Abstract
‘Hamlin’ orange juices were prepared using one of following methods: 1) freshly squeezed with a commercial food service squeezer (fresh), 2) freshly squeezed and pasteurized (fresh/pasteurized), and 3) processed with industrial extractor and pasteurized (processed). Samples were taken from the juices directly after extraction and again after 4 d of juice storage at 5 °C for analysis of flavonoids, limonoids, alkaloids, carotenoids, ascorbic acid and total phenolic content. Processed juice had higher levels of insoluble solids, but lower levels of peel oil in comparison to fresh juice regardless of pasteurization. The majority of flavonoid glycosides including hesperidin, narirutin, narirutin 4´-glucoside, 6,8-di-C-glucosyl apigenin and isosakuranetin rutinoside, which are rich in the albedo and segment membranes, occurred at the highest levels in processed juice. In contrast, the polymethoxylatedflavones associated with peel oil, such as quercetagetin hexamethyl ether, sinensetin, nobiletin, tetramethylscutellarein, heptamethoxyflavone and tangeretin occurred at the highest levels in the fresh juices. Limonoids (limonin glucoside, limonin aglycone, nomilin glucoside, nomilinic acid glucoside, and nomilin aglycone), alkaloids (feruloyl putrescine and an unknown alkaloid) and carotenoids (zeaxanthin, lutein, ß-cryptoxanthin, α-carotene and ß-carotene) occurred at higher levels in the processed juice than in the fresh juice regardless of pasteurization. The processed juice had higher total phenolic content but lower ascorbic acid content than the fresh juices. Thermal pasteurization increased the contents of the polymethoxylated flavones, but decreased the contents of carotenoids. During 4-d storage at 5 °C, 20% to 80% of hesperidin, narirutin, narirutin 4´-glucoside and isosakuranetin rutinoside precipitated in the processed juice but not the fresh juice.
