绵羊皮两步法脱脂的工艺优化

介绍了绵羊皮两步法脱脂工艺的优化。通过对脱脂前后皮样油脂含量检测和组织切片染色观察等的分析,得到第一步脱脂的最佳工艺条件为:碱性脂肪酶浓度15 u/mL,温度43℃,pH 10.0,时间120 min,采用此工艺,脱脂率达32%左右;第二步脱脂的最佳工艺条件为:脱脂剂FG-B浓度4 g/L,温度43℃,pH10.0,时间120 min,采用此工艺,累计脱脂率达到58.9%。组织学观察结果表明,碱性脂肪酶可以分解脂腺中的脂肪,使绵羊皮乳头层产生一些空腔和腺体管道,有利于进一步脱脂,减少脱脂剂的使用。     

碱性脂肪酶在兔皮脱脂工序中的应用

通过测定碱性脂肪酶在兔皮脱脂中的应用确定了脱脂工序中脂肪酶的最佳使用条件:脂肪酶的最佳使用温度为30-35℃,使用pH 7.5左右,用量1 g/L,时间约为1 h,与脱脂剂结合使用的时候脱脂效果更好,使油脂轻松释出,加快脱脂的进行。     

复配脂肪酶Esm脱脂工艺研究

对复配脂肪酶Esm的脱脂性能及其脱脂工艺进行了研究。用索氏抽提法、组织切片观察和体视显微镜观察共同表征了其脱脂性能。结果表明：复配脂肪酶Esm脱脂效果优于在相同工艺条件下等量的化学脱脂剂,且在比Leveking-P1000用量少时脱脂效果仍占优势。对不同酶脱脂工艺的脱脂效果研究发现：复配脂肪酶Esm在浸水、脱灰、软化阶段脱脂效果较好,尤其是加强脱灰阶段的复配脂肪酶处理。脱脂效果的改善更明显。工艺优化试验筛选出了最佳酶脱脂工艺方案2：在主浸水、浸灰、复灰、软化工序分别加入0．3％复配脂肪酶Esm,脱灰工序加入0．6％复配脂肪酶Esm。对由最佳酶脱脂工艺方案2、经复配脂肪酶Esm脱脂的成品革进行质量性能测试发现：成革的收缩温度、抗张强度、断裂伸长率及撕裂强度,均满足羊服装革的行业标准;染色均匀性、手感以及粒面细致性均能满足对绵羊服装革的要求。因而,复配脂肪酶Esm可用于制革生产的脱脂。     

毛革两用绵羊皮脱脂工艺研究

脱脂是毛革两用绵羊皮制造过程中一个关键工序。本文使用了碱性脂肪酶与纯碱、表面活性剂协同脱脂，结果表明，碱性脂肪酶的使用有助于皮内脂腺的破坏，使油脂容易释放出而达到脱脂的目的。此外，本文还研究了毛革两用绵羊蓝湿皮在不同温度下脱脂，脱脂温度越高油脂脱除效果越佳，蓝皮的最佳脱脂温度为55—60℃。     

碱性脂肪酶应用于猪皮脱脂的探索

我厂生产的碱性脂肪酶是一种在碱性条件下能加速脂肪酸甘油脂水解的高效生物催化剂。将它作为制革工业的一种新型脱脂剂,可以取得明显的技术经济效果。一、碱性脂肪酶脱脂的成革质量脱脂不好,势必影响一系列后继工序的正常进行。并可能造成剖层不匀、染色色花、革身软硬不一乃至涂饰不牢等后患。我们通过小试,把握了碱性脂肪酶对动物油脂的较强的分解能力,首先应用于含油脂量较     

猪皮的不同脱脂方法对胶原提取率的影响

分别用4种有机溶剂、2种非离子型脱脂剂、不同用量的脂肪酶、非离子型脱脂剂AXAUT-50和异丙醇两步法、非离子型脱脂剂AXAUT-50和脂肪酶两步法,脱除新鲜猪皮中的脂肪。对脱脂后的碎皮块提取胶原,结果表明:用单一试剂脱脂时,2种非离子型脱脂剂的脱脂效果最好,脱脂率均高达67%以上,相应胶原提取率也在22%以上。两步法脱脂的效果比任何单一试剂脱脂的效果都好,尤其是AXAUT-50和异丙醇两步脱脂,其脱脂率高达90%以上,相应胶原的提取率也高达28.52%。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)谱图,显示了用不同的方法脱脂后所提取的胶原保留了天然的三股螺旋结构,黏度法测得猪皮胶原的变性温度为35.7℃。     

制革实用技术问答--色差、花差、色斑以及色牢度等(Ⅲ)

问题11:如何解决绵羊皮色花问题?观点:原因:①原皮脱脂不好,后期出现色花;②后期加脂剂的乳化分散不好导致吸收不好出现油花;③蓝湿革存放时间过长,革边上积累铬液多,也可能造成染色加脂时出现色花。措施:①原皮油脂没脱干净的,加强前期脱脂。蓝湿革用F335(渗透脱脂剂)、乳化脱脂剂、D G脂肪酶处理2 h后水洗;检测革中的油脂含量(达到4%以下),假如油脂含量还是太高的话,建议出鼓削匀后再重脱一次脂。     

脂肪酶对皮内油脂催化水解的特性及其脱脂效果

以富含油脂的绵羊皮粉为底物,研究了脂肪酶对皮内油脂的催化水解特性及脂肪酶脱脂效果。结果表明,脂肪酶对皮粉内油脂的催化水解作用受到其产物脂肪酸的抑制;当脂肪酶水解皮内油脂生成的脂肪酸的浓度达到1500μmol/g油脂时,对脂肪酶产生明显的抑制作用;当脂肪酸浓度达到2500μmol/g油脂时,脂肪酶的作用几乎被完全抑制,皮内油脂的最大水解度为70%左右。酸性和中性条件下的单独脂肪酶处理并不能去除皮内的油脂类物质,脂肪酶处理后用适当的碱洗(碳酸钠溶液洗涤),可完全除去脂肪酶的水解产物,用脱脂率达到66%,再结合少量表面活性剂的乳化作用,脱脂率可提高至75%,脱脂效果优于传统的皂化法和乳化法。     

柴油脂肪酶ZG的制革应用性能研究

用于制备生物柴油的脂肪酶ZG能够水解脂肪,针对其基本酶学性能和对制革原料皮的脱脂性能进行研究。结果表明:酶的最适温度、pH分别为60℃、7.0;分别在40℃下保温2h后或在pH值5~11缓冲液中25℃下放置2h后,该酶活力仍保持在80%以上,表明在40℃左右酶的温度稳定性较好,其pH适用范围也较广;Ca~(2+)对脂肪酶ZG具有明显的激活作用,而Na~+对其酶活力影响不大。因此初步确定该酶的基本性能能够满足制革原料皮的脱脂工艺要求。对脱脂绵羊皮油脂含量分析表明:其脱脂效果可以与化学脱脂剂TB媲美,但逊于进口脂肪酶G20。表明脂肪酶ZG用于制革原料皮的脱脂工序是可行的,对其进行性能优化后使其成为制革专用脱脂酶的前景看好。     

碱性脂肪酶Greasex 50L在猪皮上的脱脂作用

对碱性脂肪酶 Ｇｒｅａｓｅｘ ５０Ｌ在猪皮上的脱脂作用进行了初步研究,将酶处理前后及有无酶处理的皮进 行了油脂抽提试验。结果表明：通过 Ｇｒｅａｓｅｘ ５０Ｌ的作用,皮的油脂含量（二氯甲烷浸提物）显著降低。通 过对试验方案的多次筛选,得到比较适于碱性脂肪酸 Ｇｒｅａｓｅｘ ５０Ｌ作用的工艺条件,油脂去除率可达 ６０％。     

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.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

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.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.