Antioxidant Activities of Sicilian Prickly Pear (Opuntia ficus indica) Fruit Extracts and Reducing Properties of Its Betalains: Betanin and Indicaxanthin. Daniela Butera, Luisa Tesoriere, Francesca Di Gaudio, Antonino Bongiorno, Mario Allegra, Anna Maria Pintaudi, Rohn Kohen and Maria A. Livrea, J. Agric. Food Chem., 2002, 50 (23), pages 6895–6901, doi:10.1021/jf025696p
Antioxidant compounds from four Opuntia cactus pear fruit varieties. Joseph Ο Kuti, Food Chemistry, May 2004, Volume 85, Issue 4, Pages 527–533, doi:10.1016/S0308-8146(03)00184-5
Composition of pulp, skin and seeds of prickly pears fruit (Opuntia ficus indica sp.). Radia Lamghari El Kossori, Christian Villaume, Essadiq El Boustani, Yves Sauvaire and Luc Méjean, Plant Foods for Human Nutrition, 1998, Volume 52, Issue 3, pages 263-270, doi:10.1023/A:1008000232406