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Waste and Biomass Valorization
https://doi.org/10.1007/s12649-018-0357-z
ORIGINAL PAPER
Fish Oil Enzymatic Esterification for Acidity Reduction
Teresa M. Mata
1
· Daniela Correia
1
· Soraia Andrade
1
· Susana Casal
2
· Isabel M. P. L. V. O. Ferreira
2
·
Elisabete Matos
3
· António A. Martins
1
· Nídia S. Caetano
1,4
Received: 15 October 2017 / Accepted: 28 May 2018
© Springer Science+Business Media B.V., part of Springer Nature 2018
Abstract
The reduction of the fish oil acidity is a significant problem in the rendering industry, as the oil’s range of applications and
market value strongly depend on this parameter. In particular, the lower the acidity, the larger the oil’s market value. This
work aims to study the potential of enzymatic esterification for reducing the fish oil acidity, by converting the free fatty
acids into esters. Thus, four commercial lipases were used and a parametric study was performed to identify the best operat-
ing conditions, varying the reaction temperature, enzyme/oil mass ratio and alcohol/FFA mass ratio. All experiments were
performed in duplicate with a very good reproducibility of results. Results showed that Lipozyme TL 100L contributed to
greater acidity reduction (75% from an initial acid value of 10–14 mg KOH/g oil) for esterification at 40 °C, using ethanol
96% v/v, enzyme/oil and alcohol/FFA mass ratios of 0.01 and 3.24 w/w, respectively, reaching 3.13 mg KOH/g oil of final
acid value or 1.57% FFA content. The reaction kinetics were also studied and it was found that a second order rate law as
a function of the alcohol and oil concentrations is more adequate, with 35.44 kJ/mol of activation energy and 1.94 × 10
3
L
mol
− 1
min
− 1
of pre-exponential factor. In conclusion, this work shows that the enzymatic esterification to reduce the fish oil
acidity is technically feasible, increasing its market value.
Keywords Acidity reduction · Enzymatic esterification · Fish oil · Free fatty acids · Lipozyme TL 100L
Introduction
The fishing industry generates significant amounts of fish
by-products at different production stages, from fishing or
aquaculture production, to processing, preserving, storing,
transporting, and marketing or selling of fish and fish prod-
ucts. On a global scale, fisheries generate large quantities
of fish and derived products. In 2014, the total fish catch
was 167.2 Mt, of which 93.4 Mt corresponds to wild fish
and the remaining to aquaculture. A significant part of it is
processed by the fish processing sector, as for example the
canning industry. In 2015, the total production of fishmeal
and fish oil was respectively 4.731 and 0.856 Mt using as
raw materials 13.9 Mt of whole fish, around 3.7 Mt from
by-products of wild capture, and 1.9 Mt of by-products from
aquaculture production. The main producers of fishmeal are
South America (mainly Peru and Chile), followed by Asia
(in particular Thailand, Vietnam and China) and then by
Europe (mainly Denmark, Norway and Iceland). Concerning
fish oil, South America, followed by Europe and Asia are the
largest producers [1, 2].
Depending on the final product and/or application,
between 30–70% of the entire fish ends as by-products (e.g.,
heads, viscera and backbones) [1, 2]. Significant efforts have
been made to provide a suitable destination for this type
of by-products and applications or processes that generate
value from them, avoiding the discharge of polluting waste
into the environment and thus, reducing their potential envi-
ronmental impact [3, 4].
Production of animal feed is the most common destina-
tion for processed animal by-products, not only from fish
* Teresa M. Mata
tmata@fe.up.pt
1
LEPABE, Faculty of Engineering-University of Porto
(FEUP), R. Dr. Roberto Frias S/N, 4200-465 Porto, Portugal
2
LAQV/REQUIMTE, Laboratório de Bromatologia e
Hidrologia, Faculdade de Farmácia da Universidade
do Porto, Rua de Jorge Viterbo Ferreira, 228, Porto, Portugal
3
Soja de Portugal SGPS SA, Estrada Nacional 109 Lugar da
Pardala, 3880-728 S. João OVR, Portugal
4
CIETI, School of Engineering (ISEP), Polytechnic Institute
Porto (IPP), R. Dr. António Bernardino de Almeida S/N,
4200-072 Porto, Portugal
@Phil_Robichaud
@deepthiw
@JoseServera