Green fractionation and hydrolysis of fish meal to improve their techno-functional properties

A green strategy employing water as solvent has been adopted to obtain protein hydrolysates from fish meal (FM), its water-soluble fraction (WSP), and its non-water-soluble fraction (NSP). The techno-functional properties of the hydrolysates have been investigated and compared to hydrolysates obtained with Alcalase®. In general, SWH hydrolysates presented higher content of free amino acids and higher degree of hydrolysis, which reflected on the molecular size distribution. However, Alcalase® hydrolysates presented better solubility (from 74 ± 4% for NSP at pH = 2 up to 99 ± 1% for WSP at pH = 4–7). According to fluorescence experiments, FM and NSP hydrolysates showed the highest surface hydrophobicity, which has been related to better emulsifying properties and higher emulsion stability. The emulsions stabilized with 2%wt. of SWH-treated NSP showed the smallest particle sizes, with D[4,3] = 155 nm at day 0, and good stability, with D[4,3] = 220 nm at day 7, proving that water fractionation followed by SWH treatment is a good method to improve the techno-functional properties of the hydrolysates.

The authors acknowledge Sarval Bio-Industries Noroeste, S.A.U. (A Coruña, Spain) for kindly providing the fish meal used in this work and Novozymes A/S for kindly providing the enzyme Alcalase®. This work was supported by the Agencia Estatal de Investigación (AEI) [grant numbers PID2019-104950RB-I00 and PID2020-116716RJ-I00 ] by the AEI, Ministerio de Ciencia e Innovación (MICINN) and Next GenerationEU, [grant numbers TED2021-129311B-I00 and PDC2022-133443-I00 ] and the Junta de Castilla y León (JCyL) and the European Regional Development Fund (ERDF) [grant number BU050P20 ]. PB pre-doctoral contract is funded by JCyL and the European Social Fund (ESF) [ ORDEN EDU/1868/2022 ]. RM contract is funded by a Beatriz Galindo Research Fellowship [ BG20/00182 ]. Illera's post-doctoral contract is funded by AEI, MICINN and EU through project TED2021-129311B-I00 . OBR post-doctoral contract was funded by AEI through project PID2020–116716RJ-I00 .