Effect of Pre-treatments and Methods of Drying on Quality of Kumutia (Acacia senegal (L) Willd.) Seeds Choudhary MR1, Dadheech S2, Jakhar ML3,*, Garhwal OP4 1Associate Professor, Department of Horticulture, Shri Karan Narendra College of Agriculture, Jobner, Jaipur, Rajasthan, India 2Subject Matter Specialist (Horticulture), Krishi Vigyan Kendra, Bhilwara, Udaipur. Rajasthan, India 3Associate Professor, Department of Plant Breeding and Genetics, Shri Karan Narendra College of Agriculture, Jobner, Jaipur, Rajasthan, India 4Subject Matter Specialist (Horticulture), Krishi Vigyan Kendra, Nagore, Rajasthan, India *Email id: mljakhar@yahoo.com
Abstract The present investigation was carried out to determine the impact of different processing and drying treatments on the quality of kumutia seeds. Seeds were collected from matured pods and subjected to processing namely blanching in four different salt concentrations (1%, 2%, 3% and 4%) followed by three drying methods (shade, solar and oven). The dried seeds were then stored for six months and observations on various quality parameters were taken at 0, 3rd and 6th month of storage. The kumutia seeds blanched in 3% salt solution and dried in a solar drier gave a better quality dried product under storage for a duration of 6 months. Such treated products have good nutritive value and can be used to prepare off-season vegetable dishes. Top Keywords Isotherm, Solar drying, Proteins, Blanching. Top |
Introduction A. senegal (Fam.: Mimosoideae) the popular species of arid zone, is well known for its medicinal qualities, nutritional qualities and various industrial uses. It is a small thorny deciduous tree, which attains a height of 3–5 m (rarely 9 m) with 30–60 cm stem girth (Dhaka et al., 2008). The tree bears pods that are 5–8 cm by 1.8–2.5 cm thin, flat and straight, contains 5–6 seeds in each pod. The pod ripens in the end of September to November, are thin, brittle and brown coloured when mature. Aproximate composition (Dry matter basis) of kumutia seeds is 38.89% crude protein, 10% ether extract, 20.56% crude fibre, 5% ash, 25.55% nitrogen free extract (total digestible carbohydrate), 0.320% calcium, 0.170% magnesium, 0.018% sodium, 1.253% potassium, 0.484% phosphorus, 42.50 ppm zinc, 30 ppm copper, 475 ppm iron and 75 ppm manganese (Balogun and Fetuga, 1986). |
Pachkuta is an important vegetable dish of star hotels, in which five dried fruits and vegetables are mixed together and cooked. Kumutia is one of the important components of it. Production of good quality dried products is essential to achieve the best quality pachkuta and other vegetable dishes. Dried and preserved seeds of kumutia are palatable and commonly used in dessert as well as in a vegetable dish in star hotels, because it is tasty, nutritionally rich and the only source of protein content for tribal population where other sources are negligible. The seed of this specie has an acrid taste, which requires processing treatment to remove its acridity. Blanching in different concentration of salt and drying with appropriate method checks the enzymatic spoilage and also improves the colour, texture and taste. Thus, the present investigation was undertaken to evaluate the effect of pre-treatments and methods of drying, on the quality and storage stability of the seeds of kumutia. |
Top Materials and Methods The present investigation was conducted at the Department of Horticulture, S.K.N. College of Agriculture, Jobner. Kumutia pods were procured from Choudhary Farm, village Bhadwa, District Jaipur (Rajasthan). There were 12 treatment combinations including four salt (NaCl) concentrations namely, 1% (S1), 2% (S2), 3% (S3) and 4% (S4) and three methods of drying namely, shade drying (D1), solar drier drying (D2) and oven (D3). The experiment was laid out in a completely randomised design (CRD) with three replications. Fully matured pods were selected and seeds were separated out from it. The sample of a 1-kg seed was used for each treatment of different salt concentration applied by blanching them in their respective concentrations of brine solution in boiling water for 6 minutes. The duration of blanching for 6 minutes was standardised through catalase and peroxidase tests in the laboratory. After processing, these seeds were dried under respective methods of drying namely, shade, solar drier and oven. After drying under the respective method, the dried kumutia seeds were packed into 250 gauge polyethylene pouches. The packed samples were stored in a dry place at 20–25oC and 30–36% relative humidity for six months and were analysed at 0, 3rd and 6th month of storage for various quality parameters. |
Observations on equilibrium relative humidity were recorded at once, that is, just after drying (at 0 month) while for the remaining parameters it was at the 0, 3rd and 6th month. Rehydration ratio is ratio of the drained rehydrated product to weight of the dried product. Ascorbic acid (vitamin C) was measured as suggested by Ranganna (1995). Crude protein was estimated by determining the total nitrogen content through colorimetric method (Snell and Snell, 1939) and then multiplied it with factor 6.25. |
Non-enzymatic browning (NEB) of dried kumutia seeds was measured by recording the optical density (O.D.) of the extract at 420 nm (Ranganna, 1995). Equilibrium relative humidity (ERH) was determined by Wink's weight equilibrium method (1946). Organoleptic acceptance was recorded by a panel of five judges who scored marks for different treatments at the 0, 3rd and 6th month of storage by Headonic Rating Test (1965). These scores were used to evaluate the quality of the dried product (kumutia seeds) as well as the dish (curry) prepared from it for colour, texture, taste and flavour. Scores were expressed on a 0–9 scale and averaged. To test the significance of variation in the data, analysis of variance in technique was adopted as suggested by Gomez and Gomez (1984). |
Top Results and Discussion Rehydration Ratio The highest rehydration ratio was recorded with salt at 2% and solar drier drying followed by salt at 1% and solar drier and salt at 3% and solar drier drying however, these treatments were found statistically at par with each other (Figure 1). Rehydration ratio is a measure of the injuries to the material caused by drying and treatments preceding dehydration. Thus, the higher rehydration ratio, less damage is done to the tissues caused by the drying process and greater the product hydration (Davoodi et al., 2007). The study also revealed that there was a gradual decline in rehydration capacity of the dried product during storage period of 0–6 months, possibly due to impaired texture with the advancement of time. This may also be attributed to reduction in water binding sites due to chemical and structural changes in the major components of dehydrated products brought about during storage. The decrease in rehydration ratio during storage was also observed by Mehta and Tomar (1982) in dehydrated mango slices. Ascorbic Acid The retention of ascorbic acid (Figure 2) was highest in seeds treated with 4% salt concentration and dried in shade (S4D1) followed by 3% salt and shade dried (S3D1), 2% salt and shade dried (S2D1), 4% salt and solar drier (S4D2), 3% salt and solar drier (S3D2). This might be attributed due to inactivation of oxidases, which is responsible for the degradation of ascorbic acid content and inhibition of oxidative changes of ascorbic acid. Almost similar results have also been observed by Ramarao et al. (1956) in aonla powder. Ascorbic acid content of dehydrated kumutia seeds decreased further when stored for six months. The reduction in ascorbic acid content might be due to oxidation during storage at a high ambient temperature. This finding is in confirmation with Mufat Lal (2001) and Fageria et al. (2003). Protein Content The protein content of kumutia seeds were significantly influenced with methods of drying. Among methods of drying, solar drier (S2) exhibited significantly higher protein content during the storage period, although present study revealed a continuous decrease in protein content during storage irrespective of the treatments (Figure 3). This gradual decline in protein content during storage was possibly due to increased protinase activity. Rama and John (2000) and Fageria et al. (2003) also reported that both blanching and storage reduced the protein content in dehydrated products. Non-enzymatic Browning Optical density of the products was determined as an index of browning. Regarding Figure 4, the change in non-enzymatic browning (NEB) due to blanching in different salt concentrations and drying methodsshowed that the minimum optical density was recorded as 4% in salt and solar drier (S4D2) followed by 3% in salt and solar drier (S3D2) and 4% in salt and shade drying (S4D1). This might be due to the high concentration of salt checked by the microbial degradation and scorching heat of the product during the drying process that helped in lowering down the non-enzymatic browning. The results are in confirmation with Choudhary et al. (2007) in kachri. NEB (OD) of dried/dehydrated seeds just after drying was lowest but increased significantly during storage. The increase in browning might be due to the wide range of residual peroxidases and lipooxigenases even after blanching. Oxidation of ascorbic acid provide the carbonyl compounds that subsequently reacted with amino groups and polymerised to give brown pigments (Bhardwaj and Lal, 1989). Organoleptic Score The values for organoleptic acceptance (Table 1) was found to be highest in treatment of salt 4% and solar drier (7.03), followed closely by treatment of salt 3% and solar drier (7.02) at the 6th month of storage. The highest values for organoleptic acceptance indicated an acceptable quality of the dried product with regard to its colour, flavour, taste, texture and retaining the quality. Blanching of seeds in higher concentrations of salt (3% or 4%) and drying under the solar drier method helped in separating/discarding the anti nutritional compounds of dried products. These results are in close conformity with those of Mehta and Tomar (1982) and Choudhary et al. (2007). The values for organoleptic acceptance were decreased gradually with the advancement in storage period. A similar trend in the reduction of values for organoleptic acceptance during storage was also observed by Lal (2001) and Fageria et al. (2003) in kachri, lehsua and ker fruits. Sorption Studies The sorption study on dehydrated kumutia seeds is presented in Table 2. Equilibrium relative humidity of dehydrated seeds was 50% with an initial moisture content of 4.35% (Table 2 and Figure 5). At higher relative humidity, the product had a tendency to gain moisture and above 50% relative humidity it turned soft in texture with slight change in colour and flavour. As the dried kumutia seeds equilibrated at 50% relative humidity they could be turned as hygroscopic. Mould growth in the dried kumutia seeds was noticed at 80%, 90% and 100% relative humidity after 31, 29 and 24 days of storage, respectively. The critical point and danger point were at moisture level of 11.51% and 9.00%, respectively. The portion of the curve between danger (D) and critical (C) points is generally defined as safety range and that between optimum (M) and danger (D) points is known as safety margin (SM). It is a helpful guide to choose a packaging material for safe storage of dehydrated products. Similar work has also been carried out by Sagar and Khurdiya (1997) and Sagar and Roy (1997) where, they recorded 50% RH as optimum RH of the dehydrated product. Top Conclusion It is concluded that kumutia seeds blanched in 3% salt solution and dried in solar drier gave a better quality dried product under storage for a duration of six months. There was a better retention of nutrients like ascorbic acid, protein content and lower non-enzymatic browning. The colour of the dried products was very good compared with the other methods. The optimum relative humidity was 50% for the storage of dried kumutia seeds having 4.35% initial moisture. This type of prepared products can be used to prepare off-season vegetable dishes with good nutritive values. |
Top Figures | Figure 1:: Effect of drying methods and salt concentration on rehydration ratio of kumutia seeds
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| | Figure 2:: Effect of drying methods and salt concentration on ascorbic acid content of kumutia seeds
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| | Figure 3:: Effect of drying methods on protein content of kumutia
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| | Figure 4:: Effect of drying methods and salt concentration on Non-enzymatic browning of kumutia seeds
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| | Figure 5:: Equilibrium relative humidity curve for dehydrated kumutia seeds at room temperature
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Tables | Table 1:: Effect of salt concentrations and methods of drying on the organoleptic score of kumutia seeds
| | S.No. | Treatments | Organoleptic score | | 0 month | 3 month | 6 month | | 1. | S1D1 | 7.31 | 6.88 | 6.04 | | 2. | S1D2 | 7.74 | 7.30 | 6.48 | | 3. | S1D3 | 7.51 | 7.09 | 6.35 | | 4. | S2D1 | 7.36 | 6.91 | 6.27 | | 5. | S2D2 | 8.05 | 7.55 | 6.85 | | 6. | S2D3 | 7.60 | 7.14 | 6.47 | | 7. | S3D1 | 7.51 | 6.99 | 6.43 | | 8. | S3D2 | 8.21 | 7.70 | 7.02 | | 9. | S3D3 | 7.57 | 7.15 | 6.47 | | 10. | S4D1 | 7.54 | 7.07 | 6.48 | | 11. | S4D2 | 8.17 | 7.67 | 7.03 | | 12. | S4D3 | 7.66 | 7.19 | 6.59 | | SEm + | 0.05 | 0.05 | 0.05 | | | CD (P=0.05) | 0.14 | 0.15 | 0.15 | |
| | | Table 2:: Effect of salt concentration and methods of drying on equilibrium relative humidity (ERH) of dehydrated kumutia seeds at room temperature
| | Equilibrium moisture content (%) | ERH (%) | No. of days required to reach equilibrium | Remarks | | 1.20 | 11.1 | 86 | Colour light brown, texture hard, flavour original | | 1.82 | 20.4 | 82 | Colour light brown, texture hard, flavour original | | 2.75 | 31.9 | 72 | Colour slightly light brown, texture slightly hard, flavour original | | 4.94 | 40.2 | 58 | Colour slightly light brown, texture slightly hard, flavour original | | 8.62 | 49.0 | 53 | Colour slightly light brown, texture slightly hard, flavour normal | | 14.75 | 61.8 | 46 | Texture soft, colour and flavour slightly changed | | 18.22 | 67.7 | 39 | Product soft, colour dark brown | | 25.02 | 79.1 | 31 | Product very soft, mould growth seen after 31 days | | 34.39 | 91.1 | 29 | Product watery, mould growth seen | | 41.15 | 100 | 24 | Mould growth seen |
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