150
sealed and sterilized. Mussel liquor obtained during extraction of the cooked meats
from the shell may be used instead of water to dilute the solution before adding to
the bottled meats (Waterman 1963). Similarly, white wine or wine vinegar may be
used as alternatives to distilled vinegar. Extracted mussel (P. viridis) meat was filled
sterilized into bottles and brine solution was added to remaining space. Closed bottles subjected to wet steam sterilization in pressure cooker for 1 h at 110 °C. It was
concluded mussel meat can be exposed to heat process in bottles to produce ready
to eat value added product and can be stored in room temperature up to 6 months
(Jayasooriya et al. 2014).
Thermal processing seems to be a good alternative to obtain a shelf-stable product with good nutritional value. However, changes in the composition of mussels
can be observed during the canning process. Heat treatments cause loss of water
from the mussel meat tissue because of protein denaturation, along with other trace
nutrients. This loss of water translates directly to loss of mass in the mussel meats
and substantial yield loss in the manufacturing process (Almonacid et al. 2012).
Almonacid et al. (2015) reported that the effects of the process on mussel composition are mainly caused by two mechanisms. One of these mechanisms is the material exchange between mussel meat and processing medium (water, steam, brine,
air) and the other is thermal inactivation of high temperature. Firstly, water loss and
increase in concentration are observed in the pre-cooking stage. On the other hand,
it is reported that a factor affecting water loss during heat treatment may be salt
concentration. Salt has been reported to increase the water retention capacity as well
as the solubility of proteins in muscle tissue by increasing the gaps between the filaments in the myofibrils (Hamm 1986). Moreover, process variables such as precooking time, brine salt concentration, and retort temperature had effect on the
ultimate drained weight in the final mussel product (canned mussel meats)
(Almonacid et al. 2012).
Due to the increase in this dry matter, the other components of the mussel
increase. Reduction of moisture content with an increase of protein, fat and ash
content was observed after thermal processing of green mussel (P. viridis) (Biji
et al. 2015). Thermal process has led to a reduction of amino acid and fatty acid
content in mussel samples (Biji et al. 2015).
The thermal processing of food may cause severe quality deterioration, such as
degradation in colour and texture, nutrient loss, cook loss (weight loss) and area
shrinkage, rendering the products reducing consumer acceptance. The most significant changes in mussel during heating result from protein denaturation. Protein
denaturation reduces water holding capacity, shrinks muscle fibres, and causes connective tissue degradation, subsequently leading to a harder and more compact tissue texture. There are structural differences between shellfish and mammalian
muscle. Therefore, the effect of thermal processing would be more detrimental to
shellfish. Paramyosin which forms the cores of the thick filaments in the adductor
muscle of invertebrates is covered by a cortical layer of myosin which is heat stable.
However, there is less connective tissue in invertebrate whole body compared to
vertebrate muscle also resulting in relatively higher textural changes resulting from
protein denaturation. Mussel meat composition is different from finfish and other
3 Molluscan Shellfish
sealed and sterilized. Mussel liquor obtained during extraction of the cooked meats
from the shell may be used instead of water to dilute the solution before adding to
the bottled meats (Waterman 1963). Similarly, white wine or wine vinegar may be
used as alternatives to distilled vinegar. Extracted mussel (P. viridis) meat was filled
sterilized into bottles and brine solution was added to remaining space. Closed bottles subjected to wet steam sterilization in pressure cooker for 1 h at 110 °C. It was
concluded mussel meat can be exposed to heat process in bottles to produce ready
to eat value added product and can be stored in room temperature up to 6 months
(Jayasooriya et al. 2014).
Thermal processing seems to be a good alternative to obtain a shelf-stable product with good nutritional value. However, changes in the composition of mussels
can be observed during the canning process. Heat treatments cause loss of water
from the mussel meat tissue because of protein denaturation, along with other trace
nutrients. This loss of water translates directly to loss of mass in the mussel meats
and substantial yield loss in the manufacturing process (Almonacid et al. 2012).
Almonacid et al. (2015) reported that the effects of the process on mussel composition are mainly caused by two mechanisms. One of these mechanisms is the material exchange between mussel meat and processing medium (water, steam, brine,
air) and the other is thermal inactivation of high temperature. Firstly, water loss and
increase in concentration are observed in the pre-cooking stage. On the other hand,
it is reported that a factor affecting water loss during heat treatment may be salt
concentration. Salt has been reported to increase the water retention capacity as well
as the solubility of proteins in muscle tissue by increasing the gaps between the filaments in the myofibrils (Hamm 1986). Moreover, process variables such as precooking time, brine salt concentration, and retort temperature had effect on the
ultimate drained weight in the final mussel product (canned mussel meats)
(Almonacid et al. 2012).
Due to the increase in this dry matter, the other components of the mussel
increase. Reduction of moisture content with an increase of protein, fat and ash
content was observed after thermal processing of green mussel (P. viridis) (Biji
et al. 2015). Thermal process has led to a reduction of amino acid and fatty acid
content in mussel samples (Biji et al. 2015).
The thermal processing of food may cause severe quality deterioration, such as
degradation in colour and texture, nutrient loss, cook loss (weight loss) and area
shrinkage, rendering the products reducing consumer acceptance. The most significant changes in mussel during heating result from protein denaturation. Protein
denaturation reduces water holding capacity, shrinks muscle fibres, and causes connective tissue degradation, subsequently leading to a harder and more compact tissue texture. There are structural differences between shellfish and mammalian
muscle. Therefore, the effect of thermal processing would be more detrimental to
shellfish. Paramyosin which forms the cores of the thick filaments in the adductor
muscle of invertebrates is covered by a cortical layer of myosin which is heat stable.
However, there is less connective tissue in invertebrate whole body compared to
vertebrate muscle also resulting in relatively higher textural changes resulting from
protein denaturation. Mussel meat composition is different from finfish and other
3 Molluscan Shellfish