Characterization of the Flavor Profile of Bigeye Tuna Slices Treated by Cold Plasma Using E-Nose and GC-IMS

To avoid heat, treatment induces numerous physicochemical changes under severe conditions in the tuna, cold plasma (CP), as a non-thermal technology, possess objective potential on tuna processing. The effect of cold plasma on the volatile flavor compounds of bigeye tuna (Thunnus obesus) sashimi has been evaluated using electronic nose (E-nose) and gas chromatography-ion mobility spectrometry (GC-IMS). GC–IMS results revealed a total of 33 volatile compounds in tuna slices. The effect of CP treatment on tuna flavor was not significant, furthermore CP could protect volatile freshness compounds such as 1-hexanol. Principal component analysis (PCA) of the E-nose and GC–IMS results could effectively differentiate the effect of storage to tuna sashimi. There was a high correlation between the E-nose and GC–IMS results, providing a theoretical basis for establishing the flavor fingerprint of tuna sashimi.

Comparison of Physicochemical Changes and Water Migration of Acinetobacter johnsonii, Shewanella putrefaciens, and Cocultures From Spoiled Bigeye Tuna (Thunnus obesus) During Cold Storage

This study investigates the physicochemical changes and water migration of Acinetobacter johnsonii (A), Shewanella putrefaciens (S), and cocultured A. johnsonii and S. putrefaciens (AS) inoculated into bigeye tuna during cold storage. The physicochemical indexes [fluorescence ratio (FR), total volatile base nitrogen (TVB-N), thiobarbituric acid (TBA), trimethylamine (TMA), peroxide value (POV), and pH] of bigeye tuna increased cold storage. A significant decrease in trapped water was found in the AS samples, and direct monitoring of the water dynamics was provided by low-field nuclear magnetic resonance. Samples inoculated with A. johnsonii and S. putrefaciens also induced the degradation of myofibrillar proteins and weakness of some Z-lines and M-lines. Higher values of physicochemical indexes and water dynamics were shown in the coculture of S. putrefaciens and A. johnsonii than in the other groups. Therefore, this paper reveals that the coculture of A. johnsonii and S. putrefaciens resulted in a bigeye tuna that was more easily spoiled when compared to the single culture. This study provides insight into the spoilage potential of A. johnsonii and S. putrefaciens during cold storage, which further assists in the application of appropriate technologies to keep the freshness of aquatic foods.

Prediction in the Dynamics and Spoilage of Shewanella putrefaciens in Bigeye Tuna (Thunnus obesus) by Gas Sensors Stored at Different Refrigeration Temperatures

Shewanella putrefaciens have a faster growth rate and strong spoilage potential at low temperatures for aquatic products. This study developed a nondestructive method for predicting the kinetic growth and spoilage of S. putrefaciens in bigeye tuna during cold storage at 4, 7 and 10 °C by electronic nose. According to the responses of electronic nose sensor P30/2, the fitted primary kinetic models (Gompertz and logistic models) and secondary model (square root function model) were able to better simulate the dynamic growth of S. putrefaciens, with high R2 and low RMSE values in the range of 0.96–0.99 and 0.021–0.061, respectively. A partial least squares (PLS) regression model based on both electronic nose sensor response values and electrical conductivity (EC) values predicted spoilage of S. putrefaciens in bigeye tuna more accurately than the PLS model based on sensor signal values only. In addition, SPME/GC-MS analysis suggested that 1-octen-3-ol, 2-nonanone, 2-heptanone, dimethyl disulfide and methylamine, N, N-dimethyl- are the key VOCs of tuna inoculated with S. putrefaciens.

ANALISIS KANDUNGAN MIKROPLASTIK PADA USUS IKAN TUNA MATA BESAR (Thunnus obesus) YANG DIDARATKAN DI PELABUHAN IKAN WAKATOBI

Pencemaran plastik memiliki efek terhadap perairan laut dan terbatasnya informasi mengenai dampak terhadap saluran pencernaan ikan migrasi. Oleh karena itu, penelitian ini bertujuan untuk menganalisis kandungan mikroplastik pada sistem pencernaan ikan yang terletak pada bagian usus dan identifikasi jenis polimer mikroplastik pada daging ikan tuna mata besar yang didaratkan di pelabuhan ikan Wakatobi. Penelitian ini dilaksanakan pada bulan Maret sampai Juli 2020 di Kabupaten Wakatobi. Proses identifikasi kandungan mikroplastik pada usus ikan tuna mata besar dilakukan dengan 4 tahap, yaitu (1) tahap pembedahan ikan, (2) pemisahan densitas, (3) penghilangan senyawa organik, (4) pengamatan visual. Identifikasi jenis polimer mikroplastik pada daging ikan tuna mata besar dianalisis menggunakan fourrier trasform infrared (FTIR). Hasil penelitian menunjukkan bahwa terdapat mikroplastik pada usus ikan tuna mata besar berjumlah dua belas partikel dengan tipe mikroplastik berupa fiber berwarna biru, cokelat dan merah. Ukuran mikroplastik yang ditemukan yaitu 0,701-4,305 mm. Hasil analisis FTIR pada daging ikan menunjukkan senyawa polyethylene ditandai dengan adanya ikatan C=O stretch.

Hydroxyapatite From the Skull of Tuna (Thunnus obesus) Head Combined With Chitosan to Restore Locomotive Function After Spinal Cord Injury

Hydroxyapatite is an important fish bone calcium in tuna head, which is widely used to repair of bone defect. Chitosan is a degradable basic polysaccharide with good biocompatibility and bone guiding, which can achieve targeted delivery to the injured spinal cord after spinal cord injury (SCI). This study aimed to evaluate the beneficial effects of chitosan combined hydroxyapatite (chitosan-hydroxyapatite) nanoparticles on SCI. The result revealed the chitosan-hydroxyapatite particles were successfully constructed and the stability of particles was maintained at low temperature. Moreover, we found chitosan-hydroxyapatite administration could improve SCI, while chitosan alone treatment resulted in no significant increase of the Basso Beattie Bresnahan (BBB) scores compared with the control group. In addition, chitosan-hydroxyapatite particles also significantly reduced the lesion cavity volume and improved the dispersed structure, indicating it could promote the recovery of tissue function of SCI rats. This study explored the effects of chitosan-hydroxyapatite nanoparticles on the location and function of spinal cord injury, provided experimental evidence for further research on its application in spinal cord repair, and helped improve the efficient use of tuna heads.