A 160-kDa Protein Is Essential for Hemocyanin-derived Melanosis of Prawn

ABSTRACT A purified 160-kDa protein, isolated from the cuticle of kurama prawn and named melanosis collaborating factor (MCF), was a key factor in promoting melanosis by a cooperative reaction with hemocyanin-derived phenoloxidase but hemocyanin itself was incapable of producing black pigment. The enzymatic activity of MCF in the body of the prawn was very stable against the process of freezing and thawing; the enzyme maintained more than 80% of its activity after 3 mo of storage at −2 5 °C. These results indicated that MCF, acting in conjunction with hemocyanin-derived phenoloxidase, played a crucial role in postharvest melanogenesis in prawn.     

Postharvest Microbiology of Farm-reared, Tropical Freshwater Prawn (Macrobrachium Rosenbergii)

ABSTRACT: The microbiological quality of farm-reared, tropical freshwater prawn ( Macrobrachium rosenbergii ) stored at 2 different temperatures was studied. The prawn muscle was found to have the initial bacterial load of 10⁴ cfu/g. The lactics and vibrios were in the range of 10² cfu/g, while the E. coli , aeromonads, staphylococci, anaerobes, and molds were in the level of 10¹ cfu/g. Salmonella and Vibrio cholerae were present in the prawn muscle. The prawn muscle held at room temperature (28 ± 2 °C) was organoleptically acceptable up to 8 h, when the bacterial load was more than 10⁶ cfu/g. However, the prawn muscle stored at freezer temperatures (−10 to −15 °C) was found to be in acceptable condition even after 30 d of storage and the bacterial load was fluctuating in the range of 10³ to 10⁴ cfu/g.     

Optimization of parameters for cerium（III） biosorption onto biowaste materials of animal and plant origin using 5-level Box-Behnken design：Equilibrium,kinetic, thermodynamic and regeneration studies

Response surface methodology （RSM） employing 5-level Box-Behnken design was used to optimize the biosorption of cerium（III） onto biowaste materials of animal and plant origin viz. prawn carapace （PC） and corn style （CS）. Various process parameters viz. pH （A：3.0-9.0）, biomass dosage （B：0.05-0.35 g/L）, initial metal concentration （C：50-350 mg/L）, contact time （D：2-6 h） and temperature （E：20-60 ℃ were chosen for optimization. A log transformation was suggested by the Box-Cox plot in the present case. A low p-value of〈0.0001 validated the significance of the model. Maximum Ce（III） uptake of 218.3 mg/g for PC and 180.2 mg/g for CS was noted under optimum conditions. Among the equilibrium isotherms, Freundlich model was found to be the best fitted one suggesting a heterogeneous mode of biosorption on PC whereas Langmuir model showed the best fit suggesting homogeneous mode of cerium biosorption on CS. This was further confirmed by scanning electron microscopy （SEM）. Kinetic studies showed better applicability of pseudo-first order model suggesting physisorption as phenomena underlying the process. Film-diffusion was suggested by the non-linearity of the Boyd plot. Thermodynamic studies showed that the process was endothermic and spontaneous. FTIR analysis confirmed a major involvement of the participation of amide, amines, ketones and primary alcohol groups during Ce（III） biosorption. EDAX analysis confirmed the major participation of carbon group during Ce（III） biosorption. This was the first report on parameter optimization of Ce（III） biosorption onto biowaste materials using 5-level Box-Behnken experimental design which might be helpful for the recovery of Ce（III） from aqueous environment.     

酶法水解虾头生产虾调味汁

本文报告了利用中性蛋白酶水解虾头生产虾调味汁的研究。实验结果表明,水解虾头生产虾调味汁的最佳条件是在酶用量1.4%,水解时间20小时,水解温度40℃,ph6.8。在此条件下,虾头的水解率可达33.6%。水解液具有浓郁的虾风味,可作为调味汁。     

对虾肠道中产毒镰孢菌抑制菌的筛选与鉴定

为了获得对产毒镰孢菌具有抑制效应的海洋细菌,从对虾肠道中分离细菌,并将分离得到的优势细菌与产T-2毒素的禾谷镰孢菌(Fusarium graminearum)(FG1207)进行固体对峙培养,具有抑菌圈的细菌菌落即为产毒镰孢菌的抑制菌。然后选取对FG1207具有抑制作用的细菌与FG1207进行液体共同培养,用LC-MS/MS技术检测菌悬液中T-2毒素含量,最后对具有抑制FG1207的生长和降解T-2毒素效果的细菌进行16s r RNA序列鉴定和VITEK2细菌生化鉴定。实验结果分离得到8株优势细菌,其中一株对FG1207的生长具有明显的抑制作用;LC-MS/MS检测发现该细菌与FG1207共同培养菌悬液中未检测到T-2毒素,说明该细菌不仅能够抑制产毒镰孢菌的生长,还能降解T-2毒素。经16s r RNA鉴定该细菌为海洋尼泊尔葡萄球菌(Nepal Staphylococcus Aureus),相似度为99.93%,VITEK2细菌生化鉴定的相似度为96.86%。     

三维石墨烯泡沫脱除对虾加工副产物中Hg (II)的研究

汞（mercury,Hg）是一种毒性强、分布广、难降解的环境污染物,易富集在对虾的内脏和头部,限制了对虾加工下脚料的综合利用。以对虾加工副产物中Hg（Ⅱ）的脱除为研究目的,利用三维石墨烯泡沫（3D graphene foam,GF）大的比表面积和丰富的羟基、羧基官能团,与Hg（Ⅱ）螯合,实现对对虾加工副产物中Hg（Ⅱ）的脱除。分别利用原子吸收光谱、紫外吸收光谱、甲醛滴定法测定脱除前后对虾加工副产物中Hg（Ⅱ）、蛋白质、氨基酸含量的变化。实验结果表明,GF质量轻,经氧化后含有大量的孔隙结构以及丰富的官能团,在pH6,吸附平衡时间20 min的脱除条件下,GF对对虾加工副产物中Hg（Ⅱ）的脱除率达92.01%,而对蛋白质、氨基酸态氮的保存率分别为94.92%、93.89%。因此,将对虾加工副产物通过GF处理,可以显著（P<0.05）减少加工副产物中Hg（Ⅱ）的残留量,提高对虾加工副产品的食用安全性。     

蛋白质的组成对盐溶蛋白热诱导凝胶特性的影响研究

肌肉盐溶蛋白质形成凝胶的特性是肉制品加工中最重要的功能特性之一,以对虾肉为试材,分别以对虾肉盐溶蛋白热诱导凝胶的硬度、弹性以及黏性为依据,通过聚丙烯酰胺凝胶电泳图谱的比较,得出不同蛋白质的组成对热诱导凝胶特性产生较大的影响,主要的蛋白带出现在31～212ku之间;其组成为肌球蛋白、肌动蛋白、肌原纤维蛋白碎片;电泳图谱中肌球蛋白带宽且颜色深的,其热诱导凝胶的加工特性就越好。     

养殖对虾中氯霉素残留的放射免疫分析

采用放射免疫分析法测定了湛江市水产市场3份新鲜养殖对虾及2份出口养殖对虾氯霉素残留量。结果表明,本方法的检测限量为0.15ppb,3份新鲜养殖对虾体内氯霉素残留量均大于0.15ppb,2份出口养殖对虾氯霉素残留量均小于0.15ppb。提示放射免疫分析法可作为水产品中氯霉素残留量的有效检测手段。