Sedimentation field-flow fractionation: Size characterization of food materials

Sedimentation field-flow fractionation (SdFFF) was applied to characterize particle size distributions of food materials. Two types of food particles were examined, including milk suspensions and flour samples. Milk eluted in the normal mode SdFFF, whereas the steric mode of retention was used for flour samples. Various types of milk being investigated were from cereal and cow's origins. The cereal milk samples included corn, job's tear, rice, and soy milk, whereas the bovine milk included chocolate and fresh full-fat milk. Most samples exhibited monomodal size distributions, whereas corn milk displayed a slight deviation from monomodal characteristic. The mean particle sizes were detected to be approximately 0.4 μm for all cereal milk, except that they were approximately 0.5 μm for corn and all bovine milk. The application of SdFFF for micrometer size food particles was demonstrated for four types of flour samples, including corn, mung bean, rice, and tapioca flours. Significantly differences in the particle size characteristics of all flour samples were observed, by which corn, mung bean, rice, and tapioca yielded mean particle sizes of 16.7, 31.5, 13.5, and 19.9 μm, respectively. The ability of SdFFF for size separation of flours was confirmed by comparing the results obtained with those from scanning electron microscopy (SEM). Further, a new way to examine flour swelling was proposed. This study has demonstrated the potential value of SdFFF technique for food scientists.