小龙虾虾壳酶解液制备及其在小龙虾丸加工中的应用

目的:提高小龙虾虾丸风味特性与营养价值,丰富小龙虾加工产品的多样性。方法:以小龙虾虾壳为原料制备酶解液,通过单因素和正交试验优化确定复合酶法制备小龙虾虾壳酶解液工艺,并对添加有酶解液冻干粉及虾肉的小龙虾“全虾丸”进行营养品质分析。结果:小龙虾虾壳酶解液最佳制备工艺条件为1 g虾壳粉中添加0.5 mL乳酸,60℃预处理40 min,复合蛋白酶(m_{木瓜蛋白酶}∶m_{风味蛋白酶}为3∶1)添加量为5%(质量分数),酶解温度60℃,酶解时间4 h,料液比1∶100 (g/mL),酶解液中蛋白提取率为64.69%。酶解液冻干粉重金属含量均符合水产品重金属限量标准,且含有钙、镁、铁、硒等人体所需常量及微量元素;其成分分析显示,酶解液冻干粉有一定营养价值,在一定程度上可增加食品的鲜香风味,且符合安全标准。小龙虾虾丸的营养和质构分析表明,全虾丸蛋白质含量高,富含多种氨基酸,营养全面,风味独特,黏弹性及咀嚼性良好。结论:添加了虾壳酶解液冻干粉及虾肉的小龙虾虾丸有一定的营养价值,丰富了小龙虾即食产品种类,提高了小龙虾利用率。     

Crayfish Hepatopancreatic Extract Improves Flavor Extractability from a Crab Processing By-product

Incorporation of crayfish hepatopancreatic extract (CHE) improved the extraction of volatile flavor compounds and increased the extract-ability of nonvolatile nitrogen compounds from crab hard tissue (CHT) obtained by mechanical separation of composite processing by-product. Optimum reaction conditions for hydrolysis of CHT protein were 2 hr reaction with 1 mL CHE per 10g CHT at 45°C. Concentration of volatile flavor compounds increased significantly in CHE-treated CHT compared with those from untreated substrate; however, dienals and aromatic hydrocarbons decreased. Pyrazines, especially 2-ethyl-6-methylpyrazine and 2,3-dimethylpyrazine, were in markedly higher concentrations due to CHE treatment.     

Enhanced Inhibition of Listeria monocytogenes by Glycerol Monolaurate with Organic Acids

Glycerol monolaurate (ML) inhibition of Listeria monocytogenes was affected by pH and testing matrix. We investigated antimicrobial effects of ML combined with acetic, benzoic, citric, and lactic acids (AA, BA, CA, and LA) on L. monocytogenes in broth medium and crawfish tail meat. Minimum inhibitory concentrations were lower when ML was combined with each acid in dual combination. ML combined with sublethal amounts of AA, BA, or LA gave greater inhibition than for the most active compound alone. No interaction occurred between ML and CA. ML had no influence on pH of media containing organic acids. ML or LA in crawfish tail meat had reduced activity. ML activity was influenced by type of organic acid used. Combining ML with organic acids may provide similar protection to other precooked ready-to-eat foods.     

Influence of Gender and Spawning on Meat Quality of Australian Red Claw Crayfish (Cherax quadricarinatus) Stored at 2 °C

ABSTRACT:  Shell-on tails of male (M), nonspawning female (F), and spawning female (SF) Australian red claw crayfish ( Cherax quadricarinatus ) ( n = 270) were aerobically stored at 2 °C up to 10 d to monitor meat quality changes under a retail condition. Percentage protein of SF muscle was higher ( P < 0.05) and moisture and ash content lower ( P < 0.05) than those of M and F muscles. The pH of muscle changed during storage, with SF generally having a lower value than M or F ( P < 0.05). Lipid oxidation increased during the 1st 5 d and no significant difference existed between the 3 muscle groups. Cooking yield of SF (91.72%) at 10 d was significantly lower than that of M (96.25%) or F (97.81%), and its muscle shear force was also higher ( P < 0.05) than M at 0, 3, 5, and 7 d and than F at 5 and 7 d. Sensory panel results (cooked meat tenderness, juiciness) were significantly correlated with instrumental results (shear force, cooking yield), with SF showing a lower meat tenderness, juiciness, and overall acceptability than M and F samples.     

吉林省部分市售小龙虾中Hg2+、甲基汞、 乙基汞含量的监测与分析

目的了解吉林省内部分市售小龙虾Hg~(2+)、甲基汞、乙基汞污染水平。方法采集吉林省松花江流域和非松花江流域内的小龙虾样品,粉碎后经5mol/LHCl提取,C_(18)色谱柱分离,高效液相色谱-电感耦合等离子体质谱检测样品中Hg~(2+)、甲基汞、乙基汞含量。结果在采集的两流域小龙虾样品中,虾黄和虾肉均未检出Hg~(2+)和乙基汞,小龙虾样品中汞的主要存在形态是甲基汞,未发现超标现象。结论小龙虾中甲基汞含量均低于限值,可安全使用。     

基于培养基法和高通量测序法分析冷藏小龙虾优势腐败菌

为揭示4 ℃冷藏小龙虾贮藏期间微生物菌群多样性及优势腐败菌种类,以传统培养基法作为对照,采用高通量测序技术分别鉴定小龙虾样品在鲜样期、腐败中期、腐败末期的腐败菌属,探究贮藏期间微生物菌群变化趋势。2 种测序方法对比发现,高通量法检测到的菌属更具多样性,培养基法提取的腐败菌均包含在高通量测序菌属内。结果表明,培养基法提取优势腐败菌共11 株,其中气单胞菌（Aeromonas jandaei）致腐能力最强,弗氏柠檬酸杆菌（Citrobacter freundii）致腐能力最弱;此外,高通量测序法显示希瓦氏菌（Shewanella sp.）、肉杆菌属（Carnobacterium sp.）、环丝菌属（Brochothrix sp.）、嗜冷菌属（Psychrobacter sp.）、漫游球菌属（Vagococcus sp.）、不动杆菌属（Acinetobacter sp.）等在腐败末期时的物种丰度为90.57%。2 种方法比对可以确定,小龙虾的优势腐败菌有希瓦氏菌、肉食杆菌、环丝菌属、嗜冷菌属、漫游球菌属、不动杆菌属、气单胞菌、束毛球菌属（Trichococcus sp.）等。     

嘉兴地区网络订餐食品安全调查与研究

目的 通过调查与取样对嘉兴地区网络订餐食品的安全情况进行分析和评估。方法 采取随机问卷调查的形式对市民网络订餐情况进行调查。根据调查结果针对食品安全风险较高的小龙虾和凉菜进行集中抽样检测, 重点检测微生物、重金属和寄生虫等指标, 并对检测结果进行分析。结果 抽取活小龙虾10批, 进行寄生虫和重金属检测。虾鳃、虾黄、虾肉、虾肠均未检出寄生虫, 虾鳃、虾黄、虾肉重金属检测结果均合格, 其中1批样品虾黄中镉含量接近国家标准限值。抽取熟小龙虾10批, 进行微生物检测, 结果均合格。抽取凉菜60批, 进行微生物检测, 其中菌落总数超标6批, 大肠埃希氏菌超标8批, 金黄色葡萄球菌超标1批。结论 嘉兴地区网络订餐食品安全性总体可靠。小龙虾存在重金属污染风险, 凉菜类食品微生物污染风险较高, 应引起监管部门的重视, 加强监督执法力度。     

熟制麻辣小龙虾冷藏和冻藏条件下的品质变化

研究熟制麻辣小龙虾在冷藏和冻藏条件下的品质变化,将小龙虾油炸后拌料入味,真空包装并进行沸水 煮制杀菌（沸水煮制20 min后快速冷却）,分别在4 ℃和－18 ℃条件下贮藏,通过感官评分、菌落总数、大肠杆 菌数量、总挥发性盐基氮（total volatile base nitrogen,TVB-N）值、pH值及食盐含量测定对麻辣小龙虾的品质变 化进行研究。结果表明：从感官评定结果、菌落总数和TVB-N值综合评判,4 ℃冷藏和－18 ℃冻藏的麻辣小龙虾 能够保持最佳品质的贮藏时间分别为4 周和4 个月;在保质期内,麻辣小龙虾的菌落总数＜4.7 （lg（CFU/g））, TVB-N值＜30 mg/100 g,pH值在弱碱性范围内变化;4 ℃冷藏小龙虾贮藏前3 周的食盐含量呈逐渐升高趋势（达 1.99%）,贮藏3 周后变化不显著（P＞0.05）,而－18 ℃冻藏小龙虾的食盐含量变化缓慢,保持在1.6%～1.8%范 围内。经感官评定,保质期内的麻辣小龙虾风味鲜美、品质优良。     

熟制小龙虾冷冻贮藏期间的品质变化研究

目的研究熟制小龙虾冷冻贮藏期间的品质变化。方法以熟制的带壳和去壳小龙虾为原料,将其在-18℃下贮藏1个月,通过检测虾肉的脂肪氧化程度、pH值、挥发性盐基氮(total volatile base nitrogen,TVB-N)值、盐溶性蛋白含量、色泽、质构特性等指标,考察小龙虾在冷冻贮藏期间的品质变化。结果在贮藏期间,带壳和去壳小龙虾虾肉的脂质氧化程度、pH值、TVB-N均呈上升趋势,总巯基含量和盐溶性蛋白含量持续下降,去壳虾肉颜色变化不显著,而带壳虾肉的色泽参数L*值和白度值W显著降低,硬度、弹性、咀嚼度和回复力在贮藏前期下降显著,之后下降趋势较为平缓。结论带壳和去壳的虾肉在贮藏前期(0～2周)的各指标无显著差异,而冷冻贮藏3周之后,带壳虾肉的品质优于去壳虾肉,冷冻贮藏一个月后,带壳虾肉和去壳虾肉均可正常食用。     

超声联合微酸性电解水处理克氏原螯虾条件优化及对其品质影响

目的 探寻超声协同微酸性电解水处理对克氏原螯虾杀菌效果以及贮藏期品质的影响。方法 考察微酸性电解水有效氯浓度、浸泡时间、超声功率三者分别对微生物的影响,分析4 ℃贮藏期间联合处理对克氏原螯虾菌落总数、总挥发性盐基氮、丙二醛、色差、感官等的影响。结果 在微酸性电解水中浸泡10 min、有效氯浓度为60 mg/L、超声功率为405 W的条件下,克氏原螯虾菌落总数与空白组相比降低了1.48 lg(CFU/g),与单一处理相比杀菌作用更强。在冷藏期间,联合处理组能够抑制克氏原螯虾菌落总数的增长,其总挥发性盐基氮和丙二醛的上升速度均低于未处理组,对延缓样品的脂肪氧化与腐败变质有较好效果。结论 与对照组相比,超声协同微酸性电解水处理有良好的杀菌效果,能更好地保持克氏原螯虾的品质并延长冷藏货架期至4 d以上。