Noiwan Duangjai, Suppakul Panuwat, Rachtanapun Pornchai
Department of Postharvest Technology, Faculty of Engineering and Agro-Industry, Maejo University, Chiang Mai 50290, Thailand.
Center for Advanced Studies for Agriculture and Food (CASAF), Department of Packaging and Materials Technology, Faculty of Agro-Industry, Kasetsart University, Bangkok 10900, Thailand.
Polymers (Basel). 2022 Sep 1;14(17):3616. doi: 10.3390/polym14173616.
Day-to-day advancements in food science and technology have increased. Indicators, especially biopolymer-incorporated organic dye indicators, are useful for monitoring the ripeness quality of agricultural fruit products. In this investigation, methylcellulose films-containing pH dye-based indicators that change color depending on the carbon dioxide (CO) levels-were prepared. The level of CO on the inside of the packaging container indicated the ripeness of the fruit. Changes in the CO level, caused by the ripeness metabolite during storage, altered the pH. The methylcellulose-based film contained pH-sensitive dyes (bromothymol blue and methyl red), which responded (through visible color change) to CO levels produced by ripeness metabolites formed during respiration. The indicator solution and indicator label were monitored for their response to CO. In addition, a kinetic approach was used to correlate the response of the indicator label to the changes in mango ripeness. Color changes (the total color difference of a mixed pH dye-based indicator), correlated well with the CO levels in mango fruit. In the 'Nam Dok Mai Si Thong' mango fruit model, the indicator response correlated with respiration patterns in real-time monitoring of ripeness at various constant temperatures. Based on the storage test, the indicator labels exhibited color changes from blue, through light bright green, to yellow, when exposed to CO during storage time, confirming the minimal, half-ripe, and fully-ripe levels of mango fruit, respectively. The firmness and titratable acidity (TA) of the fruit decreased from 44.54 to 2.01 N, and 2.84 to 0.21%, respectively, whereas the soluble solid contents (SSC) increased from 10.70 to 18.26% when the fruit ripened. Overall, we believe that the application of prepared methylcellulose-based CO indicator film can be helpful in monitoring the ripeness stage, or quality of, mango and other fruits, with the naked eye, in the food packaging system.
食品科学与技术的日常进步有所增加。指标，尤其是含有生物聚合物的有机染料指标，对于监测农产品水果的成熟度质量很有用。在本研究中，制备了含有甲基纤维素膜的基于pH染料的指标，其颜色会根据二氧化碳（CO）水平而变化。包装容器内部的CO水平表明了水果的成熟度。储存期间由成熟代谢产物引起的CO水平变化改变了pH值。基于甲基纤维素的膜含有对pH敏感的染料（溴百里酚蓝和甲基红），它们（通过可见颜色变化）对呼吸过程中形成的成熟代谢产物产生的CO水平作出反应。监测了指标溶液和指标标签对CO的反应。此外，采用动力学方法将指标标签的反应与芒果成熟度的变化相关联。颜色变化（基于混合pH染料的指标的总色差）与芒果果实中的CO水平密切相关。在“南托迈·西通”芒果果实模型中，在不同恒温下实时监测成熟度时，指标反应与呼吸模式相关。根据储存试验，指标标签在储存期间暴露于CO时，颜色从蓝色变为浅亮绿色再变为黄色，分别确认了芒果果实的未成熟、半成熟和完全成熟水平。果实成熟时，其硬度和可滴定酸度（TA）分别从44.54 N降至2.01 N，从2.84%降至0.21%，而可溶性固形物含量（SSC）从10.70%增加到18.26%。总体而言，我们认为所制备的基于甲基纤维素的CO指标膜的应用有助于在食品包装系统中用肉眼监测芒果和其他水果的成熟阶段或质量。
