Abstract
Management of agro-industrial waste is an important area of study for researchers with multifarious objectives. Conversion of such wastes into useful food products has emerged as a bountiful industry e.g. mango seed kernel. It contains appreciable quantities of edible oil thus holds various food applications due to presence of higher amount of oleic and stearic acid. In the present research, the lipid fraction from mango kernel were extracted and explored for their potential to replace (varying from 5 to 25%) normal shortenings in cereal baked products. In the first phase, lipid fraction was characterized for various physical and chemical traits. Later, the products were evaluated for their textural and color profile along with physical and chemical characteristics. Lastly, trained taste panel was hired to assess the suitability of product for commercialization. The results were quite conclusive that the lipid fraction melts at normal temperature (26.2°C) thus can be used to replace normal biscuits shortening. The results further indicated that addition of mango kernel lipid fraction influenced physical characters of cookies significantly, while chemical parameters remained insignificant. However, peroxide and thiobarbituric acid values decreased showing the improved oxidative stability and reduced free radical production. The sensory panelists were of the view that cookies containing 15 & 20% mango kernel lipid fraction are suitable for human consumption. In the nutshell, extraction of mango kernel lipid fraction and its utilization in baked products can results in saving millions of foreign exchange reserves for Pakistan thus contributing food security in edible oil sector.
Introduction
In the developing economies, the problem of food security is one of the burning issues. Although, Pakistan is regarded as agricultural economy but still there are some sectors where self sufficiency can't be claimed. Amongst, edible oil production is one example as country is spending ∼2.45 billions dollars on importing palm, sunflower, canola, and soybean oil to meet its domestic requirements (GOP, 2011-12). The problems of food security can be addressed using multilateral approaches. Since, a substantial segment of the population in Pakistan has been living below the poverty line. Their purchasing power for basic eatable commodities has been diminishing day by day. Therefore, the situation calls for the utilization of some alternative cheap sources which could be furnished into low-price and economical food grade edible oil. In this regard, agro-industrial waste products generated at farm or processing areas are of considerable importance as most of them hold bright prospects for utilization. These wastes constitute various nutrients (protein, dietary fiber, prebiotics, antioxidants, polyphenols etc.) and rheological agents (gelling agents, hydrocolloids, edible films & coatings, etc.). Numerous high valued products as nutraceuticals & functional ingredients, pharmaceuticals, cosmetics as well as various food grade colorants & flavors can also be obtained (Ajila et al., 2010).
Kernels, pomace and peels of some tropical fruits contain protein degrading enzymes as papain & bromelain from papaya & pineapple, respectively (FAO, 2005; Kammerer et al., 2005). Mango seed kernel is one such example that contains appreciable quantities of edible oil & proteins and holds potential for its inclusions in different food products. Moreover, mango-seed kernel contains some phytochemicals of interests that can be further utilized as natural antioxidants in food chains. At present, Pakistan is producing 1.8 million metric tons of mangoes costing ∼ 56 billion rupees (∼550 million US dollars). Mango-seed kernel is 20% of total fruit weight and therefore Pakistan is wasting around 3.6 million metric tons of produce. In Pakistan, very little efforts have been made to utilize mango seed kernel for the preparation of value added food products. The utilization of this huge waste material for the extraction of lipid fractions is of considerable concern to meet its domestic needs that will result in reduction of trade deficit and save million of dollars (Arogba et al., 1998). The potential of mango seed kernel is also valuable owing to higher contents of fiber and proteins. Various scientists have explored the mango kernel as a source of starch, proteins, antioxidant and other nutrients. The composition of mango kernel supports its use in composite flour technology (Arogba et al., 1998; Arogba, 2001). The concepts of value addition need to be introduced in food industries as there are huge productions of agro-industrial waste materials. Such dietary intervention may yield multifarious objectives ranging from waste-management to reducing the extent of food insecurity conditions in Pakistan.
Little efforts have been made to utilize mango seed kernel for the preparation of value added food products in Pakistan so far. Internationally price of mango kernel lipid fraction is 28 dollars for 4 ounce packet. Although, the mango-seed kernel contains around 10 - 12% oil contents (Hug et al., 1985) but no planned study has been documented so far focusing upon the utilization and management of mango waste for the production of edible oil in Pakistan. The current study aims to explore the possibilities to exploit mango waste (Kernel seed) for obtaining oil for its utilization in various forms in food. The extraction of edible oil from mango-seed kernel needs to be revolutionized as some older techniques like hydraulic and screw press are not suitable for this commodity. Therefore, solvent extraction system using hexane was used for the purpose. The extracted oil was evaluated for its physical and chemical quality along with assessing its suitability to replace normal biscuit shortenings. Initially, mango kernels were collected and analyzed for nutritional composition. Later, the lipid fraction was extracted and used to replace normal biscuits shortening and its suitability in cereal products was assessed. The results from this study will result in commercialization and stakeholders can utilize the present research for industrialization.
Materials and Methods
Present research was conducted in the Postgraduate Research Laboratory, Department of Food Science and Technology, Bahauddin Zakariya University, Multan. In the current investigation, mango kernel seeds of local origin were characterized for their lipid fraction and explored further for their potential to replace normal shortening in cereal baked products.
Materials Mango kernels of indigenous variety were obtained from the precincts of Multan. Raw materials for cookies preparation were procured from local market while reagents (analytical and HPLC grade) and standards were purchased from Sigma-Aldrich (Sigma-Aldrich Tokyo, Japan) and Merck (Merck KGaA, Darmstadt, Germany).
Characterization of mango kernel seed Mango kernel seeds were analyzed for various quality attributes including proximate analysis and mineral composition. The procedures followed are given below. For the purpose, mango kernel seed were washed and oven dried at 60°C for 1 hour. We ground the dried material further to fine powder and passed through sieves (425 µm & 500 µm) in order to remove coarser particles. The raw materials were analyzed for their proximate compositions i.e. moisture, proteins, fat, fiber, ash, and nitrogen free extract (NFE) contents.
(1) Proximate composition
The seed samples were analyzed for moisture, ash, crude protein, crude fat and crude fiber according to their Method No. 44 - 01, Method No. 08 - 01, Method 46 - 13 Method 30 - 10, Method 32 - 10, respectively, as described in AACC (2000). The nitrogen free extract (NFE) was calculated according to the following expression: NFE% = 100 - (moisture% + ash% + crude protein% + crude fat% + crude fiber%)
(2) Mineral composition
For mineral determination, wet digestion of the all samples was carried out according to the method of Jones et al. (1990). For the purpose 0.5 g of sample was taken, and was digested with 10 mL HNO3 and 5 mL HClO4 at higher temperature till volume was reduced to 1 - 2 mL. The digested samples were transferred to 100 mL volumetric flask and volume was made up to the mark using distilled water and then filtered (Whatman filter Paper: pore size 45 µm). The minerals Ca, Mg, Zn, S, P and Fe were determined using Atomic Absorption Spectrophotometer (Varian AA240, Germany) while Na and K are estimated through Flame Photometer (Sherwood 410, UK).
Extraction and characterization of mango kernel lipid fraction The oil from the mango kernel seed was extracted through solvent extraction technique as described in AOCS (1998) using hexane as solvent (Eyela, Japan). Physical and chemical characteristics using their respective methodologies were determined. Physical characteristics include color (Method Cc 10a - 25: AOCS, 1998), refractive index (Method Cc 10a - 25: AOCS, 1998), flavor (Method Cc 10a - 25: AOCS, 1998), specific gravity (Method Cc 10a - 25: AOCS, 1998), specific extinction (Method Cc 10a - 25: AOCS, 1998) and smoke & flash point (Method Cc 10a - 25: AOCS, 1998). Chemical parameters include free fatty acids (Method Ca 5a - 40: AOCS, 1998), peroxide value (Method Cd 8 - 53: AOCS, 1998), Thiobarbituric acid value (Method Cd 19 - 90: AOCS, 1998), Acid value (Method Cc 10a - 25: AOCS, 1998), iodine value (Method Cd 1 - 25: AOCS, 1998) and saponification value (Method Cd 3 - 25: AOCS, 1998).
Product development Cookies were prepared with some modification in the method given in AACC (2000) by gradually replacing normal shortening (Table 1) with mango kernel lipid fraction (MKLF) and along with normal biscuits shortening (NBS) as control to determine its Suitability in the end product. The normal shortenings were replaced gradually from 5 to 25% i.e. T0 (250.0 NBS), T1 (12.5 g MKLF and 237.5 g NBS), T1 (25.0 g MKLF and 225.0 g NBS), T3 (37.5 g MKLF and 212.5 g NBS), T4 (50.0 g MKLF and 200.0 g NBS) and T5 (62.5 g MKLF and 187.5 g NBS), respectively. Cookies were prepared using the standard protocols mentioned in AACC (2000). Briefly, grinded sugar and shortenings were creamed together and egg white and egg yolk (as per requirements) was added and beaten till homogenous mass. Later, the dry ingredients like wheat flour (50%), and baking powder (0.5%) were added and mixed gently to homogeneity.
Table 1.
Proximate and mineral composition of mango kernel flour
| Proximate composition (g/100 gm) |
| Moisture |
8.65 ± 0.41 |
| Protein |
8.71 ± 0.17 |
| Fat |
12.50 ± 0.31 |
| Fiber |
3.27 ± 0.11 |
| Ash |
2.23 ± 0.09 |
| Nitrogen free extract (NFE) |
64.64 ± 0.39 |
| Minerals (mg/100 gm) |
| Phosphorus |
137.03 ± 3.41 |
| Calcium |
115.30 ± 7.51 |
| Magnesium |
98.26 ± 4.31 |
| Potassium |
23.03 ± 1.40 |
| Sodium |
19.25 ± 0.84 |
| Manganese |
11.52 ± 0.77 |
| Iron |
7.15 ± 0.40 |
| Copper |
1.17 ± 0.07 |
| Zinc |
1.05 ± 0.09 |
Analysis of Cookies
(1) Physical analysis
The width, thickness and spread factor for cookies were estimated according to the method described in AACC (2000). For the purpose, width and length of cookies was measured by placing six biscuits horizontally and vertically (edge to edge) and rotated at 90° angles for duplicate reading. The spread factor was calculated according to the formula (SF = W/T × CF × 10), where CF = correction factor, W = width/diameter of cookies, and T = thickness of cookies.
(2) Color tonality and textural analysis
The color of cookies prepared with different levels of defatted mango kernel flour supplementation was determined using CIE-Lab Color Meter (CIELAB SPACE, Color Tech-PCM, USA). 5 gram of sample was taken and color values as “L*” (lightness), “a*” (−a greenness; +a redness), and “b*” (−b blueness; +b yellowness) were recorded. The data thus obtained was used to calculate chroma and hue angle (Gouveia et al., 2005). The measurements were recorded under constant lighting condition using a white tile control (L* 97.46, a* 0.02, b* 1.72). The texture analysis of cookies prepared with added levels of defatted mango kernel flour was carried out. The parameters like fracture-ability and hardness were measured using the protocols described by Mamat and Hill (2012).
(3) Sensory Evaluation
The cookies were evaluated by a panel of judges from the teachers and postgraduate students of Department of Food Science & Technology for taste, color, flavor, texture and overall acceptability according to the procedure described by Meilgaard et al., (2007).
Statistical Analysis The data obtained from each parameter was subjected to statistical analysis to determine the level of significance according to the methods as described by Steel et al. (1997). During the sensory evaluation, cookies with different mango kernel lipid fraction were placed in transparent cups, labeled with random codes. Cold mineral water and crackers were supplied to panelists for rinsing their mouths between the samples. In each session, panelists were seated in separate booths equipped with white fluorescent lighting in an isolated room.
Results
The proximate and mineral composition is important in determining the nutritional quality and shelf life of any product. Amongst, moisture content is an important determinant to assess the quality and shelf life of the food products. In the present study, the results regarding wheat flour and mango kernel flour (Table 1) indicated that moisture and proteins contents mango kernel were recorded to be 8.65 ± 0.41 and 8.71 ± 0.17 g/100 gm, respectively. However, fat contents were quite higher in mango kernel (12.50 ± 0.31 g/100 gm) along with fiber and ash contents i.e. 3.27 ± 0.11 g/100 gm, and 2.23 ± 0.09 g/100 gm respectively. The determination of mineral contents revealed that mango kernel contains phosphorus, calcium, magnesium, potassium, sodium, manganese, iron, copper, and zinc in appreciable amounts i.e. 137.03 ± 3.40, 115.30 ± 7.51, 98.26 ± 4.31, 23.03 ± 1.40, 19.25 ± 0.84, 11.52 ± 0.77, 7.15 ± 0.40, 1.17 ± 0.07, 1.05 ± 0.09 mg/100 gm respectively.
Mango kernel lipid fraction was extracted (AOCC, 1998) using hexane as solvent. The lipid fraction was refined using degumming & neutralization techniques and tested for various physical and chemical characteristics (Table 2). The melting point of mango kernel lipid fraction was recorded to be 26.2 °C. Means values for remaining physical parameters of fixed oil including specific gravity, refractive index, K232 and K270 values were 0.961 ± 0.002, 1.452 ± 0.021, 0.568 ± 0.005 and 0.260 ± 0.002, respectively. Likewise, means for chemical parameters like free fatty acid, POV, TBA, iodine & acid value, saponification value and unsaponifiable materials were 4.43 ± 0.721%, 6.72 ± 0.929 meq/kg, 0.69 ± 0.008 mg melonaldehyde/kg-oil, 77.31 ± 11, 2.130 ± 0.252 mg KOH/g, 188.13 ± 35.327 and 1.71 ± 0.164%, respectively. The values for free fatty acids were reduced to 0.05% using 0.1 N NaOH solution. In unrefined lipid fraction, the free fatty acids were in higher amounts (14.26%). The results regarding color tonality that was measured using CieLab color meter are also presented in the Table 2. The values for lightness (L*), greenish/yellowish (a*), bluish/reddish (b*), chroma and hue angle were found to be 30.08 ± 0.62, 7.01 ± 0.79, 31.22 ± 0.67, 36.29 ± 1.03 and 16.20 ± 1.01, respectively. The results indicated that oil was having slight dark yellowish tonality with glimpses of reddish color tonality.
Table 2.
Physical and chemicals parameters of mango kernel lipid fraction
| Physical parameters |
| Melting point |
26.20°C |
| CieLab color values |
| L* |
30.08 ± 0.62 |
| a* |
7.01 ± 0.79 |
| b* |
31.22 ± 0.67 |
| Chroma |
36.29 ± 1.03 |
| Hue angle |
16.20 ± 1.01 |
| Specific Gravity (g/cm3) |
0.96 ± 0.01 |
| Refractive Index |
1.45 ± 0.02 |
| K232 |
0.57 ± 0.01 |
| K270 |
0.26 ± 0.01 |
| Chemical parameters |
| Free Fatty Acid (%) |
4.43 ± 0.72 |
| POV (meq/kg) |
6.72 ± 0.93 |
| TBA value (mg malonaldehyde/kg-oil) |
0.69 ± 0.01 |
| Iodine Value (g/100 g) |
77.31 ± 11.77 |
| Acid Value (mg KOH/g) |
2.13 ± 0.25 |
| Saponification Value |
188.13 ± 35.33 |
| Unsaponifiable material (%) |
1.71 ± 0.16 |
In the product development phase, cookies were prepared with varying levels of mango kernel lipid fraction. The results pertaining to physical parameters reflected the significant influence of mango kernel lipid fraction on diameter, thickness and spread factor (Table 3). Addition of mango kernel lipid fraction increased the diameter significantly from 50.94 ± 0.48 to 54.01 ± 0.24 mm. Maximum thickness of 9.88 ± 0.01 mm) was observed in T4 (20% mango kernel lipid fraction), whilst T1 (5% Mango kernel lipid fraction) exhibited minimum thickness of 9.82 ± 0.01 mm. The highest spread factor (54.97 ± 0.18) was observed in T5 (25% mango kernel lipid fraction) as compared to the lowest (51.60 ± 0.36) in cookies prepared from 100% normal biscuit shortening.
Table 3.
Effect of mango kernel lipid fraction on physical parameters of cookies
| Treatments |
Diameter |
Thickness |
Spread factor |
| T0 |
50.94 ± 0.48c |
9.87 ± 0.03a |
51.60 ± 0.36c |
| T1 |
52.02 ± 0.05bc |
9.82 ± 0.01b |
52.95 ± 0.04bc |
| T2 |
52.13 ± 0.12bc |
9.86 ± 0.02a |
52.77 ± 0.07bc |
| T3 |
52.78 ± 0.07ab |
9.83 ± 0.01b |
53.57 ± 0.10ab |
| T4 |
53.13 ± 0.11ab |
9.88 ± 0.01a |
53.87 ± 0.05ab |
| T5 |
54.01 ± 0.24a |
9.85 ± 0.01ab |
54.97 ± 0.18a |
| F ratio |
5.126** |
4.921** |
5.963** |
| Effect of storage |
| S1 |
52.68 ± 1.03 |
9.86 ± 0.02 |
53.41 ± 1.11 |
| S2 |
52.50 ± 0.99 |
9.86 ± 0.03 |
53.27 ± 1.09 |
| S3 |
52.33 ± 1.16 |
9.84 ± 0.02 |
53.18 ± 1.22 |
| F ratio |
0.219ns |
2.858ns |
0.119ns |
SS*: Sum of squares indicating the level of significance
T0: Control (100% normal shortening), T1: 5.0% mango kernel lipid fraction and 95% normal shortening, T2: 10% mango kernel lipid fraction and 90% normal shortening, T3: 15% mango kernel lipid fraction and 85% normal shortening, T4: 20% mango kernel lipid fraction and 80% normal shortening, T5: 25% mango kernel lipid fraction and 75% normal shortening
The results for color values indicated that indices of color tonality were significantly altered as a function of treatments (Table 4). L* value of cookies decreased from 70.80 ± 1.56 (control) to 65.52 ± 1.54 (T5 25% mango kernel lipid fraction) as a function of mango kernel lipid fraction. The values for a* representing reddish tonality were in range of 1.67 ± 0.03 to 5.70 ± 0.11. The values for b* showed the same trend as that of L* and a*. Increasing the amount of mango kernel lipid fraction affected the said trait significantly and values were in the range of 18.97 ± 0.50 to 21.49 ± 0.16. Chroma (color density) and color shade (hue angle) decreased as a function of mango kernel lipid fraction. The textural analysis of cookies indicated that the maximum hardness was recorded in 10% mango kernel lipid fraction biscuits (2943.85 ± 44.55G) as compared to the minimum for in T0 (100% normal shortening) i.e. 1594.38 ± 44.44G (Table 4). Likewise, the fracturability of cookies prepared with mango kernel lipid fraction varied significantly but without some commercial values. The fracturability was in the range of 76.28 ± 1.49 and 72.58 ± 1.99 Mm.
Table 4.
Effect of mango kernel lipid fraction on color tonality and textural profile of the of cookies
| Treatments |
L* |
a* |
b* |
Chroma |
Hue |
Hardness |
Fracturability |
| T0 |
70.80 ± 1.06a |
5.70 ± 0.11a |
21.49 ± 0.37a |
22.23 ± 0.50a |
75.14 ± 1.17d |
1594.38 ± 44.44e |
74.31 ± 1.36b |
| T1 |
69.06 ± 1.79b |
1.83 ± 0.03c |
18.97 ± 0.40d |
19.06 ± 0.29a |
84.49 ± 0.96a |
2381.69 ± 22.72c |
75.58 ± 0.34a |
| T2 |
68.02 ± 2.06bc |
1.67 ± 0.03c |
19.22 ± 0.54cd |
19.29 ± 0.39a |
85.03 ± 1.89a |
2943.84 ± 44.55a |
76.28 ± 1.45a |
| T3 |
67.11 ± 1.01cd |
3.02 ± 0.05b |
20.94 ± 0.61ab |
21.16 ± 0.27a |
81.79 ± 1.59b |
2085.42 ± 34.33d |
73.55 ± 2.68c |
| T4 |
66.41 ± 1.04de |
3.08 ± 0.05b |
20.34 ± 0.51b |
20.57 ± 0.52a |
81.39 ± 1.60b |
2456.89 ± 23.44c |
73.75 ± 1.28c |
| T5 |
65.52 ± 1.54e |
3.55 ± 0.02b |
19.87 ± 0.61bc |
20.19 ± 0.38a |
79.87 ± 0.56c |
2687.31 ± 17.62b |
72.58 ± 1.99d |
| F ratio |
54.721** |
31.850** |
14.372** |
21.104ns |
192.896** |
3358258.966** |
28.157** |
SS*: Sum of squares indicating the level of significance
T0: Control (100% normal shortening), T1: 5.0% mango kernel lipid fraction and 95% normal shortening, T2: 10% mango kernel lipid fraction and 90% normal shortening, T3: 15% mango kernel lipid fraction and 85% normal shortening, T4: 20% mango kernel lipid fraction and 80% normal shortening, T5: 25% mango kernel lipid fraction and 75% normal shortening
The chemical composition of cookies was evaluated that include the determination of moisture proteins, fats, ash, fiber, and nitrogen free extract. The results indicated that moisture contents of the different mango kernel lipid fraction supplemented cookies ranged from 3.26 ± 0.06 to 4.98 ± 0.10 among different treatments (Table 5). Likewise, protein content of different treatments ranged from 4.87 ± 0.01 to 5.84 ± 0.09%. Similar to proteins, fats contents of cookies were recorded to be in range of 27.33 ± 0.35 to 28.80 ± 0.34%. The results revealed that the highest crude fiber was found to be (0.41 ± 0.02%) in the T5 followed by T4 (0.41 ± 0.02%). Ash contents of 0.20 ± 0.04%, 0.20 ± 0.03%, and 0.19 ± 0.04% were recorded in cookies prepared with 10, 20, and 25% mango kernel lipid fraction, respectively. The NFE content indicated that the highest value of 63.79 ± 0.32% was observed in cookies prepared with 100% normal shortening as compared to the lowest (60.83 ± 0.25%) T5 (25%: mango kernel lipid fraction).
Table 5.
Effect of mango kernel lipid fraction proximate composition of cookies
| Treatments |
Moisture |
Crude Protein |
Crude Fat |
Ash |
Fiber |
NFE |
| T0 |
3.50 ± 0.10d |
4.90 ± 0.04c |
27.33 ± 0.35 |
0.36 ± 0.02b |
0.12 ± 0.03c |
63.79 ± 0.32a |
| T1 |
4.02 ± 0.17bc |
5.16 ± 0.03b |
28.34 ± 0.61 |
0.41 ± 0.01a |
0.13 ± 0.02bc |
61.94 ± 0.47b |
| T2 |
3.90 ± 0.41bcd |
5.26 ± 0.10b |
28.30 ± 0.40 |
0.39 ± 0.02a |
0.20 ± 0.04a |
61.95 ± 0.20bc |
| T3 |
3.64 ± 0.32cd |
5.53 ± 0.15a |
27.59 ± 0.07 |
0.39 ± 0.02a |
0.18 ± 0.03ab |
62.67 ± 0.15bc |
| T4 |
4.90 ± 0.08a |
5.59 ± 0.19a |
27.62 ± 0.07 |
0.41 ± 0.02a |
0.20 ± 0.03a |
61.29 ± 0.26cd |
| T5 |
4.11 ± 0.35b |
5.66 ± 0.16a |
28.80 ± 0.34 |
0.41 ± 0.02a |
0.19 ± 0.04a |
60.83 ± 0.25d |
| F ratio |
10.647** |
0.444ns |
2.849ns |
1.970ns |
1.564ns |
9.310** |
| Effect of storage |
| S1 |
3.74 ± 0.57b |
5.47 ± 0.37 |
28.35 ± 0.72 |
0.40 ± 0.02a |
0.20 ± 0.04 |
61.84 ± 1.07 |
| S2 |
4.11 ± 0.46a |
5.32 ± 0.28 |
27.85 ± 0.53 |
0.40 ± 0.02a |
0.18 ± 0.04 |
62.07 ± 1.08 |
| S3 |
4.17 ± 0.48a |
5.26 ± 0.25 |
27.79 ± 0.50 |
0.38 ± 0.02b |
0.14 ± 0.03 |
62.32 ± 1.03 |
| F ratio |
4.920* |
0.007ns |
1.657ns |
1.934ns |
5.460ns |
0.971ns |
*NFE stands for nitrogen free extract: ** SS: Sum of squares indicating the level of significance
T0: Control (100% normal shortening), T1: 5.0% mango kernel lipid fraction and 95% normal shortening, T2: 10% mango kernel lipid fraction and 90% normal shortening, T3: 15% mango kernel lipid fraction and 85% normal shortening, T4: 20% mango kernel lipid fraction and 80% normal shortening, T5: 25% mango kernel lipid fraction and 75% normal shortening
Sensory evaluation is an important standard for quality assessment of new product and is usually performed towards the end of the product development and to meet the consumer requirements. In general, cookies prepared with varying levels of mango kernel lipid fraction showed significant variations in all traits. Overall means for color (Table 6) revealed that the maximum score of 8.10 ± 0.28 was assigned to T5 (25% mango kernel lipid fraction) as compared to minimum scores for T0 (7.01 ± 0.13). Increasing mango kernel lipid fraction improved the taste scores significantly; maximum 7.59 ± 0.32 were assigned to T4 (20% mango kernel lipid fraction), whilst minimum score (7.15 ± 0.13) was assigned to T0 (control). There exist significant variations in texture and flavor and the maximum scores of 7.50 ± 0.19 and 7.53 ± 0.31 were assigned to T4 (20% mango kernel lipid fraction) for texture and flavor respectively, for the said traits as compared to least rating for cookies prepared with 100% normal shortening. Moreover, the maximum scores for crispness i.e. 7.29 ± 0.38 was given to T1 (5% mango kernel lipid fraction), whereas, the minimum scores i.e. 7.07 ± 0.18 were assigned to T5 (25% mango kernel lipid fraction). Overall acceptability for treatments indicated that maximum score was assigned to T3 (15% mango kernel lipid fraction) and T4 (20% mango kernel lipid fraction) i.e. 7.40 ± 0.20 and 7.40 ± 0.10, respectively (Table 6). However, rest of the treatments containing mango kernel lipid fractions were rated closely.
Table 6.
Effect of mango kernel lipid fraction on sensory evaluation and antioxidant stability
| Treatments |
Color |
Flavor |
Texture |
Taste |
TBA |
Peroxide |
| T0 |
7.01 ± 0.13e |
6.73 ± 0.23c |
7.05 ± 0.08d |
7.15 ± 0.13e |
38.854 ± 8.76a |
0.321 ± 0.15a |
| T1 |
7.25 ± 0.18d |
7.12 ± 0.29b |
7.13 ± 0.11cd |
7.18 ± 0.16de |
37.169 ± 6.88b |
0.305 ± 0.14b |
| T2 |
7.48 ± 0.17c |
7.19 ± 0.13b |
7.17 ± 0.16c |
7.28 ± 0.27cd |
34.407 ± 4.97c |
0.271 ± 0.11c |
| T3 |
7.81 ± 0.16b |
7.24 ± 0.17b |
7.33 ± 0.34b |
7.38 ± 0.27bc |
33.402 ± 3.45cd |
0.240 ± 0.08d |
| T4 |
8.06 ± 0.29a |
7.53 ± 0.31a |
7.50 ± 0.19a |
7.59 ± 0.32a |
32.070 ± 2.06d |
0.198 ± 0.05e |
| T5 |
8.10 ± 0.28a |
7.21 ± 0.13b |
7.32 ± 0.20b |
7.49 ± 0.17ab |
30.600 ± 0.49e |
0.172 ± 0.01f |
| F ratio |
95.169 ** |
41.403** |
21.889 ** |
16.913** |
40.284** |
259.089** |
| Effect of storage |
| S1 |
7.81 ± 0.50a |
7.33 ± 0.27a |
7.39 ± 0.23a |
7.55 ± 0.26a |
29.974 ± 0.40c |
0.159 ± 0.01c |
| S2 |
7.61 ± 0.48b |
7.24 ± 0.26b |
7.31 ± 0.18b |
7.34 ± 0.20b |
34.503 ± 3.63b |
0.261 ± 0.07b |
| S3 |
7.43 ± 0.38c |
6.93 ± 0.27c |
7.05 ± 0.13c |
7.15 ± 0.14c |
38.774 ± 5.94a |
0.334 ± 0.10a |
| F ratio |
34.035 ** |
54.320** |
49.699 ** |
44.003** |
40.284** |
1153.834** |
SS*: Sum of squares indicating the level of significance
T0: Control (100% normal shortening), T1: 5.0% mango kernel lipid fraction and 95% normal shortening, T2: 10% mango kernel lipid fraction and 90% normal shortening, T3: 15% mango kernel lipid fraction and 85% normal shortening, T4: 20% mango kernel lipid fraction and 80% normal shortening, T5: 25% mango kernel lipid fraction and 75% normal shortening
Discussion
Mango kernel is agricultural waste/byproduct and little attention has been paid to explore its potential as edible oil source.
In Pakistan, very few efforts have been made to utilize mango seed kernel for the preparation of value added food products. In the first phase of the present project, the nutritional composition of mango kernel and lipid fraction was evaluated. Mango kernel contains ∼12.0% fats that can be extracted using hexane as solvent. Previously, Van et al., (1981) and Lakshminarayana et al. (1983) examined different mango varieties for their oil quality. Their results revealed that fat contents of mango kernel vary from 2.1 to 10.3%. Their results with reference to physical and chemical parameters of mango kernel lipid fraction can be used as reference material. However, the melting behavior of lipid fraction extracted in the present study was different from the values reported in literature and it could be possibly due to presence of higher concentrations of oleic acids as compared to stearic acid. Most of the scientific research interventions conducted over the globe were of the view that mango kernel contains ∼65 to 85% stearic and oleic acid. More recently, Muchiri et al., (2012) determined that the melting point of 25 - 33°C for mango kernel oil, iodine value of 51.06 - 56.79, acid value 4.49 - 7.4 free fatty acid 2.26 - 3.76, saponification number of 188.3 - 195.9, unsaponifiable matter of 2.26 - 2.74% peroxide value 0.40 - 0.75, refractive index 1.45 and specific gravity of 0.90 g/cm3.
In the later stages, the normal biscuit shortenings were replaced with mango kernel lipid fraction and cookies were prepared and evaluated for various traits. The results are conclusive that mango kernel lipid fraction enhanced the diameter of the cookies, while rest of the physical traits varied non-significantly. Generally, formulations containing oil had relatively greater spread as compared to shortening probably because of poor entrapment of air (Jacob and Leelavathi, 2007; Caponio et al., 2008). Moreover, spread potential of biscuits depends on flour particle size, water-ingredients (water, starch slurry, glucose syrups), and emulsifiers (Gaines and Donelson, 1985). Present findings are in conformation with the results of Pareyt et al., (2009) who reported similar effects of fat on structure and texture characteristics of sugar-snap cookies. Although, results contradict with the findings of the other scientist who utilized corn, sunflower, black cumin oil in cookies formulations (Hussain et al., 2006; Sultan et al., 2012). The reasons for this trend could possibly be due to nature of mango kernel lipid fraction and its melting behavior. It has melting point in the range of 26.2°C that is slight lower than the normal shortening thus the results were similar to that of control cookies in thickness and spread factor (Caponio et al., 2008). Color changes with the addition of mango kernel lipid fraction were found to be significant and could be due to presence of coloring components present in mango kernel lipid fraction. Generally, the variations in color tonality of cookies could be due to many reasons including ingredients (sugar and proteins), and indeed color of final product is always dependent upon the raw materials used that ultimately affect color tone of the products (Cheikh-Rouhou et al., 2007; Gallagher et al., 2003; Gouveia et al., 2007).
The textural profile of cookies containing mango kernel lipid faction was carried out for the first time as per author's best knowledge. However, there are some other scientists over the globe who studied the textural features of the cookies prepared with different formulations (Arogba, 2001). In this regard, results of Mamat and Hill (2012) can be correlated who studied the effect of fat types on the structural and textural properties of dough and semi-sweet biscuit (O'Brien et al., 2003; Yadav et al., 2012).
Chemical parameters were not affected as a function of progressive increase in mango kernel lipid fraction and values for moisture, protein, fats, fiber, ash and NFE remained in the ranges recorded in the literature (Mehmood et al., 2008; Sultan et al., 2012). However, peroxide and TBA values were significantly reduced with additional increments of mango kernel lipid fraction. Findings of present study could be correlated with the research investigations of Sultan et al. (2012) and Paradiso et al., (2008); they observed improved oxidative stability of the respective products with addition of polyphenol-rich materials. However, aluminum foil packaging in the present research protected cookies from deleterious effect of surroundings (Baik et al., 2000; Mehmood et al., 2008). Color is very important in judging the properly baked cookies that not only reflects the suitable raw material used for the preparation but also provides information about the formulation and quality of the product (Hussain et al., 2006). Color of cookies is dependent upon many factors i.e. selection of ingredients, caramelization, Millard reaction, etc. In the present research, mango kernel lipid fraction was added that is having little reddish tonality. The effect was pronounced and rating for color was increased. The overall acceptability determined by the trained taste panel identified the significant differences among the cookies prepared from various levels of mango kernel lipid fraction. However, it is evident from the results that cookies with all formulations were quite acceptable. In many investigations, variations in sensory scores as a function of supplementation of oil & antioxidants and storage are supporting the present findings (Arshad et al., 2007; Sultan et al., 2012). Usually, the level of shortening used in the preparation of cookies was kept constant and addition of mango kernel oil was coupled with similar replacement of normal shortenings. However, trained taste panel who was already informed with the justifications of the research rated cookies prepared with 100% normal shortening with the least score i.e. 7.00 ± 0.172.
The results of Agroba (1999) were well in accordance with the present study. However, the results from the present study can't be compared with other studies as according to best of author's knowledge, it is first kind of study in its own to incorporate mango kernel lipid fraction in cookies formulations. Although, the some other scientists has already attempted to include oil with some functional properties e.g. rice bran oil (Sharif et al., 2005), wheat germ oil (Arshad et al., 2007), black cumin oil (Sultan et al., 2012) in cookies formulation but their results are not in accordance with the present research due to different nature of material used. Results of present investigation are in corroboration with that of Sharif et al., (2005) and Arshad et al., (2007). In the nutshell, the cookies prepared with 15 and 20% were more liked by the sensory panel thus recommending its use in the bakery products. Cookies prepared with 20% replacement of normal shortening with mango kernel lipid fraction were rated better considering the hedonic response. However, it is evident from the results that cookies with all formulations were quite acceptable.
Conclusion
The extraction of mango kernel lipid fraction is valuable for the Pakistan's economy as it can be utilized to replace expensive normal biscuits shortenings. The results were conclusive that mango kernel lipid-fraction can be used to replace 15% normal biscuits shortening and cookies were acceptable to the sensory panel. In the future, bakery shortenings can be developed using mango kernel lipid fraction. Moreover, attempts should also be made to utilize defatted mango kernel flour in composite flour blends along with optimization the processes for the extraction of principal ingredients e.g. starch and proteins for value addition.
Acknowledgement The authors are thankful to Post-Harvest Research Institute, Faisalabad for providing facilities to carry out color analysis. The authors are also thankful to National Institute of Food Science and Technology, University of Agriculture, Faisalabad for providing instrument facilities to carry out textural analysis.
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