METABOLOMIC AND MICROBIAL PROFILING OF TROPICAL/SUBTROPICAL FRUITS AND SMALL FRUITS FOR QUALITY FACTORS AND MICROBIAL STABILITY
Location: Citrus and Other Subtropical Products Research
Title: Effect of Extraction, Pasteurization and Cold Storage on Flavonoids and other Secondary Metabolites in Fresh Orange Juice
Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 28, 2013
Publication Date: N/A
Interpretive Summary: Fresh orange juice is perceived to be more wholesome than processed juice. Fresh juice may have nutrients and phytonutrients that differ from pasteurized or processed juice. To evaluate this, orange juice from two varieties was made by commercial extraction, using a commercial fresh juicer, or hand squeezed. Each type of juice had its advantages with commercially extracted juice having higher levels of some healthful compounds and the fresh juices higher levels of others, although the commercially extracted juice had higher levels of bitter compounds. The commercial fresh juicer resulted in more peel oil in the juice and subsequently higher levels of some oil-soluble antioxidants.
Fresh orange juice is perceived to be more wholesome than processed juice. Fresh juice may have nutrients and phytonutrients that differ from pasteurized or processed juice. To evaluate this, 'Hamlin’ and ‘Valencia’ oranges were extracted using a commercial food service juicer, pasteurized or not, resulting in fresh-commercial juice (FCJ) or pasteurized FCJ (FCPJ) for comparison with pasteurized processed juice (PPJ) in 2009, and gently hand-squeezed ‘Valencia’ juice (HSJ) in 2010 for nutrient and phytonutrient content. Regardless of pasteurization, FCJ/FCPJ contained 4-10 fold higher peel oil and 25-49% lower insoluble solids than the PPJ, while in HSJ, the peel oil content was very low, and the insoluble solids content was in between FCJ and PPJ. The major flavonoid glycosides in orange juice were two-fold higher in PPJ than in FCJ/FCPJ and HSJ, indicating that the extraction and finishing process led to more peel tissue into the juice than fresh juice extraction methods. The total phenolic content (TPC) in the juices followed a similar pattern to the flavonoid glycoside content. The polymethoxylated flavones (PMFs), associated with peel oil, occurred at the highest levels in the FCJ/FCPJ, and lowest in HSJ. Limonoids and alkaloids occurred at higher levels in PPJ and HSJ than in FCJ/FCPJ. The high peel oil in FCJ/FCPJ resulted in higher oil soluble PMFs than were found in PPJ and HSJ, while the more water soluble flavonoid glycosides, limonoids, and alkaloids were higher in PPJ.