Electrophoresis as a method for characterization of protein changes in maize after pelleting process

Abstract

One of the most important crops used in animal feeding is maize (Zea mays L). Kernels of maize contain 7-13 g of proteins/100 g of dry matter, and they are protagonists of chemical and physical changes during the processing of raw material. There are several methods for the determination of protein changes during thermal processing. The objective of this study was to investigate application of Lab-on-a-Chip electrophoresis as a method for qualitative and quantitative determination of maize protein modifications during pelleting. Parameters that were varied during the pelleting process were the diameter of sieve openings of the hammer mill and the duration of steam conditioning process. According to the results, conditioning retention time of 5 min could be considered as mild in terms of protein changes for samples ground to pass 3 and 4 mm sieves. Conditioning retention time of 10 min was long enough for achieving a high level of protein modifications for all samples. Regression analysis of obtained data showed that both independent parameters had significant (p < 0.05) influence on the response variable (protein solubility). Protein electrophoregrams of investigated samples were qualitatively nearly identical, but quantitative differences occurred, especially in the range 18-85 kDa of protein molecular weight (MW). The results presented here show that Lab-on-a-Chip electrophoresis registered changes in protein structure even when protein solubility was not changed, unlike other conventional methods. This method can be used for the determination of the degree of protein changes during the pelleting process with remarkable certainty.