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Title:Characterization of blackcurrant berries (Ribes nigrum) and the evaluation of their bioactive compounds after ultrasound-assisted water extractions, enzymatic treatments, and fermentation
Author(s):Cortez, Regina E.
Advisor(s):de Mejia, Elvira
Department / Program:Food Science & Human Nutrition
Discipline:Food Science & Human Nutrition
Degree Granting Institution:University of Illinois at Urbana-Champaign
water-based ultrasound-assisted extraction
Abstract:Blackcurrants (Ribes nigrum) (BC) have remained relatively unknown to the US market because they were prohibited from being grown in the US from the early 20th century until the 1980s. This was due to significant losses by the lumber industry, which discovered that some native and non-native species of the Ribes genus could act as vectors for the fungus Cronartium ribicola. Currently, some US farmers have a renewed interest in this high-value crop because BC and BC products are trending worldwide. BC are known to possess higher concentrations of anthocyanins (ANC) than other similarly colored berries, such as blueberries and blackberries. BC are also a rich source of phytochemicals which are potent antioxidants, antimicrobials and have anti-inflammatory properties; all of which add to the attractiveness of BC and their use in functional foods. The objective was to characterize the whole fruit, and its component parts, of four varieties of BC and their effect on the activities of α-amylase, α-glucosidase, DPPIV, as biochemical markers of diabetes. In addition, the antioxidant capacity was measured using 2,2- diphenyl-1-picrylhydrazyl (DPPH·), after water-based ultrasound assisted extraction, treatment with pectinase and fermentation. BC varieties (Titania, D16-6-54, Consort, and D16-8-14) were dissected into parts (juice, seeds, skins) freeze dried, ground and kept at -20 ºC. Parts and whole berries were evaluated to determine total anthocyanins (TA), total polyphenols (TP), total condensed tannins (TT), and HPLC quantification after 2, 4, 6 h sonication extraction. For LC-ESI-MS analyses, BC samples were extracted with methanol-HCl, sonicated for 1 h, kept overnight at 4 ºC; aliquots were filtered and analyzed. The highest concentrations of TA were found in the skins of Titania, Consort, and D16-8-14 with no statistical difference among them (19.0 ± 2.0, 19.7 ± 2.7, and 20.3 ± 3.5 mg eq C3G/g dry weight (DW), respectively) (p > 0.05). The largest concentrations of TP were seen in the seeds of Titania and D16-8-14 with no statistical difference among them (34.4 ± 1.3 and 34.6 ± 0.5 mg eq GA/g DW, respectively) (p > 0.05). Condensed tannins were found to have the largest concentrations in the skins of all BC (Titania, 391.8 ± 0.0; D16-6-54, 438.2 ± 0.1; Consort, 472.4 ± 0.0; and D16-8-14, 521.0 ± 0.5 mg eq catechin/g, DW). A total of four anthocyanins (delphinidin 3-O-rutinoside, delphinidin 3-O-glucoside, cyanidin 3-O-rutinoside, cyanidin 3-O-glucoside) were identified across all samples. All four varieties of BC showed that the dominant compounds are the rutinoside forms of both delphinidin and cyanidin. Titania skins demonstrated the greatest α -amylase inhibition at 94.8% inhibition. The seeds of Titania, D16-6-54 and Consort all had the highest % inhibition of α -glucosidase with no significant differences among them (97.9 ± 0.0, 97.9 ± 0.2, and 97.9 ± 0.0, respectively). Enzymatic treatment doses and heating times (52 °C) were evaluated for their effect on the concentration of ANC and it was determined that a dose of 400 mL/ton held for 150 min at 52 °C yielded the highest concentration of ANC. Positive correlations were noted between the total time (min) of heating (52 °C) and TT and TP (r = 0.725 and r = 0.731, respectively at α = 0.05). Positive correlations were also noted for the fermentation temperatures (23 °C and 15 °C) for TA, TT, and TP (r = 0.608, r = 0.569, and r = 0.546, respectively at α = 0.05). Juices and skins from all four cultivars had the lowest IC50 values (most potent) for α-amylase inhibition, while the fermented products had the lowest IC50 values for α-glucosidase inhibition. IC50 values for the inhibition of DPPIV were similar for all four cultivars. All four varieties differed in concentrations of specified phenolic compounds and showed potential for biological activity.
Issue Date:2019-04-26
Rights Information:Copyright 2019 Regina E. Cortez
Date Available in IDEALS:2019-08-23
Date Deposited:2019-05

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