Sensory evaluation of the odour of a sunflower oil emulsion throughout oxidation

Abstract

Sensory evaluation of the odour of a sunflower oil emulsion throughout oxidationOxidation of unsaturated fatty acids is responsible for off-flavours, often described as rancid flavours. This study was aimed at describing the evolution of the odour of a sunflower oil-in-water emulsion during oxidation at 50 7C in the dark. Appearance of an odour and occurrence of oxidation were first tested for at short-time aging (0-4 h) by the triangle test and measurements of oxygen consumption, respectively. The odour of the emulsion oxidised for up to 240 h was then characterised by sensory profile, while volatiles issued from lipid oxidation were analysed in the headspace by SPME. From 1 h of aging, while oxygen consumption remained weak, a significant change of the odour was detected by the panel. Up to 21 volatile compounds were identified in the headspace of long-time-oxidised emulsions. Beyond the rancid attribute, seven attributes were chosen to describe the odour of oxidised emulsions, four of which referring to solutions of a single volatile oxidation compound. The contribution of the fresh oil attribute, initially dominant, was progressively overtaken from 6 to 24 h of aging by the deep-fried attribute, which later declined in favour of the painty attribute, predominant after 100 h. Evolution of intensity scores and contribution to odour profiles of attributes could not be easily related to one reference volatile compound or another, confirming the complex relationship between the generated volatile compounds and the perceived odour.

Meat Processing and Colon Carcinogenesis: Cooked, Nitrite-Treated, and Oxidized High-Heme Cured Meat Promotes Mucin-Depleted Foci in Rats

“…Hexanal was selected as a specific and reliable marker of secondary products of lipid oxidation in meat products. It was analyzed by gas chromatography of the volatile compounds sampled in the headspace of the samples dispersed in phosphate buffer equilibrated at 37°C, with a solid-phase micro-extraction fiber (29,30). Fiber coated with polydimethylsiloxane (PDMS; 100-μm film thickness; Supelco) or carboxen/PDMS (75-μm film thickness; Supelco) was used according to the required sensitivity, which depended on the sample and its oxidation level.…”

“…The solid-phase micro-extraction fiber was then exposed in the headspace for 5 minutes at 37 ± 1°C. Gas chromatography analysis was then done as described by Villiere et al (30). Peak areas of hexanal were integrated, and the volatile concentrations in the samples (pg/g) were calculated from linear regressions that included the area measured with the sample with no addition of known amount of hexanal (six concentrations per sample).…”

Deep Frying Performance of Enzymatically Synthesized Palm-Based Medium- and Long-Chain Triacylglycerols (MLCT) Oil Blends

“…The onset of rancidity as determined by human sensory evaluation is the ultimate test to determine the oxidative status of oils and fats. Only sensory analysis can detect offflavor formation by oxidative and non-oxidative degradation reactions as a consequence of the low odor thresholds of volatile products of lipid oxidation (Villière et al 2007). Sensory analysis of frying oil and fried-food quality may be conducted by analytical descriptive method using trained and experienced panelists or hedonic scale sensory attributes using untrained panelists (Melton 1996).…”

Lipid Oxidation in Oil‐in‐Water Emulsions: Involvement of the Interfacial Layer

“…Lipid oxidation has a deleterious effect on the technological, sensory, and nutritional qualities of food (Pokorny ; Frankel ). The reaction generates odorant compounds characterized by low detection thresholds and generally unpleasant perceptions, which damages the sensory quality of the products (Grosch ; Frankel ; Villière and others ). Lipid oxidation also causes a loss of components of nutritional interest, and leads to the formation of free radicals and potentially toxic compounds (Ursini and others ; Kanazawa and others ; Riemersma ; Liu and others ; Petersen and Doorn ; Turner and others ; Long and others ; Eder and Ringseis ; Serini and others ; Awada and others ).…”