冷链物流环境下时间温度指示器的制备与应用

    Preparation and application of time temperature indicator in cold chain logistics

    • 摘要: 为可视化冷链储运过程中桑葚品质和剩余货架期,该研究通过单因素和正交试验调节木糖、甘氨酸、磷酸氢二钾(K2HPO4)浓度配比,实时记录不同配比时间温度指示器(time temperature indicator, TTI)的颜色及吸光度变化规律,寻求最佳浓度配比的TTI,利用傅里叶红外光谱和紫外-可见吸收光谱探究TTI内在机理,并用动力学验证TTI恒温和断链情况下的适用性。结果表明,当木糖浓度为1.00 mol/L,甘氨酸浓度为2.00 mol/L,K2HPO4浓度为1.00 mol/L时TTI的吸光度更高,颜色变化更为均匀,通过阿仑尼乌斯方程得到TTI活化能为40.13 kJ/mol。桑葚在−1~25 ℃的失重率、花青素、硬度、可溶性固形物、可滴定酸和维生素C的活化能分别为36.08、40.42、43.35、38.28、43.72、40.41 kJ/mol,与TTI活化能接近,说明TTI可以很好地监测桑葚的剩余货架期。此外,断链模拟结果显示,桑葚开始腐败时,TTI的颜色到达指示终点,桑葚品质变化与TTI颜色变化一致,且在不同温度波动试验下桑葚各指标和TTI的等效温度小于1 ℃,由此说明,在温度波动情况下TTI可以很好地监测桑葚的品质以及剩余货架期。研究结果可为桑葚在储运过程中提供有效的剩余货架期监测,通过调节TTI的制备参数可改变其使用寿命和适用范围,以匹配不同货架期的食品。

       

      Abstract: Here Maillard reaction time-temperature indicator (TTI) was prepared to observe the quality and remaining shelf life of mulberry during cold chain storage and transportation. The catalysts were used the xylose and glycine as the substrates and K2HPO4. The color change pattern of TTI was explored to adjust the concentration ratio of xylose, glycine, and K2HPO4. The results showed that the glycine concentration was 2.00 mol/L, when the xylose concentration was 1.00 mol/L. The attention of K2HPO4 was 1.00 mol/L, and the absorbance of TTI was higher. There were more stages of discoloration and more uniform discoloration. In addition, the intrinsic mechanism of the color change of TTI was also explored by FTIR and UV-visible absorption spectroscopy. The overall change trend of the spectra was slight with the long storage time of TTI. Still, there was no noticeable change in the FTIR spectra except for the weak difference in peak positions and intensities. The generation of new peaks was absence in the spectrograms. There was the benign effect of the mixture of xylose, glycine, whereas the K2HPO4 solution was produced a soothing effect. Meanwhile, C-O, C-H, C=O, C=C, C=N, amide I, amide II, amide III, C-N, N-H, and C-H were involved in the formation of melanoidin. The UV-vis absorption spectra showed that the absorbance change of TTI increased with the increase of storage time. The higher the temperature was, the shorter the time was required for the appearance of the characteristic peaks of color. The hardness, total soluble solids, titratable acid, and vitamin C in mulberries showed the different decreasing trends with the extension of storage time during refrigerated storage. By contrast, the weight loss rate and anthocyanins showed the increasing trends. Mulberry storage at ice temperature (-1℃) was favorable to maintain the quality of mulberry, which was used as the long-term refrigerated storage. The activation energies of 36.08, 40.42, 43.35, 38.28, 43.72, and 40.41 kJ/mol were calculated from the weight loss, anthocyanin, hardness, total soluble solids, titratable acid and vitamin C contents of mulberry at 25, 15, 10, 4 and -1 °C, respectively. The activation energy of the TTI was fitted to be 40.13 kJ/mol by the Arrhenius equation. There was no more than 25 kJ/mol difference in the calculated activation energy between each quality indicator and the TTI. As such, the quality change of mulberry at different ambient temperatures was more accurately matched with the time-temperature indicator. A chain-breaking simulation experiment was designed to verify the TTI monitoring under temperature fluctuation. Some changes were observed in the TTI color for the mulberry quality under different chain-breaking situations. The results showed that the abuse of temperature was accelerated the color change of TTI, even for the deterioration of mulberry quality. When the TTI color reached the endpoint, the mulberries began to decay. Furthermore, the change in TTI color was consistent with the shift in the mulberry quality. In addition, the kinetic analysis was performed by equivalent temperature. The difference between the comparable temperature values of TTI and each index of mulberry was calculated to be less than 1℃, thus verifying the monitoring ability of TTI. The TTI can be expected to monitor quality of mulberry for the long shelf life.

       

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