INFLUENCE OF PYROPHOSPHATE (PPI) AND ADENOSINE 5`- TRIPHOSPHATE (ATP) ON MICROSTRUCTURE AND THERMOSTABILITY OF SILVER CARP MYOFIBRILA PROTIENS

Zhuolin Wang¹, Yuanyong Tian², Yumeng Lin¹, Yuki Ogasawara³, Tetsuro Yamashita³, Chunhong Yuan³,

¹United Graduate School of Agricultural Sciences, Iwate University, Morioka 0208550, Japan

²College of Food Science and Technology, Dalian Ocean University, Dalian 116023, China

³Faculty of Agriculture, Iwate University, Morioka, Japan 

^*Corresponding author: u3221010@iwate-u.ac.jp

Effect of pyrophosphate (PPi) on structural and thermostability change of silver carp myosin and actin was studied in comparison with adenosine 5`-triphosphate (ATP). Myosin and actin in myofibrils treated with 2 mM PPi-Mg in 0.2 M NaCl underwent dissociation effectively at 0°C. Nevertheless, 2 mM ATP-Mg treated myofibrils exhibited aggregation under the same condition. Thermostability revealed by chymotryptic digestion of both myosin and actin treated with PPi-Mg decreased markedly when incubated at 30~50 °C or 42, 45, 48 °C for 1~ 120 min at 0.2 M NaCl compared to control. In ATP-Mg treated sample, myosin thermostability showed little stable than PPi-Mg sample as evidenced by the remaining band intensity of S1, but both of them denatured quickly compared with control, suggesting after lose the protective effect of actin, myosin became more sensitive to thermal denaturion. Actin in ATP-Mg treated myofibrils exhibited a complete resistance to chymotryptic digestion when incubated at the same condition distinguished with PPi-Mg treated sample and control. This phenomenon was also observed when myofibril was incubated at 0.1~2.0 M NaCl, 35 °C for 30 min. while actin in PPi-Mg treated sample and control denatured remarkably with the increase of salt concentration. Almost all of chymotryptic resistance actin failed to convert to G-actin as well as F-actin, suggesting the apparently native actin was incapable of depolymerization and polymerization. Therefore, addition of ATP-Mg could not only dissociated myosin and actin effective, but also induced actin aggregation to a “stubborn” structure, which retain the hydrophobic amino acid exposing during heating related to resistance of chymotryptic digestion.

Keywords: PPi-Mg, ATP-MG, Silver carp, chymotryptic digestion, phase contrast microscope, myosin, actin

SLIGHTLY ACIDIC ELECTROLYZED WATER-SLURRY ICE: SHELF-LIFE EXTENSION AND QUALITY MAINTENANCE OF MACKEREL (PNEUMATOPHORUS JAPONICUS) DURING CHILLED STORAGE

Bingjie ZHANG¹  Weiqing LAN^{1,2,3, *}  Lin LIU¹  Tianting PU¹  Yuxiao ZHOU¹  Jing XIE^1,2,3*

¹College of Food Science and Technology, Shanghai Ocean University, Shanghai 201306, China

²Shanghai Aquatic Products Processing and Storage Engineering Technology Research Center, Shanghai 201306, China

³National Experimental Teaching Demonstration Center for Food Science and Engineering (Shanghai Ocean University), Shanghai 201306, China

* Corresponding author: wqlan@shou.edu.cn; jxie@shou.edu.cn

Different ice treatments were applied for the preservation of mackerel (Pneumatophorus japonicus). The purpose of study was to assess the efficacy of SAEW-SI, flake ice and slurry ice on the quality of mackerel (Pneumatophorus japonicus) during chilled storage. The quality changes of samples treated with flake ice (Control), slurry ice (SI) and slightly acidic electrolyzed water-slurry ice (SAEW-SI) in microbiological, physicochemical, protein characteristic and sensory evaluation were investigated during chilled storage. SAEW-SI showed a significant advantage for the inhibition of microbial growth, which could extend the shelf-life for another 144 h at least compared with Control group. SAEW-SI treatment also had a strong inhibition for the increase of pH, total volatile basic nitrogen (TVB-N), K value, histamine and metmyoglobin (MetMb) content. Results of texture profile analysis (TPA) and water holding capacity (WHC) indicated that SAEW-SI can obviously suppress the decrease of hardness value, and have a better protective effect on muscle structure compared to flake ice and SI (P<0.05). During the whole experiment, the highest sensory scores and a* were obtained in SAEW-SI group which indicated SAEW-SI treatment could maintain better sensory characteristics. According to the results of thiobarbituric acid reactive substances (TBARS) and fluorescence spectroscopy analysis, SAEW-SI treatment could effectively retard protein degradation and lipid oxidation compared with Control and SI group. In maintaining the quality of mackerel, SAEW-SI shows a better effect than SI due to the synergistic effect of fence factors. The results demonstrated that the shelf-life of mackerel could be extended and the quality of mackerel could be maintained effectively with SAEW-SI treatment during chilled storage.

Keywords: Mackerel, Slightly acidic electrolyzed water-slurry ice, Shelf-life, Quality, Chilled storage

COMBINED EFFECT OF MORINGA (Moringa oleifera) WATER EXTRACTS AND VACUUM PACKAGING ON THE QUALITY AND LIPID OXIDATION OF SUN-DRIED PUNTI (Puntius sophore) DURING STORAGE

Md. Golam Rasul^1,*, Chunhong Yuan², Kefeng Yu³, Koichi Takaki⁴, A. K. M. Azad Shah¹

¹Department of Fisheries Technology, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh

²Department of Food Production and Environmental Management, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Japan

³Sanriku Fisheries Research Center, Iwate University, Heta 3-75-1, Kamaishi 026-0001, Japan

⁴Faculty of Science and Engineering, Iwate University, Ueda 4-3-5, Morioka 020-8551, Japan

^*Corresponding author: rasul@bsmrau.edu.bd 

Due to lipid oxidation, sun-dried products have a distinct off flavor, which discourages product usage and limits variety. In addition, there is a frequent complaint about the quality of dried fishes available in the market. This research aimed to investigate the effect of moringa water extracts pretreatment (1.5, 2.5 and 3.5%) and vacuum packaging on the quality and lipid oxidation of sun-dried punti (Puntius sophore) during storage at ambient temperature for 7 months. Biochemical, aerobic plate count, and sensory changes of dried P. sophore were monthly analyzed. Total phenolic content, total flavonoid content, and DPPH radical scavenging activity of moringa water extracts were also evaluated. Moringa water extracts had potent antioxidant activity. Moringa extract treated and vacuum packed dried fishes showed lower aerobic plate count, total volatile basic nitrogen than the untreated vacuum packed samples. Vacuum packaging and moringa treatment reduced significantly the lipolysis (acid value) and oxidation of lipid (peroxide value and thiobarbituric acid reactive substance) in P. sophore. Application of moringa water extracts did not affect significantly the sensory properties of the product. Results demonstrated that pre-treatment with moringa water extract (2.5%) and vacuum packaging could be an alternative to reduce the quality deterioration and lipid oxidation, and improve the quality as well as shelf life of this dried product during processing and storage.

Keywords: Moringa water extracts, Puntius sophore, Vacuum packaging, Quality, Lipid oxidation

COMPARATIVE PROTEOMICS ANALYSIS OF THREE COMMERCIAL TUNA SPECIES THROUGH SWATH-MS BASED MASS SPECTROMETRY AND CHEMOMETRICS

Lingping Hu^1,2, Hongwei Zhang³, Zhiheng Hu^1,2, Yaoxian Chin², Xiaomei Zhang³, Jianchu Chen¹, Yaqin Hu^2*

¹College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058, China

²College of Food Science and Technology, Hainan Tropical Ocean University, Sanya 572022, China

³Food and Agricultural Products Testing Agency, Technology Center of Qingdao Customs District, Qingdao, Shandong Province 266002, China

^*Corresponding author: 1004346262@qq.com 

The adulteration of tuna is found as attenuation of morphological characteristics during processing due to the exhaustion of tuna resource. The authenticity of tuna is now concentrated in the seafood supply chain. Protein, as the most important component of tuna muscle, plays a very important role in tuna. In this study, the protein relative quantitation of 3 commercial tuna species (skipjack tuna, bigeye tuna and yellowfin tuna) were revealed through the developed sequential window acquisition of all theoretical fragment ion mass spectra (SWATH-MS)-based proteomic analysis with 81 proteins being reliably quantified. Further protein biomarkers discovery was carried out by chemometrics, leading to 14 proteins screened as potential biomarkers. Hierarchical clustering analysis showed that the screened protein biomarkers have the ability to distinguish the 3 tuna species. Gene ontology (GO) annotation of the screened protein biomarkers most of them were relevant to molecular functions.

Keywords: tuna; proteomic; mass spectrometry; chemometrics

CORRUPTION ABILITY REGULATING EFFECTS OF LUXS IN SHEWANELLA PUTREFACIENS: ANALYSIS FROM THE PERSPECTIVE OF QUORUM SENSING AND ACTIVATED METHYL CYCLE

Zhiheng Hu¹², Yaqin Hu^2*

¹College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Integrated Research Base of Southern Fruit and Vegetable Preservation Technology, Fuli Institute of Food Science, Zhejiang University, Hangzhou 310058

²College of Food Science and Technology, Hainan Tropical Ocean University, Sanya 572022

^*Corresponding author: 1004346262@qq.com 

Shewanella putrefaciens (SHP) is one of common specific spoilage organisms (SSOs) which results in the typical corruption in aquatic product. Current research found that the corruption characteristics of Shewanella species may be regulated via quorum sensing (QS) system while the AI-2 QS system which is mediated via gene luxS has been reported having potential regulating effects on the corruption characteristics expression in in Shewanella species. Meanwhile, the gene luxS is not only involved in the synthesis of QS molecule Autoinducer-2 (AI-2), but also a vital regulatory gene in the activated methyl cycle (AMC). The complex metabolic cycle indicates that the impacts of metabolic pathways and involved key circulating substances mediated via luxS should be considered when explore the regulating effects of luxS in a more comprehensive way. In our study, the luxS mutant strain of SHP was constructed for revealing the corruption ability regulating effects of gene luxS. The impacts of AI-2/luxS quorum sensing (QS) system and activated methyl cycle (AMC) were considered, and the involved key circulating substances were supplied to clarify the roles of two pathways mediated via luxS. Growth experiments indicated that the luxS deletion did not lead to significant growth differences, but certain growth defects associated with culture environment and exogenous additives were found in mutant strains. The less biofilm formation, diminished H₂S production capacity and weaker corrupting effects on fish juice were observed in mutant strains, while these characteristic down regulations could be offset via the supplements of luxS mediated circulating substance including S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), methionine (Met), homocysteine (Hcy) and 4,5-dihydroxy-2,3-pentanedione (DPD). Our results suggested that the luxS deletion declined the corruption ability of SHP, which may be closely related to the disorder of AMC and non-generation of QS molecule AI-2.

Keywords: Shewanella putrefaciens, luxS, quorum sensing, activated methyl cycle, corruption ability