Does High Hydrostatic Pressure Affect Fruit Esters?

Abstract

The effect of high hydrostatic pressure on ester formation and hydrolysis was studied. Six esters and the corresponding carboxylic acids and alcohols were subjected to high-pressure treatments of 400 and 800MPa under three different pH conditions (namely, buffer solutions of pH 4, 6 and 8). The selected compounds were dissolved into buffer solutions, subjected to the pressure treatment and then extracted using dichloromethane. The analysis and quantification were carried out by gas chromatography with flame ionization as detector. High pressure appeared to have no effect on ester formation or hydrolysis under the investigated conditions. In all cases, a small decrease at the levels of carboxylic acids and esters was observed without any evidence of further reaction. This decrease, referred to as decomposition, depended on pressure and pH conditions. Ester decomposition was minimised when a high-pressure treatment of 400MPa in basic conditions (pH 8) was applied. Carboxylic acid decomposition was minimal in basic conditions and it was independent of the pressure applied.Keywords: strawberry; fruits; esters; high hydrostatic pressure; flavour Introduction High hydrostatic pressure (HHP) technology is a novel non-thermal food processing technology where foods are subjected to HHP, generally in the range of 100-600MPa, at or around room temperature (Mertens, 1995). In general, nowadays, food consumers have a high expectation of food quality. There is a strong demand for more 'natural' minimally processed, additive free foods and the reported beneficial and unique effects of high pressure appear to offer particular potential in these respects (Johnston, 1994).

Changes in Physicochemical Properties and Volatiles of Kiwifruit Pulp Beverage Treated with High Hydrostatic Pressure

“…Interestingly, this also would be part of the reason for the increase in the aldehydes content of treated samples. These results were similar to previous study about red plum puree and model systems containing fruit esters in buffer solution, in which the total arbitrary area units of alcohols and esters decreased respectively after HHP [45,50]. Among all treatments, the significantly higher alcohols concentration in pulp beverage treated at 400 MPa for 10 min suggested that this treatment could be positive to preserve alcohols in pulp beverage.…”

“…However, all treated samples were detected a remarkable reduction in the content of butyl acetate and butyl acetate were not detectable when samples treated by pressure greater than 400 MPa. The decrease in the content of butyl acetate after HHP treatment may be due to two reasons: (1) HHP activates or inactivates the enzymes that synthesize esters in fruit; (2) esters are hydrolyzed after HHP treatment [45]. Similarly, Yi et al [46] also reported the content of esters such as butyl acetate and isobutyl acetate in HHP-treated apple juice were lower than those of untreated juice.…”

Scalping of four aroma compounds by one common (LDPE) and one biosourced (PLA) packaging materials during high pressure treatments

“…However, their conclusions do not match and this subject is still under discussion. Lambadarios and Zabetakis (2002), in their extensive work about the stability of fruit esters at HP (conditions up to 22°C, 800 MPa, 15 min) reported slight to moderate decreases in ester concentration (between 0.1% and 18%) in buffer solution (pH 4, 6 and 8) depending on the ester and the treatment. However, no trend could be outlined for the intensity of the treatment and as in this study, they did not find any significant difference due to the pH of the solution.…”

Effect of thermal processing and storage condition on the flavour stability of spray-dried durian powder

“…The decline in ester compounds and formation of acids was probably due to hydrolysis of the fruit esters, which was likely to occur in the presence of aqueous solution. According to Lambadarious and Zabetakis (2002), nucleophilic substitution may occur when water molecules protonate the carboxylate ion in the ester molecules and subsequently form carboxylic acid. Such hydrolysis reaction is specifically favoured under low pH conditions between 4 and 6 in the fruit extract as the degree of protonation increased.…”