Ácidos orgânicos visando melhoria da estabilidade de rações peletizadas com melaço externo

Abstract

The development of molds in food and the possibility of mycotoxins production by these fungi has become a public health problem. Restricting fungal contamination of food and feedstock is one of the most important steps to ensure food safety. A way to prevent the fungal growth is the use of organic acids. These compounds have antimicrobial activity, they reduce the food pH and the intracellular pH of the microorganism. The aim of this paper was to determine the Minimum Inhibitory Concentration (MIC) of the organic acids and its combinations against the aflatoxigenic Aspergillus flavus and therefore, evaluate the effect of the addition of organic acids combination on the stability of animal feed pelleting with external molasses. Organic acids and salt isolated: acetic acid (AA), lactic acid (LA), propionic acid (PA) and potassium sorbate (PS) and the combined ones (AA+PA, AA+PS, LA+PS, AA+LA, LA+PA and PA+PS) were tested in vitro for the inhibition of 104 spores. mL-1 of A. flavus NRRL 3251. Seven treatments, (T1: Acid Control, T2: Comercial PA, T3: PA1 0,025%, T4: PA2 0,1%, T5: PA+CA 0,025+0,25%, T6: PA+PS 0,025+0,25% and T7: PA+LA 0,1+0,4%) were applied in animal feed pelleting with external molasses and the stability of the animal feed was evaluated for a period of 60 days of storage. The analyses of yeasts and molds count, moisture, pH, water activity and acidity were performed after 1, 7, 14, 30, 45 and 60 days. Among the compounds evaluated individually, propionic acid (PA) was the most efficient in inhibiting A. flavus (MIC = 26,99 mM), followed by acetic acid (AA) (83,26 mM) and potassium sorbate (PS) (133,13 mM). Among the combinations, the best MIC results were AA (41,63 mM) + PA (3,37 mM), AA (4,16 mM) + PS (6,65 mM) and PA (3,37 mM) + PS (16,64 mM), showing the best performance of the compounds to inhibit A. flavus when they are combined. It was not possible to determine the stability of animal feed pelleting with external molasses, due to the low water activity of the sample and the storage conditions, being in lower levels than those that are required for the fungal growth deteriorating (Aw > 0,80). Intrinsic factors related to the product and the extrinsic factors related to the environment should be considered in order to evaluate the potential effectiveness of the organic acids as antifungals in stored animal feed, ensuring the safety and quality of the product until the moment of consumption.