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Sugarcane juice has been associated with a short shelf life due to the rapid enzymatic spoilage and microbial fermentation. The evolution of quality attributes of the high pressure processed (HPP)juice (523 MPa/50°C/11 min) was compared with that of conventionally pasteurizedjuice (90°C/5 min), packed in two different packaging materials, viz., ethylene vinyl alcohol (EVOH) and multi-layered (ML-PET) polyethylene terephthalate and stored under refrigerated conditions. The total color difference of the juice samples changed in line with the zero-order kinetics while the changes in the ascorbic acid, total phenols, antioxidant capacity, and enzyme inactivation were well predicted by the first-order kinetics. The sensory acceptability of the HPP juice was superior to pasteurized samples. Under refrigeration, the HPP samples in ML-PET exhibited a shelf life of upto 100 days as against the pasteurized juice, which reported shelf life of 45 days. Practical applications Commercialization of sugarcane juice is limited by its short shelf life in virtue of rapid microbial fermentation and enzymatic browning. The pasteurization of the sugarcane juice has been found to be effective in preserving the juice and this is often accompanied by loss of heat sensitive nutrients and discoloration due non enzymatic reactions. On this front, the high pressure processing is an alternate technique for preservation of the juice for an extended duration. The technology ensures substantial reduction in the microbial load as well as the spoilage enzymes, ensuring minimal effect on the nutrient profile and sensory attributes.

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BACKGROUND: Polyphenol oxidase (PPO) is the main enzyme in sugarcane juice associated with rapid browning and degradation of organoleptic properties. High-pressure processing (HPP) (300-600 MPa) of sugarcane juice in combination with moderate temperatures (30-60 ∘ C) for different processing times (10-25 min) has shown promising results in minimizing PPO activity while preserving the juice's freshness. RESULTS:A maximum PPO inactivation of 98% was achieved at 600 MPa/60 ∘ C/25 min, while the corresponding value for thermal treatment at 0.1 MPa/60 ∘ C was only 66%. The nonlinearity in the inactivation data was well described by the Weibull distribution model with a high adjusted R 2 and reduced 2 values at all levels of pressure and temperature. The PPO inactivation data were fitted at shape parameter, = 1 (log linear) and ≠ 1. A refitted Weibull model was used to predict kinetic parameters such as the inactivation rate constants (k), activation energy (E a ) and activation volume (V a ), which govern PPO inactivation in HPP-treated sugarcane juice. A secondary kinetic model was formulated to predict the k values as a function of pressure (P) and temperature (T), incorporating E a and V a . CONCLUSIONS: Combined high-pressure and temperature processing has been considered a reliable alternative to conventional heat treatment for inhibiting PPO activity in sugarcane juice. While the isothermal inactivation of PPO followed first-order kinetics, inclusion of high pressure resulted in a strong deviation from log linear kinetics. Identification of suitable kinetic models describing these inactivation processes is expected to aid product development and process control of high-pressure processed sugarcane juice.

The efficacy of high‐pressure processing (HPP) on inactivation of indigenous vegetative microorganisms in sugarcane juice was studied under the pressure range of 300–600 MPa for a treatment time of 1 s through 25 min at ambient temperature (30 ± 2 °C). No significant change in pH, total soluble solids (TSS) and titratable acidity were observed in the juice, whereas color variation was significant (p < .05) after HPP treatment. Application of HPP has significantly (p < .05) reduced the vegetative microbial count with the increase in pressure and treatment time. Isobaric destruction of microorganisms followed first‐order kinetics. Among the group of natural microflora studied, coliforms were observed to be more sensitive whereas aerobic mesophiles were least sensitive with the zp value of 846 MPa and the ΔV value of −6.85 × 10−6 m3/mol. High‐pressure treatment of sugarcane juice at 600 MPa/20 min was sufficient to inactivate vegetative microorganisms effectively with minimal changes in physico‐chemical properties of the juice. Practical applications Sugarcane juice is one of the nutritious natural drinks available in South‐Asian countries. The shelf‐life of sugarcane juice is limited due to high incidences of microbial contamination, which begin immediately after extraction. Thermal processing of sugarcane juice at high temperatures and processing times has a detrimental effect on sensory and nutritional qualities of the juice. The application of high‐pressure processing (HPP) has proved to be a promising technology to produce microbial safe sugarcane juice with minimal changes in physico‐chemical properties. HPP technology can provide a breakthrough in the beverage industries, in developing a “ready‐to‐serve” sugarcane juice for the commercialization and marketability of good quality sugarcane juice.

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