Application of pork fat diacylglycerols in meat emulsions

The properties of fat are of major importance when meat products are produced. By enzymatic modification triacylglycerols (TAGs) can be converted to diacylglycerols (DAGs) resulting in changes of the physical and chemical properties of the fat. In this study the texture as well as the hydration and binding properties were investigated in meat emulsions prepared with lard substituted with different amounts of DAGs derived from the lard. In emulsions prepared with DAGs the percentage of total expressible fluid decreased from 28.2% in products prepared with lard to 11.8% in emulsions prepared with 100% DAGs. The fat separation decreased from 10.9% to 7.8% when 10% of DAGs were applied and no fat separation was observed for emulsions prepared with 50% and 100% DAGs. Emulsions containing DAGs were more elastic and solid reflected in a significant increase in Young's modulus and the maximum hardness. The results suggest future opportunities for the application of DAGs to improve the quality of meat products.     

Comparison of crystallization properties of a palm stearin/canola oil blend and lard in bulk and emulsified form

Physical properties of lard and a palm stearin/canola oil (PSCO) blend were characterized with respect to their nucleation and crystallization properties in both bulk and emulsified form over a range of temperatures. Emulsification resulted in a significant decrease (P<0.05) in solid fat content (SFC) in both systems. A decrease in droplet size and increase in the monodispersity of the lard emulsion resulted in a significant decrease (P<0.05) in SFC. Within each fat system there was no detectable modification of the polymorphic form due to emulsification although the onset times of both phase and polymorphic transitions were delayed by emulsification. The free energies of nucleation (ΔG_3D) and diffusion (ΔG_diff) were established for lard and PSCO in order to compare the nucleation behaviour of the bulk fats.     

The effects of enzymatic interesterification on the physical-chemical properties of blends of lard and soybean oil

The main goal of the present research effort was to evaluate the physical-chemical properties of blends of lard and soybean oil following enzymatic interesterification catalyzed by an immobilized lipase from Thermomyces lanuginosa (Lipozyme™ TL IM). Lipase-catalyzed interesterification produced new triacylglycerols that changed the physical-chemical properties of the fat blends under study. Solid fat content (31.3 vs 31.5 g/100 g), consistency (104.7 vs 167.6 kPa), crystallized area (0.6 vs 11.8) and softening point (31.8 vs 32.2 °C) of lard increased after interesterification, and this was mostly due to the increase of SSS (saturated) + SSU (disaturated-monounsaturated) triacylglycerols. These contents (SSU + SSS) increased in lard after interesterification from 42.9 to 46.7 g/100 g. The interesterified blends exhibited lower values for the physical properties when compared with their counterparts before enzymatic interesterification. The interesterification of blends of lard with soybean oil increased the amounts of UUU (triunsaturated) and SSS triacylglycerols and reduced the amounts of UUS (diunsaturated-monosaturated) triacylglycerols. The interesterified blends of lard and soybean oil demonstrated physical properties and chemical composition similar to human milk fat and they could be used for the production of a human milk fat substitute.     

Effect of cooling rate on the structure and mechanical properties of milk fat and lard

The mechanical and thermal properties of a fat crystal network are determined by factors such as chemical composition, solid fat content (SFC), and crystal habit (polymorphism and microstructure). Processing conditions affect the crystallization of fats, thus having an effect on their functional properties. The effects of cooling rate on the macroscopic properties of a fat crystal network were studied by crystallizing anhydrous milk fat (AMF) and lard either rapidly (5 °C/min, Newtonian cooling) or slowly (0.1 °C/min, stepwise cooling). AMF crystallized rapidly was harder than AMF crystallized slowly and had a higher SFC. Moreover, its solid state was in a more metastable polymorphic form. Upon slow crystallization, AMF had a lower SFC and its solid state was in a more stable polymorphic form. AMF crystallized under fast cooling yielded a higher Avrami constant (k), and a lower Avrami exponent (n) than AMF crystallized under slow cooling. The microstructure was also different between the two treatments. When crystallized rapidly, crystallites were numerous and small, while a smaller number of larger crystallites were observed when crystallized slowly. Similar results were observed for lard crystallized under the same conditions. The mechanical properties of both AMF and lard, expressed as hardness, depend on a variety of factors, which include the SFC, polymorphism of the solid state as well as the microstructure of the fat crystal network.     

一种新型的减肥食用油--二甘油酯及其生理功能

主要介绍了由天然脂肪酸与甘油合成得到一种合80％二甘油酯(DAG)的减肥食用油及其生理功能。该油中的DAG有70％为1，3—DAG，经消化后成1(或3)—单甘油酯，这种产物在小肠的黏液中难以重新合成三甘油酯(TAG)。且能增加肝脏内β—氧化酶的活性和氧的利用，从而长期摄入DAG油能防止肥胖症、高血脂、脂肪肝和糖尿病的产生。     

小红栲抗性淀粉的理化功能特性

以小红栲原淀粉(NS)为对照,研究了两种小红栲抗性淀粉(RS)的体外消化特性、结构特性、糊特性和益生特性。结果显示:与原淀粉对比,小红栲湿热处理抗性淀粉(HMT RS)与酸解—湿热处理抗性淀粉(AH-HMT RS)的RS含量显著增加,属于低血糖指数(pGI)食品配料。HMT RS与AH-HMT RS的晶体结构以B-型晶体占优且平均聚合度都降低,前者的微观结构呈规则片层结构,而后者的则呈小片层散乱堆积结构。HMT RS和AHHMT RS糊的峰值黏度、谷值黏度、冷却黏度、崩解值与回值均显著降低,特别是AH-HMT RS糊的峰值黏度、谷值黏度与冷却黏度均降至14mPa·s以下,两者都只能形成低强度凝胶。HMT RS和AH-HMT RS的起始糊化温度、峰值糊化温度、终止糊化温度和糊化温度范围都显著增加,糊化焓则显著减少。以HMT RS或AHHMT RS作为唯一碳源时,后者比前者对双歧杆菌、乳酸杆菌的增殖作用更强,丁酸产生也更多。     

受精蛋孵化期间理化性质及水溶性蛋白(肽)抗氧化活性

选用三黄鸡受精蛋为原料,研究其在孵化期间水分、灰分、粗脂肪、蛋白质、多肽含量以及pH和水溶性蛋白(肽)抗氧化活性的变化。结果表明:水分、脂肪、蛋清pH在孵化期间呈下降趋势,而灰分、蛋白质、多肽和蛋黄中的pH呈上升趋势。蛋清中的水溶性蛋白(肽)具有较强的抗氧化活性,其对DPPH·和·OH清除能力和总抗氧化能力随着孵化时间的延长而增强,并且与样品浓度成正相关。15d样品(5mg/mL)清除DPPH·的能力最强,清除率为90.68%;12d和15d样品(10mg/mL)清除·OH的能力最强,清除率分别为70.09%和70.31%;6d的总抗氧化能力随样品浓度增大而增强的速率最快,浓度为5mg/mL时,695nm下的吸光值为1.53,总抗氧化能力极显著高于其他各样品(p<0.01),然而,当样品浓度同为10mg/mL时,第3、6、9、12、15d样品的总抗氧化能力无显著差异(p>0.05),但显著高于0d的样品(p<0.05)。这可为开发新型天然安全抗氧化剂的研究提供参考。      

Triacylglycerols Determination by High-temperature Gas Chromatography in the Analysis of Vegetable Oils and Foods: A Review of the Past 10 Years

The analysis of triacylglycerols by high-temperature gas chromatography, along the last 10 years has been reviewed in this paper. The interest in this topic has grown along the last years due to the triacylglycerols are the main components of oils and fats and they are being used for the characterization and authentication of foods products.

The most commonly used procedures, including the official methodologies, applying high-temperature gas chromatographic techniques are shown. Their importance in the characterization of different kind of samples, vegetable oils, seeds, dairy products, etc., is considered.

This review is not intended to be a comprehensive dissertation on the field of triacylglycerols analysis since that would require sufficient space to occupy a book in its own right. Rather, it will outline selected considerations and developments, where the technique has been applied.     

谷朊粉对大豆分离蛋白膜理化性质的影响

为利用枧水处理的谷朊粉(wheat gluten,WG)改良大豆分离蛋白(soy protein isolate,SPI)膜性质,考察了0:10、1:9、2:8、3:7和4:6的WG/SPI比例对复合膜理化性质的影响,测定膜的微观结构、蛋白结构、机械性能等理化性质。扫描电子显微镜结果显示添加的WG主要聚集在复合膜下表面,当WG/SPI比例超过2:8时膜的下表面网络结构会遭到破坏。根据傅里叶变换红外光谱和十二烷基硫酸钠-聚丙烯酰氨凝胶电泳的结果,发现WG会阻碍SPI分子之间的交联。SPI膜的抗拉伸强度和断裂伸长率分别为6.60 MPa和54.91%,伴随WG的添加抗拉伸强度逐渐下降而断裂伸长率逐渐上升。复合膜的水蒸气阻隔能力和上表面接触角随着WG比例的增加而增大。当WG/SPI比例增加到2:8时,WG/SPI复合膜的b*值达到了18.72的高值。差示扫描量热法的结果表明,在WG/SPI比例为1:9时,复合膜的热稳定性最高。本研究结果表明适当添加枧水预处理的WG能提高SPI膜的部分物理性质,这将为SPI膜理化性质改良提供新的途径。     

生物可降解聚（3-羟基丁酸-co-3-羟基戊酸共聚酯）/聚乳酸共混物的相容性和结晶性

针对聚（3-羟基丁酸-co-3-羟基戊酸共聚酯）（PHBV）热稳定性差、易分解的问题,通过与聚乳酸（PLA）采用熔融共混的方法制备了不同混合比例的的PHBV/PLA共混物,借助差示扫描量热仪、热重分析仪、动态热机械分析仪和X射线衍射仪研究了PHBV/PLA共混物的相容性、热学性能和结晶性等,并用热台偏光显微镜观察了PHBV/PLA共混物的动态热结晶过程。结果表明：PHBV/PLA共混物呈现分离的熔融温度和玻璃化转变温度,X射线衍射曲线上没有出现新的衍射峰,说明PHBV和PLA的相容性较差;PLA的加入提高了PHBV的热稳定性能,拓宽了PHBV的熔融加工窗口;随着共混物中PLA比例的增加,共混物的结晶相由“海-岛”相逐渐变成两聚合物分别连续成相。     

Effect of various dietary fats and proteins on serum cholesterol level in rats

A 60 day experiment on growing rats was performed to evaluate the effect of two protein sources (casein and soybean protein isolate) and four fats (olive oil, OO; evening primrose oil, EO; linseed oil, LO; and butter, B) on plasma lipoprotein fractions: total cholesterol (TC), high‐density lipoprotein cholesterol (HDL‐C), low‐density lipoprotein cholesterol (LDL‐C) and triacylglycerol (TAG) levels. The different protein and fat sources had no influence on body weight gain of rats. Fats had no significant effect on TC and LDL‐C. Significant differences were found only in HDL‐C. OO gave the lowest (43.3 mg dl^?1) and EO the highest (54.4 mg dl^?1) value. Proteins had a significant influence on all lipids analysed. Soybean protein caused higher TC (78.5 vs 67.9 mg dl^?1), HDL‐C and TAG levels but significantly lowered LDL‐C in the plasma of rats. These results suggest that protein has a stronger effect on cholesterol level than fat. © 2002 Society of Chemical Industry     

梯型熔解温度等温扩增检测食品中植物源成分的内标方法构建

目的 为梯型熔解温度核酸等温扩增(ladder-type melting temperature isothermal amplification, LMTIA)检测食品中植物源特异性基因建立内标方法, 同时可作为检测肉制品中植物成分的LMTIA方法。方法 针对植物ITS的共有序列, 设计LMTIA引物, 优化反应温度, 测定灵敏度, 并评估淀粉制品、蜂蜜、食用油DNA提取方法与LMTIA检测方法的适应性, 以H2O、鸭肉、鸡肉、羊肉、猪肉和牛肉基因组为阴性对照测试LMTIA方法的假阳性。结果 所建LMTIA方法在最优温度57 ℃时, 灵敏度为10 pg/μuL 玉米基因组与10 pg/μL玉米基因组, 可检出肉制品掺入0.1%的玉米淀粉, 并且所选淀粉制品、蜂蜜、食用油DNA提取方法均适用于LMTIA检测, 并且所有阴性对照样品在测试中均未出现假阳性。结论 本研究建立了LMTIA检测食品中植物源特异性基因的内标方法, 排除了DNA提取引起的LMTIA检测的假阴性, 同时为肉制品中植物成分定性检测建立了LMTIA方法。     

陈窖豆豉粑黄豆原料理化特征及浸泡蒸煮特性的表征关联

源于东北和贵州两地10个不同黄豆品种的理化特征、浸泡蒸煮特性以及Pearson相关分析结果表明,贵州黄豆区别于东北大豆的高蛋白和小粒特征是其作为陈窖豆豉粑首选原料的两大优势,以物性仪测试的应力-应变（时间）曲线最大峰值（g）尤宜作为浸泡黄豆蒸煮硬度的量化表征,化学组成中蛋白含量是影响黄豆浸泡吸水率和蒸煮硬度的关键因素.     

Physicochemical properties of starch isolated from Antiaris africana seeds in comparison with maize starch

Antiaris africana seeds yielded 29.6% starch which showed appreciable high contents of ash, protein, and fat. The average diameter of A. africana starch granules was 3.98 µm compared to 8.93 µm for maize starch. A. africana starch had a C‐type XRD pattern and crystallinity of 41.5%. A. africana starch had higher AM content (24.1%) than maize starch (20.9%). The gelatinization onset temperature of A. africana starch (66.7°C) was higher than maize starch (63.1°C), but its gelatinization temperature range (8.57°C) and enthalpy (13.97 J/g) were lower than the values for maize starch (14.02°C, 14.65 J/g). The pasting temperature (P_t) and setback (V_s) were lower and breakdown (V_b) higher for A. africana starch (P_t = 82.5°C, V_s = 173.8 RVU, and V_b = 121.42 RVU) than for maize starch (P_t = 84.9°C, V_s = 183.73 RVU, and V_b = 78.58 RVU). The GPC analysis gave M_w of 2.18 × 10⁷ g/mol and radius of gyration of 95.1 nm for Antiaris starch. Antiaris starch paste exhibited poor freeze‐thaw stability but its small granule size indicates potential for application as dusting starch.     

Physicochemical Data Mining of Msalais,a Traditional Local Wine in Southern Xinjiang of China

Twelve physicochemical parameters of 15 traditional wine samples of Msalai were completely analyzed with data mining methods to understand the interaction between physicochemical attributes and the homogeneity among the Msalais samples. Although the physicochemical differences were significant among the Msalais samples, there was also significant correlation between chromaticity and turbidity, between total soluble solids and dry extract, between total phenol and chromaticity, volatile acid content, dry extract, as well as iron content. With multivariable dimension scale analysis, 12 physicochemical parameters were clustered according to their contribution to color (iron, color), flavor (volatile acids, alcohol content, total acid, phenol, total sugar), and body (dry extract, turbidity, total soluble solids, density) of Msalais. Homogeneity was observed in the physicochemical parameters of the samples from one modern factory; however, there was strong heterogeneous in the physicochemical parameters of the samples from different traditional workhouses. Data mining with the help of a variety of analytical methods provides a good foundation for the quality control of Msalais, especially for its grade estimation.     

壳/芯结构PU基纳米纤维复合纱的制备与性能研究

采用聚氨酯(PU)和镍(Ni)为原料制备纳米纤维复合纱壳层,以PU纤维丝为复合纱芯层,制备壳/芯结构PU基纳米纤维复合纱.利用金相显微镜及电子扫描显微镜观察纳米纤维复合纱的表观形貌,测试了其力学性能(断裂强力、断裂伸长率)及导电性能.研究结果表明:当纺丝液中Ni的质量浓度为0.18 g/mL时,试样的直径较大,断裂强力...     

不同牵伸倍率下聚酯复合纤维的微观结构与性能

为研究聚对苯二甲酸乙二醇酯/聚对苯二甲酸丙二醇酯(PET/PTT)并列型复合纤维制备工艺与其结构及性能之间的关系,借助二维广角X射线衍射仪、差示扫描量热仪等对未牵伸以及2.35～3.35倍牵伸纤维的结晶取向性能、热性能、力学性能以及卷曲性能进行测试与分析。结果表明：随着牵伸倍率的增加,PET/PTT复合纤维内部单组分结晶度变化有所差异,PET组分结晶度由43.04%增至45.73%,但PTT组分的结晶度几乎不变,其取向度由82.3%增大至89.2%,然后保持稳定,说明牵伸诱导取向达到饱和;同时,取向度的增大也导致PET/PTT复合纤维的弹性模量由16.8 cN/dtex增加到23.1 cN/dtex,断裂强度由2.9 cN/dtex增加到3.5 cN/dtex,但断裂伸长率由52.6%下降到38.6%;牵伸倍率的增加导致双组分纤维结构差异明显,使复合纤维的卷曲性能更加优异。     

Preparation and characterization of a temperature-sensitive nonwoven poly (propylene) with antibacterial properties

In this study, a temperature-sensitive fabric with antibacterial properties was prepared by the formation of silver nanoparticles (AgNPs) on nonwoven poly (propylene) (PP) grafted with poly (N-iso-propylacrylamide) (PNIPAAm-PP). First, PNIPAAm was grafted onto corona-treated nonwoven PP. Afterwards, silver nanoparticles were synthesized on the temperature-sensitive hydrogel layer grafted to the surface of nonwoven PP by the reduction of silver ions (Ag⁺). Fourier transform infra-red spectroscopy confirmed the presence of PNIPAAm on the nonwoven PP. scanning electron microscopy-energy dispersive X-ray spectroscopy was used to investigate surface morphology and the presence of silver particles in the samples. Inductively coupled-plasma atomic emission spectroscopy revealed that the Ag content in Ag-functionalized PNIPAAm-PP was significantly higher than Ag-functionalized corona-treated PP with the same concentration of silver solution. Moreover, the results of the swelling rate experiment confirmed that PNIPAAm-PP maintained temperature-sensitive properties after functionalizing with Ag. The results showed that the formation of AgNPs with enhancement in antibacterial property was possible onto PNIPAAm-PP.