Sugarcane juice is a nutritious, energetic and popular drink in Brazil. For its processing, the
use of supercritical carbon dioxide (SC-CO2) technology as an intervention potentially capable
of rendering high quality products can be considered. This study was undertaken to evaluate
the impact of mild temperatures combined with SC-CO2 on the physicochemical parameters,
color, enzymic inactivation, and microbial reduction in cane juice. Pressures (P) in the range
of 74 to 351 bar, temperatures (T) between 33 and 67 ºC, and dwell times (t) varying from 20
to 70 min were tested in a central composite rotatable design. Seventeen trials were performed.
The pH and soluble solids in the raw cane juice ranged widely (pH 4.6–6.0 / 17.3–25.3 ºBrix).
In the processed juice, variations were 4.4–6.6 and 17.2–25.0 ºBrix. The total color difference
(TCD) between raw and processed juice varied from 2.3 and 12.3. The percentages of
polyphenol oxidase (PPO) and peroxidase (POD) reduction ranged from 1.7 to 74.3%, and
between 0.3 and 51.2, respectively. The log reduction of mesophiles, molds and yeasts, and
lactic bacteria varied from (0 to 4), (0.2 to 3.7) and (0 to 1.9), respectively. Salmonella spp.
counts in the raw juice reached 2.2 logCFU/mL, and it was not detected in the processed juice.
As for the thermotolerant coliforms, counts attained 5.2 logCFU/mL, and log reductions varied
from 0.3 and 2.5. The analysis of effects (p ≤ 0.1) pointed out that the interaction between T
and t (T/t) had a significant effect on mesophiles, molds and yeasts log reduction, pH variation,
and PPO reduction. As for the lactic bacteria reduction, T, P/t and T/t played a significant
effect. P, T, t and T/t had a significant effect on the TDC. The combination of mild temperatures
and SC-CO2 can be potentially used for cane juice preservation.
Rodrigo Petrus is an associate professor in the Food Engineering Department at the University
of Sao Paulo in Brazil. He holds degrees in Food Engineering and Ph.D. in Food Technology.
He has worked as a research fellow in the High Pressure Processing Validation Center at
Cornell AgriTech/USA. His field of investigation includes hurdle technology applied to liquid
food processing and stability. Dr. Petrus currently serves as a scientific director in the Food
Engineers Brazilian Association (ABEA-SP).