LWT - Food Science and Technology

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LWT - Food Science and Technology

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E ﬀ ects of fractionation technique on triacylglycerols, melting and

crystallisation and the polymorphic behavior of bambangan kernel fat as cocoa butter improver

M.R. Norazlina

^a

, M.H.A. Jahurul

^a,^∗

, M. Hasmadi

^a,^∗∗

, M.S. Sharifudin

^a

, M. Patricia

^a

, J.S. Lee

^a

, H.M.S. Amir

^a

, A.W. Noorakmar

^a

, I. Riman

^b

aFaculty of Food Science and Nutrition, Universiti Malaysia Sabah, 884000, Kota Kinabalu, Sabah, Malaysia

bSchool of Chemistry and Environment, Faculty of Applied Sciences, Universiti Teknologi, MARA, Malaysia

A R T I C L E I N F O

Keywords:

Mangifera pajangfat Stearin fractions Thermal properties DSC

Confectionery fat

A B S T R A C T

Cocoa butter improver (CBI) is typically composed of high melting symmetrical triacylglycerols (TAGs) that aid in the hardness of chocolate products in tropical/subtropical regions. High-melting symmetrical TAG (1,3-distearoyl-2-oleoyl-glycerol, SOS) rich fats were produced by two-stage acetone fractionation. Diﬀerent chroma- tographic and thermal techniques were used to determine TAGs, thermal properties, and polymorphic behavior of each bambangan kernel fat (BKF) fraction. Theﬁrst (S-1) and second (S-2) stearins composed of 55.83% and 64.70% symmetrical SOS were the valuable CBIs produced from the fractionated BKF. The stearin fractions also melted and crystallised rapidly at high temperatures with one maximum peak starting at 20.30–21.74 °C and ending at 38.72–42.45 °C (melting), and another starting at 17.05–18.46 °C and ended at 5.63–8.20 °C (crystallisation). In comparison with pure BKF and commercial cocoa butter (CB), the stearins showed sharper melting curves and higher melting properties. The stearins also exhibitedβ-polymorphic form which was similar to that of CB. Results suggested that the stearins were suitable to be applied as CBI to improve the melting properties and the availability of confectionery products in tropical/subtropical countries.

1. Introduction

Cocoa butter (CB) is mainly composed of 1,3-di-stearoyl-2-oleoylglycerol (SOS), 1-palmitoyl-2-oleoyl-3-stearoyl-glycerol (POS), and 1,3- dipalmitoyl-2-oleoylglycerol (POP) (symmetrical monounsaturated triacylglycerols [TAGs], SUS-TAGs), and it is the most favorable in- gredients in the confectionery industry, especially in chocolate manufacturing (Jin, Akoh, Jin, & Wang, 2018a). CB which is extracted from dried cocoa beans, has become the most expensive ingredient in chocolate formulation (Afoakwa, 2014) because of the increasing demand for chocolate worldwide causes a shortage in CB supply. CB also has a low melting temperature (33.8 °C) which causes softening problems and limits its availability and consumption in tropical and subtropical countries (Jin et al., 2017a). Thus, cocoa butter improvers (CBIs) with similar high melting, Hm-symmetrical TAGs composition such as SOS, are recommended to increase the hardness of chocolate (Beckett, 2000, pp. 102–124; Gunstone, 2011;Tran et al., 2015). However, SOS and POS rich CBIs are diﬃcult to ﬁnd and expensive than cocoa butter

equivalent (CBE) (Beckett, 2000, pp. 102–124). Therefore, Hm-symmetrical TAGs can be obtained from the fractionation of natural resources such as sal fat, kokum butter, shea butter, illipe butter, mango kernel fat, sunﬂower oil, and bambangan kernel fat; some of this fats contain SOS (Bootello, Hartel, Garcés, Martínez-Force, & Salas, 2012;

Gunstone, 2011;Jin et al., 2016).

Bambangan is a type of wild mango that comes from the Anacardiaceae family and is similar to commercial mango. The wastes by-product of bambangan, in particular, the kernel, makes up 27% of the fruits’total weight and contains approximately 9.9% fat on a dry basis (Jahurul et al., 2018a,b). This bambangan kernel fat (BKF) has attracted considerable attention among scientist because of its simi- larity to CB-like fats such as mango fat, shea butter, kokum butter, sal butter, and illipe butter (Al-sheraji, Ismail, Manap, Mustafa, & Yusof, 2012;Jahurul et al., 2018a,2018b,2019). BKF is typically a complex mixture of TAGs constituted by fatty acids (i.e., palmitic; 8.4%, stearic;

36.4%, oleic; 44.5% and linoleic; 5.4%) that cause diﬀerences in their physicochemical and thermal properties. Given to its one maximum,

https://doi.org/10.1016/j.lwt.2020.109558

Received 22 January 2020; Received in revised form 17 April 2020; Accepted 5 May 2020

∗Corresponding author.

∗∗Corresponding author.

E-mail addresses:[email protected](M.H.A. Jahurul),[email protected](M. Hasmadi).

Available online 08 May 2020

T

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BKF also shows similar melting properties to CB-like fats. Therefore, the reported main TAGs of BKF include POP (7.37%), POS (11.6–11.48%), SOS (28.53–28.7%), and SOO (11.2%) (Jahurul et al., 2018b,2019).

BKF with a high level of SOS (> 65%) can be used directly as CBI without undergoing fractionation for preparing high melting BKF stearin. Meanwhile, mango kernel fat (MKF) with SOS of < 50% is suggested as CBE sources (Solís-Fuentes & Durán-de-Bazúa, 2011;Tran et al., 2015). Thus, pure BKF (< 50% SOS) can be fractionated by single or multistage fractionation to produce fractions of stearin (solid) and olein (liquid) with diﬀerent TAGs.

Fractionation is a common modification technique that has been used in the edible industry to modify the properties of crude fats and oils through physical separation or crystallisation by producing high- melting pure crystals with improved functionality. The European Union (Directive 2000/36/EC) also allowed fractionation in the edible industry as the only lipid modification technique for CBE and CBI production due to safety concerns. Therefore, pure BKF is fractionated by two stages acetone fractionation. Acetone is often used as a solvent due to high crystal separation efficiencies for specialty fat production (Kellens, Gibon, Hendrix, & De Greyt, 2007). Acetone is suitable for obtaining symmetrical triacylglycerols-rich fats due to its polarity that causes the removal of other components such as diacylglycerols, triacylglycerols and free fatty acid in the liquid fractions (Timms, 2006).

Therefore, the present study aimed to determine the TAGs, thermal properties (melting and crystallisation), and polymorphic behavior of BKF fractions produced by two stages of acetone fractionation to identify their potential application. This information would be bene- ﬁcial for the utilisation of BKF and its fractions as a high-quality fat resource with improved melting properties.

2. Material and methods 2.1. Materials

Mature bambangan fruits were collected from an orchid in Tenghilan (Tuaran), Sabah. Bambangan fruit was cut to obtain the kernels. Then, the kernel was washed with water, cut into small pieces, dried at 50 °C and ground into powdered form. The moisture content was found to be 6.13 ± 0.60%. TAG standards were purchased from Sigma-Aldrich, and acetone (SYSTERM), acetonitrile,n-hexane (Merck, Germany) were obtained from Kota Kinabalu Sabah, Malaysia.

2.2. Bambangan kernel fat extraction

According to American Oil Chemists’Society (AOCS, 2009), BKF was extracted using the Soxhlet with slight modiﬁcation.

2.3. BKF stearin fractions preparation by two-stage acetone fractionation

The two-stage fractionation of BKF using acetone was performed at 18 °C according to the method described byJin et al. (2017b) with slight modiﬁcation. Approximately, 100g of BKF was melted at 70 °C–80 °C for complete melting and removal of any crystal memories.

Then, the melted BKF was mixed with warm acetone (preheated 40 °C) at a 1:5 (w/v) ratio. Preliminary fractionation showed that BKF achieved stable fractionation after 180 min. Theﬁrst fractionation was completed at 180 min to obtain theﬁrst stearin (S-1) and olein (O-1) fractions.

The stearin was separated by vacuumﬁltration, and the remaining solvent in the fractions was evaporated using a rotary evaporator (HEIDOLPH 115 LABORTA 4001). The stearin was maintained at 15 °C for 180 min for further fractionation. S-1 was further fractionated to obtain additional saturated second stearin (S-2) and olein (O-2) fractions. Both processes were carried out in the same manner and in triplicate. The yields of the fractions were recorded and shown inFig. 1.

2.4. Determination of melting and crystallisation characteristics by DSC

Differential scanning calorimetry (DSC, Pyris 4000; Perkin-Elmer, USA) was used to monitor the melting and crystallisation behavior of each BKF fraction according to AOCS Official Method cj1–94 (AOCS, 2009) with slight modification. To erase fat crystallographic memory, all the stearin fractions of BKF were melted at 100 °C, and the olein fractions were melted at 80 °C. The modified procedure is described in our previous study (Jahurul et al., 2019).

2.5. Determination of triacylglycerols by high performance liquid chromatography (HPLC)

According to AOCS Oﬃcial Method Ce5b–89 (AOCS, 2009) with slight modiﬁcation, the TAGs of BKF fractions were analysed by high- performance liquid chromatography (HPLC, Series 1200; Agilent, USA).

The Agilent HPLC instrument with Quaternary Pump (Agilent HPLC Series 1200, Degasser Model G1322A, Quaternary Pump Model G1311A, RI Detector Model G1362A), and a LiChrospher 100 RP-18e HPLC column (4 mm i.d. × 250 mm length) was used to determine TAGs of BKF fractions. The modiﬁed procedure is described in our previous study (Jahurul et al., 2019).

2.6. Polymorphic behavior by X-ray diﬀraction (XRD)

The polymorphic form of each fraction crystals was determined using X-ray diﬀraction (XRD, PANanalytical X'Pert Pro diﬀractometer;

Philips PW3040/60, USA) according to the established method of AOCS Cj 2–95 (AOCS, 2009). Prior to the experiment, BKF fractions were melted at 80 °C in an oven and stabilised for 24 h in an incubator at 25 °C. The analysis was conducted on a pan analytical diﬀractometer using Bragg-Brentano geometry (θ:2θ) with Cu kα radiation of λ= 1.54178 Å; Voltage of 40 kV and current of 40 mA. The mea- surements were obtained with steps of 0.02° in 2θand acquisition time of 2 s, with scans from 5 to 40° (range 2θ). The polymorphic form was identiﬁed on the basis of the characteristics of short spacings of each fraction crystals. The relative number of the crystal types was determined by the relative intensity of the short spacings reported by Marangoni and McGauley (2003)andSchenk and Peschar (2004).

2.7. Statistical analysis

All analyses were conducted in triplicate and reported as standard mean ± standard deviation. ANOVA and Tukey tests were performed using SPSS version 24.0 for signiﬁcant diﬀerent (p < 0.05).

3. Results and discussion

3.1. Eﬀect of fractionation on DSC melting thermograms

Melting profiles of the pure BKF and its fractions are shown inFig. 2 (a)-(b) andTable 1. The BKF fractions were significantly (p < 0.05) affected by the fractionation. The BKF and the stearin fractions exhibited one single peak, with the stearin peak becoming sharp and shifting to high temperatures after acetone fractionation. The melting ranges also become narrow, which is a suitable property in chocolate manufacturing because it facilitates tempering (Beckett, 2008). In the present study, a gradual increment was observed in the melting onset, offset, and enthalpy for S-1 and S-2 after fractionation (Table 1). The pure BKF was melted slowly, whereas the stearin fractions were melted rapidly at high temperatures (Fig. 2a). S-1 and S-2 showed one maximum peak for melting, with the maximum temperature ranges from 20.30 to 38.72 °C and from 21.74 to 42.45 °C, respectively. This result indicated that most of the low melting TAGs (POO, SOO, and OOO, etc.) were removed during fractionation. These fractions also possessed higher enthalpies than pure BKF and its olein fractions. This result

M.R. Norazlina, et al. LWT - Food Science and Technology 129 (2020) 109558

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indicated that additional energy was required to breakdown crystals into a liquid and that such requirement is correlated with high SMP (34.3 and 36.3 °C), respectively. Thisfinding was in accordance with that ofJin et al. (2017c), who studied the melting thermogram of MKF fractions using DSC and reported two maxima (Fraction I and II) at 25.8–35.9 °C and 28.1–38.0 °C. Solís-Fuentes and Durán-de-Bazúa (2004),Jahurul et al. (2014), andSonwai, Kaphueakngam, and Flood (2014)also reported similar melting profiles of MKF, with the highest maximum ranging from 34.6 to 42.2 °C. S-1 and S-2 also exhibited comparable melting properties as CB. Thus, BKF fractions (S-1 and S-2) are considered as ideal CBIs for heat-resistance materials in the confectionery industry. These materials can be used as a blending component for chocolate formulation. The stearins also have the potential to be applied as a confectionery fat when high melting point fat is required for the industry (Jin et al., 2017c). Acetone fractionation im- proves the thermal properties of confectionery fats and produces CBI (heat-resistance CBE) resources. Natural CBIs from fat vegetable resources are difficult to obtain due to intermittent crop availability.

Thus, natural high melting fat for confectionery use can be produced by the fractionation of pure BKF. Relative to stearin, the olein fractions that exhibited a broad melting range with unseparated two maxima compared to those stearin fractions. These conditions were due to the fact that the olein fraction contained a wide range of TAGs and low- melting TAGs (i.e., SOO, OOO, POO, etc.).

3.2. Eﬀect of fractionation on DSC crystallisation thermograms

Fig. 3(a) and (b) shows the effects of fractionation on the DSC crystallisation curves of pure BKF and its fractions. The onset and offset of S-1 and S-2 were significantly (p < 0.05) higher than those of pure BKF and olein fractions. The pure BKF crystallised slowly. Meanwhile, its fractions, in particular stearin fractions (S-1 and S-2) crystallised rapidly with decreasing temperatures. Although, pure BKF exhibited a similar exothermic crystallisation peak at 13.16 °C (started at 15.32 °C, ended at 1.45 °C) as MKF, the value was lower compared to the CB (14.4 °C, and from 17.3 to−15.8 °C) and CBE (16.6 °C, and from 18.9

to−16.7 °C) reported byJin et al. (2017c). After fractionation, S-1 and S-2 showed single crystallisation peaks at 17.05 to 5.63 °C and 18.64 to 8.20 °C, respectively. This trend was in agreement with the crystallisation behavior of MKF and its fractions produced by three-stage fractionation byJin et al. (2017c). Similar crystallisation curves for MKF were reported by Solís-Fuentes and Durán-de-Bazúa (2004), Sonwai et al. (2014),Jahurul et al. (2014), andJin et al. (2017b). In their study, a single peak started at 17.18 °C and ended at−24.32 °C.

Meanwhile, Solís-Fuentes and Durán-de-Bazúa (2004), Sonwai et al.

(2014), andJahurul et al. (2014)reported a single peak from 14.64 to 18.98 °C and from−24.27 to 24.32 °C. The crystallisation range for pure BKF, and stearin decreased from 13.87 °C (15.32–1.45 °C) to 10.23 °C (18.46–8.20 °C) due to the presence of high-melting TAGs in the stearin fractions. The presence of high melting TAGs reduces the crystallisation ranges in the fat fractions; thus, it solidiﬁes easily at the temperature below its melting point (SMP; 34.3–36.3 °C). Therefore, the stearin fractions showed sharp solidiﬁcation intervals relative to CB.

This result indicates that CBI could be produced as hard fat resource in the confectionery industry.

By contrast, the olein fractions showed a low crystallisation temperature and would not solidify until the temperature falls below 10 °C.

These fractions exhibited favorable liquidity at 25 °C. The olein fractions showed a maximum peak at 4.35, 6.87 and 8.01 °C with Fraction VI has the highest crystallisation ranges of 16.8 °C (8.34 to−8.43 °C).

This is due to the high melting TAGs were removed from this olein, leaving the low melting TAGs that cause the olein to liquidify at room temperature and crystallizes at shallow temperature.

3.3. Triacylglycerols (TAGs)

TAGs composition is often known to crystallise in different polymorphic form depending on the process conditions and chemical compositions such as heat, mass, momentum transfer, and fatty acids (Marangoni & McGauley, 2003). This work is thefirst report on the TAGs of BKF stearin fractions (Table 2). The melting profiles indicated that the stearin fractions exhibited similar maximum peak as CB, given Fig. 1.Bambangan kernel fat stearin fractions produced by acetone fractionation.

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the presence of high melting TAGs. Thus, the stearin fractions were selectively studied for their composition. The TAGs in the fractions were signiﬁcantly (p < 0.05) aﬀected by the fractionation. POS (11.93–13.61%), SOO (11.77–26.88%), and SOS (40.71–64.70%) were the dominant monounsaturated TAGs found in the BKF and its

fractions. The fractions also contained a definite amount of low melting TAGs, such as POO and OOO, in the range of 1.75–4.57% and 1.81–5.89%, respectively. Relative to pure BKF, the stearin fractions showed a significant increment in POS and a gradual decrease in the low melting TAGs of OOO, POO and SOO. This result could be Fig. 2.Differential Scanning Calorimetry (DSC) melting curve of pure bambangan kernel fat (BKF),first stearin (S-1) and second stearin (S-2) (a),first (O-1) and second olein (O-2) (b).

Table 1

Thermal properties (melting and crystallisation) of bambangan kernel fat fractions.

Fats Melting properties Crystallisation properties

Onset Temp (°C) Offset Temp (°C) Enthalpy (J/g) Maximum Peak (°C) Onset Temp (°C) Offset Temp (°C) Enthalpy (J/g) Maximum Peak (°C) BKF 16.26 ± 0.02^d 37.64 ± 0.05ê 65.74 ± 0.00ê 30.98 ± 0.01ê 15.32 ± 0.02ê 1.45 ± 0.00^c −76.15 ± 0.00^c 13.16 ± 0.02ê S-1 20.30 ± 0.00ê 38.72 ± 0.07^f 75.34 ± 0.03^f 32.18 ± 0.01^f 17.05 ± 0.07^f 5.63 ± 0.03ê −89.00 ± 0.00^b 13.95 ± 0.04^f O-1 −10.35 ± 0.02^c 21.41 ± 0.02^c 44.52 ± 0.03^b 14.36 ± 0.04^c 6.01 ± 0.01â 0.71 ± 0.02^b −49.91 ± 0.00^g 4.35 ± 0.02â S-2 21.74 ± 0.00^f 42.45 ± 0.02^g 85.24 ± 0.00^g 33.84 ± 0.05^g 18.46 ± 0.02^g 8.20 ± 0.02^g −92.85 ± 0.04â 15.81 ± 0.01^g O-2 −11.92 ± 0.03â 21.01 ± 0.00^b 39.75 ± 0.00â 14.01 ± 0.02^b 8.13 ± 0.04^b 2.67 ± 0.01^d −67.82 ± 0.03^d 6.87 ± 0.01^b MKFâ 15.1 32.7 56.7 25.6 17.0 −20.0 54.2 13.6 CB^b −25.97-14.94 27.81-37.73 – – −5.20–17.71 −26.2–5.59 – –

BKF: Bambangan kernel fat, F(I): Fraction I, F(II): Fraction II, F(III): Fraction III, F(IV): Fraction IV, F(V): Fraction V, F(VI): Fraction VI, CB: Cocoa butter.

Values are the mean ± standard deviation of three replicate; means with different letter within a column are significantly different (p < 0.05) as measured by Tukey test.

a Sonwai, Kaphuekngam & Flood (2014);Jahurul et al. (2014);Jin et al. (2017c).

b Khairy & Tajul (2016);Zzaman, Issara, Easa and Yang (2017).

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Fig. 3.Differential Scanning Calorimetry (DSC) crystallisation curve of pure bambangan kernel fat (BKF),first stearin (S-1) and second stearin (S-2) (a),first (O-1) and second olein (O-2) (b).

Table 2

Triacylglycerols composition of bambangan kernel fat fractions produced by two-stage fractionation.

TGs BKF S-1 S-2 MKF^a CB^b

OLL 0.202 ± 0.01^b 0.108 ± 0.02^a 0.061 ± 0.01^a – –

PLL 0.159 ± 0.00^b 0.063 ± 0.02^a 0.031 ± 0.00^a – –

OLO 0.915 ± 0.01^c 0.499 ± 0.01^b 0.283 ± 0.00^a 0.47-2.28 –

POL 0.707 ± 0.01^c 0.385 ± 0.01^b 0.213 ± 0.00^a – –

PLP 0.162 ± 0.00^b 0.109 ± 0.01^a 0.074 ± 0.01^a 0.07-0.57 –

OOO 5.889 ± 0.08^c 3.186 ± 0.00^b 1.812 ± 0.02^a 2.5–8.63 0.2-0.9

POO 4.568 ± 0.24^c 2.734 ± 0.01^b 1.745 ± 0.03^a 1.76-10.8 1.2–5.5

POP 0.751 ± 0.02^c 0.604 ± 0.02^b 0.491 ± 0.00^a 1.16-8.9 13.8–18.6

SOO 26.876 ± 0.08^c 17.250 ± 0.04^b 11.771 ± 0.15^a 8.1–30.8 1.7–8.4

POS 11.937 ± 0.07^a 13.521 ± 0.05^b 13.612 ± 0.24^b 5.7–16.56 34.6–41.6

SOS 40.709 ± 0.00^a 55.830 ± 0.06^b 64.702 ± 0.93^c 14.3–55.44 23.7–28.5

SSS 0.431 ± 0.05^a 0.734 ± 0.00^a 0.849 ± 0.13^b – –

SSP 0.486 ± 0.05 0.651 ± 0.14 – –

BKF: Bambangan kernel fat, S-1: First tearin 1, S-2: Second stearin, CB: Cocoa butter.

Values are the mean ± SD of three replicate; means with in a row with different letters are significantly different (p <0.05) as measured by Tukey test.

a Jin et al. (2017a,b);Jin et al. (2016);Jahurul et al. (2014);Gujinkar (2005).

b Jin et al. (2017a,b);Lipp and Anklam (1998).

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explained the changes in the melting and crystallisation characteristics of the stearin fractions. Thus, these fats have high thermal properties that could be utilised in the confectionery industry as a heat-resistance fat resource. In tropical countries, high-melting fat is preferred in im- proving the melting properties of chocolate products at a certain temperature. For example, by adding high-melting SOS- or SOA-rich fats into CB-fat based, the melting proﬁles can be increased several degrees higher than that of natural CB without leaving waxiness (Beckett, 2000, pp. 102–124;Salas, Bootello, Martinz-Froce, & Garces, 2011). Fats with similar POS (13.2–16.0%) and SOS (53.9–59.0%) composition to these stearin have been applied as confectionery fat ingredient in the industry (Gunstone, 2011;Tran et al., 2015).

SOO (< 27.0 °C), POO (< 21.9 °C) and OOO has low melting point in their most stable form, while POS and SOS have high melting points of 23.5–43.0 °C and 19.5–35.5 °C respectively, depending on their polymorph form (α→β) (Arishima, Sagi, Mori, & Sato, 1991;Koyano, Hachiya, & Sato, 1992;Minato et al., 1997). The SOS of stearin fractions was signiﬁcantly (p < 0.05) higher than those of pure BKF (28.7–40.71%), MKF (29.99–55.44%) and CB (23.7–28.5%) (Jahurul et al., 2018;Jin et al., 2016). This result is due to the polarity of the symmetrical monounsaturated SOS in the BKF which caused it to crystallise in the acetone compared to the non-symmetrical TAGs (Kang, Kim, Lee, & Kim, 2013). The trend for the changes in the TAGs of BKF stearin fractions was in agreement with that of the fractionated MKF (Jin et al., 2017a,c). Thus, the stearin fractions produced by the two-stage acetone fractionation can be applied as SOS-rich fats.

3.4. Polymorphism of BKF fractions

This work is thefirst to investigate the polymorphic behavior of pure BKF and its fractions produced by two-stage fractionation. The polymorphism of fats and oils is closely related to their crystallisation state and is crucial for their industrial application. Fats are biologically a mixture of natural TAGs at their pure state, and they can crystallise in different polymorphic form (α,β’,β,ɣ) depending on the processing condition and their chemical composition (Marangoni & McGauley, 2003). Each polymorphic form has a unique molecular organization, stability, and melting point (Solís-Fuentes, del Rosario, Hernandez, del Carmen, & Durán-de-Bazúa, 2005). Thus, the polymorphism characteristics of BKF and its stearin fractions were determined to identify the potential applications of fat fractions to the confectionery industry, specifically as CBI. The results could aid the production of fat that are essential for the manufacturing of high-quality chocolate and promote the formation and stabilisation of polymorphic form in CB.

Fig. 4shows the diffraction pattern and evaluated short spacings for CB and BKF stearin fractions. The polymorphic behavior of BKF fractions was significantly (p < 0.05) affected by the acetone fractionation. The changes in the XRD patterns of BKF stearin fractions were remarkable. These fat samples showed a considerable resemblance to CB, especially S-1. Thefingerprint region of CB and BKF fractions phase were identified at 2θ from 15° to 26° as described by Schenk and Peschar (2004)(λ= 1.5418 Å,d-spacing values of 3.0–6.0 Å, at 2θ ranging from 15° to 30°), andMarangoni and McGauley (2003). The atom molecules of TAGs were well-ordered and cause wavelength dis- persion; hence, the polymorph phase could be identified on the basis of the documented diffraction patterns (de Oliveira, Badan Ribeiro, dos Santos, Cardoso, & Kieckbusch, 2015). The TAGs were crystallised following the sequence of increasing stability, that is, α, β′ and β (deMan, 1994;deMan & deMan, 2001;Loisel, Keller, Lecq, Bourgux, &

Ollivon, 1998). The peak ofβ-form was evident at 19.5° (4.58 Å) on CB, BKF, S-1, and S-2, thus indicating that the fractionated fat had the ty- pical diﬀraction pattern ofβ-structure (Marangoni & McGauley, 2003).

These patterns were in line with those of the fully hydrogenated fats, soybean oil, crambe oil (predominant with 18 carbon atoms in the fatty acids), CB and MKF stearin and POMF (blended and interesteriﬁed) polymorphic behavior reported byBergel (2001)andJin et al. (2018b).

The diﬀraction pattern for BKF fractions indicated that the fractions crystallised in the same polymorphic form of CB during 1 h crystallisation (Sonwai et al., 2014). S–I showed a stable diﬀraction pattern as CB relative to the pure BKF that had a scattering intensity over time.

Meanwhile, S-2 exhibited similar diﬀraction pattern ofβ- andβ′- form with four scattered peak at 19.5°, 20.5°, 21.5° and 23° that are similar to the recommended CBE pattern and various polymorphic forms of CB as reported bySonwai et al. (2014)andMarangoni and McGauley (2003).

According todeMan and deMan (2001), the factors that could aﬀect the β′crystal formation in fat samples are the diversity of fatty acids and TAGs in fat samples.

Theβcrystal peak remained predominant in the S-1 and indicated that it is suitable as CB alternative for chocolate formulation (de Oliveira et al., 2015). Theβ-form had the highest melting point and was significant and stable relative to the other form with closest molecules arrangement; thus, this form is favorable (Solís-Fuentes et al., 2005). S- 2 showed a dominant peak ofβ′-form together with theβ-phase. Theβ′- crystal in S-2 was unstable asβcrystal; it is a metastable form that is more stable than αform (Hondoh & Ueno, 2016). This stearin also possessed the mixture of CB polymorphfingerprint region; thus, it can be used as a blending component with CB or other vegetable fat for producing new CBE in the confectionery industry. The dominant crystallisation form in the fat samples was promoted by the specific fatty acids in the glycerol molecules at which the fat with asymmetric TAGs possessβ’; by contrast fat with symmetrical TAGs tended to undergoβ- crystal formation (de Oliveira et al., 2015).

4. Conclusion

BKF stearin fractions produced by the two-stage acetone fractionation are beneﬁcial CBI fat resources which can increase the thermal properties of confectionery products in tropical/subtropical countries.

With the right proportion (whole/partial), BKF stearin fractions can be applied as natural fat resources for the manufacturing of heat-resistance confectionery fat with the desirable melting characteristics. Relative to commercial CB and pure BKF, the BKF fractions presented unique melting and crystallisation patterns. BKF presented olein and stearin fractions with separated melting and crystallisation behaviors. S-2 produced by further fractionation of S-1 had the highest SOS of 64.70%

compared with S-1 (55.83%) even pure BKF (40.71%). This result indicated the presence of high-melting symmetrical TAGs that increased the hardness of the fat and led to the formation of desirable thermal properties. The stearin fractions (i.e. S-1 and S-2) presented sharp and wide-ranging melting profiles that shifted to high temperatures. The polymorphic behavior of the stearin fractions was also not significantly different from that of CB because they possessed theβ-form which is suitable for chocolate manufacturing. Therefore, the stearin fractions are ideal for the CBI manufacturing of heat resistant confectionery products. The stearins can also be applied as SOS-rich fat resources for confectionery fat by blending or interesterification. Olein fractions with a low melting profile can be used with other vegetable fats and oils for producing cooking oils.

CRediT authorship contribution statement

M.R. Norazlina:Data curation, Formal analysis, Writing - original draft.M.H.A. Jahurul:Supervision, Conceptualization, Methodology, Supervision, Validation, Writing - original draft, Writing - review &

editing.M. Hasmadi:Funding acquisition, Writing - review & editing.

M.S. Sharifudin: Visualization, Investigation. M. Patricia: Project administration, Investigation. J.S. Lee: Software, Investigation, Validation. H.M.S. Amir: Resources, Investigation, Software. A.W.

Noorakmar:Software, Validation.I. Riman:Software, Validation.

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Declaration of competing interest None.

Acknowledgements

This research wasﬁnancially supported by the Centre of Research and Innovation, Universiti Malaysia Sabah (UMS) Malaysia, Research Grant scheme (Grant No.: SDN0061-2019).

Appendix A. Supplementary data

Supplementary data to this article can be found online athttps://

doi.org/10.1016/j.lwt.2020.109558.

References

deMan, J. M. (1994). X-Ray diﬀraction spectroscopy in the study of fat polymorphism.

Food Research International, 25, 471–476.

deMan, J. M., & deMan, L. (2001). Polymorphism and texture of fats. In N. Widlak, R.

Hartel, & S. Narine (Eds.).Crystallization and solidiﬁcation properties of lipids(pp. 225–

235). Champaign, IL: AOCS Press.

Afoakwa, E. O. (2014).Cocoa production and processing technology.CRC Press.

Al-sheraji, S. H., Ismail, A., Manap, M. Y., Mustafa, S., & Yusof, R. M. (2012). Viability and activity of biﬁdobacteria during refrigerated storage of yoghurt containingmangifera pajangﬁbrous polysaccharides.Journal of Food Science, 77(11), 624–630.

American Oil Chemists’Society (AOCS) (2009).Oﬃcials methods and recommended prac- tices of the American oil Chemists' Society(6th ed.). Campaign, IL, USA: AOCS Press.

Arishima, T., Sagi, N., Mori, H., & Sato, K. (1991). Polymorphism of POS. I. Occurrence and polymorphic transformation.Journal of American Oil Chemists Society, 68, 710–715.

Beckett, S. T. (2000).The science of chocolate.New York: Royal Society of Chemistry.

Beckett, S. T. (2008).The science of chocolate(2^nded.). Cambridge. UK: Royal Society of Chemistry.

Bergel, K. G. (2001). Palm oil. In F. D. Gunstone (Ed.).Structured and modiﬁed lipids(pp.

119–153). New York, NY: Marcel Dekker.

Bootello, M. A., Hartel, R. W., Garcés, R., Martínez-Force, E., & Salas, J. J. (2012).

Evaluation of high oleic-high stearic sunﬂower hard stearins for cocoa butter equivalent formulation.Food Chemistry, 134, 1409–1417.

Gujinkar, J. (2005).Mango kernel fat-an exotic fat international news on fats, oils and related materials: INFORM.ProQuest Central232.

Gunstone, F. D. (2011). Vegetable oils in food technology composition, properties and uses.Willy-blackwell(pp. 291–343). (2^nded.). CRC Press.

Hondoh, H., & Ueno, S. (2016). Polymorphism of edible fat crystals.Progress in Crystal Growth and Characterization of Materials, 62(2), 398–399.

Jahurul, M. H. A., Leykey, B., Sharifudin, M. S., Hasmadi, M., Zaidul, I. S. M., Jinap, S., et al. (2018b). Optimization of fat yield of bambangan (Mangifera pajang) kernel using response surface methodology and its antioxidant activities.Journal of Food Measurement and Characterization, 12(2), 1427–1438.

Jahurul, M. H. A., Ping, L. L., Sharifudin, M. S., Hasmadi, M., Mansoor, A. H., Lee, J. S., et al. (2019). Thermal properties, triglycerides and crystal morphology of bambangan (Mangifera pajang) kernel fat and palm stearin blends as cocoa butter alternatives.

LWT-Food and Technology, 107, 64–71.

Jahurul, M. H. A., Soon, Y., Shaarani Sharifudin, M., Hasmadi, M., Mansoor, A. H., Zaidul, I. S. M., et al. (2018a). Bambangan (mangifera pajang) kernel fat: A potential new source of cocoa butter alternative.International Journal of Food Science and Technology, 53(7), 1689–1697.

Jahurul, M. H. A., Zaidul, I. S. M., Norulaini, N. A. N., Sahena, F., Abedin, M. Z., Ghafoor, K., et al. (2014). Characterization of crystallization and melting proﬁles of blends of mango seed fat and palm oil mid-fraction as cocoa butter replacers using diﬀerential scanning calorimetry and pulse nuclear magnetic resonance.Food Research International, 55, 103–109.

Jin, J., Akoh, C. C., Jin, Q., & Wang, X. (2018a). Preparation of mango kernel fat stearin- based hard chocolate fats via physical blending and enzymatic interesteriﬁcation.

LWT-Food and Technology, 97, 308–316.

Jin, J., Jie, L., Zheng, L., Cheng, M., Xie, D., Jin, Q., et al. (2018b). Characteristics of palm mid-fractions produced from diﬀerent fractionation paths and their potential usages.

International Journal of Food Properties, 21(1), 58–69.

Jin, J., Mu, H., Wang, Y., Pembe, W., Liu, Y., Huang, J., et al. (2017c). Production of high- melting symmetrical monounsaturated triacylglycerol-rich fats from mango kernel fat by acetone fractionation.Journal of the American Oil Chemists’Society, 94(2), 201–213.

Jin, J., Wang, Y., Su, H., Warda, P., Xie, D., Liu, Y., et al. (2017b). Oxidative stabilities of mango kernel fat fractions produced by three-stage fractionation.International Journal of Food Properties, 20(11), 2817–2829.

Jin, J., Warda, P., Mu, H., Zhang, Y., Jie, L., Mao, J., et al. (2016). Characteristics of mango kernel fats extracted from 11 China-speciﬁc varieties and their typically fractionated fractions.JAOCS, Journal of the American Oil Chemists’Society, 93(8), 1115–1125.

Jin, J., Zheng, L., Mwinyi Pembe, W., Zhang, J., Xie, D., Wang, X., et al. (2017a).

Production of sn-1,3-distearoyl-2-oleoyl-glycerol-rich fats from mango kernel fat by selective fractionation using 2-methylpentane based isohexane.Food Chemistry, 234, 46–54.

Kang, K. K., Kim, I. H., Lee, C., & Kim, B. H. (2013). Selective enrichment of symmetric monounsaturated triacyglycerols from palm stearin by double solvent fractionation.

LWT- Food Science and Technology, 51, 242–252.

Kellens, M., Gibon, V., Hendrix, M., & De Greyt, W. (2007). Palm oil fractionation.

Fig. 4.Diﬀraction pattern for BKF and stearin fractions produced by two-stage acetone fractionation by XRD.

(8)

European Journal of Lipid Science and Technology, 109, 336–349.

Khairy, L. H., & Tajul, A. Y. (2016). Comparing the structural parameters of rambutan seed fat incorporated wholly and partially with cocoa butter.International Journal of Scientiﬁc and Engineering Research, 7, 921–928.

Koyano, T., Hachiya, I., & Sato, K. (1992). Phase behavior of mixed systems of SOS and OSO.Journal of Physical Chemistry, 96, 10514–10520.

Lipp, M., & Anklam, E. (1998). Review of cocoa butter and alternative fats for use in chocolate. Part A. Compositional data.Food Chemistry, 62, 73–97.

Loisel, C., Keller, G., Lecq, G., Bourgux, C., & Ollivon, M. (1998). Phase transition and polymorphism of cocoa-butter.Journal of the American Oil Chemists’Society, 75, 425–439.

Marangoni, A. G., & McGauley, S. E. (2003). Relationship between crystallization behavior and structure in cocoa butter.Crystal Growth & Design, 3(1), 95–108.

Minato, A., Ueno, S., Yano, J., Smith, K., Seto, H., Amemiya, Y., et al. (1997). Thermal and structural properties of sn-1,3-dipalmitoyl-2-oleoylglycerol and sn-1,3-dioleoyl- 2- palmitoylglycerol binary mixtures examined with synchrotron radiation X-Ray diﬀraction.Journal of the American Oil Chemists’Society, 74, 1213–1220.

de Oliveira, G. M., Badan Ribeiro, A. P., dos Santos, A. O., Cardoso, L. P., & Kieckbusch, T.

G. (2015). Hard fats as additives in palm oil and its relationships to crystallization process and polymorphism.Lebensmittel-Wissenschaft und -Technologie- Food Science and Technology, 63(2), 1163–1170.

Salas, J. J., Bootello, M. A., Martinz-Froce, E., & Garces, R. (2011). Production of stearate- rich butters by solvent fractionation of high stearic-high oleic sunﬂower oil.Food Chemistry, 124, 450–458.

Schenk, H., & Peschar, R. (2004). Understanding the structure of chocolate.Radiation

Physics and Chemistry, 71(3–4), 829–835.

Solís-Fuentes, J. A., del Rosario, M., Hernandez, M., del Carmen, M., & Durán-de-Bazúa, C. (2005). Determination of the predominant polymorphic from of mango (Mangifera indica) almond fat by diﬀerential scanning calorimetry and X-ray diﬀraction.

European Journal of Lipid Science and Technology, 107, 395–401.

Solís-Fuentes, J. A., & Durán-de-Bazúa, M. C. (2004). Mango seed uses: Thermal behavior of mango seed almond fat and its mixtures with cocoa butter.Bioresource Technology, 92, 71–78.

Solís-Fuentes, J. A., & Durán-de-Bazúa, M. C. (2011). Nuts and seeds in health and disease prevention. In V. R. Preedy, R. R. Watson, & V. B. Patel (Eds.).Mango (Mangifera indica L.) seed and its fats(pp. 741–748). Academic Press.

Sonwai, S., Kaphueakngam, P., & Flood, A. (2014). Blending of mango kernel fat and palm oil mid-fraction to obtain cocoa butter equivalent.Journal of Food Science &

Technology, 51(10), 2357–2369.

Timms, R. E. (2006). Fractionation of palm oil: Current status, future possibilities. In L.

Timothy (Ed.).Mounts award address presented at the AOCS world conference and ex- hibition on oilseed and vegetable oil utilization.

Tran, P. D., de Walle, D. V., Hinneh, M., Delbaere, C., Clercq, N. D., Tran, D. N., et al.

(2015). Controlling the stability of chocolates through the incorporation of soft and hard StOSt-rich fats.European Journal of Lipid Science and Technology, 117, 1700–1713.

Zzaman, W., Issara, U., Easa, A. M., & Yang, T. A. (2017). Exploration on the thermal behavior, solid fat content and hardness of rambutan fat extracted from rambutan seeds as cocoa butter replacer.International Food Research Journal, 24(6), 2408–2413.