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I. ANTONOVA, P. Mallikarjunan, and C. G. Haugh. Biological Systems Engineering, Virginia Polytechnic Institute and State University, 312 Seitz Hall, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061

Crispness is a very important and desirable textural characteristic that indicates freshness and high quality in fried foods. It can be determined by the combination of mechanical and acoustical properties; however, there is no objective method available for fried foods with a high-moisture core. Development of a technique that can be correlated with sensory crispness will provide new opportunities to develop products with desirable attributes.

The objective is to analyze the ultrasonic parameters in breaded fried foods using an ultrasonic evaluation system.

The battered and breaded chicken nuggets obtained from local fast-food restaurants were finish cooked in a restaurant-type fryer, convection oven, and microwave oven. The fried samples were placed uncovered under the heat lamp (60°C) to maintain crispness and also in high-humidity ambient conditions (60-80%). Crust thickness, moisture and fat content, and ultrasonic measurements were recorded. Dry-contact ultrasonic transducers in the through transmission mode at the frequencies of 50, 250, and 500 kHz were used.

This study found that ultrasonic parameters such as maximum amplitude and time-of-flight of the signal varied with the changes in sample properties. The maximum amplitude for the cooked chicken nugget was in the range of 0.4-1.8 V. The time-of-flight varied from 1.1 to 3.5 microseconds. Maximum amplitude increased with increase in the holding time, and amplitude through the sample under the heat lamp was found to be higher than amplitude through the sample held without the heat lamp.

Ultrasonic techniques can be successfully used in the food industry and provide significant advantages. Development of the method available to evaluate crispness in fried foods will allow such food industries as restaurants and foodservice institutes to produce foods with desired attributes and to serve their customers more rapidly.