Drivers of the In-Mouth Interaction between Lupin Protein Isolate and Selected Aroma Compounds: A Proton Transfer Reaction-Mass Spectrometry and Dynamic Time Intensity Analysis.

Plant proteins often carry off-notes, necessitating customized aroma addition. In vitro studies revealed protein-aroma binding, limiting release during consumption. This study employs in vivo nose space proton transfer reaction-time-of-flight-mass spectrometry and dynamic sensory evaluation (time intensity) to explore in-mouth interactions. In a lupin protein-based aqueous system, a sensory evaluation of a trained "green" attribute was conducted simultaneously with aroma release of hexanal, nonanal, and 2-nonanone during consumption. Results demonstrated that enlarging aldehyde chains and relocating the keto group reduced maximum perceived intensity (Imax_R) by 71.92 and 72.25%. Protein addition decreased Imax_R by 30.91, 36.84, and 72.41%, indicating protein-aroma interactions. Sensory findings revealed a perceived intensity that was lower upon protein addition. Aroma lingering correlated with aroma compounds' volatility and hydrophobicity, with nonanal exhibiting the longest persistence. In vitro mucin addition increased aroma binding four to 12-fold. Combining PTR-ToF-MS and time intensity elucidated crucial food behavior, i.e., protein-aroma interactions, that are pivotal for food design.

Comparison of the sensitivity of different aroma extraction techniques in combination with gas chromatography-mass spectrometry to detect minor aroma compounds in wine.

MicroVinification platforms are used for screening purposes to study aroma development in wine. These high-throughput methodologies require flavor analysis techniques that allow fast detection of a high number of aroma compounds which often appear in very low concentrations (µg/l). In this work, a selection of aroma extraction techniques in combination with gas chromatography-mass spectrometry (GC-MS) were evaluated to detect minor wine aroma compounds in low sample volume. The techniques evaluated were headspace (HS), headspace solid-phase dynamic extraction (HS-SPDE), headspace solid-phase microextraction (HS-SPME), direct immersion solid-phase microextraction (DI-SPME), stir bar sorptive extraction (SBSE) and monolithic material sorptive extraction (MMSE). DI-SPME showed the highest sensitivity as expressed by detection of the highest percentage of total aroma compounds at concentrations around 0.1 µg/l. SBSE and MMSE followed DI-SPME in terms of sensitivity. HS-SPME was less sensitive but considered sensitive enough for detection of most of the volatile compounds present in highly aromatic wines. Matrix effect was shown to strongly affect aroma extraction and therefore the sensitivity of the different extraction methods.

Application of the Olfactoscan method to study the ability of saturated aldehydes in masking the odor of methional.

A novel technology (Olfactoscan screening) was applied to screen for volatiles including saturated aldehydes that mask the perception of methional, an off-flavor commonly found in orange juice. For the screening experiment, methional odor pulses were generated by an olfactometer and, one by one, mixed with alternating odor compounds that were separated by gas chromatography from a model solution. Trained panelists evaluated the odor mixtures so formed for methional intensity. Methional perception was significantly suppressed if it was mixed with octanal (p < 0.05). Similar interactions were not observed between methional and other volatiles including hexanal. This observation suggests highly specific interaction between methional and octanal. Octanal-methional interactions were then tested in orange juice (quantitative descriptive analysis with expert panel, n = 10). At certain levels, octanal significantly suppressed methional-associated off-notes such as "musty", "decayed orange", and "potato" (p < 0.01). The overall flavor quality of the orange juice was significantly improved (p < 0.01). As it occurs naturally in orange juice, an enrichment of octanal during juice production is suggested to prevent a methional-induced loss of orange flavor quality.