Changes in cell wall galactosyl and soluble galactose content in tomato fruit stored in low oxygen atmospheres

Mature green tomato (Lycopersicon esculentum Mill.) fruit were stored in at mospheres of low oxygen (3.05 kPa; 3%) or air (control) at 20 degrees C. Th eir subsequent ripening behavior was compared in an effort to evaluate the temporal relationship among ethylene production, respiration, cell wall gal actosyl residue loss and the increase in free galactose that occurs during ripening. An increase in ethylene evolution and respiration, red color deve lopment, and loss in fruit firmness were delayed in fruit held in low oxyge n compared to control fruit held in air which showed normal ripening-relate d changes. Both the ripening-related decrease in cell wall galactosyl resid ues and the increase in soluble galactose were suppressed for 9 days in fru it held in low oxygen. However, after 9 days of storage, these processes di d commence and changed significantly by 13 days of storage. These results s uggest that either only relatively low baseline levels of ethylene were nec essary for it to exert its effect on these cell wall-related fruit ripening processes to occur or that the cell wall-related changes observed were eth ylene independent. It is clear that the levels of ethylene generally produc ed during the respiratory climacteric were not necessary to begin the proce sses associated with cell wall modification, such as the large net loss of galactosyl residues from the cell wall during tomato fruit ripening. (C) 19 99 Elsevier Science B.V. All rights reserved.