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。     

储藏期与储藏压力对稻谷籽粒压缩特性的影响研究

利用质构仪压缩稻谷籽粒的短轴来测定稻谷籽粒的压缩特性。测定的稻谷储藏在不同的时间与压力下。实验结果表明:当储藏时间为60 d且储藏压力由0 kPa增加到300 kPa,稻谷籽粒的破坏力由81.6 N减小到73.8 N,破坏能由8.10 mJ减小到6.27 mJ,破坏应变由0.139减小到0.117,表观接触弹性模量由171.3 MPa减小到57.7 MPa,最大接触应力由40.8 MPa减小到19.1 MPa。当稻谷储藏压力为77、100、139、200 kPa且储藏时间由0～60 d,稻谷籽粒的破坏力由81.6 N分别减小到79.6、79.1、78.2、77.0 N;破坏能由8.10 mJ分别减小到7.55、7.35、7.08、6.85 mJ;破坏应变由0.139分别减小到0.131、0.128、0.126、0.121;表观接触弹性模量由171.3 MPa分别减小到136.0、121.8、110.6、83.3 MPa;最大接触应力由41.2 MPa分别减小到35.0、32.5、30.3、15.0 MPa。结果表明储藏压力与储藏时间对稻谷籽粒的压缩特性有重要的影响。     

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.     

Young’s Modulus and Poisson’s Ratio Changes in Japanese Radish and Carrot Root Tissues during Boiling

Young’s modulus and Poisson’s ratio changes in Japanese radish and carrot during boiling were examined. Young’s modulus decreased rapidly within 2 min, then the decrease moderated. Carrot (3.0 to 0.5 MPa) exhibited increased modulus values relative to radish (1.8 to 0.3 MPa) during the same boiling period. Poisson’s ratio decreased slightly during boiling; carrot Poisson’s ratio (0.40 to 0.33) was smaller than radish (0.35 to 0.23) during the same boiling period. Boiling in saline solutions increased moduli reductions under the same treatment conditions. These results indicated that carrot maintained hardness, but reduced volume relative to radish during boiling.     

基于AFM的轻微损伤对冬枣力学特性变化的影响研究

为研究轻微损伤对采后贮运过程中冬枣细胞组织结构的影响,分析微力学环境下细胞的力学特性。以冬枣为对象,分别进行了撞击、静压模拟损伤试验,并与正常枣果进行对照,利用原子力显微镜(Atomic Force Microscopy,AFM)力谱模式对3种枣果果肉组织进行了纳米级的力学特性测试,基于赫兹理论模型分析了力-位移曲线,计算单元杨氏模量,获得了刚度分布图,探讨了不同轻微损伤方式下枣果果肉组织力学特性变化的差异性,并分析了原因。结果显示,正常无损枣果平均杨氏模量为1034.0195 kPa,远高于受撞击损伤后枣果平均杨氏模量12.1918 kPa以及受静压损伤后枣果平均杨氏模量45.5503 kPa,且正常无损枣果与撞击损伤枣果、正常无损枣果与静压损伤枣果的杨氏模量值分别存在显著差异,P<0.05;而静压损伤枣果与撞击损伤枣果的杨氏模量值则无显著差异,表明枣果基于不同机械损伤会引起不同程度的细胞微观力学变化,且撞击损伤对枣果品质影响最大。结果可为采后枣果加工贮运技术开发提供理论依据。     

Firmness characteristics of mango hybrids under ambient storage

A study was conducted to determine firmness of eight mango hybrids obtained from the crosses between Amrapali and Sensation and correlate it with TSS and peel thickness. The firmness was determined at top, middle and bottom positions of the fruit using TA + Di Texture Analyzer. The peel firmness at middle position of the hybrids varied from about 20 to 33 N on harvest day, which decreased to 5–12 N with increase in storage period. On 7th day of storage, the peel firmness became almost equal from top to bottom positions indicating the even ripening of fruit. Pulp firmness was found to vary from about 5 to 20 N of freshly harvested fruit, which reduced to 0.3–3.5 N during storage. Peel firmness of 5 N and pulp firmness of 0.3 N was found as threshold points below which the fruit may not be acceptable for consumption.     

Instrumental measurement of pomegranate texture during four maturity stages

Texture of pomegranate fruit and arils are the main quality attributes in the food process industries. In this study, the texture properties of pomegranate fruit and arils (cv. “Ashraf”) at four different stage of maturity (88, 109, 124, and 143 days after full bloom) were evaluated using the puncture test (rupture force and rupture energy) and compression test (bioyield force, rupture energy, and young modulus). The tests showed that all studied textural parameters were sensitive textural parameters for distinguishing the maturity stages. Rupture force and rupture energy of pomegranate fruit were determined at top, middle, and bottom positions of the fruit. The results showed that compression load values of aril increased with advances in maturity stage of fruit, while puncture load values of fruit decreased. The textural properties of pomegranate fruit and arils exhibited a strong dependence (p < .05) on the degree of maturity at harvesting time. Also results showed that rupture force of three different studied positions of fruit was severely different. The highest and lowest values were observed at top and middle position, respectively.     

烟草托盘育苗钵苗力学性能试验

为设计机械化取苗机构,以山东农业大学温室大棚培育的“革新一号”移栽期烟草钵苗为试验材料,在万能试验机上对烟苗进行了钵苗拔取、烟苗茎秆拉伸、压缩、弯曲和剪切力学性能试验。结果表明,营养基质含水率为（52.70±6.50）%时,烟苗拔取力为（2.09±1.28）N;烟苗茎秆含水率为（85.15±2.21）%时,烟苗茎秆抗拉强度为（1.96±0.68）MPa;烟苗茎秆径向抗压强度以及底部、中部的轴向抗压强度分别为（0.096±0.043）、（1.20±0.34）、（1.28±0.28）MPa;简支梁、悬臂梁弹性模量分别为（0.0042±0.0018）、（0.0130±0.0062）MPa;剪切强度为（1.64±0.39）MPa。此结果为机械化取苗机构的设计提供了理论依据。     

Microstructural Study,Tensile Properties,and Scanning Electron Microscopy Fractography Failure Analysis of Various Agricultural Residue Fibers

This paper presents an approach to examine the microstructural properties and mechanical behavior of coconut husks, banana pseudo-stem, pineapple leaf, and sugarcane bagasse fibers by scanning electron microscope and mini-tensile tester, respectively. Single fiber bundles were examined by using scanning electron microscope. Tensile tests were performed at different diameters (0.15–0.55 mm) and gauge lengths (10, 15, 20, and 30 mm/min) to assess the effects of diameter and gauge length on tensile properties. It was found that fibers consisted of different types of regularly arranged cells. The tensile strength (310 MPa) and Young’s modulus (7.4 GPa) of pineapple leaf fiber bundles showed the highest value compared to the other fibers. The tensile strength and Young’s modulus decreased with the increase of diameter and gauge length of fiber bundles. Scanning electron microscopic fractography analysis showed comparatively heterogeneous ruptures associated with more participants of microfibrils for pineapple leaf and banana pseudo-stem fibers compared to coconut husk and sugarcane bagasse fibers. These fractographic observations were discussed in the light of current knowledge of the microstructure of each fiber and the corresponding mechanical properties.     

EFFECTS OF BARLEY FLOUR, WET GLUTEN AND LIQUID SHORTENING ON THE TEXTURE AND STORAGE CHARACTERISTICS OF CHAPATI

The texture of fresh and stored chapati was evaluated using a tensile deformation test. Chapaties were prepared by adding barley flour (0; 10 and 20% w/w), wet gluten (0; 15 and 30% w/w) and liquid shortening (0; 1.5 and 3% v/w). The extensibility, load to rupture, energy to rupture and deformation modulus for fresh control chapati was 8.2 mm, 2.3 N, 0.0297 J and 0.249 MPa which changed to 3.2 mm, 2.85 N, 0.0087 J and 0.790 MPa on storage for 24 h. Wet gluten, barley flour and liquid shortening in various combinations markedly improved the quality of fresh as well as stored chapati. A regression model (R² 0.83 - 0.99) was developed and the coefficients can be used to estimate the textural behaviour of chapati.     

EVALUATION OF THE TEXTURAL PROPERTIES OF JAPANESE PEAR

The texture of Japanese pear (Pyrus serotina Rehder var. culta 'Housui') during fruit enlargement and ripening was evaluated. From the plate compression test, only the deformation ratio, modulus of elasticity, and relaxation were the interpretable textural indices for the Japanese pear. From the puncture test, interpretable textural indices were the rupture force, deformation at the rupture point, toughness, average firmness, initial firmness, apparent modulus of elasticity, bioyield force, penetrating force and penetrating energy in the flesh. The skin of the Japanese pear contributed 70–80% of the firmness of the fruit. As the fruits enlarged, the strain decreased, the elasticity increased, the fruit skin was more prone to mechanical damage, the fruit flesh became softer, and firmness and rigidity of the whole fruit was reduced.     

Comparison of Microbial Inactivation and Rheological Characteristics of Mango Pulp after High Hydrostatic Pressure Treatment and High Temperature Short Time Treatment

The effects of high hydrostatic pressure (HHP) treatments at pressures of 300–600 MPa for 1–20 min and of high-temperature, short-time (HTST) treatment on the inactivation of natural microorganisms in blanched mango pulp (BMP) and unblanched mango pulp (UBMP) were investigated. No yeasts, molds, or aerobic bacteria were detected in BMP or UBMP after HHP treatments at 300 MPa/15 min, 400 MPa/5 min, 500 MPa/2.5 min, and 600 MPa/1 min and HTST treatment at 110 °C/8.6 s. Therefore, these conditions were selected to study the effects of HHP and HTST treatments on pectin methylesterase (PME) activity, water-soluble pectin (WSP) levels, and the rheological characteristics of UBMP and BMP. HHP treatment at a pressure of 600 MPa for 1 min significantly reduced PME activity in UBMP and significantly activated PME in BMP, whereas pressures of 300–500 MPa activated PME regardless of blanching. However, PME activity was reduced by 97 % in UBMP and was completely inactivated in BMP by HTST treatment. WSP levels were significantly decreased by HHP treatment but were increased by HTST treatment in UBMP and BMP. Both HHP and HTST treatments increased the viscosity, storage modulus, and loss modulus of UBMP and BMP. No significant changes in total sugar, total soluble solids, titratable acid, or pH were found after any treatment.     

Free fall analysis of orange fruit using numerical and experimental methods

In this research, the behavior of orange fruit under impact cases was investigated by finite-element modeling in SolidWorks simulation and experimental dropping tests. The values of 0.584 MPa and 0.24 were experimentally determined for modulus of elasticity and Poisson’s ratio as a pre-requirement for simulation. In the simulation tests, orange fruits were dropped from two different heights of 2 and 3 m with a drop angle of 45° relatives to a rigid plane. Experimental tests were also conducted to validate simulation results. Maximum equivalent stress and contact force were obtained from simulation results 0.5826 MPa and 14.95 N, respectively.     

Influence of cultivar,storage and cooking on the mechanical properties of winter squash (Cucurbita maxima)

Texture profile analysis and rupture tests were carried out on raw and cooked tissues of ‘Delica’, ‘CF 2’ and ‘CF 4’ buttercup squash cultivars and ‘Red Warren’ pumpkin during storage. The raw tissues of ‘CF 2’ were the firmest, exhibiting high tissue strength (high failure force) combined with less rigidity, ie lower modulus of deformability (MOD) and higher compressibility (high strain and deformation at failure). ‘Red Warren’ had the least firm tissues combined with high rigidity and low compressibility. The firmness of ‘Delica’ and ‘CF 4’ tissues was intermediate. The texture parameters such as MOD, failure force, hardness, gumminess and chewiness measured on raw and cooked tissues of the four cultivars showed no significant differences up to 2 months of storage but then decreased (P < 0.05) between 2 and 3 months of storage. The size of the cells and thickness of the parenchyma cell walls among ‘Delica’, ‘CF 2’ and ‘CF 4’ were similar. The greater size of ‘Red Warren’ parenchyma cells, larger intercellular spaces and thinner cell walls appear to account for its lower tissue strength compared with the other cultivars. Copyright © 2004 Society of Chemical Industry     

Effects of different storage techniques on rupture properties of kiwifruits

Storage of harvested agricultural products under optimum storage conditions is very important for selling them as an intended price in the market and for the maintenance of their quality longer. On the other hand, different storage techniques effects the resistance properties of products. In this research, some rupture properties like, maximum force and bioyield force, stress, maximum energy in maximum force, maximum energy in bioyield point, modulus of elasticity, bioyield deformation, maximum breaking dilatation and minimum damage height, of ‘Hayward’ kiwifruits stored under four different storage conditions (Normal Atmosphere; 21 % O₂ + 0 % CO₂ (NA as Control), NA storage after 1-Methylcyclopropene treatment (1-MCP + NA), NA storage with ethylene control (NA + EC), Controlled Atmosphere storage (2 % O₂ + 5 % CO₂) with ethylene control (CA + EC) and under two different load conditions were evaluated. Both under two load conditions rupture properties of kiwifruits stored under CA + EC conditions were measured higher than other storage conditions. In particular, maximum force and modulus of elasticity values of CA-stored kiwis were found to be statistically important.     

挤压对灵武长枣应力应变影响的有限元分析

为了分析灵武长枣在采摘过程中内部应力应变对挤压的响应规律,为采摘机器人的设计提供理论依据,本文利用万能力学试验机在15、20、25、30、35 mm/min五种不同挤压速率下对灵武长枣整果进行了横向和纵向压缩,对力-变形曲线进行拟合,求得长枣在压缩破裂时的刚度及破裂力,并对15和35 mm/min两种横向挤压速率进行了有限元模拟,建立了有限元模型。结果表明:灵武长枣在受到挤压时,其力学性能具有各向异性,横向的抗压能力更强。横向压缩时,整果破裂负载为214.34~266.53 N,弹性模量为14.90~17.05 MPa,相对变形量为20.70%~22.67%;纵向压缩时,整果破裂负载为132.52~185.40 N,弹性模量为4.59~6.07 MPa,相对变形量为13.72%~17.25%。受力点的应力应变在果肉中是最大的,并沿赤道向果核周围延伸,且逐渐减小。压缩速率为15 mm/min的有限元模型的模拟值与其实验值的偏差为14.98%,35 mm/min的偏差为11.06%。运用有限元法对灵武长枣挤压模拟是可行的。     

Effect of Hydrocolloids on the Dehydration Kinetics,Color, and Texture of Mango Leather

Abstract

Tray drying of mango pulp was carried out to prepare mango leather and the dehydration behavior was studied. Different hydrocolloids like guar gum, pectin, carboxymethyl cellulose, gum acacia, pectin, and sodium alginate were also added to the mango pulp at levels of 1, 2, and 3% w/w to determine their effects on drying rate, moisture ratio, color, and equilibrium relative humidity. Texture of mango leather was studied using tensile deformation. Hydrocolloids lowered the drying rate of mango leather but only during the initial 2 h of drying. Mango leather had an extensibility, peak force to rupture, deformation modulus and energy to rupture of 14.54 mm, 0.0036 kN, 0.2285 MPa, and 0.0369 J respectively. Hydrocolloids increased the extensibility and energy to rupture of mango leather. Yellowness and redness of samples was lowered but lightness of mango leather was not significantly affected by hydrocolloid addition. The equilibrium relative humidity of mango leather increased with increasing hydrocolloid concentration. The study revealed that hydrocolloids especially guar gum or pectin can be added to modify the texture of mango leather without significantly affecting the drying rate, color, and packaging requirements.     

Effect of Rot-Retardant Treatment on Properties of Jute Fibers

Jute natural fiber is gradually replacing traditional glass fibers as reinforcement in composites due to their higher specific modulus and lower specific gravity. For reducing rotting properties of jute fiber, rot-retardant treatment was conducted on different portions of the fiber. The rot-retardant jute fibers were characterized by tensile test, Fourier transform infra-red spectroscopy, scanning electron microscopy, X-ray diffraction analysis, and thermal and water absorption tests. The tensile properties improved in the middle portion as compared to the top and bottom portions and deteriorated after rot-retardant treatment. The diameter gradually increased from top to middle and then to bottom portion after treatment. The crystalinity index was found higher for bottom portion. Thermal properties of jute fiber also improved as compared to the control jute fiber. The rot-retardant--treated jute fiber may find satisfactory and desirable application in our house hold accessories.     

The Effects of Moisture Content, Compression Speeds, and Axes on Mechanical Properties of Walnut Cultivars

In this study, the mechanical properties of walnut (Juglans regia L.) cultivars were investigated as a function of moisture content. The experiments were carried out at three moisture contents, compression speeds (0.5, 1, and 1.5 mm/s), and compression axes (X-, Y-, and Z-axes). The highest rupture force and rupture power in all moisture contents were obtained for walnut cultivars loaded along the Y-axis. Rupture force, rupture energy, and rupture power of walnuts decreased in magnitude with an increase of moisture content, while rupture force, specific deformation, rupture energy, and rupture power increased with an increase of compression speeds. The highest rupture force was obtained with load along the Y-axis as 410.4 N and 394.3 N and also the highest rupture force was recorded at 1.5 mm/s compression speed as 260.7 N and 377.1 N for Yalova-1 and Yalova-3 cultivars, respectively. A linear force decrease was observed from 320.5 N to 196.4 N and from 492.7 N to 247.1 N with increasing moisture content from 11.46% to 23.16% and from 11.25% to 19.47% for Yalova-1 and Yalova-3, respectively. The highest rupture force, specific deformation, rupture energy, and rupture power were obtained at 1.5 mm/s compression speed, while the lowest rupture force was obtained at 0.5 mm/s compression speed for walnut cultivars. The lower rupture force and rupture power were obtained with load along Z-axis for Yalova-1 and Yalova-3 walnut cultivars. The results revealed that the higher compression speed and Z-axis could be recommended for cracking of shelled walnuts.     

链格孢侵染采后甜瓜病程相关蛋白基因表达及酶活性变化规律

以伽师瓜和86-1甜瓜为试材,损伤接种链格孢菌,比较两种甜瓜果皮与果肉抗病性差异。甜瓜果实接种链格孢,（7±1）℃、相对湿度85%～90%冷库贮藏,测定病斑直径,观察病斑组织显微结构,实时聚合酶链式反应比较CmGLU、CmCHT1、CmCHT2相对表达量,测定几丁质酶（chitinase,CHT）和β-1,3-葡聚糖酶（β-1,3-glucanase,GLU）活性。结果表明：链格孢侵染两种甜瓜,伽师瓜病斑直径小于86-1甜瓜,果皮小于果肉,第30天时,86-1甜瓜果皮和果肉病斑直径是伽师瓜的1.28 倍和1.29 倍;观察病斑组织显微结构,发现伽师瓜和86-1甜瓜果皮通过细胞壁增厚抵御链格孢侵染,果肉组织细胞壁抵抗能力较弱,侵染末期果皮与果肉组织细胞壁分层、皱缩,细胞内布满菌丝体和分生孢子,部分果肉细胞解体,无法辨认细胞结构;伽师瓜CHT和GLU基因始终高于86-1甜瓜,果皮高于果肉,CmCHT1相对表达量在侵染初期至侵染中期较高,CmCHT2相对表达量在侵染中期较高,表明病原菌在侵染初期至侵染中期诱导了CHT基因的表达;CmGLU相对表达量在侵染中期至侵染末期较高,表明病原菌在侵染中期至侵染末期诱导了GLU基因的表达;链格孢侵入伽师瓜和86-1甜瓜后,果皮和果肉组织CHT和GLU活性随贮藏时间延长呈升高-降低的变化趋势,伽师瓜高于86-1甜瓜,果皮高于果肉。表明伽师瓜更强的抵御能力与CHT、GLU基因与酶活性密切相关。