Solid-phase microextraction and gas chromatography-mass spectrometry of volatile compounds from avocado puree after microwave processing

Microwave processing offers an alternative to blanch fruits and vegetables, since the application of high temperature and short time often results in minimum damage. An experimental design was used to investigate the effect of microwave time, pH, and avocado leaves (independent variables) on avocado flavor (response) using solid-phase microextraction (SPME)-GC-MS. Among the fully characterized flavor volatiles, 19 compounds were derived from lipid oxidation and only 4 from the avocado leaves. The main components derived from lipids were aldehydes, ketones and alcohols. Terpenoids, estragole, and 2-hexenal [E] were volatiles derived from avocado leaves. When leaves were added to fresh and microwaved avocado terpenoids and 2-hexenal [E]/hexanal ratio increased, this behavior was considered to have a positive effect on the sensorial quality of the product. From the statistical analysis of the experimental design, it was possible to determinate that the most important factors influencing the abundance of flavor compounds derived from lipids were microwave time and pH. Maximum values of these compounds were detected at high levels of microwave time and low values of pH. On the other hand, response surface of terpenoids and estragole showed an increment when microwave time and avocado leaf was increased. The region of optimum response was 30s microwave time, pH 5.5, and 1% of avocado leaf.