【作者】 戴妍；

【导师】 周光宏；

【作者基本信息】 南京农业大学 ， 食品科学， 2011， 硕士

【摘要】 盐水鸭是我国传统肉制品之一,具有香、酥、嫩、鲜的特点,深受广大消费者的喜爱。而近年来盐水鸭加工企业为了尽可能延长保质期,通常将盐水鸭真空包装后,再次进行二次杀菌处理。二次杀菌处理后在一定程度上改变了盐水鸭特有的风味,尤其是121℃杀菌处理后的盐水鸭,风味与感官受到很大影响,最终影响市场消费。那么究竟哪种杀菌方式能最大限度地保持食品原有的风味,有待于做更多的基础研究来论证,为进一步改造盐水鸭工艺提供实用性的理论。国内外仍鲜有研究二次杀菌处理对肉制品风味的影响方面,具体的研究结果如下：1、盐水鸭风味分析方法的完善本章在刘源等优化的SPME-GC-MS技术分析盐水鸭肉中主要风味化合物成分方法的基础之上,进一步完善SPME-GC-MS方法,旨在更为全面地分析鸭肉中风味化合物组成,分别基于非极性色谱柱(DB-5MS)和极性色谱柱(DB-innowax),对三种不同极性的萃取头：弱极性75μm CAR/PDMS.中等极性50/30μm DVB/CAR/PDMS和强极性85μm PA,以市售桂花鸭集团盐水鸭肉为研究对象,分别进行风味优化分析实验,发现鸭肉中主要风味化合物大都由非极性化合物组成,极性化合物只占其中很小的一部分,因此使用非极性的75μm CAR/PDMS萃取头和DB-5MS (30 m×0.25mm i.d.)色谱柱以及极性的50/30μm DVB/CAR/PDMS萃取头和DB-innowax (30m×0.25 mm i.d.)色谱柱共同鉴定鸭肉风味化合物组成,则能全面分析鸭肉中主要挥发性化合物组成,初步分析,一共有67种主要的挥发性风味化合物从鸭肉中检测出,其中包括烯烃、醛类、酮类、醇类、含氮化合物以及苯系物、呋喃类、酸类、酯类和烷烃等。2、不同二次杀菌盐水鸭风味及感官评定分析本章采用顶空固相微萃取(HS-SPME)和气质联用(GC-MS)分析技术研究了5组不同处理(对照组,99℃,108℃,微波,121℃)盐水鸭产品挥发性风味变化,同时对5组鸭肉进行了一系列感官评定试验,其中包括综合感官品评定实验和三角实验(108℃组和微波组),结果显示：鸭肉中共鉴定出76种主要风味化合物,包括3种酸类、14种酮类、20种醛类、11种醇类、5种酯类、7种烷烃类、1种呋喃类、11种含硫含氮及苯系物、4种烯烃；对照组、99℃和108℃二次杀菌组分别鉴定出57、56、59种风味化合物,远高于微波组(51种)和121℃杀菌组(52种),鸭肉主要挥发性化合物峰累计相对百分含量中对照组(87.27%)远高于二次杀菌99℃组(83.27%),108℃组(81.6%),微波组(84.06%),121℃组(84.33%)。与二次杀菌组(微波,121℃)相比,108℃组感官评定得分稍高,而三角实验中微波组和108℃组中在口感上无显著性区分,结合仪器测试,此组鸭肉更为接近盐水鸭原有风味(对照组)。3、不同二次杀菌的盐水鸭肉滋味变化分析滋味活性化合物,主要包括游离氨基酸,丁二酸和5’-核苷酸以及食盐等基本化合物。二次杀菌处理组鸭肉中丙氨酸(A1a)和水分含量显著下降(P<0.05),pH值下降明显,粗蛋白含量以及5’-核苷酸含量显著升高(P<0.05),其中99℃组鸭肉中粗脂肪含量显著低于(P<0.05)其他组含量。对照组鸭肉中丁二酸含量显著高于(P<0.05)121℃组鸭肉,108℃组、微波组、121℃组鸭肉中的鲜味浓度值(EUC)、游离氨基酸含量、苦味物质和甜味物质含量较为近似,与其它组鸭肉相比,其鲜味物质含量较高,在五组鸭肉中一共检测到2种微量的可溶性还原糖存在(葡萄糖和果糖),二次杀菌组鸭肉中还原糖总量显著增加,但肉中还原糖含量较少,对鸭肉风味影响不大,二次杀菌处理的鸭肉中硫胺素含量呈现增加的趋势,对照组和108℃组鸭肉中硫胺素含量最少,可能其中的硫胺素大量热解,与更多挥发性风味产生有关,基于以上结果,对照组和99℃组鸭肉中口味更为清淡爽口,微波组鸭肉中鲜味较明显,因此需要进一步改进盐水鸭前面几步的加工工艺,从而适当提高鸭肉中鲜味物质含量,而不是依赖二次杀菌工艺。4、不同二次杀菌盐水鸭肉脂肪氧化分析五组鸭肉中共鉴定出的主要脂肪酸为：棕榈酸C16：0、硬脂酸C18：0、油酸C18：1、亚油酸C18：2和花生四烯酸C20：4,主要甘油三酯(TGs)为：LLO、OOO、POO、SOO、POS、PPS和SSO,与对照组鸭肉相比,二次杀菌组鸭肉中羰基值、过氧化值升高,中性脂肪(NL)和极性脂肪(PL)中脂肪酸组成中,C16：0,C16：1和C18：1含量有下降的趋势,而C18：2,C18：3和C20：4含量有上升的趋势,多不饱和脂肪酸(PUFA)总相对百分含量升高,中性脂肪(NL)中的多不饱和脂肪酸升高的趋势更为明显,其中对照组和99℃组中C18：2相对百分含量显著(P<0.05)低于其他组鸭肉。对照组、99℃组以及108℃组鸭肉中C18：3相对百分含量显著(P<0.05)低于其他组鸭肉,游离脂肪酸(FFA)中,对照组鸭肉中C18：2相对百分含量显著(P<0.05)低于其他组鸭肉,对照组与微波组中C18：3相对百分含量显著低于(P<0.05)其他组鸭肉,与对照组鸭肉相比,二次杀菌组鸭肉中甘油三酯(TGs)组成中以3个不饱和脂肪酸组成的甘油三酯含量较高,其中OOO、POO和POP形成的差异更为显著,而以一种或二种饱和脂肪酸构成的甘油三酯的相对百分含量较低,其中SOO、POS、PPS和SSO形成的差异显著,与脂肪酸相比,由甘油三酯类化合物引起脂肪氧化,产生不良风味的影响较小,总之,由于二次杀菌处理的盐水鸭肉脂肪中多不饱和脂肪酸含量显著上升,更易引发自动氧化反应,导致肉中异味如(蒸煮味)产生等产品感官恶化。更多还原

【Abstract】 Cooked Chinese Nanjing duck was one of the traditional Chinese featured meat products, It was famous for its delicate processing, savory, and tender and umami-like flavour and so on. In resent years, many factories which process ducks usually applied many different post-production heat treatments into duck products after packing, especially 121℃group ducks. The flavour and sensory were influenced much, furthermore the market for these ducks following post-production heat treatments was also influenced. Therefore, we should figure out which heat treatments group ducks could reserve the most part of its flavour in order to modify the processing steps of cooked Chinese Nanjing ducks. The studies on the impact of flavour in meat products during post-production heat treatments were less nowadays. The contents and results were as follows:1 The optimization on the analysis methods of volatile compoundsThis chapter was that we have done more to improve and perfect the volatile analysis technology (SPME-GC-MS) of cooked Chinese Nanjing ducks in order to entirely analyze the main volatile composition in duck meat. We have done a series of SPME fibers optimizations experiments including bipolar 75μm CAR-PDMS, moderate polar 50/30μm CAR/DVB/PDMS and polar 85μm PA fibers separately based on non-polar DB-5MS column and polar DB-innowax column. We found that volatiles in ducks were formed by mainly non-polar compounds, whereas polar compounds were only a small part of duck meat. So we should apply on both a bipolar fiber 75μm CAR-PDMS using a non-polar DB-5 (30 m×0.25 mm i.d.) column and a moderate polar fiber 50/30μm CAR/DVB/PDMS using a DB-innowax (30 m×0.25 mm i.d.) column in order to analyze the volatile composition in ducks comprehensively. There were mainly 67 volatile compounds (alkanes, aldehydes, kenones, alcohols, N-containing and benzezes, furan, acids, esters alkenes et al) identified in duck meats. 2 The changes of volatile compounds and sensory in duck groups following various post-production heat treatmentsThe changes in volatile compounds of traditional cooked Chinese Nanjing ducks during different post production heat treatments groups (Control,99℃,108℃, Microwave, 121℃) were analyzed by headspace solid phase microextraction (HS-SPME) combined with GC-MS. We also carried out comprehensive sensory analysis in these 5 group ducks, whereas triangle sensory analysis between 108℃group ducks and microwave group ducks. Results indicated that mainly 76 volatile compounds were identified, including acids (3 kinds), ketones (14 kinds), aldehydes (20 kinds), alcohols (11 kinds), esters (5 kinds), alkanes (7 kinds), furans (1 kind), N-,S-,benzene- containing compounds(11 kinds) and alkenes (4 kinds) in duck meat.57,56, and 59 kinds of volatile compounds were identified in control group ducks and post production heat treatment at 99℃and 108℃respectively, and higher than microwave (51 kinds) and 121℃(52 kinds) heat treatment group. Control group ducks had the higher relative contents of total peak from major volatile compounds (87.27%) compared with other post production heat treatment groups (99℃,83.27%; 108℃,81.6%; microwave,84.06% and 121℃,84.33%). Compared with microwave and 121℃group ducks,108℃group had higher score in the sensory analysis, but in triangle sensory analysis, The difference between 108℃group and microwave group ducks was not significant. Combined with sensory analysis, we could conclude that flavour of 108℃group was more similar to control group.3 The change of taste compounds and sensory in duck groups following various post-production heat treatmentsTaste compounds including free amino acids, succinic acid and 5’-nucleotides and chemical factors including moisture, pH, protein, crude fat and sodium chloride were evaluated in Cooked Chinese Nanjing ducks following different heat treatments including Control group,99℃group,108℃group, microwave group and 121℃group. Heat treatments decreased (P<0.05) the contents of Alamine, moisture and muscle pH value, but increased (P<0.05) the contents of protein and 5’-nucleotides. The 99℃group had significantly lower content of crude fat compared with other groups (P<0.05). The control group had significantly higher succinic acid content than 121℃group (P<0.05). Higher heat (108℃, microwave,121℃) treatment groups had similar equivalent umami concentrations (EUC), contents of 5’-nucleotides, free amino acids, and the derived contents bitter, sweet taste components compared with other treatment groups.108℃, microwave,121℃group ducks had more umami-taste compared with other treatment group ducks. The contents of soluble sugars were higher in 108℃, microwave,121℃group ducks, but the minor amounts of sugar could not impact final flavour of duck meat. The thiamine content in ducks following post-production heat treatments increased significantly, and the control and 108℃group ducks had the least amount of thiamine content probably due to thiamine thermal degradation excessly and more flavour formation.Based on these results, the control and 99℃group ducks were more light and tasty. The microwave group had more umami-like taste compounds. It appears important not to further process at higher temperatures, there may be some opportunities for modifying the primary processing steps to improve the content of important contributing umami-taste like compounds 5’-nucleotides.4 The change of fatty acids, fat oxidation, triglycerides in duck groups following various post-production heat treatmentsThe main fatty acids in 5 group ducks were methyl palmitate (C16:0), methyl stearate (C18:0), methyl oleate (C18:1), methyl linoleate (C18:2), and methyl arachidonic (C20:4) the main triglycerides in these ducks were LLO, OOO, POO, SOO, POS and PPS. Compared with control group ducks, the carbonyl value, peroxide value and PUFA content increased in these treatment groups. From the data obtained from NL and PL fractions in ducks, we found that the percentages of C16:0, C16:1 and C18:1 decreased whereas C18:2, C18:3 and C20:4 increased, and the increasing tendency of PUFA level in Neutral lipids (NL) was more significant. The percentage of Methyl linoleate (C18:2) in control and 99℃group was significantly (P<0.05) lower than other group ducks. Methyl linolenate (C18:3) in control,99℃and 108℃group ducks were significantly lower (P<0.05) than other treatment groups. About free fatty acids, the percentages of methyl linoleate (C18:2) in control group was significantly lower (P<0.05) than from other treatment ducks, methyl linolenic (C18:3) in control and microwave groups were significantly (P<0.05) lower than other groups. The percentages of triglycerides composed of 3 unsaturated fatty acids in these treatment group ducks were significantly higher (P<0.05) than other group ducks, such as OOO, POO and POP, whereas the triglycerides composed of 2 or 1 unsaturated fatty acids were significantly lower (P<0.05), such as SOO, POS, PPS and SSO. The impact of oxidation reactions and formation of off-flavour induced by TGs were less than fatty acids, In a word, the content of polyunsaturated fatty acids in ducks would be increased following various post-production heat treatments and these treatments could cause auto-oxitation in meat and also induce the formation of off-flavour such as (WOF) and sensory deteriorations in final meat products.更多还原