Specific reagent kits

Tea polyphenols were purchased from Clooney Tea Technology (Co., Ltd. Ya'an, China) with 98.99% purity. It consists of 50.34% catechin, 45.62% epigallocatechin gallate, 1.45% caffeine and 3.37% moisture.
The ageing corn had been stored for 4 years in the national barns (Jilin, China). The regular corn had been stored for 6 months in a grain depot (Ningxia Province, China). For the ageing corn and regular corn samples, crude protein (CP), dry matter (DM), crude fat (CF) were determined as described by the AOAC International (2006) . Filter bags and the Fiber Analyzer equipment (Fiber Analyzer, Ankom Technology, Macedon, NY, USA) were used to measure the neutral detergent fiber and acid detergent fiber according to Van Soest et al., 1991 (link) with a slight modification. Acidity value was measured by following the national standard method (China GB/T 20570-2015; MAPRC, 2015 ). The activity of catalase and peroxidase were determined using specific reagent kits (Jiancheng Bioengineering Institute, Nanjing, PR China). The mycotoxins and xanthophylls were determined using a high-performance liquid chromatography (HPLC) instrument equipped with a fluorescence detector (Agilent 1100, Agilent Technologies, Santa Clara, CA, USA). Determination of the fatty acid profiles was carried out in regular and ageing corns by HPLC (China GB 5009.168-2016; MAPRC, 2016 ).

The MDA content of egg yolk (n = 6) was determined using specific reagent kits (Jiancheng Bioengineering Institute, Jiangsu, China). Briefly, yolk samples (0.5 g) were homogenized with 4.5 mL of absolute ethanol. Subsequently, 1 mL of the homogenate was treated with thiobarbituric acid, mixed rapidly and heated in a boiling water bath for 40 min. The samples were centrifuged at 10,621 × g for 10 min and the supernatants pipetted into a 96-well plate. The absorbance of the supernatant was measured at 532 nm.