Reduced Washing Cycle for Sustainable Mackerel (Rastrelliger kanagurta) Surimi Production: Evaluation of Bio-Physico-Chemical, Rheological, and Gel-Forming Properties

Although dark muscle is currently the most important obstacle in marketing high-quality Indian mackerel (Rastrelliger kanagurta) surimi, reducing washing remains a challenge for long-term surimi production from this species. Herein, the impact of washing cycles (one (W1), two (W2), and three (W3) cycles) with a 1:3 mince to water ratio on the bio-physico-chemical properties, rheology, and gelling ability of mackerel surimi was evaluated. The yield, Ca2+-ATPase activity, TCA-soluble peptide, and myoglobin contents of surimi decreased as the number of washing cycles increased, while lipid removal, reactive SH content, and surface hydrophobicity of surimi increased. Surimi generated by W2 and W3 provided the same rheological patterns and Fourier-transform infrared spectroscopy (FTIR) spectra as unwashed mince, with the highest gel strength and whiteness, as well as the lowest expressible drip, thiobarbituric acid reactive substances (TBARS), and fishy odor. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated the presence of polymerized proteins stabilized by disulfide and other interactions. Using a scanning electron microscope, several concentrated dense areas and distributed pores generated by myofibrillar proteins gel networks were found. Surimi from W2 and W3 appeared to be of similar overall quality, however W2 had a larger yield. As a result of the evaluation of bio-physico-chemical, rheological, and gel-forming capabilities, as well as product yield, W2 may be the best option for producing high-quality surimi from Indian mackerel in a sustainable manner.

Biomedical applications of fish gut associated Streptomyces maritimus IM20 isolated from Rastrelliger kanagurta (Indian mackerel)

The biomedical potential of fish gut-associated actinobacteria isolated from the marine fish Rastrelliger kanagurta (Indian mackerel) was investigated. The actinobacterial strain IM20 was isolated from the fish gut by using Kusters agar medium prepared with 50% sea water. Based on their phenotypic and molecular characteristics, strain IM20 was identified as Streptomyces maritimus. The bioactive metabolites produced from the strain IM20 by agar surface fermentation and ethyl acetate extraction were tested for in vitro antimicrobial, antiquorum sensing , anti-biofilm, anti TB, anti-oxidant and anti-cancer activity. The MIC value of ethyl acetate extract (EAE) of IM20 was found to be 16 μg ml−1 against S. aureus and E. coli. In quorum sensing inhibition assay, the extract showed violacein inhibition upto 87% at 512 μg ml−1 concentration when tested by pigment inhibition assay using C. violaceum MTCC 2656. The results of in vitro assays revealed that the ethyl acetate extract of IM-20 (EAE-IM20) showed 75%, 83% and 72% inhibition against Mycobacterium tuberculosis H37Rv, M. tuberculosis (SHRE sensitive) and multi drug resistant (MDR) M tuberculosis respectively at 500 μg ml−1 concentration. In DPPH assay, 71% radical scavenging activity was exhibited by the EAE-IM20 at 250 μg ml−1. In MTT assay, EAEIM20 exhibited 74.29±2.01% inhibition on breast cancer cell line MCF7 (250 μg ml−1). This study broadly determines that the fish associated actinobacteria is a prolific place for diverse multifunctional bioactive compounds for the development of medically important unique drugs.

A study on ectoparasites in Indian Mackerel, Rastrelliger kanagurta (Cuvier, 1817) of Thiruvananthapuram coast, South India

Parasitic infestation in marine fish requires urgent attention, especially those that infect economically important fishes, which affect their aesthetic quality and palatability. Ectoparasites in Indian Mackerel, Rastrelliger kanagurta (Cuvier, 1817), have not been studied well. Morphological and seasonal study of ectoparasites in R. kanagurta from the Thiruvananthapuram coast was conducted during March-August 2018. The study investigated three parasitic groups: Trichodinids, Digenean cysts (Centrocestus Looss, 1899), and Cymothoids (Norileca indica Milne Edwards, 1840 and Nerocila phaiopleura Bleeker, 1857) from R. kanagurta during the present study. Of the 240 fishes examined, the Trichodinids and digeneans showed 100% prevalence on the gill samples. Seasons had no significant effect on trichodinids and digeneans prevalence. However, parasitic Cmothoids fluctuated significantly according to the season. They showed greater prevalence during the pre-monsoon (45%) and least in monsoon (25%) due to environmental parameters like rainfall, salinity, and temperature. Trichodinids parasitized gills of R. kanagurta showed increased mucus production, paleness in the gills, and multifocal whitish areas. The Cymothoid infested fish showed lesions with the erosion of the epidermis and underlying dermis at the site of attachment. The noticeable changes were observed in the gill epithelium due to the encystment of digeneans. The Trichodinid ciliates and Heterophyid digenean cysts (Centrocestus Looss, 1899) are reported for the first time in R. kanagurta.

Effectiveness of fermented cabbage to increase storage time of Indian mackerel (Rastrelliger sp.) at room temperature

Makarel India adalah ikan air laut yang umum dikonsumsi. Keunggulan ikan tenggiri adalah memiliki cita rasa yang enak, harga yang terjangkau, dan dapat diolah menjadi berbagai macam masakan. Kelemahan dari ikan kembung India adalah mudah untuk mengalami penurunan kualitas. Salah satu cara untuk memperpendek umur simpan adalah dengan penambahan es. Cara pengawetan lainnya adalah dengan memanfaatkan bakteri asam laktat hasil fermentasi kubis. Kubis digunakan sebagai bahan starter fermentasi karena memiliki harga yang terjangkau dan mudah didapatkan. Tujuan penelitian ini adalah untuk mengetahui umur simpan ikan tenggiri yang direndam menggunakan larutan fermentasi kubis dengan lama waktu 1 jam, 2 jam, dan 3 jam. Sampel ikan kembung India berasal dari pasar ikan. Ikan dicuci menggunakan air bersih, kemudian direndam menggunakan larutan fermentasi kubis dengan lama waktu perendaman 1 jam, 2 jam, dan 3 jam. Parameter yang diamati adalah kenampakan mata, insang, lendir pada permukaan tubuh, daging, bau, dan tekstur. Hasil penelitian menunjukkan umur simpan ikan tenggiri pada suhu ruang adalah 11 jam (untuk kontrol), sedangkan umur simpan ikan tenggiri direndam selama 1 jam, 2 jam, dan 3 jam adalah 14 jam. Pengujian menggunakan Anova menunjukkan nilai signifikan sebesar 0,351. Artinya lama perendaman menggunakan larutan fermentasi kubis tidak mempengaruhi umur simpan ikan tenggiri. Hasil penelitian menunjukkan umur simpan ikan tenggiri pada suhu ruang adalah 11 jam (untuk kontrol), sedangkan umur simpan ikan tenggiri direndam selama 1 jam, 2 jam, dan 3 jam adalah 14 jam. Pengujian menggunakan Anova menunjukkan nilai signifikan sebesar 0,351. Artinya lama perendaman menggunakan larutan fermentasi kubis tidak mempengaruhi umur simpan ikan tenggiri. Hasil penelitian menunjukkan umur simpan ikan tenggiri pada suhu ruang adalah 11 jam (untuk kontrol), sedangkan umur simpan ikan tenggiri direndam selama 1 jam, 2 jam, dan 3 jam adalah 14 jam. Pengujian menggunakan Anova menunjukkan nilai signifikan sebesar 0,351. Artinya lama perendaman menggunakan larutan fermentasi kubis tidak mempengaruhi umur simpan ikan tenggiri.