Development of Reduced Sodium Shrimp Paste from Shrimp Head

Abstract

A significantly decreased of natural resources has been reported every year until now. This problem also including the decreasing of Mesopodopsis, a main raw material to produce tradition shrimp paste, Kapi which is a key ingredient in various Thai dishes. In contrast with decreasing of Mesopodopsis, most of by-product from frozen shrimp processing industry such as head, shell and tail were increased and still needed to utilize. However, shrimp head abundance with unsaturated fatty acid that susceptible to lipid oxidation. In addition, consumption of high sodium food as such Kapi can cause various health problems especially hypertension. Recently, there are many reports about hypertension due to high sodium consumption with low potassium intake. Therefore, this experiment was designed to meet 3 main objectives: The first aim was to produce the reduced sodium shrimp head paste. Shrimp head was mixed with salt as ratio shrimp head 12, 14 and 16 per 1 salt. After fermentation for 90 d, chemical, physical, microbiological and sensory quality of all treatments were determined. The result found that water activity (aw) decreased in all treatments. The highest total volatile bases nitrogen (TVB-N), trimethylamine (TMA) thiobarbituric acid reactive substances (TBARS) and degree of hydrolysis (DH)were found in treatment with the highest shrimp head proportion (16:1). There was no histamine detected while indole was significantly increased. After fermentation for 90 d, significantly decreased of total viable count (TVC) and lactic acid bacteria (LAB) were found in all treatments with no pathogenic microorganisms detected. Although, no significantly difference in sensory score (approximately 6) was found, treatment with shrimp 12 per 1 salt seemed to have higher score in all attribute than other treatments which was lower than that of commercial shrimp paste with approximately 7.5 in 9. To prevent lipid oxidation in shrimp head paste, garlic was mixed at 0%, 3% and 5% and determined the shrimp head paste quality as mentioned the first part. The resulted show that aw reduced in all treatments while pH seemed to kept constant. In addition, TVB-N, TMA, TBARS and DH significantly increased in all treatments. When compared to control sample (without garlic), lipid oxidation of treatment with addition of garlic at 3% and 5% was retarded. There was no histamine detected while indole was significantly increased. TVC decreased to around 2.54 log CFU/g while LAB decreased to 1 log CFU/g in all treatments. Pathogenic microorganisms were not found in all treatments after fermentations for 90 days. Sensory score of all treatments were approximately 6 which was still lower than that of commercial shrimp paste with approximately 7.5 in 9. The final aimed (3) was to reduce more sodium chloride by replacing with potassium chloride at 0%, 30% and 50%. After 90 d, reduction of aw and increment of pH were found in all treatments. In addition, a significantly increased of TVB-N, TMA, TBARS and DH were found in all treatments. TVC decreased from 5.90 log CFU/g to around 2.95 log CFU/g while LAB decreased from 5.71 log CFU/g to 1 log CFU/g in all treatments. Pathogenic microorganisms were not found in all treatments after fermentations for 90 d. Based on production regulation on chemical and microbiological qualities of shrimp paste, shrimp head paste was considered as safe for consumption. Bitter taste was not detected in any treatment with added KCl. ACE Inhibition (%) of shrimp head (S1) and shrimp head paste (S2 NaCl 7.69%; S3 6.36% KCl 2.73%; S4 NaCl 4.55% KCl 4.55%) at 1 mg/ml were 36.21±0.88%, 53.47±2.81%, 51.14±3.50% and 45.80±3.45%, respectively while ACE Inhibition (%) of captopril at 5 nM, 10 nM and 20 nM were 29.39±2.18%, 36.00±4.34% and 48.70±1.41%, respectively. Sensory score of all treatments were approximately 6 which lower than that of commercial shrimp paste with approximately 7.5 in 9. In summary indicated that shrimp head can be used to produce shrimp head paste with physical, chemical and microbiological qualities comparable to commercial shrimp paste. However, improvement of sensory quality by using properly machine or enzyme to reduce size of shrimp head and adding sugar to improve taste is required in further work. Addition of garlic at 3% and 5% seemed to retard lipid oxidation determined by TBARS assay and did not have any negative effect on other qualities of shrimp paste. Based on physical, chemical, microbiological and sensory qualities, reduce sodium by replacement with KCl at 50% was comparable with 0% KCl shrimp head paste. In addition, no bitter taste was detected in shrimp head paste replacement NaCl with KCl up to 50%. Reduction of hypertension determined by ACE inhibition of shrimp head paste made from 50% KCl substitution was similar value to shrimp head paste made from 100% NaCl.