58
In addition, mailard reaction occurs during drying. Blacking reactions reduce the
colour of the product and decrease its solubility and nutritional values; it causes
undesirable structural changes.
During the drying process, lipolysis and oxidation in lipids occur. The presence
of oxygen and water activity is effective on lipid oxidation during drying. Water
activity has an accelerating effect on lipid oxidation. It is reported that reduction of
water activity to about 0.3 significantly reduces oxidation reactions (Rahman and
Labuza 2007). The effect of oxygen depends on the porosity of the product. As the
porosity increases in freeze-dried products, they are more susceptible to oxidation.
During drying, aroma losses can also be seen in the products. Since the volatile
compounds that provide the flavour have a lower boiling point than water, they can
be removed from the product by evaporation during drying.
High quality dried shrimp should have low shrinkage and high rehydration capability. The shape and size of the products can vary considerably during drying.
Shrinkage during drying plays an important role in determining the quality of the
dried product. The shrinkage can be measured directly with a calliper or micrometre
and can be determined by changes in relevant parameters such as porosity and density. Recently, many studies have been carried out to identify the shrinkage behaviour of products with prediction models. On the other hand, image processing
techniques are used to measure the product shape (Yan et al. 2008). In a conducted
research, shrimp was dried by a hot air thin-layer dryer and a near-atmospheric pressure superheated steam dryer based on computer vision. In that study, the effects of
drying on appearance properties of products and relation between these properties
and moisture content of products were investigated. It was determined that the temperature of the drying medium influenced the drying rate and drying time as well as
on the field shrinkage and Feret’s diameter. High temperatures caused more irregular edge deformation of the samples (Hosseinpour et al. 2011).
Quality Changes in Dried Shrimp During Storage
In dried products, changes in protein and lipids together with water loss cause textural changes. Drying methods and drying parameters affect the textural changes.
The deterioration of the dried products occurs physical, autolytic, chemical, and
microbial ways.
Physical Spoilage
Due to perishability of dried products should be taken care. They can be damaged
very quickly by physical shocks. In addition, birds and other animals can damage
dried products by eating. Losses that may occur in dried products because of physical damage can be reduced by taking care in packaging and other operations
after drying.
2 Crustacean Shellfish
In addition, mailard reaction occurs during drying. Blacking reactions reduce the
colour of the product and decrease its solubility and nutritional values; it causes
undesirable structural changes.
During the drying process, lipolysis and oxidation in lipids occur. The presence
of oxygen and water activity is effective on lipid oxidation during drying. Water
activity has an accelerating effect on lipid oxidation. It is reported that reduction of
water activity to about 0.3 significantly reduces oxidation reactions (Rahman and
Labuza 2007). The effect of oxygen depends on the porosity of the product. As the
porosity increases in freeze-dried products, they are more susceptible to oxidation.
During drying, aroma losses can also be seen in the products. Since the volatile
compounds that provide the flavour have a lower boiling point than water, they can
be removed from the product by evaporation during drying.
High quality dried shrimp should have low shrinkage and high rehydration capability. The shape and size of the products can vary considerably during drying.
Shrinkage during drying plays an important role in determining the quality of the
dried product. The shrinkage can be measured directly with a calliper or micrometre
and can be determined by changes in relevant parameters such as porosity and density. Recently, many studies have been carried out to identify the shrinkage behaviour of products with prediction models. On the other hand, image processing
techniques are used to measure the product shape (Yan et al. 2008). In a conducted
research, shrimp was dried by a hot air thin-layer dryer and a near-atmospheric pressure superheated steam dryer based on computer vision. In that study, the effects of
drying on appearance properties of products and relation between these properties
and moisture content of products were investigated. It was determined that the temperature of the drying medium influenced the drying rate and drying time as well as
on the field shrinkage and Feret’s diameter. High temperatures caused more irregular edge deformation of the samples (Hosseinpour et al. 2011).
Quality Changes in Dried Shrimp During Storage
In dried products, changes in protein and lipids together with water loss cause textural changes. Drying methods and drying parameters affect the textural changes.
The deterioration of the dried products occurs physical, autolytic, chemical, and
microbial ways.
Physical Spoilage
Due to perishability of dried products should be taken care. They can be damaged
very quickly by physical shocks. In addition, birds and other animals can damage
dried products by eating. Losses that may occur in dried products because of physical damage can be reduced by taking care in packaging and other operations
after drying.
2 Crustacean Shellfish