Development and Optimization of Traditional Product Rabdi Doodh and Its Quality Assessment

International Journal of Excellence Innovation and Development ||Volume 2, Issue 1, Jan. 2019||Page No. 021-024||

Development and Optimization of Traditional Product Rabdi Doodh and Its Quality Assessment Umair Saeed Randhawa, Mazhar Saeed Randhawa, Dua Abrar University of Agriculture Faisalabad, Pakistan

Abstract––Rabdi doodh is a popular concentrated and sweetened milk based drink which is quite popular in Pakistan and India. It is an intermediate product of rabdi processing and have very refreshing effect especially in hot season. Up till now no work has been reported on optimization and commercialization of rabdi doodh with standard quality and shelf life. This study was aimed to develop a balanced recipe of rabdi doodh with uniform quality along with relatively longer shelf life. The product was prepared by standardizing total solids with Khoya and sugar to three different levels 20% (R1), 25% (R2) and 30% (R3). Product was stored at 4°C for 28 days and physiochemical analysis was done at every 7th day’s interval. The results have shown significant reduction in fat (7.75% to 6.95%), in lactose (7.24% to 5.99%), in protein (6.45% to 5.86%) and in pH (6.79 to 5.68) in overall mean values during storage period. The mean values for titrable acidity were significantly increased from 0.06% to 0.47% at the end of study. The overall acceptability was significantly improved by increasing total solids and R3 scored maximum (7.75) while R1 scored minimum (6.41) points in sensory evaluation.

Keywords––Development, Optimization, Quality assessment, Rabdi doodh

INTRODUCTION Milk is a complete diet and commonly used food item all over the world and provide a base for all dairy products.

It nourishes human body by providing it necessary nutrients required for sustaining the life (Guetouache et al., 2014). Consumption of dairy foods recommended in daily diet patterns as it prevent some chronic diseases including cancer (Park et al., 2009). It has been estimated that 90% of total milk products depends on these traditional milk products, because it is the more efficient way to make profit than selling the whole milk (Singh et al., 2015). The annual gross production of milk in Pakistan is 57,890 million litters (Anonymous, 2018).

One the most favorite milk based product is rabdi out of various traditional products i.e. jalebi, khoya, barfi, gulab jamun, basundi, dhoda, sohn halwa, and rabdi (Ghayel et al., 2013). Rabdi is a traditional milk product and considered as a delicacy in Pakistan as well as in India. It is sweetened in taste and appeared whitish brown in colour with slightly cooked flavor. Rabdi has unique chewy texture due to immersed malai (cream). It has very high demand in festivals and traditional celebrations. Along with it is very nutritious, also it has very refreshing effect in hot season (Aneja et al., 2002). www.ijeid.com

Rabdi manufacturing process consist of simmering of milk till 1/5th or 1/8th of milk remains then sugar is added according to the initial volume of milk (Pal, 2000). It includes thin layers of cream which come over the surface by heating. It was observed that there is very void variation in clotted cream layer and sweetened condensed milk ratio and it is very crucial for grainy and unique texture of rabdi (Chopde et al., 2013). Rabdi making is a labor, time and energy intensive process and confined to small batches 5 to 10 liters of milk (to reduce the milk volume and gives 50 to 55% final concentration of total solids (Dande et al., 2011; Chauhan et al., 2014) and it was observed that Chopde et al., (2016) were significantly increase the efficiency of the rabdi making process by using conical process vat (CPV) and scraped surface heat exchanger (SSHE). Rabdi is a rich source of milk fat and protein and give instant energy (Sharma et. al. 2009). Among different types of available rabdi one is diabetic rabdi with no cane sugar and the second is flavoured rabdi with date palm syrup (Ghayal et al., 2015; Kaushik et al., 2016). The shelf life of rabdi is 16 hours at ambient temperature and up to 18 days at refrigeration temperature (Khaskheli et al., 2008).

Rabdi doodh, an intermediate product in the process of rabdi making, is also made on the principles of rabdi but is relatively less concentrated than rabdi. Rabdi doodh is a sweetened drink as compared to rabdi. Though rabdi doodh is less concentrated but it is equally nutritious like rabdi and give all milk nutrients and minerals without much heat losses. It has slightly brown color, sweetened cooked flavor, caramelized aroma and should be chilled before serving. Generally rabdi doodh is made by local sweet confectioners (halwais) on small scale. Owing to no standards has been set for its quality and composition, rabdi doodh is different in its quality from one confectioner to other. Unhygienic and non-standardized approach made it confined to small scale and limited to local halwais. It involves extensive labor and time which makes its cost very high. Since no approach and steps has been taken to make it standardized and optimized with uniform quality and flavor, this study was aimed to achieved the following objectives:  To develop a well-balanced recipe of rabdi doodh  To improve and assess the shelf life of rabdi doodh

MATERIALS AND METHODS Preparation of rabdi doodh Rabdi doodh was prepared by simmering of milk having 4.5% fat and average 12.5% total solids in Dairy

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Development and optimization of traditional product Rabdi doodh and its quality assessment Technology Laboratory, NIFSAT, University of Agriculture Faisalabad, according to method reported by Singh and Singh, (2015). Three treatments were made R1 (20% TS), R2 (25% TS) and R3 (30% TS) on the basis of total solids concentration. The product packed in Pet bottles and stored at 4°C for 28 days storage and chemical analysis done after 7 day’s interval.

Sensory evaluation The sensory attributes was evaluated by a panel of untrained 8 judges using 9 point hedonic scale. The sensory attributes evaluated were taste, aroma, color and overall acceptability (Chopde et al., 2016).

Chemical analysis The chemical analysis done for assessment of storage quality of rabdi doodh. The %fat was determined by Gerber method and protein was determined by Kjeldhal’s method (AOAC. 2006). The pH was determined by digital ph meter, lactose and acidity was analyzed by Fehling’s and titrimetric method described in AOAC, (2006) respectively.

Statistical analysis The experiment was laid out according to CRD arrangements with four replications of each treatment.

Data was collected and statistically analyzed and treatment means were compared using software statistix 8.1 (Statistix corporation, Tallahassee, Florida, USA) (Montgomery, 2008).

RESULTS AND DISCUSSION Sensory evaluation Analysis of variance for sensorial attributes showed that different treatments significantly affect the colour, taste, aroma and overall acceptability of rabdi doodh (Table 2).

The sensorial score obtained for colour was highest in R3 samples 7.87 and lowest in R1 samples 6.0 and significantly different in all treatments proved by

Randhawa et al

statistical data. The improvements in colour affirmed by Jain et al., (2013) who observed increased in colour of dairy product lal peda from 7.8 to 8.7 by increasing total solids of the product 69.9% to 71.3%. It was observed that maximum score for taste acceptability found in treatment R3 (7.87) and least acceptability was shown by treatment R1 (6.87) and the results was affirmed by Gautam et al., (2013) as they observed significant increase in taste of channa kheer from 6.5 to 8.0 as total solids increased from 86.5% to 88.0%. Sensorial score for aroma of rabdi doodh was observed maximum 7.5 in R3 and minimum 6.25 score was found in R2. The aroma of product may be increased by increasing concentration of total solids and the results obtained from this study were affirmed by Banjare et al., (2015) who reported best aroma score (8.4 to 7.6) at first day when total solids was higher than last day of storage. It was observed that the maximum sensory score (7.75) obtained for overall acceptability was found in R3 treatment while minimum score 6.41 was observed in R1. The same improvement in overall acceptability was reported by Dhuma et al., (2018) who observed highest score (7.90 to 8.56) for overall acceptability of novel rabdi prepared with fig syrup. Analysis of variance for sensorial attributes showed that different treatments significantly affect the colour, taste, aroma and overall acceptability of rabdi doodh. Statistical data proved that overall means of R1, R2 and R3 for sensory evaluation were significantly different from each other.

Chemical analysis The chemical analysis of rabdi doodh for fat revealed that %fat was significantly decreased form (9.17 % to 8.2 %) in R3, (7.80 % to 7.15 %) in R2 and (6.27 % to 5.52 %) in R1 form day 0 to 28 respectively. Maximum fat content was observed in R3 (9.17%) at day 0 and minimum fat content was found in R1 (5.52%) at day 28.

The reduction in fat content was observed higher in R3 and R1 than in R2.

Table 1: Effect of different treatments and storage days on chemical properties of rabdi doodh.

Treatments No. of Days Overall Mean 0 7 14 21 28 6.27±0.08 6.17±0.04 6.05±0.08 5.80±0.04 5.52±0.04 5.96±0.04 Fat (%) R1 7.80±0.07 7.82±0.02 7.62±0.02 7.32±0.04 7.15±0.02 7.54±0.02 R2 9.17±0.04 9.12±0.02 9.12±0.02 8.82±0.04 8.20±0.04 8.89±0.04 R3 7.75±0.05 7.70±0.02 7.60±0.04 7.31±0.01 6.95±0.05 Overall Mean 6.12±0.03 6.02±0.04 5.90±0.03 5.61±0.02 5.10±0.05 5.75±0.04 Lactose (%) R1 7.26±0.02 7.10±0.02 6.77±0.01 6.75±0.02 6.18±0.01 6.81±0.02 R2 8.35±0.03 8.01±0.04 7.89±0.05 7.19±0.06 7.19±0.03 7.62±0.04 R3 7.24±0.03 7.04±0.05 6.84±0.02 6.52±0.01 5.99±0.03 Overall Mean 5.16±0.04 5.01±0.03 5.01±0.03 4.95±0.01 4.86±0.04 5.00±0.03 Protein (%) R1 6.28±0.05 6.15±0.02 6.15±0.04 5.97±0.04 5.84±0.02 6.08±0.01 R2 7.90±0.01 7.75±0.04 7.74±0.05 6.98±0.06 6.88±0.01 7.45±0.04 R3 6.45±0.04 6.31±0.05 6.30±0.01 5.97±0.03 5.86±0.02 Overall Mean 6.85±0.04 6.69±0.05 6.54±0.06 6.33±0.04 5.69±0.03 6.42±0.02 pH R1 6.73±0.03 6.67±0.02 6.54±0.01 6.24±0.07 5.69±0.02 6.37±0.03 R2 6.79±0.02 6.69±0.01 6.51±0.03 6.21±0.07 5.66±0.01 6.37±0.02 R3 6.79±0.03 6.68±0.07 6.53±0.03 6.26±0.05 5.68±0.02 Overall Mean 0.06±0.07 0.08±0.04 0.14±0.05 0.26±0.02 0.44±0.07 0.20±0.01 TA (%) R1 0.06±0.03 0.08±0.02 0.12±0.04 0.28±0.04 0.49±0.03 0.20±0.05 R2 0.06±0.02 0.09±0.06 0.15±0.03 0.26±0.05 0.50±0.02 0.21±0.03 R3 0.06±0.02 0.08±0.04 0.14±0.03 0.27±0.05 0.50±0.04 Overall Mean www.ijeid.com

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International Journal of Excellence Innovation and Development ||Volume 2, Issue 1, Jan. 2019||Page No. 021-024||

Treatments R1 R2 R3

Table 2: Effect of different treatments on sensorial attributes of rabdi doodh.

Mean (/9) Colour Taste Aroma Overall acceptability 6.0±0.43 6.87±0.54 6.25±0.58 6.41±0.37 6.87±0.65 7.0±0.38 6.37±0.45 6.70±0.42 7.87±0.27 7.87±0.24 7.50±0.76 7.75±0.66

A similar trend was observed in the rabdi samples as the fat content was decreased (from 20.58 % to 19.22 % and 21.58 % to 20.22 %) at both ambient and refrigeration temperatures reported by Singh and Singh, (2015).

It was observed that lactose content of the product significantly reduced from day 0 to 28. The lactose content was reduced form (8.35 % to 6.67 %) in R3, (7.26 % to 6.18 %) in R2 and (6.12 % to 5.10 %) in R1 from day 0 to 28 respectively. The maximum lactose content was found in treatment R3 8.35% at day 0 and minimum was observed in treatment R1 5.10% at day 28. There were similar reductionof lactose content decreased from 13.65 % to 13.29 % in basundi may be caused by conversion of lactose into basic units’ glucose and galactose reported by Gaikwad and Hembade, (2013).

It was observed that maximum protein content was fount 7.9% in R3 at day 0 and minimum was observed 4.86% in R1 at day 28. The protein content of rabdi doodh was significantly decreased from day 0 to 28 as it reduced from (7.9 % to 6.88 %) in R3, (6.28 % to 5.84 %) in R2 and (5.16 % to 4.86 %) in R1. The reduction of protein content in this study affirmed by Singh and Singh, (2015) as they observed protein content decreased from (10.58%) to (8.50%) in rabdi during 0 to 12 days of storage at refrigeration temperature.

the product and combined action of treatments and number of days. The pH and titrable acidity of the product was significantly (p≥0.001) affected by different number of days but it was non-significantly (p≤0.05) affected by different treatments and combined action of both evident from analysis of variance.

CONCLUSION The sensory and chemical parameters results showed the treatment R3 scored highest among oher two treatments R2 and R1 in terms sensorial overall acceptability along with good keeping quality of the product at 4°C. During storage of rabdi samples it was observed that the physiochemical parameters was changed least but significantly from day 0 to 14 and the changes were at faster pace after 14 day at refrigeration temperature. The chemical parameters i.e. fat, lactose, protein and pH were significantly reduced while total acidity was significantly increased from day 0 to 28.

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The significant increase in titrable acidity observed from day 0 to day 28 of storage for all three treatments. The average TA values significantly increased from (0.06 % to 0.50 %) in R3, (0.06 % to 0.49 %) in R2 and (0.06 % to 0.44 %) in R1 from day 0 to 28 respectively. The values for TA was observed higher in R3 throughout the storage period. The increased in TA may be caused by increase in microbial activity in product reported by Banjare et al., (2015) in peda as TA was increased from 0.41% to 0.50 % at day 1 to 12, and Kaushik et al., (2016) observed in rabdi the TA was increased from 0.054% to 0.44% at 0 to 20 respectively.

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