Carbon stable isotopic compositions of citric acid and malic acid in Japanese apricot liqueur decrease as the fruit ripens

Abstract

The carbon stable isotopic composition (δ¹³C) is often analyzed to quantify the addition of acidulants to Japanese apricot liqueur, but little is known about the variation in the δ¹³C values of the main organic acids arising from differences in the ripeness of Japanese apricots. We show that in Japanese apricot liqueur prepared using fruits at different stages of ripeness, the δ¹³C values of citric acid and malic acid ranged from -25.1‰ to -23.7‰ and from -22.3‰ to -19.7‰, respectively, and the δ¹³C values decreased as the fruit ripened. The average δ¹³C value of citric acid from liqueurs was 0.7‰ higher than that from fresh fruits, whereas the δ¹³C values of malic acid showed no isotope discrimination. The variation in δ¹³C values of the main organic acids in Japanese apricot liqueurs will help detect acidulant addition and control authenticity.

Keywords: Carbon stable isotope; Fruit liqueur; Fruit maturity; Japanese apricot; Organic acids.