The aim of this work was to establish thermal processing conditions for banana puree in retor pouches (130 x 170mm). The fruits were selected, blanched in boiling water for 5min., finished (0,033 inch) mesh and vacuum-packaged in 25mmHg with 2,7ml residual air/pouch. After the pouches were processed without agitation in horizontal position at 115°C/158 Kpa over-pressure in water total immersion. The holding process time was 7,5min. Initially Clostridium butyricum was used as target organism for the thermal process, however the banana puree is situated in pH limit area of (4,6) for low acid foods, favouring the Clostridium botulinum growth. Its heat resistance was estimated through of the equation 1 (PFLUG, 1985) and compared with C. butyricum. Though the D115°C values for C. butyricum and C. botulinum were similar (0,183 min and 0,236 min, respectively), C. botulinum higher compared to C. butyricum. The F121,1°C applied was 0,64 min to obtain 12 decimal reductions calculated by PFLUG (1985) and verified by the general method. This value was only considerated for the heating phase. The value of F121,1°C = 0,27 min (29,5%) determinated for cooling phase, was used as safety factor. Average values of the heating rate rate parameter fh and the lag factor were: fh=6,8min. and jh=0,48. For the cooling phase the average values were: fc=17,4min. and jc=1,3. After 15 days/37°C incubation, no abnormal conditions were noted in the 36 processed pouches. This is an indicative that the process was satisfactory from the microbiological standpoint.
banana puree; Clostridium butyricum; Clostridium botulinum; retortable pouch; rotative retort
