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Optimization of Khoa and Tikhur Mix for Preparation of Khoa-Jalebi Sweet

Research Article Open Access
Rewa Kumari*, Shrivastava SL and Mishra HN
Agricultural and Food Engineering Department, Indian Institute of Technology, Kharagpur-721302, India
*Corresponding author: Rewa Kumari
Agricultural and Food Engineering Department
Indian Institute of Technology
Kharagpur-721302, India
E-mail: rewakumar11@gmail.com
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Received June 21, 2012; Published November 24, 2012
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Citation: Kumari R, Shrivastava SL, Mishra HN (2012) Optimization of khoa and tikhur Mix for Preparation of Khoa-Jalebi Sweet. 1:469. doi:10.4172/scientificreports.469
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Copyright: © 2012 Kumari R, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Abstract
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Khoa-Jalebi Sweet (KJS) is a unique and popular khoa based sweet of central India, prepared from khoa and tikhur. For optimizing KJS, the proportion of tikhur vis-Ã -vis khoa and soaking time of tikhur was varied from 20 to 60 g/100 g of khoa and 2 to 10 h respectively using central composite rotatable design. The raw material tikhur was analyzed for Water Absorption Capacity (WAC); Khoa-Jalebi batter was analysed for Apparent Viscosity (AV) and Yield Stress (YS), and the prepared jalebi samples were evaluated for fat content, Sugar Syrup Absorption (SSA), hardness and sensory parameters. All these parameters were significantly (p<0.05) influenced by varying tikhur in relation to khoa. The effect of soaking time on fat content, colour, taste and Overall Acceptability (OA) scores of KJS was non-significant (p< 0.05) but other parameters were significantly influenced by it. Optimization by response surface methodology showed that 47 g of tikhur per 100 g khoa and soaking time of 5.9 h gave desirability index of 0.79 and OA score of 7.70 out of 9.0 on hedonic scale which was comparable with market sample showing OA of 7.67.
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Keywords
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Khoa-Jalebi; Tikhur content; Hardness; Viscosity; Sensory scores
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Introduction
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Indian dairy sweets are ubiquitous part of every festival, wedding, religious ritual and are symbol of joy and pride. The appeal and satiety they offer makes them ambrosia for consumers. Though the market of variety of traditional dairy sweets is widespread in India, they have not been commercialized due to predominance of unorganized sector and because of the constraints regarding their shelf life. Indian dairy sweets are largely made from two base materials chhana and khoa and it is estimated that about 5.5% of total milk production is utilized for khoa making in India [1,2]. Jalebi is an Arabian sweet that is famous for its distinct spiral shape and sweet, chewy taste. Though it is an Arabic dish, but it is largely popular in India, Pakistan and Bangladesh. KJS is a unique khoa based sweet of central India which is relished as snack in the evening time and as breakfast item. It is observed that KJS is consumed on religious fasting days such as Ekadashi (spiritually beneficial day) and other festivals when fasting is observed by people [3]. Pagote and Rao [4] collected information on Khoa-Jalebi sweet from Nagpur, Nasik, Wardha and Indore cities in Maharashtra and Madhya Pradesh states of India and observed that the market of khoa-jalebi sweet was not distributed uniformly in cities. It is generally round or oval shaped, having thick coils and golden to dark brown colour and has caramelized sweet taste.
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The raw materials used for making KJS are khoa and tikhur. Khoa is a heat desiccated milk product prepared by vigorously boiling and stirring milk continuously to attain a moisture level of about 30-35 %. Tikhur (Curcuma angustifolia) is a herb with medicinal properties. In English, it is called Wild or East Indian arrowroot. It is widely grown in Chhattisgarh and Madhya Pradesh states of India. Medicinally, it is a cardiac tonic, diuretic, antipyretic and reduces burning sensation [5]. It is reported that Abujhmaria tribes use fresh rhizomes of tikhur to prepare starchy flour, which has a medicinal potential and is considered good for peptic ulcer patients, as it provides cooling effect [6]. The preparation technique of KJS including the proportion of ingredients, batter making, frying and soaking in sugar syrup etc. varied significantly from sweet makers shop to shop. As such not much literature is available on standardization of constituents of KJS. The present investigation was taken up for optimizing the ratio of tikhur in relation to khoa and soaking time of tikhur for uniform and overall acceptability of KJS using Response Surface Methodology (RSM). According to Montgomery [7], RSM is a collection of mathematical and statistical techniques useful for modeling and analysis of problems in which a response of interest is influenced by several variables and the objective is to optimize this response. It is an effective optimization tool which has been previously used for optimizing various food products such as idli [8]; jackfruit sauce [9] and jilebi [10].
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Materials and Methods
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For preparation of KJS, cow milk, sugar, tikhur and ghee were procured from the local market of IIT Kharagpur. Cow milk (3.5 % Fat and 8.5 % Solid-not-Fat) was converted to khoa by open pan method and tikhur, which is dry and white in color, was soaked in water and filtered before adding in khoa. Moisture, fat, protein and ash content of khoa and tikhur were determined using procedures specified in [11]. Lactose in khoa and KJS was determined by the method provided in [12]. Starch content in tikhur was determined [13].
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Preparation of Khoa-Jalebi sweet
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The flow chart for the preparation of KJS is shown in figure 1. Khoa and soaked tikhur were properly mixed in wet mixing jar for 15-30 sec. Small quantity of water was added if the batter was too tight otherwise the mixture was taken in a special woven jalebi making cloth having an opening of 1 cm. The batter was poured in hot ghee in circular frying pan having diameter of 27 cm. The batter was given a round shape and one knot in ghee and fried for 5 to 4 min at medium flame (160-170°C); 4 to 5 jalebi samples were fried at a time. The fried jalebi was soaked in sugar syrup of 65°C Brix for 5 min.
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Figure 1: Process and material flow chart of khoa-jalebi preparation.
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Experimental design
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A central composite rotatable design was constructed to explain the combined effects khoa:tikhur ratio and soaking time of tikhur using Design Expert 7.0.0 version. The ratio of khoa:tikhur was varied from 100:20 to 100:60 w/w and soaking time was in the range of 2 to 10 h as shown in table 1. Tikhur was soaked in 1:6 ratio with water at room temperature. Maximum and minimum predictor values were chosen after carrying out preliminary trials.
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Table 1: Experimental design for KJ optimization in actual levels 22 of variables.
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Water absorption capacity of tikhur was recorded by weighing tikhur before and after soaking and reported as g/g. Fat content of Khoa-Jalebi was determined by using moisture free samples of KJS for Soxhlet method. Sugar Syrup Absorption (SSA) of KJS was measured immediately after frying, was kept in syrup and the amount of syrup absorbed in the product by weighing before and after soaking and expressed as g/g. The hardness of KJS was measured using Brookfield Engineering Texture Analyzer (CT 3 Model). Hardness value was considered as mean peak compression force and expressed in grams. The settings used were pre-test speed of 2.0 mm/s, test speed 1.5 mm/s, post-test speed 1.5 mm/s, trigger load 15 g and target value 5.0 mm.
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Apparent Viscosity (AV) of the batter samples were determined using Anton Paar Rheometer (MCR 301 Model, Germany) with cone and plate geometry of 50-1 specification having d= 0.102 mm by [10]. Sample batters were subjected to varying shear rates ranging from 0.1s-1 to 100s-1 with 29 measuring points. The AV was reported at shear rate of 50s-1. YS was determined using controlled stress measurement technique by generating shear-stress/shear-rate data up to a shear stress of 70 Pa with 40 measuring points in 120 sec [14]. However, initially samples were sheared at a shear rate of 30s-1 followed by relaxation for 30 sec. KJS samples were analyzed for colour, taste and OA using 9-point hedonic scale (1=dislike extremely; 5=neither like nor dislike; 9=like extremely) by a panel of semi-trained members (n= 15) [15].
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Statistical analysis
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All the responses were subjected to analysis of variance and multiple regression analysis using Design Expert 7.0.0 version software. The fitting was done to a second order model for each response. This model can be expressed with the coded variables (T and St) with the following equation:
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Y=b0+b1*T+b2*St+b3*T *St+b4*T2+b5*St2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â (1)
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Where Y is the predicted response, b0 is the offset term, b1 and b2 are linear term, b3 is interaction term and b4 and b5 are squared terms, T is tikhur content (%) and St is soaking time (h).
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Results and Discussion
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The proximate values of the ingredients are shown in (Table 2). The average moisture content of khoa and tikhur was 30.4 and 1.7% respectively. Fat and protein contents of tikhur were negligible and it contained 98.0% starch whereas khoa contained 22.8 and 17.3% fat and protein, respectively.
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Table 2: Proximate analysis 1 of khoa and tikhur.
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The effect of different tikhur levels and soaking time on WAC, fat content and SSA are shown in figure 2 and condensed analysis of variance is shown in (Table 3). Tikhur level and soaking time had significant (p<0.05) effect on WAC and were positively correlated with increasing WAC. As the tikhur content was raised from 20 to 60 g in 100 g of khoa WAC increased from 1.88 to 2.33 g/g. Fat content of KJ decreased significantly from 23.44 to 9.42% because khoa content in the mixture batter was replaced by increasing tikhur level (from 20 to 60 g) and tikhur is devoid of fat. Soaking time had no significant effect on fat content of KJS. SSA increased significantly (p<0.05) with the increase of both the tikhur content and soaking time. For 20 g of tikhur, SSA was 1.49 g/g which rose to 1.65 g/g for 60 g of tikhur vis-Ã -vis khoa at 6 h of soaking time implying more porous and void structure of KJS in which more sugar syrup could be absorbed.
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Figure 2: Response surface plots showing the effect of tikhur content and soaking time on a) WAC, b) Fat content and c) SSA of khoa-jalebi.
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Table 3: Condensed analysis of variance for WAC, fat content and 63 SSA in khoa-jalebi.
*Significant p<0.05, **Significant p<0.01, T= Tikhur and St= Soaking time.
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Figure 3 depicts the effect of different tikhur levels and soaking time on AV and YS of batter and hardness of the prepared KJS. Batter viscosity determines the way batter flows in the form of product before it enters the fryer. The ingredients of the batter and their chemical nature affect flow characteristics of the batter. The apparent viscosity of flour-based batters was positively correlated with batter adhesion [16]. Khoa being soft and semi-solid needs proper mixing with tikhur to give smooth and homogenous batter so that while straining through cloth characteristic shape can be given with ease. Any lump will impair the structure of jalebi. Too viscous a batter may produce uneven and lumpy crusts [17]. As the level of tikhur content in the batter mix was increased from 20 to 60 g/100 g of khoa for different soaking time, apparent viscosity reduced from 14.73 to 7.86 Pa. Higher apparent viscosity indicated difficulty in flow and lower values implied ease of flow. Similar trends were observed for YS which lowered by 59.3 per cent from 50.05 to 20.80 Pa. This is because as the khoa level was lowered the flowability of the batter improved. Both tikhur content and soaking time affected AV and YS significantly (p<0.05). The experimental yield stress of maida jalebi batter was reported to be varying between 0.31 and 15.76 Pa [10]. Hardness increased significantly (p<0.05) from 382 to 620 g due to higher amount of tikhur and lower amount of khoa in the batter. Higher level of tikhur and increased soaking time was positively correlated with hardness of KJS.
 
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Figure 3: Response surface plots showing the effect of tikhur content and soaking time on a) AV, b) YS and c) hardness of khoa-jalebi.
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Second order quadratic equations were fitted and coefficients of polynomial are reported in (Table 4).
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Table 4: Condensed analysis of variance for apparent viscosity, yield stress and hardness in actual values.
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Tikhur content significantly changed the colour, taste and OA scores (p<0.05) as shown in figure 4. However soaking time had no significant effect on sensory parameters. Multiple regression equations were generated for sensory scores and terms with negligible values were ignored as shown in table 5. Increasing or decreasing tikhur and soaking time from the centre point reduced the taste and overall acceptability scores. For selection of optimum ratio of tikhur vis-Ã -vis khoa and soaking time in KJS, simultaneous optimization of several responses was done. For optimization of KJS all the sensory parameters were maximized and yield stress was minimized as higher yield stress imposed problems in giving smooth batter shape whereas other independent variables were kept in range. In order to search a solution maximizing multiple responses, the goals are combined into an overall composite function, D(x), called the desirability function [18], which is defined as:
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Figure 4: Response surface plots showing the effect of tikhur content and soaking time on a) colour, b) taste and c) OA of khoa-jalebi.
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Table 5: Condensed analysis of variance for sensory responses (colour, taste and OA) in actual values.
*Significant p<0.05, **Significant pTikhur and St= Soaking time
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D (x) = (d1*d2*……..*dn)1/n                                                        (2)
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The desirability function can be used to combine multiple responses into one response called the “desirability function” by choice of value from 0 (one or more product characteristics are unacceptable) to 1 (all product characteristics are on target). Optimization of KJS for different quality factors by RSM gave 47 g of tikhur/100 g khoa and 5.9 h soaking time (Table 6). Optimization yielded the desirability score of 0.79. The optimized product was prepared and compared with its predicted values and the model was proven to be adequate.
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Table 6: Optimization criteria for different process variables and responses in khoa-jalebi.
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The optimsed sample was compared with market sample for chemical constituents, physical characteristics such as weight, diameter, thickness and colour values (Table 7). Optimized product had higher moisture, fat, protein, ash content than market sample but carbohydrate content of lab made KJS sample was lower than market sample which could be attributed to better quality of ingredients taken for experiment. Market samples were also significantly darker than lab made samples. The Overall Acceptability (OA) score was 7.70 for the optimized samples compared to 7.67 for the market sample.
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Table 7: Comparison of quality attributes of laboratory made KJ samples with that of market sample.
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Conclusion
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The RSM approach was used to optimize the tikhur level (g/100 g khoa) and soaking time (h) by using WAC, fat content, SSA, AV, YS, hardness and sensory scores as dependent variables. Tikhur level had the maximum significant (p<0.05) influence, whereas the effect of soaking time was comparatively less on the quality attributes of KJS. Results also showed shear thinning behavior of batter samples. Optimization by response surface methodology showed that 47 g of tikhur vis-Ã -vis khoa and soaking time of 5.9 h gave desirability index of 0.79 and OA score of 7.70 which was comparable with market sample showing OA of 7.67.
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Acknowledgements
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The authors are sincerely thankful to the Department of Biotechnology, Govt. of India New Delhi for financial assistance.
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References
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