Summary Changes in qualities of ‘Red Fuji’ and ‘Golden Delicious’ apples in response to different heat treatments (45 and 60 °C) following cold storage were investigated. Quality indices including firmness, titratable acidity, total phenolic content, antioxidant capacity, colour parameters and microstructure were measured. Results indicated heat treatment at both temperatures for 3‐h hastened loss of titratable acidity in ‘Red Fuji’ and ‘Golden Delicious’ apples, but maintained firmness in both cultivars. However, heat treatment at lower temperature (45 °C) best maintained total phenolic compounds and antioxidant capacity in ‘Red Fuji’ apples throughout storage, whereas there was no difference between heat treatments in ‘Golden Delicious’ apples. Examination by scanning electron microscope (SEM) revealed that the effect of heat treatment at different temperatures on ‘Red Fuji’ and ‘Golden Delicious’ apples was structurally different. Apple tissue that had been heat treated at elevated temperature (60 °C) for 3 h was associated with fractured cell walls and collapse of cells.

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Shanxi aged vinegar differs from other vinegars in that it has a unique thermal process (6 days at 85°C) which creates its typical flavour. The present study evaluated the key aroma compounds of Shanxi aged vinegar made from tartary buckwheat by gas chromatography-olfactometry-mass spectrometry. The influence of the thermal processing on product aroma was also studied. A total of 45 compounds were detected of which 24 were correctly identified while 21 were tentatively identified: the remaining six were unknown. Of the 45 compounds detected, 13 have not been previously reported in other vinegars. Most of the aroma compounds identified increased significantly during the first 3 days of heating and then decreased from the fourth day onwards. The changes may have resulted from different kinds of reactions, such as the Maillard reaction and other associated reactions such as degradation of amino acids. This study would be helpful for optimizing the processing conditions of Shanxi aged vinegar.

Photo-oxidation is one of the main causes of oxidative deterioration in food. Understanding of the mechanisms of photo-oxidation is essential for food science students when pursuing careers in food safety and quality assurance. However, few food chemistry laboratories emphasize photo-oxidation. Thus, we develop a laboratory activity that trains students to evaluate the level of photo-oxidation by monitoring the early (photosensitizer), middle (dissolved oxygen), and late [thiobarbituric acid reactive substances (TBARS) value] indicators of photo-oxidation in a full-fat milk model under two types of light spectra (fluorescent and LED light). Through data analysis and post-laboratory discussion, students well understood the mechanism of photo-oxidation and the effect of light wavelength on the rate of reaction in food products by characterizing the oxidation kinetics at different stages of oxidation. This laboratory was designed for upper-level undergraduate students of food science and technology majors (n = 30), the learning outcome shows that students acquire practical skills in operating instruments that they may encounter in food industry as well as quantitative analytical methods that are used to estimate the shelf life of food products.