Combined effects of pulsed electric field and ultrasound on bioactive compounds and microbial quality of grapefruit juice

Abstract

The combined effect of ultrasound (US) and pulsed electric field (PEF) was investigated on microbial load and bioactive compounds of grapefruit juice. Grapefruit juice was PEF treated (flow rate: 80 ml/min, pulse frequency: 1 kHz, 20 kVcm−1 electric field strength, temperature: 40 °C, time: 600 μs) followed by US treatment in an ultrasonic bath cleaner radiating 600 W at frequency of 28 KHz and 20 °C for 30 min. PEF and US treatment resulted in a significant reduction in microbial load as compared to the control group. Using combined (PEF + US) treatment, carotenoids, lycopene, anthocyanin contents, and total antioxidant activity were increased from 0.84 μg/ml, 0.32 μg/ml, 1.37 mg/L, and 177.48 ascorbic acid equivalent µg/g (control) to 1.26 μg/ml, 0.92 μg/ml, 1.68 mg/L, and 262.32 ascorbic acid equivalent µg/g, respectively. The findings demonstrated that PEF + US could be successfully used for preserving bioactive compounds in grapefruit juice while improving the microbial quality for a better shelf‐life. Practical applications In recent years, nonthermal techniques, such as sonication and PEF or combination of these are used for the inactivation of microorganism and preserving the bioactive compounds of different juices. The results of the present study revealed that combined treatment (PEF + US) could improve the antioxidant activity, total phenolics, flavonols, flavonoids, lycopene, and total carotenoids. The findings of this study suggested that PEF + US has a potential to improve the quality of grapefruit juice and may be employed for the processing of grapefruit juice at industrial scale.

Application of ultrasound and high‐pressure homogenization against high temperature‐short time in peach juice

“…Zafra‐Rojas et al () also stated that sonicated samples with the help of amplitude and time during treatment caused the higher antioxidant activity. The results of present work are in a good agreement with the results of Aadil et al () who announced improved antioxidant activity in US‐ and pulsed electric field (PEF)‐treated grapefruit juice might be due to the inactivation of oxidative enzymes and the release of phenolics from cell structure.…”

Comparison of chemical, physical, and ultrasound treatments on the shelf life of fresh‐cut quince fruit ( Cydonia oblonga Mill.)

“…A comparable result was also observed in the work of Bhat, Kamaruddin, Min‐Tze, and Karim () and higher TPC of lime samples following the US application, also an increase in TPC in sonicated pear samples was also pointed out (Cruz‐Cansino et al, ). This change might be correlated with the release of the bound form of phenolic content because of the deformation of the cell wall by the cavitation phenomena (Aadil, Wang, et al, , ).…”

Effects of high‐power ultrasound on microflora, enzymes and some quality attributes of a strawberry drink

“…Besides, there may be some microbes with high resistance to HPU present in the strawberry drink. To achieve a better pasteurization effect for purposes of food preservation, HPU may be used in combination with other non‐thermal methods such as high hydrostatic pressure (HHP) pulsed electric field (PEF) or high‐pressure carbon dioxide (HPCD)…”