咸蛋渗透传质与品质的研究

影响鸭蛋腌制成熟的一些因素进行正交试验,并从渗透传质的角度对其进行分析,得出影响咸蛋成熟的因素中,磷酸影响较大(在盐的浓度一定时),其次是香辛料,试验证明,香辛料对改善鸭蛋的风味有重要作用。     

咸鸭蛋清的综合利用研究进展

咸蛋清富含蛋白质,可作为香干加工的原料,但其形成凝胶的能力较弱,如不经改良、直接加热成型制作香干,产品硬度低、品质较差。本文在研究咸蛋清凝胶性能的基础上,通过配方和工艺优化,改善了产品的凝胶质构和品质,建立了免卤制、直接加热成型的咸蛋清香干加工工艺,同时对优化条件下所加工产品的质构特性、感官品质、含水量、持水率及微观结构等进行了全面的表征。结果表明,加热成型温度和时间对香干的外观形态、硬度、弹性和内聚力影响显著,80 ℃下加热2.5 h效果较好;添加新鲜全蛋液和蛋清粉能显著提升咸蛋清香干的凝胶性能和质构;适量的黄豆粉、咸蛋黄和卤汁能显著改善香干的风味和口感;通过混料设计试验优化后的香干配方如下：咸蛋清61.49%、新鲜全蛋液30.75%、蛋清粉5.00%、黄豆粉2.00%、咸蛋黄0.76%、卤汁添加量2.0%。优化条件下加工的香干感官评分高达96.80,持水率达到了90.84%,硬度、弹性和内聚力分别为2711.30 g、0.85和0.68,质地较为致密、细腻,色泽光亮。综上所述,本文通过配方优化显著改善了咸蛋清的凝胶性能,据此所建立的咸蛋清香干加工工艺可行,所加工的产品品质优良。     

咸鸭蛋蛋清对罗非鱼鱼糜凝胶品质的影响

通过检测鱼糜凝胶的质构和感官特性,探讨了咸鸭蛋蛋清对罗非鱼鱼糜凝胶品质的影响。结果表明,在鱼糜制品中添加咸鸭蛋蛋清一方面能有效改善产品的色泽,另一方面却会稍微降低鱼糜凝胶的凝胶强度和保水性,但对罗非鱼鱼糜凝胶品质无明显劣化影响。咸鸭蛋蛋白质量占混合物总蛋白质量比达到2/15时,鱼糜凝胶特性仍可满意,同时产品的风味无明显变化。     

鸭蛋腌制前后于低频波段的阻抗特性研究

盐分、出油率和硬化率是反映咸蛋品质的主要指标,通过研究鸭蛋腌制过程中蛋清和蛋黄在低频区域100Hz～12MHz的阻抗特性与理化指标的相关性来提供一套可行的检测方法。分析了腌制前后蛋清和蛋黄的主要蛋白质种类并建立了等效电路,对其阻抗特性曲线Bode图、复导纳图、实部虚部图进行拟合,确定了蛋清和蛋黄腌制前后特征频率的变化以及各自可能的散射类型;发现在102Hz频率下鸭蛋腌制过程中的盐分含量、出油率和硬化率变化与阻抗幅值有较显著的回归特性。      

咸蛋清蛋白深度酶解工艺优化研究

以咸蛋清为原料,用酸性蛋白酶对其进行酶解,以蛋白回收率和水解度为指标,通过单因素实验考察了酶解时间、加酶量、pH和酶解温度对咸蛋清深度酶解的影响,优化了咸蛋清蛋白深度酶解工艺,并对最佳工艺条件下获得的咸蛋清蛋白酶解液进行肽分子量分布的测定。研究结果表明:咸蛋清蛋白深度酶解最佳工艺条件是:稀释后的咸蛋清调节pH至4.0,酸性蛋白酶的加酶量为0.3%(E/S),温度为55℃,酶解时间为48h;此最佳工艺得到的咸蛋清蛋白酶解液中肽分子量主要为3000u以下,其中分子量为1000~3000u占49.28%,分子量为1000u以下占35.73%。      

紫外辐照法提高咸蛋清起泡性的工艺研究

咸蛋清是蛋制品的副产物,一直以来仅有少部分用于饲料,大部分被丢弃,造成了较大的环境污染和资源浪费。本实验以经超滤脱盐的咸蛋清为原料,利用紫外辐照法,研究了辐照时间、pH、温度对咸蛋清起泡力的影响。利用响应面分析法确定了最佳工艺参数为辐照时间32min,pH5.0,温度30℃。此时的咸蛋清粉的起泡力为65.33%。      

咸蛋清脱盐工艺响应面法优化

采用截留分子量为10 000的PS膜对咸蛋清进行超滤脱盐,利用响应面法进行优化分析,得出咸蛋清脱盐最佳工艺条件:超滤时间31 min,pH 7.7,稀释倍数12,压强0.48MPa,该条件下的脱盐率为62.63%,蛋白质损失率为5.3%。     

组合加工单元对盐水鸭品质的影响

采用组合加工单元的方式,以剪切力、含水量、系水力、食盐含量、脂肪含量为评价指标,研究其对盐水鸭品质的影响;并结合主成分分析法,考量组合加工单元与盐水鸭品质的关系。结果表明:组合加工单元的不同导致盐水鸭的剪切力、含水量、系水力、食盐含量、脂肪含量发生变化。原始评价指标可划分为2个主成分,累计贡献率约为95%。第一主成分由剪切力、含水量、食盐含量、脂肪含量构成,表征盐水鸭的鲜嫩、清脂的特点;系水力对第二主成分起决定作用,表征经腌制和熟制处理后的鸭肉热致凝胶状态。构建的综合评价模型表明:组合加工单元对盐水鸭品质的影响可通过主成分分析法判定,加工单元对盐水鸭的品质影响排序为:煮制>烘制>干腌>复卤。     

Impact of salted duck egg albumen powder on proteolysis and gelling properties of sardine surimi

The influences of salted duck egg albumen powder (SDEAP) as salt replacer at various levels (0.5–2.5%) on autolysis and gelling properties of sardine surimi were investigated. SDEAP had high salt (33.67%) and protein contents (64.52%) with trypsin inhibitory activity of 5,975 kunits/g solid. SDEAP was white in color with L*‐value of 96.72. It had low moisture content (3.98%) and water activity (0.38). Autolysis of sardine surimi was drastically inhibited when SDEAP was incorporated with increasing levels as indicated by the more retained myosin heavy chain and the reduced trichloroacetic acid‐soluble peptide content. Breaking force and deformation of surimi gel increased, while expressible moisture content decreased as the levels of SDEAP added were increased (p < .05). Gumminess, hardness, chewiness, springiness, and cohesiveness of surimi gels also increased as SDEAP levels increased (p < .05). Lightness and whiteness were higher in all surimi gels incorporated with SDEAP than the control (p < .05). For microstructure, surimi gels incorporated with SDEAP at all levels used had finer gel network with smaller voids and more connectivity than the control gel. Thus, SDEAP could be used as a salt replacer for sardine surimi gel preparation and it could improve the properties of resulting gel.     

Protein Hydrolysate of Salted Duck Egg White as a Substitute of Phosphate and Its Effect on Quality of Pacific White Shrimp (Litopenaeus Vannamei)

ABSTRACT:  Protein hydrolysate from salted egg white (PHSEW) with different degrees of hydrolysis (DH) (3%, 6%, and 9%) was produced using pepsin. Disappearance of proteins with molecular weight (MW) of 108 and 85 kDa with the concomitant formation of proteins with MW of 23, 20, 13, and 5 kDa was observed in PHSEW. The use of PHSEW for quality improvement of Pacific white shrimp ( Litopenaeus vannamei ) was investigated. Shrimp soaked in 4% NaCl containing 7% PHSEW and 2.5% mixed phosphates (0.625% sodium acid pyrophosphate [SAPP] and 1.875% tetrasodium pyrophosphate [TSPP]) had the highest cooking yield with the lowest cooking loss ( P  < 0.05), compared with shrimps with other treatments. Nevertheless, no difference in weight gain was obtained in comparison with those treated with 4% NaCl containing 3.5% mixed phosphate ( P  > 0.05). Cooked shrimp treated with 4% NaCl containing 7% PHSEW and 2.5% mixed phosphate or those treated with 4% NaCl containing 3.5% mixed phosphate had the higher score of appearance, texture, and overall likeness but less shear force, in comparison with the control (no treatment) ( P  < 0.05). Microstructure study revealed that muscle fibers of cooked shrimp from both treatments had the swollen fibrils and gaps, while the control had the swollen compact structure. Therefore, use of PHSEW could reduce phosphate residue in shrimps without an adverse effect on sensory properties.     

鸭蛋清蛋白多肽体外抗氧化活性的研究

对经"蛋清水解专用蛋白酶-碱性蛋白酶"和"碱性蛋白酶-胰蛋白酶"双酶分步酶解鸭蛋清蛋白得到的多肽的抗氧化活性进行了研究。结果表明,当"蛋清水解专用蛋白酶-碱性蛋白酶"酶解蛋清蛋白的水解度为21%时,多肽的抗氧化活性最高,其对二苯代苦味酰基自由基(DPPH·)、羟基自由基(·OH)、超氧阴离子(O2-·)的清除率和对大豆卵磷脂过氧化作用的抑制率分别为75.76%、84.17%、72.73%和47.59%;当"碱性蛋白酶-胰蛋白酶"酶解蛋清蛋白的水解度为15%时,多肽的抗氧化活性最高,其对DPPH·、·OH、O2-·的清除率和对大豆卵磷脂过氧化作用的抑制率分别为75.15%、93.84%、58%和40.51%。产物肽的分子量均分布在小于5300D的范围内。     

脱盐咸鸭蛋清肽-亚铁螯合物的制备及表征

本文以脱盐咸鸭蛋清肽为原料,Fe Cl₂·4H₂O为铁源,以亚铁的螯合率和螯合物的得率为跟踪指标,对鸭蛋清肽-亚铁螯合物的制备条件进行优化;并采用红外光谱、动态光散射仪、荧光光谱、圆二色谱手段,对肽-亚铁螯合物进行了结构表征。单因素及正交实验结果表明,鸭蛋清肽-亚铁螯合物的最佳螯合反应条件:抗坏血酸（VC）与亚铁盐的质量比为0.2∶1,鸭蛋清肽溶液的浓度为4%,肽与亚铁盐的质量比为3∶1,p H 5.5,反应温度为40℃,反应时间为40 min,乙醇的添加量为反应液体积的7倍,在此条件下亚铁的螯合率为65.15%,螯合物得率为44.46%。红外光谱显示Fe²⁺与肽的氨基端与羧基端相结合;荧光光谱表明随着Fe²⁺的增加,荧光吸收带从3822 nm显著下降为3124.44 nm（p<0.05）;激光粒度仪显示肽与肽-亚铁螯合物的半径分别为（144.23±5.86）nm和（453.66±8.74）nm;圆二色谱显示肽中α螺旋、β折叠的含量为28.66%±1.54%、10.02%±1.04%,而肽-亚铁螯合物中α螺旋、β折叠的含量为16.10%±1.96%、27.33%±1.08%,两者均发生显著变化（p<0.05）。从结构层面证实了肽-亚铁螯合物的形成。      

腌制对鸭蛋中油脂品质的影响

以新鲜鸭蛋为原料,采用裹蛋腌制法制备咸鸭蛋。研究了腌制过程中不同腌制时间对咸鸭蛋的蛋黄指数、水分含量,以及对蛋黄油皂化值、酸值、胆固醇含量、脂肪酸构成等指标的影响。研究结果表明,随着腌制时间的延长,鸭蛋中的水分含量逐渐降低,而蛋黄指数、蛋黄油皂化值、酸值、胆固醇含量逐渐增加。腌制后的鸭蛋中不饱和脂肪酸含量略有降低,而饱和脂肪酸和反式脂肪酸含量略有增加。总体而言,腌制并没有鸭蛋中蛋黄油的食用品质产生严重的影响。     

Effect of NaCl on thermal aggregation of egg white proteins from duck egg

Thermal aggregation of duck egg white solution (1 mg protein/ml, pH 7) was monitored in the presence of different NaCl concentrations (0–6%, w/w) across the temperature range of 20–90 °C. Duck egg white solution exhibited higher turbidity with coincidental increases in surface hydrophobicity and decreases in sulfhydryl group content as temperatures increased from 70 to 90 °C (p < 0.05). As NaCl concentration increased, the negative charge decreased, with coincidental increases in particle size of aggregate after heating to 90 °C. As visualised by confocal laser scanning microscopy, larger clusters of protein aggregates were observed with increasing NaCl concentrations. Major duck egg white protein with molecular mass of 45 kDa disappeared in the presence of 2–6% NaCl after heating above 80 °C, regardless of concentrations. Therefore, NaCl, especially at high concentrations, could induce thermal aggregation of duck egg white protein, which could determine the characteristics of salted egg white after heating.     

Identification of preserved egg white protein glycation and insight into the bioactivity

Preserved eggs have been reported to possess anti-inflammatory and antioxidant bioactivities, which are enhanced after protein glycation. However, it is still unknown which proteins are glycated during pickling process of preserved eggs and whether the glycated proteins are related to the bioactivity of preserved eggs. In this study, UPLC-ESI-MS/MS was used to identify glycation of proteins in preserved egg white (PEW) and duck egg white (DEW). Altogether, 142 sites on 53 glycated proteins were detected in PEW while 9 sites on 2 glycated proteins were found in DEW. Bioinformatic analysis suggested that the glycation of PEW proteins (e.g. Ovalbumin, Ovotransferrin, Albumin) were supposed to be connected with allergenicity reduction, and the enhancement of antibacterial and antioxidant bioactivities. These findings provide some indications for the future studies on the detailed bioactivities of glycated proteins in PEW, and pave the way for applied research on glycation and the development of functional foods.     

Effects of salting processes and time on the chemical composition, textural properties, and microstructure of cooked duck egg

Chemical composition, textural properties, and microstructure of cooked duck egg salted by 2 methods (coating and immersing) were determined during 4 wk of salting. As the salting time increased, moisture content increased and salt content decreased for both cooked salted egg white and yolk. Oil exudation of cooked yolk and expressible water content of cooked egg white obtained from both salting methods increased as salting proceeded (P < 0.05). After cooking, oil exudation accompanied by the solubilized pigments, especially at the outer layer of yolk, was obtained. At week 3 of salting, egg yolk from coating method had the higher egg exudation than that from immersing method. As the salting times increased, the lower hardness, springiness, gumminess, chewiness, and resilience with higher adhesiveness and cohesiveness were generally found in cooked salted egg white (P < 0.05), irrespective of salting methods. Conversely, the hardness of cooked yolk increased continuously and reached the maximum at week 2 and 2 to 3 for immersing and coating method (P < 0.05), respectively. Confocal laser scanning micrographs revealed the smaller yolk granules with more release of free lipid in salted egg after heating, compared with the fresh counterpart. As visualized by scanning electron microscope, gel of cooked salted egg white was coagulum type with larger voids. Salting methods determined oil exudation in egg yolk and texture profile of egg white gel after cooking; however, those attributes were also governed by the salting time. PRACTICAL APPLICATION: Salted duck egg can be made by 2 methods (coating and immersing) affecting the characteristic of salted egg white and yolk after cooking. Desirable cooked salted egg having the red yolk with hardness and high oil exudation could be obtained when salting was carried out for 3 and 4 wk for immersing and coating method, respectively.     

Contribution of starch and non-starch parameters to the eating quality of japanese white salted noodles

Viscograph paste viscosity parameters of starches isolated from 42 wheat varieties were highly correlated with each other and with measures of the quality of the derived Japanese white salted noodles. Better correlations with noodle quality were obtained when measurements of wheat protein and grain hardness (PSI) as well as a starch viscosity parameter were included in the regression equations.