Surface Characteristics of Leafy Vegetables and Their Effects on Salmonella Attachment

Abstract

Leafy vegetables exhibit non-uniform surfaces and are structured with interconnected networks of veinlets or wrinkle characteristics, making the quantification of the changes rather difficult. In this study, attempt was made to quantify the surface topographical features of leafy vegetable. Image analysis was used to determine the characteristic of vegetable surface. In term of surface area (A), the results were compared with those correlated with the data obtained by a conventional measurement method. It was also performed to determine fractal dimension (FD) and roughness value (R) to describe the behavior of bacteria attached on the vegetable surface. The results showed that different leafy vegetable (basil, lemon basil, peppermint and cabbage) did not have a significant effect on Salmonella attached on surface. Dorsal side (upper side) of leaves exhibited higher R and lower FD than ventral side (lower side). It led to number of Salmonella attached on upper side of leaves showed higher than their lower side. From Pearson's correlation, FD could relate well with the number of Salmonella attached on surface of vegetable. FD showed the highest correlation (-0.78-(-0.97)) follow by A (0.77-0.86) and R (0.61-0.87), respectively. Therefore, the parameters from image analysis were found to be good indicator to describe the physical characteristics of leafy vegetable.