physico-chemical and microbiological characterization of the natural fermentation of moroccanpicholinegreen olives variety [Caractérisation physico-chimique et microbiologique du processus de fermentation naturelle des olives vertes de la variété picholine marocaine]

The objective of this work is to study the natural physicochemical and microbiological fermentation process in the laboratory and at the industrial scale,in order to identify the improvement measures of the process. the experiment consisted of two batch lots of fermented olives where the first is debittered with lye and the second is not debittered. the both lots,made in the laboratory and at the industrial scale,were brined at 12% and kept at room temperature to undergo natural lactic fermentation. the results obtained showed a spontaneous development of lactic fermentation in the two assays indicated by the ph drop to ph 5 for the olivesdebittered in laboratory (ldl) and at the industrial scale (ldi),4.5 for non-debittered-olives fermented in laboratory (lndl) and 5.2 for non-debittered-olivesfermented at the industrial scale (lndi). in addition,the increase of acidity,the development of lactic acid bacteria (5.7 log cfu/ml for ldl and lndl,2.9 log cfu/ml for ldi and lndi) and the disappearance of coliforms were observed.these results indicated that the main factors regulating the fermentation process are room temperature and the residual lye in debittered-olives.indeed,debittering and low ambient temperature (10-14°c) delay the process; while temperaturesof 20 to 30°c are suitable for the rapid completion of natural lactic fermentation of green olives.