To develop a ready-to-drink (RTD) milk coffee retaining the original coffee flavor, the effects of processing conditions during manufacture on retronasal-arma (RA) compounds from the milk coffee were investigated by gas chromatography-mass spectrometry using an RA simulator (RAS). Thirteen of 46 detected compounds in the RAS effluent (RAS compounds) decreased significantly following pH adjustment of coffee (from pH 5.1 to 6.8) and 5 compounds increased. RAS compounds from coffee tended to decrease through the pH adjustment and subsequent sterilization. Significantly higher amounts of 13 RAS compounds were released from the milk coffee produced using a blending-after-sterilization (BAS) process without the pH adjustment than from that using a blending-before-sterilization (BBS) process with the pH adjustment. In BAS-processed milk coffee, significantly lower amounts of 8 high-volatility compounds and 1H-pyrrole were released from coffee containing infusion-sterilized (INF) milk than from coffee containing plate-sterilized (PLT) milk, whereas 3 low-volatility compounds were released significantly more from coffee using PLT milk. Principal component analysis revealed that the effect of the manufacturing process (BAS, BBS, or homemade (blending unsterilized coffee without pH adjustment with sterilized milk)) on milk coffee volatiles was larger than that of the sterilization method (INF or PLT) for milk, and that the sterilization method could result in different RAS volatile characteristics in BAS and homemade processes. In conclusion, a BAS process was found to be superior to a BBS process for the manufacture of an RTD milk coffee that retains volatile characteristics similar to that of a homemade milk coffee. PRACTICAL APPLICATION Ready-to-drink (RTD) milk coffee manufactured using the conventional blending-before-sterilization process does not retain its original coffee flavor due to pH adjustment of the coffee during the process. The new blending-after-sterilization (BAS) process enabled the production of RTD milk coffee whose volatiles are closer to that of homemade milk coffee, as demonstrated by the results of RAS-GC-MS analysis. The BAS process has already been applied to the manufacture of RTD milk coffees in Japan.

中文翻译：

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制造过程中加工条件对牛奶咖啡饮料中鼻后香气化合物的影响

为了开发一种保留原始咖啡风味的即饮 (RTD) 牛奶咖啡，使用 RA 模拟器通过气相色谱-质谱法研究了制造过程中加工条件对牛奶咖啡中的鼻后臂 (RA) 化合物的影响(RAS)。在调整咖啡的 pH 值（从 pH 5.1 到 6.8）后，在 RAS 流出物中检测到的 46 种化合物中有 13 种（RAS 化合物）显着减少，5 种化合物增加。咖啡中的 RAS 化合物往往会通过调节 pH 值和随后的灭菌而减少。与使用带有 pH 调节的灭菌前混合 (BBS) 工艺相比，使用灭菌后混合 (BAS) 工艺生产的牛奶咖啡中释放的 13 种 RAS 化合物的量显着更高。在BAS加工的牛奶咖啡中，含有浸泡消毒 (INF) 牛奶的咖啡中释放的 8 种高挥发性化合物和 1H-吡咯的量明显低于含有平板消毒 (PLT) 牛奶的咖啡，而使用使用咖啡的咖啡中释放的 3 种低挥发性化合物明显更多PLT 牛奶。主成分分析表明，制造过程（BAS、BBS或自制（将未经pH调节的未灭菌咖啡与灭菌牛奶混合）对牛奶咖啡挥发物的影响大于牛奶的灭菌方法（INF或PLT），并且灭菌方法可能导致BAS和自制工艺中不同的RAS挥发性特征。综上所述，发现 BAS 工艺优于 BBS 工艺来制造 RTD 奶咖啡，该工艺保留了与自制奶咖啡相似的挥发性特征。实际应用 由于在加工过程中调整了咖啡的 pH 值，使用传统的混合前灭菌工艺制造的即饮 (RTD) 牛奶咖啡不会保留其原始咖啡风味。RAS-GC-MS 分析结果表明，新的灭菌后混合 (BAS) 工艺能够生产出挥发性物质更接近于自制奶咖啡的即饮奶咖啡。BAS 工艺已在日本应用于生产即饮牛奶咖啡。实际应用 由于在加工过程中调整了咖啡的 pH 值，使用传统的混合前灭菌工艺制造的即饮 (RTD) 牛奶咖啡不会保留其原始咖啡风味。RAS-GC-MS 分析结果表明，新的灭菌后混合 (BAS) 工艺能够生产出挥发性物质更接近于自制奶咖啡的即饮奶咖啡。BAS 工艺已在日本应用于生产即饮牛奶咖啡。实际应用 由于在加工过程中调整了咖啡的 pH 值，使用传统的混合前灭菌工艺制造的即饮 (RTD) 牛奶咖啡不会保留其原始咖啡风味。RAS-GC-MS 分析结果表明，新的灭菌后混合 (BAS) 工艺能够生产出挥发性物质更接近于自制奶咖啡的即饮奶咖啡。BAS 工艺已在日本应用于生产即饮牛奶咖啡。