中华鳖营养、风味及功能特性研究进展

中华鳖是我国传统食疗滋补佳品。本文阐述了国内外关于中华鳖营养、风味及功能特性等三方面的研究现状,指出中华鳖风味独特、营养丰富,是一种高蛋白低脂肪的食物原料,其组织富含多糖、胶原蛋白、牛磺酸、维生素B-17等功能因子。此外中华鳖在预防及治疗心脑血管疾病、抗肿瘤、增强免疫与延缓衰老等方面具有一定功效。      

中华鳖腿肉蛋白的理化性质

以中华鳖肉为原料,分析其蛋白质的氨基酸组成及蛋白组分,并利用碱溶酸沉法提取鳖肉蛋白,研究其功能与结构性质。结果表明,中华鳖肉中蛋白含量丰富(18. 61 g/100 g),且氨基酸组成比例优于FAO/WHO推荐标准;其肌红蛋白含量为2. 22 mg/g,且多以氧合肌红蛋白的形式存在;鳖肉蛋白中肌原纤维蛋白、总基质蛋白、碱溶蛋白、碱不溶蛋白、肌浆蛋白和酸溶蛋白的含量分别占总蛋白含量的48. 35%、17. 25%、11. 84%、10. 84%、10. 04%和1. 54%。鳖肉蛋白分子质量集中在29. 0～200 k Da,二级结构α-螺旋、β-折叠和β-转角的相对含量分别为59. 39%、34. 92%和5. 69%,肌球蛋白和肌动蛋白热变性温度分别在49. 5和83. 6℃,鳖肉蛋白乳化性能优于大豆分离蛋白,起泡性则反之。该研究对于深入研究和开发中华鳖肉蛋白资源具有一定的参考价值。     

中华鳖肉蛋白质营养特征分析及评价

为了合理利用中华鳖资源,测定了其腿肉及裙边一般营养成分,并对其中的蛋白质进行了组分的分离,之后通过氨基酸自动分析仪对中华鳖腿肉及其分离蛋白进行了氨基酸组成的进一步研究。实验结果表明:中华鳖腿肉及裙边蛋白质含量分别为18.20%、20.97%(占湿重),脂肪含量很低分别为0.96%、0.42%。其腿肉蛋白质组成中肌原纤维含量最高,占总蛋白质总量的39.47%,肌浆蛋白含量次之(31.79%),总基质蛋白含量最低(28.72%)。裙边蛋白质组成中,以总基质蛋白为主,占总蛋白含量的92.25%。分析中华鳖腿肉及分离蛋白的氨基酸组成,各蛋白氨基酸比例存在一定的差距。腿肉及其中的肌原纤维蛋白必需氨基酸含量符合FAO/WHO理想蛋白模式,对比其各蛋白组分发现只有腿肉氨基酸评分(AAS)均大于100,说明中华鳖腿肉营养更均衡,具有较高的营养价值。      

中华鳖蛋白质组分的分步提取及其抗氧化活性

以野生中华鳖全鳖粉为原料,采用分步提取法对中华鳖的蛋白类成分进行分离,并利用等电点沉淀、醇沉、超过滤等方法分离纯化出各蛋白质组分,并对其各组分的抗氧化性进行研究,并对抗氧化活性高的组分进行分子质量测定分析;还原力的测定以还原剂BHT 为对照,清除DPPH 自由基能力的测定则进行直线回归分析并计算 IC50 值。结果表明：糖蛋白组分及水溶性蛋白组分抗氧化活性较高,IC50 值为0.21mg/mL 和1.94mg/mL。因此,中华鳖各蛋白组分有较高的抗氧化能力且呈显著的剂量效应关系,其在抗氧化方面和保健食品方面具有巨大的开发潜力。     

Physicochemical and functional properties of fern rhizome (Pteridium aquilinum) starch

Starch isolated from fern rhizome was studied for physicochemical and functional properties. The recrystallization method was used for separation and purification of AM and AP from the starches. The fern rhizome starch contained 25.38 ± 0.40% AM. XRD studies showed that fern rhizome starch exhibited a C‐type diffraction pattern. SEM showed that granule shape was oval mostly, and the size ranged from 7 to 28 µm. The gelatinization temperature was from 58.94 ± 0.11°C to 71.73 ± 0.22°C, and the melting enthalpy was 12.86 ± 0.53 J/g. According to the viscosity measurement with Brabender viscograph, fern rhizome starch presented higher peak viscosity, which showed that it had more swelling power. Compared with corn and potato starches, fern rhizome starch had a lower transparency. The RS in the fern rhizome starch vermicelli prepared with extrusion method was around 10.49 ± 0.46%.     

Physicochemical and functional properties of makal (Xanthosoma yucatanensis) starch

Physicochemical and functional properties of makal (Xanthosoma yucatanensis) starch were determined. Granules were oval in shape and 12.4 μm average diameter. Starch purity was high (96.7%) with low protein (0.1%), fat (0.2%), fibre (0.4%) and ash (0.1%) contents. Amylose content was 22.4%. The gelatinization temperature was 78.5 °C and transition enthalpy was 15 J/g. At 90 °C, solubility was 32.9%, swelling power was 28.6 g water/g starch and water absorption capacity was 19.2 g water/g starch. Pasting characteristics were: temperature 75 °C, maximum viscosity 280 BU, breakdown −8 BU, setback 180 BU and consistency 172 BU. Clarity, expressed as transmittance, was 35.8%. Gel deformation was 20.8% with a 0.03 kgf maximum load. Makal starch’s high gelification temperature and firmness make it appropriate for use in high temperature food systems, but its low stability in refrigeration and freezing cycles make it inadequate for use in foods subject to those conditions.     

佛罗里达鳖与中华鳖不同部位营养成分的比较分析

对佛罗里达鳖(Apalone ferox)与中华鳖(Pelodiscus sinensis)的肌肉、裙边与脂肪组织的营养成分进行分析比较。结果表明:佛罗里达鳖肌肉组织中的粗蛋白与粗脂肪含量显著低于中华鳖(p0.05)。佛罗里达鳖裙边组织中的粗蛋白与粗脂肪含量显著高于中华鳖(p0.05)。佛罗里达鳖肌肉组织中的必需氨基酸(EAA)含量和药效氨基酸(PAA)含量显著低于中华鳖(p0.05)。佛罗里达鳖裙边组织中的总氨基酸(TAA)含量、鲜味氨基酸(DAA)含量、PAA含量均显著高于中华鳖(p0.05)。在肌肉组织和裙边组织中,佛罗里达鳖的氨基酸评分(AAS)、化学评分(CS)和必需氨基酸指数(EAAI)均小于中华鳖。佛罗里达鳖肌肉组织和脂肪组织中的脂肪酸种类和多不饱和脂肪酸总量少于中华鳖(p0.05)。可知,佛罗里达鳖与中华鳖的肌肉组织和裙边组织中的氨基酸组成均衡,均属优质蛋白质。佛罗里达鳖肌肉、裙边和脂肪组织的营养价值和食疗价值低于中华鳖,但其裙边组织的食用风味优于中华鳖。     

Physicochemical properties of leftover egg yolk after livetins removal

Isolation of immunoglobulin Y (IgY) from egg yolk using water-dilution method generates large quantities of leftover pellet as the co-product. Although egg yolk is well known for its great emulsion property, there is a lack of understanding on how livetins removal would affect the emulsion and rheological properties of the pellet. Therefore, the objective of this study was to determine the effect of soluble protein removal on emulsifying and rheological characteristics of the leftover egg yolk. Egg yolk pellet exhibited distinct structural and physicochemical properties after soluble protein removal. Emulsions prepared from pellet were more vulnerable to coalescence instability than that of egg yolk, although both had a similar oil droplet size. Egg yolk displayed a Newtonian behaviour, compared to a shear-thinning behaviour of pellet. Pellet showed a higher apparent viscosity as well as higher viscoelastic moduli than those of egg yolk, probably due to increased hydrogen bond and hydrophobic interactions in the pellet. Therefore, the changes on the emulsion stability and the rheological properties of egg yolk after soluble proteins removal should be considered in food formulation and processing. Further study is needed to improve the emulsion property of pellet for uses in the food industry.     

Physicochemical and techno-functional properties of acid-aided pH-shifted protein isolate from over-salted duck egg (Anas platyrhucus) albumen

Here, potential physicochemical and techno-functional properties of the albumen protein recovered from over-salted albumen by an effective acid-aided pH-shift process (POA) were tested in comparison with the fresh albumen (FA) and albumen protein recovered from fresh albumen by acid-aided pH-shift process (PFA). POA contained 66.73% protein and 11.30% sodium (dry basis). Surface hydrophobicities of PFA and POA were higher than FA (P < 0.05), whereas the reactive sulfhydryl content of FA was higher than PFA and POA (P < 0.05). PFA had the highest whiteness followed by POA and FA, respectively. Single endothermic peak in DSC thermogram was found at 86.86, 89.67 and 98.96 °C for FA, PFA and POA, respectively. Long-term salting impaired the solubility, viscosity, emulsifying activity and gelation but not for foaming of albumen protein isolate. FA can be softly gelled with continuously packed structure, whereas PFA and POA underwent agglutination to form white clot suspension with spongy network.     

芸豆蛋白的理化功能特性研究

选取4个芸豆品种,以大豆蛋白为对照,采用碱提酸沉法提取芸豆蛋白并分析其理化功能特性。结果表明:芸豆蛋白含有9种必需氨基酸,且必需氨基酸占总氨基酸的比例(57%~62%)高于大豆蛋白(47%),黑芸豆的限制性氨基酸比例(2.59%)高于其他参试品种及大豆蛋白(1.53%~1.89%)。不同品种芸豆蛋白亚基主要分布在47 ku左右,由2个或3个亚基组成,次要条带间存在一定差异,大豆蛋白的条带与芸豆蛋白条带显著不同。芸豆蛋白的溶解性和吸水性略低于大豆蛋白,乳化性及乳化稳定性、发泡性及泡沫稳定性、吸油性和最小凝胶浓度均接近或高于大豆蛋白,红芸豆和白芸豆蛋白的功能特性高于黄芸豆和黑芸豆蛋白。     

Physicochemical and functional properties of whole legume flour

The physicochemical, functional and pasting properties of whole flours from pinto bean, lima bean, red kidney bean, black bean, navy bean, small red bean, black eye bean, mung bean, lentil and chickpea were investigated. Significant differences in physicochemical characteristics and functional properties were observed (P < 0.05). Bulk densities, water absorption indices, water solubility indices, oil absorption capacities, emulsion activities, and emulsion stabilities ranged from 0.543 g/mL to 0.816 g/mL, 4.09 g/g to 6.13 g/g, 19.44 g/100 g to 29.14 g/100 g, 0.93 g/g to 1.38 g/g, 61.14%–92.20%, and 84.15%–96.90%, respectively. Phaseolus legume flour exhibited higher water absorption capacity, oil absorption capacity, emulsion activity, and emulsion stability compared with other kinds of legume flour. Pasting properties were significantly different (P < 0.05). Pasting temperatures and the peak, final, and setback viscosities of the flours ranged from 73.2 °C to 83.0 °C, 96.2 RVU to 216.8 RVU, 118.5 RVU to 243.8 RVU, and 28.3 RVU to 103.2 RVU, respectively.     

大鲵皮明胶-茶多酚复合膜液理化性质及功能性研究

以大鲵皮明胶和茶多酚为原料制备复合膜液,研究不同质量分数茶多酚的引入对复合膜液性质的影响。结果表明,引入茶多酚后造成了大鲵皮明胶复合膜液L*值和p H值下降,而a*值和b*值增加。与对照组相比,含0. 4%茶多酚复合膜液凝胶强度明显提高(P <0. 05),但是茶多酚质量分数超过0. 8%时,会造成复合膜液凝胶强度下降(P <0. 05)。剪切流变分析表明,与对照组相比,各组复合膜液表观黏度和最终剪切应力呈先增加后降低的趋势。红外光谱分析表明,引入不同质量分数茶多酚,大鲵皮明胶复合膜液酰胺A、Ⅰ、Ⅱ、Ⅲ带吸收峰发生了不同程度偏移。此外,引入茶多酚后,各组复合膜液的DPPH自由基清除能力和还原能力得到显著提升(P <0. 05)。综合考虑,含0. 4%茶多酚的明胶复合膜液具有较好的理化和功能性质,今后可进行食品复合保鲜液及可食膜性能的深入研究。     

Physicochemical and functional properties of whole and defatted meals from Mexican (Cucurbita pepo) pumpkin seeds

Chemical composition and some functional and thermal properties in whole pumpkin seed meal (WPSM) and defatted pumpkin seed meal (DPSM) were determined. The DPSM exhibited higher water absorption capacity (3 g H₂O per g sample), water solubility capacity (8.75%), oil absorption capacity (2.73 g oil per g sample), emulsifying capacity (61.71%), foaming capacity (51.92%) and gelling capacity (12% w/v) than the WPSM. The DPSM also had better swelling power (3.33% at 60 °C, rising to 4.31% at 90 °C), higher phase transition temperatures (T₀ = 80.04 °C, T_p = 86.50 °C and T_f = 93.20 °C) and a higher phase transition energy (0.93 J g^?1). However, the WPSM had higher bulk density (0.57 g cm^?3) and better foam stability (from 30 to 120 min). Micrographs showed defatting to cause microstructural changes in meal starch granules and proteins. Its high protein content makes the DPSM a potential alternative input in the food industry.     

Physicochemical,nutritional and functional properties of Cucurbita moschata

Cucurbita moschata is widely planted in most parts of the world, and is rich in carotenoids, vitamins, dietary fiber, minerals, and phenolic compounds. It also has important medicinal value. Some related research has proven that Cucurbita moschata has the potential ability to induce anti-obesity, anti-diabetic, antibacterial, and anticancer effects. At the same time, it has attracted more attention in the medical field. These nutrients and bioactive compounds in Cucurbita moschata have important effects on human health. In order to make better use of this crop, it still needs further study. Therefore, the purpose of this article is to summarize the physicochemical properties and nutritional components of Cucurbita moschata, and to provide a reference for further research on the benefits of on human health.     

Physicochemical and functional properties of protein concentrates from pulses

The physicochemical and functional properties of protein concentrates from peas, lentils, navy beans, chickpeas, and defatted chickpeas were investigated. Protein concentrates were prepared using a laboratory wet milling procedure. Chemical composition and colour of the protein concentrates were significantly different among the various pulses. Functional properties of the chickpea protein concentrates, including water hydration capacity, foaming capacity, and emulsion capacity, were improved significantly after a defatting step was added prior to the fractionation process. Navy bean protein concentrate had the largest foaming capacity, whilst chickpea protein concentrates had the smallest. Protein concentrates from lentils had the most stable foams after 120 min, whilst those from chickpeas had the least stable foams. Navy bean protein concentrate also had the highest emulsion capacity, whilst pea protein concentrates had the poorest. Protein content of the protein concentrates was positively correlated, whilst the fat content was negatively correlated with foaming capacity (r = 0.663, p < 0.001 and r = − 0.712, p < 0.001, respectively). Water hydration capacity of the protein concentrates was significantly correlated with ash content (r = 0.597, p < 0.01), fat absorption (r = 0.535, p < 0.01), foaming capacity (r = 0.775, p < 0.001) and foam stability at 120 min (r = 0.595, p < 0.01). Ash content and foaming capacity were significantly correlated with emulsion capacity (r = 0.497, p < 0.05, and r = 0.552, p < 0.01, respectively).     

Protein hydrolysates from meriga (Cirrhinus mrigala) egg and evaluation of their functional properties

Protein hydrolysates from underutilised meriga (Cirrhinus mrigala) fish egg were prepared by using commercial Alcalase and papain enzymes. The degree of hydrolysis was 62% for Alcalase and 17.1% for papain, after 90 min digestion at 50–55 and 60–65 °C, respectively. The protein content of Alcalase-produced hydrolysate was higher (85%) than that of papain hydrolysate (70%) (p < 0.05). Hydrolysis by both enzymes increased protein solubility of fish egg protein hydrolysates to above 72.4% over a wide pH range (2–12). Results showed that the hydrolysates had good fat absorption capacity (0.9 and 1.0 g/g sample), foam capacity (70% and 25%) and emulsifying capacity (4.25 and 5.98 ml/g hydrolysate), respectively for Alcalase and papain protein hydrolysates. Gel filtration chromatograms and SDS–PAGE analysis indicated the distribution of smaller peptides. These results suggested that fish egg protein hydrolysates could be useful in the food industry.     

Characterisation of volatile compounds of farmed soft‐shelled turtle (Pelodiscus sinensis) by solid‐phase microextraction and the influence of matrix pH on the release of volatiles

Although farming and consuming of soft‐shelled turtle has been practised for centuries, the aroma‐impact compounds in the meat have not been determined. Furthermore, matrix pH, usually changing during processing and storage stage, was rarely investigated for the influence on volatile profiles. To these aims, soft‐shelled turtle meat was subjected to different pH conditions and the potential volatile compounds were analysed under different extraction conditions by headspace solid‐phase microextraction (HS‐SPME). A total of forty‐three volatiles were identified; in which, nonanal, (E, E)‐2, 4‐heptadienal, octanal, decanal, hexanal, (E)‐2‐nonenal, heptanal, 1‐octen‐3‐ol and o‐xylene were assigned as aroma‐impact compounds by high relative odour activity value (ROAV). Overly basic or acidic pH significantly (P < 0.05) facilitated the release of volatiles under moderate extraction conditions. The total volatilisation increased by 30.1% to 298% in pH‐shifted samples, while the highest one was found in pH 2 or pH 11. However, the results of principal components analysis (PCA) demonstrated that increased extraction time or temperature hindered the pH enhancement.