Individual and sequential effects of stirring, smoothing, and cooling on the rheological properties of nonfat yogurts stirred with a technical scale unit
Bibliographic record
Abstract
Few studies have considered the impact of unit operations during stirred yogurt manufacture because their operational sequence is difficult to replicate at the laboratory scale. The aim of this study was to investigate the individual and sequential effects of stirring in the yogurt vat, smoothing, and cooling on the rheological properties of yogurts, using a technical scale unit simulating some industrial conditions. The yogurts were prepared from a milk mixture that was standardized to contain 14% total solids, 0% fat, and 4% protein, and then homogenized, heated (94.5°C, 5 min), and inoculated at 41°C with the same thermophilic lactic starter. The operating parameters under investigation were 2 stirring durations in the yogurt vat (5 or 10 min), 2 cooling systems (plate or tubular heat exchanger), and 2 smoothing temperatures (38°C for smoothing before cooling; 20°C for smoothing after cooling). Sampling valves were installed at critical points on the technical scale unit so that the effect of each operation on the properties of stirred yogurt could be quantified individually. Syneresis, apparent viscosity, firmness, and consistency were analyzed after 1 d of storage at 4°C. In general, as the yogurts moved through the technical scale unit, the properties of the yogurts (evaluated after 1 d) changed: viscosity increased but syneresis, firmness, and consistency decreased. The individual effects of the operations showed that smoothing and cooling, compared with stirring duration, made the greatest contribution in terms of modifying yogurt properties. The stirring parameters (5 or 10 min) had similar effects on the yogurts. The use of a plate heat exchanger promoted a decrease in syneresis, whereas a tubular heat exchanger had a greater effect in terms of increasing firmness and consistency. The type of cooling system had no effect on stirred yogurt viscosity. Smoothing at 38°C had a greater effect on the increase in firmness, whereas smoothing at 20°C contributed more to a decrease in syneresis and increases in viscosity and consistency. This study confirms that each unit operation has a defined effect on the rheological properties of a nonfat stirred yogurt, which also depends on the operation sequence.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".