Characterization of preservation solutions of Spanish black olives and potential for acrylamide formation in processed products

Authors: BRENES-ÁLVAREZ, MERCEDES - Instituto De La Grasa; Johanningsmeier, Suzanne; Bough, Raven; MEDINA, EDUARDO - Instituto De La Grasa; ROMERO, CONCEPCION - Instituto De La Grasa

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/2025
Publication Date: 3/26/2025
Citation: Brenes-Álvarez, M., Johanningsmeier, S.D., Bough, R.A., Medina, E., Romero, C. 2025. Characterization of preservation solutions of Spanish black olives and potential for acrylamide formation in processed products. Food Control. 175:111307. https://doi.org/10.1016/j.foodcont.2025.111307.
DOI: https://doi.org/10.1016/j.foodcont.2025.111307

Interpretive Summary: Acrylamide, a genotoxic compound and a probable carcinogen, is formed during the sterilization stage of black olive processing, similar to that reported for many other heated foods. This study characterized olive preservation solutions to determine the relationship between their composition and the potential formation of acrylamide in processed olives. The chemical and microbial profile of 37 preservation solutions from 4 different Spanish factories were analyzed along with acrylamide formation in the sterilized solutions. Great variability was found among samples and factories, not only in chemical parameters but also in microbial predominance. While individual components could not be used to predict acrylamide formation, a statistical model that incorporated all of the compositional variables accounted for ~90% of the variation in acrylamide content. Acrylamide levels in black olives corresponded to that formed in the preservation brines. Therefore, sterilization of these solutions prior to final olive processing could be a reliable method to estimate acrylamide formation in the final product. This new analytical approach offers processors a means to manage acrylamide levels effectively in their products.

Technical Abstract: The aim of this study was to characterize olive preservation solutions and establish a relationship between their composition and the potential formation of acrylamide in processed olives. The chemical and microbial profile of 37 preservation solutions from 4 different Spanish factories were analyzed along with acrylamide formation in the sterilized solutions. Amino acids, sugars, organic acids, phenolic and oleosidic compounds and acrylamide were monitored by HPLC, and yeasts and bacteria were analyzed by using metagenomic approach. Great variability was found among samples and factories, not only in chemical parameters but also in microbial predominance. While individual amino acids, phenolic and oleosidic compounds, sugars and organic acids did not show significant correlation with the acrylamide formed, a multivariate model accounted for ~90% of the variation in acrylamide content using the NIPALS model with 7-fold cross validation. Glucose, asparagine and hydroxytyrosol had high positive coefficients. Moreover, it must be noted that the acrylamide level depended on the pH during sterilization, with a maximum at pH 7 and lesser amounts formed at pH 4 and 9, which is in accordance with Maillard reactions behavior. Likewise, ultrafiltration assays revealed that the precursors of acrylamide formation in the preservation solutions must possess low molecular weight (<1000 Da). Sterilization of these solutions prior to the darkening stage could be a reliable method to estimate acrylamide formation in the final product. Therefore, processors could change the elaboration method of black ripe olives for some batches of olives expected to have a potential high final acrylamide content.