1. Dept. of Food Science; Univ. of Otago; P.O. Box 56 Dunedin 9054 New Zealand
2. AgResearch Ltd.; Grasslands Research Centre; Private Bag 11008, Manawatu Mail Centre Palmerston North 4442 New Zealand
3. Dept. of Microbiology and Immunology; Univ. of Otago; P.O. Box 56 Dunedin 9054 New Zealand
4. Dept. of Biochemistry; Univ. of Otago; P.O. Box 56 Dunedin 9054 New Zealand