An integrated microstructural, sensory and instrumental approach to describe potato texture

A new method was developed to objectively measure a range of microstructura l features in thin sections of raw, and cooked potatoes using light microsc opy and semi-automatic digital image analysis. Scanning electron microscopy was employed for qualitative visualization of the texture showing the degr ee of cell adhesion and cell wall softening. Sensory texture analysis and u niaxial compression tests were toed to determine the textural properties of cooked potato samples. Six conventionally and two organically grown potato cultivars were used in the study. Eight image features grouped the potato cultivar. With respect to three different structural qualities by principal component analysis. The most important structural differences between pota toes is characterized as a contrast between potatoes having a low volume fr action of cell walls (large cells), a small number of cells and starch grai ns, and large numbers of elongated cells. Another type of variation in the structural data grouped the potato cultivars with respect to volume fractio n of starch grains, volume function of galatinized starch, and formfactor o f cells. The volume fraction of raw and cooked starch and the formfactor of cells were significantly lowered during storage. Image features were corre lated with sensory and textural properties using multivariate data analysis (Partial Least Square Regression). Volume fraction of raw starch, volume f raction of gelatinized starch, and dry matter content were found to be high ly correlated with sensory geometrical qualities.,Mechanical sensory proper ties were found to be more correlated with a uniaxial compression measure ( stress at fracture) than was the image data. (C) 2000 Academic Press.