Physico-chemical and microbiological characterization of corn and rice ‘calugi’ produced by Brazilian Amerindian people

Abstract

‘Calugi’ is a fermented porridge that is produced from corn and rice by Javaé Amerindians. Samples of this porridge were chemically and microbiologically characterized. The microbial population was composed of yeasts, aerobic mesophilic bacteria (AMB), lactic acid bacteria (LAB), acetic acid bacteria (AAB) and some enterobacteria. The population of lactic acid bacteria (LAB), acetic acid bacteria (AAB) and yeasts increased slightly during ‘calugi’ fermentation. During the initial fermentation period (12 and 24 h), counts of the bacterial population (LAB, AMB and enterobacteria) and yeast increased. After 48 h of fermentation, the population of mesophilic bacteria was 5.06 log CFU/mL; lactic acid bacteria (LAB), 4.69 log CFU/mL; yeast, 4.37 log CFU/mL; enterobacteria, 3.29 log CFU/mL and acid acetic bacteria (AAB), 3.14 log CFU/mL. During the fermentation process, Lactobacillus plantarum, Streptococcus salivarius, Streptococcus parasanguis, Weissella confusa, Enterobacter cloacae, Bacillus cereus and Bacillus sp. and the yeasts Saccharomyces cerevisiae, Pichia fermentans and Candida sp. were detected by PCR-DGGE. The LAB were dominant during the process and were likely most responsible for the reduction in pH value, which permitted yeast growth. Carbohydrates (70.48 g/L — maltose), alcohols (1.70 g/L — glycerol) and acids (4.56 g/L — acid lactic) were identified by HPLC. Fifteen volatile compounds were identified and quantified by GC-FID. From the fermentation, acetaldehyde, 1-1-diethoxyethane, isobutyl acetate, ethyl acetate, furfuryl alcohol and nonanoic acid were identified, with maximum concentrations of 457.02 μg/L, 73.96 μg/L, 54.03 μg/L, 24.82 μg/L, 755.82 μg/L, 61.85 μg/L, respectively.