Stühmeier-Niehe Corinna, Lass Luca, Brocksieper Miriam, Chanos Panagiotis, Hertel Christian
Department of Biotechnology, German Institute of Technologies (DIL), Professor-von Klitzing Str. 7, 49610 Quakenbrück, Germany.
Elea Technology GmbH, Professor-von Klitzing Str. 9, 49610 Quakenbrück, Germany.
Foods. 2023 Jan 17;12(3):442. doi: 10.3390/foods12030442.
The aim of this study was to investigate the effect of pulsed electric field (PEF) pre-treatment of a dairy starter culture of subsp. LB186 and ST504 on the fermentation and final product characteristics of set-style yogurt. The effects of PEF treatment parameters, voltage (4-20 kV), pulse number (20-80 pulses), frequency (1-21 Hz), and pulse (5-8 µs) width on pH development, cell counts, and proteolytic activity, as well as on texture and degree of syneresis in yogurt were investigated by use of a two-level full factorial design. Pulse frequency and pulse width had a significant effect on the yogurt stiffness ( < 0.05) and the interaction of voltage and frequency had a significant effect on both stiffness and proteolytic activity ( < 0.05). Further experiments confirmed that pre-treatment of the dairy culture with specific PEF parameters immediately before addition to milk could accelerate fermentation of, increase stiffness of, and reduce syneresis in the final yogurt. This effect of the PEF-pre-treated culture was partially retained even after flash-freezing and 14 days of storage of the culture at -20 °C. The effects were attributed to responses to oxidative stress induced by the PEF pre-treatment.
本研究的目的是调查脉冲电场（PEF）预处理嗜热链球菌亚种LB186和嗜热栖热菌ST504的乳制品发酵剂对凝固型酸奶发酵及最终产品特性的影响。采用二级全因子设计，研究了PEF处理参数，即电压（4 - 20 kV）、脉冲数（20 - 80个脉冲）、频率（1 - 21 Hz）和脉冲宽度（5 - 8 μs）对pH值变化、细胞计数、蛋白水解活性的影响，以及对酸奶质地和脱水收缩程度的影响。脉冲频率和脉冲宽度对酸奶硬度有显著影响（P < 0.05），电压和频率的交互作用对硬度和蛋白水解活性均有显著影响（P < 0.05）。进一步实验证实，在将乳制品发酵剂添加到牛奶之前，立即用特定的PEF参数进行预处理，可以加速最终酸奶的发酵，增加其硬度，并减少脱水收缩。即使在将经PEF预处理的发酵剂速冻并在-20°C下储存14天后，这种效果仍能部分保留。这些影响归因于对PEF预处理诱导的氧化应激的反应。
