Edwards Kara M, Badiger Aishwarya, Heldman Dennis R, Klein Matthias S
Department of Food Science and Technology, The Ohio State University, Columbus, OH 43210, USA.
Metabolites. 2021 Jun 25;11(7):419. doi: 10.3390/metabo11070419.
The current date labeling system for pasteurized milk is based on the predicted growth of spoilage microorganisms, but inherent inaccuracies and the inability to account for environmental factors (e.g., temperature fluctuations) contribute to household and retail food waste. Improved shelf-life estimation can be achieved by monitoring milk quality in real-time. In this study, we identify and quantify metabolites changing over storage temperature and time, the main factors affecting milk stability. Pasteurized 2% fat milk was stored at 4, 10, 15, and 20 °C. Metabolite change was analyzed using untargeted and targeted nuclear magnetic resonance (NMR) metabolomics approaches. Several metabolites correlated significantly to storage time and temperature. Citric acid decreased linearly over time at a temperature-dependent rate. Ethanol, formic acid, acetic acid, lactic acid, and succinic acid increased non-linearly after an initial period of minimal increase. Butyric acid exhibited strong inverse temperature dependencies. This study provides the first analysis of the effect of time and temperature on the concentration of key metabolites during milk storage. Candidate molecules for shelf-life monitoring have been identified, and the results improve our understanding of molecular changes during milk storage. These results will inform the development of real-time shelf-life indicators for milk, helping to reduce milk waste.
目前巴氏杀菌牛奶的日期标注系统是基于对腐败微生物生长的预测，但由于存在固有误差且无法考虑环境因素（如温度波动），导致家庭和零售食品出现浪费。通过实时监测牛奶质量可以实现更准确的保质期估计。在本研究中，我们识别并量化了随储存温度和时间变化的代谢物，这些是影响牛奶稳定性的主要因素。将含2%脂肪的巴氏杀菌牛奶分别储存在4、10、15和20°C下。使用非靶向和靶向核磁共振（NMR）代谢组学方法分析代谢物变化。有几种代谢物与储存时间和温度显著相关。柠檬酸随时间呈线性下降，下降速率与温度有关。乙醇、甲酸、乙酸、乳酸和琥珀酸在最初一段极小的增加期后呈非线性增加。丁酸表现出强烈的负温度依赖性。本研究首次分析了时间和温度对牛奶储存过程中关键代谢物浓度的影响。已确定用于保质期监测的候选分子，研究结果增进了我们对牛奶储存过程中分子变化的理解，并将为开发牛奶实时保质期指标提供依据，有助于减少牛奶浪费。
