No abstract

Joruk is a traditional fishery product made by spontaneous fermentation process using lactic acid bacteria by salting method, followed by fermentation process. Hydrolysis of proteins with the pepsin and a combination of pepsin and trypsin enzymes by in vitro can produce bioactive peptides. The aims of this study were to investigate the change of soluble protein and lactic acid content in oci fish joruk (Rastrelliger kanagurta) and to determine the influence of the enzyme hydrolysis on the antioxidant activity of joruk. The raw material used in this highest study was the oci fish obtained from Gorontalo, Indonesia. The produced joruk was added with the concentration of palm sugar 10%, 20% and 30% then fermented for 8 days, 10 days and 12 days. Protein hydrolysis using the pepsin enzyme and a combination of pepsin and trypsin enzyme. The results showed that the addition of palm sugar and fermentation time can reduce soluble protein and increase the lactic acid content. The highest antioxidant activity was found in joruk hydrolysate that hydrolyzed by pepsin enzyme with the addition of 30% palm sugar and 12 days fermentation, with a value of 5.28%.

Hypertension is one of the major global health issues worldwide. One of the methods can be used to treat this disease is by inhibiting the activity of angiotensin converting enzyme, an enzyme that controls the regulation of arterial blood pressure and cardiac output. Bekasam is one of the traditional fermented food made from freshwater fish (oci, Rastreliger kanaguria) with the addition of carbohydrate sources (variation concentration of palm sugar i.e. 10%; 20%; and 30%). The objective of this research was to investigate the effect of palm sugar concentration to the ACE inhibitor activity of bekasam after digestive enzyme degradation by trypsin. Hydrolysis process was evaluated by determination of the concentration of soluble protein and the degree of hydrolysis (DH) after treatment and the ACE-inhibitory (ACEI) effect was determined by spectrophotometry method. Compared to the control without trypsin treatment (5.00±0.10 mg/ml), the concentration of soluble protein (mg/ml) of bekasam was increased after trypsin hydrolysis to 16.57±0.55 at 10% of added palm sugar and then decreased to 15.38±0.18 and 10.85±0.28, at 20 and 30% of added palm sugar respectively. The degree of hydrolysis was 21.3±0.3%, 19.7±0.5% and 15.3±0.4%, for 10, 20 and 30% of palm sugar, respectively. The ACE-inhibitory activity was 87.39±0.01, 84.52±0.84, and 77.68±0.63%, for 10, 20 and 30% of added palm sugar, respectively. The results showed that the concentration of palm sugar affects the soluble protein content, degree of hydrolysis and ACEI activity after trypsin hydrolysis with the optimum sugar concentration was 10%.

Milkfish that have been seasoned with some spices then cooked by a high -cooker produced a fish product which has soft spines and bones. The product which has a local name bandeng presto has been popular in Indonesia due to the product is tasty and it is easier to be consumed directly after it is prepared as a dish. The storage life of bandeng presto is relatively short, which is due to deterioration process by microbes after processing. Consequently, this condition can retard the products distribution. The aims of the research are to understand is there any significant influence of differing the drying time (0 hours and 4 hours) of milkfish cooked by a high-pressure cooker by using an electric oven (50oC) and storage period at room temperature (5 days) and also to find out which treatment produce the best product quality. The results showed that the treatment of differing the drying period gave a highly significant influence (P <0.01) on the sensory value and the moisture content but did not gave significant influence (P >0.05) on the number of bacteria colonies. The length of storage period gave a highly significant influence (P <0.01) on the sensory value between the products which were dried for 4 hours and without drying treatment but only the drying process for 4 hours gave a highly significant influence (P <0.01) on the moisture content, the water activity and the number of bacteria colonies. The quality of the products that were dried for 4 hours were better and their storage life can reach up to 3 days compared to the products that were not dried.Keywords: Milkfish, high pressure cooker, drying, oven, quality, storage life