167 Agriculturae Conspectus Scientiicus . Vol. 81 (2016) No. 3 (167-171) ORIGINAL SCIENTIFIC PAPER Summary A comparative study regarding standard fruit quality measurements (fruit mass, irmness, soluble solids concentration, starch conversion rate and Streif index) and acoustic properties (resonant frequency, peak width, resonant frequency/peak width ratio and stifness) were conducted in ‘Gloster’ apples during two seasons. he indings obtained indicate no signiicant diferences between seasons in studied quality parameters as well as in acoustic properties. he fruits were characterized with unusual high mass and high variation in resonant frequency and peak width, especially in season-I. In about 50% of examined fruit, the acoustic signal was not typical with one clearly visible peak, and appeared with two or, in few cases, even three peaks that were sometimes of similar height. he fruit mass was negatively correlated with resonant frequency, but correlation coeicient was lower in season-I and less signiicant than in season-II. Correlation coeicient between fruit mass and peak width was the same in both seasons. Although positive correlation existed between fruit mass and resonant frequency/peak ratio in both seasons, correlation coeicient in season-I was higher and more signiicant than in season-II. Correlation between fruit mass and stifness existed only in season-II. Resonant frequency was positively correlated with peak width only in season-I. Stifness was positively correlated with Streif index and peak width only in season-II. hough not signiicant, higher variations in acoustic properties than standard quality measurements still indicate some usefulness of acoustic impulse method for determination of fruit quality of ‘Gloster’ apple. However, further research is needed to elucidate the signiicance of individual acoustic parameters and their relation to fruit quality. Key words acoustic properties, apple, irmness, fruit quality, non-destructive measurements, stifness Analysis of Acoustic Impulse Method for Determining Firmness and other Quality Parameters of ‘Gloster’ Apple Tomislav JEMRIĆ 1( ) , Josip BUHIN 1 , Mladen FRUK 1 , Luka GAŠPAR 2 , Anita MRČELA 1 , Tihana VAŽIĆ 1 , Mushtaque A. JATOI 1,3 , Marko VUKOVIĆ 1 1 University of Zagreb, Faculty of Agriculture, Department of Pomology, Svetošimunska cesta 25, 10000 Zagreb, Croatia e-mail: tjemric@agr.hr 2 Fragaria d.o.o., Trnošćica bb, 10370 Dugo Selo, Croatia 3 Shah Abdul Latif University, Date Palm Research Institute, 66020, Khairpur, Pakistan Received: February 22, 2017 | Accepted: March 22, 2017