Physical Properties of African Star Apple Fruits and Seeds

Abstract

This research examines the physical properties of African star apple (Chrysophyllum albidum) fruits and seeds. The dimensions were measured with vernier calliper and the dimensional properties were computed using appropriate equations. The densities, porosity, angle of repose and coefficient of friction on three material surfaces were determined with standard methods from literature. The result of the study showed that the average major, intermediate and minor dimensions were 47.95 mm, 43.70 mm and 41.35 mm respectively for the fruits, and 26.05 mm, 15.12 mm and 6.07 mm respectively for the seeds. The volume, shape index and one thousand weight of fruits were obtained as 40.61 mm3, 0.95 and 48.34 kg respectively whereas those of the seeds were obtained as 1.69 mm3, 0.95 and 1.28 kg respectively. The true density, bulk density and porosity of the fruits were found to be 1710 kg/m3, 1550 kg/m3 and 52.63 percent respectively, while that of the seeds were found to be 950 kg/m3, 570 kg/m3 and 40.25 percent respectively. The sphericity obtained for the fruits and seeds were 0.94 and 0.55, respectively. Angle of repose was found to be 3.02o and 13.50o for the fruits and seeds, respectively. Coefficients of friction on plywood, mild steel and galvanized steel were 0.30, 0.24 and 0.20 respectively, for the fruits and 0.52, 0.46 and 0.39 respectively for the seeds. The empirical data from this study will aid researchers in the design and development of postharvest systems for the African star apple fruits and seeds postharvest operations.

Ovo istraživanje prikazuje fizičke osobine plodova i semena jabuke Afrička zvezda (Chrisophillum albidum). Dimenzije su merene preciznim pomičnim merilom (nonijus-mikrometar). Karakteristične dimenzije izračunate pomoću odgovarajućih relacija i jednačina. Zapremina, poroznost, ugao nagiba i koeficijent trenja po podlozi za tri površine različitih materijala utvrđeni su standardnim metodama iz literature. Rezultat studije je pokazao da su prosečne velike, srednje i male dimenzije jabuke bile: 47,95 mm, 43,70 mm i 41,35 mm za plodove, odnosno 26,05 mm, 15,12 mm i 6,07 mm za seme jabuke. Gustina, indeks oblika i težina hiljadu plodova, dobijeni su kao 40,61 mm3, 0,95 i 48,34 kg, dok su semena dobijena kao 1,69 mm3, 0,95 i 1,28 kg, retrospektivno. Utvrđeno je da su stvarna gustina, zapreminska težina i poroznost plodova 1710 kg/m3, 1550 kg/m3, odnosno 52,63 %, dok je određeno da je gustina semena 950 kg/m3, 570 kg/m3 i 40,25 % retrospektivno. Dobijena sferičnost plodova i semena jabuke iznosila je 0,94, odnosno 0,55. Utvrđeno da je ugao mirovanja (nema kotrljanja) za plodove 3,02°, odnosno za seme 13,50°. Koeficijenti trenja po šper ploči, mekanom čeliku i pocinkovanom čeliku su vrednosti 0,30; 0,24, i 0,20 za plodove, odnosno 0,52; 0,46 i 0,39 za semena jabuke. Empirijski podaci iz ove studije pomoći će istraživačima u dizajnu i razvoju sistema čuvanja za plodove i semena jabuke Afrička zvezda (Chrisophillum albidum) posle berbe.