鲢鱼皮明胶提取方法和谷氨酰胺转氨酶改性对明胶结构和膜性能的影响

研究鲢鱼皮明胶的酶法、酸法、热水法3种常用的工业提取方法对其凝胶强度、黏度以及膜性能指标的影响,在此基础上进一步使用谷氨酰胺转氨酶(transglutaminase,TG)改性以达到改善膜性能的效果。同时以市售猪皮明胶为对照,采用圆二色谱、红外光谱分析3种提取方法对明胶高级结构的影响;通过红外光谱、原子力显微镜分析了鲢鱼皮明胶TG改性前后明胶高级结构和表面结构变化。结果表明,3种提取方法中酶法明胶的比黏度和凝胶强度最大,成膜后的酶法明胶膜抗拉强度最大、断裂延伸率最大、水蒸气透过率最低。继续经过TG改性后,抗拉强度、断裂延伸率指标显著增加(P0.05),接近猪皮明胶膜,水蒸气透过率进一步降低。圆二色谱及红外光谱结果发现酶法明胶α-螺旋相对含量增加、无规卷曲相对含量减少,并可保留更多的分子内氢键。而TG改性后明胶分子内氨基转变为亚氨基,同时增强了肽链间相互作用。原子力显微镜图像分析结果证明,TG改性的明胶膜具有更为致密均匀的表面结构。明胶膜的机械强度与明胶结构中α-螺旋的含量呈正相关。因此,酶法提取并通过TG改性是一种提高可食性明胶膜性能的有效方法。     

Effect of antioxidant activity of mixture obtained from brown seaweed and wheat germ oils using different extraction methods

The objective of this study was to determine the physicochemical and nanostructural properties of the alkali pre-treated gelatin from 3 different body parts (skin, muscle, and bone) of cornet fish (Fistularia petimba). The maximum yield of protein and viscosity was obtained in bone than other parts and Fourier transform infrared (FTIR) spectroscopy was carried out to characterize the extracted gelatin. Prior to extraction, the proximate composition was investigated clearly and the percentage of protein (15.50–29%), ash (4.32–6.50%), moisture (71.85–79.20%), and lipid (0.36–1.38%) content were estimated. Morphology of alkaline gelatin extracted from skin, muscle, and bone were studied using atomic force microscopy (AFM). The AFM images represented the scanning was done at 1.9 μm, 510, and 110 nm for skin, muscle, and bone, respectively showed the separate individual aggregates and the nano size particles of 0.17 μm, 100, and 219 nm, respectively. Amino acids like glycine, proline, and hydroxyproline were found with highest level in all the body parts of the extracted gelatin using HPLC.     

Seasonal differences in the properties of gelatins extracted from skin of silver carp (Hypophthalmichthys molitrix)

The gelatins were extracted from skins of silver carp (Hypophthalmichthys molitrix) caught in winter and summer, respectively. The physicochemical (molecular weight distribution and melting point) and rheological characteristics (viscosity property), as well as functional properties (emulsifying capacity and stability) of the gelatin from winter silver carp skin were compared with those of the summer equivalent. The results showed the properties of the summer gelatin were superior to those of the winter one, showing higher viscosity, emulsion stability, melting point and lower concentration for gelling. The summer gelatin has slightly denser strands of the gel microstructure which was observed by scanning electron microscopy (SEM). Different properties of gelatins from skin of silver carp may be attributed to the big discrepancy of the environmental temperature in the two seasons.     

Physical, mechanical, and barrier properties of carp and mammalian skin gelatin films

Films of 0.11 to 0.13 mm thickness were prepared using gelatins from the skins of cultured freshwater carp species and mammalian gelatins viz., porcine and bovine skin gelatin. A comparative study was made on the physical, mechanical, and barrier properties of these films. The amino acid composition, gel strength, clarity, and gel setting point of the gelatins were also determined. Carp skin gelatins had a lower imino acid content (19.16% to 20.86%) than mammalian skin gelatins (22.91% to 23.7%). Grass carp gelatin had gel strength of 230.2 B that is comparable to the reported value for bovine skin gelatin (227.2 B). The bloom values of rohu and common carp skin gelatins were 188.6 B and 181.3 B, respectively, which were significantly lower than mammalian gelatins. Mammalian gels have significantly higher (P < 0.05) setting temperatures (23.7 to 24.2 °C) than carp skin gelatins. Tensile strength (TS) was lowest for films from common carp and rohu skin gelatin (490 and 497 kg/cm(2), respectively) and highest for porcine skin gelatin film. The degree of transparency (L*) was significantly higher for films from grass carp, bovine hide, and pork skin gelatin films. Carp skin gelatin films had significantly lower water vapor permeability (WVP) and oxygen permeability (OP) than mammalian skin gelatin films, which indicated that carp skin gelatin based films have superior barrier properties than mammalian skin gelatin films.     

Optimization of Extraction Conditions for Pollock Skin Gelatin

ABSTRACT: Seven potential variables, pretreatment temperature, pretreatment time, concentration of OH⁻, concentration of H⁺, extraction temperature, extraction time, and skin/water ratio, were investigated by a 2^7-3 fractional factorial design to identify critical control factors for pollock skin gelatin extraction, and 3 responses, yield, gel strength, and viscosity, were evaluated. The results suggest that 4 variables, pretreatment temperature, concentration of OH⁻, concentration of H⁺, and extraction temperature, have significant effects on gelatin extraction, and these key factors were then selected for the subsequent optimization using response surface methodology with a 4-factor, 5-level central composite rotatable design. It suggests that a concentration of OH⁻ at 0.25 mol/L, a concentration of H⁺ at 0.09 mol/L, a pretreatment temperature at 2°C, and an extraction temperature at 50°C, will give the highest values for the 3 responses. The predicted responses for these extraction conditions are that the yield will be 18%, gel strength will be 460 g, and viscosity will be 6.2 c P.     

鲢鱼皮改性明胶复合多肽锌对草鱼的保鲜作用

研究鲢鱼皮谷氨酰胺转胺酶（transglutaminase,TGase）改性明胶复合多肽锌对冷藏草鱼段的保鲜效果。通过测定草鱼段在4 ℃冷藏过程中感官评分、硫代巴比妥酸（thiobarbituric acid,TBA）、挥发性盐基氮（totalvolatile basic nitrogen,TVB-N）、pH值和菌落总数等指标,评估不同处理条件下草鱼品质的变化情况。结果表明,改性明胶及其复合多肽锌对草鱼均有明显的防腐保鲜作用,有效抑制了草鱼TBA值、TVB-N值、pH值的升高以及菌落总数的增长。与海藻酸钠多肽锌处理的涂膜组草鱼相比,改性明胶单独涂膜组的保鲜效果与之相当,而改性明胶复合多肽锌膜组在贮藏前6 d的保鲜效果明显比海藻酸钠复合多肽锌组更好,一级及二级鲜度贮藏期均比海藻酸钠多肽锌复合组延长了3 d。因此,与海藻胶相比,改性鱼皮明胶是一种良好的涂膜材料,可以有效提高水产品的保质期。     

不同提取温度对白鲢鱼皮明胶理化性质的影响

本实验以白鲢鱼皮为原料提取鱼皮明胶,考察不同提取温度（30、50、70、90、100 ℃）对鱼皮明胶得率和理化性质的影响。结果表明：不同温度条件下提取的鱼皮明胶的紫外吸收峰均在波长218 nm左右;明胶提取率在提取温度为90 ℃时最大,为（86.91±0.98）%;50 ℃条件下提取的鱼皮明胶的凝胶强度最大,为（896.75±117.03）g;聚丙烯酰胺凝胶电泳图谱显示,30、50 ℃条件下提取的鱼皮明胶由α1、α2、β 3 条肽链组成,70、90、100 ℃条件下提取的鱼皮明胶由于明胶分子的热降解,电泳条带不明显;30、50、70、90、100 ℃条件下提取的鱼皮明胶的热变性温度分别为（97.88±2.65）、（108.66±0.43）、（106.48±3.33）、（100.27±2.37）、（99.56±0.37）℃;提取温度越高,明胶的G’’和G’值越小、流变性能越差。     

Extraction and functional properties of gelatin from the skin of cuttlefish (Sepia officinalis) using smooth hound crude acid protease-aided process

The characteristics and functional properties of gelatin from skin cuttlefish (Sepia officinalis) were investigated and compared to those of halal bovine gelatin (HBG). The gelatin extraction efficiency was improved by an acid-swelling process in the presence of smooth hound crude acid protease extract (SHCAP). The yields of gelatins from cuttlefish skin after 48 h with acid and with crude acid protease (15 units/g alkaline-treated skin) were 2.21% and 7.84%, respectively. The gelatin from skin cuttlefish had high protein (91.35%) but low fat (0.28%) contents. Compared to HBG, the cuttlefish-skin gelatin (CSG) has different amino acids composition than halal bovine gelatin. CSG contained slightly low hydroxyproline and proline (180‰) than HBG (219‰), whereas the content of serine was higher (49‰ versus 29‰). The gel strength of the gelatin gel from CSG (181 g) was lower than that of HBG (259 g) (p < 0.05) possibly due to lower hydroxyproline content. Cuttlefish-skin gelatin exhibited a similar emulsifying activity but greater emulsifying and foam stability than the halal bovine gelatin (p < 0.05). Foam formation ability, foam stability and water-holding capacity of CSG were slightly lower than those of the HBG, but fat-binding capacity was higher in the cuttlefish gelatin.     

Gelatin hydrolysates from sliver carp (Hypophthalmichthys molitrix) improve the antioxidant and cryoprotective properties of unwashed frozen fish mince

In this study, gelatin extracted from silver carp skin was hydrolysed by different enzymes (alcalase, papain and flavourzyme), aiming to improve the storage stability of unwashed fish mince during freeze-thaw cycles. Flavourzyme hydrolysates exhibited the highest DPPH• scavenging activity (1.2-fold of alcalase, 1.6-fold of papain) and reducing ability (1.2-fold of alcalase, 2.3-fold of papain), while the alcalase hydrolysates demonstrated the highest Fe²⁺ chelating ability. Moreover, fish mince treated with the mixture of flavourzyme hydrolysates and sucrose exhibited higher sulfhydryl and salt-soluble protein contents, greater Ca²⁺-ATPase activity and better water holding capacity. Hence, the gelatin hydrolysates of flavourzyme from silver carp skin are promising candidates as natural and high-performance antioxidant and cryoprotectants in fish mince processing.     

安康鱼皮明胶的制备及性质研究

以安康鱼皮为原料,采用碱法(浸灰法)提取鱼皮明胶,通过正交试验法对安康鱼皮明胶的提取工艺进行优化,并分别对明胶黏度、色价、等电点、氨基酸组成进行了测定。结果表明,优选出鱼皮明胶最佳提取工艺为Ca(OH)2质量分数0.2%、料液比为1∶10、提取温度为10℃、浸灰时间7d,明胶的提取率为11.23%。     

广西本地鲢鱼和长丰鲢肌肉营养成分分析与品质评价

为比较分析广西本地鲢和长丰鲢肌肉品质差异,选取这两个鲢鱼群体中体质量相近的雌雄个体各5尾,测定这4组鱼肉的营养成分、系水力、酸度以及质构特性等相关指标,并进行肌肉营养评价。结果显示:4组鱼肉中粗蛋白含量丰富(17.34%~18.57%),本地鲢雌雄鱼肌肉粗脂肪、粗灰分显著高于长丰鲢,但硬度、弹性和咀嚼性均显著低于长丰鲢雄鱼(P<0.05)。本地鲢雄鱼的回复性显著高于其余3组鱼肉,但粘性显著低于长丰鲢雌鱼(P<0.05),两种鲢鱼雌雄个体间的大部分质构指标差异不明显。4组鱼肉检测出的17种氨基酸中,Asp含量最高,其次为Glu和Lys,His和Cys的含量最低,EAA/TAA和EAA/NEAA的比值分别在39.61%~41.11%和65.60%~69.80%之间,与WHO/FAO要求的40%和60%的理想蛋白质比值接近;氨基酸指数(EAAI)均高于85分(86.13~100.00)。本地鲢雄鱼的∑TAA、∑EAA、∑FAA及EAAI均为最高。4组鱼肉检测出的脂肪酸种类均多于20种,且∑UFA和∑PUFA分别占脂肪酸总量在80%和40%以上。除长丰鲢雄鱼外,其余3组鱼肉的DHA含量均为最高,分别为30.40%、40.36%和24.01%。本地鲢的∑PUFA以及EPA+DHA含量均高于长丰鲢,而∑SFA略低于长丰鲢。结论:两种鲢鱼肌肉营养含量和组成比例均能较好地满足人体需求,本地鲢肌肉较长丰鲢更嫩,多不饱和脂肪酸含量更高。     

Properties of Alaska Pollock Skin Gelatin: A Comparison with Tilapia and Pork Skin Gelatins

ABSTRACT:  The objective of this work was to compare the physiochemical and rheological properties of Alaska pollock skin gelatin (AG) to those obtained for tilapia and pork skin gelatins. Results were also obtained for some mixed gels containing AG and pork skin gelatin, or AG and tilapia gelatin. AG contained about 7% hydroxyproline (Hyp), which was lower than that of tilapia (∼11%) or pork skin gelatin (∼13%). Most of the protein fractions in AG were α chain, β chain, and other oligomers. The gel strength of AG was 98 gram-force at 10 °C, and increased at a greater rate than other gelatins with decreasing temperature. The gel melting point of AG was the lowest with the oil-drop method, while the viscosity of AG was the highest of the samples studied. The rheological properties of gelatins were determined using small amplitude oscillatory shear testing. G' was nearly independent of frequency for most of the gelatin gels, but AG gels showed a slight dependence on G' and a minimum in G". G' was found to be a power law function of concentration for all gelatins used: G'= k × Cⁿ. In rheological measurements, AG also showed the lowest gel melting temperature and sharpest melting region. Increasing gelatin concentration resulted in a higher melting temperature and a broader melting region for all gelatin gels. For both the AG-pork and AG-tilapia mixed gels, the gel melting temperatures decreased and melting regions narrowed as the AG fraction was increased.     

大鲵肌肉与皮中胶原蛋白比较研究

针对大鲵肉中肌基质蛋白和大鲵皮提取的胶原蛋白基础特性进行比较研究。采用酸法、胃蛋白酶法提取大鲵肌基质蛋白和大鲵皮中的胶原蛋白,测定胶原蛋白的分子质量、光谱特性、羟脯氨酸含量、微观结构与黏度。结果表明：大鲵皮、大鲵肉中肌基质蛋白的酸溶性胶原蛋白提取率分别达18.29%和7.08%,酶提胶原蛋白提取率分别为25.67%和18.65%;酸提大鲵皮、大鲵肌基质蛋白中胶原蛋白羟脯氨酸含量分别为（16.05±0.16）%和（10.49±0.42）%,酶提分别为（18.04±0.08）%和（8.67±0.12）%;酸提与酶提胶原蛋白紫外光谱及红外光谱特性基本相似,酸提大鲵皮胶原蛋白的种类比肌基质蛋白中提取的胶原蛋白种类更多,酶提大鲵皮中胶原蛋白电泳条带比肌基质蛋白中提取的胶原蛋白条带更为清晰,但分子质量基本一致;扫描电子显微镜观察结果表明,酸提的2种来源胶原蛋白网状结构较酶提更为完整;2 种来源的胶原蛋白黏度存在显著差异（P＜0.05）。大鲵肉中肌基质蛋白与大鲵皮胶原蛋白特性相同,可作为补充胶原蛋白制品及化妆品原料进行开发。     

Rheological properties of gelatin from silver carp skin compared to commercially available gelatins from different sources

Gelatin is used as a functional ingredient in many foods, pharmaceuticals, and cosmetics as a stabilizing, thickening, and gelling agent. The rheological properties of gelatins are important in the potential functionality of gelatin. This study is designed to determine the rheological properties of gelatin extracted from the skins of silver carp (Hypophthalmichthys molitrix Valenciennes 1844). The extracted gelatin is compared with commercially available gelatins from different sources. The results indicate that the stress-strain relationship of gelatin gels remained in the linear region over a broad range of strains and stresses and gave similar elastic moduli at varying frequency, stress, and strain levels. One exception was a commercial high molecular weight fish skin gelatin that gave a lower elastic modulus indicating that its gel strength was low compared to the other gelatin samples studied. Gel strength varied between 220 and 1230 g while viscosity varied between 4.53 and 6.91 cP among the samples. Melting and gelling temperatures varied between 14.2 and 32.3 °C and 3.2 and 25.4 °C, respectively. Texture profile analysis was done at 2 deformation levels, 25% and 75%, and the results correlated well with gel strength. The correlations between hardness, cohesiveness, and gumminess and gel strength were 0.98, 0.82, and 0.99, respectively, at 25% deformation but lower at 75% deformation. The results suggest that rheological measurements might be used to quickly estimate gel strength using less material. In addition, the silver carp skin gelatin seemed to be of equal quality to some of the commercial gelatins.     

硬骨鱼纲鮟鱇鱼与其他鱼皮基本成分对比及分析

对鮟鱇鱼鱼皮、金鳟鱼鱼皮和大马哈鱼鱼皮的基本成分、氨基酸含量、脂肪酸含量及矿物质含量进行比较和分析。3种鱼皮的粗蛋白质含量是大马哈鱼鱼皮(31.1%)>金鳟鱼鱼皮(30.41%)>鮟鱇鱼鱼皮(20.46%),氨基酸组成相似,3种鱼皮中氨基酸含量最高的均为甘氨酸,分别为26.83,180.00和71.78 mg/g,3种鱼皮的EAAI值均为1.29,均可作为开发蛋白质类产品的优质蛋白源;3种鱼皮饱和脂肪酸占脂肪酸总量比例分别为23.03%,33.37%和26.18%,占比最大的是金鳟鱼鱼皮,单不饱和脂肪酸占比最大的是大马哈鱼鱼皮,多不饱和脂肪酸占比最大的是鮟鱇鱼鱼皮;鮟鱇鱼鱼皮和金鳟鱼鱼皮含有丰富的矿物质元素,含量最丰富的均为钙,含量分别为1537.15和9199.03 mg/kg;大马哈鱼皮中的矿物质元素较少。鮟鱇鱼鱼皮与其他2种鱼皮氨基酸组成相似,脂肪酸相差较大,矿物质元素较其他2种更丰富。     

草鱼鱼鳞明胶的提胶工艺及特性研究

探讨草鱼鱼鳞明胶的提胶条件及其特性。采用正交试验研究pH值、温度和时间对鱼鳞明胶品质的影响,利用物性仪、高效液相色谱仪和红外光谱仪等对制备的明胶特性进行分析研究。得到最佳提胶条件:提胶液pH值为6、提胶温度为55℃和时间为6h。得到的明胶提取率为35.56%,黏度为6.04mPa·s,凝胶强度为478.58g,等电点为pH值7.6,亚氨基酸(脯氨酸和羟脯氨酸)含量达21.6%。所得鱼鳞明胶结构稳定,为较高品质的明胶。     

Chemical composition and characteristics of skin gelatin from grey triggerfish (Balistes capriscus)

Gelatin was extracted from the skin of grey triggerfish (Balistes capriscus) by the acid extraction process with a yield of 5.67 g/100 g skin sample on the basis of wet weight. The chemical composition and functional properties of gelatin were investigated. The gelatin had high protein (89.94 g/100 g) but low fat (0.28 g/100 g) contents. Differences in the amino acid composition between grey triggerfish skin gelatin (GSG) and halal bovine gelatin (HBG) were observed. GSG contained a lower number of imino acids (hydroxyproline and proline) (176 residues per 1000 residues) than HBG (219 residues per 1000 residues), whereas the content of serine was higher (40 versus 29 residues per 1000 residues, respectively). The gel strength of the GSG (168.3 g) was lower than that of HBG (259 g) (p < 0.05) possibly due to lower hydroxyproline content. Grey triggerfish skin gelatin exhibited a slightly lower emulsifying activity and water-holding capacity but greater emulsifying and foam stability, foam formation ability and fat-binding capacity than the halal bovine gelatin (p < 0.05). SDS-PAGE of GSG showed high band intensity for the major protein components, especially, α- and β-components and a similar molecular weight distribution to that of standard calf skin collagen type I.     

Yield,viscosity, and gel strength of wami tilapia (Oreochromis urolepis hornorum) skin gelatin: Optimization of the extraction process

A factorial design and response surface methodology were used to optimize the extraction process of tilapia skin gelatin (Oreochromis urolepis hornorum). The concentrations of NaOH (0.15%–0.35%) and H₂SO₄ (0.15%–0.35%), the extraction temperature (40°C–60°C), and the extraction time (3–15 h) were independent variables. Response variables were yield (%), viscosity (mPa·s), and gel strength (g). The NaOH (%) and H₂SO₄ (%) concentrations had significant influences (p<0.05) on viscosity and gel strength, while the extraction temperature (°C) and the extraction time (h) showed significant influences (p<0.05) on all dependent variables. Increasing the temperature and extraction time provided higher yields with a reduction in the gelatin viscosity and gel strength. Tilapia fish skin can be used as a source for production of gelatin.     

不同加热条件对复合鱼糜凝胶特性的影响

本研究考察了鲢鱼鱼糜和带鱼鱼糜形成的复合鱼糜的破断力和凹陷深度在不同凝胶化条件下的变化规律。实验中各处理组的蛋白含量均为12%,其中蛋白比例为100%鲢鱼鱼糜,100%带鱼鱼糜,以及鲢鱼鱼糜和带鱼鱼糜的蛋白含量比例为9:1,8:2,7:3和6:4。结果表明:在凝胶化温度为30℃时,复合鱼糜的破断力均高于鲢鱼鱼糜,在鲢鱼鱼糜和带鱼鱼糜比例为7:3时破断力和凹陷深度均达到最大值,此时也高于带鱼鱼糜;而在凝胶化温度为40℃时,带鱼鱼糜添加量为40%时,破断力和凹陷深度达到最大,此时的凝胶特性优于带鱼鱼糜。带鱼鱼糜和鲢鱼鱼糜在50℃时均出现凝胶劣化现象。当带鱼鱼糜添加量为10%时,复合鱼糜对鲢鱼鱼糜和带鱼鱼糜的凝胶劣化均有显著的抑制作用。