Partition of five aroma compounds between air and skim milk, anhydrous milk fat or full-fat cream

Abstract

-The present study deals with the physicochemical interactions between aroma compounds and various dairy media used as models of complex food matrices, as well as the consequences of the interactions on aroma partitioning between the air and matrix. Five aroma compounds were investigated: amyl and isoamyl acetate, ethyl pentanoate, hexanal and t-2-hexenal. Skim milk, anhydrous milk fat and full-fat cream were chosen as dairy media, while water was used as a reference medium. Apparent partition coefficients of the five aromas were determined between the air and media between 30 and 80 °C by static headspace-gas chromatography. Partition coefficients over full-fat cream were also calculated from partition coefficients over skim milk and anhydrous milk fat. Compared with water, a significant retention of t-2-hexenal was observed in skim milk (nearly 90% whatever the temperature), whereas the retention of the other aromas varied from 6% for isoamyl acetate to 40% for hexanal in skim milk. Hydrophobic interactions were responsible for the retention of esters, whereas covalent binding of t-2-hexenal by dairy proteins was probably involved. The volatility of the 5 aromas was drastically reduced over anhydrous milk fat, because of their hydrophobic nature (log P > 1). There were discrepancies between calculated and measured partition coefficients over full-fat cream, which depended on aroma compounds and temperature. Measured and calculated ethyl pentanoate retentions were similar whatever the temperature. For isoamyl acetate, hexanal and, to a lesser extent, t-2-hexenal, aroma retention was greater than expected. The reverse phenomenon was observed with amyl acetate. The so-called "enthalpy of affinity" was calculated from the variation of the partition coefficient with temperature. This parameter allowed an overview of the relative importance of aroma compounds-matrices interactions. Anhydrous milk fat

Effect of feed pH and non-volatile dairy components on flavour concentration by pervaporation

“…7 shows that this was true for the esters and ketones in this study: at higher fat levels, when relatively less of each compound was in the aqueous phase and more in the fat phase of the feed, the headspace mole fractions were lower. A similar finding was reported by Meynier et al (2003), who measured the volatility of five esters and aldehydes in water, skim milk, anhydrous milk fat and cream. They observed that air/cream partition coefficients were 94-99% lower than the air/water partition coefficients, indicating that the flavour compounds were less volatile in cream than in water.…”

“…Because flavour compound volatilities tend to be much lower in fat than in water (Landy et al, 1996;Meynier et al, 2003), the portion dissolved in the fat phase should not contribute significantly to the driving force. A comparison of Fig.…”

Aroma release and chewing activity during eating different model cheeses

“…The effect of fat melting point was significant in the case of subjects A and C and the effect of mixing speed was significant for subjects A and D. The effect of an increase in fat content, fat melting point and degree of emulsification, when significant, resulted in a reduction of aroma release. The effect of fat as an aroma release suppressor has been demonstrated in both, static and dynamic conditions (Meynier, Garillon, Lethuaut, & Genot, 2003;Weel et al, 2002). Using the lower mixing speed resulted in softer products with less rigid structure that allowed an easier release of aroma compounds.…”

Sweetness and aroma perceptions in dairy desserts varying in sucrose and aroma levels and in textural agent

“…Aroma concentration in the dessert was calculated from the initial accurate weighing. Aroma concentration in the air phase was measured by GC-headspace analyses with acquisition conditions adapted from Meynier, Garillon, Lethuaut, and Genot (2003) where partition coefficients of the four aroma compounds were measured in dairy media. The vials were equilibrated at 50 1C for one hour before analysis and the injected volume was 1500 mL.…”