Freeze drying and spray drying for the retention of the active components, L-theanine and caffeine, and antioxidant activity of tea-based ingredients
Bibliographic record
Abstract
Abstract Preserving food products from oxidation improves their quality and stability. This study compares the effects of storage on L-theanine, caffeine, moisture content and antioxidant activity of spray-dried and freeze-dried white tea infusions. The antioxidant activities of both dried infusions were restored over a 60-day storage. On Day 60, the L-theanine and caffeine levels of the freeze-dried samples were respectively 1.45 ± 0.03 mg mL−1 and 2.23 ± 0.04 mg mL−1 compared with 1.16 ± 0.03 mg mL−1 and 1.97 ± 0.01 mg mL−1 on Day 0. In the spray-dried samples, the L-theanine was 0.32 ± 0.01 mg mL−1 on Day 60 and 0.36 ± 0.02 mg mL−1 on Day 0, while caffeine remained unchanged. Regarding undried/control samples, L-theanine and caffeine declined from respectively 0.29 ± 0.0004 mg mL−1 and 0.33 ± 0.01 mg mL−1 on Day 0 to 0.2 ± 0.001 mg mL−1 and 0.26 ± 0.02 mg mL−1 on Day 60, associated with a decrease in DPPH activity from 75.87% (Day 0) to 15.34% (Day 60). Freeze-drying and spray-drying tea infusions yielded functional products with stable antioxidant activity and moisture. Both drying techniques are reliable for preserving tea preparations.
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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".