羊肉膻味组成及脱膻技术研究进展

本文综述了羊肉膻味的化学成分以及目前国内外常用的羊肉脱膻技术。羊肉膻味物质的化学组成以4-甲基辛酸、4-甲基壬酸等低级支链脂肪酸为主;去除羊肉膻味的方法主要有中国民间脱膻法、物理化学脱膻法、微生物脱膻法等,但目前还没有一种适用于工业化生产的有效方法。     

冷却猪肉中腐败微生物鉴定及其消长规律的研究

目的对冷却猪肉中腐败微生物进行鉴定,研究其在0～4℃条件下贮藏时的消长规律。方法采用选择性培养基对冷却猪肉中的腐败微生物进行分离培养,利用Biolog微生物自动鉴定系统对菌株进行鉴定。结果共鉴定出11株具有代表性的细菌:肠杆菌4株,假单胞菌1株,热杀索丝菌1株,不动杆菌1株,乳酸菌2株,葡萄球菌2株。冷却猪肉中腐败微生物初始菌相结构为:热杀索丝菌54.9%,肠杆菌科8.7%,假单胞菌属3.6%,乳酸菌属29.5%,葡萄球菌/微球菌0.6%,霉菌/酵母菌2.7%。在0～4℃条件下贮藏时,热杀索丝菌、肠杆菌科和假单胞菌属是冷却猪肉中的优势腐败菌,假单胞菌属和肠杆菌科在菌相结构中的比例增长最高,特别是假单胞菌属的数量增长最快。结论鉴定出了冷却猪肉中的主要腐败微生物,确定了其初始菌相和优势腐败菌。     

绵羊、牛和猪脂肪组织中挥发性脂肪酸的组成分析

为了研究不同畜种之间脂肪组织中挥发性脂肪酸的组成成分,利用同时蒸馏萃取技术和气相色谱技术对猪、牛和羊脂肪组织中的挥发性脂肪酸进行了测定.结果表明,绵羊、牛和猪脂肪组织中总挥发性脂肪酸分别为600.512、456.029、202.371 mg/kg.在猪脂肪组织中没有检测到支链脂肪酸;在牛脂肪组织中检测到了4-甲基辛酸,质量比为7.508 mg/kg,远小于羊脂肪组织中4-甲基辛酸的含量,其质量比为28.119 mg/kg;在羊脂肪组织中,检测到种类较为丰富的挥发性脂肪酸,其中对羊肉膻味起主要作用的4-甲基辛酸,在羊脂肪组织中有较高的含量,这一特征与猪和牛的挥发性脂肪酸形成显著的区别.     

乳酸菌发酵山羊肉香肠的研制

<正> 羊肉营养价值较高,兼有药膳滋补作用.但由于羊肉,特别是山羊肉有很浓的膻味,使许多人厌而废食.为开发山羊肉制品,我们开展了“乳酸菌发酵山羊肉香肠”的研制工作.经查证,羊奶中膻味物质主要与已酸、辛酸、癸酸等低碳链游离脂肪酸有关,这些游离脂肪酸以一定比例,形成某种络合物和缔合物,构成了一种膻味成分(1).公山羊脂肪腺伴随性成熟的激素可合成和分泌4—乙基辛烷酸、4—乙基癸烷酸等,这些脂肪酸污染羊奶时可增加其膻味.我们推测山羊肉的膻味可能与上述物质有一定的关系.要想除去膻味,就应该设法破坏或改变这些成分的特殊存在形式.目前国内已有采用物理的或化学的去膻方法的报导.为使去膻不致破坏肉的营养价值和风味,我们设想通过对人体有益的微生物的发酵作用,利用微生物在代谢过程中产生的各种酶来分解膻味物质,或者破坏它的特殊存在形式,达到去膻的目的.我们采用人工接种乳酸菌发酵香肠的工艺路线及科学配方,生产出了基本无膻味的山羊肉香肠,经感官鉴评,色、香、味、形比较满意,愿在此报道出来与同行共同探讨.     

德宏水牛乳饼中乳酸菌的分离鉴定及发酵性能研究

德宏水牛奶乳饼是云南特有的乳制品,微生物资源丰富,是乳酸菌的重要来源,也是分离筛选优良发酵剂的天然基础。本文采用16S rRNA基因序列分析法和纯培养法对15份水牛奶乳饼中乳酸菌种属进行分离鉴定,通过对菌株产酸、产香、发酵乳活菌计数等比较,以筛选出具有优良发酵特性的乳酸菌。结果表明:15份水牛奶乳饼样品中共分离鉴定出57株乳酸菌(3个属,6个种和1个亚种),其中Lactobacillus fermentum和Lactobacillus oris为优势菌属,占总菌属的36.84%和24.56%。57株乳酸菌发酵特性比较后得到两株优势菌株MGR3-1和MBR1-1。此研究为后续开发和应用优良发酵剂提供理论基础。     

应用于羊肉脱膻的三种发酵剂筛选及发酵特性研究

为筛选出适合发酵羊肉制品的优质发酵剂,对肉葡萄球菌（Staphylococcus carnosus）、植物乳杆菌（Lactobacillus plantarum）和戊糖片球菌（Pedicoccuspentosaceus）的发酵特性进行研究,通过耐盐、耐亚硝酸盐、产酸能力、蛋白质和脂肪分解能力、膻味脂肪酸降解能力、抑菌能力、菌种间拮抗作用等试验对其筛选。结果表明,三株菌对食盐和亚硝酸盐具有较好的耐受性,能在6%的食盐溶液和150 mg/L亚硝酸盐溶液中存活,具有一定产酸能力,除植物乳杆菌无脂肪酶活性,其他两株菌具有蛋白质和脂肪降解能力,膻味脂肪酸降解率可达60%～80%,能抑制病原微生物的生长,且三株菌间无拮抗作用,对羊肉制品的风味和品质无负面影响。因此肉葡萄球菌、植物乳杆菌和戊糖片球菌可进一步应用于发酵羊肉制品的生产和开发。     

降解多种抗生素残留的乳酸菌的筛选鉴定及特性研究

为研究和筛选高效降解抗生素残留的乳酸菌,采用高效液相色谱法与微生物学方法相结合的方式进行初步筛选,从土壤中分离获得一株乳酸菌菌株P3-4,结合菌落及菌体形态、通过Biolog自动微生物鉴定系统鉴定和16S rDNA基因序列相似性分析,鉴定菌株P3-4为乳酸片球菌（Pediococcus acidilactici）。乳酸菌P3-4在MRS培养基中具有抗生素残留降解能力,对红霉素、罗红霉素与螺旋霉素的降解率分别能达到92.1%、68.9%和82.8%。为菌株P3-4的进一步开发利用提供了理论支持。     

7 种天然发酵水果中醋酸菌的分离鉴定及其发酵特性

为筛选适合发酵果醋的优良醋酸菌,对苹果、草莓、香瓜、芒果、杏、樱桃、百香果7种天然发酵水果中的菌株进行分离,并采用生理生化试验、16S rDNA基因序列分析进行鉴定,对筛选鉴定的菌株进行耐乙醇、耐温、耐酸的发酵特性研究。结果表明,共分离得到29株菌落较大的菌株,经6 d发酵,筛选出产酸量大于30 g/L的菌株8株,并成功鉴定出8株醋酸菌。其中N8、Y21、A12、T11、C7为热带醋酸杆菌（Acetobacter tropicalis）,Y11和M8为塞内加尔醋杆菌（Acetobacter senegalensi）,S21为可可豆醋酸杆菌（Acetobacter fabarum）。N8、A12、T11、Y21在乙醇浓度为4%时,产酸量比其他菌株和醋酸菌AS1.41（商业菌株）高,最高可达到36.36 g/L。当温度为39℃时,这4株醋酸菌的产酸量也能达到10 g/L以上,能够耐受40 g/L的乙酸含量。结果表明N8、A12、T11、Y21具有良好的发酵产酸能力。     

明永冰川低温细菌分离鉴定及生物学特性

对明永冰川冰舌地区的细菌进行分离培养和鉴定。通过土壤悬浮涂布法和平板划线法分离纯化细菌,并做生理生化特性、16S rRNA基因序列测定及系统发育分析。从明永冰川地区分离纯化出22株可培细菌,16S rRNA基因序列分析结果表明:菌株MY0504与黄杆菌属梭菌(Flavobacterium pectinovorum)亲缘关系最近(97.6%);菌株MY1413和MY14015分别与Arthrobacter psychrophenolicus和Arthrobacter parietes有很近的亲缘关系(98%);MY14011与河流色杆菌(Chromobacterium fluviatile)进化关系最近(97%),其余18株菌均鉴定为假单胞菌属的菌株(Pseudomonas spp.)。作者对该地区微生物资源进行初步探究,为了解冰川低温微生物多样性提供参考。     

四种蜂蜜中脂肪酸的气相色谱-质谱分析

对湖北产荆条蜜、紫云英蜜、柑橘蜜、油菜蜜4个蜂蜜品种中的脂肪酸组成和含量进行分析比较。采用乙醚提取蜂蜜中的脂肪酸,再以硫酸-甲醇溶液进行甲酯化处理,通过气相色谱-质谱联用仪分离鉴定其中的脂肪酸组成和相对含量。结果表明,4种蜂蜜中共分离出14种脂肪酸,其中荆条蜜、紫云英蜜及油菜蜜中分别鉴定出8种脂肪酸,柑橘蜜中鉴定出7种脂肪酸,另外,14种脂肪酸中不饱和脂肪酸占总脂肪酸含量的45.53%～79.31%,饱和脂肪酸占总脂肪酸含量的16.68%～40.77%,4种蜂蜜中均含有棕榈酸和油酸。     

Fat-borne volatiles and sheepmeat odour

The effects of lamb age and diet on volatiles from fat are described. Rendered fat from ram lambs raised on ewe's milk then a corn-based diet was compared with that from lambs raised on milk and a pasture of grass/clover, six treatments in all. An additional treatment comprised very old ewes maintained on pasture. Helium-borne volatiles of rendered fat were resolved on a DB5 gas chromatographic column and the mass spectra obtained. Long chain alka(e)nes like neophytadiene were dominant in pasture treatments especially where the lamb growth rate was slow. Branch chain fatty acids (4-methyloctanoic, 4-methylnonanoic and an unidentified acid) were also highest in these treatments. Longer chain aldehydes like 2-undecenal were good indicators of a grain diet. Hexanal, commonly associated with rancid odours, was unaffected by treatment. The diketone 2,3-octanedione was an excellent indicator of a pasture diet, as was 3-methylindole (skatole). Phenols showed complex relationships to treatments, but were generally more common in pasture treatments. Benzenethiol (thiophenol) was unaffected by treatment. Inspection of principal component analysis plots identified 10 volatile compounds as contenders for the cause of sheepmeat odour; branch chain fatty acids were confirmed as the leading chemical class. There were indications that puberty or age caused an increase in the odorous 4-methylnonanoic acid. Animal odour-the odour of confined livestock-was clearly causally linked to 3-methylindole, a rumen breakdown product of tryptophan. 3-Methylindole was also responsible for rancid odour, rather than hexanal and its analogues. A hypothesis is advanced that links 2,3-octanedione formation to the enzyme lipoxygenase and linolenic acid, both abundant in green leafy tissue. Overall, the data confirm that sheepmeat odour/flavour is specifically linked to the branch chain fatty acids, and is probably exacerbated by pasture-derived 3-methylindole and alkyl phenols.     

羊肉膻味组成及脱膻技术研究进展(英文)

<正>The compounds that are responsible for the species-related characterizing flavors of mutton were reviewed,and the article also introduced some usual methods used now to reduce the odor of mutton.Short branched-chain fatty acids such as 4-methyloctanoic acid;4-methylnonanoic acid and so on were considered the main compounds that were responsible for the species-related flavors of mutton.The methods that were used to improve the flavors include Chinese traditional ways,the physical and chemical ways and microbiological ways,but,there was not an effective method to industrialized produce at present.     

Age and nutrition influence the concentrations of three branched chain fatty acids in sheep fat from Australian abattoirs

The characteristic mutton odour, associated with the cooked meat of older sheep, can be problematic for some consumers who find the odour disagreeable. Branch chain fatty acids (BCFAs) are considered to be the main determinants of mutton odour. In this study, the aim was to identify the factors influencing the BCFA content of animals at abattoirs in Australia. Samples of subcutaneous fat from over the chump (gluteus medius) were collected from 533 sheep carcasses at abattoirs in New South Wales, Victoria and Western Australia. The carcasses were from sheep differing in age, gender, breed and nutrition. The concentrations of three branched chain fatty acids (BCFAs); namely, 4-methyloctanoic (MOA), 4-ethyloctanoic (EOA) and 4-methylnonanoic acids (MNA), were determined. Statistical modelling showed that, with pre-slaughter nutrition in the model as a random term, BCFA concentrations could be used for discriminating the age of sheep. Fat samples from lamb carcasses had lower MOA and EOA concentrations and a higher concentration of MNA in comparison to hogget and mutton (P < 0.05). When nutrition was excluded as a random effect from the statistical model, the MOA and MNA concentrations did not differentiate between lamb, hogget and mutton whereas, for EOA, lamb had a lower concentration than mutton (P < 0.05) with hogget intermediate. An interaction existed between age and gender (P < 0.05) where female lambs had lower EOA concentrations relative to the mutton but not for castrates.     

The effects of antioxidative treatments on mutton flavour/odour intensity and species flavour differentiation

This study examined the effects of curing and oxygen exclusion on the odour and flavour of sheepmeats. One series of experiments examined the effect of curing on the ability of panellists to distinguish between the flavours of lean mince from various species (mutton, beef, pork, chicken). Other experiments examined the effects of curing and of maintaining an anoxic storage/cooking environment on the intensity of mutton flavour and odour, particularly adipose tissue odour. Curing had no effect on panellists' abilities to distinguish between the flavour of mince from different species. Storage and cooking of uncured mutton adipose tissue samples under anoxic conditions limited lipid oxidation but enhanced mutton odour intensity. Nitride had a pro-oxidant effect on mutton adipose tissue stored in air. There was no corresponding effect on mutton odour intensity. These findings suggest that lipid oxidation products contribute very little to mutton odour from adipose tissue, and possibly also to species flavour differences in lean meats.     

羊肉的脂肪酸组成分析及脱膻技术研究

介绍了形成羊肉膻味的化学成分,羊肉膻味与羊肉体脂肪酸的组成的关系,最后综述了目前常用的羊肉脱膻技术。     

Effect of branched-chain fatty acids, 3-methylindole and 4-methylphenol on consumer sensory scores of grilled lamb meat

Tenderness, flavour, overall liking and odour are important components of sheepmeat eating quality. Consumer assessment of these attributes has been made for carcasses from the Information Nucleus Flock (INF) of the Cooperative Research Centre for Sheep Industry Innovation. The concentrations of three branched chain fatty acids, 4-methyloctanoic (MOA), 4-ethyloctanoic (EOA) and 4-methylnonanoic acids (compounds related to ‘mutton flavour’ in cooked sheepmeat) and 3-methylindole and 4-methylphenol (compounds related to ‘pastoral’ flavour) were determined for 178 fat samples taken from INF carcasses. Statistical modelling revealed that both MOA and EOA impacted on the ‘Like Smell’ consumer sensory score of the cooked meat product (P < 0.05), with increasing concentration causing lower consumer acceptance of the product. None of the compounds though had an effect on the liking of flavour. Obviously, reducing the effect of MOA and EOA on the odour of grilled lamb will improve consumer acceptance of the cooked product but other factors affecting the eating quality also need to be considered.     

顶空固相微萃取结合气质联用技术结合相对气味活度值对甘肃细毛羊肉特征挥发性风味物质的研究

为研究河西地区肃南甘肃高山细毛羊肉的挥发性风味物质,采用顶空固相微萃取(HS-SPME)结合气质联用(GC-MS),对其挥发性风味物质进行检测,通过相对香气活度值,确定了甘肃高山细毛羊肉关键性挥发性风味物质。结果显示,甘肃高山细毛羊肉中共检测到43种挥发性化合物,占总离子峰的88.16%。主要为醛、醇、酮、酯、酸、烷烃及酚类,相对含量分别为30.65%、10.57%、27.62%、17.94%、5.85%、2.19%和1.44%,未检测到体现膻味的物质4-甲基辛酸和4-甲基壬酸。采用相对香气活度值确定了5种关键性挥发性香气成分为3-羟基-2-丁酮、gamma-丁内酯、1-辛烯-3-醇、辛醛、己醛。甘肃高山细毛羊肉挥发性风味物质含量丰富,是风味较佳的畜产品,为甘肃高山细毛羊肉的加工提供一定的科学依据。