Monitoring physicochemical and sensory attributes during debittering of stoned green olives
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abstract
Stoned green olives are traditional table olives produced in the Northeast of Portugal. They are highly
appreciated due to their organoleptic characteristics and levels of complex phenols endowed with strong
antioxidant activity, having a significant agro-economic relevance. During the natural debittering
process, stoned olives are immersed in water, which is changed (each 1-2 days), leading to a reduction
of the initial bitterness and increase of sweetness, turning these green olive edible [1]. Monitoring total
phenols contents, the bitterness index as well as the basic sensorial attributes through this washing
stage is very important. In this work, the debittering process of 110 samples of stoned green olives (cvs.
Cobrançosa and Negrinha de Freixo), was monitoring during 20 days. After each debittering-washing
time-period (water changed each 2-days) bitter, pungent and sweet intensities sensations were
assessed by trained panelists. Furthermore, the bitterness index and total phenols contents were also
evaluated spectrophotometrically. Figure 1 shows the trends observed for the sensory attributes and
chemical parameters along the debittering-washing process. From the boxplots (Figure 1), it is clear that
bitterness index and total phenols contents significantly decreased with the time, which could be directly
related to the observed decrease of the bitter taste intensity (for both olive cultivars) while the decrease
of the pungent sensation could be related with the decrease of the total phenols contents, mainly
influenced by the increase of the sweet sensation. Furthermore, as can be inferred, the initial bitterness
and pungency intensities of cv. Cobrançosa olives were higher than those from cv. Negrinha de Freixo.
Nevertheless, after 16-20 days of debittering-washing steps, the bitter and pungent intensities perceived
by the trained panelists, for both olive cultivars, were of the same order of magnitude, showing that the
debittering procedure adopted was successful and technologically consistent.
This research was financially supported by Associate Laboratory LSRE-LCM -
UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC) and by Project
UID/BIO/04469/2013 –CEB, and strategic project PEst-OE/AGR/UI0690/2014–CIMO all funded by European
Regional Development Fund (ERDF) through COMPETE2020–Programa Operacional Competitividade e
Internacionalização (POCI)–and by national funds through FCT–Fundação para a Ciência e a Tecnologia. Ítala
M.G. Marx acknowledges Fundação para a Ciência e a Tecnologia (FCT) through FCT PhD reference:
(SFRH/BD/137283/2018).
