Changes in the Physicochemical Characteristics, Free and Bound Aroma Compounds in the Raspberry Juice during Storage

The changes in the physicochemical characteristics of raspberry juice during storage were studied. Free aroma compounds during storage were analyzed by solid-phase microextraction/gas chromatography–mass spectrometry. Bound fractions were isolated and extracted with methanol and Amberlite XAD-2 resin and then hydrolyzed by almond β-glucosidase. The content of the ascorbic acid was reduced by 47 and 31% in fresh and processed juice after 20 days of storage, respectively. A total of 23 free aroma compounds were identified in the raspberry juice. Only 12, 10, 9 and 10 free aroma compounds were found in this juice after 5, 10, 15 and 20 days of storage, with total contents of 1,614, 696, 806 and 1,103 μg/L. C13-norisoprenoids were the predominant compounds during storage. In total, 14 bound aroma compounds were found in this juice. Benzoic acid was the most abundant benzene compound. Most of the bound fractions were missed during storage. Practical Applications Aroma attribute is one of the most important factors to the quality of the fruit juice. It changed seriously during hot processing or storage. The main reason was that the aroma compounds in the juice were transferred, degraded or evaporated. Nevertheless, glycosidically bound aroma compounds might be released during processing or storage. The findings of this research revealed that most of the physicochemical characteristics remained stable during storage, except ascorbic acid. The free and bound aroma compounds of the raspberry juice changed a lot during storage. Most of these compounds decreased or were missed during hot processing and storage. The information gained from this research could be further applied in the raspberry and food industry to improve the quality of the juice during processing and storage.