Using Confocal Microscopy to Estimate the Distribution of Natural Antioxidants in Poultry Meal and Extruded Kibbles

Abstract

With the increasing demand for natural ingredients from the pet food market, new sources of natural antioxidants have been identified. However, many of them have low solubility in the traditional oil‐based delivery systems. To improve their distribution in dry matrices, new carriers and processes have been developed. To evaluate the effect of new delivery systems, a confocal microscopy method is developed. Based on confocal images, an emulsion carrier improves the distribution of hydrophilic antioxidants in poultry meal. Shelf life study shows that it slows down the decomposition of some lipophilic antioxidants even though it does not improve the oxidative stability of poultry meal directly. In extruded kibbles, confocal images show that hydrophilic compounds distribute better when added into premix before extrusion, while lipophilic compounds distribute well no matter when they are added. Confocal microscopy is a great tool for evaluating the effect of new delivery systems on antioxidants’ distribution. The overall performance of the antioxidant needs to be further evaluated through a comprehensive oxidative stability study.Practical Applications: Results presented in this paper may help renderers and pet food scientists to understand the distribution, migration, and performance of natural antioxidants in poultry meal and extruded kibbles. The confocal microscopy method developed in this study can be used to evaluate other delivery systems and in other protein‐rich dry matrices. Even though the water‐in‐oil emulsion improves the distribution of hydrophilic antioxidants and keeps the good distribution of lipophilic antioxidants, antioxidants in oil carrier still has the best performance in poultry meal. This reminds us of the importance of comprehensive oxidative stability studies in evaluating antioxidants performance.Two proprietary carriers’ effect on antioxidants’ performance in poultry meal through confocal imaging and shelf life study are evaluated. The confocal imaging method has been also tentatively used to estimate the distribution of antioxidants when added before and after extrusion in kibbles.