OPTIMIZATION OF OLIVE PASTE EXPRESSION - A STUDY OF VARIABLES AFFECTING EXPRESSION YIELD

The influence of some operating variables on olive paste expression ra te and yield has been investigated using a laboratory expression appar atus. Results show that compaction rate and cake thickness have a prim ary importance in determining the extraction rate. Temperature has a l imited effect. A pressure increase beyond 50.7 x 10(5) Pa is also of l ittle benefit. Data on product variables show that the rigid solids pl ay an important role and that the natural pit fragments content in oli ves is well below the optimal value. An extraction yield as high as 95 % was obtained by adding pit fragments up to 40% by volume of olive pa ste. This value is noteworthy because it was obtained during the expre ssion phase carried out at constant flow rate, while the expression ph ase carried out at constant pressure was not taken into account. Based on these results, an optimisation experimental design will be present ed and validated in a following work.