Estudio de la viabilidad de Lactobacillus casei Shirota en una gelatina de pitaya (Stenocereus griseus H.)

Abstract

Pitaya (Stenocereus griseus H.) is a Mexican temporary fruit –only harvested in may- of columnar cacti, it is also known as “pitaya de mayo”, which has been reported to have an important antioxidant capacity due to the high total phenolic content and the presence of the pigments betalains composed by betacianins and betaxanthins. Lactobacillus casei Shirota is an acid-lactic bacteria considered as a probiotic which has beneficial health effects. The aim of this work was to establish the viability of Lactobacillus casei Shirota in a pitaya’s jelly. Pitayas were acquired at the market “Central de Abastos”. The pulp was conserved in zip-lock bags at – 20ºC. The juice obtained with Braun blender was filtered to eliminate the seeds and characterized with the following determinations by triplicate pH, ºBrix (soluble solids), citric acid content and total antioxidant capacity by Fogliano’s method. To elaborate jellies 12% of sucrose, 3.5% of gelatin, 50% of pitaya’s juice previously treated at 92ºC for 26s in order to eliminate pitaya’s endogenous microorganisms were mixed. Then the probiotic microorganism was quantified by Mc Farland’s method to add 1 x 10 9 CFU/mL to the jelly, when the temperature was 30ºC. The probiotic was previously isolated from Yakult and also identified as gram-positive and catalase negative. Pitaya’s jellys were analyzed each 48 h by triplicate measuring pH, ºBrix and viable cells counts were determined by the standard plate method with MRS after 48h of incubation at 35ºC. The pitaya’s juice characterization was pH=5.8 ± 0.114, ºBrix = 10.26 ±.0.115, 0.15 ± 0.07 for the citric acid content and the total antioxidant capacity was 162.5 ± 18.11 molTrolox/mL. The viability of the microorganism at the jelly after 3 weeks was 1 x 108 CFU/g, so the jelly was still considered as a probiotic product because this value is between the established ranges for probiotics which are1 x 106 – 1 x 108 CFU/g.. It was observed that pitaya’s jelly was capable to provide good support keeping the viability of the probiotic microorganism.