An electronic nose based on piezoelectric quartz crystal was developed for monitoring the maturation of carabao mango. This device detects the volatile organic compounds present in the headspace of the mango fruit. Nitrogen gas was used to transport at controlled flow rate the vapor compounds to a chamber that contains the piezoelectric quartz crystals. The crystals were coated with different organic polymers that interact by self assembled instrumentation and recorded by the computer in terms of frequency change. Chemical analysis was also done on the sample for its total sugar content using Clegg-anthrone method. The pH of the sample was also recorded.

The quartz sensors gave stable response to the mango fruit sample (response time 17 to 43 minutes), exhibited good repeatability (R.S.D = 3.3% to 5.1%; n=3) and good reproducibility (R.S.D. 1.9% to 6.1%; n = 5). Different signals were observed at different stages of the maturation of carabao mango fruit. As the fruit matures, the total sugar available increase as the pH also increases.

Principal component analysis (PCA) was done to discriminate the response of the electronic nose to different stages of maturation of mango. The assembled electronic nose could support, if not replace the sensory evaluation and chemical analysis wherein both of which requires trained personnel.

Keywords: Electronic nose; Piezoelectric quartz crystal; Mango fruit maturity; Principal component analysis

Thesis (Master of Science - Chemistry)

Includes appendices and bibliographical references