ABSTRACT The study investigated the production of volatile organic compounds during the fermentation of maize containing 26.8% dry matter (DM). Forage was ensiled without additive or treated with 2 ml/kg of a chemical silage additive (SA) containing per litre 257 g sodium benzoate, 134 g potassium sorbate and 57 g ammonium propionate, and either sealed immediately or with a delay of 24 h. During the fermentation process, DM-losses, fermentation pattern (including ethyl lactate [EL] and ethyl acetate [EA]) and yeast numbers were determined. Delayed sealing and no SA resulted in highest DM losses with significant interactions between sealing time (ST) and SA on all sampling days (p < 0.001). The effects on organic acid production were variable depending on storage length. Ethanol production was affected by ST and SA, but promptly sealed silage treated with SA had consistently the lowest concentrations. Higher ethanol content during fermentation was associated with higher DM losses, as reflected by a strongly linear, positive relationship (R2 = 0.70, p < 0.001). Compared with promptly sealed silage, the counts of yeasts were higher after delayed sealing during the first 7 d of storage (p < 0.001). Moreover, SA reduced yeast numbers compared with untreated silage (p < 0.01). EL concentrations increased throughout storage, whereas EA acetate accumulation was very rapid and intense already during the early stages of fermentation and peaked on d 34. The differences in concentrations and accumulation pattern between EL and EA, especially during the early fermentation phases, make evident that their synthesis was facilitated by different pathways and reactions, respectively.

中文翻译：

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玉米发酵过程中挥发性有机化合物的形成受密封时间和青贮添加剂使用的影响

摘要 本研究调查了含有 26.8% 干物质 (DM) 的玉米发酵过程中挥发性有机化合物的产生。青贮饲料不加添加剂或用 2 ml/kg 的化学青贮添加剂 (SA) 处理，每升含有 257 g 苯甲酸钠、134 g 山梨酸钾和 57 g 丙酸铵，并立即密封或延迟 24 小时。在发酵过程中，测定了 DM 损失、发酵模式（包括乳酸乙酯 [EL] 和乙酸乙酯 [EA]）和酵母数量。延迟密封和无 SA 导致最高 DM 损失，所有采样日的密封时间 (ST) 和 SA 之间存在显着相互作用（p < 0.001）。对有机酸生产的影响因储存时间而异。乙醇生产受 ST 和 SA 影响，但是用 SA 处理的及时密封的青贮饲料的浓度始终最低。发酵过程中较高的乙醇含量与较高的 DM 损失相关，这反映在强烈的线性正相关关系中（R2 = 0.70，p < 0.001）。与立即密封的青贮饲料相比，在储存的前 7 天延迟密封后酵母菌的数量更高（p < 0.001）。此外，与未经处理的青贮饲料相比，SA 减少了酵母数量（p < 0.01）。EL 浓度在整个储存过程中增加，而 EA 醋酸盐的积累在发酵的早期阶段已经非常迅速和强烈，并在第 34 天达到峰值。 EL 和 EA 之间的浓度和积累模式的差异，尤其是在早期发酵阶段，