Use of Electronic Nose Technology to Examine Apple Quality^*

Abstract

Apples, traditionally an ethnic food, have become a globally desired food commodity. According to Smock and Neubert (1950), “the original home of the apple (Malus sylvestris is not know but it is thought to be indigenous to the region south of the Caucasus, from the Persian province of Ghilan on the Caspian Sea to Trezbizond on the Black Sea.)” Apples have probably existed from prehistoric times in both the wild and cultivated states in Europe from the Caspian Sea to the Atlantic Ocean (Hulme and Rhodes, 1971). Apples were available as early as 100. B.C., but “Pearmian” appears to be the first variety recorded in history appearing in 1204 in a deed relating to the lordship of Runton in Norfolk. In America, there are records as early as 1647 of apples having been grafted on seedling rootstocks in Virginia. By 1773, three years before the American War for Independence, apples from America were found in the London markets. The spread of the cultivation of apples in the United States is ascribed to Johnny Appleseed (John Chapman) who established nurseries in Pennsylvania and Ohio.

Within the last 5 years there has been a major surge in the development of electronic nose technology (conducting polymers and metal oxide sensors). These multisensor electronic nose (E-nose) devices are coupled to statistical data processing packages designed to simulate the way the human brain interprets or processes the interaction of multiple sensory inputs. Fortunately, to be able to develop an electronic instrument that, in the broadest sense of the word, mimics the human olfactory system, it is not necessary to understand exactly how the human brain interprets complex vapors. E-nose technology has encouraged a wide dissemination of this instrumentation within the food and fragrance industries where it is now used primarily for quality control. Analysis time using an E-nose is often only a few minutes making it a viable alternative to longer classical gas chromatographic (GC) techniques.

The fruit component of fresh-cut produce is the fastest growing market in today’s produce business, representing a value-added, ready-to-use commodity that satisfies consumer requirements for authentic flavor, texture, nutritional value, and safety. These requirements challenge the packager/producer to develop cost effective ways of producing and monitoring their products for the presence of spoilage and/or pathogenic microflora and to stabilize and maintain their product’s flavor. Therefore, we developed an E-nose method to distinguish differences in and keeping-quality of whole, fresh-cut, and minimally processed Gala variety apple using a 32 sensor (AromaScan™ A32/50S multisampler).

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^*Mention of brand or firm names does not constitute an endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned.