腐乳品质改善的研究进展

腐乳是通过微生物发酵而成的一种滋味鲜美,营养丰富的佐餐食品,具有独特的风味以及良好的生理保健功能.结合国内外对腐乳的研究,主要对腐乳的生产工艺、微生物种类、风味物质、后发酵期的缩短以及腐乳生产和安全性控制进行了综述.相信随着人们健康意识的提高以及现代科学技术的应用,腐乳将具有更为广阔的发展前景.     

高温条件下混菌发酵对腐乳风味化学组分影响的研究

以35℃高温前酵条件下毛霉、根霉复合酿造腐乳及相同条件下毛霉单菌酿造腐乳为研究对象,对后酵成熟过程中主要化学组分、感官评分及蛋白质降解情况进行了测定。并以常温前酵毛霉单菌酿造的腐乳为阳性对照,对后酵9周的两组样品的主要风味成分进行了分离鉴定。结果表明:经高温前酵的混菌酿造腐乳的氨基酸态氮、水溶性蛋白及可溶性无盐固形物等化学组分与感官评分一直优于相同条件下单菌酿造腐乳。经高温前酵的混菌酿造腐乳比同条件下单菌酿造腐乳的大分子量蛋白质降解更为迅速彻底。高温前酵混菌酿造腐乳的风味物质为43种,高温前酵单菌酿造腐乳的风味物质为33种,而常温前酵单菌酿造腐乳的风味物质为42种。     

市售茨河花色腐乳和红方腐乳微生物菌群及风味物质的比较分析

基于MiSeq高通量测序技术对湖北省谷城市茨河花色腐乳和全国不同地区的红方腐乳的微生物菌群进行了分析,同时使用GC-IMS对腐乳的气味基础—挥发性有机物进行了分析。结果表明,花色腐乳与红方腐乳的细菌与真菌菌群结构存在显著差异(P<0.05),前者的生物标志菌属为假单胞菌属(Pseudomonas),而红方腐乳的生物标志菌属为红酵母属(Rhodotorula),曲霉属(Aspergillus)和明串珠菌属(Leuconostoc)。GC-IMS结果显示,两种腐乳的小分子酯类风味物质种类最丰富,醛类物质在红方腐乳中富集,而酮类物质在花色腐乳中富集。另外,红方腐乳的特征风味物质为乙醇、2-甲基丁醛,2-甲基异丙醛等,而花色腐乳的特征风味物质为乙醛,丙烯酸乙酯,柠檬烯等。另外,威克汉姆酵母属(Wickerhamomyces)和毛霉(Mucor)与多种风味物质呈正相关,因此在花色腐乳的生产中具有开发与应用的潜力。     

克东腐乳发酵过程中挥发性风味物质分析

克东腐乳是以微球菌为主要菌系发酵而成的细菌型腐乳,具有独特的质地和风味。本文采用同时蒸馏萃取法(SDE)提取,并结合气相色谱-质谱联用(GC-MS)技术对克东腐乳挥发性风味物质进行跟踪萃取检测研究,样品包括豆腐白坯、发酵液及生产过程中腐乳块和汤料,综合分析各种风味成分的产生情况及含量变化,并且与传统毛霉腐乳的挥发性风味物质种类及含量进行比较。分析表明随着发酵时间的延长,检测出的挥发性风味物质种类不断增加,酸、醛、酮、醇等类物质不断产生,而且相应的百分含量逐渐增加;酯类始终是主要的的风味物质,而在整个过程中酯类物质所占的百分比呈下降趋势。以克东腐乳为研究对象,揭示细菌型腐乳生产过程中风味物质的变化规律,为中国传统发酵食品建立基础性数据资料。     

腐乳的白点问题研究进展

腐乳是中国传统发酵豆制品,具有风味良好,营养丰富等特点.本文综述了我国腐乳的生产历史及其分类.提出了腐乳生产中常见的问题,如发霉,白点,变色等.特别针对严重影响腐乳外观的白点问题进行了论述,分析了其成分为酪氨酸,以及白点的形成机理,最后提出了相关的解决办法.     

红腐乳发酵过程中菌群结构与风味相关性研究进展

红腐乳是一种在半开放式环境中发酵生产的大豆制品,由于在后发酵阶段加入特有的红曲汤料,形成了其独特的风味。在红腐乳发酵过程中除了接种的毛霉外,还有包括细菌在内的外界微生物进入,从而形成一个复杂的菌群结构,对红腐乳风味物质的形成起重要作用。该文主要综述了红腐乳的风味形成机制、微生物组成、风味成分、微生物与风味之间的相关性研究进展,为通过微生调控手段来改善红腐乳品质提供重要参考。     

大豆红曲对红腐乳风味及感官品质的影响

该研究以市售红腐乳为对照，采用大豆红曲（RFS）替代红曲米制备红腐乳，采用分光光度法、高效液相色谱法及气相色谱-质谱联用法分别测定红腐乳的色价、莫纳可林K含量及挥发性风味物质，并对红腐乳进行感官评价，考察大豆红曲对红腐乳品质的影响。结果表明，大豆红曲红腐乳的色价（3.76 U/g）与市售红腐乳无显著差异（P<0.05），莫纳可林K含量为0.43 mg/g。红腐乳中共检测出26种挥发性风味物质，大豆红曲红腐乳与市售红腐乳的共有挥发性风味物质主要为己酸乙酯、庚酸乙酯和十四酸乙酯。与市售红腐乳相比，大豆红曲红腐乳中风味物质类别（7种）较多，其特有风味物质为甲氧基苯肟与戊基苯，其中甲氧基苯肟来自大豆红曲。以大豆红曲为辅料所得红腐乳可满足红腐乳感官要求，感官评分为40.57分。     

红腐乳后酵期风味物质与细菌菌群分析

为探究目前市场中红腐乳后酵阶段风味物质与菌落演替之间的关系,采用顶空固相微萃取-气相色谱-质谱联用技术、反相高效液相色谱和邻苯二甲醛柱前衍生化检测相结合的方法,检测腐乳中挥发性风味物质及氨基酸含量。共检测出挥发性风味物质50 种,主要为酯类20 种、醇类9 种,通过气味活性值分析得到主要风味物质为苯乙醇、1-辛烯-3-醇、乙酸乙酯等,大部分酯类、萜烯类、呋喃类等风味物质种类和含量随发酵进行升高,烷烃类及部分酯类物质变化不明显。对不同阶段的后酵期红腐乳游离氨基酸含量进行分析测定,其中总游离氨基酸含量随发酵进行而提高。采用高通量测序法分析细菌菌落,得知红腐乳中优势菌群为芽孢杆菌（Bacillus）、肠杆菌（Enterobacter）、不动杆菌（Acinetobacter）、四联球菌（Tetragenococcus）等。细菌多样性在发酵过程中显著提高;Bacillus相对丰度随发酵进行明显降低,乳球菌（Lactococcus）、Tetragenococcus相对丰度随发酵进行提高;Enterobacter相对丰度在前中期明显提高,中后期下降。将游离氨基酸、部分挥发性风味物质与菌群进行Pearson相关性分析,结果表明,红腐乳后酵期氨基酸的产生与Enterobacter呈明显正相关,但Enterobacter与大部分香味化合物负相关;Bacillus与多种香味酯类化合物正相关;其他菌种如Lactococcus、Acinetobacter也在红腐乳后酵期提供良好风味。     

腐乳挥发性成分的研究

大豆发酵食品中挥发性成分直接影响产品的风味,文中对中国传统大豆发酵制品--腐乳的挥发性成分的种类、风味成分保留指数与挥发性成分的关系、影响腐乳挥发性成分的因素等的研究进行了综述.     

不同香型白酒酿造腐乳风味对比研究

为了解不同香型白酒原料酿造腐乳风味差异,采用感官评分、全二维气相色谱-质谱结合主成分分析等对风味特征和挥发性组分进行比较分析。结果表明,6种香型白酒酿造的腐乳感官综合评价最佳的为米香型样品,最差的为酱香型样品。6种腐乳共鉴别出125种风味物质,其中浓香型白酒酿造腐乳检出物质79种,酱香型73种,清香型61种,老白干型79种,凤香型64种,米香型77种。挥发性风味物质组成差异表现为浓香型腐乳中酯类、酚类化合物种类最多;酱香型中醛类、喃类化合物种类最多;老白干型中酮类化合物种类最多;米香型腐乳中不仅醇类化合物种类最多,各类风味物质(除酚类)质量比最高,总质量比为135.18μg/g,清香型次之,总质量比为81.95μg/g,其他腐乳样本为6.59～16.60μg/g。研究结果为腐乳的研发和生产提供基础性数据,为高品质腐乳开发提供参考。     

Gamma irradiation,rheological and microbiological analysis of cosmetic products

In this study, we aimed to use gamma irradiation for decontamination of cosmetic product (gel) achieve the acceptable microbiological limits. Cosmetic product vials were irradiated (10–100 kGy) and physicochemical, microbiological and biological properties of these samples were evaluated in normal conditions. Decontamination dose for all samples was found to be about 10 kGy or below. A pseudoplastic feature was induced in the gel after irradiation suggesting a large applicability of gamma radiation to this purpose.     

Physicochemical aspects of the microbiology of edible table spreads

This article describes aspects of the microbiology of edible table spreads including milk fat spreads such as butter, fat spreads of the margarine type and mixed fat spreads with fat contents ranging from 80–95% to not less than 20% by weight of the product. The water-in-oil character of these products makes a major contribution to their microbiological stability especially after they have been exposed to the micro-organisms commonly encountered in a domestic environment. The microbiological stability of edible table spreads is also influenced by the concentration and physical nature of the continuous lipid phase with product stability increasing with greater proportions of crystallized fat. Edible table spreads containing higher proportions of water are more vulnerable to microbiological deterioration. This can be controlled by ensuring a dispersed aqueous phase in the product which consists of small discrete moisture droplets stabilized against coalescence. This stabilization can be achieved by the use of increased mono- and diglyceride concentrations and/or by increasing the viscosity of the dispersed moisture droplets through the use of stabilizers, thickeners and protein. The development of unacceptable levels of microbiological deterioration during domestic use is prevented by the addition of potassium sorbate to the aqueous phase. Additive free edible table spreads with acceptable shelf-life can be manufactured by controlling the distribution of dispersed moisture droplet size and nutrient composition .     

Volatiles from food irradiation

Abstract

Quality assurance of aseptic packaging should cover all factors from plant design up to the distribution of the products. To assure the sterility of the product there is a need for microbiological rapid methods besides the traditional microbiological methods. But before these methods can be applied, much investigation is needed. Furthermore, there is a need for nondestructive methods for on‐line detection of the package integrity and for controlling the quality of the product after preincubation.     

The role of microbiological testing in systems for assuring the safety of beef

The use of microbiological testing in systems for assuring the safety of beef was considered at a meeting arranged by the International Livestock Educational Foundation as part of the International Livestock Congress, TX, USA, during February, 2000. The 11 invited participants from industry and government research organizations concurred in concluding that microbiological testing is necessary for the implementation and maintenance of effective Hazard Analysis Critical Control Point (HACCP) systems, which are the only means of assuring the microbiological safety of beef; that microbiological testing for HACCP purposes must involve the enumeration of indicator organisms rather than the detection of pathogens; that the efficacy of process control should be assessed against performance criteria and food safety objectives that refer to the numbers of indicator organisms in product; that sampling procedures should allow indicator organisms to be enumerated at very low numbers; and that food safety objectives and microbiological criteria are better related to variables, rather than attributes sampling plans.     

Antimicrobial silver-montmorillonite nanoparticles to prolong the shelf life of fresh fruit salad

In this work, silver-montmorillonite (Ag-MMT) antimicrobial nanoparticles have been obtained by allowing silver ions from nitrate solutions to replace the Na⁺ of natural montmorillonite and then to be reduced by a thermal treatment. Ag-MMT were used as active antimicrobial compounds to improve the shelf life of fresh fruit salad. In order to assess their influence on product shelf life, sensorial and microbiological quality has been monitored during the storage. The microbiological quality was determined by monitoring the principal spoilage microorganisms (mesophilic and psychrotrophic bacteria, coliforms, lactic acid bacteria, yeasts and molds). Additionally, the evolution of sensorial quality was assessed by monitoring color, odor, firmness and product overall quality. The Ag-MMT nanoparticles seemed to be effective in inhibiting microbial growth, above all at the highest tested concentration. Consequently, the sensorial quality of samples stored in the active packaging appeared to be better preserved. Thus, experimental results showed that a significant shelf life prolongation of fresh fruit salad can be obtained by a straightforward new packaging system.     

天然防腐剂在鲜切水果和果汁保鲜中的研究进展

随着国民生活水平的提高,人们对低热量食品的需求不断增大,即食鲜切水果和果汁的消费也逐渐增加,它们的安全性越来越受到人们的重视。鲜切水果和果汁由于组织和形态被破坏极易受到病原微生物和腐败微生物的污染,如果加工或储存条件不当,极易造成微生物致病和腐败。微生物学、酶学、化学或物理学变化均能引起鲜切水果与未高温消毒果汁的质量损失。其中,微生物造成的损失非常重要,有两方面原因:一是微生物毒素或病原微生物对消费者的健康构成威胁,二是微生物腐败给消费者造成经济损失。使用防腐剂可以有效减少微生物污染增强安全性。天然防腐剂既能保证食品安全又能保持品质特征,近年来,将其用于鲜切水果与未高温消毒果汁以防止微生物腐败方面的研究备受关注。本文综述了来自动物、植物和微生物的天然防腐剂对鲜切水果和果汁中病原微生物及腐败微生物的抑菌作用。     

Impact of animal husbandry and slaughter technologies on microbial contamination of meat: Monitoring and control

The microbial flora transferred to carcasses during slaughter is a reflection of the care taken on the slaughter floor and of the types and numbers of microorganisms acquired by the animal on the farm or during the period of transportation to the slaughter house. These microogranisms may include those able to cause illness in the consumer, or microorganisms responsible for spoilage of the product. Considerable progress has been made in reducing contamination at slaughter and thereby extending the shelf-life of meat. In contrast, international statistics still clearly show that meat and meat products are responsible for a major proportion of all foodborne infections. This latter aspect is not determined by the overall number of microorganisms present but by the bacterial composition of the animal's gut flora at slaughter. Preventive quality assurance along the whole productions and processing line is therefore the only effective means of controlling the microbiological safety and quality of meat. This includes hazard analysis techniques to identify critical control points and procedures for monitoring the microbiological status of both animals and carcasses since most of the critical points cannot be totally controlled. At early stages in the production line, colonisation of meat animals with pathogens should be prevented. Subsequently, good slaughter practices will ensure carcasses of good overall microbiological quality. This paper deals with microbiological monitoring systems that can be used at different stages of production and processing to control the microbiological quality of poultry and pig meat.     

Review: Modified Atmosphere Packaging and its effects on the microbiological quality and safety of produce

Modified Atmosphere Packaging and related technologies are increasingly used to extend shelf-life of fresh produce. This paper reviews the effect of such technology on the spoilage microbiological flora and food-borne pathogens which may be present in produce and also on the organoleptic properties of the product.     

Influence of storing conditions of on quality and safety quality and safety of mushroom tins

The invention relates to the influence of period of time and storage conditions on microbiological, physical-and-chemical, sensory indices of mushrooms in brine salted (enzyme mushrooms). The invention establishes the fact that mushroom tin storage in a refrigerator at temperature between 0 degrees C and + 4 degrees C provides high quality and microbiological stability of the product during 2 years, storage in a warehouse with temperature between +10 degrees C and +18 degrees C - for 1 year.     

Commercialization conditions and practices influence the microbiological quality of mineral waters

The objective of the present study was to determine the microbiological quality of bottled mineral water marketed in commercial establishments and by street vendors and to evaluate the influence of the storage and maintenance conditions on the microbiological quality of the product. Ten samples from the same batches of five different brands of water were analyzed, for a total of 50 samples. Of the five brands analyzed, only one (brand A), when collected in a commercial establishment, complied with the legal Brazilian standards for mineral water with respect to the presence of total coliforms, fecal coliforms, and Pseudomonas aeruginosa. The remaining samples failed to comply with these microbiological standards for at least one of the parameters evaluated. The water samples obtained from street vendors were inferior in microbiological quality to samples from the same batch that were obtained from commercial establishments.