Influence of chemical inhibitors on fermentation process and hygienic quality of high moisture corn

Abstract

The aim of work was to find influence of chemical inhibitors on fermentation process and hygienic quality of high moisture corn. In experiment was used high moisture maize corn with content of dry matter from 602.0 to 613.3 g. After harvest was corn directly mechanically processed on crusher. Three different variants of high moisture corn were examined: K – untreated control, A – treated with a chemical inhibitor containing propionic acid and formic acid in application dose 3.5 kg per ton of maize corn, B – treated with a chemical inhibitor containing propionic acid, formic acid, benzoic acid and calcium formiate in application dose 3.4 kg per ton of maize corn. The maize corn was filled into plastic bins and placed in laboratory of conservation at 18-22o C. After four months were plastic bins opened and the average samples were determined for content of nutrients, parameters of fermentation process and content of microscopic fungi. For determination of colony-forming units (cfu) 20 g samples of ground corn were soaked in 180 ml sterile tap-water containing 0.02 % Tween 80 and then 30 min. homogenized. Dilutions (from 10-1 to 10-4) in sterile tap-water with 0,02 % Tween 80 were prepared and 1 ml aliquots were incubated on three plates of Malt agar and CzapekDox agar with streptomycin (to inhibit the bacterial growth) and Petri dishes were inoculated using the spread-plate technique and incubated at 25 °C. Total cfu.g-1 counts of samples were determined after 5-7 days of incubation. For isolation and identification of genera of fungi Czapek-Dox agar and malt agar tender the same incubation conditions as cfu were used. Taxonomic identification of all colonies of isolated fungi was made according to Klich (2002), Samson et al. (2002), Hoog et al. (2000). Moulds and mycotoxins are common contaminants of forage crops and silages made from them in many areas of the world. They pose a potential health hazard to domestic livestock. Changes in environmental conditions from pre-ensiling through fermentation result in the establishment of a characteristic mycoflora, mainly represented by Penicillium, Aspergillus and Monascus species. In addition to field-derived mycotoxins, the proliferation of these filamentous fungi upon subsequent exposure to air during feedout can result in further increase in the mycotoxin load of silages. Good management of the growing crop, the ensiling process and the unloading phase must be employed to minimize moulds and mycotoxins. In our experiment addition of chemical inhibitors in conservation of high moisture corn did not affect occurrence of species and genus, but inhibited number of the microscopic fungi. From results follows that the highest value of pH had maize corn with addition of inhibitor containing organic acids and salts of acids in the cause the lowest content of lactic acid. High moisture corn with chemical additives had lower total content of fermentation acids. Addition of chemical inhibitors decreased content of lactic acid, acetic acid and did not affect content of butyric acid. After application of chemical additive consisting of organic acids had high moisture corn the lowest value of pH. Treatment of maize corn with chemical inhibitor composed of propionic and formic acid influenced hygienic quality and fermentation process expressively.