USE OF ELECTRONIC NOSE TO DETECT ...

USE OF ELECTRONIC NOSE TO DETECT CHANGES IN PASTEURIZED CUPUAÇU (THEOBROMA GRANDIFLORUM) PULP AROMA F.M. SILVA, D.A. Luzuriaga, M.O. Balaban & C.L.M. Silva Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino Almeida, 4200 Porto, Portugal. JUSTIFICATION Cupuaçu is a tropical Brazilian fruit with a unique aroma. The pulp is used in making beverages and added to dairy products. The method used for preserving the pulp is thermal pasteurization. However, this process causes changes in the original aroma. The electronic nose, in combination with sensory tests, can quantify these changes. This is a rapid, easy and repeatable method. OBJECTIVES - To pasteurize cupuaçu pulp using different time-temperature combinations, - To measure the resulting aroma changes using an electronic nose, - To evaluate the discrimination capability of the Multiple Discriminant Analysis Method regarding the above data. METHODS Isothermal experiments were conducted in Ziploc bags at four temperatures (70, 80, 90, and 98ºC) for five different pasteurization times depending on temperature, and then cooled in ice slush. Two replicate runs were made at about one month interval. The samples were then analyzed using a Neotronics 4000 Electronic Nose. Data was analyzed using ANOVA and Multiple Discriminant Analysis with the software Statistica. RESULTS The electronic nose sensors could detect both the effects of pasteurization times and temperatures on the cupuaçu pulp aroma (ANOVA analysis). Multiple Discriminant Analysis plots revealed that the electronic nose could clearly discriminate between cooking temperatures, and between cooking times at each temperature. It was also shown that samples held in frozen storage for up to a month were slightly different in odor as determined by the electronic nose. SIGNIFICANCE It was apparent that the electronic nose can discriminate between samples treated at different temperatures and for different time periods. This, combined with evaluation of the samples by sensory panels, will enable rapid determination of the “smell quality” of a pasteurized cupuaçu sample, and the optimization of the pasteurization parameters using smell criteria.