Preservation of natural maracuya juice by combined heat and irradiation treatments

The vialibility of natural maracuya juice preservation (Passiflora edulis, Sims.) at the combined treatments. Temperatures of 50, 55 and 60 oC with immersion times between 5 and 20 minutes were applied to the juice (16 Brix) packed in nylon-polyethylene mpouches. Only a treatment at 60 oC during 20 minutes inhibits the growing of all the microorganims present in the juice. Doses up to 5.0 KGy with gamma-radiation are not able to preserve the maracuya juice due the fermentation process occured at Laboratory normal conditions, i,e., 15-20 oC snf 65 per cent R.H. A combined treatment of 60 oC 10 min and doses of 4.0 and 5.0 KGy resulted very effective in inhibiting the microorganism growing and keeping the quality of the natural maracuya juice at least 3 months under the mentioned conditions. The D10 decimal reduction values determined experimentally for mixed microflora present normally in the juice were: 3.9 min for th 60degC tratment; 1.36 KGy for just irradiation and 1.03 KGy for the combinedtreatment. Both, the physico-chemical and organoleptic tests showed no significant difference at p=0.05 between the treated and natural juice