seleccionadas y el cultivo bioconservador se adicionará al producto a través de su líquido de gobierno. Las muestras de aceitunas se envasarán en bolsas doy-pack y se almacenarán a temperatura ambiente, realizándose muestreos periódicos para analizar su calidad microbiológica, propiedades fisicoquímicas y atributos sensoriales durante el almacenamiento.

[EN] The packaging olives in doy-pack is one of the sales formats that has increased the most in the market in recent years, due to its convenience and lightness, and is one of the most interesting marketing formats for consumers, distributors and processing companies. However, the application of heat as a method of preserving olives in this type of format causes a certain loss in the functionality and technological properties of the packaging and can affect the nutritional and sensory quality of the product. In this way, the industry is looking for alternative strategies to the use of high temperatures. In this context, the aim of the present work is to develop a table olive product in doy-pack format, where the stability of the product is achieved thanks to the incorporation of bioprotective cultures. For this purpose, the effectiveness of L. plantarum obtained from a commercial starter, as a biopreservative agent, against a strain of S. cerevisiae, isolated from a spoiled batch of table olives, has been evaluated. In the first phase of the work, the effect of salt and pH values on the growth of both microorganisms was studied. The results obtained showed the sensitivity of the spoilage yeast to acid pH values; however, the starter used as a biocontrol agent was not affected by the pH or the level of salt in the medium. In the second phase of the work, the aim was evaluating the effectiveness of this fermentation starter culture to prevent spoilage caused by the presence of spoilage yeasts in table olives, containers of doy-pack olives were inoculated with the spoilage yeast at different concentrations and with the starter culture, evaluating the physicochemical and microbiological parameters of the product during storage. The results obtained showed a reduction in both microbial populations during storage, especially in the case of the yeasts. In the samples inoculated with the fermentation starter, the population of lactic bacteria was in all cases higher than those observed in the samples inoculated only with yeasts and in the control samples, which shows the capacity of these bacteria to survive under the conditions of the final product. The results obtained indicate that the use of the fermentation starter culture has not been lethal for table olive spoilage yeasts. However, the ability of this microorganism to survive under the conditions of the product could be sufficient to allow the generation of bacteriocins associated with some strains of L. plantarum, thus contributing to the preservation of the final product.