The effect of thermal treatments on the quality and aroma of watermelon juice was evaluated. Watermelon juice was pasteurized via ultrahigh temperature (UHT, pasteurized at 135°C for 2 s), low temperature long time (LTLT, pasteurized at 60°C for 30 min), and high temperature short time (HTST, pasteurized at 100°C for 5 min), respectively. UHT and LTLT reduced the total flora count and maintained the color of the pasteurized juice, while the HTST led to a significant color difference. A total of 27, 21, 22, and 21 volatiles were identified in the unpasteurized juice, UHT, LTLT, and HTST, respectively. The typical watermelon aroma, including (3Z)-3-nonen-1-ol, (E)-2-nonen-1-ol, 1-nonanal, (2E)-2-nonenal, and (E,Z)-2,6-nonadienal, was abundant in the LTLT. Consequently, the aroma of the LTLT was similar to that of unpasteurized juice. Moreover, the shelf life of the LTLT reached 101 and 14 days at 4 and 25°C, respectively. Hence, the LTLT was the best way to maintain the quality and aroma of watermelon juice.

To date, the foliar anthocyanin content was either determined via the pH differential or HPLC methods, both of which are slow and destructive. Here, a hyperspectral model was established to estimate the foliar anthocyanin content of purple corn (Zea mays L. var. Jingzi No. 1). The reflectivity (P) of the foliar hyperspectral was inverted to 1/P, lg P, 1/lg P, , , , and . The correlation coefficient between these inversions and the foliar anthocyanin content was plotted against the hyperspectral wavelength. The wavelength of inversions around 650 nm was sensitive to the foliar anthocyanin content. The hyperspectral model was fitted via linear, polynomial, power, exponential, and logarithmic functions with the sensitive band as independent variable and the anthocyanin content as function. The hyperspectral model (y = 3,000,000,000 × W₆₈₅^4.5896) fitted via inversion of showed the highest determination coefficients (0.768) among all models. The hyperspectral model was well validated with a determination coefficient of 0.932 and an RMSE of 0.0065. Moreover, the accuracy and stability of the hyperspectral model were further enhanced with a determination coefficient of 0.954 and RMSE of 0.0047 when the anthocyanin content of the sample was below 20 mg/g. Hence, the hyperspectral model estimated the foliar anthocyanin content of purple corn quickly and nondestructively.