【作者】 章银良；

【导师】 夏文水；

【作者基本信息】 江南大学 ， 食品科学， 2007， 博士

【摘要】 腌鱼是一种风味独特的传统食品,有着广泛的市场需求。为满足现代生活对食品安全、营养、风味的消费需求,有必要对传统腌制加工技术进行革新。本论文系统研究了鱼腌制过程中的影响因素,食盐渗透扩散规律和生化变化对品质的影响。探索了加快腌鱼风味成熟和延长保藏期的技术手段,建立了优化的腌制工艺。采用浊度比色法建立了一种简便、快速、可靠的分析水产品中食盐含量的新方法。最佳测定条件是:最大吸收波长为385nm, 3.2 mol/L硝酸用量2mL;明胶浓度和用量分别为1.5g/L和2mL;0.5%AgNO3溶液5mL;显色反应的温度在60℃,保温10min。经过与国家标准GB/T12457~90对比分析,两者之间不存在显著性差异,而且用时和成本为国家标准滴定法的1/3,该法切实可行。以海鳗为原料,以食盐含量、水分含量及重量变化为指标研究腌制温度、浓度、食盐纯度、鱼体大小、渗透调节剂和真空对腌制的影响,结果表明,腌制温度越高,则鱼体中食盐内渗量就大。腌制浓度越大,则鱼体中食盐内渗量就大。腌制浓度决定鱼体腌制后重量是增加还是减少,变化范围在15～18%之间。食盐中钙、镁离子对腌制有一定负影响,钙镁离子存在影响鱼体中食盐内渗量的增加,同时影响鱼体水分的失去。鱼体大小对渗透有影响,鱼体越大,食盐内渗量和水分失去减少。腌制液中添加海藻糖可以加速食盐的扩散和水分的脱去,而且随着海藻糖浓度增加而加快。因此在盐渍溶液中添加2%海藻糖就可以明显增加食盐内渗量。真空腌制可以明显增加鱼体中食盐内渗量和水分失去。而且随着真空度的升高作用更加明显。因此可采用真空和添加海藻糖来加速腌制。通过鱼体食盐获得和水分失去来研究食盐扩散渗透规律,考察浓度和温度对渗透扩散系数和活化能的影响。结果表明,随着温度的升高,盐的渗透速度常数随着增加。不同的初始食盐浓度浸渍下,其渗透速度常数随着食盐浓度的增加而增加。盐的扩散系数是温度和初始盐渍浓度的函数,活化能随着初始盐渍浓度增加而减少,活化能的大小是温度影响扩散过程的一个指标。当鱼体盐浓度较小时,温度是加速腌制的重要因素。通过动力学分析,得到了在一定温度和盐渍浓度下,食盐获得(StG)与水分失去(WL)随着时间(t)而变化的拟合方程StG=0.193t/(3.20+t)和WL=0.277t/(3.87+t)。此方程有利于指导生产,即采用高盐浓度腌制,可以加速脱去水分、摄入盐分以及节约后熟时间。采用DSC、FT-IR、SDS-PAGE、荧光等技术手段研究腌制过程蛋白质的生化变化及其对品质影响。结果表明,随着腌鱼制品食盐含量渐渐增大,其肌动球蛋白分子渐渐打开,最后由于肽链上氨基酸侧链间的键桥变化及疏水性区域那样的局部变化,形成蛋白质的聚集而变性。腌制对鱼组织结构的产生了影响。采用扫描电镜(SEM)观察,经过腌制后食盐含量达到12.7%时肌肉组织坚实,而新鲜鱼肌肉结构疏松。质构分析(TPA)表明,随着腌制鱼中食盐含量增加,其硬度和内聚性明显增加,而弹性随着减小。蛋白质变性使得腌鱼制品的口感变差,使鱼的组织结构韧性增加,可食性降低,而且会削弱蛋白质的凝胶性能。在腌制液中添加海藻糖,当肌肉中海藻糖含量达到2.90%时可以抑制蛋白质的变性,使得腌鱼制品的口感、组织结构韧性较好,提高了腌制鱼的品质。肌肉成分的溶出随着温度增加,盐卤中增加的氨基酸量明显。随着盐渍浓度的增加,溶出到盐卤中的氨基酸的数量随着减少。而鱼体肌肉蛋白质的分解,随着盐渍温度和浓度的提高,肌肉中游离氨基酸随着增加。所以采用低温10℃和高浓度20%腌制较为有利。以感官、质构和主要成分为指标,考察腌制和后熟方式对腌鱼品质的影响。结果表明,湿腌的产品比干腌的品质好;真空干燥脱水在缩短干燥时间、抑制和减缓脂肪氧化方面比传统的热风干燥形式稍优越;而热风干燥在腌鱼外观的形成、风味物质的积累等方面存在优势,可以采用真空-热风联用干燥既可以缩短干燥周期,减缓脂肪氧化,又能提供令人满意的产品外观和风味,具有较高的适用性。腌鱼的风味品质通过主要成分含量,感官评定和质构来评价,感官、质构与主要成分之间存在显著的相关性,通过相关性分析,腌鱼制品具有较好的感官及质构性能的两个主要指标是食盐6%,水分活度0.81。通过GC-MS技术对腌腊鱼风味成分分析及感官评定,探索加速风味成熟的途经。采用间歇微波可以加快风味成熟,添加风味蛋白酶对改善腌鱼的品质具有明显的效果。在腌制液中添加0.4%的风味蛋白酶作用2h后再用间歇微波处理1min的样品中所含有的风味物质有大幅度的增加,由对照组的36种风味化合物增加到优化后的61种,同时产生对腌鱼起重要作用的羰基化合物和呈香物质酯类。其制品品质有极显著的提高,腊香味、咬劲和口味等感官评价较对照为优。通过TVBN、TAMN、TVC和TBA等分析来研究气调包装、超高压等技术手段在腌鱼保藏中的作用。结果表明气调包装,超高压处理等能够使腌鱼制品的保藏期有所增加,但是增加的幅度在25℃下大约是3~4天。将海藻糖用于腌鱼保藏,结果表明海藻糖能使得食盐含量为6%的腌鱼在4℃保藏期延长100天,这为鱼腌制工业化生产奠定了非常有利的基础。更多还原

【Abstract】 Cured fish is one of traditional foods with particular flavor , there are broad demands of cured fish in market . In order to satisfy consumption demands of food in safety, nutrition, flavor on modern life, it is necessary to innovate traditional processing technique of cured fish. In this paper, the effect factors, osmotic dehydration phenomena and biochemistry changes of protein of fish muscle during salting were systematically investigated; the techniques of improving flavor ripening and extending the preservation capability of cured fish were tried . The optimization pickling technique was set up.A novel, simple, rapid and reliable turbidity spectrophotometric method to determine sodium chloride in salted fish was developed and validated. The absorbance was measured at 385nm. The method was tested under various conditions: 2mL 1/4 (V/V) nitric acid, 2mL 1.5 g L-1 gelatin, 5mL 0.5% silver nitrate in a total volume of 50mL, mixed and heated at 60℃for 10 min. The accuracy and the results of this method comparing with GB/T12457~90 were not significantly different, this method is feasible to determination salt concentration and has low cost and is not time-consuming compare with GB/T12457~90.The effects of temperature, concentration, salt purity, fish fillet size, osmotic regulator and vacuum on salting process were evaluated through changes of salt concentration, moisture and weight using pike eel as material, the results showed that the higher the brine temperature was, the more fish muscle gain salt. The higher the brine concentration was, the more fish muscle gain salt , The effect of brine concentration on the weight change magnitude of pike eel muscle whether increase or decrease was crucial , the change ranged from 15% to 18%. Calcium and magnesium ion had negative effect on penetration of salt, so it is necessary to use pure salt in pickling. The effect of fillet size on osmotic rate was significant, the bigger the fillet size was, the less water loss and salt gain. When trehalose was added in brine solution, it could significantly accelerate salt gain and water loss, the higher trehalose concentration was, the more water loss and salt gain. Vacuum penetration at 22℃and 25% brine concentration could also accelerate salt gain and water loss, when vacuum degree increase, the effect also increased. So using vacuum and addition trehalose can accelerate salt penetration.The osmotic dehydration phenomena were investigated with salt gain and water loss, the results indicated that rate constant and salt penetration rate increased along with temperature and concentration increase. The salt diffusion coefficient was function of temperature and initial salt concentration. The magnitude of the activation energy was an indication of the temperature influence on the diffusion process. The values of activation energy decreased with initial salt concentration increase, When the salt concentration in muscle decreases, temperature starts to be an important factor for accelerating the process. The kinetics analysis showed that the fitting equations StG=0.193t/(3.20+t)①and WL=0.277t/(3.87+t)②of salt gain and water loss of pike eel muscle with time change were beneficial to guide production and ensure quality at definite brine temperature and concentration. Pickling with high salt concentration can accelerate water loss and salt gain and reduce drying time.The analysis biochemical changes of protein and its effect on quality of cured fish during salting using DSC, FT-IR, SDS-PAGE, fluorescence, etc were carried out, the results showed that along with increasing the salt concentration of pike eel muscle , actomyosin unfold gradually , the bond bridge of amino acids side chain of peptidic chain and hydrophobic region changes resulted in aggregation and denaturation of protein. The scanning electronic microscopy(SEM) showed that pike eel muscle became tight and hardness after salting at concentration of 12.7% and fresh pike eel muscle was loose. Texture profile analysis(TPA) indicated that the hardness and cohesiveness sharply increased with increasing salt penetration of cured fish, whereas the springiness decreased. Protein denaturation in fish not only resulted in toughness in fish fillets, which became inedible, but also impaired gelation properties. When trehalose content was 2.9% in salted pike eel muscle , the denaturation of protein could be inhibited and the quality of salted fish could be improved. The higher the temperature of salting solution was, the more amino acids dissolved in brine of pike eel muscle. The higher concentration of salting solution was, the less amino acids dissolved in brine of pike eel muscle. Whereas decompounding of protein in pike eel muscle was also affected with brine concentration and temperature and they had positive correlation .So it is better to pickle at 10℃and brine concentration at 20%The effect of methods by pickling and drying on quality of cured fish were evaluated with sensory evaluation, texture and principal composition. The results indicated that the quality of brine salting was better than pile salting. Vacuum drying was better than hot-air drying in decrease drying time, inhibition and slowing oxidation of fat, whereas hot-air drying was better in appearance and flavor accumulation of cured fish, so it is nice to combine vacuum drying with hot-air drying for cured fish quality. The quality of cured fish from chemical composition analysis, sensory evaluation and texture test could be analyzed ,the relativity between sensory, texture with chemical composition was significant, so the optimization of two indicators were put forward : salt concentration 6% and water activity 0.81.The methods to accelerate flavor ripening were tried through GC-MS analysis and sensory evaluation, the results indicated that adding flavourzyme and intermittent microwave were very effective. When the flavourzyme(0.4%) was added to brine solution for 2 hours and then deal with 1min by intermittent microwave, The flavor compounds were sharply increased from 36 at control to 61 of optimization technique condition, and carbonyl and ester compounds may be important compounds in cured fish flavor. The cured fish quality was largely improved compared with control in sensory evaluation.Modified atmosphere package (MAP) and ultra-high pressure(UHP) treatment were studied for preservation of cured fish with indicators of TVBN, TMAN, TVC & TBA etc. The results showed that MAP and UHP could extend shelf-life of cured fish ,but the increase magnitude was only for 3~4 days at 25℃. A new kind of additive—trehalose was found out using in preservation cured fish and could extend shelf-life more than 100 days compared with control at 4℃, this research results were foundation to industrialize for cured fish.更多还原