1. Laboratorio de Nutrición, Instituto Nacional de Tecnologia Agropecuaria, EEA Pergamino-INTA, Argentina.
2. Dept. Food Science, Pennsylvania State University, University Park, PA 16802.
3. Corresponding author. Phone: 814-865-5644. Fax: 814-863-6132. E-mail: kus2@psu.edu