350
sorbitol molecules, culminating in greater breaking elongation and lower tensile
strength of the resulting fi lms.
Potential applications of edible fi lms and coatings from biopolymers are to retard
transport of gases (O 2 and CO 2 ), water vapour, and fl avours for fruits and vegetables,
confectioneries, frozen foods and meat products. Edible fi lms can be formed by two
main processes, i.e., casting and extrusion (Hernandez-Izquierdo and Krochta
2008 ). The fi lm-formation process most often reported in the scientifi c literature is
the casting method. Briefl y, it involves dissolving the biopolymer and blending it
with plasticizers and/or additives to obtain a fi lm-forming solution, which is cast
onto plates and then dried by driving off the solvent. The extrusion method relies on
the thermoplastic behaviour of proteins at low moisture levels. Films can be produced by extrusion followed by heat-pressing at temperatures that are ordinarily
higher than 80 °C. This process may affect fi lm properties, but its use would enhance
the commercial potential of fi lms by affording a number of advantages over solutioncasting, e.g., working in a continuous system with ready control of such process
variables as temperature, moisture, size/shape, etc.
Fish gelatin fi lms has been produced from fresh water fi sh like trout (Kim and
Min 2012 ) and carp (Ninan et al. 2010 ) as well as from representatives of marine
species like salmon (Díaz et al. 2011 ) and Allaska Pollack (Shiku et al. 2004 ).
Studies on the production and characterization of fi lms using fi sh gelatins are quite
recent, and all fi sh gelatins have been observed to exhibit good fi lm-forming properties; yielding transparent, nearly colourless, water soluble, and highly extensible
fi lms (Avena-Bustillos et al. 2006 ; Carvalho et al. 2008 ; Gomez-Guillen et al. 2007 ;
Jongjareonrak et al. 2006 , 2008 ; Zhang et al. 2007 ; Pranoto et al. 2007 ; Rattaya
et al. 2009 ). Fish gelatin fi lms have also been envisioned as coatings for food
products (Berg et al. 1985 ).
There has been recently an increasing interest related to the fi lmogenic capacity
and applicability as food packaging (Arvanitoyannis 2002 ). The type of packaging
is an important factor to enhance the conservation and protection of perishable
foods, specifi cally in those cases where oxidative and microbiological deterioration
occurs. The majority of the packaging materials used to be of synthetic origin.
Nowadays environmental motivations have resulted in an increasing effort to fi nd
biodegradable edible materials, with an emphasis upon recycling industrial wastes,
or using renewable resources (Tharanathan 2003 ). This same sensitivity can be seen
in the recent scientifi c literature focused on edible and/or biodegradable fi lms with
numerous references related to gelatine, either pure or mixed with other biopolymers (see for review Gomez-Guillen et al. 2007 ).
Gelation, oxygen permeability, and mechanical properties of mammalian and
fi sh gelatin fi lms have been investigated in details by Avena-Bustillos et al. ( 2011 ).
Here, the results obtained from this comparative study are summarized. Mammalian
gelatin solutions had the highest gel set temperatures, followed by warm-water fi sh
and then cold-water fi sh gelatin solutions. These differences were related to concentrations of imino acids present in each gelatin, with mammalian gelatin having the
highest and cold-water fi sh gelatin the lowest concentrations. Mammalian and
warm-water fi sh gelatin fi lms contained helical structures, whereas cold-water fi sh
9 Marine Gelatins
sorbitol molecules, culminating in greater breaking elongation and lower tensile
strength of the resulting fi lms.
Potential applications of edible fi lms and coatings from biopolymers are to retard
transport of gases (O 2 and CO 2 ), water vapour, and fl avours for fruits and vegetables,
confectioneries, frozen foods and meat products. Edible fi lms can be formed by two
main processes, i.e., casting and extrusion (Hernandez-Izquierdo and Krochta
2008 ). The fi lm-formation process most often reported in the scientifi c literature is
the casting method. Briefl y, it involves dissolving the biopolymer and blending it
with plasticizers and/or additives to obtain a fi lm-forming solution, which is cast
onto plates and then dried by driving off the solvent. The extrusion method relies on
the thermoplastic behaviour of proteins at low moisture levels. Films can be produced by extrusion followed by heat-pressing at temperatures that are ordinarily
higher than 80 °C. This process may affect fi lm properties, but its use would enhance
the commercial potential of fi lms by affording a number of advantages over solutioncasting, e.g., working in a continuous system with ready control of such process
variables as temperature, moisture, size/shape, etc.
Fish gelatin fi lms has been produced from fresh water fi sh like trout (Kim and
Min 2012 ) and carp (Ninan et al. 2010 ) as well as from representatives of marine
species like salmon (Díaz et al. 2011 ) and Allaska Pollack (Shiku et al. 2004 ).
Studies on the production and characterization of fi lms using fi sh gelatins are quite
recent, and all fi sh gelatins have been observed to exhibit good fi lm-forming properties; yielding transparent, nearly colourless, water soluble, and highly extensible
fi lms (Avena-Bustillos et al. 2006 ; Carvalho et al. 2008 ; Gomez-Guillen et al. 2007 ;
Jongjareonrak et al. 2006 , 2008 ; Zhang et al. 2007 ; Pranoto et al. 2007 ; Rattaya
et al. 2009 ). Fish gelatin fi lms have also been envisioned as coatings for food
products (Berg et al. 1985 ).
There has been recently an increasing interest related to the fi lmogenic capacity
and applicability as food packaging (Arvanitoyannis 2002 ). The type of packaging
is an important factor to enhance the conservation and protection of perishable
foods, specifi cally in those cases where oxidative and microbiological deterioration
occurs. The majority of the packaging materials used to be of synthetic origin.
Nowadays environmental motivations have resulted in an increasing effort to fi nd
biodegradable edible materials, with an emphasis upon recycling industrial wastes,
or using renewable resources (Tharanathan 2003 ). This same sensitivity can be seen
in the recent scientifi c literature focused on edible and/or biodegradable fi lms with
numerous references related to gelatine, either pure or mixed with other biopolymers (see for review Gomez-Guillen et al. 2007 ).
Gelation, oxygen permeability, and mechanical properties of mammalian and
fi sh gelatin fi lms have been investigated in details by Avena-Bustillos et al. ( 2011 ).
Here, the results obtained from this comparative study are summarized. Mammalian
gelatin solutions had the highest gel set temperatures, followed by warm-water fi sh
and then cold-water fi sh gelatin solutions. These differences were related to concentrations of imino acids present in each gelatin, with mammalian gelatin having the
highest and cold-water fi sh gelatin the lowest concentrations. Mammalian and
warm-water fi sh gelatin fi lms contained helical structures, whereas cold-water fi sh
9 Marine Gelatins