326
rarely patched and one directionally arranged collagen fi bers, in which specifi cally
triple helical assemblies of collagen fi brils were found. On the contrary, the relatively aged region of the rostral fi eld close to the scalar focus displayed randomly
directed and densely packed collagen fi bers, in which loosened- and deterioratedhelical assemblies of collagen fi brils were mostly found,” (Youn and Shin 2009 ).
Interestingly, comparisons between the stable isotope composition of carbon in
collagen excised from juvenile (freshwater) and adult (marine) portions of scales
from Atlantic salmon Salmo salar demonstrated that c. 75 % of carbon analysed
in the ‘juvenile’ portion of the scale derives from older collagen. Scale collagen
analyses were effectively restricted to the last season of growth (Hutchinson and
Trueman 2006 ).
Isolation and characterisation of fi sh scale collagen is also well described (see for
review Toshiyuki et al. 2003 ; Nagai et al. 2004 ; Zhang et al. 2011 ; Mori et al. 2013 ).
In the past, the fi rst step for extracting collagen from fi sh scales was to remove the
fat with an organic solvent, such as acetone. The second step was removal of the
hydroxyapatite by acidity solution; and the third step was fi ltration to gain the crude
collagen (Wu and Chai 2007 ). Recently, the novel extraction of collagen from fi sh
scales with papain under ultrasonic pretreatment was reported (Jiang et al. 2012 ).
The results showed that the optimum conditions for collagen extraction from fi sh
scales were: ultrasonic pretreatment time 4 min, ratio of papain to fi sh scales 4 %,
temperature 60 °C and extraction time 5 h. Under the optimum conditions the
extraction rate of collagen reached 90.7 %.
Unfortunately, little attention was paid to the other proteinaceous components of
fi sh scales like ichtylepidin (Burley and Solomons 1955 ). Mörner ( 1898 ) has shown
that the scales of many species of fi sh contain, in addition to mineral matter and collagen, a peculiar albuminoid. To this albuminoid he gave the name ichtylepidin . Mörner
prepared his ichthylepidin in the following way: “the clean scales were digested at
room temperature with a large excess of 5 % hydrochloric acid, 0.05 % caustic potash,
and 0.01 % acetic acid. Each digestion extended over several days. This treatment
removed soluble proteins, most of the guanin, the chrondroitin- sulphuric acid, and the
inorganic matter. The residual scales were then digested with 0.1 % hydrochloric acid
at 40 ° C. The residue thus freed from collagen was washed with alcohol and ether, and
dried. The substance so obtained (pure ichthylepidin) was insoluble in boiling water, in
cold dilute acids, and in alkalies; but it was soluble in hot solutions both of dilute acids
and alkalies, and in the cold concentrated solutions of the same. It gave a strong
Millon’s reaction and contained much loosely combined sulphur (as shown by the
blackening of the substance when boiled with an alkaline solution of lead acetate),”
(Green and Tower 1901 ; see also Mörner 1898 [Ger]). By the two latter reactions the
presence of ichthylepidin may, according to Mörner, be determined in fi sh scales
(Green and Tower 1902 ). The relation between content of ichtylepidin to collagen is
fi sh scales are reported as 24–76 % (Green and Tower 1902 ).
Ichtylepidin isolated from carp scales contains 50,87 % C; 6,56 % H; 15,69 % N;
1,02 % S, and 26,8 % O (Abderhalden and Voitinovic 1907 ). As reported by Kalyani
( 1997 ), Winter in 1954 made a complete analysis of the Pilchard scale ichthylepidin
8 Marine Collagens
rarely patched and one directionally arranged collagen fi bers, in which specifi cally
triple helical assemblies of collagen fi brils were found. On the contrary, the relatively aged region of the rostral fi eld close to the scalar focus displayed randomly
directed and densely packed collagen fi bers, in which loosened- and deterioratedhelical assemblies of collagen fi brils were mostly found,” (Youn and Shin 2009 ).
Interestingly, comparisons between the stable isotope composition of carbon in
collagen excised from juvenile (freshwater) and adult (marine) portions of scales
from Atlantic salmon Salmo salar demonstrated that c. 75 % of carbon analysed
in the ‘juvenile’ portion of the scale derives from older collagen. Scale collagen
analyses were effectively restricted to the last season of growth (Hutchinson and
Trueman 2006 ).
Isolation and characterisation of fi sh scale collagen is also well described (see for
review Toshiyuki et al. 2003 ; Nagai et al. 2004 ; Zhang et al. 2011 ; Mori et al. 2013 ).
In the past, the fi rst step for extracting collagen from fi sh scales was to remove the
fat with an organic solvent, such as acetone. The second step was removal of the
hydroxyapatite by acidity solution; and the third step was fi ltration to gain the crude
collagen (Wu and Chai 2007 ). Recently, the novel extraction of collagen from fi sh
scales with papain under ultrasonic pretreatment was reported (Jiang et al. 2012 ).
The results showed that the optimum conditions for collagen extraction from fi sh
scales were: ultrasonic pretreatment time 4 min, ratio of papain to fi sh scales 4 %,
temperature 60 °C and extraction time 5 h. Under the optimum conditions the
extraction rate of collagen reached 90.7 %.
Unfortunately, little attention was paid to the other proteinaceous components of
fi sh scales like ichtylepidin (Burley and Solomons 1955 ). Mörner ( 1898 ) has shown
that the scales of many species of fi sh contain, in addition to mineral matter and collagen, a peculiar albuminoid. To this albuminoid he gave the name ichtylepidin . Mörner
prepared his ichthylepidin in the following way: “the clean scales were digested at
room temperature with a large excess of 5 % hydrochloric acid, 0.05 % caustic potash,
and 0.01 % acetic acid. Each digestion extended over several days. This treatment
removed soluble proteins, most of the guanin, the chrondroitin- sulphuric acid, and the
inorganic matter. The residual scales were then digested with 0.1 % hydrochloric acid
at 40 ° C. The residue thus freed from collagen was washed with alcohol and ether, and
dried. The substance so obtained (pure ichthylepidin) was insoluble in boiling water, in
cold dilute acids, and in alkalies; but it was soluble in hot solutions both of dilute acids
and alkalies, and in the cold concentrated solutions of the same. It gave a strong
Millon’s reaction and contained much loosely combined sulphur (as shown by the
blackening of the substance when boiled with an alkaline solution of lead acetate),”
(Green and Tower 1901 ; see also Mörner 1898 [Ger]). By the two latter reactions the
presence of ichthylepidin may, according to Mörner, be determined in fi sh scales
(Green and Tower 1902 ). The relation between content of ichtylepidin to collagen is
fi sh scales are reported as 24–76 % (Green and Tower 1902 ).
Ichtylepidin isolated from carp scales contains 50,87 % C; 6,56 % H; 15,69 % N;
1,02 % S, and 26,8 % O (Abderhalden and Voitinovic 1907 ). As reported by Kalyani
( 1997 ), Winter in 1954 made a complete analysis of the Pilchard scale ichthylepidin
8 Marine Collagens