Optimization of ohmicsonication for overall quality characteristics of NFC apple juice

In this work, the feasibility of using ohmicsonication (OS) as a new hurdle technology for pasteurization of not-from-concentrate (NFC) apple juice was proposed. Optimization of OS conditions (ohmic heating [OH] temperature and sonication time) was done by response surface methodology with polyphenoloxidase (PPO) activity as endpoint evaluation of the NFC apple juice.

The effect of OS as well as sonication (S), thermosonication, OH as an alternative to traditional technologies on inactivation of PPO and some quality parameters were studied. The obtained results showed that the highest inactivation of PPO was by OS treatment (98%). The highest bioactive profiles (ascorbic acid, total carotenoids, and total phenolic contents) and color values were obtained with the S and OS compared to other treatments.

In addition, the lowest hydroxymethylfurfural and cloud values were with OS. Finally, OS could be applied as an alternative thermal process to produce NFC apple juice. Practical applications: The results of this study showed that the lab scale ohmicsonication (OS) succeeded as an alternative thermal process to produce NFC apple juice.

OS process showed less degradation of the bioactive profile and improved inactivation of polyphenoloxidase in comparision to other treatments. Ohmic heating (OH) is already used in many factories. Therefore, we proposed to include an ultrasound probe instead of the existing blenders in the mixing tank before OH line.

This would improve the mixing process as well as getting the ultrasound benefits.