Microbiological Evaluation during the Processing of Heart of Palm

Introduction: Brazil is one of the major suppliers of heart of palm in the world. The heart of palm is the large meristem of diverse palm species. It is cut in sticks or pickled and canned for local and international commerce. The hearts of palm are sterile at cutting, but handling exposes them to microorganisms. To ensure the safety, pasteurization must be carried out.  

Purpose: This research was done to evaluate which were the steps that promote the major microbiological contamination during the processing.

Methods: The heart of palm process of a big processing industry had the following steps: I) receipt of the heart of palm; II) removing of the sheaths; III) cutting or picking the shoots; IV) washing; V) arranging in bottle; VI) adding solution; VII) exhausting; VIII) sealing; IX) pasteurization; X) storage. Using specific Petrifilm from 3M, the following microbiological analyses were done after steps III; V; and IX: aerobic mesophilic bacteria, fecal coliform, Staphylococcus spp., mold and yeast.  

Results: Initial population (step III) was: 4.7 x 10⁸ CFU/g for aerobic mesophilic bacteria; 1.2 x 10⁵ CFU/g for fecal coliforms; 2.9 x 10⁵ CFU/g for Staphylococcus spp.; 5.9 x 10⁵ CFU/g for mold and yeast. After step V: 7.7 x 10⁶ CFU/g for aerobic mesophilic bacteria; 2.6 x 10⁵ CFU/g for fecal coliforms; 1.2 x 10⁴ CFU/g for Staphylococcus spp.; 2.2 x 10⁴ CFU/g for mold and yeast. The reductions observed were obtained due the washing step. After pasteurization the population observed was: 2.9 x 10³ CFU/g for aerobic mesophilic bacteria; none fecal coliforms; 3.2 x 10² CFU/g for Staphylococcus spp.; 2.3 x 10³ CFU/g for mold and yeast.

Significance: The results suggest that some improvement must be done during steps I and II to ensure a lower microorganism level in the other steps of the processing.