The production of soluble fish protein solution for use in fish sauce manufacture II. The use of acids at ambient temperature

Abstract

When batches of Ikanbilis were acidified using hydrochloric acid to pH 2.0-3.5 at 30°C, the rate and extent of hydrolysis of the fish protein and the rate of formation of supernatant liquor were increased.The effect of pH and salt concentration was invqtigated. Although the presence of salt generally decreased the extent of proteolysis, it made the mixtures easier to filter. The optimum conditions were either p H 2.0 and 10% salt (w/w) or pH 3.0 and 15% salt (w/w). The extent of fish protein hydrolysed was comparable to the natural fermentation and the concentrations and distribution of soluble nitrogen were very similar to those obtained in the traditionally produced sauces. This liquor was produced within 6 days. The natural fermentation takes 4-9 months.The use of formic acid was investigated and showed no particular advantage.When the pH of the acid ensiled mixtures was adjusted above 4.2, calcium phosphate precipitated; this was removed by filtration. The effect of adding alkaline ensiled fish to acid ensiled fish mixtures (the p H of which had been re-adjusted) was investigated. The amount of insoluble protein hydrolysed increased to a limited extent.As the solutions produced by acid ensilation had very little aroma or taste but had a high soluble nitrogen content, they could be used to add to traditionally prepared fish sauce in order to increase the net volume which would increase the rate of production.

Advances in Seafood Byproducts: 2002 Conference Proceedings

“…Pepsins are significantly inhibited by salt concentrations over 5%, but a low salt content allows for spoilage (Gildberg et al 1984). No apparent spoilage occurred with salt concentrations of 10% or more (Beddows and Ardeshir 1979). Reduction of salt concentration did not increase the rate of hydrolysis and percent of protein conversion when bromelain was used (Beddows et al 1976).…”

“…Reduction of salt concentration did not increase the rate of hydrolysis and percent of protein conversion when bromelain was used (Beddows et al 1976). The addition of acid at an ambient temperature promotes the activities of the proteolytic enzymes originating from fish (Beddows and Ardeshir 1979). Experiments with fish silage have shown that pH 4 gives the optimum speed of autolysis (Gildberg et al 1984).…”

“…Use of low pH increased the rate and extent of proteolysis of ikanbilis (Stolephorus sp. ), with optimum conditions either pH 2.0 with 10% salt or pH 3.0 with 15% salt w/w (Beddows and Ardeshir 1979). Gildberg et al (1984) concluded that acidification improves autolysis only at low salt concentration (5%, w/w).…”