Sour Starch Research Articles

Lactobacillus manihotivorans sp. nov., a new starch-hydrolysing lactic acid bacterium isolated during cassava sour starch fermentation.

Two Lactobacillus strains were isolated from sour cassava starch fermentation. The cells were Gram-positive, catalase-negative, non-spore-forming, non-motile rods. They produced only L(+)lactate and were homofermentative. Growth occurred at pH values of 5.0-7.0 and optimum growth occurred at pH 6.0. Growth was positive at 15 and 45 degrees C. The DNA G + C content was 48.4 +/- 0.2 mol%. Sequence analysis of the 16S rRNA gene revealed that strains OND 32T and YAM 1 clustered with, but were separate from Lactobacillus casei-related taxa. Protein pattern and sequence analyses of the 16S rRNA gene confirmed that the two new isolates represent a new Lactobacillus species, for which the name Lactobacillus manihotivorans is proposed; strain OND 32T is the type strain of this species.

Efeito do teor de água, amilose, amilopectina e grau de gelatinização no crescimento do biscoito de amido de mandioca obtido por fermentação natural

O amido de mandioca, assim como o amido de araruta, modificado por fermentação natural, quando formulado com água, sal e gordura vegetal hidrogenada para produzir o biscoito de "polvilho azedo", tem a propriedade de se expandir durante a cocção, como se nessa formulação existisse um agente aerante. O produto final obtido, tem uma estrutura alveolar, crocante e de baixa densidade. Pouco se conhece a respeito do mecanismo que envolve essa expansão e sobre os fatores que interferem na mesma. No presente trabalho, investigamos a influência do teor de água, o efeito da pré-gelatinização do amido fermentado e a adição de amilose e de amilopectina no crescimento do biscoito. O tempo de formação do biscoito, demonstrou ser altamente dependente do teor de água presente na sua formulação. A gelatinização total do amido modificado por fermentação, parece destruir completamente suas propriedades de expansão, pois não foi observado crescimento do biscoito com uma formulação padrão contendo apenas amido totalmente gelatinizado. Biscoitos formulados com amilose ou amilopectina em substituição ao amido fermentado, apresentaram baixo grau de expansão quando comparados ao padrão.

Original properties of ropy strains of Lactobacillus plantarum isolated from the sour cassava starch fermentation

C. FIGUEROA, A.M. DAVILA AND J. POURQUIÉ 1997. Sour cassava starch is the result of a lactic fermentation of raw cassava starch followed by sun drying. Lactobacillus plantarum strains are commonly isolated from this fermentation. Among them, a particular group of strains has been characterized by a strong ropy phenotype, the production of a thickening factor under submerged cultures conditions, a low nutritional requirement for organic nitrogen and an absence of amylolytic activity. However, these strains have been shown to thrive on starch, through commensalistic interactions with amylolytic lactic acid bacteria. These results explain the frequent occurrence of ropy, non-amylolytic strains in sour starch fermentation, and support the hypothesis of exopolysaccharides production during this fermentation.

Lactic acid bacteria of the sour cassava starch fermentation

In Brazil and Colombia, ‘sour starch’ is traditionally obtained by a submerged lactic fermentation of crude cassava starch followed by sun drying. It is used by local bakers to prepare breadlike products which display the same expanded crumb texture as in wheat bread. In this process, suspended starch is settled down and left aside for a few weeks under anaerobic conditions where natural lactic populations develop. Three collections of clones isolated from local fermentations have been identified using the API procedure and further characterized. Most of them belong to different species of Lactobacillus. Many display a ropy phenotype, typical for exopolysaccharide (EPS) excretion. A possible role of these EPS in the special properties of sour starch is discussed.

SOUR CASSAVA STARCH PRODUCTION: A PRELIMINARY STUDY

ABSTRACTSour cassava starch is produced in Colombian rural areas by traditional small‐scale technology, which includes a 20–30 days fermentation stage. A study was carried out with the purpose of analyzing the fermentation mechanisms, in an attempt to shorten the above mentioned step. Samples taken from five plants and produced by acid treatment in the laboratory, were evaluated. Results showed that lactic acid bacteria and yeast are involved. Sweet, sour, and acid‐treated starches showed differences in molecular weights and in the surface appearance, under SEM. Although acid‐treated and sour starches showed similar amylogram curves, only the latter produces good specific volume and crumb structure in a baked product called “pan de yuca.”