【作者】 王兴枝；

【导师】 任建武；

【作者基本信息】 北京林业大学 ， 农产品加工及贮藏工程， 2012， 硕士

【摘要】 本文从果蔬采后生理的角度,运用非损伤技术手段,研究了黄瓜在不同贮藏保鲜条件下的水分散失及品质变化,从而将贮藏方法的评价和选取标准数量化,为贮藏黄瓜的品质鉴定和改进贮藏方法提供科学依据。研究结果表明：1、室温条件下,随着贮藏时间的延长,失水程度逐渐加深,从第2天开始黄瓜的阻抗值开始增大；容抗值从第3天开始减小。在保鲜膜条件下,黄瓜的阻抗值在开始的4天内变化相对较小,第5天阻抗值明显增大,第6天之后又趋于平衡状态。在冷藏条件下,黄瓜的阻抗值在前3天表现出增大的趋势,而从第4天开始随水分的散失,阻抗值反而减小。通过对不同贮藏过程中特征频率的研究发现：在室温条件下,随贮藏时间的延长,水分的不断散失,特征频率逐渐减小,而保鲜膜和冷藏条件下的变化较小。通过比较50Hz下旱黄瓜与密刺黄瓜在不同贮藏方式下阻抗特性的变化发现：旱黄瓜的保水能力和抗冻能力比密刺黄瓜强。2、冷藏条件下测得的黄瓜的相对电导率较高,且从第3天开始出现明显的升高趋势,而室温和保鲜膜条件下黄瓜的相对电导率变化不明显。3、室温条件下测得的呼吸强度从第4天开始明显增强,说明此时黄瓜的品质正在发生变化；保鲜膜条件下,黄瓜的呼吸强度始终相对较稳定；冷藏条件下,在开始的前5天内,呼吸相对较稳定,而从第6天开始呼吸强度减弱。4、黄瓜在不同贮藏条件下的近红外光谱图变化不同,室温和保鲜膜条件下,近红外光谱的吸收峰都随贮藏时间的延长而降低,室温下吸收峰的变化远远高于保鲜膜条件。冷藏条件下,开始的一段时间内吸收峰逐渐降低,之后又升高。5、黄瓜中总可溶性糖、可溶性蛋白,维生素C三种营养成分的变化趋势基本一致,且与失水量的变化呈显著负相关,相关系数分别为-0.941*,-0.947*,-0.913*(*：在0.05水平上显著相关)。通过实验证明了用阻抗谱参数反应黄瓜在贮藏保鲜过程中品质变化的可行性。更多还原

【Abstract】 This research subject was aimed at study the relationship between impedance spectroscopy characteristic, respiration, conductivity, near-infrared spectroscopy, total soluble sugar, soluble protein, vitamin C and water loss under different conditions.The results showed that:the change variation of impedance spectrum characteristic with the loss of water was different under different storage conditions. At room temperature, the Rp began to increase from the second day with the degree of water loss gradually deepened; the Cp began to decrease from the third day. Under the condition of plastic wrap, the Rp of cucumber changed little at the first four days, but increased significantly at the fifth day, then became equilibrium state. Under the condition of refrigerated, the Rp increased during the first three days; but, from the fourth day it decreased with moisture loss. The change of characteristic frequency was also different. By comparison different varieties of cucumber’s impedance characteristic, found that, we could compare their water-retention and freezing capacity.The relative conductivity changed greatly by refrigerated from the third day. It changed little under the condition of refrigerated and plastic wrap. The breathing intensity changed greatly at room temperature from the fourth day. At this time, the quality of cucumber had changed, and even became decay. Under refrigeration the respiration intensity decreased from the sixth day.The near-infrared spectra of cucumber under different storage conditions changed differently. The absorption peak decreased with the extension of storage time. At room temperature, the absorption peak changed most than other two conditions. It drop at the beginning then lift by refrigerated.The three nutrients:soluble sugar, soluble protein and vitamin C’s trend were basically same, and linearly with the loss of water.It was proved that it was practicably to react the quality changes of cucumber through impedance spectroscopy parameters, the correlation coefficients were:-0.941*,-0.967*,-0.913*(*:at0.05level was significantly related)更多还原