Observation of the Oil Content of Fried Lotus (Nelumbo nuciferaGaertn.) Root Slices by Confocal Laser Scanning Microscopy Based on Three-Dimensional Model

Abstract

Microstructures of fried lotus root slices were observed using confocal laser scanning microscopy (CLSM) in fluorescent modes. The three-dimensional (3D) cell structure and morphology of samples were analyzed, for the first time, using 3D reconstructed fluorescent images to determine the cell morphology, oil location and content. Results show that oil was mainly located in the intercellular spaces, broken cells and voids created by the cutting operation, as well as in the wrinkles and distortions caused by the water leakage after frying, cell detachment, starch swelling and rapid dehydration of the first cell layer. Besides, the image stacks obtained by CLSM were processed independently to determine the oil-volume measurements using objective threshold selection. The 3D image data were used for quantitative characterization of oil content by calculating the oil volume. A good correlation between the CLSM results and normal analysis is obtained with the correlation coefficients of 0.892 and 0.875 in calibration and predication, respectively. This study demonstrated that CLSM could determine the oil location and content in fried snacks. Practical Application One of the most important quality parameters for the oil uptake of vacuum fried (VF) and atmospheric fried (AF) lotus root slices were determined and compared under the same frying condition. Microstructures of fried root slices of lotus (Nelumbo nucifera Gaertn.) were observed using CLSM in fluorescent modes. The three-dimensional (3D) cell structure and morphology of samples were analyzed, for the first time, using 3D reconstructed fluorescent images to determine the cell morphology, oil location and content. This optimal way of fried and fired condition was selected by the analytical results of CLSM.