鱿鱼皮胶原蛋白肽的脱色及其对风味影响的研究

为探究脱色工艺及其对鱿鱼皮胶原蛋白肽风味的影响,本试验在酶解制备的基础上,研究了不同活性炭和树脂对鱿鱼皮酶解液的脱色效果及最优工艺,并采用电子舌、电子鼻、氨基酸分析及感官评价等方法对鱿鱼皮胶原蛋白肽风味变化进行了分析。结果表明,粉末状活性炭的脱色效果较好,最佳脱色工艺为：pH值2.0,添加量0.1%(m/v),30℃下脱色30 min,该条件下鱿鱼皮酶解液的脱色率和蛋白损失率分别为82.91%和24.81%。分子量分布与游离氨基酸分析结果表明,与脱色前相比,脱色后样品的分子量分布变化不大,游离氨基酸及苦味氨基酸含量下降,鲜味氨基酸占比上升。电子舌、电子鼻及感官评价结果表明,脱色前后样品的风味差异较大,脱色后,样品的风味有显著改善,表现为苦味下降,鲜、酸、咸味提升。本研究结果为鱿鱼皮高附加值产品的开发及胶原蛋白肽的应用提供了一定的理论依据。     

接种贝莱斯芽孢杆菌SW5菌株对发酵鳀鱼鱼露品质的影响

为探讨接种贝莱斯芽孢杆菌SW5菌株对发酵鳀鱼鱼露的影响,以贝莱斯芽孢杆菌SW5为唯一发酵菌株,以低值鳀鱼为原料,测定鱼露发酵过程中氨基酸态氮(AA-N)、挥发性盐基氮(TVB-N)、pH值、总酸含量,并使用顶空固相微萃取结合气相色谱-质谱联用仪(HS-SPME-GC-MS)测定发酵结束后发酵液的挥发性风味物质。结果表明,在发酵期间,利用SW5菌株发酵的处理组1在发酵第6天时AA-N含量最高,为0.76 g·100 mL^-1,达到市售二级鱼露标准。3种处理组和舟山商品鱼露中共检测出挥发性风味成分82种,主要是醇、酸、醛、酮、呋喃、烷烃及其他类化合物,接种组中的挥发性风味物质(40种)较未接种组(35种)有所增加。综上,接种贝莱斯芽孢杆菌SW5菌株发酵鱼露,能缩短发酵时间,增加风味物质种类,该菌株可用作海洋蛋白质源发酵精深加工的优良微生物菌株。     

不同品种毛豆脆粒挥发性物质组成及差异分析

采用顶空固相微萃取(HS-SPME)和气相色谱-质谱(GC-MS)联用技术鉴定了6种毛豆脆粒挥发性物质组成,结合感觉阈值,利用相对风味活度值(ROAV)确定了各品种主体风味成分,并运用主成分分析(PCA)探讨了不同品种毛豆脆粒主要风味物质差异。结果表明,6种毛豆脆粒共检测出65种挥发性成分,主要包括醛类、醇类、酮类和烃类,且各品种间挥发性组分差异较大;毛豆脆粒共有的主体风味物质为戊醛、己醛、辛醛、壬醛、1-辛烯-3-醇、1-辛烯-3-酮和柠檬烯,3-甲基丁醛为新大粒1号和通豆5号脆粒特有的主体风味物质。通过不同品种主要风味物质的PCA分析可知,戊醛、顺-2-庚烯醛分别是苏豆3号、淮豆8号脆粒区别于其它品种的标志性风味物质。各品种毛豆脆粒主体风味物质间交互作用影响其总体风味。本研究为毛豆脆粒风味品质评价提供一定指导。     

大豆品种对毛霉豆豉传统发酵过程中营养成分的影响

以重庆本地大豆和东北大豆为原料进行传统毛霉豆豉的制作,研究2种豆豉发酵过程中营养成分的变化。结果表明:2种豆豉在发酵过程中水分和总酸含量变化趋势相似;本地大豆蛋白质含量高于东北豆,在发酵过程中随着蛋白质的水解,其含量开始下降;2种大豆在发酵过程中氨基酸态氮呈先下降后上升的趋势,其中重庆本地大豆制作的豆豉成品的氨基酸态氮含量远远高于东北大豆,这说明本地大豆的蛋白水解程度更高,所产生的鲜味物质较多,其营养物质更易于被人体吸收。     

电渗析技术在大豆低聚糖溶液脱盐上的应用

从甜浆中提取的大豆低聚糖粗提液中含有很多的盐类,影响糖液的纯度。该试验通过离子交换膜辅助的电渗析法对大豆低聚糖模拟溶液进行脱盐处理,确定了较好的试验操作参数。试验结果表明:电渗析法对大豆低聚糖模拟液进行脱盐是可行的,且脱盐效果较好,脱盐率达到96.07%;该试验条件下较佳的工作电压为20 V,流量为60 L/h,样品稀释倍数为15倍。通过以上条件处理后,大豆低聚糖的保留率达到83.82%。     

排水暗管间距对滨海盐土淋洗脱盐效果的影响

为合理设计盐碱土灌排改良工程,提高盐碱土改良效果,该文通过田间试验,研究了排水暗管间距对滨海盐土淋洗脱盐效果的影响。结果表明,漫灌淋洗期间,吸水管间距埋设越小,小区暗管系统稳定排水流量越大,淋洗初期的排水矿化度也越大,排水排盐效率越高;相同淋洗用水量下,3m间距小区田间各点土壤脱盐比较均一,6、9m间距小区田间各点土壤脱盐效率相差较大,3次淋洗后3个小区田间各点0~1m深土体土壤脱盐率分别在70.93%～73.40%、64.68%～77.47%、56.54%～78.78%;利用暗管工程技术参数估算方法预测了淋洗改良后田间各点土壤含盐量,不同间距吸水管上方0~1m深土体土壤含盐量预测值与实测值差异较大,其他各点差异较小,预测误差率在±10%左右。排水暗管间距对田面各点土壤脱盐效果影响很大,盐碱土灌排改良应合理设计暗管间距和采取有效的淋洗措施。     

组合酶水解鸡骨素工艺研究与水解液风味分析

本文用木瓜蛋白酶和风味蛋白酶进行组合,以得到组合酶水解鸡骨素的最佳工艺。首先通过正交实验确定同时加酶时风味蛋白酶和木瓜蛋白酶的适宜加酶量和水解温度,然后研究在适宜条件下,风味蛋白酶和木瓜蛋白酶的不同添加方式对鸡骨素水解效果的影响。结果表明:在料液比1∶3、温度40℃、pH值7.0的条件下先加1500U.g-1的木瓜蛋白酶水解2 h,灭酶后再加1200 U.g-1的风味蛋白酶水解2 h得到的鸡骨素水解液的水解度最高为28.8%,氮回收率为79.37%,蛋白表面疏水性指数最低。通过固相微萃取气象色谱质谱法(SPME-GC-MS)对水解液挥发性物质进行分析共检测出26种挥发性物质,吡嗪类含量最高达到41.94%,其中主要的风味物质为2,3,5-三甲基吡嗪(24.01%)和2,5-二甲基吡嗪(14.59%),醇类次之含量为21.83%,烃类含量18.09%,还有少量的醛类、酮、酚等。     

不同类型生鲜鸡对白切鸡风味的影响

为研究不同类型的生鲜鸡加工的白切鸡在风味方面的差异,探讨能否用冷鲜鸡、冷冻鸡替代热鲜鸡制作白切鸡,以热鲜(约15℃)、冷鲜(0~4℃)和冷冻(-18℃)3种不同类型的雪山黄母鸡胴体为原料,进行不同处理后用传统制作工艺加工成白切鸡,通过测定处理后白切鸡的挥发性风味物质、pH值、有机酸含量、呈味核苷酸含量和游离氨基酸含量等研究其风味差异。结果表明,冷鲜4个处理组与热鲜2 h组、热鲜4 h组的肌苷酸(IMP)、总游离氨基酸含量无显著差异,但重要挥发性风味物质(如醛类)和丁二酸含量高于热鲜2 h组和热鲜4 h组;热鲜1 h组的IMP含量显著高于冷鲜处理组(P<0.05),但其重要挥发性风味物质含量低于大部分冷鲜组;冷冻60 d组和冷冻90 d组除己醛含量显著高于其他处理组,其他挥发性风味物质、滋味物质含量均较低。综上,冷鲜鸡和短期冷冻鸡在总体上可以替代热鲜鸡制作白切鸡,这为白切鸡工业化生产发展提供了理论支持。     

农田耕作与土壤盐分的变化

采用原状土隔离池进行了盐分运移的定位试验。结果表明：含盐量0.11-0.28%的轻盐渍化或脱盐潮土处在不断脱盐过程中，平均年脱盐速率为0.0125%；小麦种植期，土壤处于返盐过程，盐分在上层积累；夏玉米种植期，土壤处于脱盐过程；盐分运动是一个盐离子的层次间传递过程，不同盐离子传递的强度不同，以氯根和纳离子变动最大，而硫酸根和钙离子变幅较小，碳酸根较稳定。     

四种有机废弃物对新疆盐碱地及甜菜苗期生长的影响

为探明4种有机废弃物及施用量对甜菜苗期生长及土壤盐分的影响,采用盐碱土开展甜菜盆栽试验,施用不同浓度味精废弃物、加菌味精废弃物、沼液、动物氨基酸,以清水为对照,观测盆栽土壤的pH值、盐分及甜菜苗期生长指标。结果表明,施用沼液与动物氨基酸能降低土壤的pH值,施高浓度沼液的土壤pH降值1.46个单位,效果明显;施用150 g·m~(-2)味精废弃物与加菌味精废弃物能明显降低土壤盐分,脱盐率分别达到33%、31%;同时150 g·m~(-2)加菌味精废弃物能显著提高发芽质量,发芽率达到88%,活力指数较对照增加3.59;施用50 g·m~(-2)动物氨基酸能有效促进甜菜生长,干物质较对照增重3.95 g。研究结果可为高效利用有机废弃物改善新疆盐碱地与甜菜生长环境提供参考。     

Low molecular weight compounds responsible for savory taste of Indonesian soy sauce

Indonesian soy sauce is made using only soybeans as the nitrogenous source. Moromi obtained from fermentation of yellow soybeans using Aspergillus sojae as the starter was investigated. The fraction with molecular weights of less than 500 Da obtained by stepwise ultrafiltration was then fractionated by several chromatographic procedures, including gel filtration chromatography and RP-HPLC. Several chemical analyses, CE profiles, and taste profiles were performed to obtain the most intense umami fraction. The main components eliciting or enhancing the umami taste present in the fraction were purified and identified by protein sequencing, ESI-MS, and (1)H NMR at 400 MHz. Besides free l-glutamic acid and aspartic acid, free aromatic amino acids such as l-phenylalanine and l-tyrosine may also play an important role in impressing savory or umami taste of Indonesian soy sauce at their subthreshold concentrations and in the presence of salt and free acidic amino acids. This is reported as a new phenomenon of the so-called bitter amino acids.     

鱼粉加工压榨液经酶解发酵后的风味变化

为实现鱼粉加工副产物的高值化利用,本研究对鱼粉加工压榨液经酶解发酵后的挥发性风味及游离氨基酸含量进行了分析。结果表明,鱼粉加工压榨液经酶解发酵后,其滋味成分、游离氨基酸含量、呈味强度和呈鲜能力明显增加,且其牛磺酸含量高达0.263 g·100mL^-1,远高于市售鱼露。挥发性风味分析表明,酶解和发酵显著改善了鱼粉加工压榨液的风味,其醛醇类化合物、吡嗪类以及含硫类化合物含量均有所增加,酮类物质含量下降,其风味与市售鱼露相当。本研究为鱼粉加工压榨液或其他水产品下脚料的综合利用提供了有效手段。     

Transcriptome profiling of heat-resistant strain Bacillus licheniformis CGMCC3962 producing Maotai flavor

Although Maotai flavor liquor is exclusive due to its soy sauce flavor, knowledge of its key compound and production mechanism is still scarce until now. To gain insight into the production mechanism of soy sauce flavor, a soy sauce flavor producing strain with high efficiency and heat-resistant capability was obtained, and the metabolic mechanism of the strain was investigated with the technique of microarray profiling. Because high temperature was a key factor for soy sauce flavor production, the global gene expression of this heat-resistant strain fermented at 55 °C was analyzed. Except for the responsive increase of heat shock proteins, which maintained cell survival during heat stress, biosynthesis of cysteine was also up-regulated. In addition, some metabolites were significantly increased when cysteine was added to the fermentation medium, such as 2,3-butanediol, 3-hydroxy-2-butanone, and tetramethylpyrazine, which were important flavor compounds in soy sauce flavor liquor and might be related with soy sauce flavor. The results indicated that cysteine might play an important role in the formation of soy sauce flavor compound, and it might act as an indirect precursor or stimulator of soy sauce flavor formation. This was the first use of the microarray profiling tool to investigate the fermentative strains for Chinese traditional liquor, which would allow a deeper insight into the mechanism of the formation of soy sauce flavor compound.     

Use of Tetragenococcus halophilus as a starter culture for flavor improvement in fish sauce fermentation

The potential of Tetragenococcus halophilus as a starter culture for flavor improvement in fish sauce fermentation was elucidated. Four strains of T. halophilus isolated from fish sauce mashes were inoculated to anchovy mixed with 25% NaCl with an approximate cell count of 10(6) CFU/mL. The α-amino content of 6-month-old fish sauce samples inoculated with T. halophilus was 780-784 mM. The addition of T. halophilus MRC10-1-3 and T. halophilus MCD10-5-10 resulted in a reduction of histamine (P < 0.05). Fish sauce inoculated with T. halophilus showed high contents of total amino acids with predominantly high glutamic acid. Major volatile compounds in fish sauce were 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, and benzaldehyde. T. halophilus-inoculated fish sauce samples demonstrated the ability to reduce dimethyl disulfide, a compound contributing to a fecal note. The use of T. halophilus for fish sauce fermentation improves amino acid profiles and volatile compounds as well as reduces biogenic amine content of a fish sauce product.     

Characteristics of salt-fermented sauces from shrimp processing byproducts

A salt-fermented sauce from shrimp processing byproducts (heads, shells, and tails) was prepared and characterized. Three types of sauces were prepared; sauce C, with 30 g of salt/100 g of byproduct (high salt); sauce E, with 30 g of salt and 0.2 g of sodium erythorbate (high salt); and sauce L, with 20 g of salt, 0.2 g of sodium erythorbate, 6 g of sorbitol, 0.5 mL of lactic acid, and 5 mL of ethanol (low salt). Sauces C and E showed higher exopeptidase activities than sauce L, whereas sauce L showed the highest endopeptidase activity. After 3 months of fermentation, the amino N content of sauce increased from 150-200 to 500-600 mg/100 g and the nonprotein nitrogen content increased from 300 to 950-1050 mg/100 g. Volatile basic nitrogen content increased significantly from 18 to 60 mg/100 g. The total carotenoids retained in sauces C, E, and L were 26.3, 76.2, and 73%, respectively, thus indicating that the addition of sodium erythorbate to sauces E and L retarded oxidation. Water activities of sauces C, E, and L were 0.753, 0.751, and 0.773, respectively. According to the omission test, the taste of sauces was influenced by the content of free amino acids, mainly glutamic acid and aspartic acid. All three sauces examined showed a 35% higher total amino acid content than commercial salt-fermented shrimp sauces. Therefore, shrimp processing byproducts may lend themselves to the preparation of high-quality salt-fermented sauces.     

贮藏温度对三疣梭子蟹蟹肉风味的影响

为延缓三疣梭子蟹品质劣变,延长其货架期,本试验研究了冰温贮藏、冷藏、冰藏对蟹肉挥发性风味、腺苷三磷酸(ATP)关联物及游离氨基酸含量的影响,并对其呈味物滋味强度值(TAV)及味精当量(EUC)进行分析。结果表明,冰温组蟹肉挥发性风味在贮藏前6 d 无明显变化,而冷藏和冰藏组蟹肉挥发性风味分别在贮藏第2和第4 天开始出现明显变化。冰温组蟹肉肌苷酸(IMP)和腺苷酸(AMP)的滋味强度值、游离氨基酸总量、鲜味氨基酸、甜味氨基酸和甜苦味氨基酸占总游离氨基酸的百分比、EUC均高于同期冰藏、冷藏。组综上所述,冰温贮藏能有效保持蟹肉良好风味,缓解蟹肉风味劣变。本研究结果为冰温贮藏技术在梭子蟹保鲜中的应用提供了一定的理论依据。