Effects of cushioning materials on the firmness of Huanghua pears (Pyrus pyrifolia Nakai cv. Huanghua) during distribution and storage

The type and quality of cushioning materials could significantly affect the vibration intensity and physical quality of fruits during transport. In the current paper, we evaluated the different cushioning materials (paper‐wrap materials, foam‐net packages) for their protective effect on the vibration levels, number of bruises and mechanical damage to Huanghua pears (Pyrus pyrifolia Nakai cv. Huanghua) during transport. Changes in pear firmness, hydrolase activity and cell wall constituents were examined in fruits stored for up to 36 days after transport. Our data suggested that the choice of cushioning material significantly reduced the vibration intensity in transit, affecting the physical quality of fruits and their subsequent commercialization, and that foam‐net packages provided a greater protective effect than paper‐wrap packages. Copyright © 2007 John Wiley & Sons, Ltd.     

热固性酚醛树脂移印标识牢固性研究

镀金盖板广泛应用于军品集成电路的气密性封装中,表面标识通常采用油墨移印方式进行打标。移印打标后的电路在经历表贴后易出现标识脱落的问题,导致用户无法辨认。通过研究移印打标过程中采用的热固性酚醛树脂油墨固化机理,确定了电路经历异常高温、助焊剂污染、清洗剂清洗及外力摩擦与标识牢固性的关系,有效指导了表贴厂家在后续表贴时的注意事项。     

低温对不同水分条件下煤的坚固性系数影响研究

煤体力学性质是煤与瓦斯突出的一个必要条件,提高煤体的力学性质对抑制煤与瓦斯突出的发生具有重要的意义。为探析低温环境及水分对煤体坚固性系数的影响,通过煤样加湿处理装置及低温环境坚固性系数测试装置,对不同温度及不同水分条件下煤体的坚固性系数进行测试。研究结果表明:随着温度的升高以及煤样水分的降低,煤的坚固性系数呈减小趋势;随着温度的降低以及煤样水分的升高,煤的坚固性系数呈增大趋势。研究为通过煤层注水加冷冻的措施治理煤与瓦斯突出奠定了理论基础。     

某岩金矿山地应力、覆盖岩层与井巷稳固性的关系研究

介绍了我国南方某黄金矿山采用无底柱分段崩落采矿法,对在开采生产中所遇到的各方面围岩稳固性问题,即矿床开采技术条件、地应力、覆盖岩层与井巷稳固性的关系进行了分析研究,以便于在今后矿山生产中,掌握并应用其规律,达到安全、高效、经济地开发矿产资源之目的。     

Effect of pH on Microstructure and Characteristics of Cream Cheese

ABSTRACT:  This study evaluated the effect of pH on the microstructure of cream cheese and compared pH-induced changes in its microstructure with concomitant changes in cheese firmness and meltability. On 4 different days, experimental batches of cultured hot pack cream cheese were manufactured and analyzed for initial chemical composition. The cheeses were then sectioned into samples that were randomly assigned to 7 different treatment groups. Three groups were exposed to ammonia vapor for 1, 3, and 5 min to increase the pH; 3 groups were exposed to acetic acid vapor for 30, 60, and 90 min to decrease the pH; and 1 unexposed group served as the control. After equilibration at 4 °C, samples were analyzed for pH, firmness, meltability, and microstructure by scanning electron microscopy. The effects of experimental treatments on cheese pH, firmness, and meltability were analyzed by randomized complete block analysis of variance (ANOVA). Relationships between cheese pH and firmness and meltability were evaluated by regression. Experimental treatments significantly affected cheese pH, firmness, and meltability. Cheese firmness decreased and meltability increased with increasing pH from about pH 4.2 to 6.8. Cheese microstructure also changed dramatically over the same approximate pH range. Specifically, the volume of the protein network surrounding the fat droplets increased markedly with increasing pH, presumably due to casein swelling. These data support the hypothesis that protein-to-water interactions increased as the cheese pH increased, which gave rise to progressive swelling of the casein network, softer texture, and increased meltability.     

Texture analysis of raw and cooked tubers of short‐duration lines of cassava by multivariate and fractional conversion techniques

BACKGROUND: Cassava tubers are mainly consumed after boiling in water. Their cooking quality depends on the variety, maturity, growing conditions and physicochemical and starch properties. In this study the textural and gelatinisation characteristics of ten short‐duration lines of cassava were assessed. Textural changes due to cooking were modelled by fractional conversion techniques and correlated with gelatinisation and physicochemical properties by principal component analysis. RESULTS: There was a significant variation (P < 0.05) in the textural properties of tubers and the thermal and pasting properties of flours among varieties. The degree of cooking and relative firmness of tubers were modelled by a linear equation. The thermal softening behaviour was modelled by a dual‐mechanism first‐order kinetic model with rate constant values ranging from 0.106 to 0.190 min^?1. About 69.21% of the total variation in texture profile, gelatinisation and physicochemical parameters could be explained by the first three principal components. CONCLUSION: The results indicated that the textural and gelatinisation properties varied considerably among different varieties. However, the interaction between the components of the tubers and the structural make‐up of the tuber tissues played a more important role than the physicochemical and functional properties. Copyright © 2008 Society of Chemical Industry     

Effect of nitrogen fertilisation levels on melon fruit quality at the harvest time and during storage

BACKGROUND: The quality of melon fruit depends upon many factors that can be affected by growing conditions and post-harvest management. The aim of this work was to investigate the effect of nitrogen fertilisation levels on the fruit quality at harvest time and during storage. Experiments were performed in an open field using melon plants (Cucumis melo L. Var. Reticulatus cv. Prodigio). The nitrogen (N) was applied through fertigation using four fertilisation levels: 0, 55, 110 and 165 kg ha⁻¹. After harvest the fruits were stored at 10 °C for 8 days. At harvest time the yield, flesh firmness, skin and pulp colours, content of carotenoids, total phenols, ascorbic acid (AsA) and ethylene production were measured on fruits differently fertilised. RESULTS: The total marketable fruit yield and fruit nitrogen content linearly increased with N levels. Antioxidant compounds decreased after storage but were not affected by N fertilisation levels. However, total carotenoids, total phenols, and AsA declined during storage. CONCLUSION: All the quality parameters did not appear to be affected by N level at either harvest time or after storage. Therefore it is advisable to reduce nitrogen input for cultivation without compromising quality and yields. Copyright © 2007 Society of Chemical Industry     

煤(岩)坚固性系数测定的准确性和稳定性研究

煤(岩)的坚固性系数(f值)是煤(岩)与瓦斯突出防治过程中的重要参数之一。在理论分析的基础上,首先建立了评价采用捣碎法测定f值测定效果的数学模型,并提出了相应的评价指标,而后通过实验验证了该模型的实用性和准确性。