Abstract Determining the index for monitoring the freshness of green pepper during storage is still a challenge to be solved in research to avoid food loss, linked to the economical loss. The aim of the present study was to investigate the potentiality of fluorescence spectroscopy for the determination of the freshness index. Time series fluorescence characteristics from different parts of green pepper (Capsicum annuum L.) at different temperatures of storage were determined. Three replicate measurements of Excitation and Emission Matrix (EEM) fluorescence were conducted on every single evaluation during 20 days of storage with a 1-day interval starting from day 4 after harvest. Physical evaluation of color change, firmness, and weight loss were observed to have a correlation with the EEM fluorescence intensity. It was observed that fluorescence components could be extracted from green pepper, the intensity of chlorophyll-a EEM significantly dropped after day 16th from 2822 a.u and 2810 a.u to 2038 a.u and 2106 a.u in day 20th stored at 20 °C and 4 °C respectively as well as the color change behaved the same as the R/G value increased from 0.541 and 0.535 to 0.655 and 0.610 at 20 °C and 4 °C respectively. Finally, it is suggested that two suspected flavonoids substances with EEM 230-nm/310 nm and 270-nm/310 nm are potential to be a probe for freshness index in green pepper as the ratio of these EEMs increased linearly during storage with R2 0.96 and R2 0.91 for both temperatures 20 °C and 4 °C respectively.

中文翻译：

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不同贮藏温度下青椒不同部位荧光时间序列监测

摘要 确定青椒贮藏期间新鲜度监测指标仍是研究中需要解决的一个挑战，以避免食品损失，与经济损失相关。本研究的目的是研究荧光光谱法测定新鲜度指数的潜力。测定了不同贮藏温度下青椒（Capsicum annuum L.）不同部位的时间序列荧光特性。在 20 天的储存期间，从收获后第 4 天开始，每隔 1 天对每次评估进行激发和发射矩阵 (EEM) 荧光的三次重复测量。观察到颜色变化、硬度和重量减轻的物理评价与 EEM 荧光强度相关。观察到在20℃和4℃保存的青椒中可以提取荧光成分，叶绿素-a EEM强度在第16天后从2822 au和2810 au显着下降到第20天的2038 au和2106 au以及颜色变化与 R/G 值在 20°C 和 4°C 下分别从 0.541 和 0.535 增加到 0.655 和 0.610 的表现相同。最后，表明 EEM 为 230-nm/310 nm 和 270-nm/310 nm 的两种疑似黄酮类物质有可能成为青椒新鲜度指数的探针，因为这些 EEM 的比例在 R2 0.96 的储存期间呈线性增加和 R2 分别为 20 °C 和 4 °C 时的 0.91。u 到 2038 au 和 2106 au 分别在 20 °C 和 4 °C 下储存，颜色变化与 R/G 值在 20 °C 和 4 时分别从 0.541 和 0.535 增加到 0.655 和 0.610 表现相同℃。最后，表明 EEM 为 230-nm/310 nm 和 270-nm/310 nm 的两种疑似黄酮类物质有可能成为青椒新鲜度指数的探针，因为这些 EEM 的比例在 R2 0.96 的储存期间呈线性增加和 R2 分别为 20 °C 和 4 °C 时的 0.91。u 到 2038 au 和 2106 au 分别在 20 °C 和 4 °C 下储存，颜色变化与 R/G 值在 20 °C 和 4 时分别从 0.541 和 0.535 增加到 0.655 和 0.610 表现相同℃。最后，表明 EEM 为 230-nm/310 nm 和 270-nm/310 nm 的两种疑似黄酮类物质有可能成为青椒新鲜度指数的探针，因为这些 EEM 的比例在 R2 0.96 的储存期间呈线性增加和 R2 分别为 20 °C 和 4 °C 时的 0.91。