Table 2.
Fermentation parameters of low alcohol wines produced by repeated batch fermentations at 5–30 °C using wet or freeze-dried kefir culture.
| Nature of Kefir Culture | °C | N° | Fermentation Time (h) |
Ethanol Concentration (% vol) | Glycerol (g/L) |
Residual Sugars (g/L) |
Ethanol Productivity [g/(Ld)] | Ethanol Production Yield | Conversion (%) |
|||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| State of the Cells: | W | Fd | W | Fd | W | Fd | W | Fd | W | Fd | W | Fd | W | Fd | ||
| Free cells | 30 | 1–3 | 154–165 | 110–240 | 9.6–10.5 | 6.3–9.0 | 5.7–6.4 | 5.0–7.1 | 2.0–10.5 | 3.7–5.5 | 11.0–12.8 | 7.0–15.5 | 0.45–0.47 | 0.30–0.43 | 94.1–98.9 | 96.8–97.8 |
| 20 | 4–8 | 155–250 | 90–135 | 10.2–10.5 | 7.4–10.1 | 6.4–7.4 | 4.4–9.6 | 1.7–6.6 | 2.5–7.7 | 8.0–12.9 | 10.8–16.4 | 0.47–0.48 | 0.35–0.46 | 96.3–99.0 | 95.5–98.5 | |
| 5 | 9–11 | 950–1078 | 1500–4000 | 7.3–10.2 | 7.8–9.0 | 5.1–6.2 | 5.7–7.6 | 7.7–15.5 | 1.9–5.0 | 1.3–1.9 | 0.4–1.0 | 0.36–0.47 | 0.37–0.43 | 91.3–95.7 | 97.1–98.9 | |
| Immob. cells on apple pieces | 30 | 1–3 | 50–70 | 72–120 | 7.1–9.5 | 5.9–8.2 | 4.7–6.8 | 3.0–5.9 | 2.8–5.2 | 2.0–4.4 | 19.4–30.0 | 9.3–20.0 | 0.33–0.45 | 0.28–0.39 | 96.9–98.3 | 97.4–98.8 |
| 20 | 4–8 | 94–115 | 72–100 | 7.3–10.5 | 7.6–10.3 | 5.8–7.6 | 6.7–9.9 | 3.4–9.1 | 1.8–5.6 | 14.7–21.4 | 16.0–23.2 | 0.36–0.49 | 0.36–0.47 | 94.6–98.0 | 96.8–98.9 | |
| 5 | 9–11 | 940–1220 | 816–1300 | 6.6–8.3 | 7.7–10.5 | 4.3–6.0 | 6.5–8.4 | 8.1–10.3 | 1.9–8.3 | 1.0–1.4 | 1.4–2.1 | 0.33–0.40 | 0.36–0.47 | 94.0–95.2 | 95.1–98.9 | |
| Immob. cells on DCM | 30 | 1–3 | 48–140 | 70–90 | 7.0–10.0 | 7.2–9.0 | 5.7–7.3 | 5.8–7.8 | 2.2–7.4 | 3.3–4.8 | 9.5–39.5 | 16.9–24.4 | 0.33–0.46 | 0.34–0.43 | 95.6–98.7 | 97.2–98.1 |
| 20 | 4–8 | 53–105 | 72–100 | 8.2–10.3 | 8.6–10.0 | 7.1–8.6 | 6.6–8.8 | 3.2–9.7 | 2.0–9.7 | 18.7–31.6 | 16.5–22.6 | 0.40–0.47 | 0.42–0.47 | 94.3–98.2 | 94.3–98.8 | |
| 5 | 9–11 | 590–740 | 480–650 | 7.1–9.6 | 7.0–9.1 | 6.2–8.4 | 5.6–8.3 | 6.3–10.5 | 1.6–2.2 | 1.9–2.5 | 2.2–2.8 | 0.35–0.46 | 0.33–0.43 | 93.8–96.3 | 98.7–99.1 | |
| Immob. cells on grape skins | 30 | 1–3 | 72–94 | 120–156 | 5.9–8.8 | 9.2–9.9 | 5.5–7.9 | 6.7–7.6 | 5.3–7.2 | 5.1–6.4 | 15.6–20.8 | 11.2–14.7 | 0.29–0.42 | 0.44–0.47 | 95.8–96.9 | 96.2–97.0 |
| 20 | 4–8 | 75–120 | 90–175 | 7.1–8.7 | 9.7–10.5 | 6.2–9.1 | 7.7–10.8 | 4.1–7.6 | 1.2–8.1 | 13.7–19.1 | 10.8–21.1 | 0.35–0.41 | 0.46–0.47 | 95.5–97.6 | 95.4–99.3 | |
| 5 | 9–11 | 670–780 | 740–910 | 4.5–7.3 | 10.0–10.5 | 4.2–5.6 | 9.1–10.2 | 8.3–11.8 | 1.4–5.0 | 1.3–1.9 | 2.2–2.6 | 0.22–0.36 | 0.46–0.47 | 93.0–95.1 | 97.2–99.2 | |
| F-values | ||||||||||||||||
| State of the cells | 7.44 ** | 2.59 | 14.71 ** | 33.51 ** | 4.61 * | 1.73 | 33.4 ** | |||||||||
| Nature of kefir culture | 15.77 ** | 2.76 * | 6.50 ** | 0.46 | 13.60 ** | 2.17 | 0.4 | |||||||||
| Fermentation temperature | 154.32 ** | 7.96 ** | 11.38 ** | 3.85 * | 130.34 ** | 7.77 ** | 3.9 * | |||||||||
| All interactions | 7.49 ** | 0.55 | 2.02 | 0.81 | 1.46 | 0.68 | 0.8 | |||||||||
N°: Number of repeated fermentation batches; W: Wet cells, Fd: Freeze-dried cells; * p < 0.05, ** p < 0.01.