牛宰后肌肉生物电阻抗值、pH值、失水率的变化及相互关系的研究

对牛宰后骨骼肌肉的生物电阻抗值、pH值、失水率进行测试,结果表明:宰后10 d牛肉样3项指标均有明显的变化,且做出了相应的变化曲线图;电阻抗与pH值、电阻抗与失水率、pH值与失水率之间均呈现相关性,相关系数在α=0.05水平下显著.     

牛宰后肌肉生物电阻抗值、pH值、失水率的变化及相互关系的研究

本实验对牛宰后骨骼肌肉的生物电阻抗值、pH值、失水率进行了测试,且作出了相应得变化曲线图.结果表明宰后10d牛肉样三项指标均有明显的变化.电阻抗与pH值、电阻抗与失水率、pH值与失水率之问均呈现相关性,相关性在α=0.05水平下显著.     

正向近冰点温度下肉牛骨骼肌主要生化指标变化特性的研究

本文对30头肉牛宰后经电刺激的胴体从背最长肌肉处取样在近冰点温度(1～-1℃)下贮存10d过程中游离Ca2+、ATP、总游离氨基酸、糖原、失水率的变化进行了研究。结果表明,10d中糖原、总游离氨基酸、ATP、失水率的变化几乎是同步的,均在刚宰后的0～1d(24h)中变化明显,第2d(48h)是转折点,而游离Ca2+第3d(72h)是转折点。作出了相应的变化曲线图,对指标间作Pearson相关性分析表明:游离钙与可溶性磷、游离钙与失水率、可溶性磷与失水率、糖原与总游离氨基酸、糖原与可溶性磷之间相关系数均极显著(p<0.01);游离钙与糖原之间相关系数显著(p<0.05);并且得出了相应的相关方程。对牛肉样的五项指标进行综合分析可知:所测定的牛肉样品在宰后约13.5h就进入了僵直起始阶段,而到宰后接近48h僵直达到了最大化。     

猪宰后不同部位白肌肉与正常肉品质变化、能量代谢的差异

对猪宰后不同部位白肌(pale soft exudative,PSE)肉与正常肉的品质变化及能量物质的代谢差异进行研究。选取"杜长大"阉公猪宰后背最长肌、股二头肌均为正常肉和PSE肉,测定不同时间点肉品质指标(pH值、离心失水率、剪切力、L*)及能量物质(糖原、腺苷三磷酸(adenosine triphosphate,ATP)、腺苷二磷酸、腺苷酸)含量的变化,并分析各自的相关性。结果表明:宰后2 h内,股二头肌ATP含量显著高于背最长肌(P0.05)。宰后8 h内所有样本ATP含量下降显著(P0.05);宰后48 h内,正常肉股二头肌糖原含量显著高于其他样本(P0.05);离心失水率变化和L*值变化呈正相关(P0.01);糖原含量和ATP含量的变化呈正相关(P0.01)。因此,股二头肌肉品质优于背最长肌,股二头肌的糖原、ATP含量高于背最长肌,背最长肌能量代谢速率高于股二头肌。     

牛宰后肌肉生物电阻抗值与失水率的变化及相互关系的研究

本试验对牛宰后骨骼肌肉的生物电阻抗值、失水率进行了测试,结果表明宰后十天牛肉样二项指标均有明显的变化,且做出了相应的变化曲线图。电阻抗与失水率之间呈现相关性,相关系数r=0.12698,在a=0.05水平下显著。     

牛宰后肌肉生物员阻抗值与失水率的变化及相互关系的研究

本试验对牛宰后骨骼肌肉的生物电阻抗值、失水率进行了测试,结果表明宰后十天牛肉样二项指标均有明显的变化,且做出了相应的变化曲线图.电阻抗与失水率之间呈现相关性,相关系数r=0.12698,在a=0.05水平下显著.     

面条制作中面絮特性与面团流变学特性的关系研究

本试验选用13种小麦样品,将面絮进行粒度分级,探究面絮粒度与面团流变学特性和面条品质的关系。结果表明:粒径d0.336 mm的面絮含量与糊化温度呈显著负相关(r=-0.60,P0.05);0.336~0.75 mm的面絮含量与吸水率、弱化度、糊化温度分别呈显著正相关(r=0.64,P0.05)、显著负相关(r=-0.65,P0.05)和显著负相关(r=-0.60,P0.05);0.75~1.5 mm的面絮含量与弱化度呈极显著负相关(r=-0.74,P0.01);1.5~2 mm的面絮含量与吸水率、弱化度分别呈极显著负相关(r=-0.72,P0.01)和显著正相关(r=0.63,P0.05);2~3 mm的面絮含量分别与吸水率、弱化度呈显著负相关(r=-0.63,P0.05)和极显著正相关(r=0.78,P0.01);3~4 mm的面絮含量与弱化度、糊化温度分别呈极显著正相关(r=0.69,P0.01)和显著正相关(r=0.59,P0.05);d4 mm的含量与糊化温度呈显著正相关(r=0.67,P0.05)。最后得出粒径d1.5 mm的面絮含量多有利于提高面条品质,而d1.5 mm的含量多不利于提高面条品质。     

负向近冰点温度下绵羊宰后肌肉主要理化指标变化

以宰后未经速冷处理的绵羊左后大腿为对照组,以宰后经过6h速冷处理的绵羊左后大腿为处理组,在-1～1℃贮存,并对其3～216h内肌肉中糖原、巯基、pH、失水率、游离钙离子浓度、游离氨基酸、游离羟脯氨酸的变化进行了研究。结果表明,在宰后3～216h内处理组的糖原含量、pH、失水率始终显著(P<0.05)高于对照组;处理组巯基含量始终稍低于对照组,游离羟脯氨酸含量处理组稍低于对照组,但差异不显著;游离钙离子浓度、游离氨基酸含量宰后3～48h先下降随后逐渐升高到最大值后转为下降的(p<0.05)变化规律基本一致。并且得出了部分相应的相关方程。利用主成分分析及METLAB软件对肉样的七项指标进行分析可知,在3～216h内糖原含量、pH、失水率、巯基含量、游离氨基酸含量等对肌肉僵直化进程起着重要的作用。所测定的肉样在宰后9h就进入了僵直起始阶段,在宰后48h僵直结束。     

宰后成熟时间对不同年龄牦牛肉用品质的影响

研究宰后成熟时间对不同年龄牦牛肉用品质（pH值、肉色、肌红蛋白含量、剪切力、失水率、蒸煮损失率）的影响,并分析成熟时间、年龄与肉用品质之间的相关性。结果表明：宰后成熟过程中,不同年龄牦牛肉L*值和b*值随着成熟时间的延长先上升后下降,而a*值先下降后上升;肌红蛋白含量随着成熟时间的延长而降低;pH值在成熟的前3 d发生了显著的变化（P＜0.05）,成熟过程中不同年龄牦牛肉pH值没有显著差异（P＞0.05）;失水率和蒸煮损失率在宰后成熟的第3天时达到最大;成熟3 d后,剪切力值显著降低（P＜0.05）;年龄与牦牛肉用品质指标均呈正相关,而成熟时间与L*值、b*值、失水率、蒸煮损失率呈较强的正相关,与剪切力、肌红蛋白含量呈显著负相关（P＜0.05）;牦牛宰后经过7 d的成熟,可以降低因屠宰年龄不同而产生的差异,同时也可以改善肉的嫩度。     

鲜活虹鳟鱼的呼吸频率与肌肉品质的相关性

为探讨鲜活虹鳟鱼的呼吸频率与肌肉品质之间的相关性，研究了不同呼吸频率所对应的肌肉品质的变化。测定了乳酸、糖原、丙二醛（Malondialdehyde,MDA）以及核苷酸类化合物含量和加压失水率。结果表明，随着呼吸频率的上升，糖原含量下降、丙二醛和核苷酸类化合物含量、加压失水率上升。当呼吸频率从83升至95次/min，乳酸含量由初始值1.46 mmol/g prot显著上升至2.37 mmol/g prot(P<0.01)。皮尔逊相关分析显示鲜活虹鳟鱼的呼吸频率与乳酸含量、MDA值、加压失水率呈现出极显著相关性（P<0.01），与糖原含量、AMP含量、IMP含量以及Hx和HxR总含量等肌肉品质呈现出显著相关性（P<0.05），相关系数分别为0.987、0.951、0.939、-0.897、0.847、0.896、0.882。这表明呼吸频率与肌肉品质具有强相关性，说明通过监测虹鳟鱼的呼吸频率变化可以对鲜活虹鳟鱼的肌肉品质进行初步预测。     

Isolation,Composition, Structure,Properties, Modifications,and Uses of Yam Starch

Starch is the major carbohydrate in yam tubers and can amount up to 80% of the dry matter. The starch quality determines the quality of food and industrial products made from yam tubers. This review summarizes the present knowledge of the isolation, composition, structure, property, modifications, and uses of starches from diverse yam species. Compared with other tuber and root starches, there is a lack of systematic information on the yam starches. This hinders the further development of yams as sustainable crops as well as the value‐added processing of the starches. Therefore, suggestions on how to better understand and utilize these starches are provided.     

Mineral contents of some southern Italian wines. II. Determination of Li, Na, Mg, K, Ca, Co, As, Rb, Sr, Ag, Sb, Ba

Following our study of the mineral contents of some Southern Italian wines, this work reports on the detection of 12 elemental components. The elements were determined using ICP-AES, flame atomic emission or absorption spectroscopy. The values determined for Li, Na, Mg, K, Ca, Rb, Sr and Ba were within the usual ranges for wines (average values for these elements were: 0.010, 26.2; 94.4; 888; 94.0; 3.30, 0.82 and 0.11 mg/l respectively). All the wines contained low levels of As, the concentrations of which were always under 0.20 mg/l, the maximum level permitted by E.E.C. standards. The measuring of Co, Ag, and Sb led us to ascertain, in all the wines, concentrations lower than 0.01 mg/l for Co and Ag and below the instrumental detection level for Sb (0.06 mg/l). In a previous study wines from D.O.C. areas of Southern Italy were analysed by the technique of inductively coupled plasma atomic emission spectroscopy (ICP-AES), for 14 minerals. This paper deals with further investigation of the mineral composition of the same wines for different metal constituents, analysed by ICP-AES, flame atomic emission, or atomic-absorption spectroscopy (two techniques). The first technique was applied to the detection of Co, As, Sr, Ag, Sb, and Ba. The alkaline metals Li, Na, K, and Rb were determined by flame atomic emission, a technique which possesses better detection limits for these elements. For Mg and Ca the atomic absorption methods were applied.     

卷烟中锂、铬、镍、铜、砷、硒、钼、镉、铊和铅含量分析

采用微波消解-电感耦合等离子体质谱法测定了41个牌号烤烟型卷烟和雪茄烟样品烟丝中的锂、铬、镍、铜、砷、硒、钼、镉、铊和铅含量,并按照类型和价位对卷烟中这10种有害元素含量进行了统计分析。结果发现:①卷烟中锂和铜的含量较高,铊的含量很低,铬、镍、镉、铅、砷、硒和钼7种元素的平均含量为0.55～4.42μg/g;②雪茄烟中铬、镍、砷、钼、镉、铊和铅的含量一般高于烤烟型卷烟,而硒元素的含量则相反,但差别较小;烤烟型卷烟中锂和铜的含量与雪茄烟没有显著差异;③高档卷烟中的锂、镍、镉、铊和铬含量较低,而砷、铅的含量较高;不同价位卷烟的铜、硒和钼含量差异不显著。     

Survey of trace elements (Al,As, Cd,Cr, Co,Hg, Mn,Ni, Pb,Se, and Si) in retail samples of flavoured and bottled waters

Concentrations of eleven trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) were measured in 39 (natural and flavoured) water samples. Determinations were performed using graphite furnace electrothermetry for almost all elements (Al, As, Cd, Cr, Co, Mn, Ni, Pb, and Si). For Se determination hydride generation was used, and cold vapour generation for Hg. These techniques were coupled to atomic absorption spectrophotometry. The trace element content of still or sparkling natural waters changed from brand to brand. Significant differences between natural still and natural sparkling waters (p < 0.001) were only apparent for Mn. The Mann–Whitney U-test was used to search for significant differences between flavoured and natural waters. The concentration of each element was compared with the presence of flavours, preservatives, acidifying agents, fruit juice and/or sweeteners, according to the labelled composition. It was shown that flavoured waters generally increase the trace element content. The addition of preservatives and acidifying regulators had a significant influence on Mn, Co, As and Si contents (p < 0.05). Fruit juice can also be correlated to the increase of Co and As. Sweeteners did not provide any significant difference in Mn, Co, Se and Si content.     

Varied Composition of Tocochromanols in Different Types of Bran: Rye,Wheat, Oat,Spelt, Buckwheat,Corn, and Rice

The profiles of tocopherol (T) and tocotrienol (T3) homologues in 37 samples of seven different types of bran (rye, wheat, oat, spelt, buckwheat, rice, and corn), available on the Polish market, were studied. Tocochromanols were identified and quantified by reverse phase-high-performance liquid chromatograph/fluorescence detector and reverse phase-ultra performance liquid chromatography-electrospray ionization/mass spectrometry. Only rice bran contained all eight tocochromanol types. Corn bran lacked β-T3; rye, wheat, oat, and spelt bran lacked γ-T3 and δ-T3; and buckwheat bran lacked β-T3, γ-T3, and δ-T3. In buckwheat and corn bran tocopherols predominated (98 and 78%, respectively); whereas rye, wheat, oat, spelt, and rice bran were rich in tocotrienols (78, 76, 66, 87, and 66%, respectively). The average total tocochromanol contents in the oat, corn, spelt, buckwheat, wheat, rye, and rice bran were 5.5, 16.2, 15.8, 14.7, 12.8, 10.7, and 9.1 mg/100 g of dry weight, respectively. Tocochromanol concentrations in samples of the same type bran from different sources varied considerably. Better labeling of bran products to reflect this variation would assist with control of vitamin E daily dietary requirements.     

Optimization of extraction conditions of total phenolics, antioxidant activities, and anthocyanin of oregano, thyme, terebinth, and pomegranate

The purpose of this study was to evaluate the total phenolic extracts and antioxidant activity and anthocyanins of varieties of the investigated plants. These plants include oregano, thyme, terebinth, and pomegranate. The optimum extraction conditions including temperature and solvent of the extraction process itself were investigated. Total phenolic and anthocyanin extracts were examined according to Folin-Ciocalteu assay and Rabino and Mancinelli method, respectively. The effect of different extracting solvents and temperatures on extracts of phenolic compounds and anthocyanins were studied. Plant samples were evaluated for their antioxidant chemical activity by 2, 2-diphenyl-1-picrylhydrazl assay, to determine their potential as a source of natural antioxidant. Results showed that all tested plants exhibited appreciable amounts of phenolic compounds. The methanolic extract (60 °C) of sour pomegranate peel contained the highest phenolic extract (4952.4 mg/100 g of dry weight). Terebinth green seed had the lowest phenolic extract (599.4 mg/100 g of dry weight). Anthocyanins ranged between 3.5 (terebinth red seed) and 0.2 mg/100 g of dry material (thyme). Significant effect of different extracting solvents and temperatures on total phenolics and anthocyanin extracts were found. The methanol and 60 °C of extraction conditions found to be the best for extracting phenolic compounds. The distilled water and 60 °C extraction conditions found to be the best for extracting anthocyanin.     

ICP-MS测定饼干中的铅、砷、铬、镉、铜、锌、铁和锰

探讨了应用电感耦合等离子体质谱仪测定饼干中铅、砷、铬、镉、铜、锌、铁和锰8种重金属元素的方法。运用微波消解系统对样品进行消解,以铋、锗、钪和铟作为内标物,用ICP-MS对消解液进行检测,并采用国标方法对其结果进行验证。利用加标回收率试验和国家标准物质小麦(GBW 10052)检测试验考察了方法的准确性和可靠性。结果表明,该方法所测元素在标准溶液浓度范围内呈线性关系,相关系数均大于0.999,方法检出限在0.002~0.500 mg/kg之间,相对标准偏差均小于6.55%,本法与国标方法测量结果的相对偏差在3.73%~8.40%之间,加标回收率在88.0%~106%之间,标准物质的测定值与标准参考值符合要求。     

The effect of storage of canned juices on content of the metals Fe, Cu, Zn, Pb, Sn, Al, Cd, Sb and Ni

The increase in concentration of iron, copper, zinc, lead, antimony, aluminium, cadmium, tin and nickel over a 2 year's time of juices of peach (prunus persica), pear (pyrus communis), apricot (prunus vulgaris) and apple (malus pumila) was determined. The results show a considerable increase in Fe, Cu, Pb, Zn and Sn with time, while the change in Al, Cd, Ni and Sb is negligible.     

Analysis of cheese for histamine, tyramine, tryptamine, histidine, tyrosine, and tryptophane

A method is described for determining the content of selected biologically active amines (histamine, tyramine, tryptamine) and amino acids (histidine, tyrosine, tryptophane) in cheeses by high performance liquid chromatography. The amines and amino acids were quantified by employing a counter ion-containing mobile phase and by comparing peak areas of high performance liquid chromatography charts for sample cheeses versus standard cheeses containing known amounts of added amines based on dual injections of samples and standards. Recovery of amines and amino acids varied from 87.5 to 111%. Histamine, which has been associated with food poisoning in concentrations of 185 mg/100 g in Swiss cheese and 180 to 500 mg/100 g in fish, was found in concentrations above 500 mg/100 g in Swiss cheese. The high performance liquid chromatography analytical method should be useful for screening to detect cheese samples containing toxic amounts of histamine and for research studies designed to determine the cause and effect relationships for histamine production in cheese.     

接装纸中汞、砷、铅等8种元素的分析研究

本文利用电感耦合等离子体发射光谱仪(ICP-AES法)同时测定接装纸样品中铅、铜、镉、铬、锡、锑元素含量,汞、砷元素含量采用冷原子吸收光谱法和银盐法测定.结果表明接装纸样品中锡元素含量最高,铜次之,汞、砷、铅相比,砷元素含量较高,部分样品中砷、铅元素含量超出食品包装用纸的最高限量标准.采用ICP-AES法同时测定接装纸6种元素,操作简便,重复性好,回收率高.此外,本文还对接装纸荧光物质和脱色程度进行了测定分析,从随机抽检的47份国产、进口接装纸样品看,进口白色接装纸无荧光,国产白色接装纸有荧光,珠光色接装纸个别有荧光,纸边为白色的接装纸荧光程度不一.脱色试验表明,进口接装纸,国产印刷型接装纸、珠光纸不脱色,涂布型接装纸均有不同程度的脱色.