Food Science Institute, Kansas State University, Manhattan, KS, 66506, U.S.A.
USDA Eastern Regional Research Center, Wyndmoor, PA, 19038, U.S.A.
J Food Sci. 2020 Sep;85(9):2745-2753. doi: 10.1111/1750-3841.15359. Epub 2020 Aug 15.
Dried sweet potatoes (SPs) are often irradiated for improved safety and shelf life. Formation of irradiation-derived radicals was analyzed using electron paramagnetic resonance (EPR) spectroscopy. These irradiation-specific radicals can be used to characterize the irradiation history of dry plant-based foods containing cellulose and sugars. The signal characteristics (intensity and peak shape) were evaluated at different sample locations (skin and flesh), as a function of sample preparation method (grinding, sieving, and pelletizing). The signal intensity was quantified using a double integration method of the peaks based on the area under the curve. The sieving caused ca. 50% decrease in total signal intensity as compared to nonsieved samples due to loss of cellulose-based radicals. The flesh of irradiated SP showed complex EPR spectra with multiple satellite peaks of cellulose radicals (333.5 and 338.8 mT) and split peak of dextrose radicals (337.4 mT); while skin spectra were distinctive of cellulose radicals. In this study, we demonstrated the effects of sample composition and preparation method on formation and analysis of irradiation-specific radicals based on EPR. PRACTICAL APPLICATION: In the last decade or so, there have been health concerns related to the consumption of irradiated pet food products. Electron paramagnetic resonance spectroscopy can be used to analyze the irradiation history of dry products containing cellulose and sugar, such as the popular dog treat dried sweet potatoes, to ensure the products were irradiated within safe limits. This work demonstrates that the formation of irradiation-specific radicals is affected by the sample location (skin and flesh) and moisture content.
干红薯（SPs）通常经过辐照以提高安全性和延长保质期。使用电子顺磁共振（EPR）光谱分析了辐照衍生自由基的形成。这些辐照特异性自由基可用于表征含有纤维素和糖的干植物性食品的辐照历史。评估了不同样品位置（皮和肉）的信号特征（强度和峰形），作为样品制备方法（研磨、筛分和制粒）的函数。使用基于曲线下面积的峰双积分方法定量了信号强度。与未筛分的样品相比，筛分导致总信号强度降低了约 50%，这是由于纤维素基自由基的损失。辐照后的 SP 肉显示出复杂的 EPR 光谱，具有纤维素自由基的多个卫星峰（333.5 和 338.8 mT）和葡萄糖自由基的分裂峰（337.4 mT）；而皮肤光谱则以纤维素自由基为特征。在这项研究中，我们展示了样品组成和制备方法对基于 EPR 的辐照特异性自由基的形成和分析的影响。实际应用：在过去十年左右的时间里，人们对食用辐照宠物食品产品的健康问题表示担忧。电子顺磁共振光谱可用于分析含有纤维素和糖的干产品的辐照历史，例如流行的狗零食干红薯，以确保产品在安全范围内辐照。这项工作表明，辐照特异性自由基的形成受样品位置（皮和肉）和水分含量的影响。
