Abstract：
Concentration is a key determinant in the overall positive impact of terpenes on milk and cheese aroma; additionally, route of intake may affect the achievable concentrations of dietary terpenes in milk and cheese. In this study, we explored the possibility that the amount of the monoterpene limonene transferred to sheep milk and its corresponding cheese could differ depending on the route of intake and that the aroma profile of these products could also differ. To this aim, 12 lactating dairy ewes were repeatedly exposed to limonene by the oral or respiratory route during a 48-h test period, according to a 3 × 3 Latin square experimental design. Limonene content was measured in individual and bulk milk samples, in 1-d-old and 15-d-old Caciotta cheese obtained from that milk, in the related whey and curd, and in the air inhaled by the ewes in the respiratory treatment group (to obtain an estimate of the dose actually supplied by this route). Bulk milk and fresh (1-d-old) cheese underwent sensory analysis by ortho-olfactory evaluation. Both intake routes demonstrated transfer of limonene to milk, but the respiratory route transferred limonene with greater efficiency than the oral route. Moreover, according to the protocol used in this study, a short period of respiratory exposure induced a slightly higher limonene content in milk compared with oral exposure. As to the fate of limonene during cheesemaking, an important part of it was lost into the whey, perhaps through volatilization. The differences between milk and cheese tended to dissipate in curd and fresh cheese and disappeared completely after 15 d of ripening. Finally, it was possible to distinguish between the 2 routes of limonene intake using sensory analysis, even though no direct relationship was identified between the different aroma profiles of milks and cheeses from the oral and respiratory groups and their respective limonene contents. Overall, our results expand current knowledge on the biological pathways of terpene transfer from feed to sheep milk and cheese, as well as on the role played by terpenes in the formation of aroma in these products. Our observations may contribute to future development of strategies for external control and better standardization of the presence of odor compounds in milk and cheese from dairy ruminants.
摘要：
浓度是萜烯对牛奶和奶酪香气总体积极影响的关键决定因素;此外，摄入途径可能会影响牛奶和奶酪中膳食萜烯的可达到浓度。在这项研究中,我们探索了转移到羊奶及其相应奶酪中的单萜柠檬烯的量可能因摄入途径而异，并且这些产品的香气特征也可能不同。为了这个目标,在48小时的测试期间，12只泌乳母羊通过口服或呼吸途径反复暴露于柠檬烯，根据3×3拉丁方实验设计。在个体和散装牛奶样品中测量柠檬烯含量，从该牛奶中获得的1d和15d的Caciotta奶酪，在相关的乳清和凝乳中，和呼吸治疗组中母羊吸入的空气中（以获得该途径实际提供的剂量的估计值）。通过原位嗅觉评估对散装牛奶和新鲜（1-d-old）奶酪进行了感官分析。两种摄入途径都表明柠檬烯转移到牛奶中，但是呼吸途径传递柠檬烯的效率高于口服途径。此外，根据这项研究中使用的方案，与口服暴露相比，短时间的呼吸道暴露会导致牛奶中的柠檬烯含量略高。至于柠檬烯在奶酪制作过程中的命运，它的一个重要部分迷失在乳清中，也许是通过挥发。牛奶和奶酪之间的差异倾向于在凝乳和新鲜奶酪中消散，并在成熟15d后完全消失。最后,使用感官分析可以区分柠檬烯摄入的两种途径，即使口腔和呼吸道组的牛奶和奶酪的不同香气特征与其各自的柠檬烯含量之间没有直接关系。总的来说,我们的研究结果扩展了目前关于萜烯从饲料转移到羊奶和奶酪的生物学途径的知识，以及萜烯在这些产品香气形成中所起的作用。我们的观察结果可能有助于未来制定外部控制策略，并更好地标准化来自反刍动物的牛奶和奶酪中的气味化合物。
