酰化和酶法修饰后牦牛乳酪蛋白热稳定性变化

采用酰化试剂和转谷氨酰胺酶(TG)对牦牛乳中的酪蛋白进行改性,并对改性后的酪蛋白进行热稳定性研究,通过在280nm处测定吸光度值来评价酪蛋白热稳定性。结果表明,酪蛋白经TG交联后热稳定性提高。采用不同酰化试剂修饰后,牦牛乳酪蛋白热稳定性增强,不同改性修饰的酪蛋白热稳定性差异较大,琥珀酸酐修饰酪蛋白热稳定性最强。结果可为牦牛乳酪蛋白修饰和产品开发及利用提供参考依据。     

小麦面筋蛋白琥珀酰化修饰研究

采用琥珀酸酐对小麦面筋蛋白进行改性修饰，系统研究了底物浓度、改性剂用量和反应温度对反应程度、溶解性、乳化性、起泡性和泡沫稳定性等蛋白功能特性的影响。优化出小麦面筋蛋白琥珀酰化的最佳条件：琥珀酰化底物浓度10％，琥珀酸酐用量15％，反应温度45℃。应用红外光谱对最优条件下改性的面筋蛋白结构进行了表征。将琥珀酰化改性后的小麦面筋蛋白添加至小麦粉中，面团粘着性提高32％。     

酰化修饰对牦牛乳酪蛋白结构及理化性质的影响

以丁二酸酐、丁二酸、乙酸酐为酰化试剂对牦牛乳酪蛋白进行酰化修饰,研究了酪蛋白空间结构、缓冲性能、钙镁磷含量、色度的变化。结果显示,丁二酸酐、乙酸酐、丁二酸酰化程度分别为90.0%、87.9%、18.5%。酰化修饰后,牦牛乳酪蛋白二级结构以转角和β-折叠的含量为主;丁二酸酐酰化促使酪蛋白形成少量规则的α-螺旋结构,含量为9.4%,其他样品中未检出。丁二酸酐酰化使其三级结构变化程度最大,丁二酸最小。酰化修饰后,牦牛乳酪蛋白最大荧光强度降低,除了乙酸酐修饰酪蛋白之外,其他样品最大发射波长红移;丁二酸修饰酪蛋白三级结构变化较小。酰化修饰后,酪蛋白缓冲性能增强。经酰化修饰后,牦牛乳酪蛋白中的钙、镁、磷含量均降低,但其色泽均变白。研究结果可为牦牛乳酪蛋白的改性及构效关系研究提供参考依据。     

琥珀酰化改性对米糠蛋白功能性质的影响

为了改变米糠蛋白的功能性质,扩大米糠蛋白在食品工业的应用范围,利用琥珀酸酐对米糠蛋白进行酰化改性处理。通过单因素反应,确定了琥珀酸酐酰化改性米糠蛋白的最适反应条件为:米糠蛋白浓度为10%,反应温度为35℃,琥珀酸酐/蛋白质用量为15%。在最适反应条件下,分别反应40 min、80 min,制得酰化度分别为46.8%、69.2%的琥珀酰化米糠蛋白。评价了上述两种琥珀酰化米糠蛋白制品的溶解性、乳化性、起泡性等功能性质,结果表明,琥珀酰化改性对米糠蛋白的溶解性、乳化稳定性以及起泡性均有一定改善,而酰化米糠蛋白的乳化活性、泡沫稳定性随着酰化程度的提高有所下降。     

琥珀酰化度大小对改性小麦面筋蛋白性质影响的研究

本文采用琥珀酸酐对小麦面筋蛋白进行酰化改性，讨论了琥珀酰化度大小对面筋蛋白的溶解性、乳化性、乳化稳定性、起泡性和起泡稳定性影响，并对最佳改性条件下改性小麦面筋蛋白进行了在面条加工中的应用研究。结果表明：琥珀酰化度为66．1％时改性效果最好，改性面筋蛋白的溶解度、乳化及乳化稳定性、起泡及起泡稳定性分别为5．09mg／ml，56．8％，56．4％，44．8％，25％；利用最佳改性条件下的琥珀酰化面筋蛋白生产面条，面条的综合性能均比未改性的面筋蛋白品质高。     

琥珀酰化提高大豆分离蛋白乳化性的研究

为了提高大豆分离蛋白(SPI)的乳化性,采用琥珀酸酐对大豆分离蛋白进行酰化改性。系统研究了SPI质量分数、琥珀酸酐用量和反应温度对大豆分离蛋白乳化性的影响,建立以上3因素与乳化活性和乳化稳定性关系的数学模型,并利用响应面法优化出大豆分离蛋白琥珀酰化的适宜条件:SPI质量分数6.5%、反应温度49℃、琥珀酸酐添加量11.5%。该条件下制备的琥珀酰化蛋白的乳化活性和乳化稳定性与未改性的大豆分离蛋白相比较,分别提高了2.98倍和4.86倍。     

牦牛乳酪蛋白肽制备及乙酰化脱苦

采用碱性蛋白酶对牦牛乳酪蛋白进行水解,得到牦牛乳酪蛋白肽.以醋酸酐为酰化试剂,利用结构修饰的方法对牦牛乳酪蛋白肽进行脱苦研究,探讨醋酸酐添加量、pH对牦牛乳酪蛋白肽酰化度及苦味的影响.结果显示,碱性蛋白酶最佳水解条件为,温度55℃,pH7.0,酶添加量1.25％,反应3h.维持酰化反应pH7以上,产物乙酰化程度最高,醋酸酐的添加量与脱苦效果呈正比,当醋酸酐添加量为40％时,牦牛乳酪蛋白肽酰化产物的苦味基本消失.     

琥珀酰化改性对米渣分离蛋白乳化性的影响

研究对米渣分离蛋白进行琥珀酰化改性以提高其功能特性,拓展其在食品中的应用范围。在单因素试验的基础上,通过响应面法优化琥珀酰化米渣分离蛋白的改性条件,得到乳化性较好的产物。结果表明:琥珀酸酐添加量、反应温度、pH对酰化反应均有显著影响。琥珀酰化改性的最佳条件为反应温度36.24℃,反应pH 8.57及琥珀酸酐添加量5.39%,在此条件下,琥珀酰化米渣分离蛋白的乳化性为5 551 m2/g,为未酰化米渣分离蛋白乳化性的2.64倍。采用响应面法优化琥珀酰化米渣分离蛋白乳化性的工艺条件可靠,具有实用价值。     

超声-琥珀酰化复合改性提高大豆分离蛋白乳化性的研究

为提高大豆分离蛋白的乳化性,采用超声和琥珀酰化两种方法对大豆分离蛋白进行复合改性。通过单因素实验研究底物浓度、超声功率、超声时间、琥珀酸酐添加量和酰化反应温度对大豆分离蛋白乳化性的影响。在单因素实验的基础上,运用响应面法优化出超声-琥珀酰化改性大豆分离蛋白的适宜条件:超声功率569.36W、超声时间9.79min、酰化温度49.72℃。该条件下制得的改性大豆分离蛋白的乳化活性和乳化稳定性与未改性的大豆分离蛋白相比较,分别提高了3.05倍和4.65倍。     

酰化对大豆分离蛋白乳化性能的影响

目的:研究化学改性对大豆分离蛋白(SPI)乳化性能的影响;方法:采用乙酸酐和琥珀酸酐对SPI进行化学改性;结果:随酰化试剂用量的增大,酰化程度不断提高,在相同酰化试剂用量的条件下,乙酰化程度高于琥珀酰化.SPI的乳化活性指数(EAI)和乳化稳定性(ES)都随酰化程度的增大而增大.在中性和弱碱性(pH 5.0～9.0)范围内,酰化明显提高了SPI的EAI和ES.琥珀酰化的改性效果优于乙酰化;不过离子强度削弱了SPI的EAI和Es;结论:酰化可有效提高SPI的乳化性能,其中琥珀酰化的改性效果优于乙酰化.     

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.     

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     

INFOPRINT 2014 was Successfully Held in Dongguan

Sponsored by Printing and Printing Equipment Industries Association of China （PEIAC） and organized by Print China magazine, the Seventeenth Beijing International Printing Information Conference （INFOPRINT 2014） was successfully held on 11th Dec. 2014 at Dongguan Exhibition International Hotel.