Parámetros de incubación del starter de Lactobacillus para su aplicación en pan campesino / Incubation parameters of the Lactobacillus starter for application in sourdough bread

RESUMEN El fermento natural o starter es un insumo panadero, que se ha revalorizado, en la actualidad, por sus beneficios y por su aporte de sabor. En este estudio, se determinaron los parámetros de cultivo del starter espontáneo de Lactobacillus, a partir de harina integral, para aplicarlo en la elaboración de pan campesino, en función de sus características sensoriales y mecánicas. Se elaboraron tres starters, para lo cual, se mezcló harina integral con agua, en una proporción de 45,5 y 54,5%, respectivamente; posterior a ello, se fermentaron, espontáneamente, a 20, 24 y 28°C, hasta un pH final de 4, a partir de los cuales, se elaboraron panes campesinos. Los panes fueron evaluados sensorialmente, por un panel de expertos (07), mediante una escala lineal no estructurada de 5 puntos, en cuanto a la forma ovalada, apariencia de la costra, masticabilidad de miga, gusto ácido y apariencia de los alveolos. El pan elaborado con el fermento a 24°C fue seleccionado por los panelistas, debido a que presentó puntajes superiores (p<0,05), en los atributos de apariencia de la costra (4,24), masticabilidad de la miga (5,0), gusto ácido (4,67) y apariencia de los alveolos (4,0). El fermento empleado presentó 79 x 107 UFC g-1 de bacterias acidolácticas. Finalmente, la textura del pan campesino seleccionado fue caracterizada instrumentalmente en términos de dureza (102,09N), gomosidad (43,02N), masticabilidad (37,36N), elasticidad (0,87) y cohesividad (0,42), perfil que se puede emplear como parámetro de calidad, para pan campesino y otras variedades similares.

ABSTRACT The natural ferment or sourdough starter is a bakery input that has been revalued nowadays for its benefits and flavour improve. In this study, the incubation parameters of the spontaneous Lactobacillus starter made with wholemeal flour were determined to be applied in sourdough bread production depending on its sensory and mechanical characteristics. Three starters were made with wholemeal flour mixed with water in a proportion of 45.5 and 54.5% respectively, then were fermented spontaneously at 20, 24 and 28°C until a final pH of 4, from which sourdough breads were produced. The breads were sensory evaluated by a panel of experts (07), using a 5-point unstructured linear scale, in terms of oval shape, crust appearance, crumb chewiness, sourness and alveoli appearance. The bread made with the starter at 24°C was selected because of the higher scores (p<0.05) in the attributes of crust appearance (4.24), crumb chewiness (5.0), sourness (4.67) and alveoli appearance (4.0). The starter used exhibit 79 x 107 CFU g-1 of lactic acid bacteria. Finally, the texture of the selected sourdough bread was characterized in terms of hardness (102.09N), gumminess (43.02N), chewiness (37.36N), springiness (0.87) and cohesiveness (0.42), a profile that can be used as a quality parameter for sourdough bread and other similar varieties.

Isolation and characterization of lactic acid bacteria and yeasts from the Brazilian grape sourdough

Sourdough is a mixture of flour and water fermented by lactic acid bacteria and yeast, with a large use in bakery products. This study was developed with Brazilian grape (Niagara rosada) sourdough obtained from spontaneous fermentation. The aim of this work was to characterize genotypic and phenotypically lactic acid bacteria and yeasts isolated from sourdough. The phenotypic identification for bacteria and yeasts was performed by using the kit API50CHL and 20CAUX and the genotypic characterization was performed by sequencing method. A total of four isolated strains were analyzed in this study. Two of these strains were phenotypically and genotypic identified as Lactobacillus paracasei and one as Saccharomyces cerevisiae. Another sample phenotypically identified as Candida pelliculosa did not show the same identity by sequencing. It shows the need to use phenotypic and genotypic characterization associated for the correct microorganism identification.

Fermento natural é mistura de farinha e água fermentada por bactérias láticas e leveduras, amplamente utilizada em produtos de panificação. Neste estudo desenvolveu-se um fermento natural de uva brasileira (Niagara rosada), obtido a partir de fermentação espontânea. O objetivo deste trabalho foi caracterizar fenotipicamente e genotipicamente bactérias láticas e leveduras isoladas do fermento natural de uva. A identificação fenotípica para bactéria lática e leveduras foi realizada usando os kits API50CHL e 20CAUX e a caracterização genotípica foi realizada pelo método de sequenciamento. Neste estudo, isolaram-se quatro cepas. Duas cepas foram identificadas fenotipicamente e genotipicamente como Lactobacillus paracasei e outra cepa como Saccharomyces cerevisiae. A outra amostra de levedura, identificada fenotipicamente como Candida pelliculosa, não obteve a mesma identidade com a técnica de sequenciamento. Isso mostra a necessidade do uso da caracterização fenotípica e genotípica em associação para a correta identificação do micro-organismo.

Influence of fermentation time on characteristics of sourdough bread

Sourdough is used in the manufacture of numerous baked products. The microorganisms used in this preparation of sourdoughs included two strains from the Lactobacillus paracasei (1 and 2) and two strains from the Saccharomyces cerevisiae group (1 and 2). Samples of raw dough were analyzed for pH, titratable acidity and plate counts and samples of resulting bread were analyzed for pH, titratable acidity and specific volume. The samples were analyzed every 2 h, between 4 and 10 h of fermentation. After 10 hours of fermentation, the lowest values of pH were for dough with LC2 and bread with SC1. Titratable acidity values increased over time, with the highest levels of acidity were found in the dough and bread with yeasts. Lactic acid bacteria showed the highest microbial counts over time. With the exception of SC2, the greatest microbial increases occurred at 10 hours of fermentation. LC1 showed the lowest volume across all time points (p < 0.05). The largest volumes were found in breads after 6 hours of fermentation. SC1 showed the best specific volume values across all times tested.

O fermento natural é usado no processamento de vários produtos de panificação. Os micro-organimos usados no preparo dos fermentos foram duas cepas de Lactobacillus paracasei (1 e 2) e duas cepas de Saccharomyces cerevisiae (1 e 2). Das amostras de massa crua, foi analisado o pH, a acidez titulável e a contagem em placas e das amostras do pão, foi analisado o pH, a acidez titulável e o volume específico. As amostras foram analisadas num intervalo de 2 h, entre 4 e 10 h de fermentação. Ao final, os menores valores de pH foram para a massa crua com LC2 e o pão com SC1. Os valores de acidez titulável aumentaram ao longo do tempo, apresentando os maiores teores de acidez a massa e o pão com leveduras. As bactérias láticas apresentaram as maiores contagens microbiológicas ao longo do tempo. Com exceção de SC2, os maiores crescimentos microbianos foram com 10 h de fermentação. LC1 apresentou menor volume em todas as horas (p < 0.05). Os maiores volumes encontrados nos pães foram com 6 h de fermentação. SC1 apresentou os melhores resultados de volume específico durante todo o período.