---

Aroma in scented rice is considered as one of the major important quality traits preferred. Aroma in scented and basmati rice is due to 2-acetyl-1-pyrroline. The aroma development in rice grain is influenced by both genetic and environmental factors. Basmati rice, jasmine rice, Dehradun basmati, Katarni etc are some important types of fragrant rice. In this article, fragrance in rice and its measurement methods are described.  

Rice (Oryza Sativa L.) is a major food grain crop for two thirds of the population in world. In 2018-19 rice was grown in 44.5 million ha. area with production of 115.63 million tones. Worldwide India stands first in rice area and second in rice production after China Rice (including Basmati in India’s total cereal export. In Bihar, rice is cultivated an about 3.15 million ha. with the annual production of 6.6 million tones and productivity of 2095 kg/ha. Rice (Oryza Sativa L.) (21=24) is an autogamous, monocot crop belonging family poaceae and sub family oryzoidea. Aroma in rice is considered as one of the major important quality traits preferred, especially when taking consumer acceptance as a criterion. The popcorn like smell, soft texture and palatability of aromatic rice production in the market  consumer now-a-days have become more conscious of the quality of the rice than they consume and after prefer fragrance rice due to their characteristics and pleasant odor. Hence, to meet the growing demand of aromatic rice, breeders have an interest in improving the qualities of aromatic rice varieties along with its yield. After green revolution various compounds have been reported to be responsible for rice aroma in which is the compound 2-acetyl-1-pyrroline has been found to be a major compound responsible for the pleasant aroma in scented rice (Buttery et al. 1983). To distinguish between aromatic and non-aromatic rice varieties both at biochemical and molecular level is essential for maintaining the exquisite traits associated with this quality rice. The aroma development in rice grain is influenced by both genetic and environmental factors. Factors like day length, temperature, sunlight intensity and humidity and soil (like nutrient status, microbes population etc.)  might play an important role in aroma development.

 Methods of aroma test

 The conventional methods of plant selection for aroma are not easy because of the large effects of environment and very low odor threshold (0.1µ/kg) in water. The 2-acetyl 1-pyrroline (2AP) is found in all parts of plants of aromatic rice varieties except far line  in aromatic rice genotypes may explained by the presence of mutation resulting in a loss of function of the fgr gene product. The sensory tissues and grains after reacting them with solution of 1.7% (w/v) KoH are used for aroma test. However, this method is not reliable as the test can be personally biased due to saturation of nostril sense at different levels. The gas chromatography technique is a destructive, expensive and requires large amount of samples for aroma analysis in rice. Aroma is the most important quality parameter of all aromatic rice. The aromatic compound 2-acetyl-1-pyrolline (2AP) is generated in the entire aerial part and it can be detected even in the minute quality. The strength of aroma was scored in 0-3 scale where 0 denotes no aroma, 1 denotes slight aroma, 2 denotes moderate aroma and 3 denotes strong aroma. More than 100 volatile compounds have been identified in rice. A study has confirm the presence of 2-acetyl -1-pyroline (2AP) as the principal aroma compound in all the scented rice varieties. A recessive gene BADH2 encoding Betaine aldehyde dehydrogenase (BADH2) mapped on chromosome 8 of rice has been identified in genetic studies as the controlling gene for the level of 2-acetyl-1-pyrolline (2AP). The BADH2 also contributes to stress tolerance due to which the level of aroma contributing compound 2AP is higher in the plant exposed to stress. (Bradburry et al., 2009).

There are following varieties are preferred as aromatic rice varieties in eastern part of India.

Tab 1: Aromatic rice varieties in Eastern India

Aromatic varieties	Aroma	Breeding Technique
Basmati 370	Very strong	Pure-line Breeding
Adamchini	Average	Pure-line Breeding
Hansraj	Average	Pure-line breeding
Kalanamak	Strong	Pure-line breeding
Pusa basmati-1	Strong	Hybrid breeding

 Beside this Katarni, Ranga joha-1, Bindli, Dehradun, jeerabatti, Jasmine rice, Tulsimukul, etc. are some important aromatic varieties of rice. Gobindabhog, Radhatilak, Tulaipanji, Kalojira, Badshabhog, Dudheswar Seetabhog, Radhunipagal, Kalonunia, are some promising non-basmati landraces found in eastern India (Roy et al., 2017).

  Reference

 Bradbury LMT (2009) Identification of the gene responsible for fragrance in rice and chararacterisation of the enzyme transcribed from this gene and its homologs. PhD thesis, southern cross university, Lismore, Australia pp-11.

 

Buttery, R.G., Ling L.C., Juliano, B.O., & Turnbaugh J.G. (1983). Cooked rice aroma and 2-acetyl-1-pyrolline Journal of Agricultural and food chemistry, 31 (4), 823-826.

 

Roy, K., Mukherjee, A., Maity, A., Shubha, K., & Nag, A. (2018). Protecting Non-Basmati Indigenous Aromatic Rice Varieties of West Bengal, India Under Geographical Indication: A Critical Consideration. In The Role of Intellectual Property Rights in Agriculture and Allied Sciences (pp. 295-318). Apple Academic Press.

---

Fragrance and Aroma in Rice.pdf