milk or oat drink addition
process / process-milk-addition
牛乳・オーツ飲料の添加
Adding cow’s milk or an oat beverage to coffee. It changes not only bitterness and aroma as perceived in the mouth but also the composition of volatile compounds released from the cup.
Photographs (captions in Japanese)
濾過式コーヒーにコンデンスミルク（Bärenmarke ブランド）を注いでいる場面。コーヒーへ牛乳（または乳製品飲料）を加える工程の実施場面。
写っているもの: 該当なし（コーヒーへの乳製品添加という工程）部位・状態: コンデンスミルクをコーヒーへ注いでいる場面
写真: Superbass／ CC BY-SA 4.0／ 原画像／ 台帳の原画像
写真の範囲と来歴
被写体の確認: 原典の記載による同定。
掲載画像: Wikimedia Commons の原寸ファイルを sips で長辺2400pxに縮小。苦味研究所では切り抜き・色調変更なし（リサイズのみ）。 表示用には幅1200px上限のWebPを配信し、台帳の原画像は上のリンクから確認できます。
On this page (6 sections)
Reading the bitterness
Adding cow’s milk or an oat beverage to coffee affects not only perceived bitterness and aroma but also which sensations dominate over time. A TDS comparison (a method in which participants select the most salient sensation at each moment) of medium- and dark-roasted Arabica coffee mixed at 70% coffee and 30% milk or oat beverage found a significant decrease in the proportion of responses in which bitterness was considered dominant at several time points. TDS does not measure the intensity of bitterness itself, however, and the separate contributions of milk aroma, mouthfeel, and other factors were not isolated.
By contrast, the amount of aroma compounds released retronasally did not change in the same way as perception. A study that simultaneously measured TDS and volatiles in exhaled breath (PTR-ToF-MS) for the same samples found that adding cow’s milk or an oat beverage substantially changed perception but did not systematically reduce the release of coffee-derived volatile compounds. Changes in perception and in the amount of compounds reaching the nose do not necessarily move in the same direction.
Sources for this overview
Effects of Roasting Level and Milk Addition on In Vivo Aroma Release and Perception of Coffee
Checked for this overview: Confirmed a decrease in bitterness dominance in TDS and the method’s limitations. / Confirmed the finding that changes in perception and volatile release did not align.
Follow the connections
milk or oat drink addition →can reduce the temporal dom…→ bitterness →can be measured separately …→ astringency
milk or oat drink addition →can decrease→ astringency →is not synonymous with→ bitterness
Hypotheses and recipe candidates for this entry are on the Japanese page.
Structured claims — open a section to read each claim's confidence, evidence and limits
Sensory (3)
Scope: Temporal Dominance of Sensations (TDS) with 30% milk or oat drink added to medium- and dark-roast coffee
Note: The dominance rate of bitterness dropped in several time windows, including the early period. This does not assert intensity reduction, removal of taste substances, or a mechanism attributable solely to fat or protein.
Show data
process-milk-addition —can_reduce_temporal_dominance_of→ sensation-bitterScope: Simultaneous TDS and PTR-ToF-MS measurement in the same coffee test
Note: Adding milk strongly changed perception, but it did not systematically lower the release of coffee-derived volatile compounds.
Show data
process-milk-addition —does_not_reliably_track→ "A perceived decrease in coffee-derived flavor and a uniform decrease in retronasal volatile release"Scope: Laboratory conditions in which milk was added to an aqueous EGCG (gallated catechin) solution, using an oral-tribology system modeled on the salivary film.
Note: In the same experiment, milk instead substantially reduced the lubricity of the salivary lubricating film; relief of perceived astringency therefore cannot be explained by a decrease in the coefficient of friction alone. This was a result in an aqueous EGCG model system, not an experiment using a green-tea infusion or an actual matcha latte. The existing process-milk-addition entry describes adding cow’s milk or oat beverage to coffee; this claim has separate scope_text because it concerns tea catechins in a different context.
Show data
process-milk-addition —can_decrease→ sensation-astringent