Value added fish by-products - Nordic Innovation

under harsher conditions. The storage modulus was increased 5 times compared to
commercial cold water fish gelatin.
Although the mechanical properties of gelatin from several fish species have been reported,
the effect of weight average molecular weight and the molecular weight distribution on the
mechanical properties of fish gelatin has only been studied to a limited extent (Gómez-Guilén
et al. 2002; Muyonga et al. 2004).
3.4.2 Mechanical properties of mammalian and fish gelatins based on their weight
average molecular weight and molecular weight distribution.
Acid porcine skin gelatins, lime bovine bone gelatins and gelatins from haddock
(Melanogrammus aeglefinus), saithe (Pollachius virens) and cod (Gadus morhua) were
compared according to their weight average molecular weight (Mw), polydispersity index,
dynamic storage modulus (G’) and Bloom value.
The dynamic storage modulus and Bloom value for all types of gelatin increased with
increasing weight average molecular weight. Due to fish gelatins considerably higher weight
average molecular weight and lower polydispersity, the dynamic storage moduli were
comparable to the corresponding values for acid porcine skin and lime bovine bone gelatins.
The Bloom values for gelatin from haddock, saithe and cod were determined to be 200, 150
and 100 g. Furthermore, the data presented in this study shows that removing low molecular
weight molecules from a gelatin sample increases the mechanical properties of the resulting
gel.
3.4.3 Mechanical properties of mammalian and fish gelatins as a function of the
contents of αααα-chain, ββββ-chain, low and high molecular weight fractions.
Principal component analysis (PCA) and partial least squares regression (PLSR) were used to
relate the mechanical properties with the molecular weight distribution. The results suggest a
linear relationship between the mechanical properties and the fractions of low molecular
weight (LMW) molecules, alpha-chains, beta-chains and high molecular weight (HMW)
molecules. The gel strength for cold water fish gelatin was positively correlated with the
51