基于香蕉、粉蕉成熟过程中硬度变化建立成熟度随机森林模型

【目的】研究香蕉和粉蕉成熟过程中果实柄部、中部和端部的硬度变化,并据此建立随机森林模型预测其成熟度。【方法】通过GY-4型果实硬度计分别测量香蕉和粉蕉成熟过程中果实柄部、中部、端部3个部位的硬度,并用相关性分析研究果实硬度与其他相关成熟指标之间的关系。使用相似性分析(ANOSIM)分别对香蕉与粉蕉成熟过程中果实3个部位的硬度进行分级后,通过随机森林算法(Random Forest)构建模型预测其成熟度,再比较果实各部位硬度对模型的重要性。【结果】香蕉和粉蕉成熟过程中果实硬度变化趋势相似,果实3个部位的硬度变化不一致。利用相关性分析发现香蕉与各种酶类活性和乙烯释放量呈显著负相关关系。香蕉和粉蕉成熟度随机森林模型的错误率分别为4.94%和0%,说明此模型能准确预测香蕉与粉蕉的成熟度,且香蕉果实中部与粉蕉果实柄部的硬度对模型的影响最大。【结论】利用随机森林模型,香蕉和粉蕉成熟过程中果实硬度能准确预测其成熟度,且果实3个部位的硬度变化不一致,根据果实不同部位的成熟度差异可提高利用率,香蕉果实中部与粉蕉果实柄部的硬度更能反映自身的成熟度,为鲜食蕉成熟度量化与快速监测分级提供参考,促进食品加工工业的发展。     

猕猴桃果实软化过程中细胞壁多糖物质含量与果胶降解相关酶活性变化

为研究不同贮藏温度下不同品种猕猴桃果实软化过程中细胞壁多糖物质降解特性,以及相关果胶降解酶对猕猴桃果实软化进程的影响,测定25℃和4℃贮藏过程中徐香、金丽、晚绿猕猴桃果实的硬度、细胞壁多糖物质含量和果胶降解相关酶活性,并对其进行相关性分析。结果表明,3个品种猕猴桃果实软化过程中半纤维素、纤维素和共价型果胶(covalent soluble pectin, CSP)含量不断降低,水溶性果胶(water soluble pectin, WSP)含量不断增加,而离子结合型果胶(ionic soluble pectin, ISP)含量相对稳定。晚绿猕猴桃各细胞壁多糖组分含量变化速度最快,金丽次之,徐香最慢。4℃贮藏延缓了猕猴桃果实细胞壁多糖物质的降解。相关性分析结果表明,3个品种猕猴桃果实硬度与WSP含量之间均呈显著(P<0.05)负相关,与CSP、半纤维素、纤维素含量之间呈显著正相关。果胶降解酶活性测定结果显示,25℃贮藏前期,晚绿猕猴桃内切多聚半乳糖醛酸酶(endo-polygalacturonase, PG)和β-半乳糖苷酶(β-galactosidase,β-Gal)活性显著高于...     

番茄果实硬度与多个性状间相关分析及通径分析

番茄果实硬度是番茄重要商品性状之一。为选育硬度较高番茄品种,文章分析硬度差异较大的两种番茄杂交后代F2,测量F2代380株番茄果实横径、纵径、果形指数、心室数、果肉厚等形态性状及可溶性固形物、果实硬度、果肉硬度、黏度、单果重等品质性状,对番茄硬度与其他品质及形态性状作相关分析及通径分析。结果表明,果肉硬度、可溶性固形物、果形指数、果肉厚、纵径与果实硬度呈正相关,心室数、黏度、横径、单果重与果实硬度呈负相关,且表型相关和遗传相关基本一致,其中果肉硬度、可溶性固形物对番茄果实硬度贡献呈极显著正效应,心室数、黏度对番茄果实贡献呈极显著负效应。     

Plant oil emulsion modifies internal atmosphere, delays fruit ripening, and inhibits internal browning in Chinese pears

'Laiyang Chili’ and ‘Ya Li’ (Pyrus bertschneideri Reld) pears were treated with 3, 6, and 9% emulsions of commercial or refined (reduced -tocopherol levels) plant (soybean, corn, peanut, linseed, and cottonseed) oils at harvest an stored at 0°C for 6 months. Effects of oil treatments on ethylene production, respiration, fruit firmness, fruit color, soluble solid content (SSC), titratable acids (TA), internal browning (IB), and internal CO₂, O₂, and ethanol were studied. At the same concentration, oil treatments induced similar responses regardless of their sources or their -tocopherol concentrations. In both cultivars, ethylene production and respiration in fruit treated with 9% oils were lower in early storage and higher in late storage than that in the controls. Oils at 6% reduced IB, at 9% inhibited IB completely, and at 3% was not effective after 6 months at 0°C and 7 days at 20°C. Plant oil treatment maintained fruit color, firmness, SSC, and TA in a concentration-dependent manner during storage. In the first 4 months storage, 9% corn oil-treated fruit contained similar partial pressure of CO₂ and O₂ as the controls. After 5 months storage, oil-treated fruit contained higher partial pressure of CO₂ and lower levels of O₂ than the controls. When held at 20°C for 7 days, changes of internal CO₂ and O₂ were slower but partial pressure of CO₂ were higher, and O₂ were lower, in 9% corn oil-treated fruit than in the controls. Internal ethanol was not affected by oil treatment compared with control, either during storage or 7 days at 20°C. No off-flavor was detected in either oil-treated and control fruit by sensory evaluation.     

叶面喷施NaCl对加工番茄果实耐挤压性和品质的影响

以加工番茄品种里格尔87-5和石红12为试材,研究了在果实发育期叶面喷施不同质量浓度NaCl对果实耐挤压性和品质的影响。结果表明,在适宜质量浓度范围内,叶面喷施NaCl可以提高加工番茄果实硬度、耐压力和产量,改善果实品质,但两个品种对NaCl质量浓度的反应有一定差异。对品种里格尔87-5,3.0 g/L NaCl处理使产量和果实硬度极显著提高,果实耐压力、可溶性总糖、还原糖和Vc含量增加;6.0 g/L NaCl处理可显著增加还原糖和可溶性总糖含量,对果实硬度、耐压力、Vc含量和产量的影响不大;9.0 g/L NaCl处理使果实硬度极显著降低,并对果实耐压力和产量有一定的不利影响。对品种石红12,3.0 g/L NaCl处理能显著提高产量,并有增加可溶性总糖、还原糖、Vc含量、果实硬度和耐压力的趋势;6.0 g/L NaCl处理能极显著提高产量,显著增加果实耐压力和Vc含量,但还原糖含量显著降低;9.0 g/L NaCl处理则显著降低果实耐压力和还原糖含量,对其他指标的影响不大。综合各指标分析认为,NaCl处理加工番茄的适宜质量浓度为3.0-6.0 g/L。     

Overexpression of the apple expansin-like gene MdEXLB1 accelerates the softening of fruit texture in tomato

Fruit firmness is an important quality trait of apple fruit texture, and the pre-harvest ripening period is the key period for the formation of apple fruit texture. Expansin is a cell wall loosing protein family that has four subfamilies: α-expansin (EXPA), β-expansin (EXPB), expansin-like A (EXLA), and expansin-like B (EXLB). In this study, we investigated the key period of pre-harvest texture formation in ‘Golden Delicious’ apples based on fruit longitudinal diameter, transverse diameter, firmness, tissue structure, respiration intensity, ethylene release rate, and expansin activity. Within the 10 days before harvest, the fruit was found to reach maturity. Semi-quantitative RT-PCR revealed that most of the expansins were expressed at the ripening stage before harvest. The biological function of the EXLB subfamily gene, MdEXLB1, was further identified, and its subcellular localization on the cell wall was confirmed by transient transformation experiments. Compared with the wild type (WT), the transgenic tomato lines overexpressing MdEXLB1 had lower plant height, earlier fruiting period, fewer days for fruit ripening, higher fruit maturity, lower fruit firmness, higher fruit expansin activity, more discrete flesh cell structure, and accelerated fruit ripening process. Overall, this is the first study to propose that the apple EXLB subfamily gene, MdEXLB1, has biological functions and plays an important role in promoting fruit ripening and softening.     

苹果3个早熟品种果实发育后期硬度及其相关生理指标的初步研究

 以‘泰山早霞’、‘极早红’和‘辽伏’3个早熟苹果品种为试材,研究果实发育期间果实硬度、细胞壁水解酶及淀粉酶活性、乙烯释放量的变化,旨在为探讨果实软化机理提供基本资料,并为早熟苹果品种软化的调控奠定基础。结果表明：① 3个参试品种果实发育过程中果实硬度基本均呈下降趋势,但品种间下降的幅度存在明显差异,其中‘辽伏’花后75 d硬度的下降幅度为35%,‘泰山早霞’50%,‘极早红’53%;② 3个品种果胶甲酯酶（PE）和淀粉酶（Amylase）活性差异不明显,‘泰山早霞’、‘极早红’的多聚半乳糖醛酸酶（PG）、纤维素酶（Cx）活性明显高于‘辽伏’,3个品种PG酶、Cx酶活性变化与其果实硬度变化呈显著负相关;③ 3个参试早熟苹果品种果实发育过程中,乙烯释放量与PG酶、Cx酶活性呈显著正相关。     

长采收期桃果实硬度变化与相关激素含量关系的研究

为探讨长采收期桃-双久红果实成熟前后硬度变化与相关内源激素的关系,以普通桃品种—川中岛为对照,在果实成熟前后各20d对其果肉硬度和内源IAA、ABA、CTK、GA3的含量和乙烯释放量进行了测定。结果表明:随着果实的成熟,川中岛果实的硬度迅速下降,双久红果实的硬度则一直保持较高的水平;川中岛果实的乙烯释放量在成熟后5d出现高峰,而双久红则一直处在较低的水平;川中岛桃果肉中IAA、ABA含量、ABA/IAA值均明显高于双久红的,ABA含量与果实硬度呈显著负相关;随成熟度的加大,两类型桃果肉中CTK、GA3含量都呈下降趋势,但双久红桃果肉中的CTK、GA3含量明显高于川中岛的。     

土壤条件对挖坑机动态力学参数的影响

为研究土壤条件 (土壤类型、土壤湿度、土壤硬度 )对挖坑机动态力学参数 (扭矩、进给阻力 )的影响 .该试验采用模拟生产条件的方法 ,在自行研制的试验台上实现动态实时记录 .通过数据分析 ,得出各影响因素与钻头动态力学参数间的数学关系 ,做出曲线拟合方程 ,从而找到最佳值 ,为挖坑机的设计、选择及运用 ,提供理论依据 .     

床垫软硬度对不同体型人群体压分布的影响

人体体型特征和床垫的软硬度是影响床垫使用舒适性的重要因素。运用人体体压分布测试系统,探究不同软硬度的床垫对仰侧卧姿势下瘦型、中等体型和胖型3种体型受试者体压分布的影响。结果发现,仰侧卧时,瘦型、中等体型和胖型体型受试者肩部、腰部和臀部的接触面积变化趋势一致,均呈现增大趋势。且仰卧下三体型受试者各部位的平均压力的整体变化趋势大致相同,侧卧时仅瘦型和中等体型受试者三部位的平均压力变化趋势大体一致。另外仰卧时床垫硬度的变化对胖型受试者腰部和臀部平均压力影响较大,对瘦型受试者的体压分布面积指数影响较大,对中等体型受试者腰部平均压力影响最小。侧卧时,床垫硬度的变化对胖型受试者腰部的平均压力影响较为显著,对中等体型受试者的三部位平均压力影响最小。