【作者】 靳肖；

【导师】 周德庆；

【作者基本信息】 中国海洋大学 ， 食品科学， 2010， 硕士

【摘要】 近年来,鱿鱼丝等水产干制品甲醛超标的报道越来越多,而甲醛是一种原生质毒,被国际癌症研究署定为A1类致癌物,因此鱿鱼丝的食用安全性引起了社会的广泛关注。实验中发现当鱿鱼加工成鱿鱼丝,以及鱿鱼丝在贮藏过程中都会产生大量甲醛,其产生机理未见报道。因此,研究鱿鱼丝甲醛的产生机理,有助于研究鱿鱼丝甲醛的控制技术,从而提高其食用安全性。本论文主要以鱿鱼和鱿鱼丝为主要研究对象,对鱿鱼及其干制品内源性甲醛产生的化学途径、残留变化及控制技术进行系统基础的研究。主要对生鲜鱿鱼到鱿鱼丝成品,以及鱿鱼丝贮藏过程中的甲醛、二甲胺等物质进行监测,同时建立TMAO-Fe(II)体外模拟体系,进一步对比验证,探索鱿鱼丝内源性甲醛产生的可能途径,最后研究了适合鱿鱼丝贮藏的环境及条件,得到如下结果：1.鱿鱼和鱿鱼丝甲醛的本底含量。实验采集鱿鱼样品102个,测得鱿鱼甲醛平均值为14.93 mg/kg;鱿鱼丝样品257个,测得鱿鱼丝甲醛平均值为47.54 mg/kg,可见鱿鱼加工成鱿鱼丝过程中有新的甲醛产生。将鱿鱼进行分割,测定不同部位甲醛含量,发现鱿鱼样品不同部位甲醛含量由高到低依次为鱿鱼内脏、肌肉和头部,甲醛含量分别为27.18mg/kg、7.59mg/kg和5.36mg/kg,经非参数检验,鱿鱼样品不同部位甲醛含量存在显著性差异。对可食性鱿鱼肌肉的不同部位(内层、中层、外层)甲醛含量进行分析,得出不同部位的鱿鱼肌肉甲醛含量由高到低依次为鱿鱼肌肉内层、中层和外层,甲醛含量分别为8.19mg/kg、7.93mg/kg和7.21 mg/kg。经非参数检验,鱿鱼肌肉不同部位甲醛含量不存在显著性差异。2.鱿鱼冻藏过程中甲醛含量的变化。将4种不同的鱿鱼样品贮藏于-20℃,持续8个月,发现甲胺、二甲胺含量迅速上升主要是在冻藏后2个月,随后,甲醛、二甲胺含量上升速度减缓,从冻藏后6个月到8个月中,甲醛、二甲胺含量基本趋于稳定。3.鱿鱼丝加工过程甲醛的残留变化。以秘鲁鱿鱼为原料,监测了整个加工工艺过程中甲醛、二甲胺、三甲胺和氧化三甲胺含量变化趋势。发现在鱿鱼丝在整个加工过程中,氧化三甲胺含量逐渐减少,甲醛含量处于上升趋势,二甲胺和三甲胺含量也在逐渐增加,尤其是在蒸煮、焙烤环节中,甲醛含量上升最为明显。4.鱿鱼浸泡过程中甲醛的残留变化。用不同浓度的甲醛溶液对鱿鱼和鱿鱼干进行浸泡实验,研究证明,鱿鱼和鱿鱼干对甲醛具有一定的吸附性,且样品中甲醛残留量均随浸泡时间延长而持续上升,随浓度的增大,甲醛的残留量越大,并伴随有刺激性气味；同时,浸泡液中甲醛残留量随时间延长呈下降趋势。证明甲醛溶液浸泡过的水产品,即使用清水冲洗,也只能除去体表的甲醛和异味,残留在鱿鱼组织中的甲醛不会被除去,而对人体产生危害。5.鱿鱼丝氧化三甲胺热分解模拟体系的研究。研究了加热温度、加热时间和初始pH对TMAO-Fe(II)热分解作用的影响,同时与鱿鱼丝水提液中氧化三甲胺热分解规律进行对比,建立了鱿鱼丝氧化三甲胺体外模拟体系,研究鱿鱼丝中氧化三甲胺热分解机理。结果表明：随着温度升高,氧化三甲胺热分解反应越剧烈；在加热30min后,甲醛和二甲胺生成量基本稳定；当pH值为5.0时,铁(Ⅱ)对氧化三甲胺热分解的促进作用最明显。同时研究了八种添加剂对TMAO热分解作用的影响,为今后研究控制鱿鱼丝FA生成提供依据。其中,单独添加EDTA、Vc、Cys、Fe3+等物质对甲醛生成量影响不大；蔗糖对甲醛的生成具有微弱的促进作用；Fe2++Vc、Fe3++Vc、Fe2++Cys、Fe3++Cys、Fe2+对于促进甲醛生成作用明显,因此铁对于鱿鱼丝甲醛的产生具有重要作用。同时,柠檬酸和茶多酚具有降低氧化三甲胺热分解产生甲醛的作用,可作为鱿鱼丝理想的甲醛抑制剂。6.贮藏条件和包装方式对鱿鱼丝甲醛含量的影响。研究温度、湿度、光照等不同贮藏条件和真空、包装和散装包装方式对鱿鱼丝贮藏过程中甲醛含量变化的影响。结果表明,鱿鱼丝在贮藏过程中会有新的甲醛产生,且温度、湿度、光、照及包装方式等均可影响甲醛含量变化,低温、较高湿度、避光贮藏和普通包装处理能延缓鱿鱼丝在储藏过程产生的甲醛量,为其贮藏包装提供一定的参考。本实验测定了鱿鱼和鱿鱼丝的本底含量,并且研究鱿鱼丝在加工及贮藏过程中甲醛的残留变化,证明鱿鱼丝在加工贮藏过程中会产生新的甲醛。目前针对鱿鱼丝甲醛产生的机理却未见报道,本研究结合TMAO-Fe(II)体外模拟体系,揭示鱿鱼丝甲醛产生机理及其影响因素。最后研究了适合鱿鱼丝的包装条件和材料,以控制鱿鱼丝内源甲醛产生,为确保其食用安全提供理论指导。更多还原

【Abstract】 More and more cases of excessive formaldehyde (FA) in dried fishery products such as shredded squid were reported in recent years, since formaldehyde is a protoplasmic poison and classified as A1 carcinogenic substance by International Cancer Research Agency (ICRA), food safety of shredded squid has become a social concern. It was found that a great amount of FA was produced during the shredded squid processing and the following storage, but little was reported about the production mechanism. Control technology can be achieved by studying the FA production mechanism and therefore ensure the food safety of shredded squid. The production mechanism, residue and control technology of FA in squid and dried fishery products were studied in this paper with Dosidicus gigas and its shredded products as materials. In order to explore the mechanism, FA and dimethylamine in fresh squid and shredded squid were determined during the storage, meanwhile an in vitro model system of TMAO-Fe(II) was established for a further confirmation. Possible chemical mechanism of formaldehyde production in shredded squids was explored; finally, suitable conditions for the storage of shredded squids were studied. The results were listed as below:1. Background content of FA in shredded squids. Among the 102 squid samples and 257 shredded squid samples, average value of FA in squid was 14.93 mg/kg, and 47.54mg/kg was for shredded squid, these experimental results confirmed the FA production during the processing. Different parts of squid was divided and their FA content were determined, the FA of squid viscera, muscle and head were ranged with order of amount, the FA content were 27.18mg/kg,7.59mg/kg and 5.36mg/kg, respectively. Significant differences of nonparametric test were found among those data. FA content in different layers of edible muscle were found to be inner layer the highest, middle layer the moderate and the outer layer the lowest, the FA content were 8.19mg/kg,7.93mg/kg and 7.21mg/kg, respectively, no significant differences of nonparametric test observed.2.4 species of squid samples were stored at -20℃for 8 months. Rapid increase of FA and DMA content were found in the first 2 months, the increasing rate declined in the following months, the FA and DMA content were stable during the last 3 months.3. Residual changes of FA during processing of shredded squid. Content changes of FA, DMA, TMA and TMAO were monitored during the overall processing of shredded squid made of Dosidicus gigas. It was found that the content of TMAO decreased during the overall processing, the content of DMA and TMA increased gradually. The increase of FA content was the most obvious, especially during the boiling and baking stages.4. Residual changes of squids soaked with FA solution. Squids and dried squids were soaked in FA solutions at different concentration. The FA absorption of squids and dried squids was confirmed, the residual content of FA increased as the raise of soaking time and concentration and accompanied with a pungent odor, at the same time, the content of FA of the FA solution was in a downward trend. Any fishery products soaked with FA solution could only remove the FA on the surface of the products and the smell, while the FA in the products would be harmful for human health.5. Thermal decomposition of TMAO model systems of shreded squid. The effect of heating temperature, heating time and pH on thermal decomposition TMAO was studied and compared with thermal decomposition of TMAO of water extraction from shredded squid; TMAO-Fe(II) model systems of shredded squid were employed to study the thermal decomposition of TMAO. The results showed that:with the temperature increases, the reaction of thermal decomposition of TMAO is severe; after heating for 30min, the content of FA and DMA remained stable; when pH value is 5.0, Fe2+ could promote the thermal decomposition of TMAO most significantly. This study further showed that the effect of 8 additives on thermal decomposition of TMAO. With EDTA, Vc, Cys, Fe3+ added, they served as basis for controlling FA in shreded squid afterwards. The study showed that there was a little impact on formation of FA by those additives. Sucrose played a weak role in promoting the formation of FA; Fe2++Vc、Fe3++Vc、Fe2++Cys、Fe3++Cys、Fe2+could significantly increase the formation of FA. At the same time, citric acid and tea polyphenols could decrease the content of FA, which can be used as an ideal inhibitor in squid.6. Effects of different storage conditions and packaging on the FA content of shreded squid. The effects of different storage conditions (temperature, humidity and light) and packaging methods (vacuum, common and bulk packaging) on the changes of FA content of shreded squid were investigated. The results showed that the shredded squid could produce FA during storage time, and the storage conditions affecting the content of FA of shreded squid mainly include temperature, humidity, light and packaging methods, meanwhile, low-temperture, high humidity, darkness and common packaging could delay the changes of FA content, providing some reference for the storage conditions and packaging methods of the shreded squid.The study determined the background content of FA in squids and shreded squid, and monitored FA content in shreded squid during processing and storage, which proved that the squid could produce FA during the processing and storage. At present, FA formation mechanism of shreded squid has not been reported, and this study combined with TMAO-Fe (Ⅱ) model system to reveal the factors affecting the reaction, and studied the suitable materials and conditions for the packaging of shredded squid to control endogenous formaldehyde, providing technical reserves to ensure the safety of shreded squid.更多还原