Tucuma is a native
Amazon palm strategic to the local
economy due
to its pulp and kernel oil utilization and its possibility to be used
in the recovery of degraded areas. The oil extraction generates a
postpressing cake with potential industrial utilization. The utilization
of this residue to generate new products is an opportunity to expand
the market of the fruit, aiming at an almost zero waste industrial
plant; moreover, it also helps to boost the local bioeconomy. The
present work aims to evaluate the hydroethanolic extraction of phenolic
compounds, with and without surfactant addition, from the tucuma pulp
postpressing cake. For this, the hydroethanolic extraction was carried
out at 62 °C, a solid:liquid ratio of 1:13, and an ethanol concentration
equal to 54%; at this condition two rhamnolipid (RML) type surfactants,
one with a majority of mono-RML and the other with a majority of di-RML,
was added. The hydroethanolic extraction without RML presented catechin,
epicatechin, and epigallocatechin. The addition of the RMLs in the
extraction media modulates the phenolic compounds extracted and their
quantities due to the relationship between the polarity of the phenolic
compound (Log P) and the hydrophilic–lipophilic
balance (HLB) of RMLs. The addition of mono-RML (HLB = 7.0) shifts
the polarity of the system and enables the extraction of more hydrophobic
compounds (epigallocatechin gallate, p-hydroxybenzoic
acid, and 3,4-dihydroxybenzoic acid) and catechin. The di-RML hydroethanolic
extract (HLB = 9.0) was the one with the highest number of compounds
(catechin, epigallocatechin gallate, epicatechin, epigallocatechin,
and p-hydroxybenzoic acid). This is probably due
to the higher surfactant HLB and the proportion of mono/di-RML. The
antifungal capacity of the extracts against fungi that cause postharvest
rot in oranges and strawberries was also evaluated. Both mono-RML
and di-RML hydroethanolic extracts presented higher inhibitory activity
than the sole hydroethanolic extract or the sole RML, when evaluated
against rot fungi. The RML extracts antifungal activity is probably
due to the synergism between the phenolic compounds and RML. This
is the first time that different RML congeners have been evaluated
to extract different categories of phenolic compounds with different
fungicidal actions.