IMPACT OF GERMINATION ON OLIGOSACCHARIDE CONTENT IN SELECT ASIAN INDIAN MINOR MILLETS

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1 Agric. Sci. Digest., 31 (1) : 14-19, 2011 AGRICULTURAL RESEARCH COMMUNICATION CENTRE / indianjournals.com IMPACT OF GERMINATION ON OLIGOSACCHARIDE CONTENT IN SELECT ASIAN INDIAN MINOR MILLETS Usha Ravi, Lakshmi Menon, K. Padmini and V. Sangeetha Department of Food Science, M.O.P Vaishnav College for Women, Chennai , India. Received : Accepted : ABSTRACT To study the level of oligosaccharides present in selected Asian Indian minor millets such as Varagu (Paspalum scrobiculatum), Samai (Panicum millare) and Thinai (Setaria italica) and the effect of germination on their oligosaccharide content. The select Asian Indian minor millets were obtained from local market and subjected to germination. The germinated and ungerminated samples were analysed for raffinose, stachyose and maltotetraose by extraction with hot water followed by High Pressure Liquid Chromatography analysis. The high oligosaccharide content (5 to 10%) was found in Thinai (Setaria italica). Raffinose content was around % in almost all minor millets. The oligosaccharide content in germinated minor millets reduced significantly due to enzymatic breakdown into simple sugars. Key words : Oligosaccharides, Minor millets, Germination, HPLC. INTRODUCTION Millet is a major crop in many of the countries, particularly Africa and Indian subcontinent where it covers almost 100 million acres and thrives in the hot dry climate that are not conducive to growing other grains such as wheat or rice. The millets are a group of small-seeded species of cereal crops or grains, widely grown around the world for food and fodder. They have been in cultivation in East Asia for the last 10,000 years. Minor millets are underutilized plant species that possess a small commercial value of production and trade compared to major agricultural commodities (Seetharaman and Rao, 2004). Traditionally minor millets are consumed as porridge in Asian India. These grains form an important constituent of weaning foods in rural India. Millets have an outer coat which is thicker than that of wheat, rice and corn, it is also known - usharavi62@gmail.com as coarse grain. On an average, 10 to 12 per cent of millet is protein. They are rich in insoluble fiber and micronutrients such as zinc, iron, calcium and oligosaccharides. Oligosaccharides are defined as polymers containing two to six monosaccharides linked through glycosidic linkage (Dykes and Rooney, 2007). Oligosaccharides occur naturally in plants, animals and microorganisms (Kuo et al., 1988). Non-digestible oligosaccharides possess functional properties like solubility, gelation, viscosity and cation binding, which attributes to the final quality of food (Niness, 1999). Despite numerous nutritional and functional benefits associated with foods containing high oligosaccharide content, it has been observed that weaning food preparation made with these foods can cause flatulence in infants (Hiryama, 2002). Oligosaccharides like raffinose and stachyose have

2 a beta-fructosidic linkage and an alpha-galactosidic linkage that leads to flatulence and thus considered undesirable. Kuo et al (1988) has stated that germination reduces certain oligosaccharide content, which helps in the reduction of flatulence. Thus this investigation was carried out to elicit the impact of germination on the oligosaccharide content of select Asian Indian minor millets. The minor millets chosen for the study were Varagu (Paspalum sorobiculatum), Samai (Panicum millare) and Thinai (Setaria italica). MATERIALS AND METHODS Preparation of ungerminated sample Varagu (Paspalum scrobiculatum) was procured from the local market. The grains were cleaned and soaked in distilled water (seed: water of 1:5 w/v) for 24 hours at 30 o C. Excess water was drained and the soaked grains were dried at 60 o C for 8 hours. The dried seeds were pulverized and sieved using a standard sieve of 60 mesh. Five grams of the powder was mixed with distilled water (1:40 w/v) and the mixture was heated in a water bath at 98 o C for 2 hours. The sample was cooled to 45 o C and the contents filtered using a muslin cloth followed by a filter paper. Similar process was adopted for preparing ungerminated Samai (Panicum millare) and Thinai (Setaria italica) sample. Preparation of germinated sample Varagu (Paspalum scrobiculatum) was procured from the local market. The grains were cleaned and soaked in distilled water (seed: water of 1:5 w/v) for 24 hours at 30 o C. The soaked grains were germinated separately in a sterile muslin cloth for 24 hours at 37 o C with frequent spraying of water. The sprouts were rinsed in distilled water and dried in a hot air oven at 60 o C for 8 hours. The dried seeds were pulverized and sieved using a standard sieve of 60 mesh. Five grams of the powder was mixed with distilled water (1:40 w/v) and the mixture was heated in a water bath at 98 o C for 2 hours. The sample was cooled to 45 o C and the contents filtered using a muslin cloth followed by a filter paper. Vol. 31, No. 1, Similar process was adopted for germinated Samai (Panicum millare) and Thinai (Setaria italica). Chemical analysis Moisture The millet flour (5 grams) was weighed and heated at 90ºC for 4 hours in hot air oven and the loss in weight was determined and calculated as the moisture content of the sample. HPLC (High Pressure Liquid Chromatography) method The determination of oligosaccharide content was performed by High Pressure Liquid Chromatography (HPLC) (Waters model Nr 2695 and refractive index detector of Nr 2414) with 70% acetonitrile as eluent. HPLC analysis was carried out using Waters spherisorb (5 µm), ammonia column (4.6mm and 250mm) at a temperature of 65 o C and flow rate of 1.6ml/ minute. Taking the peak areas in relation to the corresponding standards the oligosaccharides were quantified in dry matter basis. RESULTS AND DISCUSSION Moisture The results of the moisture content of the minor millets chosen for the study are presented in Table 1. The moisture content of all ungerminated samples varied between 1.2% to 3.6%. Ungerminated Varagu had the lowest moisture content of 1.2%. The moisture content of germinated millets ranged from 5.2%(Varagu) 11.4% (Thenai). Samai had the highest moisture content of 15.0 %. Thus it is evident that there is an increase in moisture content of minor millets after germination. Table 1 : Moisture content in raw and germinated millets. Sample Moisture % Raw Germinated Varagu ( Paspalum scrobiculatum) Samai (Panicum millare) Thinai(Setaria italica)

3 16 AGRICULTURAL SCIENCE DIGEST Table 2 : Oligosaccharide content in raw and germinated millets (dry weight basis mg/g). Sample Stachyose Raffinose Maltotetraose Raw Germinated Raw Germinated Raw Germinated Varagu Samai Thinai Germination is the process in which a seed or spore emerges from a period of dormancy. During germination, seeds absorb water by a process called imbibition (Jood et al., 1985). Swelling of seeds were observed on incorporation of water and it initiates germination through hydrolytic enzymes. Effect of germination on Oligosaccharide The results showed that oligosaccharide content of the germinated samples was less in comparison to the ungerminated samples. During germination, metabolic changes take place where in larger oligosaccharide molecules are broken down to smaller molecules (Robert et al., 1975). This shows loss of oligosaccharides during germination and the results obtained from HPLC analysis confirm that the oligosaccharides are significantly lost during germination. The results are tabulated in Table 2 and 3. Table 3 : Percentage loss of Oligosaccharide content in germinated millets. Sample Stachyose Raffinose Maltotetraose Varagu Samai Thinai Percentage loss of Oligosaccharide content in germinated millets: Samai (Panicum millare): It was noted that raffinose present in Samai(Panicum millare) decreased by 61.6% after germination. This can be attributed to the easy penetration of water. The results also showed a marked decrease in maltotetraose (86.5%) and stachyose (94%) due to the conversion of long chain oligosaccharides into simple sugars. This Fig 1 : Varagu raw.

4 Vol. 31, No. 1, Fig 2.: Varagu germinated. could also be attributed to the hydrolysis of oligosaccharides by á-galactosidase enzyme. Reddy and Salunkhe (1980). (Fig 3 and 4). Thinai (Setaria italica): It was noted that raffinose present in thinai (Setaria italica) decreased by 7.2% after 24 hours of germination. Stachyose decreased by 88.7%, probably due to the metabolic changes and hydrolysis that it undergoes during germination. Maltotetraose in thinai (Setaria italica) decreased by only 47.32% and thus showing that germinated thinai (Setaria italica) still contained higher amounts Fig 3.: Samai raw. of maltotetraose when compared to Samai or Varagu.(Fig 5 and 6). Varagu (Paspalum scrobiculatum): Raffinose present in Varagu (Paspalum scrobiculatum) decreased by 51.3% after 24 hours of germination. Stachyose decreased by 82.1% and Maltotetraose by 76.42%. (Fig 1 and 2). CONCLUSION This investigation revealed that germination is an easy processing method both at domestic and commercial level for reducing the oligosaccharide content of Asian Indian minor millets. This

5 18 AGRICULTURAL SCIENCE DIGEST Fig 4.: Samai germinated. Fig 5.: Thinai raw. Fig 6.: Thinai germinated.

6 Vol. 31, No. 1, investigation showed that the process of germination considerably decreased the Stachyose content in all the selected minor millets. Maltotetraose and Raffinose decreased by 50% in all samples. Hence it can be concluded that germination can be used as a processing methods for decreasing oligosaccharides in minor millets. However, combining germination with other processing methods can be explored for considerable reduction of oligosaccharide components in minor millets. REFERENCES Dykes, L. and Rooney, L.W. (2007) Phenolic Compounds in Cereal grains and their health benefits, Cer Fd. World, 52 : Hirayama, M. (2002) Novel physiological functions of oligosaccharides. Pure Appl Chem, 74: Jood, S, Mehta, U., Singh, R. and Bhat, C.M. (1985) Effect of processing on flatus producing factors in legumes. J Agri Food Chem, 33 (2) : Kuo, T.M, Middlesworth, J.F.V., Wolf, W.J. (1988) Content of raffinose oligosaccharides and sucrosein carious plant seeds. J Agri Food Chem 36 : Kyler, A.M. and Mc.Cready, R.M. (2005) Nutrient in seeds and sprouts of alfalfa, lentils, mung beans and soy beans. J Food Sci 40 : Niness, K.R, (1999) Inulin and oligofructose: J. Nutr, 129: Reddy, N.R. and Salunkhe, D.K. (1980) Changes in oligosaccharides during germination and cooking of millets and fermentation of rice blend. Cereal Chem 57: Robert, E.M., Miller, R.L. and Cushwa, C.L. (1975), Germination response to legume seeds subjected to moist and dry heat, Ecology; 56: Seetharaman, N and Rao, B.D. (2004) Cereals: Sustaining nutritional security. In: Survey of Indian Agriculture. The Hindu, pp:37-38.