Evaluation of cleaning procedures for allergen control in a food industry environment

The hygiene of chicken processing surfaces and retention of the wheat protein gliadin and of protein in general on those surfaces were compared in 15 trials after 3 increasingly rigorous cleaning steps. Eleven different chicken products with wheat derivatives as a batter were prepared on 3 processing lines in 15 production runs selected at random over 6 mo (5 runs were thus replicates). Using surface swabs, surface hygiene was monitored by adenosine triphosphate (ATP) bioluminescence, gliadin by immunoassay, and protein by the Coomassie dye method. Gliadin was monitored in 14 trials, protein in 5, and all trials were monitored by ATP bioluminescence. In a typical trial, gliadin values normalized to uncleaned values fell from 100000 arbitrary units, to 6000 after rinsing, to 30 (foam, rinse), to not detected (sanitize, rinse). Parallel ATP bioluminescence values also decreased, but crucially, the relative gliadin value was less than the relative ATP value after foam and rinse in all 14 trials, a result unchanged after sanitize and rinse. In trials comparing ATP and protein, the relative ATP values exceeded the relative protein values in 4 of 5 trials after foaming and after sanitizing. Thus, for these 11 products, ATP bioluminescence was a surrogate indicator of residual gliadin and probably of residual protein. Absolute gliadin concentration on an uncleaned processing line was also the basis of modeling the risk of cross-contamination of gliadin in follow-up product, where the line was hypothetically left uncleaned between production runs. The results show that all follow-up product could be declared "gluten-free" under proposed legislation, and suggest that some industrial cross-contamination risks are currently overestimated.     

橙皮提取液合成载银石墨烯研究

以新鲜澳橙果皮提取液作为还原剂和稳定剂合成载银石墨烯(rGO-Ag)。通过试验探究反应时间、温度、AgNO3浓度对rGO-Ag反应率、平均粒径大小及分散液稳定性的影响;以rGO-Ag平均粒径为考察指标进行正交试验,得到最优合成条件。结果表明,延长反应时间、提高反应温度、适当增加AgNO_3浓度可提高rGO-Ag反应率、降低平均粒径,但对分散液稳定性影响较小。正交试验结果表明,各因素对rGO-Ag平均粒径的影响大小顺序为:反应温度反应时间AgNO_3浓度,最佳工艺条件为:反应时间4h,温度100℃,AgNO_3浓度25mmol/L。透射电镜、拉曼光谱和傅里叶变换红外光谱的结果证实平均粒径为21nm AgNPs成功负载到了还原氧化石墨烯片层上。     

不同热处理方法消除焊接残余应力的研究

采用小孔法测定了不同热处理方法消除焊接残余应力的效果.结果表明:对含钼钢材来说,回火热处理仅可消除 67%的残余应力,正火加回火的热处理方法消除焊接残余应力可达94%.但过高的热处理温度有可能降低钢材的强度和韧性,热处理时一定要控制好温度和时间.     

清洗方式对空心菜采后保鲜效果的影响

以空心菜为对象,研究不同清洗方式(次氯酸钠溶液,有效氯浓度为100 mg/L;臭氧水,活性氧浓度1. 8 mg/L;超声波清洗,40 Hz、0. 33 W/cm~2)对空心菜采后贮藏保鲜效果的影响。结果表明,这3种清洗处理有利于保持空心菜的感官品质,维持较低的菌落总数水平,延缓叶绿素、Vc等含量下降,其中臭氧水清洗保鲜效果最好,相对于对照组货架期有效地延长了3 d。     

清洗方法对鲜切山药贮藏效果的影响

采用不同浓度的次氯酸钠、双氧水和柠檬酸对鲜切山药进行处理,通过测定鲜切山药储藏期间的菌落总数、丙二醛含量、失重率以及感官品质来衡量清洗效果。结果表明:次氯酸钠处理可以明显降低鲜切山药的菌落总数,但浓度过高会破坏山药的内部组织,不利于其储藏;0.6%的次氯酸钠溶液处理效果较佳,双氧水次之,柠檬酸最差。     

不同清洗方法对草莓中农药残留清洗效果的研究

目的考察不同清洗方法对草莓中农药残留的清洗效果,确定减少草莓中农药残留的最优清洗方法。方法采用正交设计的方法,用最少的实验次数,考察清洗溶剂、清洗方式、清洗时间、清洗温度等因素对清洗效果的影响,每个因素下设有不同的影响水平,充分考虑各个因素下不同水平对清洗结果的影响,共设计27组不同的清洗方法。采用高效液相色谱-串联质谱法同时测定8种农药的残留量,比较清洗前后的农药残留量作为清洗效果的评价指标。结果以2%碳酸氢钠水溶液为清洗溶剂,在40℃的条件下超声10 min取得的清洗效果最好,能将5种不同的农药残留量降低30%以上。结论该方法设计科学,结果可靠,容易操作,可用于草莓日常清洗的方法,为草莓的食用安全提供了一定的保障。     

纺织材料可生物降解性评价方法

在分析现有可生物降解性评价标准及评价方法的基础上,就纺织材料可生物降解性评价方法的研究情况作了系统的介绍,并就各主要市场对可生物降解及可堆肥材料的要求作了介绍和分析.提出应结合纺织材料特点,积极分析和筛选适用于纺织材料可生物降解性的评价方法与标准,对纺织材料的可生物降解性作出合适的评价.     

几种微胶囊包裹方法对葡萄籽原花青素包裹效果的对比研究

以喷雾干燥法研究了β-环糊精,多孔淀粉-明胶,麦芽糊精-大豆分离蛋白三种壁材的包裹方法对葡萄籽原花青素的包裹效果。结果表明,β-环糊精不适于包裹原花青素;多孔淀粉-明胶包埋原花青素时,以进风口温度200℃,出风口温度60℃的处理得到的包埋率最高,为98,34%;麦芽糊精-大豆分离蛋白也是一种良好的壁材,几乎可以全部包埋原花青素。当进风口温度190℃,出风口温度55℃,进料流量40mL/min时包埋率可达80%以上。     

清洗杀菌方式对鲜切杭白菜保鲜效果的影响

以杭白菜为对象,对新鲜杭白菜进行鲜切处理后,研究不同清洗杀菌方式(次氯酸钠溶液:有效氯为0.1g/L;电解水:pH为2.3;臭氧水:活氧浓度为1.8mg/L)对鲜切杭白菜保鲜效果的影响。结果表明:臭氧水清洗能更好地保持鲜切杭白菜感官品质,使菌落总数维持在较低的水平,显著地延缓抗坏血酸和叶绿素含量的降低(P0.05),有效地延长杭白菜货架期长达6d。     

不同提取方法对橙皮果胶乳化特性的影响

以橙皮为原料采用顺序提取法(热缓冲溶液、螯合剂溶液、稀碱溶液和浓碱溶液)、酸提法和酶提法获得了6种不同性质的橙皮果胶:热缓冲液可溶性橙皮果胶(heat buffer soluble orange peel pectin,HBOP)、螯合剂可溶性橙皮果胶(chelating agent soluble orange peel pectin,CHOP)、稀碱可溶性橙皮果胶(dilute alkali soluble orange peel pectin,DAOP)、浓碱可溶性橙皮果胶(concentrated alkali soluble orange peel pectin,CAOP)、冷冻干燥后酸提取的橙皮果胶(acid extracted soluble orange peel pectin,AEOP)、冷冻干燥后酶处理提取的橙皮果胶(enzymatic extracted soluble orange,EEOP),研究了果胶浓度、p H、Ca2+浓度和温度变化对橙皮果胶乳化特性的影响。结果表明,CAOP的乳化活力和乳化稳定性随果胶浓度增加而提高,在果胶质量浓度为10 mg/m L时达到最大值,仅次于HBOP和CHOP;在p H值3～9或Ca2+摩尔浓度0. 2～0. 8 mol/L时,CAOP乳化活力始终高于0. 05,且在p H 5时,乳化稳定性达到最大,为108 min; 6种果胶在常温下均表现出较好的乳化活力和乳化稳定性;与其他果胶相比,CAOP具有较低的絮凝指数,FI≤279. 09;并且CAOP的粒径很小,最大粒径仅为33. 44μm。综上,CAOP呈现出理想的乳化特性,可以成为食品乳化剂的理想替代品。     

不同工艺条件下食用肉桂油树脂有效成分比较

本文采用气质联用的气相色谱法 ,对超临界二氧化碳萃取法和溶剂法提取的肉桂油树脂与水汽蒸馏法的肉桂精油 ,进行对比分析 ,研究了三者在化合物组成上的差异 ,为肉桂油树脂的质量评价提供了比较可靠的科学依据。     

不同清洗方法对皮蛋破损率影响的研究

目的探索一种可行的原料蛋清洗方式,以便在皮蛋生产中推广使用,满足皮蛋生产过程中的卫生要求。方法在其他工艺流程和工艺条件不变的情况下,采用5种不同的清洗方法对原料蛋进行清洗,并在一年中的4个不同时间,采用3种现有的腌制液腌制后对皮蛋破损率进行监测。结果皮蛋破损率受清洗方式的影响较大,使用传统工艺不清洗方式的破损率最低,经55~60℃热水清洗方式生产的皮蛋破损率次之,40~43℃温水清洗生产的皮蛋破损率最高。结论在腌制前,采用55~60℃热水对原料蛋的表面进行清洗是最有效降低皮蛋破损率的方式。     

不同干燥方式对橘皮精油和黄酮的影响

采用晒干、阴干、烘干及真空干燥4种方式对橘皮进行处理,研究不同干燥方式对橘皮精油含量、精油组分和黄酮含量的影响。结果表明,烘干得到的橘皮精油含量最高为2.11%,其次是晒干(1.91%)、真空干燥(1.95%)和阴干(1.65%)。通过GC-MS分析,新鲜及4种干燥方式得到的橘皮精油共鉴定出23种组分,主要成分为D-柠檬烯。橘皮中的精油组分主要分为6类,分别是萜烯类、醇类、醛类、酚类、醚类及苯类。干燥之后橘皮中的黄酮含量均有所下降,其中阴干橘皮中黄酮含量最高为15.73 mg/g,其次是烘干为15.49 mg/g。综合比较四种干燥方法,烘干干燥时间短,不受天气影响,得到的橘皮精油及黄酮含量均比较高,因此烘干更适合橘皮的干燥。     

不同萃取方式对烘烤花生挥发性物质 提取效果的影响

目的 比较固相微萃取、动态顶空吹扫两种提取方法对烘烤花生的挥发性物质的提取效果。方法 分别优化固相微萃取的萃取纤维头、萃取温度、萃取时间、动态顶空吹扫的吹扫时间、水浴温度、氮气流速等因素, 测定其对烘烤花生挥发性物质的萃取个数、挥发性化合物的总峰面积等指标的影响。结果 顶空固相微萃取法和动态顶空吹扫法得到的有效化合物分别为54和46种; 相对标准偏差分别为17.36%和19.38%。 结论 顶空固相微萃取方法简便、快速、经济安全、无溶剂、选择性好且灵敏度高, 是烘烤花生关键风味物质提取的良好方法。     

纺织品水萃取液pH值测定标准的差异分析

水萃取液pH值是纺织品的一个重要安全环保指标,经过多年的修改和完善,国际上存在多种纺织品水萃取液pH值测定标准.文中介绍了现行有效的4个主要纺织品水萃取液pH值测定标准的差异,并对这些差异可能对测定结果造成的影响进行了分析.     

不同灭菌方法对甜菊叶浸提液灭菌效果及糖甙成分影响

采用两种物理方法(微波、水浴)和3种化学方法(甲醛、次氯酸钙、双氧水)对甜菊干叶提取液进行灭菌,以灭菌效果和对糖甙的成分的影响为指标,选出生产上最适合的灭菌方法。结果表明,水浴加热和微波在90℃温度下处理1h灭菌效果良好,但是在60℃灭菌效果不明显,在同一温度和时间下,微波灭菌比水浴灭菌效果好;化学灭菌法从灭菌效果来看甲醛杀菌能力最强,双氧水其次,次氯酸钙最差;从灭菌处理后糖甙各成分及总甙含量来看,两种物理方法(微波、水浴)和3种化学灭菌剂(甲醛、次氯酸钙、双氧水)对甜菊糖甙成分影响较小。因此,从灭菌效果和对甜菊糖甙成分影响考虑,物理方法中,微波灭菌强于水浴灭菌;化学方法中,甲醛首选,其次是双氧水,再次是次氯酸钙。但是考虑到微波灭菌法成本高和甲醛对人体有害,因此,建议在生产上选用双氧水作为灭菌剂较为合适。     

Removal of residual pesticide, fenitrothion, in vegetables by using ozone microbubbles generated by different methods

The effects of ozone microbubbles (OMB) generated by different methods on removal of residual fenitrothion (FT) in three kinds of vegetables were examined. FT-infiltrated lettuce, cherry tomatoes and strawberries were immersed in solutions containing OMB generated by using a microbubble generator of a decompression-type or a gas-water circulating-type combined with an ozone generator at an initial OMB concentration of 2.0 ppm for 0, 5 or 10 min. Residual FT in each vegetable was removed more efficiently by the OMB treatments with the decompression type than with the gas-water circulation type, showing that the pesticide-removing effect of OMB varies with the method of OMB generation.     

不同方法对黄精浸提液澄清作用的研究

研究了澄清剂法和微滤法对黄精浸提液的澄清效果。通过单因素及正交优化实验,选定澄清剂-壳聚糖法的最佳优化条件为,添加量3%,50℃水浴1h。在微滤法中对不同陶瓷膜孔径进行比较,结果显示,0.5μm孔径陶瓷膜对黄精浸提液有较好的澄清效果。两种澄清方法都能够有效地保留黄精浸提液中的多糖和皂苷等活性成分,操作简单,提高了黄精浸提液的稳定性。      

Evaluation of pork backfat firmness and lard consistency using several different physicochemical methods

A total of 96 pigs were fed on a control diet (barley, wheat, soybean meal) or the control diet supplemented with one of six fats, differing in saturated (SFA), cis‐ and trans‐monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) content, in order to produce backfat widely differing in fatty acid composition. In addition to fatty acid composition, firmness was measured, by means of a puncture test, in the intact outer backfat layer and in lard extracted from the outer layer. Melting behaviour and solid fat content (SFC) were determined by differential scanning calorimetry and crystallisation time with a Rapid Interesterification Control‐Box. Regression analyses revealed that all consistency traits were mainly dependant on SFA content, particularly stearic acid. Cis‐MUFA were the next most decisive for crystallisation time and SFC. The prediction of firmness and SFC at 0 °C was improved when the proportion of PUFA was also considered. The stearic to linoleic acid ratio provided the best prediction of lard firmness. It was concluded that MUFA and PUFA exert specific effects on the different consistency characteristics and not only PUFA but also MUFA should be considered in feeding recommendations for growing‐finishing pigs when lard consistency is to be improved. Copyright © 2004 Society of Chemical Industry