The pH and Total Fat Values of Fish Meat in Different Iced Storage Period
This study was aimed to investigate the effect of different iced storage periods on the pH and total fat values of fish meat. Because, these parameters are very important for shelf life and consumer choice. In this study, 30 meat samples from fish (Trachurus trachurus L. 1758) were used. The data was collected for 3 iced storage period that initial (fresh), 1 and 2 week. The concentrations of total fat were higher (p<0.05) for initial period than other weeks. However, the concentrations of pH were also lower (p<0.05) for this period. During the initial storage period the pH was consistently low (6.2) and this may have contributed to the increased shelf-life of the fish used in this trial. The increase in pH after initial period was associated with the state of rapid spoilage of the fish. In this study, the pH concentrations close to neutral of meat from fish for second week may be advantage for eating quality. However, this pH level is disadvantage for shelf life of product. The high amounts of fat in the initial period may have a negative effect upon consumer's preference.
Information about handling, processing and storage techniques, including time/temperature
histories that can affect the freshness and quality of the products is very
important for the partners in the chain (Groom, 1990;
Comforth, 2007; Umberger et al.,
2003). Identifying an optimum meat source according to biochemical parameters
at the retail level may allow for production of a more uniform product in the
retail setting and allow producers to make sound decisions on the appropriate
meat of animals (Amer et al., 1997; Cicek,
2007; Sweeter et al., 2005). The time passed
after catch and the temperature history of fish is very often the key factor
determining the final quality characteristics of fish products (Olafsdottir
et al., 2004). Recently, some researchers (Abbas
et al., 2006) determined the shelf life and freshnesss of stored
at 0-10°C for 28 days and have found that from sensory and pH point of view
under various storage temperatures, the higher the storage temperature the faster
is the increase in both sensory and pH values which can be used as measurements
for quality deterioration and shelf life prediction in the fish marketing sector.
The changes in fish meat biochemical components such as pH and total fat from
different iced storage period for retail consumers have not been discussed.
Therefore, these parameters have been determined for different iced storage
period in this study. This study was aimed to investigate the effect of different
iced storage periods on the pH and total fat values of fish meat. Because, this
parameters are very important for shelf life and consumer choice.
MATERIALS AND METHODS
Fish materials (Trachurus trachurus L. 1758) were obtained from fish
market in Ordu, in the Black Sea coast of Turkey and total 30 fish samples were
used in this study. The fish were stored in ice for over a period of 2 weeks.
Changes in lipid and pH values of the fish were determined during the storage.
At least 10 samples were drawn from the batch for each sampling and analyzed
their lipid and pH values. Sampling was done when the fish was received, first
week and second week of storage.
Lipids were extracted according to modified Bligh and Dyer method (Hanson
and Olley, 1963). Basically, 1 g fish sample was minced with 10 mL of distilled
water and pH was measured by pH meter 7020 (Electronic Instruments Ltd., England).
All of data are indicated as Mean±SEM. Comparisons were done by using
Duncan test with help of the SPSS (Norusis, 1993).
RESULTS AND DISCUSSION
The concentrations of total fat were higher (1.8%) for initial period than
other weeks (1.6 and 1.5%, respectively for 1 and 2 weeks) (Table
1). However, the concentrations of pH were lower (p<0.05) for this period
(6.2 for initial vs. 6.5 and 6.8 for following weeks).
The low muscle pH in the initial period reflected the good nutritional state
of fish. The typical pH of live fish muscle ≈ 7.0. During the initial
storage period, the pH was consistently low (6.2) and this may have contributed
to the increased shelf-life of the fish used in this trial. However, at the
first week of storage pH started to increased, reaching a value of 6.8 by the
end of the trial. The increase in pH values after initial period reflected the
production of alkaline bacterial metabolites in spoiling fish and coincided
with the increase in Total Volatile Basic Nitrogen (TVBN) (Kyrana
et al., 1997).
The increase in pH after initial period was associated with the state of rapid
spoilage of the fish (Kyrana and Lougovious, 2002).
However currently, instrumental evaluation had take over most of the sensorial
evaluation by human. This is because the estimation of quality of fish based
on traditional measures can be difficult. The method to determine the quality
parameters of fish are also often complicated and time consuming and the result
are often obtained after the product have been distributed to the consumer.
Compared to the evaluation by using the instruments was much more faster, easy
to handle, has the ability to carry out many samples as routine and more reliable
compare to human evaluation even though they are trained (Simeonidou
et al., 1997).
In this study, the pH concentrations close to neutral of meat from fish for
second week may be advantage for eating quality. However, this pH level is disadvantage
for shelf life of product. The shorter shelf life negatively effects on salability
of meat. The meat quality traits must include suitable pH that indicates eating
quality and shelf life. Lower pH value is related to greater losses during further
meat processing and high pH value is related to shorter shelf life but also
better eating quality (Gregory et al., 1994).
Abbas et al. (2006) determined the shelf life
and freshness of stored at 0-10°C for 28 days and have found that from sensory
and pH point of view under various storage temperatures, the higher the storage
temperature the faster is the increase in both sensory and pH values which can
be used as measurements for quality deterioration and shelf life prediction
in the fish marketing sector.
Biochemical parameters of fish meats from different Iced
|Data is expressed as Mean±SE. Means followed by
different superscripted letters differ significantly at p<0.05
The high amounts of fat in the initial period may have a negative effect upon
consumer's preference. The consumer preference on meat salability is reduced
when meats have excessively fat (Amer et al., 1997).
While increases in fat and pH may be desirable over some range, excessive levels
of these traits can be undesirable.
The changes in chemical components provide a potential opportunity to manipulate
economic return in meat to enhance quality characteristics and, consequently,
commercial gain. According to results from this study, we can explain that pH
can act as indicators of the fish freshness as it start with low reading at
the early stage of storage which means the nutritional state was still good
and then increased when the fish had been stored for certain period of time.
So, by checking the pH of the fish after a certain period of storage can determine
the state of it freshness. Meat quality traits including fat and pH will be
important in determining meat price and profits in the near future.
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