Abstract:

To evaluate the fresh-keeping effect of limonene as a natural preservative, the emulsification of limonene with various emulsifers and the changes in physicochemical and microbiological and sensory attributes of freshly squeezed sweet orange juice added with emulsified limonene during storage at (36 ± 1) ℃ were investigated. The attendance of sucrose ester SE-15 at the concentration of 20 g/L in the aqueous solution gave the best emulsification of limonene, with an absorbance difference at 420 nm of the emulsion before and after centrifugation. The addition of SE-15 emulsified limonene at the level of 0.25 g/L had no obvious fresh-keeping effect on sweet orange juice. However, the treated sweet orange juice exhibited a much lower total number of bacteria than the control without the addition of SE-15 emulsified limonene after 3 days of storage. There were no obvious differences in pH and sensory attributes between the treated and untreated sweet orange juices throughout the 8-day storage period. When the amount of added emulsified limonene was no less than 0.50 g/L, an obvious fresh-keeping effect on sweet orange juice was observed. Moreover, the treated sweet orange juice was better than the control in terms of total number of bacteria, pH and sensory attributes.

Key words: limonene, orange juice preservation, emulsification