IJCRR

IJCRR - 11(12), June, 2019

Pages: 16-24

Date of Publication: 19-Jun-2019

Post Harvest Evaluation of Rice Hybrids for Grain and Cooking Qualities

Author: Anirban Nath, Disharee Nath, Chand Kumar Santra, Tapash Dasgupta

Category: Life Sciences

Abstract:Background: For commercial exploitation of rice hybrids, superior grain and cooking qualities are prerequisites. The current study evaluates thirty eight rice hybrids in terms of important grain and cooking quality parameters.
Materials and Methods: Performances associated with grain quality parameters like Hulling%, Milling%, Head rice recovery%, Kernel length, Kernel Breadth and L/B ratio were recorded. In case of cooking qualities, characters like Amylose content, Gel consistency, Alkali spreading value, Gelatinization temperature, Elongation ratio and water uptake were estimated. The data obtained from the quality performances were also compared with consumer preferences reported by earlier authors.
Results and Discussions: As per earlier reports, rice millers prefer 80 % Hulling, 70% milling and 65% head rice recovery. From the consumer's perspective long slender kernel, intermediate amylose, soft gel and intermediate gelatinization temperature are prerequisites. In the current investigation the hybrids like ADTRH1, GK5003 and Suruchi exhibited superior performances for all the grain qualities but lacked in one or more cooking quality parameters. On the contrary, hybrids like IR58025A x IR10198R, IR79156A x IR40750R, Sahyadri4, PSD 3 and PusaRH-10 exhibited superior cooking quality traits but lacked in one or more grain quality parameters. The hybrid IR80559A x IR6876-1 was the best performer fulfilling the criteria for most of the grain and cooking quality traits. A Correlation coefficient analysis was performed and significant correlations among the quality traits were elucidated. The analysis revealed that hulling (%) and head rice recovery (%) were significantly correlated with milling (%). Similarly Amylose content was negatively correlated with gel consistency.
Conclusions: The hybrids showing superior grain and cooking qualities can be recommended for commercial production. The vital correlations can be used as tools for selection in terms of grain and cooking qualities.

Keywords: Hybrid rice, Hulling, Milling, Head rice recovery, Amylose content, Gel consistency, Gelatinization temperature, Correlation coefficient analysis

Full Text:

Introduction:

The high grain yield attributed by hybrid vigour will only be worthwhile if ultimately the rice obtained is of high quality in terms of grain and cooking properties. In the absence of adequate grain and cooking quality associated with the grain obtained, the hybrid rice finally produced from a breeding program will be commercially inefficacious. Compared to other cereals, grain quality of rice is of crucial importance and determines the market price since rice is consumed as a whole grain. Also, the preferences in terms of cooking quality vary from region to region. In general, few desirable quality parameters like high milling %, head rice recovery %, grain shape, appearance, cooking qualities, palatability, etc are emphasized across rice growing regions. In most countries including India ‘long grain’ type of rice which is soft and non-sticky upon cooking are preferred over ‘short grained’ Japonica types which are sticky on cooking resulting from a low amylose content. In case of hybrid rice, achieving superior grain and cooking quality is challenging. Firstly the consumed grains belong to F₂ generation. Secondly the sterile cytoplasm has significant influence on the quality traits associated with the grain as reported by Shivani et al. (2007), Yi and Cheng (1992), Virmani et al. (2003). The current study aims at evaluating 13 new hybrids (unreleased) and 25 commercially released hybrids for their physical grain and cooking qualities.

Materials and Methods

The experiment was performed using 38 rice hybrids comprising of 13 newly identified and 25 released hybrids from public and private sectors. The list of germ plasm evaluated in the current experiment is mentioned in the Table 1. For the analysis of quality traits, post-harvest seeds kept at a moisture level of 12 to 15% were used. After 60 days of harvest, the grain and cooking qualities were estimated.

Characterization of Grain physical parameters:

The vital grain quality characters like Hulling and Milling %, Length of Kernel, Breadth of Kernel, Length-breadth ratio and Head Rice Recovery% were evaluated. For estimating hulling % (HL) Paddy de husker (Satake, Japan Model – THU-35B) was used. For estimating Milling % (ML), replicated paddy seeds were milled using the rice miller (Satake, Japan Model – TMO 5C & TM – 05). Head rice recovery % (HRR) was estimated using 4 months old seeds as suggested by Khush et al. (1978). Head rice was separated using the (Satake Japan, Model no.TRGO58). The hulling %, milling % and Head rice recovery% were calculated as per Singh (2000). The Kernel Length (KL) and Kernel Breadth (KB) were measured using Dial Thickness Gauge (Mitutoyo, Japan, Range: 0.01- 20 mm). The LB ratio was calculated by dividing KL by KB. The Kernel Length was classified as ≥7.50mm (very long), 6.61 to 7.50(Long), 5.51 to 6.60 (Medium or intermediate) and ≤5.50 (short). The LB ratio was classified as ≥3.0 (slender), 2.1 to 3.0 (medium), ≤ 2.0 (bold).

Characterization of hybrids with respect to cooking quality parameters:

Cooking quality and palatability of rice are influenced predominantly by the properties of starch, which corresponds to 90% of the milled rice recovered. The physical and chemical properties of starch can be approximated by the amylose content, gel consistency and alkali spreading value observed in the milled rice. In the current study Amylose Content (AC) was estimated following Sadasivam and Manikam (1992). Classification of grain type based on amylose content into waxy (0-2%), very low (3-9%), Low (10-19%), intermediate (20-25%) and High (>25%) was done following Kumar and Khush (1986). For determining the texture of the cooked rice, gel consistency (GC) was estimated and classified following Cagampang et al.(1973). For determining the cooking temperature of the milled rice the gelatinization temperature (GT) was estimated using the Alkali spreading value (ASV). ASV was determined following Little (1958). The ASV and GT was scored following Singh (2000). The cooked rice properties like Elongation ratio (ER) and Water uptake (WU) were also estimated. The ER was estimated by dividing length of cooked rice by uncooked Azeez and Shafi (1966).

Results and discussion: 

The performances of the hybrids in terms of grain physical qualities are discussed in Table 2. In terms of hulling and milling percentages the best performing hybrid was Indira Sona with 84.22% and 75.24 % hulling and milling recovery respectively. The highest head rice recovery% was observed in GK5003 (69.24 %). For the new crosses, the highest HL and ML was observed in IR69897A x CNR102 with 82.47 % and 75.21% hulling and milling recovery respectively. The highesr HRR (%) among the new crosses was observed in IR80559A X IR6876-1 (65.27 %). In terms of grain physical appearance, a long grained rice (long slender/medium) are highly marketable Kaul (1970), Singh et al. (2000). The grain type revealed that 26 out of 38 hybrids were long grained of which 24 are long slender and 2 hybrids were long medium.

The cooking quality parameters of the hybrids were evaluated and discussed in Table3. The elongation ratio of the cooked rice was calculated. The highest elongation ratio (ER) was observed in PA 6444 (1.9). In case of amylose content, an intermediate value (20 to 25 %) is preferred by the consumers in the Indian sub continent. In the current study 28 out of 38 hybrids exhibited an intermediate level of amylose. For determining the texture of the cooked rice, gel consistency was estimated. The Gel consistency suggests that 6 out of 38 hybrids exhibited a soft gel with a gel migration of ≥ 61mm. These hybrids can be presumed to maintain a soft texture in the cooked rice which is highly desired by consumers Tang et al. (1991). For determining the temperature required for cooking, Alkali spreading value indicating the GT was estimated. In case of Gelatinization temperature, 29 out of 38 hybrids exhibited an intermediate range of 70 to 74 ºC. An intermediate cooking temperature is desired by the consumers Bansal et al. (2006).

From the commercial perspective earlier reports indicated specific criteria which are to be fulfilled in terms of quality parameters. Fulfillment of these criteria can ensure marketability for the hybrids. Bisne and Sarawgi (2008) indicated 80% hulling percentage is required for marketability of a rice cultivar. Similarly 70% milling recovery and 65% head rice recovery was suggested by Cruz and Khush (2000), Bhonsle and Sellappan (2010) respectively. For cooking qualities, intermediate amylose (20-25%), Soft gel consistency and intermediate gelatinization temperature were recommended Cruz and Khush (2000) Tang et al. (1991), Bansal et al.(2006)  respectively. Based on the fulfillment of such standards, performances of the hybrids in terms of quality traits were scored in the form of presence (+) or absence (-) in Table 4. It reveals that, none of the hybrids could fulfill all the criteria suggested. The hybrids IR58025A x IR10198R, IR79156A x IR40750R, Sahyadri 4, PSD 3 and Pusa RH-10 exhibited superior cooking qualities in addition to long (slender/medium) grain types but lacked in traits like hulling, milling and head rice recovery. Whereas ADTRH1, GK5003 and Suruchi fulfilled the superior grain quality parameters like hulling, milling and head rice recovery but lacked in one or more cooking qualities. The hybrid IR80559A x IR6876-1 fulfilled almost all the criteria for high performance with respect to both grain and cooking qualities only drawback being slightly low hulling percentage.

Since the grain and cooking quality parameters are highly complex, prediction of performance becomes highly challenging and tedious. In such cases understanding the mutual association between the quality traits is very helpful. Thus based on the performances of the hybrids, a correlation coefficient analysis was performed (Table 5).

The correlation coefficient analysis indicated that the hulling % and head rice recovery % are positively correlated with milling %. Such correlations were also observed by Manonmani and Khan (2003). Hulling % and Head rice recovery % were also observed to be positively correlated. Influence of hulling percentage upon head rice recovery % was mentioned by Bisne and Sarawgi, (2008) who suggested that 80 % hulling percentage can enhance head rice recovery expected in the hybrids. From such observation it can be suggested that superior performance for any one of these three traits can indicate a desirable performance for the others. A significantly positive correlation was observed between Kernel length and L/B ratio. Similarly a significantly negative correlation at 1% probability was observed in case of kernel length and kernel breadth as well as between kernel breadth and L/B ratio. Thus from such observations it can be suggested that larger kernel length can indirectly ensure reduction of grain breadth and increase of L/B ratio. Such hybrids can be expected to produce long slender or long medium grain type. Significant correlations among the characters associated with grain shape has been also reported by Hussain et al.(1987), Naik  et al.(2005), Rajamani et al. (2004).

Since cooking quality of rice is highly influenced by the grain amylose content, the correlations involving amylose content is worth analyzing. The amylose content of the grains were found to be positively correlated at significantly high probabilities with alkali spreading value. Such observations suggest that selection for the intermediate levels of amylose can indirectly ensure the intermediate GT. Such Intermediate   GT within a range of 70 to 74ºC is a desired attribute in terms of cooking quality. The positive association between the two traits was also suggested by Jennings et al.(1979).

Another strong correlation associated with amylose was observed in case of Gel consistency. The two traits were negatively correlated at high probabilities. Thus increase of amylose will lead to hard gel consistency with short gel flow and for low amylose the gel will be soft with a longer gel flow. This occurs as a result of the retrogradation behavior of amylose during cooling as suggested by Rani et al. (2006). Gel consistency determines the texture of the cooked rice after cooling down of rice following the completion of the cooking process. Thus selection of hybrids for desirable amylose content can ensure desirable texture for the cooked rice. The negative correlations between gel consistency and amylose content was reported earlier by Khatun et al. (2003). Apart from the above mentioned correlations which can be exploited for determining the desired grain and cooking quality parameters, many other correlations have been observed between the grain and quality traits. These correlations indicate the nature of interactions among the traits and the complex network of genetic interactions which influence these quality characters.

Conclusions:

The performances of the hybrids in terms of important quality traits provided vital inputs on the expected marketability of the hybrids. The study suggested that the cross combination IR80559A x IR6876-1 was the best performer showing desirable results for both grain and cooking qualities. Thus the hybrid can be expected to be commercially desirable. Other crosses like IR58025A x IR10198R, IR79156A x IR40750R, Sahyadri 4, PSD 3 and Pusa RH-10 exhibited superior cooking qualities but lacked in grain qualities. The loss of head rice recovered in these lines can be avoided if they are consumed as brown rice. Similarly hybrids like ADTRH1, GK5003 and Suruchi performed well in terms of grain qualities but showed drawbacks in case of cooking qualities. These hybrids can be used for making rice based products. The results from the correlation coefficient analysis identified the traits which can influence multiple grain and cooking qualities. Evaluation of hybrids for these traits can in turn provide an approximate idea about the performances for other quality traits.

Acknowledgement:

Authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed. The authors extend their gratitude towards the project “Crop Breeding Research Unit” funded by Department of Agriculture, Govt. of West Bengal, India and Rice Research Station, Chinsurah, Hooghly Govt. of West Bengal for providing infrastructural support.

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