2880 Research Article Received: 12 August 2014 Revised: 31 October 2014 Accepted article published: 27 November 2014 Published online in Wiley Online Library: 30 December 2014 (wileyonlinelibrary.com) DOI 10.1002/jsfa.7029 Maintaining functional properties of shell eggs by ultrasound treatment Cengiz Caner * and Muhammed Yuceer * Abstract BACKROUND: Ultrasonic treatment is an emerging technique that could be an alternative to existing thermal processing techniques in foods. Ultrasonic treatments may also be used to extend the shelf life of egg during storage period in ambient temperature. The effectiveness of ultrasound treatment with different power levels (200 W, 300 W, 450 W) and treatment times (2 min and 5 min) was evaluated for enhancing the functional properties of eggs during storage at 24 ∘ C for 6 weeks. RESULTS: Ultrasound treatment power and treatment time had significant effects on Haugh unit, yolk index, albumen pH, dry matter, relative whipping capacity, and albumen viscosity resulting in extended shelf life. Attributes such as yolk index, Haugh unit, pH, whipping capacity, dry matter for 300 W and 450 W treatments were better than control and 200 W treatments. Longer treatment time and power showed a significant influence on functional properties. CONCLUSION: Power levels of 300 W and 450 W of ultrasound treatments had improved internal quality of fresh eggs during storage, but negative effect on shell strength. The study showed that ultrasound treatment could be an alternative and effective technique for maintaining the internal qualities of fresh eggs during long-term storage while Fourier transform near infrared spectroscopy could be used as a new tool for the assessment of freshness. © 2014 Society of Chemical Industry Keywords: ultrasound; shell eggs; egg quality; shelf life; functional properties INTRODUCTION Fresh eggs are a natural and inexpensive source of high-quality protein in the human diet. Eggs are also one of the most con- sumed foods worldwide due to their multi-functional properties. 1 In 2011, around 70 million tons of egg were produced around the world. 2 Shell eggs undergo considerable quality changes result- ing in losses during storage due to the fact that eggs are highly perishable. Thus, it is necessary for eggs to reach the final con- sumer market without a considerable time lapse 3,4 or, if a time lapse is unavoidable, it is important to improve the egg fresh- ness and extend the shelf life using effective treatment techniques during storage and beyond. Development of non-thermal food preservation methods is necessary for maintaining the qualities of perishable foods. Non-thermal methods allow processing of foods below the temperatures used during thermal pasteurisation. Several non-thermal technologies, including high hydrostatic pressure, 5 – 7 ultrasound, 8,9 pulsed electric fields, 10 – 13 and ozonation 14 – 17 have been developed and studied in recent years for perishable food. Ultrasonic treatment is one of these emerging techniques that could be the alternative to existing thermal processing tech- niques. It is based on the transmission of ultrasonic sound waves (20–100 kHz frequency) through a medium. It enhances con- vective heat transfer as well as generates bubble explosions, which produce local hot spots that could cause inactivation of microorganisms and destruction of enzymes by cavitation. 18,19 High-power ultrasonic treatment is also known to damage or disrupt biological cell walls, which will result in the destruction of living cells. 9,19 – 21 The use of ultrasound in fresh produce as a non-thermal technique is a relatively recent endeavour and considered as a food preservation method to enhance food qual- ity, safety and stability. Recently, numerous ultrasound studies have been published on fruits, vegetables, fruit juices and dairy products. 9,19,22 Similarly, using ultrasonic waves may improve the overall characteristics of shell eggs that will result in significant savings for the egg industry. A considerable amount of published work on ultrasonic treat- ment has dealt with microbiological effects on perishable food rather than functional and chemical properties even though it has a broad range of use in food industry. 19,22 – 29 Thus, it is necessary to investigate the use of ultrasound in the protection of the inter- nal qualities of shell eggs. To the best of the authors’ knowledge, no other studies have been conducted or published to determine the effects of ultrasound on functional properties of shell eggs. For this reason, the objectives of this work were to investigate the effects of different ultrasound power and treatment times on inte- rior qualities of shell eggs including functional properties [relative whipping capacity (RWC), Haugh units (HU), viscosity and pH of ∗ Correspondence to: Cengiz Caner and Muhammed Yuceer, Canakkale Onsekiz Mart University, Engineering Faculty, Department of Food Engi- neering, 017020-Canakkale, Turkey. E-mail: ccaner@comu.edu.tr; myuceer@ comu.edu.tr Department of Food Engineering, Canakkale Onsekiz Mart University, 017020, Canakkale, Turkey J Sci Food Agric 2015; 95: 2880–2891 www.soci.org © 2014 Society of Chemical Industry