稻谷籽粒的压缩特性与储藏压力关系的实验研究

本文选取南粳5055品种稻谷为实验样品,使其在6个LHT-1型回弹模量仪中储藏2个月,顶部分别加载50 kPa、100 kPa、150 kPa、200 kPa、250 kPa和300 kPa。利用Brookfield质构仪对回弹模量仪装样筒内的顶部与底部样品进行压缩实验。实验结果表明：储藏2个月,储藏压力为0-300 kPa,稻谷籽粒的最大破坏力、最大破坏能、最大破坏应变、表观接触弹性模量和最大接触应力的变化范围分别为81.58 N-3.78 N,8.10 mJ-6.27 mJ,0.1392-0.1168,71.32 MPa-57.68 MPa, 40.84 MPa-19.11 MPa。随着稻谷储藏压力的增加,最大破坏力、最大破坏能、最大破坏应变、表观接触弹性模量和最大接触应变皆减小。     

稻谷籽粒的压缩特性与储藏压力关系的研究

选取南粳5055品种稻谷为试验样品,使其在6个LHT-1型回弹模量仪中储藏2个月,顶部分别加载50、100、150、200、250和300 k Pa。利用Brookfield质构仪对回弹模量仪装样筒内的顶部与底部样品进行压缩实验。结果表明:储藏2个月,储藏压力为0~300 k Pa,稻谷籽粒的最大破坏力、最大破坏能、最大破坏应变、表观接触弹性模量和最大接触应力的变化范围分别为81.58~3.78 N,8.10~6.27 MJ,0.139 2~0.116 8,71.32~57.68MPa,40.84~19.11 MPa。随着稻谷储藏压力的增加,最大破坏力、最大破坏能、最大破坏应变、表观接触弹性模量和最大接触应变皆减小。     

储藏压力对大豆籽粒压缩特性的影响研究

用2个LHT-1型粮食回弹模量仪储藏大豆6个月,顶部分别加载150 kPa和300 kPa,理论计算得到粮食回弹模量仪的储粮筒内不同位置的压力(87、115、150、161、211、300 kPa).利用质构仪对不同储藏压力下的大豆样品进行压缩试验.运用SPSS软件对数据进行分析处理,得出大豆籽粒压缩的最大破坏力(76.77～101.51 N),最大破坏能(68.28～84.12mJ),表观弹性模量(131.99 ～200.29 MPa).结果表明:随着储藏压力的增大,大豆籽粒压缩的最大破坏力,最大破坏能,表观弹性模量逐渐减小.     

储藏条件对大豆籽粒力学特性的影响

选取黑龙江大豆,使其储藏60、90、120、150 d,储藏温度分别为20、25、30℃,储藏籽粒的含水率分别为12.0%、13.5%、15.0%,使用Brookfield质构仪测定了不同储藏温度、不同含水率、不同储藏时间的大豆籽粒的最大破坏力、最大破坏力能、最大破坏应变。试验结果表明:储藏60 d,储藏温度为20~30℃,储藏籽粒的含水率为12.0%~15.0%,大豆籽粒压缩最大破坏力、最大破坏能、最大破坏应变的变化范围分别为:106.85~90.19 N、160.80~108.92 mJ、0.356~0.412;储藏150 d,储藏温度为20~30℃,储藏籽粒的含水率为12.0%~15.0%,大豆籽粒压缩最大破坏力、最大破坏能、最大破坏应变的变化范围分别为:99.19~81.50N、113.01~90.52 mJ、0.439~0.472;在相同的储藏温度、储藏时间条件下,大豆籽粒的压缩最大破坏力、最大破坏能随着含水率的增加而减小,最大破坏应变随着含水率的增加而增加;在相同的含水率、储藏时间条件下,大豆籽粒的压缩最大破坏力、最大破坏能随着储藏温度的增加而减小,最大破坏应变随着储藏温度的增加而增加;在相同的储藏温度、含水率条件下,大豆籽粒的压缩最大破坏力、最大破坏能随着储藏时间的增加而减小,最大破坏应变随着储藏时间的增加而增加。     

压缩速度与压缩方位对大豆籽粒压缩特性的影响研究

按照美国农业与生物工程师协会ASAE S368.4DEC2000(R2006)标准,使用Brookfield质构仪测定了黑龙江大豆籽粒(2011年产)的表观弹性模量、最大破坏力、最大破坏力能、破坏时的变形量。试验选定压缩速度为:0.02、0.1、0.5、1.0 mm/s,选定压缩方位为长轴(X轴)、中轴(Y轴)、短轴(Z轴)。由质构仪软件,得到了加载载荷与对应变形量的关系曲线,运用spass软件对数据进行分析处理,得到大豆的表观弹性模量、最大破坏力、最大破坏能、破坏时的变形量。试验结果表明:随着压缩速度的增加,大豆籽粒沿长轴(X轴)、中轴(Y轴)、短轴(Z轴)压缩的最大破坏力增大,最大破坏能增加,压缩变形量增大,表观弹性模量减小。     

不同储藏条件下筒仓中大豆堆高安全域研究

建立筒仓中大豆分层压缩平衡微分方程,实验测定微分方程中的参数,数值求解压缩平衡微分方程得到筒仓内大豆堆应力分布值;建立筒仓中大豆籽粒堆放模型,求解大豆籽粒堆放模型得出筒仓内大豆堆应力与籽粒压力的关系;实验测定大豆籽粒压缩力与塑性应变关系;设定大豆籽粒产生0.4 %的塑性应变为籽粒损伤阈值,结合筒仓内不同深度大豆堆应力、籽粒压力与塑性应变,给出大豆的堆高安全域。计算与实验结果表明：含水率为8.58%～15.01% w.b.并且储藏时间为60 d～240 d的大豆,在半径为10 m的筒仓内安全堆高的范围是47.6 m～20.6 m;在半径为15 m的筒仓内安全堆高的范围是40.2 m～19.3 m;在半径为20 m的筒仓内安全堆高的范围是37.4 m～18.8 m;筒仓内大豆堆的安全堆高随着含水率的增大而减小,随着筒仓直径的增大而减小,随着储藏期的增大而减小。     

稻谷储藏期脂质陈化的研究进展

稻谷陈化是一个复杂的过程,涉及到稻谷籽粒的各项理化性质的变化。淀粉、蛋白质和脂质是稻谷的三大主要成分,直接影响稻谷的食用品质。在储藏过程中,脂质易发生氧化、分解等反应。脂质陈化产生大量游离脂肪酸,使得稻谷品质变差。该文详细论述了稻谷储藏过程中脂质陈化的机理、影响因素,并对稻谷的储藏提出了建议。     

平房仓中稻谷密度的时空分布值及堆高沉降特性研究

使用粮食回弹模量仪测定出稻谷堆的压缩密度与最大主应力（竖直压应力）及储藏时间的关系模型。选定修正剑桥模型作为稻谷堆的应力与应变关系本构方程,使用有限元方法计算出装粮后瞬时平房仓中稻谷层的竖直压应力分布值。由平房仓中稻谷堆各层的竖直压应力和稻谷堆的压缩密度与最大主应力（竖直压应力）及储藏时间的关系模型计算出平房仓中稻谷层的密度与粮层深度及储藏时间的关系模型。结果表明：稻谷堆压缩密度随最大主应力的增加而增大,随储藏时间的增加而增大,稻谷堆压缩密度关于储藏时间和最大主应力的关系模型是 ;平房仓中稻谷层密度随粮层深度的增加而增大,随储藏时间的增加而增大,平房仓中稻谷堆密度关于储藏时间和粮层深度的关系模型是 ;平房仓中稻谷堆高随储藏时间的增加而降低,且堆高降低幅度越来越小,最后稻谷堆高趋于稳定值。     

糙米储藏中品质特性变化及调控研究进展

糙米为稻谷脱去稻壳后产生的颖果,含有谷维素、谷胱甘肽、γ-氨基丁酸、米糠多糖等多种功能性成分,营养价值高。与稻谷储藏相比,糙米储藏具有提高仓容利用率、减小运输压力、改善仓储条件等优势。但由于糙米没有外层稻壳的保护,在储藏过程中品质更容易发生劣变。该文综述糙米在储藏过程中色泽、质构特性、发芽率、生活力、水分含量、电导率、脂肪酸值、丙二醛含量、酶类、热特性、糊化特性等的变化趋势,分析糙米品质劣变机理,为糙米的储藏提供参考。     

储藏对稻谷代谢产物的影响研究

利用气相色谱-质谱联用(GC-MS)技术对查哈阳地理标志稻米保护区的稻谷样本以及储藏1年后的稻谷样本进行代谢组学研究,探讨储藏对稻谷代谢产物的影响。本实验采用主成分分析和正交偏最小二乘法-判别分析的多元统计分析以及层次聚类分析等方法对数据进行分析。结果显示,2021年和储藏样本分别定性到147、148个代谢产物,在数量上相差不大,但种类上存在差异。共筛选出39个差异代谢产物,层次聚类分析发现储藏前后稻谷代谢物的含量呈现反向变化趋势。代谢通路分析共筛选出8条与代谢物差异相关性最高的通路,可作为研究储藏对稻谷代谢通路影响中的参考物质。     

The effect of storage pressure on the mechanical properties of paddy grains

To investigate the effect of storage pressure and storage time on the mechanical properties of paddy grains, an experimental study was carried out to determine the mechanical properties of paddy grains compressed at minor axis orientation using the Texture Analyzer. The paddy grains were stored under different pressures and for different time. The results showed that as the storage pressure increased from 0 to 300 kPa, the rupture force of paddy grains stored for 60 days decreased from 81.58 to 73.78 N, the rupture energy from 8.10 to 6.27 mJ, the rupture strain from 0.1392 to 0.1168, the apparent contact modulus of elasticity from 171.32 to 57.68 MPa and the maximum contact stress from 40.84 to 19.11 MPa. All of the mechanical properties of the paddy grains exhibited a linear relationship with storage pressure. As for the paddy grains stored under the pressures of 77, 100, 139, 200 kPa, as the storage time increased from 0 to 60 days, the rupture force of the paddy grains decreased from 81.58 to 79.58 N, 81.58 to 79.12 N, 81.58 to 78.21 N and 81.58 to 76.96 N; the rupture energy decreased from 8.10 to 7.55 mJ, 8.10 to 7.35 mJ, 8.10 to 7.08 mJ and 8.10 to 6.85 mJ; the rupture strain decreased from 0.1392 to 0.1309, 0.1392 to 0.1283, 0.1392 to 0.1257 and 0.1392 to 0.1213. The apparent contact modulus of elasticity decreased from 171.32 to 135.97 MPa, 171.32 to 121.77 MPa, 171.32 to 110.59 MPa and 171.32 to 83.32 MPa; the maximum contact stress decreased from 41.16 to 35.00 MPa, 41.16 to 32.45 MPa, 41.16 to 30.32 MPa and 41.16 to 14.97 MPa, respectively. The results revealed that both storage pressure and storage time have a significant effect on the mechanical properties of paddy grains.     

Effect of Loading Position and Storage Duration on the Textural Properties of Eggplant

Eggplant has a very limited shelf life and, like other vegetables, is susceptible to different types of damage during and after harvest operations. Besides, eggplant is inhomogeneous considering its inner construction point of view. It is therefore important to specify how storage might affect their mechanical properties and how they vary in morphology. In this work, eggplants were divided into three portions along the longitudinal axis and their textural properties were separately investigated using different types of test over a 10-day period of storage. The results showed that the tension strength, rupture force and Young’s modulus of skin tissue decreased with increasing the length of storage period, and they were generally different in the different portions of the fruit that were sampled. The values of Young’s modulus and rupture force of pulp tissue taken from compression tests decreased from 1.466 to 0.821 MPa and 20.70 to 17.66 N for upper section, 0.637 to 0.536 MPa and 15.33 to 13.13 N for middle section and 0.518 to 0.422 MPa and 14.19 to 12.19 N for bottom section, respectively, with the increase in storage period. Similarly, as the samples were stored longer, the Young’s modulus and rupture force of their combined skin and pulp tissues, obtained from penetration tests, decreased from 3.01 to 2.02 MPa and 31.21 to 24.95 N for upper section, 2.59 to 1.66 MPa and 28.64 to 21.66 N for middle section and 1.91 to 1.15 MPa and 23.18 to 17.37 N for bottom section, respectively.     

减压处理对菜花贮期生理效应的影响

研究不同强度减压处理对菜花贮期生理效应的影响。菜花在(1.0 ± 0.5)℃条件下贮藏40d,每隔24h 采用不同压力处理并维持此压力。结果表明：处理压力为60.7kPa 时呼吸强度比对照降低43%,PPO 和POD 活性分别比对照降低了28.8% 和32.7%,而VC 含量比对照高55.6%,褐变指数仅为0.21。适宜的压力处理能延缓菜花组织褐变和衰老,较好地保持其贮藏品质,具有良好的保鲜效果。     

不同减压处理对圣女果贮藏品质的影响

将圣女果分别放在101.3 kPa(常压)、80、50、20 kPa下,每4 d测定相关指标,研究减压处理对圣女果贮藏品质的影响。结果表明:减压处理可降低采后圣女果的失重率、呼吸强度,抑制Vc含量、可滴定酸含量、可溶性固形物含量、原果胶含量的降低,减缓细胞质膜透性、花青苷含量的上升,从而保持了其贮藏期的品质,延缓其衰老速率,其中以50 kPa处理效果佳。     

优质稻谷氮气气调与常温储藏品质变化的比较研究

本文研究了优质稻谷在氮气气调储藏条件下的品质变化,并与常温储藏的品质变化做对比,以期为优质稻谷氮气气调储藏下的储备周期提供依据。将优质稻谷黄华占和两优于氮气气调和常温两种储藏方式下储藏,每两个月检测两种优质稻谷的脂肪酸值、品尝评分值、出糙率、整精米率、黄粒米率、直链淀粉含量、过氧化氢酶活动度、发芽率、糊化特性和质构特性的变化。实验结果表明：氮气气调储藏480 d(16个月)的优质稻谷的劣变程度与常温储藏420 d(14个月)的劣变程度相当。说明氮气气调储藏与常温储藏相比,能在一定程度上延缓优质稻谷的品质劣变,但效果有限。建议氮气气调储藏的优质稻谷的储备周期为16个月。     

Relation between mechanical properties and structural changes during osmotic dehydration of pumpkin

This work presents the changes in the mechanical properties of pumpkin (Cucurbita pepo L.) fruits when submitted to osmotic dehydration processes. Cylinders of the parenchymatic tissue were dehydrated with sucrose solutions, varying the concentration (30–60% w/w) and temperature (12–38 °C) of the osmotic solution and process time (0–9 h). As an opposite process to dehydration, water soaking of some cylinders was also performed. Samples were submitted to uniaxial compression until rupture, and four parameters were analyzed: apparent modulus of elasticity, true stress at failure, Hencky strain at failure and failure work (toughness). Values of these mechanical properties for fresh material ranged from 0.96 to 2.53 MPa for apparent modulus of elasticity, 250–630 kPa for failure stress, 0.42–0.71 for failure strain and 85–285 kJ/m³ for toughness. Mechanical properties of osmodehydrated samples showed no dependence on concentration of the osmotic solution and process temperature, whereas they were found to be dependent on moisture content: apparent elastic modulus decreased and failure strain increased during dehydration; toughness and failure stress initially decreased with moisture content, and increased at advanced stages of the process. Water soaked samples showed a decrease in failure strain, failure stress and toughness, but the apparent elastic modulus increased. Simultaneous structural observation during compression showed that the material fails in the contact zones of its fibres. This fact and the observed structural profiles during dehydration could explain the changes in the failure properties (strain, stress, toughness) along the studied processes. Changes in the apparent modulus of elasticity were likely related with the changes in the turgor pressure of cells.     

Effects of PICS bags on insect pests of sorghum during long-term storage in Burkina Faso

The PICS bags, originally developed for cowpea storage, were evaluated for sorghum (Sorghum bicolor) preservation. Batches of 25 kg of sorghum grain were stored in 50 kg PICS or polypropylene (PP) bags under ambient conditions for 12 months and assessed for the presence of insect pests and their damage, seed viability and, oxygen and carbon dioxide variations. The grain was incubated for 35 days to assess whether any insects would emerge. After six months of storage, oxygen levels decreased in the PICS bags compared to polypropylene bags. After 12 months of storage, only two pests, Rhyzopertha dominica and Sitophilus zeamais were found in the PICS bags. However, in PP bags there were additional pests including Tribolium castaneum and Oryzeaphilus mercator and Xylocoris flavipes. Grain weight loss and damage caused by these insects in the PP bags were significantly higher compared to those stored in PICS bags. Germination rates of sorghum grains stored in PP bags decreased significantly while no changes were observed in grains stored in PICS bags when compared to the initial germination. After the incubation post storage period, there was a resurgence of R. dominica in sorghum grains from PICS bags but the population levels were significantly lower compared to polypropylene bags. PICS bags preserved the quality and viability of stored sorghum grains and protected it from key insect pests. The PICS technology is effective for long-term sorghum storage but the potential resurgence of insects in low-oxygen environment calls for further research.