Identification of mitigation strategies to reduce acrylamide levels during the production of black olives

Californian-style processes are widely applied to the elaboration of black ripe olives in the table olive industry. During this procedure, a carcinogenic contaminant known as acrylamide is generated in thermal oxidation. The content of this compound can be modified according to the stage of processing. The present study evaluates the conditions pertaining to different phases of the elaboration process with the aim of identifying optimal conditions for the production of table olives with the lowest acrylamide concentration possible. ‘Hojiblanca’ variety olives were used. Olives were harvested at two different maturation stages, specifically, the green and yellow-green stages. Olives with yellow-green maturation indices had higher acrylamide concentrations than green table olives. Significant reductions in the contaminant were observed as storage time increased, with green olives stored for 21 months displaying the lowest acrylamide levels. Acrylamide was also decreased by spraying olives with water (18 % reduction) and washing them with water heated to 25 °C for 40 min (36 % reduction). Following treatment with lye during the packaging and preparation of olives, unpitted olives contained 12–31% more acrylamide than pitted olives and 42–62% more than sliced olives. Outcomes were the same for olives canned both with and without brine. The presence of CaCl2 and the addition of greater NaCl concentrations (from 2% to 4% w/v), increased the acrylamide content in all olive formats. This increase was not observed in olives not stored in liquid. Outcomes reported here are valuable for redesigning the elaboration process of industrial black ripe olives and allowing producers to manufacture better-quality products with significantly reduced acrylamide concentrations.

The research leading to this paper received financial support from Junta de Extremadura (project IB18125) which is co-funded by the European Regional Development Fund. Furthermore, this work has also been supported by research groups belonging to Junta de Extremadura (GR18162).

Peer reviewed