Utilization of industrial enzymes in the evaluation of neutral detergent insoluble fiber content in high-starch samples

Abstract Text: The method of analysis of fibrous components called "detergent system" was initially developed to evaluate forage and subsequently extended to other types of feeds. However, its application to analizing non-fibrous feeds is associated with some analytical problems, noticiably with high starch feeds. The use of a α-amylase is recomemended by AOAC International as a standard procedure to promote solubilization of the starch in feeds samples to obtain insoluble fiber with accuracy. Diferent amylases are available for industrial activities, which have, in general, certificated quality and activity. However, the type and amount of industrial enzymes that could potentially be used in evaluating the insoluble fiber have not established. It were performed two experiments to evaluate the utilization of industrial enzymes in the evaluation of neutral detergent fiber (NDF) contents in high-starch materials. In the first experiment, it was verified the accuracy of estimates of NDF obtained with the utilization of three industrial enzymes (Termamyl 2X, Liquozyme Supra 2.2.X, and Amylase AG 300L - Novozymes®) at different volumes (50, 100, 250 or 500 µL/sample). Samples were simulated to contain starch at 0, 100, 300, 500 and 1000 g/kg using purified cellulose and starch (n = 240). Estimates of the bias of NDF contents were evaluated by analysis of variance, acording in a completely randomized design in a 3 × 4 × 5 (three types and four volumes of enzymes and five concentrations of starch). In the second experiment, samples of corn grain and sorghum grain were evaluated considering the same enzyme types and volumes used in the first experimente, also incluiding aliquots without using enzyme addition (n = 104). There was no significant bias of NDF recovery for simulated samples containing starch up to 300 g/kg (P > 0.01). Considering those samples, none difference among enzymes was observed (P > 0.01). The results obtained from the evaluation of corn and sorghum suggest the use of 250 µl volume and enzyme necessary for the extraction of starch. Therefore, it can be recommended the utilization of 250 µL the α-amylases evaluated.

Keywords: α-amilase; feed analysis; fiber