The Aspergillus aculeatus pectinesterase enzyme is used to modify the texture of plant derived products. It is produced by A. oryzae transformed with the cloned full length cDNA of A. aculeatus encoding pectinesterase. It was subjected to a series of toxicological tests to document safety in use. The enzyme preparation was not found to be mutagenic in the Ames test, and did not cause chromosomal damage in a human lymphocyte assay. In a 13-week oral-toxicity study in rats, with daily dosages up to 10 g enzyme preparation kg body weight (b.w.), there were no adverse effects on mortality, clinical signs, body weight, food or water consumption, ophthalmoscopic findings, haematology or clinical chemistry. There were also no notable necropsy or histological findings. Statistically significant increases in heart weight were noted in male animals treated with 5 or 10 g enzyme preparation/kg b.w./day, following covariance analysis. However, this was not considered to be related to treatment with the enzyme preparation. The issue of the levels of free liberation of methanol in products processed with pectinesterase is addressed, and it is concluded that, from a nutritional and physiological point of view, free as well as bound methanol must be considered.