| Abstract | Zrno kukuruza je izvor α-, γ- i δ-tokoferola te γ-tokotrienola, no, skladištenje i obrada zrna može smanjiti njihov sadržaj. Kada se zrno kukuruza zbog vremenskih neprilika ili nedostataka mehanizacije ne može ubrati u optimalno vrijeme, ono postaje manje vlažno te mu se mora rehidrirati radi uspješnog siliranja. Siliranje rehidriranog zrna stvara kiseli medij koji utječe na sadržaj bioaktivnih spojeva kao što su tokoli. Cilj ovog rada bio je utvrditi promjene u sadržaju tokola tijekom šesto-mjesečnog skladištenja silaže rehidriranog zrna kukuruza. Zrno sedam hibrida kukuruza (Bc 344, Bc 418b, Bc 424, Bc 525, Bc 572, Kekec i Pajdaš) ubrano je nakon fiziološke zrelosti te rehidrirano do 32% vlage i silirano uz dodatak komercijalnog inokulanta u vakuum vrećicama na sobnoj temperaturi. Vrećice su uzorkovane 0., 21., 38., 63., 100. i 185. dan. Tokoli su u svim uzorcima ekstrahirani heksanom nakon saponifikacije i kvantificirani HPLC metodom. Na temelju sadržaja tokola u svakoj vremenskoj točki skladištenja praćena je dinamika razgradnje tokola u kiselim uvjetima. Hibrid, vrijeme i način skladištenja su značajno utjecali na sadržaj tokola (P<0,001) pri čemu je tijekom skladištenja pao sadržaj tokola i u suhom i u siliranom rehidriranom zrnu, a silaže su imale niži sadržaj od suhog zrna istog hibrida. Hibrid Kekec je imao najveću brzinu razgradnje tokola dok je hibrid najmanje brzine razgradnje bio Bc 525. Najveći pad sadržaja ukupnih tokola utvrđen je u razdoblju do 21. dana skladištenja, blaži pad do 38. dana, a od 38. do 185. dana je došlo do stagnacije sadržaja u siliranom rehidriranom zrnu, dok je kod suhog zrna utvrđen značajan pad sadržaja u razdoblju od 100. do 185 dana. |
| Abstract (english) | Maize grain is the source of α-, γ- and δ-tocopherols and γ-tocotrienols, but storing and processing can reduce their content. When grains cannot be harvested at the optimal period due to adverse weather conditions or lack of mechanization, it does not contain sufficient moisture and needs to rehydrate for successful ensilaging. Ensilaging of rehydrated grain creates an acidic medium that influences the content of bioactive compounds such as tocols. The aim of this research was to determine changes in the content of tocols during six-month storage of rehydrated corn silage. Grain of seven maize hybrids (Bc 344, Bc 418b, Bc 424, Bc 525, Bc 572, Kekec and Pajdaš) was harvested after physiological maturity, rehydrated to 32% of moisture and ensiled with the addition of commercial inoculant in a vacuum bags at room temperature. The bags were sampled on days 0, 21, 38, 63, 100 and 185 of the experiment. Tocols were extracted with hexane after saponification in all samples and quantified by HPLC method. Based on the content of tocols at each storage time point, the dynamics of tocols degradation in acidic conditions was monitored. Hybrid, time, and type of storage had a significant effect on the contents of tocols (P<0.001), resulting in reduced tocol content during the storage period, in both dry and ensiled rehydrated grain, and lower content in silages than in dry grain of the same hybrid. Hybrid Kekec had the highest rate of degradation of the tocols, while the hybrid with lowest rate of degradation rate was Bc 525. The largest reduction in content of total tocols was in the period until 21st day of storage, milder reduction occurred until 38th day, and from 38th to 185th day, tocols content stagnated in ensiled rehydrated grain, while in dry grain, a significant reduction occurred in the period of 100th to 185th day. |
