Flavor Volatiles of Rice During Cooking Analyzed by Modified Headspace SPME/GC‐MS

Abstract

The flavor volatiles in three Japanese rice cultivars, Nihonbare, Koshihikari, and Akitakomachi, during cooking were directly extracted by using a modified headspace solid‐phase microextraction (SPME) method and analyzed by gas chromatography‐mass spectrometry (GC‐MS). A total of 46 components were identified, including aldehydes, ketones, alcohols, and heterocyclic compounds, as well as fatty acids and esters, phenolic compounds, hydrocarbons, etc. The amount of key odorant compounds increased with cooking, while the amount of low‐boiling volatiles decreased. The similarities and differences of the three rice cultivars were determined through a comparison of their volatile components. Nihonbare was characterized by a higher amount of indole but an absence of the chemical class of fatty acid esters. In contrast, both Koshihikari and Akitakomachi had a higher amount of 4‐vinylphenol and an abundance of those esters. Koshihikari and Akitakomachi were quite similar in regard to those flavor volatiles. Furthermore, the observations in the research may suggest that the volatile components at cooking stage (I) were the representatives of the flavor volatiles of uncooked rice, while the volatile constituents at cooking stage (IV) were the representatives of the flavor volatiles of cooked rice.

Changes in volatile aroma compounds of organic fragrant rice during storage under different conditions

“…21 Direct extraction of volatile compounds of rice during cooking in an automatic rice cooker, using the SPME/GC/MS technique, revealed that 4-vinyl guaiacol was detected during the last 10 min of cooking and also during 30 min of warming in the cooker. 15 The latter results also indicated the thermally induced formation of this compound. A previous study reported an increase in 4-vinyl guaiacol in both hulled and milled rice samples stored in paper bags at 30…”

“…These volatiles have previously been reported as odour-active compounds of cooked black or white rice of several japonica and indica cultivars 11,12 and/or flavour molecular markers used to differentiate three Japanese rice cultivars. 15 Ten of these compounds have been identified as volatile lipid oxidation products 10,16,17 that may relate to off-flavour of rice samples. Storage time and temperature as well as type of packaging material apparently affected the relative amounts of isolated volatiles from the rice samples (Tables 3-5).…”

“…7,8,13,14 During the first 6 months of storage a significant reduction of 2-AP in hulled rice was shown from the samples packed in Nylon/LLDPE pouches and stored at ambient temperature (P ≤ 0.05). The retention of 2-AP was improved either by selecting the packaging with limited gas permeability (OPP/Al/LLDPE) or storing the sample at lower temperature (15 • C). The results agreed well with those from previous studies.…”

“…• C upon injection and was programmed at 2 (7), (8), (9) (10), (11) 1216 1213 (2) 2-Pentylfuran Floral, fruity, nutty, beany (7), (9) (10), (11), (12) 1281 1280 (3) Octanal Slightly fruity, citrus (7), (8), (9) (10), (11) 1344 1348 (4) 2-Acetyl-1-pyrroline Popcorn -(10), (11) 1405 1400 (5) Nonanal Citrus, floral, fruity (8), (9) (10), (11) 1454 1458 (6) 1-Octen-3-ol Mushroom (8) (10), (11), (12) 1496 1497 (3) Decanal Citrus, sweet, waxy, floral (8), (9) (10), (11) 1536 1542 (1) (E)-2-Nonenal Beany, cucumber, fatty, woody (7), (8), (9) (10), (11), (12) 1564 1567 (6) 12 and (12) Zeng et al 15 this study with those reported in the literature is shown in Table 2.…”

Characterization of Volatile Aroma Compounds from Red and Black Rice Bran

“…Rice bran, the outer brown layer that removed during the milling of brown rice, has been extensively studied, of which 4-vinylphenol was the main component having a characteristic unpleasant odor [2][3][4] . Many researchers have studied volatile compound in raw and cooked rice, 2-acetyl-1-pyrroline (2-AP; popcorn aroma) was reported as an important contributor to be the aroma characteristic of rice [5][6][7][8][9] . Straw of rice also reported on volatile components, palmitic acid was the most abundant component, followed by hexahydrofarnesyl acetone and phytol 10) .…”