Antioxidant Activity of Polyphenolics from a Bearberry-Leaf (<i>Arctostaphylos uva-ursi</i> L. Sprengel) Extract in Meat Systems
Bibliographic record
Abstract
Bearberry-leaf ( Arctostaphylos uva-ursi L. Sprengel) extract possesses marked antioxidant activity in model and meat systems. A crude ethanolic extract of bearberry leaves was dechlorophyllized using a silicic acid column, and then fractionated by Sephadex LH-20 column chromatography using ethanol (95%, v/v) and acetone (50%, v/v) as the mobile phases. According to a mass balance, the ethanol fraction comprised 79.2% of the starting material, while the acetone fraction consisted of 9.7%. The content of total phenolics for the fractions and subfractions ranged from 2135 to 9110 Abs 725 units/g extract. Even though the acetone fraction was only ca . 10% of the crude extract, its vanillin response was five times greater than that of the ethanol fraction. According to a mass balance of this fraction, ca . 50% of the polyphenols remained in the aqueous phase when partitioned between water and ethyl acetate. Results showed that the crude bearberry-leaf extract, and its fractions inhibited TBARS formation in cooked meat systems after seven days of refrigerated storage by 97.0, 49.1 and 100%, respectively, when added at a 200-ppm concentration. The ethanol fraction exhibited a classical dose response: when incorporated in meat systems at levels of 200- and 500-ppm before thermal processing, TBARS development was inhibited by 49.7 and 93.9%, respectively, after seven days. This [ethanol] fraction was further subdivided into vanillin-positive constituents; the vanillin-positive fraction possessed weak antioxidant activity in meat model systems, and in some cases demonstrated a slight pro-oxidant effect. The acetone fraction also showed a classical dose response. When added to meat systems at levels of 25-, 50- and 100-ppm, TBARS formation was inhibited by 36.7, 91.4 and 100%, respectively, after seven days of refrigerated storage. It was interesting to note that a subfraction from the acetone product, which was soluble in ethyl acetate but did not have a positive reaction with vanillin, imparted strong antioxidant activity in meat systems. Therefore, vanillin-positive reaction constituents ( i.e., condensed tannins) are not solely responsible for the antioxidant activity observed from the bearberry-leaf extract.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".