SUMMARYThe acid‐catalyzed isomerization of pineapple fruit carotenoid pigments is influenced by any condition leading to loss of integrity of the cells of the fruit tissue. The swollen lower half of fully ripe, yellow, translucent fruit often will contain an appreciable fraction of isomerized pigment. Any post‐harvest handling of the fruit that causes bruising of the tissue will lead to pigment isomerization in the damaged areas. Canning completely isomerizes the carotenoid pigments. Frozen fruit contains a high proportion of isomerized carotenoids; after thawing, further change takes place until the spectrum is that of the isomerized or “canned” type