A comparative study of high-pressure processing and thermal processing techniques on characteristics and microbial evaluation of orange juice

This study investigates the impact of thermal and high-pressure processing on the quality indicator of orange juice and its storage stability. The pressure was applied at 400 MPa and 600 MPa for 3, 6, and 9 min to process the juice and evaluate the quality of orange juice during 60 days of storage with every 30-day interval. HPP conditions (400 MPa and 600 MPa for 3, 6, and 9 min) did not significantly change the ascorbic acid content of orange juice, in contrast to thermal processing where a crucial decrease in ascorbic content was observed. Ascorbic acid content increased non-significantly from 40.03 to 40.69 (mg/100 g) and 40.79 when applied for 3 and 6 min, respectively, while thermal processing reduced its content up to 33.45 (mg/100 g). Ascorbic acid at 600 MPa was observed at 41.19 (mg/100 g) when treated for 6 min. Carotenoid content was increased when HPP was from 8.6 to 9.14 (mg/100 ml) during 400 MPa for 9 min and 11.65 (mg/100 ml) for 6 min at 600 MPa compared to the corresponding untreated sample and thermally treated sample. The total soluble solids, pH, and acidity of the orange showed stability after HPP and during 60 days of storage. The natural microbiological load (yeast and mold, E-Coli log CFU/ml) was observed below 1 log reduction at 30 days of storage and 2 log reduction during days of storage. This study identified different pressure levels to produce nutritionally and microbiologically stable orange juice compared to thermally processed and untreated samples.