|Baldwin, Elizabeth - Liz|
|Cameron, Randall - Randy|
Submitted to: Subtropical Technology Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/16/2010
Publication Date: N/A
Technical Abstract: ‘Hamlin’ orange juice was extracted with a fresh-squeeze juicer with or without pasteurization and compared to commercially processed juice for the flavor and nutritional quality. Fresh juice had much higher peel oil content, but lower insoluble solids and pectin contents than in the commercial juice. Fresh-squeezed juice had less cloud loss due to higher peel oil content and lack of pectin methylesterase activity. Titratable acidity (TA) was higher and thus the ratio of soluble solids to TA was lower in fresh squeezed juice. Fresh juices had higher concentration of hexanal, octanal, 2-methylpropanol, hexanol, cis-3-hexenol, trans-2-hexenol, octanol, a-pinene, sabinene, myrcene, methyl butanoate and ethyl butanoate, most of these associated with high peel oil content. There was no difference between samples for preference, sweetness, and sourness in sensory evaluation. However, sensory panel scores were higher for freshness and lower for “cooked flavor” for fresh juice. The majority of water soluble flavonoids including hesperidin, narirutin, narirutin 4'-glucoside, 6,8-di-C-glucosyl apigenin and isosakuranetin rutinoside, exhibited higher levels in commercially processed juice. On the other hand, flavonoids associated with peel oil, such as quercetagetin hexamethyl ether, sinensetin, nobiletin, tetramethyl-scutellarein, heptamethoxyflavone and tangeretin, had much higher concentrations in fresh squeezed juice due to the high oil content. Commercially processed juice had generally higher limonoids and alkaloids, and total phenolic content. Pasteurization of fresh squeezed juice caused a slight decrease in the organic acids, but did not influence levels of other compounds. The results indicate that squeezing and finishing process rather than pasteurization were major factor in influencing orange juice flavor and nutrient quality.