The Use of Water Seal Fermentor in Fish Fermentation of Bekasam Basuni Hamzah

Fermentation of fresh water fish using water seal fermentor was studied. In the experiment, 3 concentration of salt were applied, namely, 2, 4 and 6%, respectively. The sample of products was observed every week until week 4. The result showed that the lowest final pH was at salt concentration of 4%. At the end of fermentation at concentration of 4%, Lactobacillus plantarum had been predominantly to grow. However, less salt concentration tended to be less selective of Lactic Acid Bacteria. Probably other than lactic acid bacteria also had been grown, inhibiting the growth of Lactobacillus plantarum. At the concentration of 6% there was predominantly growth of Leuconostos mesentroides and less Lactobacillus plantarum had been grown. At low pH such as at salt concentration of 4%, the pH value was 4.12 will be much more preserved comparing to other two salt concentrations. The use of water seal fermentor would keep the temperature about 18°C. The temperature which lower than ambient temperature along with certain salt concentration would be the best way to select LAB microorganisms.


INTRODUCTION
In the province of South Sumatera, Indonesia much of the seasonally available fish is preserved by fermentation and fermented foods are consumed daily.Eating large quantity of rice is a cheap source of vegetable protein, amino acids and energy.Therefore, a vital individual foodstuff is either a salty side dish or a condiment that facilitates rice consumption.Fermented products are well suited for this, since they are simple to produce and cook, have a long shelf life (Caplice and Fitzgerald, 1999).It is no coincidence that the the region where fermented fish products are consumed overlap with the region of rice cultivation (Essuman, 1992).
South Sumatera province has various indigenous traditional fermented food products such as tempoyak, rusip, pedah and bekasam.Bekasam is a fermented fish product using fresh water fishes as main material.Cooked rice functions as substrate for the microorganisms, whereas salt is used as selective agent.The anaerobic fermentation takes place, traditionally, at least for one week in ambient temperature (Kimizuka et al., 1992).The resulting bekasam has the following superior characteristics, including excellent nutritive values, typical and pleasant sensory properties and safe to consume (Rahayu, 2010).
In the fact, bekasam is consumed by limited people in a few districs in South Sumatera province.Its surface is still smeared by rice rest, gives unhygienic impression.Consequently, the total acceptance of bekasam by consumer decreases.Traditional, local trader put bekasam fishes in open containers.This explains why contamination by molds occurred in high frequencies and shortened shelf life of bekasam.
Several investigations concerning microbiological aspects of bekasam have been carried out.A number of 28 Lactic Acid Bacteria (LAB) isolates were collected, purified and screened as well as partially, phenotipically identified.They were characterized by cell morphologies (cocci or rod), Gram positive and catalase-negative.A differential analysis suggested 5 genera of predominant LAB namely Lactobacillus, Streptococcus, Pediococcus, Enterococcus and Tetragenococcus (Wijaya et al., 2008).
The term Bekasam is used here to describe the product of fresh water that are processed with salt to cause fermentation and thereby to prevent putrefaction.Although the same phenomenon occurs with salted fish product.In the fermentation of Bekasam, fresh water fish is used and addition of some salt usually about 10%, the addition also of boiled rice, the put in the big dish made from dried mud earth.In this research, the fermentation of fish using water seal fermentor, instead.

RESULTS AND DISCUSSION
The result of this study is shown in Table 1.The data showed that all three salt concentration the pH decreases as the fermentation continued until week 4. Salt concentration of 2% had pH of 6.82 (week 1), 6.01 (week 2), 5, 91 (week 3) and 5.62 (week 4).At salt concentration of 4% had pH of 6.15 (week 1), 5.43 (week 2), 4.12 (week 3) and 5.62 (week 4).And at salt concentration of 6% had pH of 6.05 (week 1), 5.65 (week 2), 5.34 (week 3) and 5.03 (week 4).The lowest final pH was at salt concentration of 4%.At the end of fermentation at concentration of 4%, Lactobacillus plantarum had been predominantly to grow.However, less salt concentration tended to be less selective of Lactic acid bacteria.Probably other than lactic acid bacteria also had been grown, inhibiting the growth of Lactobacillus plantarum.At the concentration of 6% there was predominantly growth of Leuconostos mesentroides and less Lactobacillus plantarum had been grown.Ay low pH such as at salt concentration of 4%, the pH value was 4.12 will be much more preserved comparing to other two salt concentrations.The use of water seal fermentor would keep the temperature about 18°C.The temperature which lower than ambient temperature along with certain salt concentration would be the best way to select LAB microorganisms.

CONCLUSION
The use of water seal fermentor along with the addition of salt concentration of 4% had been the best way to preserve fish fermentation of Bekasam at least for 4 weeks with the final pH of 4.12.