Grain Quality Evaluation and Organoleptic Analysis of Aromatic Rice Varieties of Goa , India

Rice grain quality characteristics such as physical (hulling, length and breadth (L/B), grain classification, chalkiness, chalk index), chemical (alkali spreading value (ASV), amylose content (AC), gel consistency (GC), aroma), cooking (volume expansion, elongation ratio (ER), water uptake) and organoleptic-tests based on consumer preferences like appearance, cohesiveness, tenderness on touching, chewing, taste, aroma, elongation and overall acceptability were studied for fourteen aromatic rice varieties. The higher hulling percentage was recorded in ‘Ek-Kadi’ (82.46%) and ‘Ghansal’ (80.96%). The Length/Breadth (L/B) ratio among the varieties ranged from 2.08-4.85. No chalkiness was recorded in ‘Ghansal’, ‘Kotimirsal’ and ‘Pusa sugandh-2’. Among the varieties examined AC was ranged from 17.26-27.69%. The highest GC was recorded in ‘Ghansal’ and lowest in ‘Pusa Basmati-1’. Kernel length after cooking (KLAC) ranged from 2.31-5.88 mm. Water uptake ratio was ranged from 250-350. Organoleptic-test revealed that the varieties ‘Basmati local’, ‘Jiresal’, ‘Kotimirsal’, ‘Pusa Basmati-1’, ‘Pusa Sugandh-2’, ‘Pusa Sugandh-3’, ‘Pusa Sugandh-5', ‘Kasturi’ and ‘Vasumati’ were with excellent grain quality characteristics, preference and overall acceptability.


Introduction
India is one of the largest exporters of basmati rice in the world (Husaini et al., 2009).The consumers demand has increased markedly to pay a premium price for fragrant rice (Louis et al., 2005).Aroma in scented rice depends on the levels of 2-acetyl-1-pyrroline content and it varies with genetic and environmental conditions (Nadaf et al., 2006).Rice is the predominant food crop of Goa occupying an area of 39% (52 442 ha) of the total cultivated land in the state (Manjunath et al., 2009).The kernel appearance, size, shape, aroma, nutritional value and cooking characteristics are important for judging the quality and preference of rice from one group of consumer to another (Dela Cruz and Khush, 2000;Sellappan et al., 2009).
Kernel shape and L/B ratio are important features for grain quality assessment (Rita and Sarawgi, 2008).Aroma, hardness and roughness are depends on temperature and variety specific which affects the sensory properties of cooked rice (Yau and Huang, 1996).Individual preferences varied, most of the consumer's preferred imported rice but differed in their preferences for the local rice (Tomlins et al., 2005).

Study Objectives/purpose
In this paper, we are presenting the finding of grain quality characteristics (physical, chemical, cooking) and organoleptic analysis of traditionally cultivated scented rice varieties of Goa in comparison with basmati rice.

Plant material
The field survey was carried out in different parts of Goa and adjoining regions for the collection of scented rice varieties.

Physical traits
2.2.1 Hulling percentage 100 g of rice seeds were de-hulled using a standard de-husker and the average whole-grain yield was calculated (Anonymous 2004).

Grain Classification
Ten de-husked entire brown rice grains were measured using dial micrometer and based on the L/B ratio, grains were classified into long slender (LS), short slender (SS), medium slender (MS), long bold (LB) and short bold (SB) (Anonymous 2004).

Chalkiness of endosperm
Milled rice was observed under a stereo-zoom microscope and based on the orientation of chalkiness, the rice grains were classified into white belly, white centre and white back (Anonymous 2004).

Chalk index determination
Ten de-husked rice grains were placed on light box and visually identified the grain with more than 50% of chalkiness, weighed and percentage of chalkiness was calculated (Anonymous 2004).

Alkali spreading value (ASV) and Clearing test
Six milled rice grains were taken in Petri plates and 10 ml of 1.7% of KOH was added and kept in incubator at 27-30 °C for 23 hours.Then the alkali spreading value was calculated as low, low-intermediate, intermediate or high (Perez and Juliano, 1978).

Amylose content (AC)
To 100 mg of rice flour 1 ml of 95% ethanol and 9 ml of 1.0 N NaOH was added.This was mixed well and heated in a boiling water-bath for 10 min.Samples were diluted to 100 ml with distilled water.From this suspension, 5 ml of sample was taken and 1 ml of acetic acid (57.75 ml in one liter water) was added to acidify the sample along with 1.5 ml of iodine solution (0.2% iodine + 2% potassium iodide) and the volume was made to 100 ml with distilled water.The samples were incubated at room temperature for 20 min.The absorbance was measured at 620 nm using spectrophotometer.As a control, NaOH solution was used.The AC of different varieties was calculated in comparison with standard graph (Perez and Juliano, 1978).

Gel consistency (GC)
100 mg of rice flour was taken in test tube (2×19.5 cm), 0.2 ml of ethanol containing 0.25% thymol blue and 2.0 ml of 0.2 N of KOH were added and kept in boiling water-bath for 8 min, cooled, mixed well and kept in ice bath for 20 min.Later the test tubes were laid horizontally for one hour and measurements were made using graph paper.The degree of disintegration of kernel was evaluated using a 7 point scale (Bhattacharya, 1979).

Aroma
To 5 g of rice 15 ml of water was added, soaked for 10 min and cooked for 15 min, transferred into a Petri dish and placed in refrigerator for 20 min.Then the cooked rice was smelled by a random panel: strongly scented (SS); mild scented (MS); non scented (NS) (Anonymous, 2004).

Volume expansion ratio (VER) and elongation ratio (ER)
15 ml of water was taken in 50 ml graduated centrifuge tubes and 5 g of rice sample was added.Initial volume increase was measured (Y) and soaked for 10 min.Then increase in volume before cooking was noted (Y-15).Rice samples were cooked for 20 min in a water bath.Cooked rice was placed on bloating paper.Ten cooked rice kernels were selected (intact at both ends) and length of the kernels measured using graph paper for computing the kernel length after cooking (KLAC).Then the cooked rice was placed in 50 ml water taken in 100 ml measuring cylinder and increase in volume of cooked rice in 50 ml of water was measured (X).Then the volume raise was recorded (X-50).VER and ER were calculated (Anonymous, 2004).

Water Uptake
2 g of samples were taken in graduated test tubes with 10 ml of water and soaked for 30 min.As a control 10 ml of water was taken in 2-3 test tubes.All the test tubes were kept in water-bath for 45 min at 77 to 80 °C.After cooling, the supernatant of the samples were poured into graduated measuring cylinder and water level was noted.Similarly control water was measured.Then water uptake was calculated as 100/2 g × actual water absorbed (Anonymous, 2004).

Organoleptic test
To 5 g of rice samples 15 ml of water were added and soaked for 10 min.Rice samples were cooked in water bath for 15 min and scored as per panel test performance (Anonymous, 2004).

Statistical analysis
All the experiments were carried out using three replicates.The data were analyzed by using a statistical software WASP-2.0.

Physical characteristics
The hulling percentage for traditionally cultivated scented and basmati rice varieties ranged from 72-82 (Table 1).The highest hulling (82.4%) was noted in variety 'Ek-Kadi' and lowest in 'Basmati local' and 'Kasturi' (72%), whereas intermediate value was recorded in 'Pusa Sugandh-2' (77.4%).High hulling percentage resulted in higher head rice yield of 93.3% in parboiled rice with the higher (5.5 x 104 N/m2) process steam pressure (Igbeka et al., 2008).Rita and Sarawgi (2008) reported that the more than 80 value of hulling percentage is preferred and if the hulling percentage increases the head rice recovery also increased.Irregular cracks are caused in rice by hot-air drying but wetting of paddy tended to get healed upon long soaking (Swamy et al., 2009).

Chemical characters
The alkali spreading value (ASV) and gelatinization temperature (GT) were calculated for all the rice varieties examined.The low ASV and high GT were detected in 'Basmati local' and 'Mugadh Sugandh'.The intermediate ASV and GT were noted in varieties such as 'Ghansal', 'Girga', 'Jiresal', 'Kotimirsal', 'Pusa Sugandh-2', 'Pusa Sugandh-3' and 'Kasturi'.The high ASV and low GT were recorded in high yielding varieties viz.'Pusa Basmati-1', 'Pusa Sugandh-5' and 'Vasumati', whereas low-intermediate ASV and high-intermediate GT was observed in traditional scented rice variety 'Ek-Kadi' (Table 3).Cooking time of the rice depends on coarseness of the grain.The intermediate ASV indicated the medium disintegration and classified as intermediate GT which highly desirable for quality grain (Bansal et al., 2006).
The rice varieties were examined for amylose content (AC) and classified as waxy, very low, low, intermediate and high AC.Among the varieties studied, AC ranged from 17.26-27.69%.The lowest level of AC was recorded in 'Kotimirsal', whereas highest in 'Mugadh Sugandh'.Most of the traditional aromatic varieties showed low AC content in comparison with basmati rice varieties (Table 3).Shahidullah et al., 2009 reported that the AC in all grades of rice ranged between 20.7-21.4%.Cooked rice becomes moist and sticky due to low AC.Amylose and amylopectin in kernels determine the texture of cooked rice and consumers prefer rice with intermediate AC.
The gel consistency (GC) was measured into soft, medium and hard.The GC of the rice samples ranged from 65-70 mm and categorized as soft, this means the tendency of cooked rice to be soft on cooling.The length of the blue gel was high in aromatic traditionally cultivated rice varieties 'Girga' 20.46 mm and lowest in 'Kotimirsal' 17.26 mm.In basmati rice 'Mugadh Sugandh' recorded high 27.69 mm and the lowest in 'Kasturi' 21.83 mm (Table 3).Amylose content, starch, gel consistency and non-reducing sugar content decrease with elevated temperature (Pandey et al., 2007).
Aroma is an important trait, has high demand in the global market.The native varieties studied during this investigation showed the presence of aroma, for which these varieties are preferred by local people for consumption.Mild aroma was detected in varieties like 'Basmati local', 'Ek-Kadi' and 'Mugadh Sugandh'.'Ghansal', 'Jiresal', 'Pusa Sugandh-5', 'Kasturi'and 'Vasumati' were more scented than other varieties.The strong aroma was detected in 'Pusa Basmati-1', 'Pusa Sugandh-2' and 'Pusa Sugandh-5' (Table 3).Nadaf et al., 2006 reported that Basmati rice contains more aroma than the traditionally cultivated scented rice varieties.

Cooking characteristics
The volume expansion ratio (VER) in aromatic traditional rice varieties ranged from 2.36-4.10,while in basmati varieties 2.73-3.63.'Pusa Sugandh-5' showed the VER 3.63 and 'Mugadh Sugandh' with 2.73 (Table 4).It was reported that lower VER is preferred by the consumers than higher VER, on the other hand, higher elongation ratio (ER) of the cooked rice is preferred than lower ER (Shahidullah et al., 2009).Kernel length after cooking (KLAC) ranged from 2.31-3.76mm in aromatic traditionally cultivated rice and 4.62-5.88mm in basmati rice.Minimum KLAC was observed in 'Kotimirsal' and 'Basmati local'.Kernel elongation ratio (ER) in aromatic traditional rice ranged from 1.01-1.42and basmati rice ranged from 1.02-1.12.Highest kernel ER was observed in 'Ghansal' and lowest in 'Masuri' (Table 4).
In basmati varieties, water uptake ratio ranged from 280-335 and in aromatic traditional rice varieties 250-350.Among the traditional rice varieties, 'Ek-Kadi' recorded the highest water uptake ratio and minimum in 'Masuri' (Fig. 1).The amount of water uptake during cooking process is associated with the appearance of cooked rice (Tan et al., 2000).

The Organoleptic Analysis
The organoleptic-test was conducted for the appearance, cohesiveness, tenderness on touching, tenderness on chewing, taste, aroma, elongation and overall acceptability of cooked rice and evaluated by trained assessors using the above descriptive analysis in a control panels.Sensory specifications are those that can be used to check if a product complies with the stated requirements Costell 2002.The excellent overall acceptability characters were recorded in 'Basmati local','Jiresal','Kotimirsal','Kasturi' and 'Vasumati'.The good overall acceptability was observed in varieties 'Ek-Kadi', 'Ghansal', 'Girga', 'Masuri' and 'Mugadh Sugandh' (Table 5).

Conclusions
The paper has concentrated on the physical, chemical, cooking characteristics and organoleptic test with consumer preferences of traditionally cultivated scented and basmati rice varieties.Among the varieties studied traditionally cultivated aromatic rice 'Ek-Kadi' and 'Ghansal' showed maximum hulling percentage.The AC, ASV and GC were excellent in 'Girga', 'Ek-Kadi', 'Mugadh Sugandh', 'Pusa Basmati-1' and 'Pusa Sugandh-3'.The study revealed that the rice varieties viz.'Basmati local', 'Jiresal', 'Kotimirsal', 'Pusa Basmati-1', 'Pusa Sugandh-2', 'Pusa Sugandh-3', 'Pusa Sugandh-5', 'Kasturi' and 'Vasumati' with best cooking quality characteristics and consumer's preference.Organoleptic analysis always helps the consumers to select better rice varieties for their consumption and use.It is also emphasized that the training and recruiting the sensory expert panel are important in the process of sensory analysis and organoleptic test (Lefebvre et al., 2010).The present study revealed that some of the indigenous aromatic rice varieties have potential for consumer's preferences and it could be used for breeding programmes and biotechnological research for the improvement of valuable grain quality traits.

Table 1 .
The hulling percentage, L/B ratio and grain classification of aromatic traditionally cultivated and basmati rice varieties

Table 2 .
The chalkiness frequency, kernel area of chalkiness, type and percentage of chalkiness in aromatic rice varieties Superscript letters (a-h) indicate significant differences (p < 0.05) among different rice varieties.Means with same letter within column are not significantly different (p < 0.05), means ± SD, VOP, very occasionally present; OC, occasionally present; P, present; ND, not detected.

Table 3 .
The alkali spreading value (ASV), gelatinization temperature (GT), amylose content (AC), gel consistency (GC) and aroma in aromatic traditionally cultivated and basmati rice varieties Superscript letters (a-f) indicate significant differences (p < 0.05) among different rice varieties.Means with same letter within the column are not significantly different (p < 0.05), means ± SD, L, Low; I, Intermediate; LI,

Table 4 .
The volume expansion ratio, kernel length after cooking, kernel elongation ratio and water uptake in aromatic traditionally cultivated and basmati rice varieties Superscript letters (a-g) indicate significant differences (p < 0.05) among different rice varieties.Means with same letter within column are not significantly different (p < 0.05), means ± SD.
d Hard O Figure 1.Water uptake in aromatic traditionally cultivated and basmati rice varieties