284 Characterization of condensed tannins from freeze-dried, silage, or hay purple prairie clover (Dalea purpurea Vent.): Structure composition, protein precipitation, and anti-Escherichia coli properties
Bibliographic record
Abstract
Conservation methods have been shown to affect forage nutrient composition and value, but little information is available about the effect of forage conservation on plant condensed tannins (CT). The objective of this study was to assess the effects of conservation method on the concentration, chemical composition and biological activity of CT. Whole plant purple prairie clover (PPC; Dalea purpurea Vent.) was harvested at the full-flower stage and conserved as freeze-dried forage (FD), silage (SIL), or hay (HAY). Concentration of CT in conserved PPC was determined by the butanol HCl–acetone method. Structural composition, protein-precipitation capacity, and antibacterial activity of CT isolated from conserved forage were determined by in situ thiolytic degradation followed by liquid chromatography–mass spectrometry analysis, a protein precipitation assay using BSA and ribulose 1,5-disphosphate carboxylase as model proteins, and an Escherichia coli growth test, respectively. Conservation method had no effect on concentration of total CT, but ensiling decreased (P < 0.001) extractable CT and increased (P < 0.001) fiber-bound and protein-bound CT. In contrast, hay increased (P < 0.01) only protein-bound CT. Regardless of conservation method, epigallocatechin (EGC), catechin, and epicatechin (EC) were the major flavan-3-ol subunits, and gallocatechin was absent from both terminal and extension units of PPC CT. The SIL CT had the lowest (P < 0.001) EGC but the highest (P < 0.01) EC in the extension units. Similarly, SIL CT exhibited a lower (P < 0.001) mean degree of polymerization but a higher (P < 0.001) procyanidin:prodelphinidin (PC:PD) ratio than FD or HAY CT. The protein-precipitating capacity of CT in conserved PPC ranked (P < 0.001) as FD > HAY > SIL. Growth of E. coli in M9 medium was inhibited by 25 to 100 µg/mL of CT isolated from FD, SIL, and HAY (P < 0.05), but preservation method had no effect on the ability of CT to inhibit bacterial growth. The results demonstrated that ensiling decreased the extractability and protein-precipitating capacity of CT by increasing the PC:PD ratio. Purple prairie clover conserved as hay retained more biologically active CT than if it was conserved as silage.
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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) | 0.000 | 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".