乳糖对鱿鱼中氧化三甲胺热分解反应动力学的影响

为探究鱿鱼高温氧化三甲胺(TMAO)热分解的内源刺激因子,从热分解动力学角度研究还原糖对TMAO热分解生成甲醛、二甲胺(DMA)和三甲胺(TMA)的影响。高温条件下鱿鱼中TMAO降解生成甲醛、DMA和TMA,而还原糖也表现表现下降。通过体外筛选,发现7种还原糖的添加能显著促进鱿鱼上清和TMAO-Fe(Ⅱ)体系中甲醛的产生,其中半乳糖的刺激作用最强,且对鱿鱼上清和TMAO-Fe(Ⅱ)体系中TMAO热分解产生FA、DMA和TMA也表现相似的促进作用。比较研究了TMAO-Fe(Ⅱ)和TMAO-Fe(Ⅱ)-Gal的热分解动力学,发现FA、DMA、TMA和TMAO含量变化符合零级反应动力学,TMAO热分解分为两个阶段,第一阶段表观活化能高于第二阶段,半乳糖的添加能明显降低活化能。因此,为了控制鱿鱼TMAO分解生成甲醛,在鱿鱼制品加工过程中应降低半乳糖等还原糖的添加。     

不同贮藏温度下阿根廷鱿鱼内源性甲醛及相关物质的变化规律

探究不同贮藏温度下阿根廷鱿鱼内源性甲醛及相关物质的变化规律,研究了4 ℃、0 ℃、-20 ℃贮藏条件下鱿鱼体内甲醛(FA)、二甲胺(DMA)、三甲胺(TMA)、氧化三甲胺(TMAO)、氧化三甲胺脱甲基酶活性(TMAOase)、肌原纤维蛋白溶解度、菌落总数的变化。结果表明,随着贮藏时间的延长,鱿鱼体内FA、DMA、TMA和菌落总数呈现上升趋势;TMAO和蛋白溶解度呈现下降趋势;在4 ℃和0 ℃下TMAOase活性呈先上升后平缓的趋势,-20 ℃下TMAOase活性呈先上升后略微降低的趋势;各温度下的甲醛含量和氧化三甲胺脱甲基酶(TMAOase)酶活之间具有显著相关性(r4 ℃=0.791,r0 ℃=0.863,r-20℃=0.825)。本研究为不同贮藏条件下甲醛的控制提供了理论基础。     

真空包装结合甲醛抑制剂对鱿鱼丝贮藏品质的影响

为了探讨鱿鱼制品贮藏过程中内源性甲醛的调控技术,在秘鲁鱿鱼丝加工的复水工序分别浸泡水、0.15%茶多酚及复合甲醛抑制剂——0.05%茶多酚和5 mmol/L柠檬酸,采用普通包装和真空包装制品。通过分析鱿鱼丝制品25℃贮藏过程中营养指标、氧化三甲胺分解产物、TVB-N含量和色差,评价真空包装结合茶多酚(TP)和柠檬酸(CA)甲醛抑制剂对秘鲁鱿鱼丝货架期品质的影响。试验结果显示,鱿鱼丝在室温贮藏过程中发生明显的水分损失,高含量的氧化三甲胺转化为二甲胺和甲醛,褐变反应(P0.05)。相对于普通包装,真空包装能显著降低鱿鱼丝贮藏过程中水分损失和蛋白质分解,抑制氧化三甲胺降解和美拉德反应(P0.05),而对TVB-N的积累无显著影响。添加两种甲醛抑制剂,能显著抑制鱿鱼丝中甲醛和二甲胺的生成,并有效降低鱿鱼丝中TVB-N的形成(P0.05);0.15%茶多酚影响鱿鱼丝的色泽。真空包装结合0.05%茶多酚和5 mmol/L柠檬酸复合甲醛抑制剂,对保持鱿鱼丝贮藏品质,抑制氧化三甲胺降解和美拉德反应效果最佳。     

TG-DSC分析氯化钙抑制鱿鱼氧化三甲胺的热分解作用

氧化三甲胺(TMAO)是鱿鱼制品中内源性甲醛(FA)形成的前体物质。为了研发鱿鱼高温甲醛的高效抑制剂,采用热重-差示扫描量热(TG-DSC)法探讨氯化钙抑制TMAO热分解生成FA和二甲胺(DMA)的反应机制。结果显示,氯化钙能显著抑制鱿鱼上清体系和TMAO-Fe(II)模拟体系中TMAO热分解生成FA、DMA和三甲胺(TMA),并能干扰亚铁离子对该分解反应的促进作用。在氯化钙作用下TMAO-Fe(II)体系中TMAO热分解的TG-DSC曲线出现明显变化,吸热分解峰由3个变为2个,分解温度均明显升高。热分解动力学研究表明,氯化钙使TMAO-Fe(II)中TMAO热分解的活化能从81.14kJ/mol显著上升到3259.78kJ/mol。氯化钙抑制鱿鱼上清中TMAO热分解反应的主要机制是:氯化钙提高了TMAO热分解的活化能。     

不同防腐剂对烤制鱿鱼片贮藏品质的影响

为了延长烤制鱿鱼片的货架期,本文采用37 ℃加速破坏实验,分别研究空白组、添加山梨酸钾组、添加乳酸链球菌素（Nisin）组及添加ε-聚赖氨酸盐组的烤鱿鱼片样品在贮藏7 d中理化指标的变化,考察贮藏过程中烤制鱿鱼片的TVB-N含量、菌落总数、微观结构、pH、色泽的变化,并对其进行感官评价,探究不同防腐剂对烤制鱿鱼片贮藏品质的影响。结果表明:在贮藏的第7 d,乳酸链球菌素处理的烤制鱿鱼片的TVB-N含量比山梨酸钾组、ε-聚赖氨酸盐组、空白组降低了2.35、8.123、9.612 mg·100 g?1;空白组和山梨酸钾处理组烤制鱿鱼的菌落总数在第5 d时超过标准,分别为4.59、4.48 lg CFU·mL?1,ε-聚赖氨酸盐处理组烤制鱿鱼片的菌落总数在第6 d时超过国家标准,含量为5.08 lg CFU·mL?1。乳酸链球菌素处理组烤制鱿鱼片的菌落总数在贮藏过程中没有超过国家标准。不同防腐剂处理的烤制鱿鱼的色泽、质构和感官评分差异显著（P<0.05）。与ε-聚赖氨酸盐和山梨酸钾相比,乳酸链球菌素能有效的抑制烤制鱿鱼TVB-N含量、菌落总数的上升,且能减缓烤制鱿鱼质构和色泽的变化,使烤制鱿鱼保持良好的感官性状,是更有利于烤制鱿鱼贮藏的防腐剂。     

葡萄籽提取物对鱿鱼鱼丸品质的影响

本文以秘鲁鱿鱼为原料,研究了不同浓度的葡萄籽提取物对秘鲁鱿鱼鱼丸品质的影响。分别添加浓度为0、0.025%、0.050%、0.100%、0.200%、0.400%的葡萄籽提取物于鱼丸中,对其进行白度、质构特性、凝胶强度,低场核磁共振(LF-NMR)分析以及甲醛(FA)、二甲胺(DMA),三甲胺(TMA)与氧化三甲胺(TMAO)指标的测定,对秘鲁鱿鱼鱼丸品质进行评定。结果表明,随葡萄籽提取物(GSE)浓度的增加,白度呈现降低趋势,添加浓度低于0.050%时,秘鲁鱿鱼鱼丸白度无显著降低(p<0.05);鱼丸硬度明显提高,弹性无显著性变化(p<0.05);破断力、凹陷距离和凝胶强度显著升高(p<0.05)。添加浓度高于0.050%时,凹陷距离和凝胶强度上升缓慢;GSE能够提高秘鲁鱿鱼鱼丸的持水性,降低鱼丸中水分的流动性,抑制氧化三甲胺的热分解,降低了鱼丸中TMA、DMA和甲醛含量。     

芳樟醇抑制嗜冷杆菌引起的秘鲁鱿鱼甲醛升高

选用天然芳樟醇作为保鲜剂，抑制由近海生嗜冷杆菌L4引起的秘鲁鱿鱼甲醛升高及品质劣变。结果表明，添加芳樟醇的样品，甲醛、二甲胺和三甲胺含量均显著低于同期接种L4的样品（P<0.05），降低倍数在1.3~12.2倍之间。添加芳樟醇后以上3项指标与空白组无显著差异（P>0.05）。而氧化三甲胺含量高于L4组同期指标的1.1~15.9倍。品质指标显示同样的结果，芳樟醇处理组和空白组的感官品质劣变、菌落总数、硫代巴比妥酸值和pH值显著低于L4组（P<0.05）。近海生嗜冷杆菌L4能够促进鱿鱼中甲醛的产生及其品质的劣变，而芳樟醇能够抑制L4引起的鱿鱼中甲醛的增加，提高鱿鱼贮藏品质和食用安全性。     

内源性甲醛对鱿鱼鱼糜凝胶特性的影响

以秘鲁鱿鱼鱼糜为原料,研究凝胶性条件对鱿鱼鱼糜凝胶特性的影响,并优化了鱿鱼鱼糜凝胶条件。实验分为新鲜鱿鱼鱼糜和冻藏鱿鱼鱼糜2组,比较不同凝胶条件下2组鱼糜的甲醛等相关指标的含量变化和凝胶品质的变化。结果表明:相对新鲜鱼糜,冻藏的鱿鱼鱼糜中甲醛、二甲胺、三甲胺含量显著(p0.05)升高,氧化三甲胺含量显著(p0.05)降低,凝胶品质劣化。当低温凝胶化温度为40℃,凝胶化时间为30 min时,经二段式加热鱿鱼鱼糜凝胶表现出的凝胶(质构特性、凝胶强度、弛豫时间T23、持水性和蒸煮损失)品质更好;扫描电镜观察鱼糜凝胶组织微观结构表面较平整、分布均匀。     

不同贮藏温度对南美白对虾中甲醛含量变化的影响

本文研究了不同贮藏温度对南美白对虾中甲醛含量变化的影响。将南美白对虾分别贮藏于20、4、-5和-20℃条件下,贮藏过程中定期测定氧化三甲胺、三甲胺、游离甲醛和游离及可逆结合甲醛的含量并分析其变化趋势。结果表明在20、4和-5℃下,氧化三甲胺含量呈现降低趋势,腐败性物质三甲胺随着温度的升高增长速度变快,游离甲醛的增长速度随温度的降低而变缓;-20℃下贮藏至150 d,氧化三甲胺含量逐渐降低,游离及可逆结合甲醛含量增至6.46 mg/kg,游离甲醛增至3.09 mg/kg,增幅最大;三甲胺仅在贮藏后期有微弱的增长;各温度下,贮藏时间对游离甲醛含量变化的影响显著(p0.05),由此可见冻藏条件最有利于南美白对虾的保鲜,但产生的甲醛含量累积最多。本文为探究冻藏条件下控制甲醛的产生提供了一定理论支持。     

蓝莓叶多酚和大蒜提取物对冷藏鱿鱼鱼丸品质的影响

鱿鱼鱼丸营养丰富,但冷藏期间容易腐败变质,为保持鱿鱼鱼丸品质和延长货架期,采用0.2%蓝莓叶多酚和1%大蒜提取物及二者复合物对鱿鱼鱼丸进行保鲜。分别测定微生物指标和理化指标(硫代巴比妥酸值、挥发性盐基氮、甲醛、三甲胺、氧化三甲胺、白度和凝胶强度),用来评价蓝莓叶多酚和大蒜提取物对鱿鱼鱼丸的保鲜效果。结果表明:4℃冷藏条件下,蓝莓叶多酚和大蒜提取物能够有效抑制微生物生长,减缓脂肪氧化,降低TVB-N值,提高鱼丸强度;同时蓝莓叶多酚和复合保鲜剂能够抑制氧化三胺分解,三甲胺和甲醛的生成,延长鱿鱼鱼丸货架期。     

Effect of processing steps on the physico-chemical properties of dried-seasoned squid

The effects of processing steps on the physico-chemical properties of dried-seasoned squid were studied using two kinds of squids. Browning was observed as indicated by an increase in yellowness (b^∗ value) during the semi-drying and roasting step. The temperature and time of heating and type of roasting, as well as the material itself were the key factors influencing the browning. A high level of trimethylamine oxide (TMAO), and low contents of trimethylamine (TMA) and dimethylamine (DMA) were detected in the raw material. TMAO gradually decreased during the processing, while TMA, DMA and formaldehyde (FA) increased significantly especially in boiled meat. The temperature of boiling was the most crucial factor impacting the production of FA. FA could be greatly decreased during the cooling process by washing with water or changing the roasting techniques. Therefore, to improve the quality of dried-seasoned squid, more attention should be paid to the temperature and roasting techniques during the processing.     

Effects of thermal processing and various chemical substances on formaldehyde and dimethylamine formation in squid Dosidicus gigas

BACKGROUND: Trimethylamine oxide (TMAO) in squid is demethylated to dimethylamine (DMA) and formaldehyde (FA) during storage and processing. This study examined the effects of thermal processing and various chemical substances on FA and DMA formation in squid. RESULTS: The thermal conversion of TMAO was assessed by analysing four squid and four gadoid fish species, which revealed that FA, DMA and trimethylamine (TMA) were gradually produced in squid, whereas TMA increased and FA decreased in gadoid fish. A significant increase in both FA and DMA levels was observed in the supernatant of jumbo squid with increased heating temperature and extended heating time at pH 6–7. Ferrous chloride combined with cysteine and/or ascorbate had a significantly positive effect on FA formation in the heated supernatant of jumbo squid. No significant difference was observed in the levels of Cu and Fe in squid and gadoid fish. The capability of Fe²⁺ to promote the formation of FA and DMA was not completely attributable to its reducing power in squid. CONCLUSION: Non‐enzymatic decomposition of TMAO was a key pathway during the thermal processing of jumbo squid, and Fe²⁺ was a crucial activator in the formation of FA and DMA. Copyright © 2012 Society of Chemical Industry     

ESR studies on the thermal decomposition of trimethylamine oxide to formaldehyde and dimethylamine in jumbo squid (Dosidicus gigas) extract

The effects of ferrous iron, heating temperature and different additives on the decomposition of trimethylamine oxide (TMAO) to formaldehyde (FA) and dimethylamine (DMA) and generation of free radicals in jumbo squid (Dosidicus gigas) extract during heating were evaluated by electron spin resonance (ESR). The thermal decomposition of TMAO to TMA, DMA and FA and free radical signals was observed in squid extract, whereas no DMA, FA and free radical signals were detected in cod extract or in aqueous TMAO solution in vitro at high temperatures. Significant increase in levels of DMA, FA and radicals intensity were observed in squid extract and TMAO solution in the presence of ferrous iron with increasing temperature. Hydrogen peroxide stimulated the production of DMA, FA and ESR signals in squid extract, while citric acid, trisodium citrate, calcium chloride, tea polyphenols and resveratrol had the opposite effect. Similar ESR spectra of six peaks regarded as amminium radical were detected in the squid extract and TMAO–iron(II) solution, suggesting that the amminium radical was involved in the decomposition of TMAO.     

PHYSICOCHEMICAL AND BIOCHEMICAL CHANGES IN WHOLE LIZARDFISH (SAURIDA MICROPECTORALIS) MUSCLES AND FILLETS DURING FROZEN STORAGE

The physicochemical and biochemical changes in whole lizardfish (Saurida micropectoralis) muscles and its fillets kept in air and under vacuum during frozen storage at ?20C for 24 weeks were investigated. The formaldehyde (FA) and dimethylamine contents increased with a concomitant decrease in trimethylamine‐ N‐oxide (TMAO) content as the storage time increased (P < 0.05). The Ca²⁺–adenosine 5′‐triphosphatase activity continuously decreased with a coincidental decrease in salt‐soluble fraction. The disulfide bonds were increasingly formed throughout the storage (P < 0.05). The surface hydrophobicity increased and reached the maximum at week 12 with a subsequent decrease up to the end of storage. In general, the higher changes were observed in samples kept under vacuum than those kept in air. With the same atmosphere used, the whole fish showed slightly higher changes than the fillets. A marked increase in TMAO demethylase (TMAOase) activities was observed up to 12 weeks, followed by the continuous decrease up to 24 weeks of storage. The produced FA might play an important role in inducing protein denaturation and/or aggregation in lizardfish. The TMAOase activity as well as the FA formation could be reduced to some extent with the removal of internal organs and storage in the presence of oxygen. However, a detrimental effect of oxygen, especially on the promotion of lipid oxidation, would be an obstacle.     

Shelf-life extension of cod fillets with an acetate buffer spray prior to packaging under modified atmospheres

Fresh cod fillets (Gadus morhua) were sprayed with a 10% acetate buffer (pH 5.6), packed with an industrial gas-flushing packaging machine under modified atmospheres (50% CO₂-45% O₂-5% N₂, 2cm³/1g gas/ product ratio) and stored at 7^oC for 12 days. Control cod fillets were directly packed and stored under the same conditions. A reduction of the aerobic plate counts was observed immediately after the cod fillets had been sprayed. During storage under modified atmospheres, there was complete inhibition of H₂S-producing bacteria and Enterobacteriaceae in the treated cod fillets. Production of total volatile bases and trimethylamine (TMA) was inhibited in treated fillets for 10 days' storage under modified atmospheres. Inhibition of TMA production can be attributed to growth inhibition of H₂S-producing bacteria, inhibition of the trimethylamine oxide (TMAO)-dependent metabolism of TMAO-reducing bacteria and the stable pH during storage. The shelf-life, at 7^oC, of treated cod fillets, based on cooked flavour score, was almost 12 days, ca 8 days more than shelf-life of the control fillets.     

Effect of frozen storage on the quality of whole fish and fillets of horse mackerel (Trachurus trachurus) and mediterranean hake (Merluccius mediterraneus)

 Whole fish and fillets of horse mackerel (Trachurus trachurus) and mediterranean hake (Merluccius mediterraneus) were assessed for quality (physical, chemical and sensory attributes) changes throughout 12 months of frozen storage at −18 °C. The pH, expressible water (EXW), quantities of trimethylamine (TMA), dimethylamine (DMA), formaldehyde (FA), the total volatile base nitrogen (TVB-N) the thiobarbituric acid number (TBA), peroxide value (PV) and amount of free fatty acids (FFA) increased, while sensory attributes (odour, taste, texture) decreased during the frozen storage period. A comparison of quality scores between whole fish and fillets of horse mackerel and mediterranean hake showed that there were no significant differences (P>0.05) in attribute scores. There were, however, significant differences (P<0.05) in pH, EXW, TMA, DMA, FA, TVB-N, TBA, FFA and PV. Received: 19 April 1996/Revised version: 7 September 1996