The use of sorbic acid in salted fish

Summary. It has been shown that the development of Hemispora stellata Vuill and red halophilic bacteria in salted snoek ( Thyrsites atun Euph.) can be combated successfully by the use of sorbic acid during salting of the fish. Applications of sorbic acid by dipping of the fish in salt-sorbate solutions proved to be more effective than the use of a mixture of salt and sorbic acid in the salting of fish. When the preservative was mixed with the salt, a severe breakdown of sorbic acid, catalysed by fish constituents which migrated into the salt, occurred during salting. In contrast with this the sorbic acid in salted fish was shown to be rather stable.
Though the experiments were confined to limited experimental saltings, and some of the statements might not hold completely for full scale salting, it should be mentioned that in practice the application of dipping in salt-sorbate solutions also gave good protection against development of halophilic moulds and bacteria.     

腌鱼中硝酸盐还原菌的筛选及系统发育分析

微生物作用是硝酸盐还原成亚硝酸盐的主要原因,而亚硝酸盐在一定条件下会合成强致癌物质——亚硝胺类化合物,存在潜在的食品安全问题。从浙江省特色腌制水产品腌鱼中分离形态颜色各异的菌株,应用硝酸盐还原实验快速筛选具有硝酸盐还原能力的菌株,进而对筛选的菌株进行形态观察、革兰氏染色、生理生化与分子生物学鉴定。最终筛选出有两株菌具有硝酸盐还原性,F-1菌株为Psychrobacter glacincola,F-2菌株为Psychrobacter faecalis。     

模拟肉制品加工条件下影响N-亚硝胺的形成因素

为探讨肉制品加工条件下影响N-亚硝胺的形成因素,本实验模拟肉品加工条件,研究温度、pH、底物浓度之比对N-亚硝基二甲胺（NDMA）和N-亚硝基二乙胺（NDEA）形成的影响,以及pH、底物浓度对N-亚硝基吡咯烷（NPYR）形成的影响。结果表明,NDMA和NDEA的形成量随着温度的升高而增加,随着pH的升高而降低:当温度大于80℃时,NDMA和NDEA的生成量显著增加（p<0.05）;在pH5.4～6.2之间,降低速度较快,在pH6.2～7.0时,降低速度缓慢。随着pH的升高,由吡咯烷（PYR）生成NPYR的量变化不大（p>0.05）,而由脯氨酸（Pro）生成NPYR的量则呈下降趋势（p<0.05）。二甲胺盐酸盐（DMA·HCl）与二乙胺盐酸盐（DEA·HCl）相比,DMA·HCl与NaNO2反应更容易形成N-亚硝胺,且均在低温肉制品加工温度下就可以形成;Pro与PYR相比,PYR与NaNO2反应更容易形成NPYR,且均在较高温度下才可以形成。上述四个反应中当NaNO2过量时更容易生成N-亚硝胺。实验结果表明,较高的温度、较低的pH、较高的亚硝酸钠可以促进N-亚硝胺的合成,因此在肉制品加工中应控制这些因素从而减少N-亚硝胺的生成。      

亚硝酸盐还原酶对咸鱼中亚硝酸盐的降解条件与效果研究

为了探明亚硝酸盐还原酶(Nitrite Reductase,NiRs)对咸鱼中亚硝酸盐的降解作用及应用条件,实验以亚硝酸盐降解量为评价指标,通过单因素实验和Design-expert响应面实验分析咸鱼加工过程中加入亚硝酸盐还原酶(NiRs)的酶浓度、温度、时间的最适条件,并通过测定色差值和感官指标分析NiRs对咸鱼品质的影响。结果表明:NiRs在咸鱼加工中的最佳应用条件是酶浓度4mg/m L、温度34℃、时间5h,亚硝酸盐降解率可达到32.7%。加入NiRs不影响咸鱼的品质,对咸鱼风味有提升作用。研究结果表明在咸鱼生产中添加NiRs可有效降解亚硝酸盐,在保证咸鱼的食用安全性的同时,为腌制水产品的加工提供理论依据和技术支撑。     

腌制咸鱼中嗜盐菌分离鉴定及特性研究

从腌制咸鱼中筛选出一株中度嗜盐菌CNY0820,该菌革兰氏阳性反应,杆状,宽度0.6μm～1μm,长度1.5μm～2.9μm,产芽孢,分泌淀粉酶,过氧化氢酶和酯酶,明胶水解反应阳性,氧化酶、硝酸盐还原、MR和VP反应均为阴性。生长盐度为0%～25%(NaCl,w/v),最适盐度0.5%;温度范围20℃～45℃,最适温度40℃;pH值为4.0～12.0,最适pH值为8.0。经16SrDNA序列比对及系统发育树分析,该菌属于Halobacillus,但又与进化距离最近的Halobacillus trueperi存在一定差异。该菌的研究对腌制食品中嗜盐菌分类及防止嗜盐菌污染有一定意义。     

盐渍鱼酶解制备鱼露及挥发性风味物质的研究

在对Alcalase2.4L和Papain双酶分步酶解盐渍鱼酶解过程研究的基础上酶解鲜鱼和半年盐渍鱼制备鱼露,运用感官分析和顶空固相微萃取(HS-SPME)结合气质联用(GC-MS)法对其风味进行比较分析。结果表明:Alcalase2.4L、Papain双酶分步酶解盐渍鱼酶解效果较好,先加Papain6h后再加Alcalase2.4L效果较好,但鲜味氨基酸的比例不如先加Alcalase2.4L后加Papain高;与鲜鱼酶解鱼露相比,虽然盐渍鱼使蛋白酶的酶解效果有所降低,但盐渍鱼酶解鱼露的风味较好,较接近传统鱼露的风味,且含有挥发性酸类,但具有鱼露特征香味的挥发性风味物质没有检出,说明需进一步发酵才能达到传统成熟鱼露的风味。     

亚硝酸盐还原酶对咸鱼中亚硝酸盐的降解条件与效果研究

为了探明亚硝酸盐还原酶（Nitrite Reductase,NiRs）对咸鱼中亚硝酸盐的降解作用及应用条件,实验以亚硝酸盐降解量为评价指标,通过单因素实验和Design-expert响应面实验分析咸鱼加工过程中加入亚硝酸盐还原酶（NiRs）的酶浓度、温度、时间的最适条件,并通过测定色差值和感官指标分析NiRs对咸鱼品质的影响。结果表明:NiRs在咸鱼加工中的最佳应用条件是酶浓度4mg/m L、温度34℃、时间5h,亚硝酸盐降解率可达到32.7%。加入NiRs不影响咸鱼的品质,对咸鱼风味有提升作用。研究结果表明在咸鱼生产中添加NiRs可有效降解亚硝酸盐,在保证咸鱼的食用安全性的同时,为腌制水产品的加工提供理论依据和技术支撑。      

Water activity and salt content relationship in moist salted fish products

A linear relationship between water activity ( a _W) in moist salted fish products and NaCl molality was found: ( a _W) SF = 1.002–0.042 m ; where m is the NaCl molality considering it to be in true solution in the total water content of the product.
The linear approximation was analyzed with reference to the a _W values of pure NaCl solutions and to a thermodynamic approach for a _W prediction; it was found consistent and appropriate for a _W estimation in moist salted fish products, with errors within the accepted range for intermediate moisture foods (IMF).     

The transnitrosation of secondary amines S-nitrosocysteine in relation to N-nitrosamine formation in cured meats.

The reactions at 37°C of S-nitrosocysteine hydrochloride with three secondary amines, N-methylaniline, morpholine and pyrrolidine, have been studied at pH 2.65, 5.5 and 9.75. The reactions result in the formation of the N-nitroso derivatives of the three amines at all three pH values studied. The rates of N-nitrosation and final yields of products in these reactions were compared with those in reactions in which the N-nitrosation of the secondary amines was effected by nitrite. The comparative rates varied considerably according to the amine being studied and the reaction pH. The relevance of these findings to nitrosamine formation in cured meat and in vivo are discussed. Reaction of S-nitrosocysteine hydrochloride with all three amines at pH 9.75 and with N-methylaniline at pH 5.5 resulted in some N-nitrosamine formation in the headspace above the reaction mixture. The stability of S-nitrosocysteine hydrochloride was studied as a function of pH. The compound was fairly stable at pH 2.65, but decomposed rapidly at pH 5.5 and 9.75. The decomposition reaction at pH 5.5 followed three-halves order kinetics, but that at pH 9.75 did not conform to simple kinetics.     

咸鱼中生物胺降解菌的筛选与降解特性研究

为获得用于咸鱼等腌制水产品的生物胺降解菌,本文采用生物胺初筛培养基与高效液相色谱技术分析,研究从传统方法加工的咸鱼中分离筛选具有降解生物胺的菌株,通过VITEK 2鉴定系统进行菌种鉴定,并分析菌株的生长曲线、降解生物胺动力学、温度、p H、盐度、生物胺底物浓度等特性,及在咸鱼中接种菌株对产品生物胺的影响。结果表明:从咸鱼中分离筛选到三株具有降解生物胺的菌株,分别是鼠李糖乳酸菌(Lactobacillus rhamnosus,Lr)、植物乳杆菌(Lactobacillus plantarum,Lp)、戊糖片球菌(Pediococcus pentosaceus,Pp);对生物胺降解的最适温度为30~35℃,最适p H为5.5~6.0,对食盐有较好的耐受性,在食盐浓度≤80 g/L时对生物胺的降解作用尤为明显,Lr与Lp之间无拮抗作用;接种了生物胺降解菌的咸鱼产品中腐胺、尸胺、组胺、酪胺等生物胺含量均显著性降低(p<0.05),而接种Lr∶Lp=1∶2的混合菌种的咸鱼产品生物胺含量下降幅度最大。      

真空包装淡腌白鱼的辐照保藏研究

研究不同辐照剂量对真空包装淡腌白鱼灭菌与保藏的影响。利用60Co辐照源分别按照0.5、1.0、2.0、3.0、5.0kGy进行加工处理,检测辐照前后菌落变化,贮藏保鲜。结果表明D10值为1.2kGy,DS值为2.5kGy。辐照组品质指标明显好于未辐照组,2.5kGy组好于1.2kGy组,对感官无影响。23℃,30d贮藏期间菌落总数(TVC)、挥发性盐基氮(TVBN)、感官评价指标等均稳定,2.5kGy可作为淡腌白鱼的辐照加工剂量。      

A novel method for the determination of sodium chloride in salted fish

A novel, simple and reliable spectrophotometric method to determine sodium chloride in salted fish was developed and validated. The method was based on the reaction of chloride with silver nitrate and the determination of turbidity of silver chloride formed. The absorbance was measured at 385 nm. The method was tested under various conditions, and we confirmed an optimal operation with 2 mL 1:4 (v/v) nitric acid, 2 mL 1.5 g L^?1 gelatin, 5 mL 0.5% silver nitrate in a total volume of 50 mL, mixed and heated at 60 °C for 10 min. The range of linearity and the detection limit were 0.4–24 mg L^?1 and 0.2 mg L^?1, respectively. The relative standard deviations and the recovery were 0.83% to 2.87% and 93.74% to 103.6%, respectively. The accuracy of this method was comparable with Volhard method, and it was cheap and successfully applied to determine sodium chloride in salted fish.     

添加脂肪的种类和比例对炸鱼丸品质及N-亚硝胺含量的影响

为考察添加脂肪的种类和比例对炸鱼丸理化指标和N-亚硝胺含量的影响,本研究在鱼丸基础配方上,分别添加大豆油、猪背膘、鸡皮、猪背膘+鸡皮（质量比1∶1）,添加比例为10%和20%,加工出8组炸鱼丸样品。分析各组样品的加工损失率、持水性、凝胶强度、白度、TBARS值、亚硝酸盐残留量以及9种N-亚硝胺含量。结果表明:较低的油脂添加量（10%）,有利于降低鱼丸的加工损失率,提高持水性和凝胶强度,降低TBARS值和亚硝酸盐残留量。特别是添加10%猪背膘+鸡皮（D组）的炸鱼丸质构品质最好,持水性（79.90%±0.05%）和凝胶强度（3504±94 g·mm）显著高于其他组样品（p<0.05）,加工损失率（12.8%±0.2%）明显低于其他处理组。所有鱼丸样品均含有NPYR、NDPA、NDBA和NPIP,其中NPYR含量最高（p<0.05）。添加鸡皮的样品N-亚硝胺含量较高,添加10%大豆油和20%猪背膘的鱼丸,总N-亚硝胺含量较低,N-亚硝胺含量与脂肪添加量没有显著相关性。      

咸鳓鱼中产组胺菌的分离与鉴定

针对细菌引起的腌制水产品中生物胺残留问题,胺以传统工艺腌制的咸鳓鱼为对象,利用组胺菌筛选培养基,从不同腌制时期的咸鳓鱼样品中对产组胺微生物进行了筛选,通过16S r DNA测序完成了分离菌株种属鉴定,采用PCR扩增检测了分离菌株组氨酸脱羧酶基因携带情况,并用高效液相色谱(high performance liquid chromatography,HPLC)检测了分离菌株发酵液中组胺的含量。结果表明,分离纯化后共获得32株疑似产生物胺细菌,分布于3个属8个种。葡萄球菌属细菌是优势分离菌株,共计29株,以腐生葡萄球菌数量最多,共16株;24株分离菌株携带组氨酸脱羧酶基因; 23株分离菌株发酵液中测出不同浓度的组胺含量,产组胺菌发酵液组胺平均含量达38. 10μg/m L,其中,1株腐生葡萄球菌菌株发酵液中组胺质量浓度高达100. 21μg/m L,是分离菌株中组胺积累能力最强的菌株。咸鳓鱼生产中产组胺菌的研究,对评估咸鳓鱼的安全性,科学指导其发酵菌株筛选具有理论指导意义。     

咸鱼中戊糖片球菌产亚硝酸盐还原酶的条件优化

利用从咸鱼中分离出的戊糖片球菌(Pediococcus pentosaceus,P.pentosaceus),对其产亚硝酸盐还原酶(Nitrite Reductase,NiRs)的产酶条件进行优化。单因素实验设计考察接种量、pH、培养温度和培养时间等因素对产酶量的影响,再通过正交实验L9(34)确定了最佳的产酶条件。结果表明,pH对产酶的酶活性影响最大,戊糖片球菌产亚硝酸盐还原酶的最佳产酶条件为接种量4%,pH为6,培养温度为35℃,培养时间为48h。本文为进一步研究亚硝酸盐还原酶性质及在咸鱼加工中应用,以降低咸鱼等腌干鱼类产品中亚硝酸盐及亚硝基化合物提供技术支撑。      

腌鱼制品中乳酸菌及其对品质影响的研究进展

随着人们生活水平的提高,饮食结构和消费习惯的变化,人们对食品品质的要求也越来越高,改变传统食品加工方式,开发低盐、健康、安全的腌制品加工技术势在必行。腌鱼是我国重要的传统水产食品,具有咸鲜相宜、风味独特的特点,深受国内外消费者的喜爱。腌鱼加工过程中,蛋白质和脂肪被肌肉中的内源酶和微生物酶降解为小肽、氨基酸和脂肪酸等,这个过程中发生的蛋白水解、脂肪氧化和脂肪水解三大反应决定了腌鱼制品的营养品质。乳酸菌是腌制食品自然发酵中的常见菌种之一,可通过参与一系列的物理化学反应,改善食品的营养特性,提升产品品质和安全性,赋予产品独特的风味,延长食品保质期,在食品行业被广泛应用。本文综述了国内外腌鱼制品中的乳酸菌及其对产品品质的影响,为创新开发新型腌鱼制品提供理论依据,也为传统食品的技术改造提供新的思路。     

The effects of ascorbic acid and sorbic acid on N-nitrosamine formation in a heterogeneous model system

The effects of competitive nitrosation by ascorbic acid and sorbic acid on N-nitrosamine formation were studied in a heterogeneous protein-based model system containing a 20% non-aqueous phase. The reactions were examined at 37°C with an aqueous phase pH of 5.25. Under certain conditions ascorbic acid enhanced the nitrosation of secondary amines. The overall extent to which ascorbic acid affected N-nitrosation was found to depend on the time-scale of the reaction and also the phase in which N-nitrosamine formation occurred. Sorbic acid reduced N-nitrosation in both phases of the heterogeneous system.     

Influence of nitrate, ascorbic acid, and nitrate reductase microorganisms on N-nitrosamine formation during Korean-style soysauce fermentation.

Traditional Korean soysauce samples were collected from households in Chinju, Gyeongnam, Korea and analysed for volatile N-nitrosamines. Five of 24 samples contained NDMA (range = 1.6-10.4 micrograms/l) which was the only volatile N-nitroso compound found. Soysauce made from well water contained NDMA more often (4 of 6 samples) than soysauce made from tap water (1 of 18). This suggests that the water source is a determinate in the NDMA content of soysauce, probably due to a higher nitrate content of well water. The source of salt used did not clearly influence NDMA content. Soysauce was prepared in the laboratory using traditional methods but with 0 to 400 mg/l nitrate and in some cases made 6.5 to 65 mM in ascorbic acid and fermented for 120 days. The NDMA content of the samples was positively correlated with increasing nitrate concentration. Nitrate at 400 mg/l resulted in an NDMA content of 203 micrograms/l. Ascorbic acid substantially inhibited NDMA formation. All samples contained large numbers of nitrate reductase-containing organisms (greater than 1 x 10(7) CFU/ml).