Three citrus varieties, namely Newhall navel, the hybrid citrus Ehime, and Jiuyuehong navel, were examined for 21 sensory attributes, 12 nutritional components, and 73 volatile compounds. On this basis, multidimensional quality analysis was performed using multivariate statistical analysis to determine key differential compounds and establish a variety identification model. The results indicated that Newhall exhibited the highest values of longitudinal diameter, fruit navel size, peel thickness, firmness, soluble solids content (SSC), titratable acidity (TA), total flavonoids, citric acid, tartaric acid, and VC content. Ehime had the thinnest peel, lowest firmness, highest edible ratio and SSC/TA ratio, and highest malic acid content. Jiuyuehong exhibited the largest fruit transverse diameter and highest a* value, along with the highest glucose, fructose, and total carotenoid contents. Principal component analysis (PCA), correlation analysis, and cluster analysis collectively identified five core non-volatile quality indicators: peel color difference index (CI), transverse diameter, single fruit mass, SSC, and VC content. A total of 73 volatile compounds were detected across the three varieties, with terpenes being the most abundant, primarily limonene and valenene. Based on variable importance in projection (VIP) > 1 and P < 0.05, eight volatile core quality indicators were selected: valencene, limonene, (+)-nootkatone, γ-selinene, α-guaiene, γ-gurjunene, β-selinene, and β-guaiene. Using the 13 core quality indicators selected, a partial least squares discriminant analysis (PLS-DA) model was constructed. The variety identification accuracy reached 100% for both the training and test sets, demonstrating that these core quality indicators effectively retain and characterize the majority of quality differences among the three citrus varieties. These findings provide data support for citrus quality evaluation, variety classification, and consumer purchasing decision.

In view of the current research situation of antibiotic water pollution in Baiyangdian Lake and relying on the current scientific research projects, a research type experiment is designed for the adsorption of ciprofloxacin in water by the hydrothermal synthesis of composite aerogel (CMC/CoNiFe-LDH) modified with cobalt nickel iron layered hydroxide (CoNiFe-LDH) based on carboxymethyl cellulose (CMC). The morphology, phase, and functional groups of CMC/CoNiFe-LDH are characterized using SEM, XRD, FTIR, etc. The effects of pH, reaction time, and initial concentration on adsorption efficiency are analyzed. The experimental results indicated that under the optimal experimental conditions, the adsorption capacity of CMC/CoNiFe-LDH for ciprofloxacin is 298.32 mg/g. The teaching experiment involves analytical chemistry, material chemistry, instrument analysis and other curriculum knowledge, which helps stimulate students’ interest in experimental learning, cultivate innovative thinking and experimental hands-on ability, and improve the ability to use theoretical knowledge to solve practical problems.

Ion chromatography was used to investigate the effects of γ-ray irradiation dose, vitamin C (VC) content and niacinamide content on nitrite degradation in aqueous solution and spiced donkey meat, and the volatile components of irradiated spiced donkey meat were analyzed by gas chromatography-ion mobility spectrometry. The results showed that γ-ray irradiation could effectively degrade nitrite in both aqueous solution and spiced donkey meat. A synergistic effect was observed when γ-ray irradiation and VC were used together. Nicotinamide had an inhibitory effect on the irradiation degradation of nitrite in aqueous solution, but had a synergistic effect on the irradiation degradation of nitrite in spiced donkey meat. Nitrite ions in aqueous solution were converted to nitrate ions by the irradiation. After 8 or 10 kGy irradiation, the contents of hexanal and heptanal increased, and donkey meat had an off-flavor. This study provides technical support and a theoretical basis for the degradation of nitrite in spiced donkey meat by γ-ray irradiation.