The potential use of supercritical carbon dioxide in sugarcane juice processing

Sugarcane juice is a nutritious and energetic drink. For its processing, the use of supercritical carbon dioxide (SC-CO2) technology as an intervention potentially capable of rendering a high quality product can be considered. This study evaluated the combined effect of SC-CO2 and mild temperatures, primarily aiming for the reduction of endogenous microorganisms and enzymes in sugarcane juice (pH ~5.5). Pressures ranging from 74 to 351 bar, temperatures between 33 and 67 °C, and holding times between 20 and 70 min were tested in a central composite rotational design across 17 trials. Counts of aerobic mesophiles, molds and yeasts, lactic acid bacteria and coliforms at 45 °C, polyphenol oxidase (PPO) and peroxidase (POD) activities, and color parameters were measured in freshly extracted and processed samples. Fresh juice pH ranged 4.6–6.0 and processed 4.6–6.3. Decimal reductions achieved varied between 0.1–3.9 (mesophiles), 2.1–4.1 (molds and yeasts), 0.0–2.1 (lactic acid bacteria), and 0.3–2.5 (coliforms). PPO reductions ranged 3.51%–64.18% and POD 0.27%–41.42%. Color differences (ΔE*) between fresh and processed samples ranged 2.0–12.3. For mesophiles, molds/yeasts reduction, and soluble solids variation, no variables or interactions were significant. For PPO reduction, only time (t) was significant; for POD reduction, temperature (T), time (t), and their interaction were significant. For pH variation, pressure (P) and the T×t interaction were significant. P, T, t, and T×t significantly affected color. The combination of mild temperatures and SC-CO2 can be potentially used for cane juice preservation.