engleski

Carotenoid degradation during lactic fermentation of rehydrated maize grain from various hybrids

Lactic fermentation is commonly used in preservation of high-moisture feeds making them available for animal feeding throughout a year. Maize is often ensiled and even dry grain could be ensiled after rehydration. Maize grain is the only cereal with significant carotenoid content and this study aimed to examine the effect of ensiling on changes in carotenoid content in rehydrated grain compared to dry grain during prolonged storage. Grain of seven maize hybrids (Bc 344, Bc 418b, Bc 424, Bc 525, Bc 572, Kekec and Pajdaš) was harvested after physiological maturity. One part of grain was rehydrated to 32% of moisture and ensiled with the addition of commercial inoculant containing lactic acid bacteria in vacuum bags at room temperature (22-25 °C). The other part was stored in conventional silo where temperature was monitored daily. The ensiled rehydrated and dry grain were sampled on days 0, 21, 63, 100, 185, 310 and 420 of the experiment. Lutein, zeaxanthin, β-cryptoxanthin and β-carotene in all samples were quantified using reverse-phase HPLC method. Contents of determined carotenoids varied across tested hybrids (P<0.001), and their ranges (µg/g DM) at the beginning were 25.83-9.47 for lutein, 19.35-11.18 for zeaxanthin, 4.71-1.70 for β-cryptoxanthin and 2.06-0.56 for β-carotene. Carotenoid contents in all hybrids decreased both in dry and ensiled rehydrated grain (P<0.001) ; in comparison to the beginning, total carotenoid content was lower 30.10-43.61% in dry and 16.37-47.34% in ensiled rehydrated grain on 420th day of the experiment. However, the changes in dry and ensiled rehydrated grain throughout the experimental period differed. While carotenoid contents decreased linearly in dry grain (R2=0.98 for total carotenoids), in ensiled rehydrated grain, polynomial dependence was observed. Contents of all determined carotenoids in ensiled rehydrated grain of tested hybrids sharply decreased to 63rd day (up to 50%), then increased to 185th day (up to 39% compared to 63rd day) and then linearly decreased to the end of the experimental period. Although carotenoids degrade in acidic conditions during ensiling, results suggest that some carotenoids were captured in maize microstructure and released upon changes in microstructure during prolonged ensiling.

Carotenoids ; Maize ; Rehydrated grain ; Lactic fermentation

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