Volatile organic compounds released by enzymatic reactions in raw nonpareil almond kernel

Abstract

Benzaldehyde is well recognized as the predominant aroma in bitter almond (Prunus dulcis var amara) and is released from amygdalin upon enzymatic hydrolysis followed by a loss of hydrogen cyanide. Sweet almond (Prunus dulcis Mill. D.A. Webb) has a sweeter, nuttier aroma than the bitter variety. While benzaldehyde is detected in raw sweet almond, it is not the predominant compound contributing to aroma due to the lower level of amygdalin. Although a variety of volatile organic compounds (VOCs) in sweet almond have been identified, the identity of VOCs due to enzymatic reactions in sweet almond has not been well documented. In this study, we investigated the VOCs released by enzymatic reactions in raw nonpareil (sweet) almond kernel samples and identified several alcohols such as isobutanol, 2-pentanol, 3-methylbutanol, 3-methyl-3-buten-1-ol, and 3-methyl-2-buten-1-ol as the major enzyme-released VOCs. Their released amounts were greater in the sweet almond kernels than in the bitter ones analyzed, suggesting that these alcohols may contribute to the characteristic aroma in the raw sweet almond.