乔纳金苹果的应力松弛和蠕变特性与其品质相关性分析

为了简化苹果果实品质无损检测技术,探索苹果果肉力学特性与其品质的相关性,本文采用物性分析仪对乔纳金苹果货架期果肉进行蠕变和应力松弛试验,并对化学成分含量进行测定。结果表明:蠕变参数E_1、E_2、η_1、η_2与松弛参数E_1′、E_e、η等在货架期大体呈下降趋势;质构参数(TPA)果肉硬度、内聚性、弹性、咀嚼性等均与蠕变参数初始弹性系数E_1、延迟弹性系数E_2、黏性系数η_1和松弛参数平衡弹性模量E_e、松弛时间T_s、黏滞系数η之间呈显著正相关;可溶性固形物、原果胶分别与蠕变参数初始弹性系数E1、延迟弹性系数E_2、黏性系数η_1和松弛参数平衡弹性模量E_e、零时弹性模量E_0和黏滞系数η之间呈显著正相关;并通过逐步回归分析法构建一元线性回归模型。相关性和主成分分析表明,乔纳金苹果内在品质(可溶性固形物、原果胶)与蠕变、应力松弛黏弹性参数呈显著正相关,苹果果肉质地都具有黏弹性,兼具有黏性和弹性,且贡献率均等。     

氯化钠和氯化钙对玉米淀粉-瓜尔胶复配体系的影响

通过测定分析玉米淀粉-瓜尔胶复配体系在有无氯化钠和氯化钙存在条件下的糊化特性、动态与静态流变学特性,研究氯化钠和氯化钙对玉米淀粉-瓜尔胶复配体系的影响。结果表明,氯化钠和氯化钙的加入,提高了玉米淀粉-瓜尔胶复配体系的成糊温度,降低了崩解值和回升值,峰值黏度也略微下降;玉米淀粉-瓜尔胶复配体系的弹性模量G′值显著减小,黏性模量G″值的频率依赖性较大;氯化钠和氯化钙使玉米淀粉-瓜尔胶复配体系的假塑性增强,且氯化钙的作用大于氯化钠。     

亲水胶体对未漂洗革胡子鲶鱼鱼糜凝胶特性的影响

为比较亲水胶体对未漂洗的革胡子鲶鱼鱼糜凝胶特性的影响,分别将0.2%结冷胶(GNG)、0.2%卡拉胶(CGN)、0.2%可得然胶(CDG)及0.2%瓜尔豆胶(GRG)添加于未漂洗的革胡子鲶鱼鱼糜中,并测定凝胶特性、白度值、持水力、动态流变学性质和水分迁移变化规律等指标。结果表明,4种亲水胶体的添加均可不同程度地提高革胡子鲶鱼鱼糜凝胶的持水性、白度值、储能模量G′和损耗模量G″,GNG、CGN和CDG的添加有利于促进革胡子鲶鱼鱼糜凝胶中不易流动水向结合水方向迁移(P21增加),其中CDG组的持水性(95.77%)、破断力(500.80 g)、破断距离(8.46 mm)和凝胶强度(4335.69 g·mm)均为各处理中最大值,而添加GNG和GRG却会降低革胡子鲶鱼鱼糜的凝胶强度。综上所述,添加0.2%CDG可显著提高革胡子鲶鱼鱼糜的凝胶特性。     

表没食子儿茶素没食子酸酯对大豆分离蛋白凝胶的影响

为改善大豆分离蛋白(SPI)凝胶的强度,在SPI热诱导或酶诱导形成凝胶过程中添加表没食子儿茶素没食子酸酯(EGCG),制备EGCG/SPI凝胶体系.通过表面疏水性、自由巯基含量、内源荧光光谱和圆二色谱分析体系中SPI的结构改变,发现EGCG的添加提高了SPI的表面疏水性和自由巯基含量,蛋白质链展开,出现松弛和拉伸,分子柔性增加.圆二色谱结果表明无序结构(β-转角和无规卷曲)含量明显增加,β-折叠含量明显减少.进一步研究了热诱导和酶诱导下EGCG/SPI凝胶体系的形成作用力、凝胶强度、流变学特性、持水力及表面形貌的变化,结果表明,EGCG的添加增强了热凝胶中的氢键、疏水相互作用和二硫键,EGCG/SPI凝胶具有更高的持水力、凝胶强度和储存模量,以及更为紧密的三维网络结构.     

基因型和环境对面团流变学特性的影响研究

用揉混仪和质构仪研究了3个不同品质类型的冬小麦品种在8个不同的生长环境条件下的面团流变学特性,分析了基因型和环境对性状的影响及各性状间的相关性。结果表明：面团流变学特性受基因型（G）和环境（E）及其互作的共同作用,其中基因型方差均值＞环境方差均值＞G×E互作均值;从性状的表现看,基因型以济麦20表现最佳,环境以烟台点综合表现最好;相关分析表明,面团粘度性状与最大拉伸阻力、拉伸比、峰值时间、峰值面积和8min带宽呈显著负相关,而与延伸度呈显著正相关。最大拉伸阻力与峰值时间、峰值面积和8min带宽呈显著正相关。因此,进行品质评价时,可用质构仪测定的面团粘度特性对面团品质进行初步快速的评定。     

高脂血症金黄地鼠血液流变学研究

为了研究高脂血症金黄地鼠模型血液流变学特性的改变,研究采用14只叙利亚金黄地鼠随机分为2组,分别给予普通饲料及高脂饲料,10周后检测血浆甘油三酯、胆固醇、红细胞变形指数、取向指数、电泳率、全血粘度及血浆粘度,处死后,肝脏经油红O染色观测脂质沉积情况。结果显示高脂饲喂10周后,试验组动物体重、血浆甘油三酯、胆固醇、全血粘度及血浆粘度显著升高,红细胞的变形指数、取向指数、电泳率以及红细胞膜的流动性都显著降低,动物高脂血症引起显著的血液流变学特性变化。     

米粉凝胶强度与米粉品质指标的相关性研究

以市售米粉为研究对象,测定了其凝胶强度及质构参数,并分析了其凝胶强度与其蒸煮指标、质构指标以及感官评价之间的相关性。结果表明:米粉的凝胶强度与米粉的蒸煮损失、碘蓝值、熟断条率、硬度、弹性、咀嚼性以及感官指标中弹性、组织形态、糊汤性均存在显著相关性。在米粉的加工过程中,将米粉的凝胶强度控制在22.09~36.66 g·mm-2,大众接受程度会较高,在该范围内,米粉蒸煮损失<7%,熟断条率<2%,碘蓝值<0.300,弹性>0.89,米粉综合品质较好。因此,在米粉加工中,通过检测米粉的凝胶强度,并结合质构中硬度、黏性等指标的检测,即可反映米粉品质的好坏,无需再对米粉蒸煮损失、熟断条率等指标进行测定,有效地简化了米粉品质评价指标体系。     

波浪循环荷载作用下滨海软土水平向动力特性试验研究

为研究海上风电桩基在波浪荷载作用下,产生水平向循环荷载对桩基周围土体动力特性的影响,以唐山地区滨海软土为研究对象,通过室内动三轴试验,研究不同围压、动应力幅值和振动次数条件下对软土水平向动力特性的影响。结果表明：软土水平向动强度随围压增加而增加,随振动次数增加而减小;动应力幅值增大,破坏振次减小;水平向动应变εd随振动次数增加变大,且动应力幅值越大,增速越明显,变化规律遵循Monismith模型;动应力幅值改变时,软土水平向动模量变化明显,当围压减小,动弹性模量减小;曹妃甸软土水平向间具有明显的结构性,不同围压条件下,随动应力幅值增加动阻尼比均表现增大趋势。     

不同低温处理对小麦光合特性和产量性状的影响

为研究小麦在经受低温冻害后植株光合特性和产量性状变化规律,以‘周麦22’为研究对象,于拔节前期和拔节后期,分别设置-1℃、-3℃、-5℃、-7℃、-9℃温度梯度,低温处理4 h后,测定小麦光合特性和叶绿素SPAD值,并在收获后测量小麦植株性状变化。本研究结果表明,于拔节前期和后期,随温度的降低,小麦光合速率A,胞间CO2浓度Ci,叶片蒸腾速率E和气孔导度GH2O逐渐降低。但于拔节前期,-7℃处理较CK显著降低,且各低温梯度于7天后逐渐恢复正常。而于拔节后期,-5℃处理较CK显著降低,于各低温梯度于3天后逐渐恢复正常;在小麦拔节前期,温度低于-9℃时,SPAD值明显降低,而在拔节后期,温度低于-5℃时,SPAD开始显著降低;低温发生时间推迟,小蘖穗高降低,穗长缩短,粒数和千粒重则降低,而株高和单株成穗数增加。随温度的降低,小蘖穗高、株高降低和穗粒数显著降低。在发生低温冻害后,小麦生物产量和籽粒产量均显著降低。     

低温和差压式预冷对不同品种桃果实预冷性能的影响

为探讨不同品种桃果实的预冷性能及低温预冷和差压式预冷的差异性,分别以山东6个主栽品种的桃果实为试材,研究预冷期间不同品种桃果心温度的变化。结果表明:不同品种桃的预冷特性有一定的差异。低温预冷前期(预冷10 h以内),各品种桃果实的果心温度下降速率依次为:仓方早生美脆红珊瑚红不软、朝晖和早凤王,随着预冷时间的延长,差异性降低;与低温预冷相比,差压式预冷可显著缩短果实预冷所需的时间,以上各品种的果心温度由32℃下降到11℃所需的时间分别是低温预冷的1/3~4/5。由于不同品种桃果实的预冷时间有一定的差异,应根据品种的具体特点制定相应的预冷工艺。     

腌腊肉制品脂肪组织食用品质的成因分析

分析了传统腌腊猪肉制品皮下脂肪的组成及在加工过程中的变化,结果表明,低熔点三酰基甘油酯(POO,OOL和POL)的水解,消除了脂肪组织的油腻感,色泽变为透明,熟制后口感脆嫩、利口。三酰基甘油酯水解使游离脂肪酸含量增加,不饱和脂肪酸发生明显的氧化反应,形成许多具有挥发性的烃、醇、醛、酮、酸、酯、呋喃和吡嗪等类有机化合物,其中一些有机化合物对腌腊肉制品特有的风味具有重要贡献。低温和长时间的加工条件对脂肪水解和氧化程度的影响,是传统腌腊肉制品优良食用品质形成的关键。     

富含花色苷可吸米醋风味果冻配方及工艺研究

以黑米提取液为基料,以流变测试和感官评价为综合指标,在单因素试验基础上进行正交试验,优化获得富含花色苷可吸米醋风味果冻配方为魔芋胶-卡拉胶共混胶添加量0.04%(W/W,浓度比为1∶1),米醋添加量10%(W/W),柠檬酸钾添加量0.12%(W/W),白砂糖添加量10%(W/W)。最优条件下获得的可吸果冻制品色泽为淡黄色、组织形态均匀、米醋香味突出、酸甜适口、可吸性良好,且流变弹性模量值(G’)与市售产品非常接近,G’介于10.5~15.5 Pa,具备典型弱凝胶特征。研究结果可为稻米高值化利用及可吸醋基风味果冻开发提供参考。     

Grain quality and yield characteristics of D-genome disomic substitution lines in 'Langdon' (Triticum turgidum var. durum)

Sets of D-genome disomic substitution lines of ‘Langdon’ (Triticum turgidum var. durum) were used to study the effect of chromosome substitutions on grain yield and flour technological properties. In general, the substitution of any D-genome chromosome had a detrimental effect on grain yield and growth vigour (some lines were sterile). SDS-sedimentation, SE-HPLC and two-gram mixograph procedures were used to measure dough strength of the lines studied. Significant correlations were observed between protein concentration and grain yield and other quality parameters such as SDS-sedimentation value, the proportion of glutenin, dough mix time and peak resistance. Most of the quality characters were highly correlated with each other. Substitution of chromosomes 1D, 5D, 2D and 7D resulted in positive responses to SDS-sedimentation values, but only chromosome 1D had positive effects on the proportion of peak 1 (P₁%), measured by SE-HPLC. Besides the major influence of chromosome 1D on three major mixograph parameters (mixing time, peak resistance and resistance breakdown), chromosome 5D also exhibited significant effects on these mixing parameters. Principal-component analysis showed that the predominant effect on durum-wheat rheological properties was from chromosome 1D, whereas chromosome 5D had a major effect on grain hardness (50%) and increased the whiteness of the flour.     

Milling quality and protein properties of autumn-sown Chinese wheats evaluated through multi-location trials

Eight milling quality and protein properties of autumn-sown Chinese wheats were investigated using 59 cultivars and advanced lines grown in 14 locations in China from 1995 to 1998. Wide ranges of variability for all traits were observed across genotypes and locations. Genotype, location, year, and their interactions all significantly influenced most of the quality parameters. Kernel hardness, Zeleny sedimentation value, and mixograph development time were predominantly influenced by the effects of genotype. Genotype, location and genotype × location interaction were all important sources of variation for thousand kernel weight, test weight, protein content, and falling number, whereas genotype × location interaction had the largest effect on flour yield. Most of the genotypes were characterized by weak gluten strength with Zeleny sedimentation values less than 40 ml and mixograph development time shorter than 3 min. Eight groups of genotypes were recognized based on the average quality performance, grain hardness and gluten strength were the two parameters that determined the grouping, with contributions from protein content. Genotypes such as Zhongyou 16 and Annong 8903 displayed good milling quality, high grain hardness, protein content and strong gluten strength with high sedimentation value and long mixograph development time. Genotypes such as Lumai 15 and Yumai 18 were characterized by low grain hardness, protein content and weak gluten strength. Genotypes such as Yannong 15 and Chuanmai 24 were characterized by strong gluten strength with high sedimentation value and long mixograph development time, but low grain hardness and protein content lower than 12.3%. Genotypes such as Jingdong 6 and Xi’an 8 had weak gluten strength, but with high grain hardness and protein content higher than 12.2%. Five groups of locations were identified, and protein content and gluten strength were the two parameters that determined the grouping. Beijing, Shijiazhuang, Nanyang, Zhumadian and Nanjing produced wheats with medium to strong gluten strength and medium protein content, although there was still a large variation for most of the traits investigated between the locations. Wheat produced in Yantai was characterized by strong gluten strength, but with low protein content. Jinan, Anyang and Linfen locations produced wheats with medium to weak gluten strength and medium to high protein content. Wheats produced in Yangling, Zhenzhou, and Chengdu were characterized by weak gluten strength with medium to low protein content, whereas wheats produced in Xuzhou and Wuhan were characterized by weak gluten strength with low protein content. Industrial grain quality could be substantially improved through integrating knowledge of geographic genotype distribution with key location variables that affected end-use quality.     

Influence of high molecular weight glutenin subunit substitution on rheological behaviour and bread-baking quality of near-isogenic lines developed from Chinese wheats

Three near‐isogenic lines (NILs) of wheat involving Glu‐B1 and Glu‐D1 alleles were used to study the genetic contribution of high molecular weight glutenin subunits (HMW‐GS) to gluten strength. The HMW‐GS composition of each NILs was determined by SDS‐PAGE. No significant differences were found in grain protein contents among the NILs. Gluten strength and dough‐mixing properties were measured by the Farinograph, the Extensograph, and SDS‐sedimentation (SDS‐SE). Results indicated that line 2, containing the Glu‐1B 14 + 15 and Glu‐1D 5 + 10 combination of subunits, had higher values for flour quality, dough rheological parameters, and bread‐baking quality when compared with lines 8 and 13. Line 8, containing Glu‐1B 7 + 9 and Glu‐1D 5 + 10, was better than line 13 with the Glu‐1B 14 + 15 and Glu‐1D 10 combination. Some major parameters appeared significantly different. The presence of Glu‐1B 14 + 15 was associated with higher dough strength based on SDS‐SE volume and several rheological parameters when compared with Glu‐1B 7 + 9. Lines with subunit 10 at Glu‐D1 performed significantly worse than those with 5 + 10 in gluten index, SDS‐SE volume, Farinograph stability time, Extensograph area and bread‐baking quality.     

Theoretical Analysis and Experimental Test of Full-scale Bamboo Scrimber Flexural Components

The bending tests and theoretical analysis of five full-scale bamboo scrimber components were conducted and the flexural behavior of bamboo scrimber was researched in detail. Results show that the typical failure modes of bamboo scrimber flexural components are the bamboo fiber fracture at the bottom and interlaminar shear failure near the neutral axis. The sectional stiffness control the design for the bamboo scrimber flexural components, the ratio of PL/250 of the load corresponding to the deflection limit value of L/250 and ultimate load Pmax has good stability. The relationship model of bending tensile strength fm and elastic modulus E was established by regression, which shows that the sectional stiffness expressed by the elastic modulus could predict the bearing capacity well. The plane-section assumption is still valid. The bamboo calculation methods of scrimber flexural components were proposed considering the materials properties of bamboo scrimber based on wood structure design methods. The design value of bamboo bending strength, shear strength parallel to grain and the elastic modulus E were presented preliminarily.     

玉米茎秆弯曲性能与抗倒能力的研究

为探讨不同玉米品种茎秆抗倒伏相关的力学特点, 选用不同抗倒性品种登海3719、京科519和农大108, 设置3.00、5.25、7.50、9.25和12.00万 hm-2 5个密度, 分别于玉米抽雄前和蜡熟期取样, 用WDW3020型电子万能试验机对茎秆第3、5、7节间进行悬臂梁弯曲试验, 同时测定节间形态特征。结果表明, 随密度的增加, 茎秆基部节间直径变细、节间长度增长。品种间有一定的差异, 在3个品种中登海3719的平均直径和长度均低于其他2个品种; 品种间茎秆惯性矩也有较大差异。基部节间弹性模量、最大抗弯应力均随生育进程而增加, 但随群体密度的增加和节位的上升而逐渐降低, 登海3719在两个生育期均为最大, 且随密度增加的下降幅度较小。以京科519最低, 其对密度反应较敏感, 下降幅度大, 易发生倒伏。在玉米抽雄期, 基部节间平均弹性模量为40.0 MPa, 最大抗弯应力为2.8 MPa, 可能是茎秆抗折力学指标的下限。茎秆弹性模量与最大抗弯应力极显著相关, 茎秆直径与弹性模量和最大抗弯应力在抽雄前显著正相关, 而到蜡熟期相关不显著。它们与田间倒伏率呈极显著负相关。茎秆弯曲弹性模量反映茎秆的耐密能力, 茎秆最大抗弯应力反映品种茎秆的抗折能力, 而茎秆直径不能作为评价茎秆抗弯强弱的主要指标。玉米抽雄前期与蜡熟期茎秆抗弯性状的变化规律基本一致, 因此利用抽雄前茎秆基部弯曲力学性能鉴定与评价玉米茎秆抗倒、耐密性是可行的。     

4个品种扶芳藤茎叶解剖结构及其与抗旱性的关系

采用石蜡切片法制片，观察了4个扶芳藤品种茎、叶横切面的解剖结构，发现不同扶芳藤品种茎、叶的解剖结构相似，但其结构参数差异较大。运用方差分析和多重比较对其结构参数进行了分析，得出宽瓣扶芳藤的茎表皮角质层厚度、叶片上表皮角质层厚度、叶片厚度及叶片栅栏组织厚度等4个抗旱指标均最大，与另外3种品种间差异显著；金边扶芳藤的上述4个指标最小与另外3个品种间差异也显著。同时得出扶芳藤茎和叶片的表皮细胞外壁的角质层厚度、叶片厚度及叶片栅栏组织细胞的排列方式等结构特征与其抗旱性相关。4个扶芳藤品种的抗旱顺序从强到弱依次为宽瓣扶芳藤﹥红脉扶芳藤﹥紫红扶芳藤﹥金边扶芳藤。     

猪肉鸡肉复合肌原纤维蛋白凝胶特性

研究复合肌原纤维蛋白凝胶特性对研制高品质的猪肉鸡肉复合肉制品至关重要。通过单因素试验和二次多元回归设计试验研究谷氨酰胺转胺酶(TG-B)、猪肉鸡肉比、复合磷酸盐、pH值、加热温度和保温时间对肌原纤维蛋白凝胶强度的影响并对工艺进行优化。研究表明,TG-B酶用量、保温时间和保温温度对肌原纤维蛋白的影响显著;优化出凝胶强度与影响因素间关系的回归数学模型,当TG-B为3.4%,保温时间2.0 h,保温温度45.2℃时,复合肌原纤维蛋白凝胶强度最大为14.03 N.mm,验证试验结果为14.02 N.mm。