MEASUREMENT OF YOUNG COCONUT (COCOS-NUCIFERA, L) MATURITY BY SOUND-WAVES

Sounds produced by tapping fresh young coconut fruits of 'buko' have b een used by farmers/traders in the Philippines to differentiate their maturitY levels. Considering the importance of identifying the three s tages Of 'buko' maturity ('malauhog' 'U'; 'malakanin' 'K' and 'malakat ad' 'T') a scientific basis for measurement of sounds produced by tapp ing of 'buko' was studied Some physicochemical characteristics of 'buk o' were analyzed to determine if sound waves could be associated with them. 'Buko' was also stored at ambient temperature for 12 days and ch anges in tapping sounds during this period were followed. Results show ed that tapping sounds recorded on tapes (analog) can be converted to digital through the use of the analog-to-digital converter (ADC). Usin g the Fast Fourier Transformation the spectral magnitude of sound wave s was computed and graphically presented in a coordinate system where frequency was the abscisa. The Spectral magnitude of 'U' was found to be different from those of 'K' and 'T'. The former produced what was d escribed as a 'solid' sound while 'K' and 'T', gave 'hollow' sounds. A mong the physical characteristics measured, only thickness of coconut meat (fruit endosperm) significantly identified 'U' from 'K' and 'K' f rom 'T'. Chemical components of 'buko' meat such as crude fat and star ch tended to increase with increasing maturity level while moisture co ntent decreased significantly. Neither soluble solids or pH was signif icantly different between 'U', 'K' and 'T' But on storage, soluble sol ids decreased after the sixth day. The average of normalized magnitude spectrum for each of the maturity levels was computed to obtain the ' average power' There was a tendency for 'U' to have the lowest 'averag e power' compared to 'K' and 'T'. For all maturity levels, 'average po wer' tended to rise with increased storage time.