Technological Studies On The Effect of Some Natural Additives On Fish Products

Salted sardine fish (Sardinella gibbosa) was prepared according to the traditional methods used in the Mediterranean countries with added 0.0, 0.1 and 0.2 % of pepsin enzyme and salted with 15 % NaCl. The changes in organoleptic quality and proteolytic degradation during fermentation at (37°C  1°C) were evaluated.The obtained results revealed that addition of pepsin enzyme affected the physic-chemical properties of salted sardine during fermentation. However, sardine treated with pepsin showed the highest concentration of nitrogen fractions and free amino acids. Moreover, the addition of proteolytic enzymes improved the sensory evaluation and accelerated the proteolysis of protein muscles in salted sardine.Fish sauce fermentation is widely used in Southeast Asia as a means of preservation and producing valued added products from underutilized fish species. The physicochemical and protein breakdown and the sensory characteristics of Sardine fish sauces containing 15 and 20% of salt and treated with Bromelain enzyme were evaluated during fermentation at 37°C  1°C for 180 days.Results showed that supplementation with Bromelain increased significantly the rate of proteolysis and accelerated the fermentation time period. Sardine fish sauces containing 15 and 20% of salt and treated with 0.15 and 0.3% proteolytic enzyme Bromelain contained higher concentrations of Formol nitrogen, VBN-N and amino nitrogen in the final fish sauces during fermentation compared to control sauce.Supplementation sardine fish sauce containing 15% salt and treated with 0.3% of Bromelain showed the highest concentration of nitrogenous compounds. However, the levels of these compounds in sardine sauces containing 20% salt and treated with 0.3% of Bromelain were lower than in sardine sauces containing 15% salt and treated with 0.3% of Bromelain during fermentation.Results of sensory evaluation indicated that sardine fish sauce treated with 0.15 and 0.30% of Bromelain enzyme and containing both 15 and 20% salt after 90 days of fermentation showed the best organoleptic properties (brown colour, typical aroma and flavour of sardine sauce among enzyme supplemented sauces).The total bacterial counts of sardine sauce treated with Bromelain enzyme were slightly lower than that observed in sardine sauce without enzyme (natural fermentation).Catfish burgers were prepared by using minced catfish filet mixed with different levels of soy protein curd. Quality changes of the resultant catfish burgers during storage at 4°C were investigated. Catfish burgers containing 20% soy protein curd were found to be the most organoleptically accepted formulation within acceptable limits during cold storage at 4°C for 7 days.Moreover, the sensory evaluation showed that fried catfish burgers made from catfish containing 20 % of soy protein curd had the highest organoleptic score points.The effects of rosemary at different levels (0.0, 0.4 and 0.6%) on the quality of catfish burgers containing 20% soya protein curd in terms of sensory, biochemical (Trimethyl amine TMA, total volatile basic nitrogen TVBN, Thiobarbituric acid TBA, peroxide value PV and free fatty acids FFA and total viable counts) were also evaluated. The catfish burgers samples were stored at 4± 1°C over the storage period of 18 days.The obtained results showed that the use of rosemary improved the sensory quality of catfish burgers, most preferably catfish burgers treated with 0.6 % of rosemary. Biochemical analysis showed that the use of 0.6 % rosemary was found to be the most effective in controlling the rate of lipid Oxidation and prolonged the shelf life of the product till the fifteenth day of cold storage.