Utilization of Jamun seed powder in composite cake formulation

The study is concerned with the evaluation of the nutritional and functional properties of Jamun seed powder (JSP) extracted from fresh Jamun and to develop cakes by incorporating JSP with wheat flour (WF). The chemical analysis showed that JSP had 6.30% moisture, 6.24% protein, 2.19% ash, 1.18% fat, 84.09% carbohydrate and 371.94 Kcal energy/100 g of powder whereas WF contained 12.90% moisture, 11.00% protein, 1.35% ash, 1.50% fat, 73.01% total carbohydrate and 349.54 Kcal energy/100 g of powder. Four cake samples were prepared by using different proportion combination of WF and JSP such as A (100% WF), B (90% WF and 10% JSP), C (80% WF and 20% JSP) and D (70% WF and 30% JSP). The nutritional components of four cake samples gave the range of moisture 16.92-25.56%, protein 6.34-8.56%, ash 1.50-2.60%, fat 16.01-22.42% and total carbohydrate 41.9658.13%. Weight (g) of processed cakes were increased whereas other physical attributes such as volume, height, specific volume were decreased due to supplementation of JSP. The increased level of JSP powder substitution changed the crust color of cakes from light brown to blackish and also changed the crumb color from brownish to reddish. Sensory evaluation indicated that the sample B (10% JSP and 90% WF) was the most acceptable by the panelists than those of other cakes. Above all, the study gave an indication that Jamun seed powder can be used as a good replacement of wheat flour in production of cakes which can help to get higher energy, mineral and carbohydrate. Article history: Received: 03 July 2019 Accepted: 29 September 2019 Published: 31 December 2019


Introduction
Jamun (Syzygium cumini) also known as Syzygium jambolanum, Eugenia jambolanum and Eugenia cumini is an evergreen tropical tree in the flowering plant family Myrtaceae and is native to Bangladesh, India, Nepal, Pakistan, Sri Lanka, the Philippines, and Indonesia (Razoanul et al., 2017). The fruit is a good source of iron, minerals, sugars and proteins. Besides its use as dessert fruit, Jamun is used for preparation of delicious beverages such as jellies, jam, squash, wine, vinegar etc. (Devi et al., 2016). According to statistical data of BBS (2015), the annual production of Jamun is approximately 51302 metric tons in Bangladesh from 386 acres land in the year 2013-2014 in which increasing production rate of Dhaka (approximately 13999 metric tons) is bigger than other division.
A full Jamun consist of its edible part, seed coat and kernel. The edible part of whole Jamun fruit is around 75%. 83.7% moisture, 0.7% protein, 0.3% fat, 0.9% crude fiber, 14% carbohydrate and 0.4% ash was found in edible part of Jamun (Chaudhary and Mukhopadhyay, 2012). The Jamun seed contains 6.63% protein, 0.66% lipid, carbohydrate 75.4% and insoluble dietary fiber 1.32%. Jamun seed powder is good sources of vitamin-C and vitamin-B complex as well as dietary fiber, potassium, iron and they are low in fat and cholesterol. It also contains some essential minerals such as potassium, calcium, sodium, magnesium and phosphorus (Priyanka and Mishra, 2015).
Jamun contains high level of anthocyanins and other phenolic compounds, mainly flavonols and ellagitannis, which contribute to its high antioxidant capacity and other biological activities (Kannan and Puraikalan, 2016). The phenolic composition and concentration are known to be influenced by genetics, growing condition and maturation. Phenolic compounds found in Jamun include anthocyanins, gallic acid, folic acid, tannis, ellagic acid, ellagitannis and cyanidins (Huang et al., 2012). It contains oil which is rich in omega-3 (alphalinolenic acid) and omega-6 fatty acid (linoleic acid) as well as carotenoids and ellagic acid. Additionally, the seeds are a great source of antioxidants (Shahnawaz et al., 2010).
Jamun fruits are universally accepted to be very good for medicinal purposes especially for diabetes because of its effect on the pancreas (Joshi, 2001). The fruit, its juice and the seed contain a biochemical called 'Jamboline' which is believed to check the pathological conversion of starch into sugar in case of increased production of glucose. Jamun seeds are known for their medicinal characters to cure diabetes, diarrhoea, dysentry and blood pressure (Chopra et al., 1956). Many researchers used JSP for replacement of wheat flour to produce different bakery products. Thorat and Khemnar (2015) worked with the whole WF and JSP blends in the preparation of functional cookies to improve the quantity and quality of protein, carbohydrate, and fiber content. They recommended that cookies can be produced by incorporating JSP in WF up to 20% to get suitable color, flavor, texture and overall acceptability.
Although wheat flour is a good source of calories and other nutrients, but the price of wheat flour is increasing day by day due to multipurpose uses. Mixing of JSP with WF, which increases nutritional quality, shelf life and also the excellent taste of preparing cake could be a good alternative to WF. Only Jamun flesh is utilized but large amount of Jamun seed being discarded every year. So, it will be a unique technique to prepare different value added products by mixing JSP and other ingredients for cakes, cookies, biscuits preparation. It can be used to develop nutritionally enriched bakery products. Keeping above views in mind, the study was carried out to fulfill the following objectives: (i) to compare the functional and chemical properties of JSP with WF and (ii) to assess physicochemical and organoleptic properties of developed cakes using various concentration of JSP.

Preparation of JSP
Fresh Jamuns were collected from the local market of Mymensingh. Collected Jamuns were washed and pulped to get the Jamun seed and rinsed immediately. Then the seed coat was manually removed to get the Jamun seed. These Jamun seeds were used for powder preparation. The seeds were washed properly to remove any adhering material. Then the Jamun seed were dried for 5-6 hours at 70˚C by using a mechanical dryer. The dried materials were grinded in lab grinder into flour and transformed into a very fine powder by sieving. The powdered sample was then stored in polybag and kept in desiccator for future using.

Formulation and preparation of JSP supplemented cakes
The formulation of JSP supplemented cakes for the present research is given Table 1 and the development method was as follows: All of the ingredients were weighed separately and were mixed in a bowl. Eggs were taken in the beater bowl and was beaten until it formed foam. Then sugar was added to it and was beaten again until it mixed properly. Then the flour mixture, baking powder, milk powder and salt were poured into the bowl with a spoon and the mix was beaten again until complete mixing occurred. Subsequently, flavor and oil was added to the mixture and was beaten to form a suitable mix for cake formulation. After waiting for 30 minutes and the mix was put in mould and was baked at 160˚C for 40 minutes.

Chemical analysis
Moisture and crude fiber contents were measured by the methods described in AOAC (2012) whereas ash, protein and fat contents were determined by the methods described by Ranganna (2005). Carbohydrate content was determined as total carbohydrate by following Pearson (1976) by subtraction method. Energy value was calculated as total energy per 100g as per method of Birch et al. (1980). Triplicate determinations were performed for all analysis.

Functional properties analysis
The JSP and WF were analyzed for functional properties as like bulk density, water absorbing capacity, oil absorption capacity and swelling index by using the method described by Okaka and Potter (1977), Khetarpaul et al. (2005), Sosulski et al. (1976) and Lin et al. (1974) respectively.

Analysis of physical properties of developed cakes
Weight of cakes was measured as average of values of four individual cakes with the help of digital weighing balance. The volume (cm 3 ) was measured by rapeseed replace method described in the (AACC, 1983). The specific volume was obtained by dividing the volume of cakes by their weights. Height of cakes was measured by using scale and an average value was taken.

Sensory evaluation
The consumer's acceptability of developed cakes was evaluated by a testing panel of 15 panelists. The hedonic rating test was used to determine the acceptability. The panelists were chosen from different social status. The panelists rated their acceptability of the product on a 01-09 point hedonic scale. The scale was arranged such that 9= like extremely, 7= like very much, 6= like slightly, 5= neither like nor dislike, 4= dislike slightly, 2= dislike very much and 1= dislike extremely.

Statistical analysis
The scores given by the panelists were analyzed by SAS (Statistical Analysis System, version 8.2). Fisher's LSD Multiple Range Test was used to detect mean differences at 5% level of significance.

Nutritional comparison between JSP and WF
The comparative analysis of the proximate composition and energy content of the JSP and WF is shown in Table  2.

Comparison of functional properties between JSP and WF
Functional properties of JSP and WF such as bulk density, water absorption capacity, oil absorption capacity and swelling index are shown in Table 3.  Table 3, it is seen that the bulk density of JSP (0.71 g/ml) was higher than WF (0.66 g/ml) which indicates that JSP had higher weight per unit volume than WF. Das (2017) and Suresh and Samsher (2013) found that the bulk density of WF as 0.58 and 0.762 g/ml respectively. The water absorption capacity indicated that JSP absorbed more water than WF to form a standard dough. From research findings of Lee et al. (2001) it was found that dough other than wheat flour had higher water absorption rate than that of wheat flour. From the table, it is also notable that WF absorb more oil than JSP which is similar to the results found by Das (2017), who observed that mango kernel flour has comparative lower oil absorption capacity than WF. The calculated value of swelling index of JSP was 1.344 and the swelling index of WF was 3.404. The swelling index of WF was higher than JSP. Shariful et al. (2015) found that the swelling index of jackfruit flour was 1.46 while Menon et al. (2014) reported the swelling index value as 4.00 for WF. From the above study, it can be said that the functional properties of the JSP and WF varied from each other and this variation might be due to difference between the category of two sample, particle size of flours and milling process, nutritional properties and chemical structure as well (Das, 2017).

Storage stability of JSP
The existence of any product without any change in the quality can be analyzed by the process of storage study. Moisture is one of the important parameter which interferes the quality of any food product during storage. The storage stability in terms of moisture gain by storing the JSP at room (30˚C) and refrigeration temperature (5˚C) was investigated to get the change in moisture content by gravimetrical determination. JSP with initial moisture of 6.30% was packed in the single layer polythene and kept in laboratory at room temperature and refrigeration temperature and the obtained changed is shown in Figure 1. The study showed that the moisture uptake by JSP were increased continuously throughout the investigation period for both the storage condition. The moisture was increased both at room and refrigeration temperature. The increasing rate of moisture was higher at room temperature than refrigeration temperature but up to two months of storage, no deterioration was occurred or no visible changes were observed in quality of JSP. However, there was a gradual increase in moisture level over the period of extended life, higher increase in the samples stored at ambient temperature. The result was consistent with Reddy (2011) who observed that sorghum flour could be stored only for 28 days, further more imposed in loss of its functional properties. The extended life of JSP beyond the period of 2 months due to its lowest fat value 1.18% compared to sorghum flour 1.90%.

Chemical composition formulated cakes
The formulated cakes were analyzed for their chemical components such as moisture, protein, ash, fat and total carbohydrate content and the values are presented in Table 4. Also the energy content per 100 g of sample is depicted on Table 4.

Protein
The protein content of different cake samples such as A (100% WF), B (90% WF and 10% JSP), C (80% WF and 20% JSP) and D (70% WF and 30% JSP) were 8.56, 7.20, 7.04 and 6.34% respectively. The protein content of control sample (100% WF) was lower than the other samples. Khan et al. (2016) found that the protein content of composite cakes were 6.91 to 8.32% and the protein content of control sample was found 6.21%. Das (2017) was found that the protein content of composite flour was 7.24 to 6.92%). The protein content of developing composite cakes were more or less similar by other researchers. Protein content of the developed cakes varied due to variation of protein content of the flours. Increasing of temperature results in breakdown of protein and sugar in foods, which subsequently causes denaturation of protein (Pascual et al., 2002). This protein denaturation may also responsible for the difference of protein content (Akter and Alim, 2018).

Ash
The ash content of the cake samples were in the range of 1.50 to 2.60%. From the Table 4, the sample D (70% WF and 30% JSP) gave the highest amount of ash as 2.60%, followed by sample B (90% WF and 10% JSP) as 2.08%, sample C (80% WF and 20% JSP) as 2.35% and sample A (100% WF) as 1.50%. The ash content of the cake samples increased with increased amount of JSP. This might be due to JSP contain higher amount of ash than wheat flour.

Fat
From the Table 4, the highest fat content of the sample A (100% WF) was found to be 22.42% and the lowest fat content of the sample D (70% WF and 30% JSP) was as 16.01%. The fat content of cake samples were decreased in addition of different percentage of JSP. Akter and Alim (2018) found the fat content of composite cake was 25.63 to 32.25% prepared from wheat-potato-peanut. From the above result, the fat content of composite samples were more or less similar to other researchers. This might be due to JSP contain lower amount of fat than wheat flour.

Total carbohydrate content
The total carbohydrate content of the sample D having 70% WF and 30% JSP was the highest among the samples while the 100% WF containing sample had the lowest carbohydrate content. The variation in the carbohydrate contents among cakes samples may addition of different percentage of JSP. The variation in the total carbohydrate contents among cakes samples may result from the difference in the amount of protein, fat, ash and moisture content.

Energy
The energy content of control cake (100% WF) was 403.86 Kcal/100g and the energy content of other cake samples such as B (90% WF and 10% JSP), C (80% WF and 20% JSP) and D (70% WF and 30% JSP) were 403.73, 399.72 and 401.97Kcal/100g. Kiin-Kabari and Banigo (2015) found that the energy values of cakes prepared by plantain flour and Bambara groundnut protein concentrate to be range of 328.2 to 359.5 Kcal/100g of cake. The energy content of JSP were decreased due to the lower fat content.

Physical properties of formulated cakes
The processed cakes were analyzed for their physical characteristics such as weight, height, specific volume ( Table 5). The height of the formulated cakes decreased with the increasing of JSP supplementation and was range from 4.04 to 4.70 cm. From the Table 5, it is seen that addition of different percentage of JSP resulted the increasing weight of cakes. The specific volume, the ratio of volume and weight is an important parameter for physical analysis of bakery products also decreased with the increasing of JSP amount as shown in Table 6. Similar results were obtained by Das (2017) in all of above cases where cakes were prepared from mango kernel flour. The processed cakes also were analyzed for their crust and crumb characteristics like color, consistency, flavor, texture etc and the obtained results are depicted in Table  6.
From the Table 6 and Figure 2, it is seen that the addition of JSP had an effect on the characteristics of crust and crumb of the composite cakes which lead to reveal that acceptability of JSP supplemented cakes could be decreased due to higher percentage of JSP supplementation.

Sensory evaluation of cakes
The color, flavor, texture, taste and overall acceptability of 4 samples of the formulated cakes were evaluated by taste testing panel. The mean scores for color, flavor, texture and overall acceptability of different samples were presented in Figure 3. A two way analysis of variance indicated that the color, flavor, texture, taste and overall acceptability of the different cakes were significantly different (P<0.05).
From the score sheet and LSD multiple comparison test, it was found that the JSP supplemented cakes obtained lower score than the control cake sample. Based on this sensory evaluation, it can be concluded that JSP addition to cakes could not get better choice to the consumer. But as all the scores of all samples were higher than 6, so it can be revealed that all cake samples were liked by the taste panelists.

Conclusion
Utilization of Jamun seed powder in different food products can help in effective utilization of wastage of Jamun seed as well as to get nutritionally better products. In this study, it was found that Jamun seed powder had higher energy content, fiber and mineral than wheat flour which is commonly used in bakery products. Analysis on replacement of wheat flour with Jamun seed powder in composite cake processing showed that composite cakes provide more energy than control one, also good physical characteristics and consumer acceptability up to 10% supplementation. Further research can be conducted to analyze the specific micronutrients, antioxidant activity, cost estimation and minimization etc.