Fróðskaparrit - 01.01.2005, Page 151

NÝTT INNAN VÍSINDI 2004
149
Durita Nielsen
Herring - living resources and good productions
Ph.D.-thesis at Danmarks Fiskeriundersøgelser, Afd. for Fiskeindustriel Forskning,
Lyngby, Denmark, 11 June 2004.
Summary
The main objective of this project was to
investigate to what extent the biological
differences between herring stocks in the
waters surrounding Denmark influence the
quality characteristics of marinated her-
ring.
Sensory analysis of marinated herring
processed within a few hours post mortem
showed fishing ground, i.e. areas with dif-
ferent herring stocks, to have no influence
on odour, flavour or texture, but there was
an apparent difference between herring
caught at the same place in two succeeding
years. Very small variations were encoun-
tered in the appearance of marinated her-
ring fillets, and therefore no further efforts
were made to develop a quality scheme for
marinated herring. The sensory properties
in this part of the study were influenced by
body weight, but not by age, sex or gonad
maturity. The influence of varying lipid
content, water content and liquid holding
capacity resulted in similar effects show-
ing the high correlation between these
properties. The results showed that the
variation in sensory quality observed by
the industry is not primarily due to fish-
ing ground. Therefore another study was
conducted using herring frorn commercial
catches to investigate the effect of onboard
storage methods.
Sensory evaluations of the raw material
from commercial catches showed clear ef-
fects from onboard storage methods. The
quality of iced herring was superior to the
quality of tank-stored herring during the
entire storage period. Off odours devel-
oped faster in tank-stored herring, and
tank-storage resulted in more discoloured
gills and duller skin than ice storage. Ice
storage on the other hand induced more
blood on gill covers. Large spawning her-
ring with high lipid contents had higher
quality than small immature herring with
low lipid content. The high lipid content
was correlated to low scores for all de-
scriptors except “blood on gill cover”,
which was the only descriptor not depend-
ent on biological or chemical parameters.
Some shortcomings were recognised with
the QIM scheme. It could clearly differ-
entiate between the quality of iced and
tank-stored herring, but could not be used
to calculate the remaining shelf life. The
variations in raw material quality were re-
trieved in the sensory properties of mari-
nated herring fillets. Marinated herring
fillets produced from iced herring smelled
and tasted more of fresh herring and were
juicier than herring from storage tanks.
This study also showed the sensory pro-
file of marinated herring from the North
Sea to be influenced by season and the