Presentation Title

Impact of Ultrasonication Time on Antioxidant Capacity of Orange Pomace

Faculty Mentor

Dr. Olive Yao Li, Dr. Gabriel Davidov-Pardo, Dr. Wei Jen Lin, Dr. Yan Liu

Start Date

17-11-2018 1:30 PM

End Date

17-11-2018 1:45 PM

Location

C161

Session

Oral 3

Type of Presentation

Oral Talk

Subject Area

biological_agricultural_sciences

Abstract

Orange pomace (OP) is a by-product from the orange juicing industry and can be utilized for value-added phenolic compounds instead of being discarded which negatively impacts the environment. This study was carried out to investigate the relationship between the antioxidant capacity of OP extract and ultrasonication time. OP was obtained from Cal Poly Pomona Farm Store and underwent size reduction pretreatment. Ultrasound Extraction (UE) (20 kHz) took place using 1:10 w/v of orange pomace to 80% ethanol at power level 5 out of 10 for 210 minutes. Aliquots were tested at 15 min, 30 min, and every subsequent 30 min until 210 min. Total Phenolic Content (TPC) (765 nm), Total Flavonoid (TFC) (415 nm), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (515 nm) colorimetric assays were used to measure antioxidant capacity on a microplate reader. Gallic acid and Quercetin dihydrate were used as standard equivalents in TPC and TFC, respectively. There was a significant (p<0.05) increase from extraction time of 15 min compared to every other extraction time point in GAE and %DPPH Inhibition; however, in TFC, extraction time of 15 min was only significantly (p<0.01) lower compared to 120-210 min. The minimum extraction time that did not differ from 210 min for TPC, TFC, and DPPH was 90, 120, and 150 min, respectively. The maximum %DPPH Inhibition was 80.8 ± 2.6% at 210 min; this was concurrent with the peak values of TPC (6.3 ± 0.4 mg GAE/ g wet OP) and TFC (0.90 ± 0.1 mg QDE/ g wet OP) at the same time. Increased extraction time will unlikely increase the antioxidant capacity significantly. This study investigates optimized antioxidant capacity and extraction time for OP and demonstrates that UE has a high impact in early extraction times, but requires longer extraction times downstream to have a significant difference in antioxidant capacity.

Summary of research results to be presented

A calibration curve was created for both Gallic acid (y=0.0052x+0.0623, R2=0.9982) and Quercetin dihydrate (y=0.008x-0.0498, R2=0.9985), which were used as a standard equivalent for both Total Phenolic Content (TPC) and Total Flavonoid Content (TFC), respectively. Within 15 minutes of extraction, the TPC was 3.6 ± 0.2 mg GAE/ g wet OP, the TFC was 0.5 ± 0.1 mg QDE/ g wet OP, and the %DPPH Inhibition was 56.5 ± 2.4 %. The largest increase in the early extract times was within the first 15 min for TPC, TFC, and DPPH, and between 15 min and 30 min for TPC and %DPPH which was 4.5 ± 0.6 mg GAE/ g wet OP and 63.5 ± 1.9 % at 30 min, respectively; however, for TFC, there was no significant difference from 15 min until the extraction time reached 120 minutes. The maximum TPC, TFC, and %DPPH Inhibition was at the final extraction point (210 min) which was 6.3 ± 0.4 mg GAE/ g wet OP, 0.90 ± 0.1 mg QDE/ g wet OP, and 80.8 ± 2.6%, respectively. These values, however, were not significantly higher than time points 90 min (TPC), 120 min (TFC), and 150 min (DPPH). In both TPC and TFC, the equivalent values approximately doubled from 15 minutes to the final extraction time of 210 min; however, for %DPPH Inhibition, there was only an increase of approximately 30%.

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Nov 17th, 1:30 PM Nov 17th, 1:45 PM

Impact of Ultrasonication Time on Antioxidant Capacity of Orange Pomace

C161

Orange pomace (OP) is a by-product from the orange juicing industry and can be utilized for value-added phenolic compounds instead of being discarded which negatively impacts the environment. This study was carried out to investigate the relationship between the antioxidant capacity of OP extract and ultrasonication time. OP was obtained from Cal Poly Pomona Farm Store and underwent size reduction pretreatment. Ultrasound Extraction (UE) (20 kHz) took place using 1:10 w/v of orange pomace to 80% ethanol at power level 5 out of 10 for 210 minutes. Aliquots were tested at 15 min, 30 min, and every subsequent 30 min until 210 min. Total Phenolic Content (TPC) (765 nm), Total Flavonoid (TFC) (415 nm), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (515 nm) colorimetric assays were used to measure antioxidant capacity on a microplate reader. Gallic acid and Quercetin dihydrate were used as standard equivalents in TPC and TFC, respectively. There was a significant (p<0.05) increase from extraction time of 15 min compared to every other extraction time point in GAE and %DPPH Inhibition; however, in TFC, extraction time of 15 min was only significantly (p<0.01) lower compared to 120-210 min. The minimum extraction time that did not differ from 210 min for TPC, TFC, and DPPH was 90, 120, and 150 min, respectively. The maximum %DPPH Inhibition was 80.8 ± 2.6% at 210 min; this was concurrent with the peak values of TPC (6.3 ± 0.4 mg GAE/ g wet OP) and TFC (0.90 ± 0.1 mg QDE/ g wet OP) at the same time. Increased extraction time will unlikely increase the antioxidant capacity significantly. This study investigates optimized antioxidant capacity and extraction time for OP and demonstrates that UE has a high impact in early extraction times, but requires longer extraction times downstream to have a significant difference in antioxidant capacity.