Changes in breaking force in relation to the number of impacts to witch the grain is exposed

Oštećenja zrna koja nastaju tijekom žetve i rukovanja predstavljaju izazov u posliježetvenoj tehnologiji žitarica. Cilj ovog diplomskog rada bio je utvrditi sile lomljenja kukuruznog zrna koje će biti izloženo različitom broju udaraca, od izostanka udaraca do raspona od 5 do 40 udaraca. Sile pri kojima su zrna bila polomljena određene su kod 5 razina vlage. Prosječna sila pri kojima su polomljena zrna kod najmanjih vlaga (od 11,71 do 11,83%) iznosila je 0,60 kN, a kod najvećih vlaga (od 25,43 do 26,98%) prosječna sila iznosila je 0,41 kN. Statistička analiza podataka je pokazala da postoji signifikantna razlika u prosječnim silama između razina vlaga. Kako se povećavala vlaga zrna tako se smanjivao broj polomljenih zrna. Kod vlaga zrna između 11,71% i 11,83%, broj nepolomljenih zrna kretao se od 21 do 38, dok je kod vlaga između 25,43% i 26,98%, broj nepolomljenih zrna bio u rasponu od 68 do 83. Ukupno je najviše polomljenih zrna u prosjeku utvrđeno u uzorcima koji su uzeti iz polja 2 (50,89%), a najmanje u uzorcima koji su uzeti iz polja 4 (64,89%). Dobiveni podaci mogu pomoći kod procjena koliko bi se moglo očekivati oštećenih zrna kod izvođenja određenih zahvata pri vlagama zrna koje su bile u istraživanju. U ovom istraživanju zrno je uvijek postavljano u položaj klica prema dolje i korišten je samo jedan hibrid. U sljedećim istraživanjima trebalo bi uključiti više hibrida koji su uzgojeni na različitim razinama dodanog dušika i koji se razlikuju u odnosu tvrdog i mekog endosperma te odrediti veličinu sila kada se zrno postavi u drugi položaj.Kernel damage that occurs during harvest and handling represents a challenge in post-harvest grain technology. The aim of this thesis was to determine the breaking forces of corn kernels that will be exposed to a different number of hits, from the absence of hits to a range of 5 to 40 hits. The forces at which the kernels were broken were determined at 5 moisture levels. The average force at which the grains were broken at the lowest moisture content (from 11.71 to 11.83%) was 0.60 kN, and at the highest moisture content (from 25.43 to 26.98%), the average force was 0.41 KN. Statistical analysis of the data showed that there is a significant difference in the average forces between the moisture levels. As the grain moisture level increased, the number of broken kernels decreased. With kernel moisture levels between 11.71% and 11.83%, the number of unbroken kernels ranged from 21 to 38, while at moisture levels between 25.43% and 26.98%, the number of unbroken kernels ranged from 68 to 83. In total, most of the broken kernels were found on average in samples taken from field 2 (50.89%), and the least in samples taken from field 4 (64.89%). The obtained data can help in estimating how many damaged kernels could be expected when performing certain operations at the moisture content of the kernels that were in the research. In this study, the grain was always placed in the germ-down position and only one hybrid was used. Further research should include more hybrids that are grown at different levels of added nitrogen and that differ in the ratio of hard and soft endosperm and determine the magnitude of the forces when the kernel is placed in a different position