Abstract
Californian-style black olives require a sterilization treatment that produces a carcinogenic contaminant, acrylamide. Thus, this compound was evaluated in two different olive cultivars using an electronic nose (E-nose). The sterilization intensity had a significant influence on the final phenol concentrations, acrylamide content, and volatile compounds. Increasing the sterilization intensity from 10 to 26 min (F0) reduced the phenol content, but it promoted acrylamide synthesis, leading to a wide range of this toxic substance. The Ester and phenol groups of volatile compounds decreased their content when the sterilization treatment increased; however, aldehyde and other volatile compound groups significantly increased their contents according to the thermal treatments. The compounds 4-ethenyl-pyridine, benzaldehyde, and 2,4-dimethyl-hexane are volatile compounds with unpleasant odours and demonstrated a high amount of influence on the differences found after the application of the thermal treatments. The “Manzanilla Cacereña” variety presented the highest amount of phenolic compounds and the lowest acrylamide content. Finally, it was found that acrylamide content is correlated with volatile compounds, which was determined using multiple linear regression analysis (R2 = 0.9994). Furthermore, the aroma of table olives was analysed using an E-nose, and these results combined with Partial Least Square (PLS) were shown to be an accurate method (range to error ratio (RER) >10 and ratio of performance to deviation (RPD) >2.5) for the indirect quantification of this toxic substance.
Highlights
Olive tree cultivation mainly extends throughout the Mediterranean area, with the commercial uses of olives mainly being the production of oil and table olives
This work aimed to assess the chemical composition in terms of phenol profile, antioxidant activity, acrylamide content, and volatile compounds in Californian-style black olives (“Manzanilla Cacereña” and “Hojiblanca” varieties) that have been submitted to different thermal treatments (10–26 min at 121 ± 3 ◦C) to find out whether the electronic nose (E-nose) can be used to determine acrylamide content
The phenolic compounds profile and antioxidant activity were performed after each thermal treatment and at the same time as when the acrylamide formation and the volatile compounds were being analysed
Summary
Olive tree cultivation mainly extends throughout the Mediterranean area, with the commercial uses of olives mainly being the production of oil and table olives. Table olive production exceeded 2.9 million tons during the 2019–2020 season, with the main producers being Spain, Egypt, Turkey, Algeria, Italy, Greece, and Portugal [1,2]. Californian-style black olive is one of the most important elaboration processes in the table olive sector. These olives are often consumed on pizzas, and canned olives are preserved and are used in other ways. To produce ripe black olives, the olives are harvested when they are green (unripe), and they are cured through exposure to a series of air oxidation and lye treatments to obtain debittered black olives. The olives are placed in cans and are subjected to a thermal sterilization treatment
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