Proceeding of 2013 International Seminar on Climate Change and Food Security ISCCFS 2013
Palembang, South Sumatra -Indonesia, 24-25 October,2013
138
3.2. Texture elasticity
The research results showed that fish formulation produced pempek with lower value of texture elasticity. High temperature had effect on higher value of texture elasticity. Initial measurement of
pempek texture gave average value in the range of 317.2 to 811.6. The values of pempek texture were decreased after 48 hours storage in the range of 216.2 to 586.2. The effect of formulation, temperature and
shelf life on the change of pempek texture elasticity was described by the following model :
Y = - 17,417 + 109,892 X
1
+ 3,710 X
2
– 4,301 X
3
R
2
= 0,977.............................................. 4 Texture is an important characteristics in evaluation of pempek quality. Higher addition of tapioca flour
would increased starch gelatinization capacity due to availability of water and heat which results in elastic texture of pempek. Tapioca flour has function as binder agent that capable to improve texture, but excessive
addition of tapioca flour will results in elastic texture. Protein content has significant effect on pempek texture. Protein content within fish flesh that has effect on texture is actomiosin. Prevention of actomiosin
denaturation is one of the most important factor to take into account. One method to prevent actomiosin denaturation is by using highly fresh fish as raw material Wang, 2011 and maintaining constant low
temperature during handling Astawan
et al
., 1996. Starch has two fractions which consisted of amylose and amylopectin. Amylose has effect on gel hardness, whereas amylopectin has effect on gel elasticity.
3.3. Total Volatile Nitrogen mg100g
The research results showed that fish formulation produced pempek with higher value of total volatilenitrogen. High temperature had effect on lower value of total volatilenitrogen. Measurement results
of total volatilenitrogen of pempek were in the range of 6.11 to 8.52. The values of total volatilenitrogen of pempek were increased after 48 hours storage in the range of 12.89 to 19.76. The effect of formulation,
temperature and shelf life on the change of total volatilenitrogen of pempek was described by the following model :
Y = 3,501 + 0,70X
1
– 1,030 X
2
+ 0,409 X
3
R
2
= 0,992........................................................... 5 Total volatile nitrogen is one of parameter to determine quality deterioration of fish and fish derived
products. TVN measurement on pempek was conducted to determine the rottenness indication of protein containing in food product. The increase of TVN concentration on pempek during storage was due to protein
degradation and its derivatives by proteolytic bacteria activity that decompose protein into simpler protein coumpounds which consisted of highly volatile bases such as ammonium, trimethylamine, histamine, indole,
H
2
S andskatol as well as breakdown of TMAO Trimethyl Amine Oxide into TMA TrimethylAmine. The acceptable maximum concentration of TVN for food products was 20 mg100 gram Castro
et al.
, 2012 and about 30-35mg100gramin case of fish flesh Huss.1988
in
Kaba, 2006 ., Amegovu
et al.,
2012. Pempekthat had been stored for 24 hours was still consumable because it hasTVN maximum concentration of 18 mg100
gram material, whereas 36 hours storage was in the range of 20 to 24 mg100 gram material and 48 hours storage was in the range of 25 to 29 mg100 gram material. Therefore, it can be concluded that pempek
stored for 48 hours was started to deteriorate and no longer consumable.
3.4. pH
The research results showed that fish formulation produced pempek with lower value of pH and high temperature results in higher value of pH. The pH measurement results for pempek were in the range of 6.68
to 6.93.The pH values of pempekwere decreased after 48 hours storage in the range of 5.62 to 6.32. Therefore, pempek is classified as low acid food. The effect of formulation, temperature and shelf life on the
change of pH of pempekwas described by the following model :
Y = 6,908 + 0,002 X
1
+ 0,000944 X
2
- 0,016 X
3
R
2
= 0,892................................................... 6 The pH of pempekwas depend on pH of fish flesh material, i.e lower fish quality results in lower pH.pH
value for fresh fish is 6.9 and for unfresh fish is in the range of 6.4 to 6.9 due to decrease of glycogen concentration. According to Wang 2011, fish gel formation of product is not occurred if pH value is less
than 6. The decrease of pH value during storage was due to decomposition of protein and carbohydrate into simpler compundsas a results of microbe and enzyme activities. This was in accordance to the increasing
numbers of total microbes at the end of storage period.
Proceeding of 2013 International Seminar on Climate Change and Food Security ISCCFS 2013
Palembang, South Sumatra -Indonesia, 24-25 October,2013
139
3.5. Total Microbe TPC
The highest value of total microbes at initial shelf life was found in treatment combination of formulation 1 and 95
C with magnitude 9.1x10
4
coloniesgram, whereas the lowest total microbes was found in treatment combination of formulation 4 and 75
C with magnitude 1.0x10
4
coloniesgram. Results of total microbes analysis at 24 hours storage from several treatment combinations had indicated some deterioration,
especially at pempek formulation containing higher fish flesh content with exception of formulation 4 that had relatively good quality due to TPC content with magnitude of 7.2 x 10
5
coloniesgram. All treatments at 30, 42 and 48 hours storage time had TPC values of 10
6
coloniesgram, 10
7
coloniesgram and 10
8
to 10
9
coloniesigram, respectively.The effect of formulation, temperature and shelf life on the change of TPC of pempek during storage was described by the following model :
Y = 1,528 – 0,096 X
1
+ 0,035 X
2
+ 0,092 X
3
R
2
= 0,989......................................................... 7 The numbers of aerobic microorganism on food material can be determined from its TPC concentration
in which the numbers of bacteria, fungi and yeast were increased during storage. Microbes growth during storage was due to availability of organic components especially protein, carbohydrate and water within
pempek. Microbes growth within food will produce several metabolites or byproduct which are associated with deterioration characteristics. Based on the standard from Dirjen POM No.03726BSKVII1989, the
maximum limit for microbes or TPC within food, fish and fish products was 10
6
coloniesgram Dirjen POM, 1989. The maximum limit of microbes number for products made of fresh fish was 10
6
coloniesgram and it is still organoleptically acceptable up to 10
8
coloniesgram although mucous had already been developed on products Kaba, 2006.,Amegovu
et al
, 2012.
4. Conclusion
