蒸制过程中鲣鱼背肉的品质及风味变化

以鲣鱼的背部肌肉为原料,通过测定其质量损失率、pH、质构特性、肌原纤维蛋白、肌浆蛋白含量、水分分布、游离氨基酸含量、挥发性风味物质以及人工感官评定分析蒸制过程中的品质和风味的变化。结果表明,蒸制过程中的质量损失率在0～6 min迅速上升后趋于稳定、pH整体呈上升趋势,硬度显示两个波峰,在蒸制8 min时的弹性达到2.20 mm,肌原纤维蛋白、肌浆蛋白含量在0～6 min内显著下降（P<0.05）后趋于稳定,不易流动水含量不断下降,自由水含量先升高后降低。呈鲜甜味的谷氨酸含量、游离氨基酸总量随蒸制时间的变化趋势相同,整体呈现先升高后降低的趋势,游离氨基酸总量在蒸制6 min和8 min时总量分别为3369.03 mg/100 g、3438.76 mg/100 g。GC-MS分析结果显示,蒸制过程中呈腥味的庚醛和壬醛的相对含量逐渐降低,且在蒸制8 min的相对含量仅为1.14%和1.69%,去腥效果最好。人工感官分析也表明蒸制8 min时的整体评分最佳。因此选用蒸制6～8 min的条件获取到的鲣鱼鱼块的品质及风味最佳。     

蒸制面条工艺优化的研究

加工工艺是影响蒸制面条品质的关键因素。本文以质构品质和感官评分为指标,考察了加水量、加盐量、和面时间、醒发时间对蒸制面条品质的影响。在此基础上,通过正交实验对蒸制面条加工工艺进行了优化,并借助扫描电镜观察了蒸制面条微观结构。结果表明,加工蒸制面条的最佳工艺条件为:和面时间15 min,加水量28%、加盐量0.4%、醒面时间10 min,此时,蒸制面条的感官评分为86.8±0.80、硬度为(7740.53±76.88)g、咀嚼度为(6628.19±122.48)g。面条经蒸制后,淀粉颗粒膨胀糊化,较好的镶嵌在蛋白质网络中,与蛋白质结合更紧密。      

不同品种山药蒸制过程中淀粉消化率及抗氧化活性

本实验以不同品种山药的淀粉相关特性、生物活性成分、抗氧化能力和微观结构为评价指标,研究蒸制时间对铁棍山药、淮山药、糯山药3种山药的营养品质和抗氧化活性的影响,并探究山药微观结构和品质变化的内在联系。结果表明,蒸制处理后,3种山药样品中的总淀粉质量分数和抗性淀粉质量分数均显著减少（P<0.05）,但可消化淀粉（快消化淀粉和慢消化淀粉）及表观直链淀粉质量分数显著增加（P<0.05）,同时山药淀粉的持水力增强,溶解度下降。3种山药中,蒸制15 min的淮山药总可溶性多酚和总黄酮含量最高,分别为1.04 mg/g和0.83 mg/g,同时,其抗氧化能力也最强,铁离子还原力、1,1-二苯基-2-苦基肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除率和羟自由基清除率分别为165.56?μmol/g、58.15%和82.26%。扫描电子显微镜观察发现,蒸制后山药样品颗粒呈特征性的块状和不规则的结构,表面粗糙并有裂缝。综合比较,蒸制时间对3种山药样品的品质特征及活性成分的影响差异较大,蒸制15 min后山药样品的总可溶性多酚和总黄酮含量最高,抗氧化活性也...     

海鲈鱼肉蒸制过程中品质及风味特性的变化

以海鲈鱼背部肌肉为原料,对不同蒸制时间鱼肉的质量损失率、色泽、水分分布状态和质构特性变化进行分析,并通过游离氨基酸分析、电子舌和电子鼻评价鱼肉的滋味和气味差异。结果表明,随着蒸制时间的延长,海鲈鱼肉的质量损失率显著上升（P＜0.05）,鱼肉中的不易流动水逐渐向自由水转化并流失,而结合水含量变化不明显;鱼肉的硬度和咀嚼度先下降后又显著增大,而弹性先升高后降低;蒸制后鱼肉的L*值和b*值显著升高（P＜0.05）,a*值显著降低（P＜0.05）。经蒸制后鱼肉中游离氨基酸的总量先增大后降低,在蒸制10 min达到最高值,组氨酸、甘氨酸、丙氨酸、赖氨酸和谷氨酸是海鲈鱼肉中主要的呈味氨基酸;电子舌和电子鼻均能有效区分不同蒸制时间鱼肉的滋味和气味特征。综上,限定规格的海鲈鱼块在蒸制8～10 min的品质及风味较好。     

南美白对虾蒸制过程中水分状态及质构的变化

研究南美白对虾在蒸制过程中的水分状态和质构变化,以及虾肉组织结构对其的影响。采用直接干燥法分析虾肉水分含量的变化,水分活度仪、低场核磁共振仪(LF-NMR)研究虾肉水分活度和水分状态,质构仪分析虾肉硬度、咀嚼度、回复性和黏聚性变化,V.G.染色法观察虾肉组织结构的变化。结果表明:随着蒸制时间的延长,虾肉水分含量、Aw下降;结合水和中间水含量变化不显著,而自由水含量显著降低;硬度、咀嚼度、回复性和黏聚性升高;肌肉纤维收缩和聚集,肌纤维束间的空隙逐渐加大,造成流动性最强的自由水损失,虾肉质构发生变化。     

蒸制过程中馒头坯蛋白质变化特性研究

研究馒头坯在蒸制过程中蛋白质各组分含量、蛋白质二级结构、游离巯基和二硫键含量、蛋白质分子质量以及蛋白质体外消化率的变化.结果表明:随着蒸制的进行,馒头坯中总粗蛋白含量基本不变,清蛋白、球蛋白、醇溶蛋白、SDS可溶性麦谷蛋白的含量呈现显著下降趋势,麦谷蛋白大聚体含量呈现显著上升趋势;蛋白质二级结构中α-螺旋和β-折叠含量...     

牦牛肉发酵过程中的品质变化分析

为了解牦牛肉在发酵过程中的风味等品质特征差异,本试验选取斯布牦牛和甘南牦牛两种品系的半腱肌为研究对象,测定发酵过程中食用品质及风味物质的特征。研究发现,发酵过程中肉色逐渐加深,两品系牦牛肉L*值在第5天均达到最大值后逐渐降低;斯布牦牛肉硬度发酵后较发酵前下降32 543.35 g,弹性增大2.573 mm,咀嚼性降低8 912.89 mJ,甘南牦牛肉硬度发酵后较发酵前下降28 668.6 g、弹性增大2.041 mm、咀嚼性降低6 685.51 mJ。斯布牦牛发酵肉中检出18种主要风味物质,甘南牦牛发酵肉中检出21种主要风味物质。两品系发酵牦牛肉中主要风味物质有烯、醇、醚和醛类,赋予发酵肉特有的清香、脂类等特征风味。     

南美白对虾冷风干燥过程中的品质变化研究

冷风干燥是一种重要的水产品干燥方法。该文主要研究南美白对虾在冷风干燥过程中水分含量、复水率、质地、微观结构、色泽及感官评分的变化。结果表明:随着干燥时间的延长,南美白对虾水分含量逐渐降低,复水率显著增加;硬度、咀嚼度不断增大;肌纤维聚集,纤维束间空隙逐渐变大,但干燥16 h的样品仍保持较为完整的纤维结构;冷风干燥16 h时,虾的a~*值达到最大,色泽最红,咀嚼性好,风味浓郁,感官评分最高。     

低盐腌制草鱼肉各分割部位蒸制过程品质变化规律

目的：揭示不同蒸制时间对添加1.5%食盐腌制草鱼肉(Ctenopharyngodon idellus)不同分割部位食用品质的影响,并评价其加工适宜性。方法：将草鱼肉分割为4个部分,包括背部、腹部、腩部和尾部,并用1.5%食盐湿腌30 min,通过得率、色泽、感官评分、三磷酸腺苷(adenosine triphosphate,ATP)关联产物、蛋白质消化率和分子质量分布对2 100 W下蒸制6、9、12 min的各部位鱼肉进行研究。结果：与蒸制6、12 min相比,蒸制9 min的背部和腹部肉的蛋白质消化率显著最高(P<0.05)。与蒸制12 min相比,尾部肉在蒸制6 min时感官总评分和肌苷酸(inosine monophosphate,IMP)含量均显著较高(P<0.05)。随着蒸制时间的延长,尾部肉的感官总评分显著降低、色泽显著劣变,表现为过红、过黄(P<0.05),食用品质明显下降。蒸制12 min时腹部和腩部肉的红度值(a^*)和黄度值(b^*)显著高于相同蒸制时间下的背部和尾部(P<0.05),食用品质严重降低...     

鲤鱼鱼鳞蛋白酶解液对鲤鱼肉冷藏期间品质变化的影响

为研究鲤鱼鱼鳞蛋白酶解液对鲤鱼肉冷藏期间品质的影响,本文以新鲜鲤鱼肉为研究对象,将鱼肉分别在不同浓度鲤鱼鱼鳞蛋白酶解液(0.01、0.03、0.04 g/mL)作浸渍处理(无菌水浸渍处理为对照组),置于4 ℃条件下贮藏,在0、2、4、6、8、10 d进行各组样品的菌落总数、可溶性蛋白含量、蒸煮损失率、汁液流失率、硫代巴比妥酸(thiobarbituric acid,TBA)值、酸价、总巯基与游离巯基含量等指标测定。结果得出,经鲤鱼鱼鳞蛋白酶解液处理后鲤鱼肉样品,各浓度处理组的总巯基与可溶性蛋白含量的降幅均缓于对照组,且游离巯基含量、TBA值、汁液流失率、蒸煮损失率与酸价值的增幅不大。其中,对照组样品在第6 d时的菌落总数超过二级鲜度,而处理组样品在第10 d时仍处在二级鲜度(4.01~6.01lg CFU/g)。并且0.03 g/mL鲤鱼鱼鳞蛋白酶解液的处理效果最佳,使鲤鱼鱼肉的保藏期延长4 d。说明鲤鱼鱼鳞蛋白酶解液能有效减缓鲤鱼肉冷藏期间的脂肪与蛋白质氧化。     

不同温度对白鲢鱼肉在蒸煮过程中品质的影响

为了研究蒸煮过程中温度对白鲢鱼品质的影响,在常压蒸汽加热下分别测定了温度（20、30、40、50、60、70、80、90℃）对白鲢鱼肉挥发性化合物、蛋白质组分、ATP酶（Ca2+-ATPase）活性、总巯基和活性巯基含量、表面疏水性、失重率、剪切力和p H的影响。结果表明:在60℃时挥发性化合物种类最多为29种,70℃时最少为15种;醇类和烃类物质的含量分别在90和80℃时最高,醛酮类在70℃时最高;水溶性、盐溶性和碱不溶性蛋白、总巯和ATP酶活性随温度的升高而显著（p<0.05）下降。碱溶性蛋白、失重率和p H则随温度的升高而显著（p<0.05）增加。活性巯基和表面疏水性则随温度的增加而先升高后下降,分别在50℃和60℃时达到最大值0.18 mol/g和410.08 So ANS。剪切力在加热初期（20³0℃）显著（p<0.05）降低,到60℃时达到最低值114.39 g。研究结果为白鲢鱼热加工品质控制提供参考。      

Changes in the lipid components of minced carp (Cyprinus carpio) following cooking

The changes in weight, moisture, lipid content and composition, thiobarbituric acid (TBA) and carbonyl values were determined in minced carp following cooking by baking and deep-frying. Baked samples lost lipid via drip while the deep-fried samples absorbed oil. Free fatty acids decreased following cooking. Thiobarbituric acid (TBA) values increased following cooking by either method. Antioxidants (TBHQ and BHA) inhibited the production of TBA-reactive compounds though the production of carbonyls during deep-frying was enhanced. Tertiary butylhydroquinone (TBHQ) was slightly more effective than BHA in inhibiting the formation of TBA-reactive compounds.     

A mechanistic model for the uptake of waterborne strontium in the common carp (Cyprinus carpio L.)

The release of radioactive strontium to the environment is of concern due to the strong accumulation of this calcium resembling element in the bone and other tissues. To predict the effects of changes in environmental conditions on the uptake of Sr2+ and Ca2+ by freshwater fish, a Michaelis-Menten type model is introduced that accounts for the effects of chemical speciation, hydrogen ion activity, and metal ion competition. The uptake kinetics were characterized in vivo from short-term exposure experiments using the common carp (Cyprinus carpio) as the model organism. Fish were exposed to a wide range of waterborne Sr2+ (0.2-10,000 microM) and Ca2+ (10-10,000 microM) concentrations and water pH (5.0-8.5). Strontium uptake by the whole body of fish increased with increasing Sr2+ activity, displaying saturation kinetics, but decreased significantly with increasing Ca2+ and H+ activities in the water. Likewise, calcium uptake by the fish decreased with increasing Sr2+ and H+ activities in the water. The model fitted to the pooled data explains 97.5% of the variation in Sr2+ uptake and 86% in Ca2+ uptake over the wide range of exposure conditions and reveals that Sr2+ and Ca2+ inhibit each other completely competitively, while H+ inhibits the uptake of both metal ions in a partially noncompetitive way. This model can be used as a mechanistic tool to predict the uptake of these metals in carp under variable conditions.     

The effect of selenium on antioxidant system in erythrocytes and liver of the carp (Cyprinus carpio L.)

The effect of selenium‐supplemented diet (sodium selenate and selenium yeast) on antioxidant in erthrocytes and liver of the carp (Cyprinus carpio L.) fingerlings was studied. With this goal, the activities of glutathione peroxidase (GSH‐Px), catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR) and glutathione‐S‐transferase (GST), as well as glutathione (GSH + GSSG) level, were determined. In the group supplemented with sodium selenate, no significant changes in the activity of the above enzymes were recorded in both the erythrocytes and in the liver, with the exception of GST activity that was significantly reduced in the plasma compared with the controls. Glutathione content was at the control level. In the group supplemented with selenium‐yeast, the activities of GSH‐Px, CAT, and SOD were significantly increased in erythrocytes, whereas GST activity and plasma content of GSH + GSSG were reduced compared with the controls. At the same time, the activities of hepatic SOD and GST were increased compared with the controls. These results demonstrate that organically bound selenium (selenium‐yeast) acts more efficiently on antioxidant system of the carp fingerlings than inorganic selenium salts.     

Post-thawing quality changes of common carp (Cyprinus carpio) cubes treated by high voltage electrostatic field (HVEF) during chilled storage

In recent years, high voltage electrostatic field (HVEF) technology has been demonstrated to be a viable alternative to high-temperature treatments in processing for inhibiting microbial growth and maintaining post-thawing quality of foods. In this study, common carp (Cyprinus carpio) meat cubes were treated with HVEF, and compared to air-thawed and running tap water-thawed controls to investigate how HVEF affects common carp meat quality after thawing and low-temperature storage (4 °C). The results showed that thawing under − 6, − 12 kV HVEF and running tap water significantly decreased the thawing time by 30, 50 and 45 min, respectively, compared to air thawing control. In addition, − 12 kV HVEF treatment also reduced the moisture loss, which the initial drip loss of it was lower by 2.95% than CK. The initial total viable counts, Aeromonas, Pseudomonas, and lactic acid bacteria were 3.58, 3.15 2.88 and 3.25 log CFU/g in CK after thawing, respectively, which were higher than that in the cube thawed by − 12 kV HVEF (3.11, 2.93 2.71 and 2.91 log CFU/g). Additionally, − 12 kV HVEF treatment enhanced adenosine monophosphate deaminase (AMP-deaminase) activity, reduced acid phosphatase (ACP) activity and delayed the degradation of inosine monophosphate (IMP) to hypoxanthine (Hx). These results suggested that HVEF treatment could be useful in the thawing and storage of frozen common carp fish.Industrial relevanceThe study investigated the effects of high voltage electrostatic field (HVEF) thawing on the water-holding capacity, adenosine triphosphate degradation and microbial community changes of frozen common carp (Cyprinus carpio) cubes when stored at 4 °C. HVEF under − 12 kV was found to have positive influence on reducing the thawing time, maintaining water-holding capacity, decreasing the level of microbe, and delaying adenosine triphosphate (ATP) degradation. A potential application for HVEF in the thawing and storage of frozen aquatic product was highlighted in food industry.     

Effect of silver carp (Hypophthalmichthys molitrix) muscle hydrolysates and fish skin hydrolysates on the quality of common carp (Cyprinus carpio) during 4 °C storage

Silver carp (Hypophthalmichthys molitrix) skin and muscle were hydrolysed, respectively, and then used as part of an edible coating to preserve fish. The effects of muscle and skin hydrolysates as edible coatings for shelf life extension of common carp (Cyprinus carpio) were evaluated over 18 days at 4 °C, by comparing these two treatments, a chitosan coating with muscle hydrolysate, chitosan alone, and an untreated control. All coatings were made up with 5% glycerol. The quality of the carp was assessed by using total volatile basic nitrogen (TVB‐N), total viable counts (TVC), thiobarbituric acid (TBA) and K value. Compared with the control group, the rate of increase in TVB‐N, TVC, TBA and K value of carp coated with fish skin hydrolysates, fish muscle hydrolysates and chitosan added to fish muscle hydrolysates were lower. According to the total viable counts, the storage life of fish with fish skin hydrolysates coatings and chitosan added fish muscle hydrolysates coatings were 16 days, 2 days longer than those with the chitosan coatings and twice as long as the control group.