South Western Journal of Vol.2 , No.1, 2011 Horticulture, Biology and Environment pp.1- 13 P-Issn: 2067- 9874, E-Issn: 2068-7958 PHYSICO-CHEMICAL PROPERTIES OF APRICOT (Prunus armeniaca L.) KERNELS İbrahim GEZER1, Haydar HACISEFEROĞULLARI2, Mehmet Musa ÖZCAN3*, Derya ARSLAN3, Bayram Murat ASMA4, Ahmet ÜNVER3 1. Inonu University, Technician Training Center, Programme of Agricultural Machinery, 44100 Malatya, Turkey 2. Department of Agricultural Machinery, Faculty of Agriculture, University of Selçuk, 42031 Konya, Turkey 3. Department of Food Engineering, Faculty of Agriculture, University of Selçuk, 42031 Konya, Turkey 4. Department of Biology, Faculty of Science-Education, Inonu University, 44100 Malatya, Turkey *Corresponding address: M.M. ÖZCAN, E-mail: [email protected] Abstract. The nutrients and physical properties of the five samples of ap- ricot (Prunus armeniaca L.) kernels were determined in this study. Physical properties such as mass, length, width, thickness, geometric av- erage diameter, sphericity, surface values, volume, bulk density, kernel density, porosity, terminal velocity, projected area and rupture strength, static coefficient of friction were determined at 2.98% (Çataloğlu), 2.18% (Hacıhaliloğlu), 2.46% (Hasanbey), 2.47% (Kabaaşı) and 3.25 % (Soğanoğlu) moisture content. Crude oil, dry matter, crude protein and crude fibre contents of apricot kernels were established between 28.26% to 42.48%, 96.75% to 97.82%,15.7% to 18.3% and 5.3% to 7.1%, 2.91 to 3.83%, respectively. Mineral content of apricot kernels collected from Malatya- Turkey were determined by an Inductively Cou- pled Plasma Atomic Emission Spectrometer (ASP-AES). All kernels con- tained high amounts Ca, K, Na and P. As a result, apricot kernel may be useful for the evaluation of nutritional information and oil source. Key words: apricot, kernel, oil, composition, physical properties INTRODUCTION Apricot (Prunus armeniaca L.) is classified under the Prunus species of Rosaceae family of the Rosales group. Apricot has an important place in human nutrition, and can be used as fresh, dried or processed fruit. Ap- ricot kernels are used in the production of oils, benzaldehyde, cosmetics, © South west J Hortic Biol Environ Craiova, Romania http://anucraiova.3x.ro/swjhbe/index.html 2011 2 Gezer, I. et al. active carbon, and aroma perfume (Yıldız 1994). Their kernels make an important contribution to the diet in many countries. They are used as vegetable (fresh fruit) and are a good source of protein, lipid, and fatty ac- ids for human nutrition. The fatty acid composition of the endogenous fats plays an important role in determining shelf life, nutrition, and flavour of food products (Gao & Mazza 1995). Kernels of some apricots are sweet, and can be eaten as roasted and salted titbit. The most important apricot cultivars grown and used as sources for dried fruit are Çataloğlu, Çöloğlu, Hacıhaliloğlu, Kabaaşı and Hasanbey. In addition to these, Ordubat, Şam, Şalak, Şekerpare, Tokaloğlu and Teberze cultivars are used as table fruits varieties. Abd-Aal et al. (1985) and Khalil & Rahma (1986) deter- mined that there is an important proportion of oil (50%) and other com- pounds such as benzaldehyde, surface active agents and proteins in Egyptian apricot kernels (Joshi et al. 1993). Beyer & Melton (1990) have studied the composition of New Zealand apricot kernels. Kernels of apricot, peach, plum and almond belong to this family are produced as byproducts in tonnages from food canning industry. The kernels are considered as non-traditional potential resources for oils (Banerjee & Subrahmanyam 1985; Hassanein 1999). The cosmetic uses of the oil obtained from other Prunus kernels have already been determined and characterised particularly for apricot, peach, plum and cherry oils (Femenia et al. 1995, Johansson et al. 1997). Food companies produce large amounts of preserved fruits at the expense of large amounts of waste. Several fruit seeds, such as cherry, apricot, citrus and apple can be used as sources of oils. The seed oils are already used for several purposes: blending with highly saturated edible oils to provide new oils with modified nutritional values, as ingredients in paint and varnish formulations, surface coatings and oleo-chemicals, and as oils for cosmetic purposes (Hauhout-Helmy 1990). Currently, large amounts of fruit seeds are discarded yearly at processing plants. This not only wastes a potentially valuable resource but also aggravates an al- ready serious disposal problem. To be economically viable, however, both oil and meal from these fruit seeds must be utulized (Kamel & Kakuda 1992). To active the most economical and efficient utilization of these seeds, more information on the varieties, properties, and compo- sition is required. Two main varieties of apricot kernels can be easily dif- ferentiated: sweet and bitter kernels (Femenia et al. 1995). Some uses of apricot kernel oil in cosmetics and for medical purposes were reported by Hallabo et al. (1975). The possibility of mixing crude edible oil with crude fruit seed oils, such as apricot kernel oil, and then processing the oil mixture by the conventional methods of refining and South west J Hortic Biol Environ (2011) Physico-chemical properties of apricot kernels 3 bleaching was analysed by Hauhout-Helmy (1990). Previous studies on some Rosaceae kernel oils had been reported by some authors (Hassanein 1999, Farine et al. 1986). Kernel oils of peach and apricot have been used as adulteratns or substitutes for some expen- sive oils particularly, almond oil (Egan et al. 1981). The aim of this study was to determine the chemical and the physical properties of five apricot kernel cultivars (Soğanoğlu, Hacıhaliloğlu, Çata- loğlu, Kabaaşı and Hasanbey) widely grown in Turkey. MATERIAL AND METHODS Materials Five apricot cultivar kernels were obtained by hand processing from apricots growing in Malatya location of Turkey in August. Kernels were kept in glass jars until analyses at refrigerator. In all stages of trials, dry and mature kernels have been used. Methods Abreviations L - length of apricot kernel (mm) Pk - kernel density (kg/m3) M - mass of apricot kernel (g) I - thickness of kemel(mm) ifi moisture content. (%) d.b. V - volume of apricot kernel (mm) c - E - porosity of apricot kernel (%) Vt - terminal velocity (m/s) P - projected area (cm') W - width of apricot kernel (mm) a pb - bulk density (kg/m3) 0 - sphericity of apricot kernel Physical properties: All physical properties of kernels were determined using 20 repetitions at the natural moisture content of Soğanoğlu 3.25%, Hacıhaliloğlu 2.18%, Çataloğlu 2.98%, Kabaaşı 2.47% and Hasanbey 2.46% m.c.d.b. To determine the size of the kernels, ten groups of samples consisting of 100 kernels have been selected randomly. Ten kernels have been taken from each group and their linear dimensions - length (L,) width (W) and thickness (T) and projected areas have been measured. Linear dimensions were measured by a micrometer to an accuracy of 0.01mm. Projected area (P ) of kernels was determined by using a digital camera (Ko- a dak DC 240) and Sigma Scan Pro 5 program (Trooien & Heermann 1992). The Mass of kernels (M) were measured by an electronic balance to an accuracy of 0.001g. The bulk density (p^ was determined with a hectoliter tester which was cali- brated in kg per hectoliter (Deshpande et al. 1993). The apricot kernels were dropped down into a bucket from a height of approximately 15 cm.The ex- cess kernels were remored by sweeping the surface of the bucket. The kernels were not compressed in any way. South west J Hortic Biol Environ (2011) 4 Gezer, I. et al. The kernels volume (V) and its kernels density (pk), as a function of mois- ture content, were determined by using the liquid displacement method. Toluene (C H ) was used instead of water because it is absorbed by grains to a lesser ex- 7 8 tent. Also, its surface tension is low, so that it fills even shallow dips in a kernel and its dissolution power is low (Singh & Goswami 1996). The porosity (ε) was determined by the following equation: (1) e =l-pt/Pk In which p and pk are the bulk density and the kernel density, respectively b (Thompson & Isaacs 1967). The rupture strength values of apricot kernels were measured by forces ap- plied through three axis (length, width and thickness). The rupture strength of kernels, were determined with Test Instrument of Biological Materials (Figure 1) using the procedure described by Aydın and Öğüt (1991). The device, has three main components which are stable up and motion bottom of platform, a driving unit (AC electric motor and electronic variator) and the data acquisition (Dynamometer, amplifier and XY recorder) system. The rupture force of kernel was measured by the data acquisition system. The kernel was placed on the moving bottom platform and was pressed with stationary platform. Experiment was conducted at a loading velocity at 50 mm min-1. Figure 1. Biological material tets unit (B.M.T.U.) The terminal velocities (V) of kernel at natural moisture content were measured t using an air column. For each test, a sample was dropped into the air stream from the top of the air column, up which air was blown to suspend the material in South west J Hortic Biol Environ (2011) Physico-chemical properties of apricot kernels 5 the air stream. The air velocity near the location of the kernel suspension was measured by electronic anemometer having a least count of 0.1 m/s (Hauhout- Helmy 1990; Joshi et al. 1993). Geometric mean diameter (D ) and sphericity (Ø) values were found using the g following formula (Mohsenin 1970; Jain & Bal 1997). (2) D = (LWT)0.333 g (3) Ø = (LWT)0.333/L The coefficient of static friction was measured by using sheet iron, galvanized sheet iron and wood surfaces. For this measurement one end of the friction surface is attached to a endless screw. The kernel was placed on the surface and it was gradually raised by the screw. Vertical and horizontal height values were read from the ruler when the apricot kernel started sliding over the surface, then using the tangent value of that angle the coefficient of static friction was found. Baryeh (2001), Dutta et al. (1998), Suthar and Das (1996) have used similar methods. Chemical analyses: The some chemical compositions (moisture, crude fiber, crude oil, crude pro- tein and crude ash) were analyses according to AOAC (1984). Samples were homogenized and subjected to extraction for 6 h with petroleum ether (boiling range 30-60 °C) in a Soxhlet apparatus. The extracted oil was dried over anhy- drous sodium sulphate and the solvent was removed under reduced pressure in a rotary film evaporator. Oil percentages were determined by weight differ- ence. Ash was determined in a muffle furnace at 900 °C for 8 h (Demir & Özcan 2001). The nitrogen content estimated by the Kjeldahl method and was converted to protein content by using the conversion factor 6.25. The fiber and moisture were determined according to Demir and Özcan (2001). Determiation of mineral contents: About 0,5g of dried and ground apricot kernel was put into burning cup with 15 ml of pure HNO . The sample was incinerated in a MARS 5 microwave oven at 3 200 °C. Distilled deionized water and ultrahigh-purity commercial acids were used to prepare all reagents, standards, and walnut samples. After digestion treatment, samples were filtrated through whatman No 42. The filtrates were col- lected in 50 ml Erlenmayer flasks and analysed by ICP-AES. The mineral con- tents of the samples were quantified against standard solutions of known con- cantrations which were aralyzed concurrently (Skujins 1998). Working conditions ofICP-AES: Instrument: ICP-AES (Varian-Vista) RF Power: 0,7-1,5 kw (1,2-1,3 kw for Axial) Plasma gas flow rate (Ar): 10,5-15 L/min. (radial) 15 " (axial) Auzilary gas flow rate (Ar): 1,5 " Viewing height: 5-12 mm Copy and reading time: 1-5 s (max. 60 s) Copy time: 3 s (max. 100 s) South west J Hortic Biol Environ (2011) 6 Gezer, I. et al. Statistical analyses: Results of the research were analysed for statistical significance by analysis of variance (Salem& Salem 1973). This research was performed by three duplicates with a replicate. RESULTS AND DISCUSSION Physical properties The mass, length, width, thickness, geometric average diameter and sphericity values of the apricot kernels were given in Table 1. The fre- quency distributions of these kernels with respect to dimensional proper- ties were determined. Table 1. Dimensional properties of apricot kernels. Cultivars Properties Çataloglu Hacihahloglu Hasanbey Kabaaşı Sogancı Moisture content, (%) db. 2.98 2.18 2.46 2.47 3. 25 Mass, (g) 0.49±0.007 0.45±0.006 0.58±0.007 0.49±0.0OS 0.46±0.005 Length, (mm) 17.09±0.11 17.2±0.1O lS.44±0.08 17.07±0.13 13.96±0.06 Width, (mm) 9.32±0.06 8.98±0.05 10.30±0.58 9.81±0.08 10.69±0.05 Thickness, (mm) 6.37±0.05 6.19±0.04 5.62=0.04 5.56±0.05 6.23±0 05 Geo. Me. Dia, (mm) 10.04±0.05 9 85±0.04 10.2I±0.04 9 75±0.06 9 75±0.04 Sphericity 0.59±0.003 0 57±0.003 0 55±0.002 0.57±0.003 0 69±0.002 At 2.98 % moisture level, 96% of Çataloğlu apricot kernels were be- tween 0.35g and 0.60g in weight, 95% of those were between 15mm and 18.50 mm in length, 93% of those between 8.50 and 10 mm in width, and 96% of those between 5.50 mm and 7 mm in thickness. By establishing L/W, L/T, L/M, L/0 and L/Dg relationships between length, width, thick- ness, mass, sphericity and geometric average diameter values has been determined. This relationship was found to be as the follows. L=1.834xW= 2.683x T=34.180xM= 28.966x Ø=1.702xDg At 2.18 % moisture level, 97% of Hacıhaliloğlu apricot kernels were be- tween 0.35g and 0.55g in weight, 93% of those were between 15.5mm and 18.50 mm in length, 96% of those between 8 mm and 9.5 mm in width, and 93% of those between 5.5 mm and 7 mm in thickness. By establishing L/W, L/T, L/M, L/0 and L/Dg relationships between length, width, thickness, mass, sphericity and geometric average diameter values has been determined. This relationship was found to be as the follows. South west J Hortic Biol Environ (2011) Physico-chemical properties of apricot kernels 7 L=1.916xW= 2.780x T=38.240xM= 30.192x Ø=1.747xDg At 2.46% moisture level, 94% of Hasanbey apricot kernels were be- tween 0.45g and 0.68g in weight, 96% of those were between 16.50 mm and 19.50 mm in length, 98% of those between 8.77 mm and 11 mm in width, and 98% of those between 4.5 mm and 6 mm in thickness. By es- tablishing L/W, L/T, L/M, L/0 and L/Dg relationships between length, width, thickness, mass, sphericity and geometric average diameter values has been determined. This relationship was found to be as the follows. L=1.790xW= 2.283x T=31.793xM= 33.527x Ø=1.793xDg At 2.47% moisture level, 98% of Kabaaşı apricot kernels were between 0.35g and 0.70g in weight, 97% of those were between 14.5mm and 19 mm in length, 97% of those between 8.5 mm and 11 mm in width, and 98% of those between 4.5 mm and 6.5 mm in thickness. By establishing L/W, L/T, L/M, L/0 and L/Dg relationships between length, width, thickness, mass, sphericity and geometric average di- ameter values has been determined. This relationship was found to be as the follows. L=1.741xW= 3.072x T=34.857xM= 29.965x Ø=1.752xDg At 3.25% moisture level, 96% of Soğanoğlu apricot kernels were be- tween 0.35 g and 0.50 g in weight, 95% of those were between 12.5mm and 14.5 mm in length, 95% of those between 10 mm and 11.75 mm in width, and 99% of those between 5 mm and 7 mm in thickness. By es- tablishing L/W, L/T, L/M, L/0 and L/Dg relationships between length, width, thickness, mass, sphericity and geometric average diameter values has been determined. This relationship was found to be as the follows. L=l.3O6xW=2.24lxT=3O.347xM=\9.942x0=lA3OxDg The dimensional properties of apricot kernels used in the experiments were given in Table 2. It was found that L/T relationship in Hacıhaliloğlu was statistically meaningful at 5% level. L/T relationship in Hasanbey, Ka- baaşı, Çataloğlu and Soğanoğlu apricot kernel types were statistically not meaningful. It was found that L/W, L/M, L/0 and L/Dg relationships in Apricot type kernels: the whole relationships were statistically meaningful at 1% level. The volume, bulk density, kernel density, porosity, terminal velocity, projected area, rupture strength and static friction coefficent values of ap- ricot pits were given in Table 3. According to these results, çataloğlu type apricot kernel has the highest volume with 0.58 cm3. It was fol- lowed by Soğanoğlu, Hasanbey, Kabaaşı, and Hacıhaliloğlu type apricot kernels. The highest bulk density value, 574.62 kg/m3, was found in Hacı- haliloğlu types; and it was followed by hasanbey, Kabaaşı, Çataloğlu and Soğanoğlu types. The highest kernel density value, 1117.02 kg/m3, was South west J Hortic Biol Environ (2011) 8 Gezer, I. et al. found in Hasanbey types, and it was followed by Kabaaşı, Hacıhaliloğlu, Çataloğlu, and Soğanoğlu types. The highest porosity value was found to be 49.95 % in Hasanbey type; and the lowest porosity value was found Table 2. Tlıe correlation coefficient of apricot kernels. Degrees of Correlation Cultivars Partıculai's Ratıo freedom coefficient Çataloğlu L/W 1.834 98 0.614** L/T 2 .683 98 0.095 L/M 34.180 98 0.7526** L/Ǿ 28.966 98 -0.641** L/Dg 1.702 98 0.721** Hacıhaliloğlu L/W 1.916 98 0.685** L/T 2.780 98: 0.157* L/M 33.24 98 0.798** L/Ǿ 30.192 98 -0,615** L/Dg 1.747 98 0.775** Hasanbey L/W 1.790 98 0.580** L/T 2.283 98 0.148 L/M 31.793 98 0.746** L/Ǿ 33.527 98 -0.411** L/Dg 1.793 98 0.707** Kabaaşı L/W 1.741 98 0.760** L/T 3.072 98 0.129 L/M 34.857 98 0.807** L/Ǿ 29.965 98 -0.627** L/Dg 1.752 98 0.808** Soğancı L/W 1.306 98 0.525** L/T 2.241 98 0.140 L/M 30.347 98 0.758** L/Ǿ 19.942 98 -0.525** L/Dg 1.432 98 0.661** **P>0.01; * P>0.05 to be 39.98 % in Soğanoğlu type. The highest terminal velocity value was found to be 6.31 m/s in Hacıhaliloğlu type; and the lowest termi- nal velocity value was found to be 5.82 m/s in Hasanbey type. Again, the highest projected area value was found to be 1.60 cm2 in Hasanbey type; and the lowest projected area value was found to be 1.13 cm2 in ha- cıhaliloğlu type. The highest static friction coefficent value was found to be 0.516 in Hasanbey type on wooden surfaces; and the lowest static South west J Hortic Biol Environ (2011) Physico-chemical properties of apricot kernels 9 friction coefficent value was found to be 0.275 in Çataloğlu type on gal- vanized sheet. The rupture strength values found to be the highest at the thickness dimension in all types. The shear force values at length di- mension and width dimension followed this highest value in all types except Çataloğlu types. This difference in Çataloğlu type stems from type difference. Table 3. Some physical properties of apricot kernels. Properties / Çataloğlu Hacıhaliloğlu Hasanbey Kabaaşı Soğanoğlu Cultivars Volume (cm3) 0.58±0.04 0.45±0.02 0.49±0.02 0.47±0.03 0.51±0.02 Bulk density 561.16±5.48 574.62±10.13 571.94±6.22 564.74±4.74 555.45±2.03 (kg/m3) Kernel density 961.57±39.07 1023.15±23.431117.02±35.51088.6±28.51 930.89±34.56 (kg/m3) Porosity (%) 43.01±1.51 43.81±1.13 49.95±1.36 48.15±1.38 39.98±1.41 Terminal velocity 6.27±0.17 6.31±0.16 5.82±0.14 6.28±0.22 6.18±0.12 (m/s) Projected area 1.29±0.03 1.13±0.03 1.60±0.08 1.42±0.06 1.25±0.02 (cm2) Rupture strength Length 46 ±0.90 40.17±4.19 43.55±2.51 47.31±1.68 49.55±1.88 Width 43.17±1.88 53.18±3.39 55.60±3.95 61.05±2.19 60.06±3.34 Thickness 87.22±12.44 94.55±9.12 155.13±15.69125.35±16.17 114.02±11.15 The coefficient static friction Sheet iron 0.478±0.022 0.429±0.014 0.439±0.010 0.443±0.015 0.436±0.010 Galvanized sheet 0.275±0.010 0.291±0.13 0.314±0.011 0.287±0.010 0.321±0.011 iron Wood 0.492±0.024 0.461±0.025 0.516±0.036 0.474±0.022 0.505±0.037 The chemical properties The composition of the five apricot cultivar kernels investigated is pre- sented in Table 4. The cultivars showed relatively low differences. For the production of apricot juice of good quality, Soğanoğlu, Hacıhaliloğlu, Çata- lağlu, Kabaaşı and Hasanbey are ideal cultivars. So, they have high con- tents of kernel as by apricot product. In the present investigation kernel material of apricot from Malatya were investigated regarding the some chemical composition as well as the mineral contents. Crude protein, crude oil, crude fibre, ash and dry matter contents of all fruits were determined between 15.7 to 18.3%, 28.26 to 42.48%, 15.3 to 17.1%, 2.91 to 3.83% and 96.75 to 97.82%, respectively. The protein, fibre and ash values of several kernels were found partly similar, having South west J Hortic Biol Environ (2011) 10 Gezer, I. et al. protein contents in a narrow range. The ash contents of apricot kernels established between 2.91% (Hacıhaliloğlu) to 3.83% (Çataloğlu). Özcan (2000) determined oil (46.30-51.40%), crude protein (23.58-27.70%), crude fibre (13.49-17.98%), moisture (4.91*6.66%) and ash (2.10-2.67%) Table 4. Some chemical composition of several apricot kernels Cultivars Properties Soğanoğlu Hacihaliloğlu Çataloğlu Kabaaşı Hasanbey Moisture, (%) 3.25±0.73 2.18±0.27 2.98±0.31 2.47±0 17 2.46±0.41 Crude oil, (%) 41.77±1.13 42.43±2.32 30.82±1.97 28 26±1.13 29.47±1.74 Crude protein (%) 18.3±1.27 17.6±1 21 16.3±1.11 15 7±1.32 16.1 ± 1. 74 Crude fibre, (%) 15.7±2.14 15.3±1.81 16.2±1.19 17 1±2 07 16.3±1.63 Crude ash, (%) 3.27±0.74 2.91±0.18 3.83±0.27 3.48±0.31 3.71±0.63 contents of four apricot kernels collected from Malatya provinces. Protein and oil concentrations of all kernels are low from Amar (24.1% and 50.9%) and Moorpark (20.6% and 52.0%) by Abd-Aal et al.(1986a,b). Salem and Salem (1973) reported 53.17% and 55.96% oil in Egyptian (sweet) and Egyptian (bitter) apricot kernels, respectively. Also, Joshi et al.(1993) established 3.4% moisture, 44.6% oil, 20.2% protein, 18% fibre and 2.3% ash in Chavaru apricot kernel. Mineral contents of kernels are given in Table 5. Ca, K, Mg, Na and P were established as major minerals in kernels. Others were determined at minor levels. The phosphor levels of kernels ranged between 4967.5 (Kabaaşı) and 9387.2% ppm (Soğanoğlu). The highest minerals were K, P and Ca. Potassium con- tenst was found the highest (91909.4 ppm) in Soğanoğlu kernel. In a pre- vious study, mean mineral contents of apricot kernel varieties were found to be between 2.75 -3.68% for Na, 1.06-2.94 ppm for P and 0.35 - 0.64 ppm for K (Özcan 2000). The K, Na, Ca, P and Mg levels are adequate. Moisture, crude oil, crude protein, crude fibre and crude ash values and mineral contents in apricot kernels are affected mainly by variety. As a result, the present study showed the kernels of the researched species of Prunus fruits from Turkey to be a potential source of valuable oil which might be used for edible and other industrial applications. In addition, knowledge of the mineral contents, as kernels is of great interest. Due to limited number of samples determined in this work, this conclusion should be verified several apricot kernel samples. Future work also consider other compounds and antinutrient factors of these and another apricot kernels which may be used as food. So, sweet kernels can be used as baked products and roasted titbits. South west J Hortic Biol Environ (2011)