2-acetyl-1-pyrroline …is regarded as the most important aroma compound in fragrant rice… (it) is described as ‘pandan’, ‘popcorn’ or ‘nutty’ and contributes to the “roasted aroma” of cooked beef and crusts of wheat and rye breads
2AP is produced by the rice plant, and is detected in the majority of plant tissues (Sakthivelet. al, 2009; Sood & Siddiq, 1978; Yoshihashi, Huong, & Inatomi, 2002). Although some 2-AP in rice is produced during cooking, the majority of 2-AP biosynthesised in the rice plant itself and is detected in the majority of plant tissues (Sakthivelet. al, 2009; Sood & Siddiq, 1978; Yoshihashi, Huong, & Inatomi, 2002). It is formed in all parts of the plant (stems, leaves and grains) except roots (Buttery et al., 1983; Yoshihashi et al., 2002a, b) during growth in paddy fields. So the aroma can be detected in both the grains as well as the leaf tissue
Despite it’s attractive and desirably aromatics, 2AP is unfortunately unstable and degrades rapidly. Pure 2AP will degrade within 10 min at room temperature (Fang & Cadwallader, 2014). Loss of 2-AP in stored foods could be due to complexation, decomposition, diffusion to the environment and generation of other compounds (Adams & De Kimpe, 2006). After only 3 months of storage, 2-AP level can be reduced by 40–50% in a variety of different rices (Widjaja et al., 1996a). Another study aimed to compare the effect of different drying methods and storage time on 2-AP reduction in fragrant rice (Wongpornchai et al., 2004) 2-AP concentration in 10 months stored rice was only 25% of freshly dried rice and it was shown in a concentration– storage time curve that a significant decrease occurred at the beginning of storage.
The concentration of 2AP is reduced over the course of months in regular storage and packaging, which leads to connoisseurs to seek out the freshly harvested new crop jasmine rice. Thus it is important to try to preserve the 2AP content of rice, and also to consume as close to harvest as possible to maximise the aromatics and flavour.
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