A Group of Researchers of IPB Utilized Ultrasonic Waves to Preserve Fish Fillet
A fish fillet, from the French word filet meaning a thread or strip, is the flesh of a fish which has been cut or sliced away from the bone by cutting lengthwise along one side of the fish parallel to the backbone. This fish is much processed into a typical food sakura country or Japan such as sushi or sashimi. Not only popular in Japan alone, this processed fish products are quite popular in Indonesia, especially for young generations. Not surprisingly, now th Japanese-style dining place has mushroomed in Indonesia, especially in big cities like Jakarta.
A group of researchers of Bogor Agricultural University (IPB) consisted of Ruddy Suwandi, Agoes Mardiono Jacoeb and Maya Sofia, carried the research program on "Aplikasi Gelombang Ultrasonik sebagai Alternatif untuk Mempertahankan Kesegaran Fillet Ikan Nila (Application of Ultrasonic Waves as an Alternative to Maintain Freshness of Tilapia Fish Fillet)".
"The food industry, in fisheries and aquaculture sector, requires easy and efficient technology to be applied in its use, for example fish fillets. The nature of this fish fillet is easily deteriorated in its quality, therefore it requires alternative technology to maintain the freshness of the product. Accordingly, ultrasonic wave technology is created, "said Ruddy Suwandi.
The researchers who were from the Department of Aquatic Product Technology (THP) utilized tilapia (Oreichromis niloticus) weights 200-250 grams each. The instrument used is an oscilloscope (Model GOS-622G, 20Mhz) and Funtion Generator (Model BK Precision 4011A, 5 MHz) to perform ultrasonic wave sonication.
Several stages of testing were performed after the fillet process, they were then tested according to the fish freshness parameter (organoleptic, pH, TVB, TPC), storage analysis and histology test wherein sonication was carried out for 6.9 and 12 minutes.
The organoleptic results after 4 and 5 hours of the sonication processes showed that the appearance of fillets were decreased. The meat is whitish-greenish and less brilliant and produced scent odor (a slight odor of ammonia and an additional odor) and less elastic texture. This decreased quality was due to the destruction of proteins by microbial activity.
Acidity or pH of fishes that were not accessed by ultrasonic waves become lower in value or more acid compared to those affected by sonication. Then for the Total Volatile Base (TVB) value does not look very different between the two. Total Plate Count test results on sonication results show different values when compared with those not. This shows the difference in the number of microbes. Especially the amount of microbes in fish without sonication.
The histologic result of the appearance of the structure of the meat tissue showed that fish without sonication had a more compact structure compared to those accessed by the sonication. As sonication can affect the structure of the meat, they become more watery.
"Ultrasonic waves are quite effective in inhibiting microbial growth. However, when they are suitable environment and temperature to multiply, then the microbes can grow optimally as well, "he added. (Wied)
