水分对涂抹型再制干酪的影响

水分是影响涂抹型再制干酪感官、质构和微观结构的重要因素.通过测定涂抹型再制干酪的pH、融化性、质构性质(TPA),并结合微观结构观察的分析方法,确定水分对涂抹型再制干酪品质的影响.结果表明,水分的增大使样品中pH增大,但对pH的影响不显著,融化性显著增强(P<0.05),对硬度、黏着性和涂抹功影响极显著(P<0.01).48%、54.3%和60%含水量时的微观结构明显不同,水分增大使酪蛋白网络结构由致密变得松散,同时脂肪球不断增大并聚集.     

猪胃蛋白酶制备新鲜干酪及其特性分析

以新鲜猪胃黏膜为原料,提取并初步纯化得到猪胃蛋白酶(PPe),分别从化学成分、产率、质构3 方面研究PPe 在新鲜干酪中的作用效果。结果表明：在化学成分上,PPe 优于微生物凝乳酶,尤其中剂量效果最好;在质构特性方面,PPe 制得的干酪比微生物凝乳酶及市售猪胃蛋白酶制得的干酪更接近皱胃酶(CR)制得的干酪,且高剂量PPe 制得的干酪硬度、弹性、内聚性、胶黏性和咀嚼性均与小牛皱胃酶制得的干酪无显著差异(P ＞ 0.05)。PPe 优于微生物凝乳酶及市售猪胃蛋白酶,可以作为小牛皱胃酶的替代物应用于新鲜干酪的生产。     

压榨工艺对干酪品质的影响

压榨是生产半硬质和硬质干酪的重要工艺。通过检测干酪的化学成分、质构特性、流变特性,研究了压榨过程中压榨时间、压强等参数对干酪品质特性的影响,并且结合共聚焦激光显微镜等手段分析了压榨工艺与干酪微观结构的关系。结果显示,随着压榨时间增加、压强增大,干酪样品的水分含量下降,脂肪和蛋白含量升高。随着压榨时间的延长、压强增大,用质构仪测得干酪的硬度和咀嚼性增大,弹性减小。流变仪测定结果显示干酪的弹性模量增加,熔化性减弱。干酪微观结构图显示,随着压榨时间的延长,蛋白网络更加致密有序;随着压榨压强的增大,脂肪球大量聚集,蛋白分子重列。研究结果揭示了压榨过程影响干酪品质的相关机理。     

热烫温度对哈罗米干酪理化性质的影响

探讨了不同的加热温度下对乳凝块理化性质以及成分含量的影响,以未经热烫的干酪凝块作为空白对照,分别测定了这五种干酪样品的pH值、水分质量分数、蛋白质质量分数、脂肪质量分数、油脂析出性、扫描电子显微镜、可榨乳清质量分数及质构特性。研究发现:随热烫温度升高,干酪的油脂析出性、硬度、脂肪含量等指标逐渐增大;热烫温度变化对样品的蛋白质、水分含量等指标影响不显著;扫描电镜观察发现随热烫温度升高,干酪结构致密性增加,此结果同干酪硬度随热烫温度变化相一致。综合评价80～90℃热烫工艺制得的哈罗米干酪质地较为坚硬,油脂易于析出,品质相对较好。     

高压微射流对姜汁黑豆酸奶流变学特性的影响

以生姜和黑豆为原料,利用瑞士乳杆菌（Lactobacillus helveticus）LH-B02、干酪乳杆菌（Lactobacillus casei）L casei-01、干酪乳杆菌NO1分别与嗜热链球菌ST3组合发酵制备姜汁黑豆酸奶样品,研究了高压微射处理对姜汁黑豆酸奶理化性质、流变学特性和微观结构的影响。结果表明,高压微射流均质能够明显提高酸奶的酸度和持水力,改善酸奶的流变学特性、黏弹性,并使剪切稀化特性明显增强,其中弹性模量、粘性模量及屈服应力t0明显提高,微观结构更加致密。其中以干酪乳杆菌NO1和嗜热链球菌ST3制备的姜汁黑豆酸奶总体可接受性最好（评分为8.54）,酸度为83.88°T、持水力为86.66%、屈服应力t0为8.94 Pa、表观黏度η50值为0.26 Pa·s。     

干酪物性的影响因素

干酪的物性包括熔化性,延展性,弹性,渗油性及硬度等.本文论述了乳的性质、干酪的制作过程、干酪的成分及干酪的后加工等影响干酪物性的因素.     

再制干酪乳化过程中理化、功能特性及微观结构的变化

以再制干酪为研究对象,探究再制干酪在不同乳化温度下（80℃和85℃）,从乳化开始到结束（5～30 min）,再制干酪功能特性（融化性、油脂析出性）、质构特性、流变学特性和微观结构的变化情况。结果表明,随着乳化时间延长,产品的融化性及油脂析出性呈下降趋势,乳化过程中85℃再制干酪的油脂析出性显著高于80℃再制干酪（P<0.05）。干酪的质构特性随着乳化时间的延长整体呈增大趋势,其中85℃干酪胶着性和咀嚼性显著增大（P<0.05）,85℃再制干酪的硬度、胶着性和咀嚼性均大于80℃。两种加工温度的干酪在相同乳化程度下干酪的储能模量（G’）均大于损耗模量（G”）,0.1～10 Hz内G’和G”都随频率的升高呈上升趋势。干酪的微观结构显示,乳化5～15 min时脂肪球数量大大减少且直径减小,分布更加均匀,蛋白质基质更加光滑,干酪结构更加致密;但乳化20～30 min时干酪的微观结构呈蜂窝状,即奶油化反应过度。因此,再制干酪加工过程中乳化时间短,奶油化反应不充分;再制干酪乳化时间过长会使质地发生不良变化。再制干酪乳化反应过程中,蛋白质-蛋白质和蛋白质-脂肪的相互作用增强,产品的功能特性...     

原料乳预酸化的pH对Mozzarella干酪功能特性的影响

采用直接酸化工艺,用柠檬酸将原料乳pH分别调节为6.37、6.09和5.73,研究了原料乳不同酸化的pH对Mozzarella干酪功能特性的影响。结果表明,随着原料乳预酸化pH的降低,干酪的TPA硬度显著降低(p<0.05),TPA粘性显著增加(p<0.05),对TPA弹性影响不显著,干酪的融化性和拉伸性显著增强(p<0.05)。     

乳酸菌胞外多糖的应用

主要归纳和总结了乳酸菌胞外多糖作为食品添加剂在食品中的应用,以及产胞外多糖的乳酸菌作为″粘性″发酵剂在酸奶和干酪生产中的应用。     

热变性乳清蛋白-黄油乳液凝胶对减钠再制干酪品质的影响

再制干酪中较高的钠含量被越来越多的消费者所关注。再制干酪中钠主要来自于原制干酪及乳化盐。乳化盐主要作用是促进脂肪在体系中均匀分布,使蛋白质、脂肪等形成均匀的网络体系。本研究利用热变性乳清蛋白对黄油进行预乳化处理,形成乳清蛋白-黄油乳液凝胶(WPI-EG)后,将其用于干酪加工,检测减钠再制干酪的油析性、融化性、质构及微观结构等,评价热变性乳清蛋白预乳化工艺对减钠再制干酪品质的影响。结果表明:预乳化工艺中WPI-EG的形成能够有效促进再制干酪中脂肪均匀分布,形成均匀的结构和质地。预乳化工艺提高了再制干酪的硬度、胶着度和咀嚼度,降低了干酪的油析性。降低30%含钠乳化盐的预乳化再制干酪(30%EC)与未预乳化的干酪(NEC)相比,钠含量降低52.9 mg/100 g,硬度增加27.1%,油析性降低0.53 cm。微观结构显示:30%EC样品脂肪分布及蛋白网络结构更加均匀、致密。本研究结果说明预乳化工艺能够有效降低再制干酪中含钠乳化盐添加量,改善干酪品质。     

PC钢丝生产中断丝分析与预防

对PC钢丝生产中断丝试样进行化学成分检验和断口金相检验 ,结果显示断口试样中Cr成分比正常盘条低 2 5 % ,并存在网状铁素体。分析认为 ,网状铁素体是造成钢丝“杯锥状”断口的原因 ,盘条出现屈氏体组织是导致平直断裂的原因 ,化学成分偏析是导致不规则型断口的原因 ,并对产生不规则断口的影响因素进行讨论 ,提出了生产中避免断丝的措施     

The use of computer-assisted image analysis in the evaluation of the effect of management systems on changes in the color,chemical composition and texture of m. longissimus dorsi in pigs

The effect of management systems on selected physical properties and chemical composition of m. longissimus dorsi was studied in pigs. Muscle texture parameters were determined by computer-assisted image analysis, and the color of muscle samples was evaluated using a spectrophotometer. Highly significant correlations were observed between chemical composition and selected texture variables in the analyzed images. Chemical composition was not correlated with color or spectral distribution. Subject to the applied classification methods and groups of variables included in the classification model, the experimental groups were identified correctly in 35–95%. No significant differences in the chemical composition of m. longissimus dorsi were observed between experimental groups. Significant differences were noted in color lightness (L*) and redness (a*).     

Effects of hydrocolloids on chemical properties and cooking quality of gluten‐free spaghetti

The effects of different hydrocolloids on chemical composition and cooking quality of spaghetti based on maize and oat flours were investigated. Rheological and texture properties of the gluten‐free dough were also assessed. Amount of 2% of gellan gum, carboxymethylcellulose, pectin, agar, egg protein powder, tapioca starch, guar seed flour and chitosan were separately added to the formulation. The samples enriched with hydrocolloids generally showed a different rheological behaviour compared with the control samples. As regards chemical composition, spaghetti with chitosan showed a value of insoluble dietary fibres (8.0%) higher than the control ones (3.9%). Moreover, results highlighted that most hydrocolloids improved cooking quality and texture properties of spaghetti (adhesiveness, cooking loss, hardness), thus supporting their application in gluten‐free pasta.     

Classification of Kashar Cheeses Based on Their Chemical,Color and Instrumental Textural Characteristics Using Principal Component and Hierarchical Cluster Analysis

Principal component analysis and hierarchical cluster analysis were applied to investigate physicochemical and instrumental textural properties of fresh kashar cheese. Four different principal components sufficiently explained the variability in the cheese samples. In addition, hierarchical cluster analysis was performed to group the kashar cheese samples regarding physicochemical and instrumental textural properties. Instrumental textural properties indicated greater variability than chemical composition of cheese samples. Principal component analysis revealed that color parameters were positively correlated with textural and chemical parameters. The results of this study revealed that other parameters rather than chemical composition would be effective on the instrumental textural properties. It was proved that principal component analysis was a very effective statistical tool to determine quality of cheese samples. According to the principal component analysis and hierarchical cluster analysis results, the attributes defining the kashar cheese samples were determined to be primarily the texture profile analysis parameters.     

ALKALI-NEUTRALIZATION PROCESS MAINTAINS THE FIRMNESS AND SENSORY QUALITY OF CANNED SWEETPOTATO PIECES1

Jewel cultivar SP stored 1, 5, and 10 months after harvest were peeled, cut into pieces, treated, and canned in 15 and 30 deg Brix syrups. Samples were evaluated for degree of disintegration (wholeness), firmness (shear force), chemical composition, and sensory acceptance. Untreated samples (controls) disintegrated as storage time prior to processing increased, while treated samples remained intact; firmness and sensory texture scores declined with increasing storage time. Treated samples were significantly firmer than controls throughout the study, and, although shear force declined over time, sensory panelists did not detect any texture change. Overall sensory acceptance at 10 months was greatest for phosphate-treated samples in 30 deg Brix syrup. Thus, the alkali-neutralization process retains firmness, wholeness, and sensory quality of SP canned after long-term storage. This process will permit commercial processing of SP roots stored for up to 10 months.     

Some Quality Parameters of Dry Fermented Sausages (Čajna kobasica)

The aim of this study was to evaluate some quality parameters of dry fermented sausage (Čajna kobasica) from different producers from the market in Vojvodina. The investigated parameters were chemical composition and sensory properties of external appearance and/or condition of the packaging, appearance and composition of cut surface, color and stability of color, odour and taste and texture and/ or juiciness. The results showed that the chemical parameters were very variable but in an agreement with Serbian legislation. Sensory scores were different among different producers. Overall sensory quality of tested samples ranged from 3.37 to 4.34.     

湖北随州叶家山西周曾国墓地出土玉器的玉质研究

湖北随州叶家山西周曾国墓位于湖北省随州市东北部,于2010年底被发现,出土玉石器三百余件。本文研究对象是出自M1、M3、M27、M28、M65号墓的29件出土玉器,采用宝玉石学和岩石学的研究思路和无损(微损)测试方法对该批样品进行了研究。肉眼观察结合基础宝石学测试表明,29件颜色和受沁程度不同的出土玉器样品中,27件为软玉,另2件需通过大型仪器测试鉴别。大型仪器测试以红外吸收光谱和激光拉曼光谱测试为主,对29件出土玉器样品进行玉器材质的定性分析,27件出土玉器样品显示了典型的透闪石红外吸收光谱和拉曼光谱,另2件中样品M28-63-FJ-1显示了典型的蛇纹石红外吸收光谱和拉曼光谱及样品M111∶48-50在262、405、699cm-1处显示了典型的白云母拉曼光谱。激光剥蚀电感耦合等离子体质谱仪(LA-ICP-MS)对6件出土软玉样品的化学成分测试结果显示,其主要化学成分为CaO、MgO、SiO2,其质量分数分别在13.55%~14.30%,23.78%~26.02%和56.98%~58.94%之间,属于软玉的理论范围。根据微量元素中Fe的质量分数计算6件软玉样品的主要矿物种类,其中样品M65∶WH-BLACK的R*值为0.834,主要矿物组成为阳起石,其余5件样品R*值均大于0.9,为透闪石质软玉,6件样品皆产于白云石化大理岩型软玉矿床。扫描电子显微镜观察显示受沁部位的侵蚀坑以及软玉的纤维交织状结构。大型仪器可以相对准确地分析玉器的材质、化学成分和结构特征,弥补了肉眼观察和基础宝石学测试的局限性。     

基于相关性分析和主成分分析的米豆腐品质评价

以10种市售米豆腐为研究对象,对其化学成分、质构和色值指标进行分析。结合感官评定,利用相关性分析、主成分分析和聚类分析的方法,旨在分析指标间的相关性,筛选评价米豆腐品质特征的指标。结果表明,化学成分与米豆腐的质构和色值间有显著的相关性,进而决定米豆腐的质地、口感以及外观品质。主成分分析确定水分、淀粉、蛋白质、pH、粘附性、咀嚼性和L*值这7个品质指标代表原有的16项指标,其主成分的累积贡献率达84.94%,说明它们能够反映大部分所需要的关于米豆腐品质的信息。同时,结合聚类分析,将10种米豆腐样品分为鲜食型和烹饪型两大类。本文的研究结果为米豆腐评价方法和指标的建立提供理论基础。     

不同硬度奶酪的质构及流变特性比较

针对3 种不同奶酪样品(硬质、半硬质、软质)对其进行成分分析、质构特征参数(应力松弛、破断)测定、质地剖面分析(TPA)、感官评定及动态流变特性实验。结果表明：奶酪样品硬度的不同对其质构特征和动态流变参数有明显影响;硬质奶酪具有弹力大的特点;黏聚性小、破断强度大,软质奶酪具有弹力小、黏聚性大、破断强度小的特点;在整个频率扫描范围内,随着硬度的下降,样品的贮藏模量(G′)、损失模量(G″)、动力学黏度( η′)都呈下降趋势。     

Changes in the texture,physicochemical properties and volatile compound profiles of fresh Kashar cheese (<90 days) during ripening

In this study, four different fresh Kashar cheese samples were ripened for 90 days. The physicochemical properties, texture attributes, fatty acid composition and volatile compound profiles of the samples were measured every 30 days of ripening. The texture properties of the cheese samples were significantly affected by the duration of the ripening period. The results of this study highlighted that texture parameters as a function of ripening period should be considered for both fresh and aged Kashar cheeses to determine the ripening period as they are very important for consumer acceptability and consumption of the end product.