磷脂酶活性对冷却肉持水性的影响

对正常肉和PSE肉样的肉质特性和磷脂酶活性进行了测定和分析。宰后PSE肉的pH1h和pH24h低于正常肉,而L值(宰后1h、24h)、脂肪氧化程度、汁液流失率、贮藏损失、蒸煮损失和磷脂酶A2总活性明显高于正常肉。冷却肉的汁液流失率与pH1h和pH24h呈强负相关,与T1h、磷脂酶A2总活性和非钙依赖型磷脂酶A2呈显著正相关。结果说明,宰后的低pH、宰后早期肌肉高温和磷脂酶A2活性对冷却肉汁液流失有重要作用。     

HADH酶法快速区分新鲜肉与解冻肉方法的建立

为快速区分新鲜猪肉与解冻猪肉,以新鲜猪肉(冷鲜肉与鲜宰肉)和解冻猪肉为研究对象,优化并建立根据HADH酶活值快速区分新鲜猪肉和解冻猪肉的方法。研究结果显示,HADH酶活值的最佳测定时间为150 s,双乙酰辅酶A(Acetoacetyl-Co A)最适添加量为10μL,浸提液最佳反应体积为22.5μL,浸提液最佳反应时间为15 min;利用该方法测得的鲜宰三层肉、鲜宰排骨肉、鲜宰里脊肉和鲜宰前腿肉与对应部位的冷鲜肉HADH酶活值无显著性差异,不同部位新鲜肉(鲜宰肉与冷鲜肉)的HADH酶活值与对应部位解冻肉的HADH酶活值具有极显著差异;判别分析结果结合显著性分析结果显示,当样品HADH酶活值小于186时为新鲜猪肉,大于250时为解冻猪肉,介于两者之间时需重新判断,利用该阈值判断的加密样品准确率为100%。该研究为快速判断新鲜猪肉和解冻猪肉提供参考,为解冻肉鉴别的深入研究提供理论基础。     

苏尼特羊宰后成熟过程中肌原纤维蛋白特性与肉品质的变化分析

以6月龄苏尼特羊股二头肌为材料,测定其宰后成熟过程中(0～3 d)的肉品质、肌原纤维蛋白功能特性和蛋白降解相关指标,旨在探究肌原纤维蛋白对宰后肉品质的影响,并确定苏尼特羊合适的宰后成熟时间.结果表明,4项肉品质指标(pH值、色泽、剪切力和蒸煮损失率)中,pH值、蒸煮损失率和剪切力在成熟2 d时达到最优值,并与成熟3 d...     

宰后糖酵解对肉品质影响的研究进展

宰后糖酵解作用在肌肉宰后变化过程中起到至关重要的作用。糖酵解系统的各组分,如肌糖原,糖酵解酶等,以及糖酵解潜力和糖酵解速率都是影响宰后肉质量变化的主要因素,它们的变化影响极限pH值(pHu)或受极限pH值(pHu)影响,进而影响色泽、嫩度、持水性、多汁性、风味等直接反映肉品质的指标。本文针对宰后糖酵解对肉品质影响的研究进展作一综述。     

缺氧诱导因子对滩羊肉宰后初期能量水平及肉色的影响

为研究缺氧诱导因子（hypoxia-inducible factor 1，HIF-1）对滩羊肉宰后成熟48 h内糖酵解关键酶、能量水平、pH值及肉色的影响，本实验以4 ℃成熟2、6、12、24、48 h的滩羊背最长肌为研究对象，测定不同成熟期HIF-1表达量，磷酸丙糖异构酶（triose-phosphate isomerase，TPI）活力，能量物质三磷酸腺苷（adenosine triphosphate，ATP）、二磷酸腺苷（adenosine diphosphate，ADP）、单磷酸腺苷（adenosine monophosphate，AMP）水平，肌肉pH值及肉色的变化，并对HIF-1表达量与TPI活力，ATP、ADP、AMP含量，pH值及肉色进行相关性分析。结果表明，宰后2～24 h内HIF-1表达量迅速升至最高值，24 h后有所下降；TPI活力于宰后6 h升至最高，随后逐渐降低；宰后48 h内能量物质ATP、ADP、AMP水平均随成熟时间延长逐渐降低；宰后48 h内pH值显著降低（P＜0.05）；肉色指标L*、a*值及b*值均随成熟时间延长显著升高（P＜0.05）。宰后成熟2～48 h内滩羊肉HIF-1表达量与TPI活力、能量物质水平、肉色及pH值均显著相关（P＜0.05、P＜0.01），可能是由于受宰后缺氧信号诱导，HIF-1表达量于宰后6 h内迅速升高，HIF-1复合体转移至细胞核与糖酵解基因结合，促进糖酵解相关基因表达，促使糖酵解途径增强，提高了糖酵解相关酶活力，并降低肌肉pH值。综上，HIF-1可能通过调控宰后糖酵解及肌肉pH值影响肉色。     

宰后贮藏过程中羔羊肉食用品质的变化

研究宰后不同时间羔羊肉食用品质的差异。以羔羊背最长肌为研究对象,测定4℃贮藏条件下,宰后不同时间(1、6、12、24、72、120、168 h)羔羊肉中心温度、菌落总数、pH值、肌节长度、剪切力、肉色、肌红蛋白相对含量和蒸煮损失的变化。结果表明:宰后羔羊肉的pH值从宰后1 h的6.45下降到宰后120 h的5.40左右;宰后1 h和6 h羔羊肉的肌节长度无显著变化(P0.05),宰后12 h最短,宰后24 h后开始变长,而宰后120、168 h变化不显著(P0.05);羔羊肉亮度值(L*)随宰后时间的延长呈上升趋势,红度值(a*)和黄度值则先升高后降低,且氧合肌红蛋白相对含量与a*变化规律一致;羔羊肉剪切力呈现先上升后下降的趋势,在宰后12 h达到最大;宰后1 h羔羊肉的蒸煮损失最低,随后不断增加,168 h时达到最大。综上,宰后6 h前的羔羊肉处于僵直前期,宰后6～24 h时处于僵直期,宰后24～120 h处于解僵期,宰后120 h时解僵过程完成;僵直前和解僵后羔羊肉的食用品质存在差异,僵直前羔羊肉的保水性较高,成熟后羔羊肉的嫩度较高,L*和a*较高。     

不同坡度装卸台装卸牛对牛肉品质的影响

为研究不同坡度的装卸台装卸牛对牛肉品质的影响,选取西门塔尔肉牛20头,随机分为4组,各组分别通过(30,40,50°)坡度装卸台装卸牛后,然后对牛进行屠宰,分析宰后牛肉pH值、肉色、失水率、蒸煮损失率和剪切力。结果表明:随着装卸台坡度的增大,宰后牛肉pH值、牛肉L*值、a*值呈下降趋势(P0.05),牛肉b*值、剪切力、肉失水率、蒸煮损失率呈增加趋势(P0.05)。通过坡度为30°的装卸台装卸牛,宰后牛肉品质较好,在实际生产中应降低装卸台坡度,以提高牛肉品质。     

肉兔肉质评定方法的建立

为探究肉兔肉质评定方法,选取体质健康的商品肉兔30只,按解剖学和兔肉商品学原理对其胴体分割。对前腿、后腿及背最长肌分别测定pH值、剪切力、肉色、滴水损失、蒸煮损失等指标。结果表明,上述各部位其测定指标的平均值分别为:前腿pH值为6.42,剪切力为0.26kg.f,肉色L*值31.61、a*值3.94、b*值2.73,蒸煮损失为6.88%;后腿pH值为6.35,剪切力为0.18kg.f,肉色L*值25.25、a*值4.11、b*值2.53,蒸煮损失为32.88%;背最长肌pH值为5.68,剪切力为0.22kg.f,肉色L*值26.28、a*值3.71、b*值3.55,滴水损失为8.44%,蒸煮损失为6.82%。因此,对pH值的测定,选择后腿中心部位为最佳的评定部位;对剪切力的测定,选择背最长肌为最佳的评定部位;对肉色、亮度的评定中选择后腿为最佳的评定部位,红色度和黄色度的评定中选择前腿为最佳的评定部位;对滴水损失的测定,选择背最长肌前段为最佳的评定部位;对蒸煮损失的测定,选择前腿或背最长肌为最佳的评定部位。     

不同部位及地区藏羊肉的肉品质及其组织学特性

为探究藏羊肉不同部位及不同地区同一部位肌肉的品质差异,该研究以大通县、同仁县、祁连县的6月龄藏羊为研究对象,采集颈肉、肩肉、前腿、前腱、羊脊排、腰肉、胸腹肉、臀肉、臀腰肉、粗米龙、膝圆、里脊及后腱13个部位的肉样,分析不同部位的组织学特性与品质间的相关性。结果表明：不同地区及不同部位之间肉品质特性具有较大差异。肩肉的蛋白质含量高（29.05%）、脂肪含量高（9.24%）、拥有较好的色泽（L*值为39.89）,但水分含量低;前腿的肌纤维密度较小（785.50 N/mm2）、肌纤维直径最粗（52.06 μm）、水分含量较大（72.43%）;羊脊排具有较好的肉色;臀肉的pH值较小（6.18）、脂肪含量低（1.20%）;臀腰肉具有最小的剪切力值（24.10 N）和pH值（6.16）;与祁连和同仁的藏羊肉相比,大通的藏羊肉蛋白质及脂肪含量高、蒸煮损失率低,具有良好的色泽和质构特性。综合分析：臀腰肉的肉质最嫩,膝圆、臀肉及羊脊排的肉质较优。藏羊肉的蒸煮损失率平均值为29.74%,适合蒸煮。不同地区藏羊肉品质受海拔影响显著,前腿肉、臀腰肉、羊脊排和膝圆可以用来开发优质产品。     

藏鸡不同部位肌肉物理特性及加工性能的研究

以藏鸡胸部肉和大腿肉作为实验原料,采用TPA测定和感官评定,研究了藏鸡不同部位肌肉的物理特性和加工性能。研究结果表明：腿部肉pH高于胸部肉,差异不显著;胸部肉离心失水率高于腿部肉,差异显著;胸部肉含水量略高于腿部肉,差异不显著;腿部肉系水力高于胸部肉,差异显著;腿部肉蒸煮损失高于胸部肉,差异显著;质地剖面分析测定的硬度、弹性、内聚性、咀嚼性的测定值皆为腿部肉高于胸部肉,差异显著;沃-布氏剪切法测定的剪切力值及剪切强度的测定值皆为腿部肉高于胸部肉,差异显著;感官评定的多汁性及总体接受性皆为腿部肉高于胸部肉,且差异显著。与其它鸡种相比,藏鸡肉富含优质蛋白质,氨基酸总量和必需氨基酸含量较高,且物理特性和加工性能均具有显著优势。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press