Flavor release and stability comparison between nano and conventional emulsion as influenced by saliva

Flavour release and emulsion stability depend on volatile organic compounds' environmental conditions, food microstructure, and physicochemical properties. The effect of pH (3.5 vs 7.0) and saliva addition on stability and flavour release from nano and conventional emulsions was investigated using particle size, charge and Lumisizer measurments. Larger particle sizes were observed at lower pressures and in saliva-containing emulsions. At 1700 bar, nano-emulsions (below 150 nm) were created at pH 3.5 and 7.0 including saliva-containing emulsions. As was clear from the creaming velocity measurements, saliva addition decreased the emulsion stability by reducing particle charges and increased viscosity by more than 50%, especially when prepared at pH 3.5 closer to the isoelectric point of the used emulsifier β-lactoglobulin (pH 5.2). (5.2). Flavour release from emulsions was measured at equilibrium using a phase ratio variation to determine partition coefficients and dynamically using an electronic nose. Partition coefficients of the flavour compounds for most conditions were two to four times lower in emulsions prepared at pH 7.0 than at pH 3.5 and in emulsions without saliva. Emulsions prepared with higher pressures showed stronger flavor release rates, while additional salvia dropped the release rate for ethyl acetate at pH 3.5. The physicochemical properties of flavour compounds, saliva addition and pH of emulsions influenced flavour release more than homogenization pressures. The potential in using nano-emulsions in food applications an be attributed higher stability and enhanced flavor release

Correction: Involvement of phenoloxidase in browning during grinding of Tenebrio molitor larvae.

[This corrects the article DOI: 10.1371/journal.pone.0189685.]

Sips and intervals in the three sip size conditions.

<p> = administration of soup,  = instruction to swallow,  = pauses between sips,  = regulation of sips and pauses by subjects themselves. All three conditions were presented in a focused and distracted state, resulting in six conditions. In the small-sip condition, sips of 5 g were exposed in 2 s (from the start of soup administration until swallowing) in pulses of 5 s. In the large-sip condition, sips of 15 g were exposed in 6 s in pulses of 15 s. In the free-sip condition, subjects were free to start and stop the pump, thereby determining sip sizes and frequency by themselves. In the small-sip and large-sip conditions, subjects heard an auditory signal when they received the soup and a double auditory signal when they had to swallow.</p

Ad libitum intake in small-sip, large-sip and free-sip conditions (means+SD).

<p>Ad libitum intake was higher in the large-sip and free-sip conditions compared to the small-sip condition (P<0.001), and was higher in the distracted state than in the focused state (P = 0.003). Values on bars with different superscript letters are significantly different (P<0.05).</p

The reasons to terminate soup consumption.¹²

1<p>Values are means ± SDs. Values in rows with different superscript letters are significantly different (P<0.05).</p>2<p>The propositions were answered on a 5-point scale from “totally disagree” (1) to “completely agree” (5).</p>3<p>Significant main effects of sip size P<0.012.</p

Hunger (A) and fullness (B) ratings over time (9-point scale) (means).

<p>*After ad libitum intake (t = 0.5 h), hunger and fullness were affected by sip size (P<0.004), but not by distraction (P>0.31). * The ratings for hunger (A) were higher after the small-sip condition compared to the large-sip condition (P<0.003). The ratings for fullness (B) were lower after the small-sip condition compared to both the large-sip and the free-sip conditions (P<0.009).</p