Md. Farhan Tazim
Marine Fisheries Survey Management Unit, Department of Fisheries, Agrabad, Chattogram, Bangladesh.
Md. Nazrul Islam
Department of Fisheries Technology, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh, Bangladesh.
Afrin Sultana
Department of Fisheries Technology, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh, Bangladesh.
Mohammed Rashed Parvej
Marine Fisheries Survey Management Unit, Department of Fisheries, Agrabad, Chattogram, Bangladesh.
Al Mamun
Marine Fisheries Survey Management Unit, Department of Fisheries, Agrabad, Chattogram, Bangladesh.
Md. Abdullah Al-Mamun
College of Fisheries, Ocean University of China, Qingdao 266003, China.
Amino acid profile; Fermentation; Fish feed supplement; Lactic acid bacteria
Mymensingh district in Bangladesh
Quality and Nutrition
Fish wastes such as heads, bones, viscera, fins, tails produced in large quantities during the filleting process were used as protein substrates for this experiment. Substrates were collected from the different freshwater fish markets of Mymensingh town. Substrate samples were then sorted for the removal of fish scales and all other unnecessary materials. Then the samples were kept at freezing temperature (-200C) for silage preparation later on. Frozen samples (fish entrails) were thawed at room temperature. Then the samples were chopped and minced using a sharp knife. Minced samples were then weighed and divided equally into 4 cylindrical containers with a radius of 7 cm and a height of 25cm. The additional carbohydrate sources (molasses) along with various fermentation starters were added into different compositions into the three containers for fermented silage preparation. On the other hand, 3% formic acid was added into 97% minced samples for acid silage preparation. These three fermented silage treatments and one acid silage treatment were designated as FS-1, FS-2, FS-3, and AS-1 respectively. Then all the containers were sealed and kept at room temperature for fermentation. During the fermentation period pH, lactic acid bacterial growth (LAB), and non-protein nitrogen concentration (NPN) were estimated at regular intervals. On the 6th day of fermentation, all the silages pH was measured around 4 which is desirable for the fermentation. NPN content was determined by the trichloroacetic acid (TCA) precipitation technique [4]. For the isolation of Lactobacillus fresh milk, yogurt, and fish sauce were used as source samples. One milliliter of each liquid product was inoculated into MRS (de Man Rogosa Sharpe) broth (Oxoid) of various pH values (6.2, and 4.3). The broths were incubated at 30oC for 24 hours. Isolated colonies were obtained by streaking on MRS agar (Oxoid) plates and the plates were incubated anaerobically at 30oC for 48 hours. Predominant and typical colonies were picked from cultures isolated from the broth of pH 3.5.
All the isolates were then tested for gram staining, microscopic morphology, spore formation, Hugh and Leifson’s Oxidative/Fermentative test (O/F test), motility, and catalase test, respectively by the method described by Ismail and Goyal. The identified isolates were found at low pH MRS broth, anaerobic, gram-positive, rod-shaped, endospore negative, fermentative in O/F test, non-motile and catalase-negative. Selected identified isolates were then inoculated into the MRS broth for fermented starter production and incubated at 35oC for 24 hours. Isolates were incubated until the Lactobacillus growth reached 108-9 bacteria/ml in the broth. Proximate composition analysis for moisture, crude protein, lipid, and ash contents were carried out according to the methods of AOAC. Therefore, Moisture content was determined by a thermostat oven (Gallenkamp, Hotbox Model Ovb) at 105oC for 24 hours until a constant weight was obtained. Micro-Kjeldahl method was used to estimate the total nitrogen content, then crude protein was identified by multiplying 6.25 the conversion factor, methods described by Zotti, lipid content was determined by solvent extraction method using a ground joint Soxhlet Apparatus (AOAC, 1990), ash content was estimated by heating the sample in a muffle furnace at a temperature of 550oC, crude fiber was estimated by the loss on ignition of dried lipid-free deposits after digestion with 1.25% H2S04 and 1.25% NaOH by the method applied by Asowata. Samples were quantified based on total nitrogen content by hydrolyzing with 6N HCL in an evacuated heat-sealed glass hydrolysis ampoule over an aluminum block heater at 110oC for 24 hours as the methodology followed by Moore and Stein. Amino acids were determined by Liquid Chromatography using a cationic exchange column to retain the amino acids from the sample then the column was switched in-line with gradient pump and separator column by the methods described by Zendik. All the data obtained from this experiment were analyzed in triplicates in each treatment. Results of triplicates were analyzed using single-factor ANOVA to identify the significant differences at P<0.05 followed by Tukey-HSD. The data were illustrated as mean ± standard deviation. Graphical representation of the data was performed by the software Sigmaplot 14.
Asian Journal of Fisheries and Aquatic Research- 13(4): 1-9, 2021
Journal