冷冻调理龙虾的制备及冻结方式对其品质的影响

以龙虾为原料,采用正交试验法,以感官评分为标准,确定调理龙虾调味液的最佳配方为:白砂糖1.5 g,花椒粉0.4 g,酱油3.3 g,辣椒粉2.2 g。采用-18、-68℃2种冻结方法,研究不同冻结方式对冷冻调理龙虾品质的影响。结果表明,不同冻结方式下虾体中心温度、咀嚼度、微观结构有显著差异,-68℃冻结的虾体中心温度通过0~-5℃的时间仅为6~10 min,而-18℃冻结的虾体中心温度通过0~-5℃的时间为60~80 min;-68℃冻结下调理龙虾的咀嚼度显著低于-18℃冻结;-18℃冷冻的调理龙虾肉组织结构松散、纹理模糊,而-68℃冻结的龙虾肉组织分布均匀,纹路清晰。由此可见,低温速冻有利于保持冷冻调理龙虾的品质。采用低温静置、室温静置、室温浸渍和微波4种解冻方法,研究不同解冻方式对产品品质的影响,得出室温静置解冻感官评分最高,但耗时较长,而微波解冻感官评分稍低,但耗时最短,在实际应用中可根据需要选择解冻方式。     

速冻方式与温度对鲍鱼品质的影响

为了研究不同速冻方式和冻结温度对鲍鱼冻结过程中的品质影响程度、产生原因及机理,本文以鲜活鲍鱼为研究对象,对比采用2种速冻方法(空气速冻和液体速冻)、3种冻结温度(-20℃、-40℃、-60℃)进行冷冻,以蛋白质冷冻变性程度、肌肉组织结构和弹性作为理化和质构特性评价指标。试验结果表明:液体速冻的冻结速率始终比空气速冻高10倍左右,盐溶性蛋白溶解度下降率低2%左右,Ca2+-ATPase活性下降速度与Mg2+-ATPase活性上升速度均略缓慢,蛋白质变性程度低,解冻后鲍鱼肌肉组织间空隙小,弹性好;冻结过程中,冻结温度越低,冻结速率越快,盐溶性蛋白损失越少,蛋白质变性程度和解冻后的弹性无明显变化;综合考虑冻结速率、品质、能耗等因素,认为液体速冻是适合鲍鱼的速冻方法,-60℃液体速冻是相对最佳的速冻工艺。     

冷冻预处理对刺葡萄榨汁品质的影响

冷冻预处理有利于提高葡萄榨汁出汁率,但冷冻预处理对葡萄榨汁后汁液的品质影响目前尚不清晰。将葡萄果粒在-30℃条件下冷冻至中心温度-21℃,解冻后榨汁作为试验组,将果粒4℃条件贮藏后榨汁作为对照组,研究冷冻预处理对刺葡萄汁花色苷、色差、总糖、总酸等指标的影响。结果表明,葡萄汁在4℃条件下贮藏30天后,对照组与试验组中的花色苷含量、色差、总糖、总酸含量差异均不显著。说明冷冻预处理对刺葡萄汁品质不会产生不良影响。     

猕猴桃冷冻破壁离心取汁工艺

根据缓慢冻结破坏细胞壁的原理,采用冻融离心取汁新工艺制取猕猴桃果汁,对冷冻破壁和离心工艺参数进行单因素和正交试验分析。结果表明：冷冻破壁离心取汁工艺所制备的果汁在出汁率、VC 含量、透光率及色泽方面都明显优于传统榨汁工艺,最佳工艺条件为切片厚度0.6cm、－ 14℃冷冻10h、30℃解冻30min、3000r/min 离心20min、100 目过滤。     

液浸速冻对牡蛎水分迁移及品质的影响

为寻求高效的牡蛎冷冻方式,研究了液浸速冻对牡蛎水分迁移及品质的影响,优化了液浸速冻牡蛎的冻结温度,并在此基础上通过低场核磁共振分析液浸速冻对牡蛎水分状态、含量及分布的影响。结果表明：－35 ℃液浸速冻的牡蛎解冻后仍保持良好的持水能力和弹性,蛋白质无明显变性。相比－18 ℃静置冷冻、－35 ℃气流冷冻和－80 ℃超低温冷冻,－35 ℃液浸速冻的冻结速率最大,高达13.03 cm/h,是－35 ℃气流冷冻和－80 ℃超低温冷冻的5～6 倍,属超速冻结方式,且液浸速冻牡蛎的不易流动水损失最少,解冻后其核磁共振图像显示牡蛎肉体内部基本无汁液流失。     

水代法制备核桃油过程中冷冻解冻破乳工艺的优化

为考察冷冻温度、冷冻时间、解冻温度、解冻时间对水代法提取核桃油产生的乳状液的影响,在单因素基础上,通过正交试验对冷冻解冻破乳乳状液工艺进行优化。结果表明,冷冻解冻乳状液破乳的最佳工艺为:冷冻温度-20℃,冷冻时间10 h,解冻温度50℃,解冻时间15 min。在此条件下进行验证试验,乳状液破乳率高达93.27%。     

不同冷冻贮藏温度对椰肉保鲜效果和加工特性的影响

为尝试利用冷链贮运技术保障我国椰子加工原料供给的问题,采用速冻温度(-80℃和-40℃)和缓冻温度(-18℃和-10℃)通过自然解冻的方法研究椰肉解冻后的保鲜效果和加工特性。冷冻贮藏后的椰肉没有产生异味,保鲜效果良好,随着冷冻温度的升高椰香味稍微减少,冷冻过后椰肉颜色有少量变黑。速冻条件下的椰肉和鲜椰肉的内表面组织结构差别不大,而在缓冻条件下的椰肉内表面均出现裂缝。随着冷冻温度的升高,汁液流失率和浸出油含量均呈增加趋势,而椰肉亮度、榨汁率、pH和榨汁后的椰浆稳定系数均呈降低趋势,但两个速冻条件之间的椰肉汁液流失率、浸出油含量、椰肉亮度、p H和椰浆稳定系数之间差异不显著,两个缓冻条件之间也不显著。此次试验可为椰肉冷链贮运技术的应用提供参考。     

液氮喷雾速冻及梯度解冻在荔枝品质保鲜上的优势

为探究荔枝的冻融特性,确定其适宜的冻融方式,该研究通过液氮喷雾速冻(-40℃/-60℃/-80℃/-100℃)和梯度解冻(-20℃/0℃/5℃/4℃/25℃)对荔枝冻融特性和品质的影响,并以传统冰柜冻结、浸渍冷冻、室温解冻为对比.结果表明:在-20～-100℃范围内,温度越低,穿过最大冰晶生成带时间越短,对冻结荔枝的保...     

冷冻及解冻处理对肌原纤维蛋白理化性质的影响

研究不同的冻结温度（-18 ℃和-50 ℃）和解冻方式（微波解冻、空气解冻及4 ℃解冻）对猪肉肌原纤维蛋白含量和理化特性的影响。结果表明,在不同冻结温度与解冻方式下,肌原纤维蛋白的含量、溶解性、乳化活性、乳化稳定性、起泡性及起泡稳定性均降低,表面疏水性增加。其中,采用-18 ℃冻结,微波解冻处理的肌原纤维蛋白与对照组相比,其溶解性、乳化性、乳化稳定性、起泡性及起泡稳定性分别降低了38.7%、16.5%、28.3%、39.6%和17.3%;采用-50 ℃冻结,4 ℃解冻的蛋白其含量（6.32%）、溶解性（22.05%）、乳化性（7.89 m2/g）、乳化稳定性（32%）、起泡性（30.95%）及起泡稳定性（62.25%）与其他处理对应的各指标相比,理化特性均保持较好。不同的冷冻和解冻条件下,肌原纤维蛋白各指标之间的变化相互关联。     

普洱茶籽乳状液的冷冻微波解冻破乳工艺优化

对水酶法提取普洱茶籽油过程中形成的普洱茶籽乳状液的冷冻微波解冻破乳工艺进行研究。考察了冷冻时间、微波解冻功率、微波解冻温度及微波解冻时间对破乳率的影响,得出冷冻微波解冻最优破乳条件为:-20℃冷冻时间4 h,微波解冻功率500 W,微波解冻温度50℃,微波解冻时间30 min。在最优冷冻微波解冻破乳条件下,破乳率可达到97.53%。     

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.     

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.     

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.     

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