Optimization of ohmic heating parameters for polyphenoloxidase inactivation in not-from-concentrate elstar apple juice using RSM
In this study, optimization of ohmic heating (OH) process parameters (temperature and voltage gradient) to inactivate polyphenoloxidase (PPO) of not-from-concentrate (NFC) apple juice was conducted. Response surface methodology was used for optimization of OH parameters, where the voltage gradient and temperature on the PPO activity in the NFC apple juice was evaluated. Then the optimized condition was used to produce the NFC apple juice and the quality parameters were evaluated and compared to NFC apple juice prepared by conventional heating (CH). The studied parameters were: PPO activity, total phenolic, total carotenoids, ascorbic acid, cloud value, color as well as physical properties (i.e., TSS, acidity, electric conductivity and viscosity). The reduction of PPO activities was 97 and 91% for OH (at 40 V/cm and 80 °C) and CH (at 90 °C and 60 s), respectively. The reduction of the ascorbic acid was 66.8% for OH significantly lower than the 80% for CH treated samples. The total extracted phenolic content was increased by 5.4 and 2.5% with OH and CH treatments, respectively. The decrease in the concentration of total carotenoids for OH (13.17%) was significantly lower than for CH (34.23%). The color values (L*, a*, b* and ΔE) were only significantly increased in the OH treatment. OH is a potential mild thermal treatment in the production of apple juice with improved functional properties instead of conventional methods.
KeywordsOptimization Apple juice Ohmic heating Polyphenoloxidase Carotenoids Ascorbic acid
Response surface methodology design
Tarek G. Abedelmaksoud would like to thank The Danish Agency for Higher Education for a research grant for his stay as a guest Ph.D. student for one year at Food Production Engineering Research Group, Technical University of Denmark.
Compliance with ethical standards
Conflict of interest
The authors have no competing interests.
- Clark JP (2009) Case studies in food engineering. Chapter 6: fruit and vegetable juice processing. Case studies in food engineering. Food engineering series, p 224Google Scholar
- Demirdöven A, Baysal T (2009) Ohmic heating applications on fruit and vegetable products. In: International conference on bio and food electrotechnologies, 22–23 October 2009, Compiègne, France, pp 294–300Google Scholar
- Helrich K (1990) Official methods of analysis of the association of official analytical chemists, vol 2, 15th edn. The Association of Official Analytical Chemists, ArlingtonGoogle Scholar
- Lima M (2007) Ohmic heating: Quality improvements. Encyclopedia of Agricultural, Food, and Biological Engineering 1:1–3. https://doi.org/10.1111/j.1745-4549.1999.tb00395.x
- Makroo HA, Saxena J, Rastogi NK, Srivastava B (2016) Ohmic heating assisted polyphenol oxidase inactivation of watermelon juice: effects of the treatment on pH, lycopene, total phenolic content, and color of the juice. J Food Process Preserv. https://doi.org/10.1111/jfpp.13271 CrossRefGoogle Scholar
- Myers RH, Montgomery DC (1995) Response surface methodology, process and product optimization using designed experiments, 2nd edn. Wiley, New YorkGoogle Scholar
- Ramaswamy R, Balasubramanıam VM, Sastry SK (2005) Ohmic heating of foods-fact sheet for food processors. Ohio State University (OSU). http://ohioline.osu.edu/fsefact/0004.html. Accessed 22 Apr 2009
- Redd JB, Hendrix CM, Hendrix DL (1986) Quality control manual for citrus processing plants, book 1. Intercity, Safety Harbor, FLGoogle Scholar
- Trejo-Gonzalezl A, Soto-Valdez H (1991) Partial characterization of polyphenoloxidase extracted from ‘Anna’ apple. J Am Soc Hortic Sci 4:672–675Google Scholar
- Versteeg C, Rombouts FM, Spaansen CH, Pilnik W (1980) Thermostability and orange juice cloud destabilizing properties of multiple pectinesterases from orange. J Food Sci 45:969–971. https://doi.org/10.1111/j.1365-2621.1980.tb07489.x CrossRefGoogle Scholar