We evaluate how perceptual discrimination depends on fat content for a range of liquid and semi-liquid foods. We also investigate the role played in fat discrimination by olfaction, vision and taste and how sensory results can be related to physicochemical characteristics. The food matrices under investigation were all made of a continuous water phase containing various amounts of fat (sunflower oil-inwater emulsions, flavored and unflavored milk, stirred yoghurt and emulsified white sauce). We find that the sensory fat discrimination varies strongly depending on the food and the tasting conditions. Here, the fat content of low viscosity samples could be reduced or increased by 50%, without significantly impacting fat perception. However, the fat difference threshold is much lower for high viscosity samples. We also found that our sensory results are not related to the rheological properties. However, tribology data on stirred yoghurts were found to be valuable instrumental parameters for the study of the interactions between food composition and sensory perception.

In an industrial context focusing on fat reduction in biscuits, the temporal dominance of sensations (TDS) evaluation method was applied to six biscuits differing in fat level (full, 30% fat reduced, or 50% fat reduced) and fat quality (butter or margarine). A list of 10 attributes for texture, taste, and olfactive modalities was produced based on a previously undertaken sensory profile (data not shown). TDS curves, pairwise comparison curves, and sensory trajectories were valuable tools for identifying the main dominance differences according to fat levels. The 50% fat‐reduced products were clearly discriminated from full‐fat products. Inclusion of the three sensory modalities within the attribute list was anticipated as a complex task. Nevertheless, specific sensory phases were identified and key flavor dominances defined. Dynamic sensory profiling opens the door to the creation of tailor‐made flavor compositions that compensate for part of the identified olfactive and taste losses. Practical Applications This work highlights the added value of considering several sensory modalities: taste, olfaction, and texture, at the same time, into TDS study. The definition of specific sensory phases over the food consumption will guide products developers to create specific flavors or combinations of flavors and taste compounds to cover the sensory gap observed in fat, sugar, or salt reduction context.

Treatment of cyclohexadecanone (1g; with I2 (2.2 mol‐euqiv.) and KOH in MeOH) furnished the unsaturated (Z)‐ester 2g in 83% yield, via a stereospecific Favorskii rearrangement (Scheme 1). Further treatment with 3‐chloroperbenzoic acid (m‐CPBA) afforded the unreported epoxy ester 3g (88% yield), which was cleaved in 33% yield to Exaltone® (=cyclopentadecanone; 1f) with NaOH in MeOH/H2O and then HCl at 65°. This methodology was similarly extended to higher (C17) and lower (C15 to C11) cyclic ketone analogues, as well as regioselectively to (−)‐(R)‐muscone (5c) and homomuscone (5f) (Scheme 2). Olfactive properties of the corresponding macrocyclic 1‐oxaspiro[2,n]alkanes and ‐alkenes 4 and 8, resulting from a CoreyChaykovsky oxiranylation, are also presented.

To complete our panorama in structure-activity relationships (SARs) of sandalwood-like alcohols derived from analogues of a-campholenal (= (1R)-2,2,3-trimethylcyclopent-3-ene-1-acetaldehyde), we isomerized the epoxy-isopropyl-apopinene (À)-2d to the corresponding unreported a-campholenal analogue (+)-4d (Scheme 1). Derived from the known 3-demethyl-a-campholenal (+)-4a, we prepared the saturated analogue (+)-5a by hydrogenation, while the heterocyclic aldehyde (+)-5b was obtained via a Bayer-Villiger reaction from the known methyl ketone (+)-6. Oxidative hydroboration of the known acampholenal acetal (À)-8b allowed, after subsequent oxidation of alcohol (+)-9b to ketone (+)-10, and appropriate alkyl Grignard reaction, access to the 3,4-disubstituted analogues (+)-4f,g following dehydration and deprotection. (Scheme 2). Epoxidation of either (+)-4b or its methyl ketone (+)-4h, afforded stereoselectively the trans-epoxy derivatives 11a,b, while the minor cis-stereoisomer (+)-12a was isolated by chromatography (trans/cis of the epoxy moiety relative to the C 2 or C 3 side chain). Alternatively, the corresponding trans-epoxy alcohol or acetate 13a,b was obtained either by reduction/esterification from trans-epoxy aldehyde (+)-11a or by stereoselective epoxidation of the a-campholenol (+)-15a or of its acetate (À)-15b, respectively. Their cis-analogues were prepared starting from (+)-12a. Either (+)-4h or (À)-11b, was submitted to a Bayer-Villiger oxidation to afford acetate (À)-16a. Since isomerizations of (À)-16 lead preferentially to b-campholene isomers, we followed a known procedure for the isomerization of (À)-epoxyverbenone (À)-2e to the norcampholenal analogue (+)-19a. Reduction and subsequent protection afforded the silyl ether (À)-19c, which was stereoselectively hydroborated under oxidative condition to afford the secondary alcohol (+)-20c. Further oxidation and epimerization furnished the trans-ketone (À)-17a, a known intermediate of either (+)-b-necrodol (= (+)-(1S,3S)-2,2,3-trimethyl-4methylenecyclopentanemethanol; 17c) or (+)-(Z)-lancifolol (= (1S,3R,4Z)-2,2,3-trimethyl-4-(4-methylpent-3-enylidene)cyclopentanemethanol). Finally, hydrogenation of (+)-4b gave the saturated cis-aldehyde (+)-21, readily reduced to its corresponding alcohol (+)-22a. Similarly, hydrogenation of b-campholenol (= 2,3,3-trimethylcyclopent-1-ene-1-ethanol) gave access via the cis-alcohol rac-23a, to the cis-aldehyde rac-24.