压缩比对火腿肠制品质构特性的影响

为在测定火腿肠质构特性时选择合理压缩比,研究30%～80% 范围压缩比对不同等级火腿肠质构特性的影响。结果表明：脆性指标检出与否是确定压缩比的重要参考依据;在火腿肠制品的凝胶系统达到一定强度时,采用的压缩比趋于一致。     

Determination of Nitrite and Nitrate in Brazilian Meats Using High Shear Homogenization

Nitrate and nitrite are usually added to processed meat products to protect against the growth of microorganisms. Two sample preparation methodologies using either manual grinding (with a mortar and pestle) or mechanical high shear homogenization were investigated and compared. The results showed that high shear homogenization was the most suitable for the extraction of nitrite and nitrate from ham, salami, and bacon samples, achieving high extraction recoveries (>98%) together with low relative standard deviations (RSDs) for the samples analyzed. Analyses were performed using capillary electrophoresis. A running buffer consisting of 60 mmol L⁻¹ tetraborate and 0.2 mmol L⁻¹ cetyltrimethylammonium bromide enabled separation of the analytes in <5 min. In validation experiments, good repeatability was obtained for both migration times (<0.8% RSD) and peak areas (<1.1% RSD). Analytical curves for nitrite and nitrate were linear (r > 0.998) in the 0.2- to 2.5-mg L⁻¹ and 0.5- to 5-mg L⁻¹ concentration ranges, respectively. The limits of detection were 0.15 mg L⁻¹ for nitrite and 0.17 mg L⁻¹ for nitrate. The method developed was applied to the analysis of different kinds of meats (sausage, ham, salami, bacon, and others) produced in Brazil. The ranges of concentration found were 17.3–46.4 mg kg⁻¹ (nitrite) and 69.9–198.1 mg kg⁻¹ (nitrate). The contents of nitrate and nitrite in the samples were below the Brazilian legislation limit values (150 and 300 mg kg⁻¹ for nitrite and nitrate, respectively).     

Textural Characterization of Cheeses Using Vane Rheometry and Torsion Analysis

ABSTRACT Vane rheometry was applied to textural characterization of cheeses and compared with torsion analysis. A Haake VT 550 viscotester was used for both vane and torsion tests at strain rates of 0.003 to 0.524 s^-1. Angular deformation and shear stress in the vane test increased with increasing low strain rate and was rate independent at higher rates. This shear rate dependency of stress and deformation varied with cheese types. Shear stresses from the vane method were lower than torsion shear stresses. Similar texture maps of cheeses were generated by plotting stress and strain or angular deformation values from the 2 testing methods. The findings indicate the vane technique can be used for rapid textural characterization of cheeses.     

夹层结构纸板压缩剪切性能试验研究

采用改进的组合式压缩剪切夹具,测试不同厚度的蜂窝纸板和高强瓦楞复合纸板横、纵向的剪切载荷一位移数据并绘制了相应曲线以及对应的抗剪切强度柱状图。测试结果表明：对于夹层结构纸板纵向样品的抗剪切能力大于横向样品;在用纸定量和质量相同时,相同方向的蜂窝和高强瓦楞复合纸板的抗剪切能力随厚度的增加而降低,相同厚度和方向蜂窝纸板的抗剪切能力大于高强瓦楞复合纸板,蜂窝纸板的抗剪切性能比高强瓦楞复合纸板更好。研究结果对于夹层结构纸板的进一步应用提供了压缩剪切方面的依据。     

基于消除空间冗余和图像修复的图像压缩技术

本文介绍了一种基于图像修复方法的图像压缩算法.首先对能够被精确覆盖的图像区域进行定位;然后将这些区域的信息消除以减少数据量;除了用于恢复被消除区域必要细节的数据外,对其余的数据进行编码以产生输出数据.在解码器中,使用从编码器中提取的信息可以重新获得被消除的图像区域.该修复技术利用偏微分方程(PDE)进行图像信息收集,其目的是达到图像压缩标准中的较高质量.本文还针对各种图像开展该算法的研究.采用这种算法,在图像质量可接受的条件下,压缩比可高达1:40.实验结果表明,与JPEG压缩方法相比,该算法在高压缩比下图像质量明显提高.     

Prediction of Sensory Profile of Mango Using Textural Attributes During Ripening

Mango is an important commercial fruit and is marketed based on their colour, firmness and taste. These sensory parameters vary with individual mango and person involved in testing. There is little or no information available on the instrumental estimation of these sensory attributes. The present study, therefore, was conducted to correlate sensory and instrumental textural attributes to explore the possibility of predicting them for seven major cultivars of mango influenced by harvesting dates and ripening period (10 days). In general, the textural property of peel, pulp and fruit decreased while sensory attributes increased during fruit ripening. Sensory qualities like taste, flavour and overall acceptability were significantly affected by harvesting date, cultivar and ripening period. Harvesting time and cultivars, however, did not influence the fruit appearance. Among textural attributes, peel firmness was closely associated with all the sensory parameters indicating that textural parameters could be useful to predict sensory profile of mango cultivars during their ripening. Cultivar-specific variations were observed while evaluating various equations (linear/polynomial/exponential/logarithmic/power) for correlating their textural and sensory attributes. Polynomial equation was found to be the best fit (highest coefficient of determination, R ²) for prediction of sensory quality using textural properties of majority of mango cultivars. All cultivars under study except Alphonso collected from Maharashtra showed R ² value above 0.911 which indicated potentiality of the fitted equations for the prediction of sensory attributes using textural characteristics of mango.     

Mechanical Properties of Melon Measured by Compression,Shear, and Cutting Modes

Mechanical properties of three common varieties of melon were measured. These are toughness, rupture force, shear strength, maximum shearing force, and cutting force. The role of peel (%) on each property was also calculated as the relative contribution of peel to unpeeled produce. The shear strength of peel was statistically found similar (p > 0.05) for all varieties. The same result was also revealed for unpeeled produce. Using rupture force was not recommended for peeling watermelon, because of close values of this property for its peel and unpeeled case. The required energy for peeling all three varieties of melon was determined to be 500 N mm. Peeling melons using cutter tools could not be recommended.     

Peck Substances of Sweet Cherries and Their Alteration during SO2 Brining

SUMMARY— During ripening the proportion of protopectin in the cherries decreased as did the average intrinsic viscosity of the pectic material. Brining of the cherries resulted in a further decrease in the intrinsic viscosity and a conversion of protopectin and pectinic acid to the pectic acid form. The texture of the brined cherries softened with increasing maturity of the starting material. On prolonged storage in SO² brine the texture of the cherries softened, and the intrinsic viscosity of the pectic materials decreased. The use of brines with pH levels above and below pH 3.1-3.5 caused a decrease in the intrinsic viscosity. A slight increase in pectic breakdown was seen when the SO² was raised to the 2% level. The overall effect of brining on the pectic materials of the cherries was to cause extensive de-esterification and a decrease in the viscosity average molecular weight.     

Identification of Key Textural Attributes of Fluid and Semi-Solid Foods Using Regression Analysis

Regression analysis was used to identify key attributes from 15 textural terms generated by a panel for 27 fluid and semi-solid commercial foods. A search using single independent variables showed that “thick” gave the best average R² with a value of 0.548; a search with two independent variables showed that “thick” and “soft” gave the best average R² of 0.748; a search with three attributes showed that “slippery”, “thick,” and “soft” gave the highest R² values of 0.803. The final equations provided a set of regression parameters which can be used to predict twelve textural attributes from scores obtained for “thick”, “soft”, and “slippery”.     

基于果核壳的元素和稳定同位素比值测定及车厘子产地分析

该研究应用电感耦合等离子体质谱仪（ICP-MS）,元素分析-稳定同位素比质谱仪（EA-IRMS）对车厘子果核壳中37种元素含量和氢、氧、碳、氮稳定同位素比值进行测定,并应用于车厘子产地分析中。车厘子去果肉和果仁后,将果核壳烘干并研磨成粉末,微波消解后通过ICP-MS对元素含量进行测定,果核壳粉末通过元素分析-稳定同位素比质谱仪对氢、氧、碳、氮稳定同位素比值（δ2H、δ18O、δ13C和δ15N）进行测定。应用上述方法对澳大利亚、美国、新西兰、智利和中国的车厘子样品进行元素含量和稳定同位素比值的测定,并对检测结果进行方差分析、主成分分析、聚类分析和判别分析,对车厘子产地的归属进行研究。研究结果表明基于车厘子果核壳的元素含量和稳定同位素比值综合分析,可以对车厘子产地进行区分,其中Mn、Co、Rb、Sr、Ba和δ2H组合指标整体交叉检验判别准确率92.1%。     

Anthocyanin and Polyphenolic Composition of Fresh and Processed Cherries

ABSTRACT: The distribution of anthocyanin pigments and polyphenolics in 1 sour cherry ( Prunus cerasus ) and 3 sweet cherry ( Prunus avium ) cultivars was determined by high-performance liquid chromatography with diode array detection. Changes during frozen storage, canning, and brining were also monitored. Sweet cherry cultivars differed qualitatively with respect to the minor anthocyanins. Hydroxycinnamates are the major class of polyphenolics in sweet cherries, whereas flavanols are in the majority in Montmorency cherries. Hydroxycinnamates were greatly affected by processing and storage, whereas flavonol glycosides were quite stable. Half of the anthocyanins and polyphenolics were transferred to the syrup with canning, and nearly all were transferred to brine during brining.     

苯乳酸-海藻酸钠涂膜保鲜剂的制备及其在甜樱桃保鲜中的应用

利用苯乳酸的抑菌能力和海藻酸钠的成膜性制备苯乳酸-海藻酸钠涂膜保鲜剂,并应用该保鲜剂对甜樱桃 进行涂膜保鲜。通过测试保鲜剂成膜的性能,确定保鲜剂中海藻酸钠的适宜添加量;通过测定甜樱桃生理指标和品 质指标的变化,研究保鲜剂对甜樱桃的冷藏保鲜效果。结果表明：在6 g/L苯乳酸、5 g/L甘油、5 g/L黄原胶存在的 情况下,海藻酸钠添加量为12 g/L时制备的保鲜剂有较好的成膜性能。应用该保鲜剂保鲜甜樱桃,能较好地抑制甜 樱桃的腐烂,减少水分散失,降低呼吸强度,保持贮藏甜樱桃的色泽和硬度,延缓可溶性固形物和可滴定酸质量分 数的下降,从而有利于降低甜樱桃代谢强度,保持果实品质,延长甜樱桃的保鲜期。     

Storage and Cultivar Effects on Shear Compression Values and Esterified Cell Wall Phenolics in Carrots

ABSTRACT: Phenolics esterified to cell walls in carrots were found to consist primarily of p-hydroxybenzoic acid with minor contributions from ferulic and vanillic acids and vanillin. These compounds could be indexed by standardized measurement of absorbance at 254 nm. As indexed, esterified cell wall phenolics varied widely between carrot cultivars and increased with carrot storage. These increases were not correlated with increased carrot toughness as determined by measurements in a shear compression cell. Carrot texture was unaffected by the levels of esterified cell wall phenolics present in the tissue.     

玉米淀粉/酪蛋白复合物凝胶的质构特性和结构研究

系统考察了不同比例的玉米淀粉/酪蛋白的凝胶质构特性,并利用差示扫描量热和激光拉曼光谱技术对玉米淀粉与酪蛋白复合物的热力学性质和分子结构的变化进行了研究.结果表明,玉米淀粉/酪蛋白凝胶的硬度、黏附性、胶黏性、咀嚼性与玉米淀粉和酪蛋白之间的比例密切相关,在酪蛋白含量占固形物比例为40.0％～50％时其凝胶质构性能发生较大变...     

响应面优化鱿鱼须酶法脱皮工艺及其质构特性

采用不同蛋白酶进行鱿鱼须脱皮实验,以白度值和原料保留率为指标,筛选出最适蛋白酶。在单因素试验基础上,采用Box-Behnken试验设计优化秘鲁鱿鱼须酶法脱皮工艺参数,并通过挥发性盐基氮（total volatile basicnitrogen,TVB-N）含量、质构与显微组织分析样品的新鲜度及质构特性。结果表明,回归模型能较好反映因素水平与响应值的关系,并确定最适酶法脱皮工艺为胰酶添加量0.25%、料液比17∶20（g/mL）、酶解时间20 min,在此条件下,样品的白度值为63.95±0.31,原料保留率为（81.22±0.28）%,TVB-N含量为（27.60±0.34） mg/100 g,且质构特性与肌纤维组织均无显著变化。脱皮后的秘鲁鱿鱼须TVB-N含量符合GB 2733-2005《鲜、冻动物性水产品卫生标准》规定,色泽鲜亮、肉质有弹性、原料保留率高,该工艺适合生产实际需求。     

QuEChERS-液相色谱串联质谱法快速检测猕猴桃中的氯吡脲及其代谢产物

氯吡脲是一种猕猴桃生长过程中常用的植物生长调剂,主要作用是增加猕猴桃果实的尺寸和重量。本研究通过化学合成得到氯吡脲代谢产物标准品,利用高效液相色谱串联质谱(LC-MS/MS)建立了猕猴桃中氯吡脲及其4种代谢产物(4-羟基-氯吡脲、3-羟基-氯吡脲、氯吡脲-4-O-β-D-基葡萄糖苷和氯吡脲-3-O-β-D-基葡萄糖苷)同时检测的定性定量方法。样品前处理利用乙腈作为萃取溶剂提取氯吡脲残留,通过PSA添加量的优化改进了QuEChERS样品前处理方法,5种化合物在LC-MS/MS正离子多反应监测模式下进行质谱分析。结果显示:样品前处理过程中PSA的添加量为400mg/15mL,氯吡脲及其4种代谢产物在一定浓度范围内线性关系良好(r2≥0.995),相对标准偏差(RSD)低于7.1%,重复性好,检出限为1~3μg/L,定量限为5~10μg/L,平均添加回收率87%~108%。该方法快速、准确、灵敏及稳定,能满足果蔬中氯吡脲及其代谢产物残留的同时检测。     

樱桃生理变化及保鲜机理研究进展

樱桃富含多种营养物质及活性成分,但采后极易腐败变质,造成极大经济损失。该文查阅国内外数据库相关文献,对采后樱桃的生理变化、保鲜技术及机理进行总结,以期为樱桃采后贮藏保鲜技术的进一步发展提供理论依据。     

改性麦饭石对水中氮磷的去除

分别采用加热、羟基铝柱撑和稀土镧对天然麦饭石进行改性,以模拟自然富营养水为处理对象进行改性麦饭石脱氮除磷实验研究。考察了投加量、p H值,以及反应时间等因素对改性麦饭石吸附性能的影响。并通过BET、SEM和XRD对改性前后麦饭石结构进行了研究,探讨了麦饭石的改性机理。结果表明,不同改性方法都能使麦饭石去除氮磷能力显著提高,对氨氮和总磷吸附效果最好的是稀土改性麦饭石,其次为柱撑改性麦饭石和热改性麦饭石。p H值为8,麦饭石投加量为15 g/L,反应时间为60 min条件下,稀土改性麦饭石的氨氮和总磷去除率最高,分别达到89%和75%左右。