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The new global trends for consuming natural products rich in bioactive compounds and health-promoter phytochemicals have increased the modern consumer's interest in fruit and vegetable juices. But, the current technologies based on thermal treatments reduce the nutritional value and degrade sensory attributes of these products in relation to the fresh-like juices. Supercritical carbon dioxide (SC–CO 2) technology has emerged as a potential non-thermal technology for the inactivation of spoilage and pathogenic microorganisms and endogenous enzymes responsible for the deterioration of fruit and vegetable juices. Likewise, non-thermal SC-CO 2 processing can preserve the compounds associated with beneficial health effects besides maintaining sensory attributes. Thus, the effects of the SC-CO 2 technology on the microbial and enzymatic inactivation, nutritional compounds, physicochemical properties, sensory attributes and shelf-life of the fruit and vegetable juices are discussed. SC-CO 2 technology is a promising technique for the processing of fresh fruit and vegetable juices in a non-thermal way. SC-CO 2 processing is able to inactivate microbial and enzymatic load of plant-based juices in the temperature range of 35–55 °C and pressure range of 10–60 MPa. SC-CO 2 treated juices are sensorially similar to the fresh-like products with their nutritional value and physicochemical characteristics very close to the unprocessed juices. Under cold storage conditions, the juices stabilized by SC-CO 2 treatment achieved a microbial shelf-life of at least 20 days with quality attributes of freshly juice, depending on their processing parameters and type of juice. However, additional studies are required to perform process optimization, exploring the synergism among its main variables in the same way that economic viability studies are needed. • Supercritical carbon dioxide technology as a non-thermal process was reviewed. • Nutritional compounds, sensory attributes, and shelf-life of natural juices were discussed. • Recent advances in microbial and enzymatic inactivation were summarized. • This review highlighted advances on the non-thermal processing of plant-based juices. [ABSTRACT FROM AUTHOR]

This study investigated the effect of different states of CO 2 on the activity and structural modification of purified polyphenol oxidase (PPO) from apple juice. CO 2 in critical and supercritical states strongly inhibited the PPO activity up to 64.88% and 3.20%, respectively. Dynamic light scattering analysis showed that the two peaks depolymerised into three peaks in the critical state, demonstrating the dissociation and aggregation of small particles. Circular dichroism analysis revealed that the secondary structure deformed because of the loss of α-helix contents in the critical and super critical CO 2 states. Fluorescence intensity dramatically decreased to 251.3 (λ max 312) in the critical state, showing unfolding of PPO molecules thereby resulting in quenching and blue shifting of λ max. Electrophoresis indicated that large molecular aggregates did not run into the gel at supercritical state. Hence, HP-CO 2 treatment in critical and super critical states could induce the aggregation, deformation and structural changes which might be the causes of PPO inactivation. "Polyphenol oxidation (PPO) is the enzyme that initiates the browning reaction and deteriorates the quality of fruit juices". High pressure carbon dioxide (HP-CO 2) technology is a promising technique to obtain high quality apple juices with low enzyme activity. This study analyzed the effects of different states of carbon dioxide gases under HPCD on the activity, aggregation, deformation and structural changes of PPO from apple juice. Available findings provided in this study will benefit the food industry. • Critical and supercritical states of CO 2 strongly inhibited the PPO activity, thus stabilizing the quality of apple juice. • HP-CO 2 processing caused dissociation, conformation and aggregation of PPO. • Structural modifications in relation to activation and inactivation of PPO were studied. [ABSTRACT FROM AUTHOR]

Changes of microbial, physicochemical and sensory properties of mulberry juice processed by high hydrostatic pressure (HHP) (500 MPa/5 min), high-pressure carbon dioxide (HPCD) (15 MPa/55 °C/10 min), and high-temperature short time (HTST) (110 °C/8.6 s) during 28 days of storage at 4 °C and 25 °C were investigated. Total aerobic bacteria (TAB) and yeast and mold (Y&M) were not detected in HHP-treated and HTST-treated mulberry juices for 28 days at 4 °C and 25 °C, but were detected more than 2 log CFU/ml in HPCD-treated mulberry juice for 21 days at 4 °C and 14 days at 25 °C, respectively. Total anthocyanins were retained after HHP and reduced by 4 % after HTST while increased by 11 % after HPCD. Total phenols were retained by HHP, while increased by 4 % after HTST and 16 % after HPCD. The antioxidant capacity was retained by HTST and HHP and increased by HPCD. Both total phenols and antioxidant capacity were decreased during the initial 14 days but then increased up to 28 days regardless of storage temperature. The value of polymeric color and browning index decreased and a* increased in HHP-treated and HPCD-treated mulberry juices, while HTST-treated mulberry juice had a reverse result. The viscosity of mulberry juice increased in HHP-treated and HPCD-treated juices, while decreased in HTST-treated juice. During storage, total anthocyanins, total phenols, and antioxidant capacity and color in all mulberry juices decreased more largely at 25 °C than that at 4 °C. Better quality was observed in HHP- and HPCD-treated mulberry juices, and a longer shelf life was observed in HHP-treated samples compared to HPCD-treated ones. [ABSTRACT FROM AUTHOR]

Abstract: The individual and combined effects of high-pressure carbon dioxide (HPCD), mild heat (MH) and nisin (200 ppm) on the inactivation of natural microorganisms, including aerobic bacteria (AB), yeasts and molds (Y&M), in litchi juice were evaluated. The samples were treated at a pressure of 10 MPa and temperatures of 32, 42 or 52 °C for 5, 10, 15, 20, 25 or 30 min. Temperature played a prominent role in the inactivation of both AB and Y&M when combined with HPCD, particularly for AB at 52 °C and Y&M at temperatures ≥42 °C. Nisin increased the susceptibility of AB to the combined treatment of HPCD and MH (HPCD + MH). A reduction of 4.19 log cycles was achieved by HPCD + MH at 52 °C for 15 min, and complete inactivation of AB was obtained by combination of HPCD, MH and nisin (HPCD + MH + nisin). No significant effect of nisin was found on the inactivation of Y&M. [Copyright &y& Elsevier]

In this paper, we described the use of high-pressure carbon dioxide (HPCD) for the inactivation of natural microbes in lychee juice and evaluated its effects on lychee juice quality, compared to a conventional high-temperature, short-time (HTST) method. The HPCD treatments were carried out using a HPCD unit (8 MPa, 36 °C, 2 min), and the HTST was performed at 90 °C for 60 s. The results showed that five log reduction for yeasts and molds and total aerobic microorganisms occurred at 8 MPa for 2 min. And effects of the treatments on pH and concentrations of microbes, organic acids, titratable acidity (TA), total soluble solid (TSS), sugars, polyphenols, color, and free amino acids were also investigated. HPCD could efficiently maintain the concentration of polyphenols and original color at 8 MPa, 36 °C for 2 min. Insignificant differences in colors were observed between unprocessed and HPCD juices, while significant differences were observed between unprocessed and HTST juices. Furthermore, HTST decreased the total free amino acids, whereas HPCD caused a significant increase (increased by 45.92% at 8 MPa) ( p < 0.05). The increase in total amino acids induced by HPCD treatment is beneficial for nutritional value of commercial ready-to-drink lychee juice. In general, HPCD treatment had less influence on the measured quality parameters of lychee juice than HTST treatment. Therefore, HPCD treatment could be a useful alternative to traditional heat treatment. [ABSTRACT FROM AUTHOR]

Isobaric and isothermal semi-logarithmic survival curves of natural microflora in apple juice treated with high-pressure carbon dioxide at 7, 13, and 16 MPa pressures and 35, 50, and 60 °C temperatures were fitted with a nonlinear equation to find the values of the coefficient b( P ), b( T ), n( P ), and n( T ). Profiles of the model parameters were obtained as a function of pressure and temperature. The model fitted with good agreement ( R2 > 0.945), the survival curves. An empirical equation was proposed to describe the combined effects of pressure and temperature. The equation, derived from a power law model, was written in the form: . The proposed model fitted the experimental data well. At 7 MPa and 50 and 60 °C, 13 MPa and 35 and 60 °C, 16 MPa and 35 °C, the model provided log10 reduction residual values (observed value – fitted value) lower than 0.284 showing a good agreement between the experimental and the predicted survival levels. [ABSTRACT FROM AUTHOR]