Scholarly article on topic 'Using flaxseed oil to prepare therapeutical fat spreads'

Using flaxseed oil to prepare therapeutical fat spreads Academic research paper on "Agriculture, forestry, and fisheries"

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Abstract of research paper on Agriculture, forestry, and fisheries, author of scientific article — M.A. El-Waseif, H.A. Hashem, H.H. Abd EL-Dayem

Abstract The present study aims to evaluate the suitability of flaxseed oil (rich plant source of long chain omega-3 polyunsaturated fatty acid) as healthy oil in formulation of therapeutic fat spread. Eight fat spread samples containing 20%, 40%, 60%, 80% total blend fat were prepared. Total blend fat used in preparing different fat spread samples were prepared by blending flaxseed oil at various ratios with palm oil. However, other four fat spread samples were prepared as control sample using palm oil and soybean oil at different ratios. Each fat spread sample was analyzed for its moisture, fat, protein, ash and carbohydrate content as well as its sensory properties and microbiological characteristics. Total blend fat extracted from each fat spread sample was also analyzed for its physical and chemical properties, oxidative stability and fatty acid profile. The obtained results showed that all formulated fat spread samples were found to be in good microbiologically characteristics as they were free from contamination by different microorganism groups. The eight formulated fat spreads contained zero-trans fatty acids. The fatty acid C16:0 was the predominant saturated fatty acid, in all prepared formulated fat spread samples, while, C18:3 was the highest unsaturated one (the only omega-3 fatty acid in vegetable oils) followed by C18:1, the highest C18:3 level of different fat spreads formulated from flaxseed oil is due to the highest percent of C18:3 in such oil. Incorporation of flaxseed oil into fat spread samples had marked effect on their contents of such fatty acid. Inversely, all fat spread samples prepared from flaxseed oil showed less oxidative stability compared to control samples, another decreasing effect on resistance against the oxidative rancidity occurred as flaxseed oil% increased in the formulation. No significant differences were observed for sensory properties resulted from using flaxseed oil in fat spread formulations.

Academic research paper on topic "Using flaxseed oil to prepare therapeutical fat spreads"

Annals of Agricultural Science (2013) 58(1), 5-11

Faculty of Agriculture, Ain Shams University Annals of Agricultural Science

www.elsevier.com/locate/aoas

ORIGINAL ARTICLE

Using flaxseed oil to prepare therapeutical fat spreads

M.A. El-Waseif *, H.A. Hashem, H.H. Abd EL-Dayem

Department Food Science and Technology, Faculty of Agriculture, Al-Azhar University, Nasr City, Cairo, Egypt

Received 21 October 2012; accepted 5 November 2012 Available online 7 March 2013

KEYWORDS

Flaxseed oil; Fat spreads; Omega-3 fatty acid

Abstract The present study aims to evaluate the suitability of flaxseed oil (rich plant source of long chain omega-3 polyunsaturated fatty acid) as healthy oil in formulation of therapeutic fat spread. Eight fat spread samples containing 20%, 40%, 60%, 80% total blend fat were prepared. Total blend fat used in preparing different fat spread samples were prepared by blending flaxseed oil at various ratios with palm oil. However, other four fat spread samples were prepared as control sample using palm oil and soybean oil at different ratios. Each fat spread sample was analyzed for its moisture, fat, protein, ash and carbohydrate content as well as its sensory properties and microbiological characteristics. Total blend fat extracted from each fat spread sample was also analyzed for its physical and chemical properties, oxidative stability and fatty acid profile. The obtained results showed that all formulated fat spread samples were found to be in good microbiologically characteristics as they were free from contamination by different microorganism groups. The eight formulated fat spreads contained zero-trans fatty acids. The fatty acid C16:0 was the predominant saturated fatty acid, in all prepared formulated fat spread samples, while, C18:3 was the highest unsaturated one (the only omega-3 fatty acid in vegetable oils) followed by C18:1, the highest C18:3 level of different fat spreads formulated from flaxseed oil is due to the highest percent of C18:3 in such oil. Incorporation of flaxseed oil into fat spread samples had marked effect on their contents of such fatty acid. Inversely, all fat spread samples prepared from flaxseed oil showed less oxidative stability compared to control samples, another decreasing effect on resistance against the oxidative rancidity occurred as flaxseed oil% increased in the formulation. No significant differences were observed for sensory properties resulted from using flaxseed oil in fat spread formulations.

© 2013 Production and hosting by Elsevier B.V. on behalf of Faculty of Agriculture, Ain Shams

University.

* Corresponding author. Tel.: +20 01004951889. E-mail addresses: m_elwaseif@yahoo.com, melwaseif@gmail.com (M.A. El-Waseif).

Peer review under responsibility of Faculty of Agriculture, Ain-Shams University.

Introduction

Margarine (fat spread) is a water-in-oil emulsion with a high fat content. According to the US definition ''Margarine (or oleomargarine) is the food in plastic form or liquid emulsion containing no less than 80% fat'' (US-FDA, 1991). In Western Europe, yellow fat products other than butter are described as: ''Products in the form of a solid malleable emulsion, principally of the water-in-oil type, derived from solid and/or liquid

0570-1783 © 2013 Production and hosting by Elsevier B.V. on behalf of Faculty of Agriculture, Ain Shams University. http://dx.doi.org/10.1016/j.aoas.2013.01.002

vegetable and/or animal fats suitable for human consumption, with a milk fat content of not more than 3% of the fat content''. The category margarines is described as: ''The product obtained from vegetable and/or animal fats with a fat content of not less than 80% but less than 90% (EC, 1994). The product margarine includes table, bakery, and specialized puff pastry margarines and has been extended to various low calorie spreads which essentially contain much higher levels of water and lower levels of fat than those legally required in margarines (Laia et al., 2000).

Much of the above information about margarine (with over 80% fat) is equally applicable to many of the spreads with reduced fat content. The difference is relative rather than absolute, as long as the spreads are true water-in-oil emulsions. Generally, water-in-oil spreads vary in fat content between 20% and 80%; below 20% fat spreads are oil-in water emulsions. Products with a fat content between 41% and 62% are commonly referred to as reduced-fat spreads; whereas products with a fat content between 10% and 41% are called low-fat or light spreads (EC, 1994). Spreads formulated by vegetable oils are called ''fat spreads'' or ''non-dairy spreads'' (EC, 1994; CAC, 2003). Increased consumer awareness of diet and health has resulted in higher demand for functional foods. In the yellow spreads market, two major trends are emerging, i.e. enrichment with omega-3 and the reduction in Trans fatty acids (TFAs) (Timon, 2010).

Omega 3-fatty acids have a high nutritional status, its consumption has been reported to improve health by reducing the risk of cardiovascular disease, obesity, diabetes, inflammation, and several neurological diseases (Tou et al., 2011). But their use in food products is limited due to their susceptibility to li-pid oxidation, higher fish oil addition (as source of omega-3) in formulated fat spread resulted in increasingly fishy flavor and decreased sensory quality (Wee-Sim et al., 2007; Kolanowski et al., 2004). Flaxseed oil is a potentially vegetable important source of omega-3 as it is relatively stable to oxidation compared to fish oils (Morris, 2006).

Intake of high amounts of TFAs has been positively correlated with increased risk of coronary heart disease, inflammation, and cancer (Pande and Akoh, 2013). The major dietary sources of TFAs are products formulated with partially hydro-genated fats (margarines, shortenings, bakery products, and fast foods) (Wahle and James, 1993; Willet et al., 1993). Inter-esterification technique has been widely used to produce margarine and shortening fats which contain zero-trans-fat and improved spreadability and nutritional properties (Kim et al., 2008).

The present study was designed to through some light on the suitability of flaxseed oil (as healthy oil) in formulating edible table spreadable fats of good characteristics.

Materials and methods

Materials

Refined, bleached and deodorized palm oil and soybean oil were obtained from Arma Food Industries 10th of Ramadan City, Egypt. Flaxseeds (Linum usitatissimum L.) (Sakha 1) free from garden cress and weed seeds were obtained from Fiber Crops Research Section, Field Crops Research Institute, Agriculture Research Center, Cairo, Egypt. Other materials used as

additives including corn starch, sodium alginate and whey protein powder (3% total protein) (stabilizers), skim milk powder, soybean lecithin and glycerol monostearate (monoglyceride) (emulsifying agents); glycerol monostearate (antioxidant), potassium sorbate (preservative) and butter flavor were used in formulation of fat spreads.

Methods

Extraction of flaxseed oil

Flaxseeds were crushed by laboratory grinder, pressed using laboratory hydraulic press (Carver) under 10,000 Lb/inch2 for 1 h at room temperature (Ustun et al., 1990). The resultant oil was filtered through a fine cloth, kept in dark brown bottles and stored in deep freezer at —18 0C until analysis and formulation.

Preparation of fat spreads

Eight fat spread samples contains 20%, 40%, 60%, and 80% total fat were formulated, according to the method described by Cheng et al. (2008) and Lumor et al. (2010) with some modifications, their ingredients are shown in Table 1. Oils and additives soluble in fat (fat phase) (soy lecithin, glycerol mon-ostearate and ascorbyl palmitate) were mixed in stainless steel vessel, gently warmed at 40-50 0C with continuous steering until complete solublization and homogenecity were achieved (5-10min). Using another stainless steel vessel, aqueous phase (boiling water, corn starch, sodium alginate, skim milk powder, potassium sorbate and whey protein powder) were mixed using electric mixer at room temperature until complete solub-lization and homogenecity were achieved (1-2 min). Using ice bath, aqueous phase was added slowly into the fat phase and blended with a home mixer (at low speed) for 10 min followed by high speed for 5 min until complete homogenization occurred where the prepared spread had semi solid texture. Polypropylene containers (50 g capacity) were completely filled with the prepared fat spread, stored at refrigeration temperature (5-7 oc).

Chemical analysis of fat spreads

According to AOAC (2000), gross chemical composition of formulated fat spreads (moisture, crude protein, crude lipid and ash) was carried out. Total carbohydrate content was calculated by difference.

Physical and chemical properties of pure oils and oils extracted from fat spreads

Following methods described in AOAC (2000), AOCS (1983), and Sidwell et al. (1954), physical and chemical properties of oils and pure oil of formulated fat spread samples were determined. Physical properties including refractive index (at 25 0C and 40 0C for tested oils and spreadable fat samples, respectively), specific gravity, viscosity, melting and slip points and texture (for fat spread only). Acidity%, peroxide, iodine and TBA values represent the determined chemical properties.

Table 1 Ingredients of prepared fat spreads.

Ingredients % Fat spreads

20% Total fat 40% Total fat 60% Total fat 80% Total fat

SPB1 FPB1 SPB2 FPB2 SPB3 FPB3 SPB4 FPB4

Palm oil 6.00 6.00 20.00 20.00 30.00 30.00 40.00 40.00

Flaxseed oil - 12.00 - 18.50 - 29.50 - 39.00

Soybean oil 12.00 - 18.50 - 29.50 - 39.00 -

Glycerol monostearate 1.50 1.50 1.00 1.00 0.60 0.60 0.40 0.40

Soybean lecithin 0.60 0.60 0.50 0.50 0.40 0.40 0.20 0.20

Ascorbyl palmitate 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02

Butter flavour 0.03 0.03 0.03 0.03 0.02 0.02 0.02 0.02

Water 70.00 70.00 40.00 40.00 20.00 20.00 16.00 16.00

Potassium sorbate 0.20 0.20 0.20 0.20 0.10 0.10 0.10 0.10

Skim milk 2.00 2.00 4.40 4.40 5.00 5.00 1.00 1.00

Sodium alginate 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Whey protein 2.00 2.00 4.50 4.50 4.00 4.00 1.00 1.00

Starch 5.00 5.00 10.00 10.00 10.00 10.00 1.00 1.00

SPB1 = Soybean-Palm oils blend (20%) FPB1 = Flaxseed-Palm oils blend (20%) SPB2 = Soybean-Palm oils blend (40%) FPB2 = Flaxseed-Palm oils blend (40%) SPB3 = Soybean-Palm oils blend (60%) FPB3 = Flaxseed-Palm oils blend (60%) SPB4 = Soybean-Palm oils blend (80%) FPB4 = Flaxseed-Palm oils blend (80%).

Fatty acid profile

Fatty acid composition of studied oils and fat spread samples was determined using gas liquid chromatography technique. Methylation process was carried out using BF3 in methanol (20%) (AOAC, 1995).

Trans fatty acids

Trans fatty acids in the fat spread samples were detected by using Schimadzu FTIR 8101 PC Infra-red spectrophotometer according to Nicolova (1992).

Stability test (Rancimat induction period)

The Rancimat induction period measurements were carried out on the fresh oils and formulated fat spread samples. The induction period, as an index for oxidative stability was measured by an automated Rancimat (Metrohm Ud. CH-9100 Herisau, Switzeland, model 679), according to the method described by Tsaknis et al. (1999).

Microbiological analysis

Microbiological status of prepared fat spread samples (immediately after formulation) was assessed including total bacterial count using Plate Count Agar, incubation at 35-37 0C for 2448, mold and yeast count using Potato Dextrose Agar, incubation at 20-25 0C for 2-5 days and psychrophilic bacteria count using Plate Count Agar and incubation at 5-7 0C for 5-7 days (Downes and Ito, 2001; Wehr and Frank, 2004; FDA, 2005). Lipolytic bacteria count (using Tributyrin Agar and incubation at 5-7 0C for 10 days (International Dairy Federation standards ISO 6610, 6730; 1992) while, Coliform bacteria contamination was detected using presumptive test using Mac-Conkey broth and incubation at 35-37 0C for 24-48 h (Murray et al., 2007).

Sensory evaluation

According to Kolanowski and WeiXbrodt (2007), the eight tested fat spread samples were sensory evaluated after preparation by 10 panelists using a scale of 10 points. Evaluated properties include color, taste, odor, spreadability, texture, appearance and overall acceptability. Obtained results were statistically analyzed by one-way analysis of variance using SPSS 16.0 for windows was performed on all experimental data sets. Post-hoc multiple comparisons were carried out by Duncan analysis to determine significant differences between sample means at 5% level.

Results and discussion

Table 2 shows the gross chemical composition of the eight formulated fat spread samples. An inverse relation between moisture and fat contents was noted, their percentages ranged from about 14% to 70% and from about 21% to 97% for moisture and fat contents respectively. The same relation was found for ash content (0.34-6.14% on dry weight basis) and carbohydrate (2.89-25.11% on dry weight basis). There is no obvious trend for other determined major components when soybean oil was replaced by flaxseed oil in the formulation of any tested fat spread samples. These findings were found in general agreement with the results of Evers et al. (2000).

With regard to physical and chemical characteristics of tested oils; (Table 3), flaxseed oil showed the highest value of refractive index and iodine value (1.4770 and 200.97 respectively) compared to either palm oil or soybean oil. Wide variations were noticed for values of melting point of oils (—16, — 18 and 36 0C for soybean oil, flaxseed oil and palm oil, respectively); slip point (—14.40, —16.70 and 34 0C, respectively) and viscosity (800, 800 and 240,000 CPs, respectively). Tabulated results of the determined physical and chemical characteristics of tested vegetable oils agreed with those reported in the Egyptian Standard Specifications for palm oil

Table 2 Chemical composition of formulated fat spreads. Chemical composition (%) Fat spreads

20% Total fat 40% Total fat 60% Total fat 80% Total fat

SPB1 FPB1 SPB2 FPB2 SPB3 FPB3 SPB4 FPB4

Moisture 69.36 68.31 36.37 38.69 18.30 18.98 14.89 13.90

Fat 21.19 21.31 45.52 43.23 62.62 64.14 81.73 83.21

Protein 0.42 0.50 1.04 1.15 1.24 1.09 0.57 0.11

Ash 1.58 1.95 1.43 1.53 1.12 0.98 0.34 0.29

Carbohydrates 7.45 7.93 15.64 15.40 16.72 14.81 2.47 2.49

Table 3 Physical and chemical characteristics of pure oils and oils of formulated fat spreads.

Vegetable oils Fat spreads

Palm oil Soybean oil Flaxseed oil 20% Total fat 40% Total fat 60% Total fat 80% Total fat

SPB1 FPB1 SPB2 FPB2 SPB3 FPB3 SPB4 FPB4

Refractive index 1.4631 1.4713 1.4770 1.4749 1.4779 1.4715 1.4755 1.4710 1.4749 1.4710 1.4754

Specific gravity 25 °C 0.9024 0.9144 0.9105 - - - - - - - -

Melting point (°C) 36.00 -16.00 -18.00 31.50 31.50 33.00 33.00 33.50 33.50 34.50 34.50

Slip point (°C) 34.00 -14.40 -16.70 30.00 30.00 31.50 31.50 32.00 32.00 33.00 33.00

Texture firmness (N) - - - 1.460 1.260 9.800 9.460 14.160 14.030 14.960 14.630

Adhesiveness (Ns) - - - 1.431 3.010 6.485 7.245 9.868 9.659 13.516 14.189

Viscosity (CPs) 240000 800 800 43400 42300 45900 42200 58800 51900 62000 60000

Free fatty acid (as oleic acid%) 0.04 0.04 0.22 0.289 0.847 0.684 0.977 0.428 0.532 0.183 0.344

Peroxide value 0.54 0.89 0.78 2.699 2.374 4.325 1.879 2.095 1.842 0.394 0.732

TBA value 0.35 0.57 0.30 0.624 0.428 0.462 0.406 0.514 0.442 0.956 0.624

Iodine value 54.39 131.90 200.12 91.00 109.00 89.10 116.50 91.40 119.30 90.80 120.40

Saponification number 230.61 202.00 206.97 - - - - - - - -

Unsaponifiable matter (%) 0.65 0.86 1.23 - - - - - - - -

(No. 1520-2005), soybean oil (No. 49-6-2005) and flaxseed oil (No. 49-4-2005) that indicate the good quality of oils used in spread formulation.

When flaxseed oil was incorporated into formulation, refractive index and iodine values increased and this could be attributed to its high unsaturation degree as it exhibited the highest iodine value (200.12) compared to (54.39 and 131.90) for palm oil and soybean oil, respectively. While flax-seed oil had no effect on melting and slip points of formulated samples as they exerted similar values whether flaxseed oil was used or the sample was formulated without such oil (control).

The textural properties (firmness or hardness and adhesiveness) of formulated fat spread samples are given in Table 3. All eight fat spread samples were obviously different in terms of each attribute. As total fat% increases, hardness and adhesiveness values were also increased markedly. So, fat spread samples of 80% total fat had the highest values and will therefore be more difficult to spread compared to the other treatments. Fat spread samples containing 20% total fat had lowest hardness value probably because they were formulated with less fat (Lumor et al., 2010). The same trend was noted for adhesiveness property as the more adhesive a spread is, the more likely it will stick to utensil such as spreading knife (Lumor et al., 2010). Using flaxseed oil (instead of soybean oil) in fat spread formulation showed little increasing effect on values of both texture parameters (firmness and adhesiveness).

As total fat% of formulated fat spreads was increased, parallel increase of viscosity values was found, therefore, samples contained the highest fat content (80%) showed the highest viscosity values. This finding coincides with viscosity values

of used oils as% of palm oil (had very high viscosity value) was elevated as total fat content was increased in the fat spreads. Results in Table 3 were found in general agreement of those reported by Berger (1996), Nikolova et al. (2007), Alexa et al. (2010), Shin et al. (2010), and Sutivisedsak et al. (2011).

As shown in Table 4, flaxseed oil had the highest total unsaturated fatty acids TUFAs content (89.29%) followed by soybean oil (84.26%), while palm oil contained comparable amounts of saturated TSFAs and unsaturated fatty acids (50.20% and 49.80%, respectively). The two fatty acids C16:0 and C18:0 were the highest saturated fatty acids in the three studied oils as there percentages were reached to 43.89%, 4.44%; 10.45%, 3.56%; 5.71% and 4.84% in palm, soybean and flaxseed oils, respectively. For unsaturated fatty acids, the highest value were found to be 39.21% and 10.03% for C18:1 and C18:2, respectively in palm oil; 50.62% and 28.13% for C18:2 and C18:1, respectively in soybean oil; 59.02%, 15.11% and 14.99% for C18:3, C18:2 and C18:1, respectively in flaxseed oil.

Flaxseed oil exerted it superiority among the three used oils concerning C18:3 fatty acid (the only omega-3 fatty acid in vegetable oils) content, it composed about 66.10% in of TUFAs compared to 6.04% and 0.34% in soybean oil and palm oil, respectively.

Formulated fat spreads of different total fat percentage had relatively high TUFAs content (65.53-71.20%). The fatty acid C16:0 showed the highest value among saturated fatty acid, while the unsaturated fatty acids C18:3, C18:1 exhibited the highest values in fat spreads formulated using flaxseed oil,

Table 4 Fatty acid profile of pure oils and oils of formulated fat spreads.

Vegetable oils Fat spreads

Palm oil Soybean oil Flaxseed oil 20% Total fat 40% Total fat 60% Total fat 80% Total fat

SPB1 FPB1 SPB2 FPB2 SPB3 FPB3 SPB4 FPB4

C12:0 0.19 ND ND 0.08 0.07 0.09 0.10 0.07 0.10 0.10 0.10

C14:0 1.09 ND ND 0.50 0.43 0.60 0.61 0.56 0.61 0.60 0.60

C16:0 43.89 10.45 5.71 26.36 21.35 28.27 27.41 27.29 26.61 27.81 26.62

C16:1 0.22 0.12 0.07 0.03 0.11 0.20 0.13 0.26 0.13 0.23 0.13

C17:0 0.10 0.85 ND 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08

C17:1 0.02 0.06 ND 0.03 0.02 0.03 0.02 0.03 0.02 0.03 0.02

C18:0 4.44 3.56 4.84 5.88 6.44 4.60 5.21 4.24 4.38 4.10 4.78

C18:1 39.21 28.13 14.99 29.94 22.65 33.22 27.88 33.74 27.25 33.34 27.55

C18:2 10.03 50.62 15.11 33.83 12.96 29.79 12.25 30.63 12.32 30.56 12.25

C18:3 0.17 5.09 59.02 2.52 35.38 2.13 25.74 2.25 27.45 2.20 27.30

C20:0 0.37 0.39 0.16 0.33 0.21 0.43 0.24 0.40 0.23 0.43 0.23

C20:1 0.15 0.24 0.10 0.18 0.08 0.30 0.09 0.23 0.09 0.28 0.09

C22:0 0.12 0.49 ND 0.24 0.22 0.26 0.24 0.22 0.23 0.24 0.25

TUFAs 49.80 84.26 89.29 66.53 71.20 65.67 66.11 67.14 67.76 66.64 67.34

TSFAs 50.20 15.74 10.71 33.47 28.80 34.33 33.89 32.86 32.24 33.36 32.66

Trans fatty acid - - - 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Table 5 The oxidative stability of pure oils and oils of formulated fat spreads.

Oxidative stability at 100 0C Vegetable oils Fat spreads

Palm Soybean Flaxseed 20% Total fat 40% Total fat 60% Total fat 80% Total fat

°U SPB1 FPB1 SPB2 FPB2 SPB3 FPB3 SPB4 FPB4

Induction period in h Induction period in months (Validity period) 76.00 36.00 6.00 101.20 32.78 42.00 19.90 3.35 56.10 22.40 85.36 47.32 28.68 18.17 65.58 35.29 23.54 16.32 56.76 31.46 18.22 13.05

Table 6 Sensory evaluation of formulated fat spreads.

Fat spreads

20% Total fat

40% Total fat

60% Total fat

80% Total fat

Color Taste Odor

Spreadability

Texture

Appearance

5.40 ± 0.52c 5.70 ± 0.48b 6.00 ± 0.67c

5.90 ± 0.57b 5.90 ± 0.61b 6.30 ± 0.67c

6.60 ± 0.46b 7.05 ± 0.16b 6.15 ± 0.85b 6.70 ± 0.63b 7.00 ± 0.82b 7.40 ± 0.84b 8.00 ± 0.67b

7.60 ± 0.46b 7.50 ± 0.71b 7.70 ± 0.63b 7.85 ± 0.58b

7.30 ± 0.48b 7.50 ± 0.85b 7.40 ± 0.52b 7.20 ± 0.35b

6.70 ± 0.67b 7.30 ± 0.71b 8.20 ± 0.48a

Overall acceptability 6.60 ± 0.84b 6.35 ± 0.58b 6.70 ± 0.67b 6.90 ± 0.74b

7.60 ± 0.66a 7.90 ± 0.74a 8.10 ± 0.52a 8.30 ± 0.54a 8.40 ± 0.52b 8.70 ± 0.48a 8.20 ± 0.35a

8.45 ± 0.55a 8.20 ± 0.63a 8.50 ± 0.47a 8.20 ± 0.79a 8.50 ± 0.53a 8.80 ± 0.42a 8.50 ± 0.47a

7.90 ± 0.70a 8.60 ± 0.46a 8.70 ± 0.42a 8.60 ± 0.52a 9.15 ± 0.24a 8.80 ± 0.35a 8.80 ± 0.35a

8.65 ± 0.47a 8.50 ± 0.47a 8.30 ± 0.54a 8.80 ± 0.42a 9.00 ± 0.00a 8.90 ± 0.21a 8.60 ± 0.46a

(M ± S.D) = Mean ± Std. Deviation. ** High significant (P < 0.01).

a,b,c Significant difference between the same parameter in same the row.

while C18:2, C18:1 has the highest value in control samples (without flaxseed oil). Using flaxseed oil in formulation resulted in fat spreads of relative higher TUFAs content compared to control treatments. Also, incorporation of flaxseed oil into fat spreads during formulation markedly increase their contents of omega-3 fatty acid (C18:3), its percentage reached to (38.93-49.69% of total unsaturated content), while fat spreads free of flaxseed oil showed corresponding values of (3.24-3.79%). Results in Table 4 revealed that all formulated fat spreads either control or those formulated with flaxseed oil were completely free of TFAs therefore fat spreads with zero trans fat content will be beneficial, this finding agreed

with those reported by Wee-Sim et al. (2007), Jin et al. (2008), Shin et al. (2010), Adhikari et al. (2010), Liu et al. (2010), Sutivisedsak et al. (2011), and Danthine (2012).

Table 5 shows that palm oil had marked highest oxidative stability among the tested oils, while, flaxseed oil had the least corresponding stability. This may be attributed to unsaturation degree as Table 4 showed that TUSFs in palm oil and flax-seed oil were 49.80% and 89.29%, respectively. These finding coincides with Anwar et al. (2003) who cited that higher content of SFA lead to high oxidative stability and resistance against the oxidative rancidity. Consequently, incorporation of flaxseed oil into fat spreads resulted in products of less oxi-

dative stability. Increasing amount of such oil in formulated fat spreads had another decreasing effect on oxidative stability of the product.

Sensory evaluation is an important tool that links product attributes with consumer preferences. Results in Table 6 declares that as fat% increased in fat spreads formulation mean scores of all evaluated properties are significantly (P < 0.01) increased. Kok et al. (1999) and Kolanowski and WeiXbrodt (2007) concluded comparable observations. In addition, no significant differences were noted for most properties mean scores as a result of using flaxseed oil in the process of fat spreads formulation. These finding was observed for all investigated fat spread samples with different contents of total fat.

As mentioned earlier, microbiological status of formulated fat spreads immediately after formulation was assessed. Prepared fat spreads of different oils and / or total fat% exerted their freedom of contamination with aerobic bacteria, mold and yeast, psychrophilic, lipolytic and coliform bacteria. These could be taken as indicator for good hygienic precautions followed during formulation process.

In conclusion, using pure flaxseed oil in fat spread formulation can be considered as promise trend in the field of therapeutical fat spreads. There spreads characterizes by relative high TUFAs content, especially the healthy fatty acid (ome-ga-3, C18:3) with good sensory properties. On the other hand, incorporation of flaxseed oil in fat spread formulation lead to a product of relatively low oxidative stability.

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