亚硫酸法甘蔗糖厂澄清工艺条件对蔗汁除酚和脱色效果的影响

系统研究甘蔗制糖亚硫酸法澄清工艺条件对蔗汁除酚和脱色效果的影响,澄清工艺单因素试验和正交试验结果表明蔗汁除酚率与脱色率的关系不是简单的正相关关系,而是取决于具体澄清工艺参数的变化;蔗汁澄清最佳工艺条件为P2O5总含量为400 mg/kg,预灰p H为6.8,硫熏强度为18 m L,中和p H为7.2。在此条件下,除酚率和脱色率的平均值分别达57.2%和60.8%。     

超高压与高温短时杀菌对甘蔗汁品质的影响比较

研究了超高压(HHP,500 MPa/4 min)和高温短时(HTST,95℃/15 s)对甘蔗浊汁和清汁p H、可滴定酸(TA)、可溶性固形物(TSS)、总酚、色泽、褐变度、澄清度、浊度和微生物指标的影响,并分析了4℃,贮藏15 d内甘蔗汁品质的变化。结果表明:HTST和HHP处理对甘蔗汁均具有较好的杀菌效果,HHP和HTST甘蔗清汁p H显著降低,HTST甘蔗清汁可滴定酸(TA)含量升高,HHP和HTST对甘蔗清汁和浊汁的可溶性固形物(TSS)和总酚含量无影响,与HTST相比HHP对甘蔗汁颜色的影响较小,HHP处理后甘蔗清汁澄清度升高,甘蔗浊汁浊度下降,HHP甘蔗汁感官性能优于HTST甘蔗汁。经在4℃贮藏15 d,甘蔗浊汁的菌落总数显著升高,但浊汁和清汁的霉菌和酵母菌数基本保持稳定,贮藏期间甘蔗清汁和HTST甘蔗浊汁p H降低,总酚含量均有明显升高,甘蔗清汁的澄清度和甘蔗浊汁的浊度有所降低,HHP甘蔗清汁的b*值和褐变度增加,HTST甘蔗汁颜色稳定。结论:超高压杀菌有利于保持甘蔗汁品质,是适合甘蔗汁的加工技术。     

旱地甘蔗的磷酸亚硫酸法清净处理技术的改进研究

根据我国云南省蔗区旱地甘蔗的特点,探讨了磷酸亚硫酸法工艺的磷酸加入量、预灰pH值、一次加热温度、硫熏强度、硫熏中和pH值、中和汁二次加热温度等六个因素对这类旱地甘蔗蔗汁清净效果的影响情况,并进行了正交试验研究,确定了旱地甘蔗的磷酸亚硫酸法清净处理技术的最适工艺条件,即总磷酸值400mg/kg;预灰pH7.3;一次加热温度70℃;硫熏强度22g SO2/L;硫熏中和pH6.7;中和汁二次加热温度100℃。     

浅谈甘蔗制糖中和汁磷酸值的测定

在甘蔗制糖工艺中,中和汁中磷酸值是否准确直接关系到整个沉清效果的好坏.《甘蔗制糖化学管理分析方法》中原始甘蔗蔗汁中的磷酸量的测定方法要求所配制的样液经过滤后检测磷酸含量,此法在对于经预灰处理,同时加入磷酸的混合物料（中和汁）中的磷酸量的测定时,其值将是不准确的.经过多年的实践,摸索出一种有效检测此种混合物料中磷酸量的方法,本文概述了其合理性与适用性,以供广大甘蔗制糖厂家在沉清工段参考使用,更有利于我们掌握沉清效果,提高产品质量,更利于节约原辅料的用量,以降低生产成本.     

N,O-羧甲基壳聚糖澄清甘蔗混合汁的工艺研究

研究采用N,O-羧甲基壳聚糖对甘蔗混合汁进行澄清处理,考察了磷酸用量、羧甲基壳聚糖用量、二次加热温度、絮凝剂PAM用量等因素对澄清效果的影响,通过正交试验优化澄清工艺,在磷酸用量(以P2O5总含量计)350 mg/kg蔗汁、羧甲基壳聚糖用量500 mg/kg蔗汁、二次加热温度75℃、絮凝剂PAM用量3 mg/kg蔗汁条件下,纯度差和脱色率的平均值分别为1.76%和65.72%。结果表明,N,O-羧甲基壳聚糖对甘蔗混合汁具有良好的澄清效果,为探索蔗汁清净新工艺提供了理论依据。     

一种甘蔗混合汁无硫二步澄清工艺优化研究

以石灰、磷酸、单宁和Ca(HCO_3)_2作为澄清剂对甘蔗混合汁进行二步澄清处理,通过单因素试验和正交试验确定第二步澄清最佳工艺参数。二步澄清最适工艺参数反应pH 8.6,单宁用量为150 mg/L,1.66%的Ca(HCO_3)_2溶液用量为10 mL/100 mL蔗汁。无硫二步澄清工艺的澄清效果与亚硫酸法的没有显著性差异(p0.05),满足了白砂糖生产的工艺要求,可解决了我国白砂糖含SO_2问题,对提高了我国食糖食用安全性具有积极意义。     

气浮清净工艺处理甘蔗糖液的试验研究

对亚硫酸法清净甘蔗糖液中应用的糖浆气浮、清汁气浮、预灰汁气浮、中和汁气浮等几种气浮清净工艺进行了试验研究,分析了气浮工艺的可行性,并探讨了糖浆气浮清净工艺的条件。结果是糖浆气浮、清汁气浮、中和汁气浮都有较好的清净效果,糖浆气浮适宜工艺条件是:磷酸加入量为200～300mg/kg,上浮糖浆pH6.4～6.6,上浮糖浆温度80～85℃。     

甘蔗混合汁亚硫酸法澄清过程中Zeta电位的研究

本文系统地研究了混合汁亚硫酸法絮凝澄清过程中Zeta电位的变化规律。在考察氢氧化钙、亚硫酸、磷酸以及絮凝剂等因素对甘蔗混合汁Zeta电位影响的基础上,研究了亚硫酸法工艺中预灰、硫熏中和、絮凝等步骤中混合汁Zeta电位的变化规律。结果表明：甘蔗混合汁Zeta电位的绝对值均随着氢氧化钙、亚硫酸、磷酸以及絮凝剂加入量的增加而减小,当达到最小值后又开始出现增大的趋势;在亚硫酸法絮凝澄清过程中,混合汁Zeta电位的绝对值不断减小,其中,预灰过程中变化较小,硫熏中和过程中降低幅度较大,絮凝过程中缓慢减小到最小值;阳离子聚丙烯酰胺相对于阴离子聚丙烯酰胺絮凝剂,Zeta电位绝对值降低程度更大,絮凝效果更好。本研究结果从Zeta电位的角度较好地揭示了亚硫酸法絮凝澄清过程的本质。     

资源化利用磷酸制备D-木糖和L-阿拉伯糖的研究

以蔗渣为原料,经水解、水解液磷酸根沉淀、纯化、制备,得到D-木糖、L-阿拉伯糖。结合甘蔗制糖工艺,磷酸根沉淀经酸溶解处理后,作为甘蔗制糖过程必须使用的加工助剂加入到蔗汁中进行资源化再利用。按照影响酸催化水解的主要影响因素:水解温度(A)、水解时间(B)、酸浓度(C)、液料比(D)进行试验并扩大中试,在最佳工艺条件下L-阿拉伯糖得率为4.20%,木糖得率为26.02%。     

响应面法优化甘蔗果酒发酵工艺

甘蔗含糖量高达17%~18%,富含多种营养物,可以作为原料酿造营养型果酒。为了研究甘蔗果酒发酵规律,以甘蔗汁为原料,在发酵时间、初始p H、发酵温度和初糖浓度4个单因素试验基础上,应用Design-Expert.V8.0.6软件中Box-Behnken试验设计建立回归模型,对甘蔗果酒的发酵工艺条件进行响应面分析优化。结果表明:甘蔗果酒发酵的最佳工艺条件为:发酵时间5.5d、初始p H4.95、温度26.5℃、初糖浓度26.5°Bx。在此优化条件下,得到甘蔗汁发酵液酒精体积分数达到14.15%vol。     

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.     

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.     

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.     

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.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.