Effects of the addition of spleen of skipjack tuna (Katsuwonus pelamis) on the liquefaction and characteristics of fish sauce made from sardine (Sardinella gibbosa)

Abstract

The effects of skipjack tuna (Katsuwonus pelamis) spleen addition at various levels (0, 10 and 20%) on the liquefaction and characteristics of sardine fish sauce produced with different salt concentrations (15, 20 and 25%) were monitored during fermentation of 180 days. Fish sauce prepared from sardine with spleen supplementation contained greater total nitrogen, amino nitrogen, formaldehyde nitrogen, ammonia nitrogen content, compared to those without spleen addition throughout the fermentation. The rate of liquefaction was dependent upon the amount of spleen added. Reduction of salt content accelerated the hydrolysis of fish protein during fermentation. The liquefaction rate of the lower salt treated samples was generally faster than those treated with higher salt content. Among all treatments, sardine added with 25% spleen and 15% salt exhibited the greatest protein hydrolysis, particularly at early stages, suggesting the combination effects of autolysis and spleen proteinase. The greater liquefaction was coincidental with the development of browning as well as the increase in redness of liquid formed. Acceptability test revealed that the samples were different in color, aroma, taste as well as overall acceptance (p<0.05). Fish sauce samples containing 20% salt without and with 10% spleen addition had the similar acceptability with commercial fish sauce. Therefore, addition of spleen as well as salt reduction can accelerate the liquefaction of sardine for fish sauce production.

Changes in antioxidant activities and physicochemical properties of Kapi, a fermented shrimp paste, during fermentation

“…The results suggested that the fermentation of Kapi resulted in considerable increases in amino acids. Similar results were also found during hydrolysis of fish and fish products including minced mackerel fermented with LAB (Yin et al 2005), and fish viscera during fish sauce fermentation (Klomklao et al 2006). Enzymatic fermentation of small shrimp mediated by indigenous proteinases yields the short chain peptide and free amino acid (Steinkraus 2002).…”

“…Nonenzymatic browning of samples was determined by measuring melanoidin pigment formation following the method of Klomklao et al (2006) with a slight modification. One gram of sample was mixed with 50 ml of 50 % (v/v) ethanol and the mixture was stirred for 1 h at 25°C.…”

“…Formaldehyde nitrogen content has been used to measure the degree of protein hydrolysis (Klomklao et al 2006). Generally, the increases in formal nitrogen content were obtained with increasing fermentation time of fish fermented products (Tungkawachara et al 2003;Klomklao et al 2006;Jiang et al 2007;Xu et al 2008). The results indicated that the degradation of protein took place continuously during fermentation as evidenced by the increase in formaldehyde nitrogen content.…”

“…Melanoidin generated during fermentation might play an important role in browning (Zamora and Hidalgo 2005). Maillard reaction was found to be responsible for the brown colour in fish sauce (Tungkawachara et al 2003;Klomklao et al 2006). Therefore, prolonged fermentation resulted in substantial increases in browning intensity, thereby influencing the colour development in Kapi.…”

Untitled

“…KA had the higher formal nitrogen content (14.92 mg N/g sample), compared with KM (11.76 mg N/g sample) (P<0.05), suggesting the greater cleavage of peptides caused by endogenous or microbial proteases in the former. Generally, the formal nitrogen content has been used to indicate the degree of protein hydrolysis (Klomklao et al, 2006). There was no difference in ammonia nitrogen content between these two samples (P>0.05).…”