生物发酵处理对小米淀粉分子结构及糊化特性的影响

采用0.2 g/100 m L NaOH溶液提取发酵后的小米淀粉,研究自然发酵及优势菌(乳酸菌、酵母菌)发酵后对小米淀粉颗粒特性、结晶度、官能团、分子质量、糊化及老化特性的影响。结果如下:乳酸菌、酵母菌发酵后,淀粉颗粒表面有明显的侵蚀迹象,而自然发酵淀粉颗粒表面侵蚀迹象较轻;乳酸菌发酵后小米淀粉的结晶度较自然发酵增加1.49%而酵母菌发酵减少0.33%;发酵并未改变小米淀粉官能团区的峰位,但特征峰强度减弱,乳酸菌、酵母菌发酵后小米淀粉指纹区图谱消失;未发酵小米淀粉重均分子质量为1.5×10~4~5.9×10~5 g/mol,自然发酵分子质量在2.1×10~4~5.4×10~5 g/mol,乳酸菌发酵分子质量为1.6×10~4~5.3×10~5 g/mol,酵母菌发酵分子质量为1.6×10~4~4.7×10~5 g/mol,乳酸菌、酵母菌发酵后支链淀粉长链及直链淀粉比例减少而中间及短支链淀粉的比例相对增加;乳酸菌、酵母菌发酵96 h糊化温度较自然发酵下降0.84℃和1.13℃,热焓值上升1.00 J/g和0.78 J/g;二者的回生值较自然发酵分别下降743、471 mPa·s。自然发酵的优势菌(乳酸菌、酵母菌)使小米淀粉的分子结构、糊化及老化特性发生明显变化,并在小米自然发酵过程中起主导作用。     

面条熟化工艺研究进展

阐述了面团熟化的机理以及在熟化过程颗粒中淀粉发生的变化,总结了前人对熟化工艺的研究成果,并对现在工业生产中常用的面团和面带熟化工艺做了介绍。针对原面条评价标准主观性过强及改进后缺乏统一标准体系的特点,有必要建立一个同仪器评价相结合的标准体系。     

糙米酵素发酵剂筛选分离及应用研究

从自然发酵面团中分离乳酸菌和酵母菌，并对分离的菌种进行形态观察和产酸特性实验，对筛选出的单菌种进行复壮、扩大培养。将培养的单菌种乳酸菌和酵母菌分别加入糙米培养基中，测定各自的产酸效果，挑选出产酸量较高的乳酸菌和酵母菌。与直投式酵母菌发酵为对照，比较分离的酵母菌和乳酸菌在糙米发酵中的产酸效果。结果表明，从自然发酵面团中分离得到的菌种产酸效果优于直投式酵母菌，分离得到的乳酸菌和酵母菌最佳配比为1：2～1：3。     

酵母菌与乳酸菌发酵对小米淀粉粘度的影响

自然发酵受环境和微生物的影响大,难实现发酵产品的大规模生产。故研究自然发酵优势菌对小米淀粉的影响很有必要。选取内蒙古赤峰生产的黄金苗小米为原料,利用自然发酵纯化的酵母菌与乳酸菌为菌种进行纯种发酵96 h,并且与自然发酵后的小米淀粉比较,分析淀粉的粘度、衰减值和回生值的变化。采用0.2 g/100 m L的Na OH溶液提取3 h的方法来提取发酵后小米中的淀粉,并对其发酵液中固形物的含量、p H、淀粉的粘度特性、偏光十字进行测定。结果表明,三种发酵方法所得的发酵液中总固形物的含量都增加;较自然发酵相比,发酵前24 h乳酸菌和酵母菌发酵液中的p H下降迅速,之后变化缓慢;淀粉粘度特性表明,乳酸菌和酵母菌发酵终止时,其粘度的起始温度、衰减值、回生值较自然发酵相比都下降,峰值粘度较自然发酵相比都上升,乳酸菌发酵和酵母菌发酵的最终粘度与自然发酵相比有所增加,偏光十字显示无论是自然发酵酵母菌发酵还是乳酸菌发酵,发酵后的淀粉颗粒仍具有偏光十字,说明发酵未改变淀粉的结晶结构。     

优势微生物组成对米发糕品质的影响

接种酵母菌和乳酸菌复合菌株或酵母菌和根霉复合菌株制作米发糕,采用动态流变仪、氨基酸自动分析仪、气相色谱-质谱仪分析米发糕的质地、滋味和气味特征,研究优势微生物组成对米发糕品质的影响,为米发糕的品质控制提供依据。结果表明:微生物组成对米发糕品质有显著影响,接种酵母菌和乳酸菌复合菌株的米浆糊化温度较低,米发糕质地较柔软,甜味和鲜味氨基酸含量较高,挥发性物质种类较丰富,其特征香气物质为苯乙醇、辛酸乙酯、癸酸乙酯和棕榈酸乙酯。大米发酵体系中酵母菌和乳酸菌的协同作用优于酵母菌和根霉,使大米淀粉、大米蛋白质的水解程度更高,产生较多的呈味氨基酸和香气物质。     

酸面团发酵过程中蛋白质分解及多肽形成的变化规律

本文以小麦粉,酵母菌和植物乳酸菌M616(Lactobacillus plantarum M616)为原料制备酸面团,酵母发酵面团以及乳酸菌发酵面团,研究酸面团发酵过程中蛋白的分解及肽的形成规律,采用SDS-PAGE分析酸面团发酵过程中蛋白质的组成变化,利用Bradford法分析蛋白质含量的变化,并通过HPLC研究蛋白组分降解形成多肽的含量变化。结果表明,酵母菌对面团中蛋白质几乎没有降解作用,植物乳酸菌M616在面团发酵过程中对面团蛋白具有较强的降解作用,表现为各蛋白含量随发酵时间的进行逐步减少,且在4~10 h之间变化最为显著。其中可溶性蛋白和中分子量麦谷蛋白的降解最为明显,醇溶蛋白含量在0~10 h之间逐渐增加后逐渐减少。对发酵前后多肽含量变化分析发现植物乳酸菌可以明显促进面团中多肽的形成和含量的增加。     

酸面团中的优势微生物及其相互作用研究进展

酸面团是由谷物与水混合，经微生物发酵形成的传统面制食品发酵剂，广泛应用于各种面制品的制备。酸面团是一种复杂的微生物生态系统，其中以乳酸菌和酵母菌为主，它们的生长和相互作用会影响酸面团中微生物的结构和功能，最终赋予发酵面制品更好的加工特性、营养特性和感官特性。该文对酸面团发酵过程中微生物的动态变化以及成熟酸面团中的优势微生物进行了概述，并探讨了优势微生物之间的相互作用对酸面团产品品质的影响，以期从微生物层面了解酸面团对面制品产生积极影响的原因，为酸面团的发展提供理论基础。     

微生物发酵法改良甘草感官品质的研究

研究了微生物乳酸菌和酵母菌在二次发酵法下改良甘草提取液的感官品质。实验结果表明,经过乳酸菌发酵8h和酵母菌发酵2h后,甘草提取液的感官品质达到最佳。经过乳酸菌和酵母菌发酵后,甘草的腥味消失,口感变成具有酸爽的杀口感,气味具有酒香味。因此,经过乳酸菌和酵母菌二次发酵法后,甘草的感官品质得到明显改善。     

中国不同地区老酵头对馒头质构和感官品质的影响

目的探讨中国不同地区传统老酵头对馒头品质特征的影响,筛选产品品质较为优良的老酵头。方法收集10个地区的传统面食发酵剂为实验材料制作老酵馒头,测定不同地区老酵面团在发酵过程中微生物的变化及馒头的品质指标,并进行感官评价。结果不同地区老酵馒头的品质指标间具有显著性差异(P0.05),老酵头制作面团发酵过程中不同地区间酵母菌和乳酸菌的生长趋势相似且具有一定的规律性,在发酵前期,酵母菌迅速生长至面团成熟期后,其数量趋于稳定;乳酸菌在发酵前期经过短暂的适应期后进入快速生长期,至面团成熟期后乳酸菌数量显著下降。综合馒头的质构指标、物性指标及感官评价来看,5#老酵头制作出的馒头其综合品质最佳,感官评分最高为89分。结论本研究结果为传统发酵剂在馒头工业化生产中的合理利用提供了理论依据。     

黄水中乳酸菌的筛选及应用(一)

黄水是白酒酿造过程中的副产物，其含有丰富的乳酸菌、丁酸菌、己酸菌、酵母菌等微生物资源。从黄水中分离、筛选乳酸菌的结果表明，分离、筛选得的菌株在黄水中利用淀粉和残糖发酵产生乳酸的能力明显高于直接从黄水中分离得的乳酸菌。     

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.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.     

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%.