Characterization and application of lecithin powders from sunflower and peanut to enhance oil stability in peanut butter

Abstract

This study aimed to evaluate the effect of adding sunflower and peanut lecithin powders on reducing oil separation in peanut butter in order to enhance its quality. GC–MS analysis revealed that the higher phospholipid content in sunflower lecithin (30.49 %) than in peanut lecithin (16.98 %). Sunflower lecithin also contained higher levels of linoleic (10.53 %) and stearic acids (0.93 %) compared to peanut lecithin (2.09 % and 0.45 %, respectively). Peanut seeds were processed in to butter, and lecithin powders were added at 1 %, 1.5 %, and 2 % concentrations. Peanut butter with 2 % sunflower lecithin showed the lowest increase in peroxide value, free fatty acids, and oil separation, while the control sample exhibited the highest values. Sensory evaluation indicated that 2 % sunflower lecithin provided the best appearance, texture, flavor, and overall acceptability. The findings suggest that sunflower lecithin is a superior emulsifier for peanut butter, extending its shelf life compared to peanut lecithin.

Highlights

• •Comparing sunflower vs. peanut lecithin as natural stabilizers in peanut butter.
• •Sunflower lecithin yielded a higher phospholipid content (30.49 %).
• •Sunflower lecithin was more effective in reducing oil separation, peroxide value.
• •Sunflower lecithin enhanced the sensory properties and shelf-life of peanut butter.

1. Introduction

Peanut (Arachis hypogaea), locally known as “Fool Sudani” in Sudan, is a significant crop in the country's agricultural economy and foreign trade (Issaoui & Delgado, 2019). Primarily cultivated as a rain-fed crop, peanut is grown extensively for its oil, with an estimated 7.2 million hectares dedicated to its production in the traditional sector. Of this, approximately 129,382 hectares are occupied by peanut farms, yielding around 278,232 tons of seeds annually (MFAS, 2003). Peanut seeds are utilized either directly as food or processed into oil and high-protein meal, with nearly two-thirds of global production being crushed for oil extraction (Deshpande, 2000). Among its processed forms, peanut butter is a highly nutritious food product made from roasted, shelled, and ground peanut seeds. It typically consists of peanut paste, stabilizers, and optional additives such as sweeteners, salt, and emulsifiers.

A major challenge in peanut butter production is oil separation, which often indicates rancidity due to the exposure of free oil to air and light. Various stabilizers have been explored to mitigate this issue (Mohd Rozalli et al., 2016). Lecithin, a complex mixture of polar lipids derived from crude vegetable oils through water-degumming, has been studied for its role in peanut butter. While Gordon (1947) noted that lecithin improves spreadability and acts as an antioxidant, it can exacerbate oil separation. Lecithin primarily comprises phospholipids, along with minor components such as steroid derivatives, glycolipids, and pigments (Osman-Bashir & Elhussein, 2017). Sunflower lecithin, obtained through water-degumming of crude sunflower oil, exhibits mild flavor and emulsifying properties comparable to soybean lecithin (Shahidi, 2005). Similarly, peanut lecithin has demonstrated synergistic effects with tocopherols in delaying lipid oxidation, with deoiled lecithin offering enhanced functionality due to its higher polarity (Barouh et al., 2022).

The shelf life of peanut butter and related products is often limited by rancidity caused by the oxidation of unsaturated fatty acids (Nepote et al., 2006; Sheng & Wang, 2021). Eskin & Robinson, 2000 investigated the oxidative stability of peanut butter formulations, finding that additives like casein and lecithin delayed rancidity due to the presence of phosphoric acid groups in lecithin, which enhance the activity of phenolic antioxidants. Recent studies have further highlighted the role of natural antioxidants and emulsifiers in improving the stability of peanut-based products (Yu et al., 2022).

This study aims to evaluate the effect of sunflower and peanut lecithin powder as emulsifer to prevent separation of oil in peanut butter, thereby maintaining its quality characteristics (general appearance of the product and its stability against oxidation) during storage. By addressing this issue, the research seeks to enhance the shelf life and consumer acceptability of peanut butter products.

2. Material and methods

2.1. Materials

Crude peanut and sunflower oils were purchased from Alruda factory for edible oil.

2.2. Extraction of lecithin from crude sunflower and peanut oils

Lecithin extraction was performed following the method described by Eshratabadi et al. (2008) with minor modifications. The process involved acid degumming of crude oil, where phospholipids were hydrated by mixing the oil with a small volume of water, rendering them insoluble in the oil. Approximately 20 g ± 0.1 mg of oil was placed in a glass beaker, and 3 mL of a 0.5 % citric acid solution was added. The mixture was stirred and heated at 70 °C for 30 min. The oil and water phases were then separated by centrifugation at 1500 ×g for 30 min resulting in the formation of a gum or crude lecithin layer at the bottom. The two layers were transferred to a separator funnel to isolate the crude lecithin from the oil layer. The lower layer (crude lecithin) was collected in an aluminum dish and dried in an oven at 82 °C under vacuum (50 mmHg) for 3–5 h to obtain crude lecithin. The crude lecithin was stored in a plastic container and refrigerated at 3 °C until further purification.

2.3. Purification of crude sunflower and peanut (phospholipids

Purification of crude lecithin was conducted following the method outlined by Nasir et al. (2007). The process aimed to remove neutral oil from crude lecithin. Dried crude lecithin was mixed with acetone at a ratio of 1:6 (w/v), and the mixture was stirred and cooled to 5 °C in a water bath for 1 h. The solvent was separated from the lecithin by decantation, and this treatment was repeated until the solvent became colorless. The precipitated lecithin was then dried in a water bath at 80 °C until all acetone evaporated, yielding purified lecithin powder.

2.4. Identification of the components of deoiled sunflower and peanut lecithin powders

Quantitative estimation of lecithin was carried out by Gas Chromatography Mass Spectroscopy (GC–MS) according to the method described by Sreedevi et al. (2012)).

2.5. Preparation of peanut butter with different lecithin concentrations

Peanut butter was prepared from peanut seeds following the method described by Dhamsaniya et al. (2012), with modifications for laboratory-scale production. A total of 5 kg of peanuts were blanched, cooled, de-skinned, and sorted to remove discolored or damaged kernels. The peanuts were roasted at 140 °C for a specified duration. After roasting, the peanuts were ground using a colloid mill to achieve a fine texture. Emulsifiers (sunflower and peanut lecithin powders) were added to the mixture at three concentrations (1 %, 1.5 %, and 2 % w/w) and manually blended using a wooden spoon for approximately five minutes. The ground peanut butter was portioned into seven plastic containers, with each container receiving a different concentration of lecithin powder. A control sample without any stabilizer was also prepared. All containers were tightly sealed and stored at room temperature for six months. During storage, samples were withdrawn monthly for analysis and stability assessment. The lecithin concentrations were added as follows: 1 g, 1.5 g, and 2 g of lecithin powder per 100 g of peanut butter product.

2.6. Analysis of Peanut seeds and Peanut butter

The peanut butter samples were analyzed to assess their quality and stability against oxidation. The chemical composition of both peanut seeds and peanut butter, including moisture content, fat content, ash content, protein content, and fiber content, was determined according to the standard methods outlined by Agroindustriais (2013).

2.7. Total carbohydrate content

Total carbohydrate content was estimated by the difference method. The sum of ash, moisture, crude protein, and oil contents was subtracted from 100 to determine the carbohydrate percentage (Pearson, 1976).

2.8. Energy value

The energy value of each sample was calculated using the Atwater factors, where 4 kcal/g, 9 kcal/g, and 4 kcal/g were assigned to protein, fat, and carbohydrate content, respectively (Pattee et al., 2000).

2.9. Peroxide value (PV)

The peroxide value (PV) of the oil was determined to assess the extent of primary lipid oxidation. This was carried out according to the standard method described by Agroindustriais (2013).

2.10. Free fatty acids (FFA)

Free fatty acid content was calculated by dividing the acid value by two, as described by Agroindustriais (2013). This parameter is an indicator of hydrolytic rancidity in peanut butter.

2.11. Oil separation test

The oil separation test was conducted to evaluate the stability of peanut butter during storage. This was performed according to the method described by Ereifej et al. (2005), which measures the amount of oil that separates from the peanut butter matrix over time.

2.12. Sensory evaluation

A semi-trained panel of 70 participants (both male and female, aged 20–55 years) evaluated the peanut butter using a 9-point hedonic scale (1 = “dislike very much” to 9 = “like very much”). Selection criteria included being regular consumers of peanut butter (consumption at least once per month), absence of peanut allergy, and no reported sensory impairments (taste or smell). The panelists were trained and calibrated in sessions. Training involved familiarization with the sensory attributes to be evaluated appearance, texture, flavor, and overall acceptability with clear operational definitions provided for each attribute. The methodology was adapted from Meilgaard et al. (1999). All evaluations were conducted under standardized white lighting at a controlled room temperature of 25 °C.

2.13. Statistical analysis

Each sample was analyzed in triplicate, and the mean values were used for statistical analysis. Data were analyzed using the Completely Randomized Design (CRD) model of analysis of variance (ANOVA) in SAS statistical software. Treatment means were compared according to the procedures described by Montgomery and Douglas (2001).

3. Results and discussion

The percentage yield of lecithin extracted from sunflower and peanut oils is presented in Fig. 1. The results revealed a significant difference (p ≤ 0.05) in lecithin yield between the two oil types. Sunflower oil exhibited a significantly higher lecithin yield (3.17 %) compared to peanut oil (1.5 %). These findings are consistent with van Nieuwenhuyzen & Tomás (2008), who reported similar lecithin yields: 3.5 % for sunflower oil and 1.3 % for peanut oil.

Fig. 1.

Lecithin content separated from crude peanut and sunflower oils.

The higher lecithin yield from sunflower oil could be attributed to its higher phospholipid content, which is more readily extracted during the degumming process. Sunflower oil is known to contain a greater proportion of hydratable phospholipids, making it more suitable for lecithin extraction compared to peanut oil (Shahidi, 2005). In contrast, the lower yield from peanut oil may be due to its lower phospholipid content and the presence of non-hydratable phospholipids, which are less efficiently extracted using conventional degumming methods (Yu et al., 2022).

These results highlight the potential of sunflower oil as a superior source of lecithin for industrial applications, particularly in food products requiring effective emulsification and stabilization. The findings also underscore the importance of selecting appropriate raw materials for lecithin production to optimize yield and functionality.

3.1. Physicochemical properties of peanut and sunflower lecithin powders

The physicochemical properties of peanut and sunflower lecithin powders are presented in Table 1. Significant differences (p ≤ 0.05) were observed in acetone-insoluble phosphatides, moisture content, peroxide value, and acid value between the two lecithin samples.

Table 1.

Physicochemical identification tests of lecithin powder separated from peanut and sunflower oils.

Test	Type of deoiled lecithin powder		P-value
	Peanut lecithin powder	Sunflower lecithin powder
Acetone insoluble phosphatides % (purity)	61.74 ± 0.81	70.14 ± 0.90	0.00**
Moisture content (%)	1.19 ± 0.04	1.32 ± 0.03	0.0183*
Peroxide value (Meq O2/kg oil)	3.60 ± 0.29	1.50 ± 0.04	0.0001**
Acid value (mg KOH/g oil)	17.06 ± 0.17	18.24 ± 0.33	0.00**

Values are expressed as mean ± SD of three independent experiments (n = 3). Differences between means considered significant at *p < 0.05, **p < 0.01.

Sunflower lecithin powder exhibited a significantly higher acetone-insoluble phosphatide content (70.14 %) compared to peanut lecithin powder (67.86 %). This indicates a greater concentration of phospholipids in sunflower lecithin, which is consistent with its higher yield during extraction and its superior emulsifying properties (Shahidi, 2005). Moisture content was also higher in sunflower lecithin powder (1.32 %) than in peanut lecithin powder (1.19 %), suggesting differences in hygroscopicity and water-binding capacity between the two samples.

In terms of oxidative stability, peanut lecithin powder had a significantly higher peroxide value (3.6 meq O₂/kg oil) compared to sunflower lecithin powder (1.5 meq O₂/kg oil). This lower peroxide value in sunflower lecithin is indicative of enhanced resistance to primary oxidation. The mechanistic link for this improved stability can be attributed to its specific phospholipid composition and fatty acid profile. Phospholipids like phosphatidylcholine and phosphatidylethanolamine can act as metal chelators, binding pro-oxidant metal ions (e.g., Fe²⁺, Cu²⁺) and thereby inhibiting the metal-catalyzed initiation of lipid oxidation (Laguerre et al., 2007). Furthermore, the fatty acid profile of sunflower lecithin, which contained a lower total proportion of oxidation-prone polyunsaturated fatty acids (14.93 %) compared to peanut lecithin (20.5 %), contributes directly to its superior oxidative stability. The synergistic effect of a less susceptible fatty acid profile and the potential antioxidant properties of the phospholipid headgroups effectively retards the formation of primary oxidation products (hydroperoxides), as evidenced by the lower peroxide value (Yu et al., 2022).

However, sunflower lecithin showed a higher acid value (18.24 mg KOH/g oil) than peanut lecithin (17.06 mg KOH/g oil), indicating a greater concentration of free fatty acids. This may be attributed to differences in processing conditions or the presence of more hydrolyzed lipids in sunflower lecithin (Frank, 2002).

All measured parameters, including acetone-insoluble phosphatides, moisture content, peroxide value, and acid value, were within the limits specified by the Indian Standard Specification for lecithin powder (IS 5055: 1996). This confirms that both peanut and sunflower lecithin powders meet the quality standards required for emulsifers.

The higher acetone-insoluble phosphatide content in sunflower lecithin powder aligns with its superior emulsifying properties, as phospholipids are the primary functional components of lecithin (Shahidi, 2005). The lower peroxide value of sunflower lecithin suggests better oxidative stability, which is advantageous for extending the shelf life of products containing lecithin (Yu et al., 2022). However, the higher acid value in sunflower lecithin may indicate a need for improved refining processes to reduce free fatty acid content and enhance quality.

These findings highlight the importance of selecting appropriate sources of lecithin based on specific application requirements. Sunflower lecithin, with its higher phospholipid content and oxidative stability, may be more suitable for applications requiring strong emulsification and extended shelf life. In contrast, peanut lecithin, with its lower acid value, may be preferred for applications where free fatty acid content is a critical factor.

3.2. Fatty acids and phospholipids content of lecithin powder

The fatty acid and phospholipid composition of lecithin powder extracted from crude peanut and sunflower oils is presented in Table 2. Significant differences (p ≤ 0.05) were observed in both fatty acid and phospholipid content between the two lecithin samples. Sunflower lecithin powder exhibited a significantly higher phospholipid content (30.49 %) compared to peanut lecithin powder (16.98 %). These findings are consistent with those reported by Hayes (2004), who also noted higher phospholipid levels in sunflower lecithin. Sunflower lecithin also contained higher levels of linoleic acid (10.53 %), palmitic acid (11.05 %), and stearic acid (0.93 %). In contrast, peanut lecithin powder had a significantly higher oleic acid content (18.41 %) compared to sunflower lecithin powder (4.4 %). Sunflower lecithin demonstrated superior phospholipid content, which is critical for its emulsifying and stabilizing properties in food applications (Shahidi, 2005).

Table 2.

Compounds identified by GC MS of lecithin powder separated from peanut oil and sunflower oil.

Compound (%)	Type of lecithin powder samples		P-value
	Peanut lecithin powder	Sunflower lecithin powder
Phospholipids (lecithin)	16.98 ± 0.03	30.49 ± 0.26	0.00**
Oleic acid	18.41 ± 0.22	4.40 ± 0.11	0.002**
Linoleic acid	2.09 ± 0.18	10.53 ± 0.17	0.032*
Palmitic acid	4.11 ± 0.23	11.05c ± 0.28	0.015**
Linolenic acid	ND	ND	–
Stearic acid	0.45 ± 0.03	0.93 ± 0.01	0.048*
Unsaturated fatty acids	20.50 ± 0.17	14.93 ± 0.17	0.00**
Saturated fatty acids	4.56 ± 0.12	11.98 ± 0.25	0.0003**
Other fatty acids and compounds	57.96 ± 0.44	42.60 ± 0.34	0.00**

Values are expressed as mean ± SD of three independent experiments (n = 3). Differences between means considered significant at *p < 0.05, **p < 0.01.

The observed differences may be attributed to variations in the purification process of crude lecithin, which can reduce neutral lipids while increasing the percentage of phospholipids in the final powder (Eiri, 2004; Vikbjerg et al., 2006).

The significantly higher phospholipid content in sunflower lecithin is the primary factor behind its superior emulsifying capacity and its effectiveness in suppressing oil separation. Phospholipids are amphiphilic molecules that form stable interfacial films at oil-water interfaces, reducing surface tension and preventing droplet coalescence. The higher concentration of these surface-active agents in sunflower lecithin allows for the formation of a more robust and continuous film around oil droplets within the peanut butter matrix, thereby more effectively immobilizing the oil phase and preventing its migration and separation during storage compared to peanut lecithin.

3.3. Chemical composition of Peanut seeds and Peanut butter

The chemical composition of peanut seeds and peanut butter is presented in Table 3. Significant differences (p ≤ 0.05) were observed in moisture, ash, fat, crude protein, crude fiber, carbohydrate, and energy content between peanut seeds and peanut butter.

Table 3.

Chemical composition of peanut seeds and peanut butter.

Parameter	Peanut seeds	Peanut butter	P-value
Moisture content (%)	2.94 ± 0.10	1.29 ± 0.13	0.0001**
Ash content (%)	3.29 ± 0.07	2.03 ± 0.05	0.00**
Fat content (%)	51.51 ± 1.09	53.79 ± 1.93	0.0149*
Crude protein (%)	18.57 ± 0.02	23.38 ± 0.14	0.00**
Crude fiber (%)	2.46 ± 0.12	1.97 ± 0.14	0.0099**
Carbohydrates (%)	23.72 ± 0.92	19.17 ± 1.84	0.0185*
Energy value (kcal/kg)	6326.37 ± 59.54	6647.47 ± 187.71	0.0003**

Values are expressed as mean ± SD of three independent experiments (n = 3). Differences between means considered significant at *p < 0.05, **p < 0.01.

The results revealed that the moisture, ash, fiber, and carbohydrate content decreased significantly in peanut butter compared to peanut seeds. Specifically, moisture content decreased from 2.94 % to 1.29 %, ash content from 3.29 % to 2.03 %, fiber content from 2.46 % to 1.97 %, and carbohydrate content from 23.72 % to 19.17 %. Conversely, fat, protein, and energy content increased significantly in peanut butter. Fat content from 51.51 % to 53.79 %, protein content from 18.57 % to 23.38 %, and energy value from 6326.37 to 6647.46 kcal/kg.

The moisture, fat, and protein content of peanut butter were within the ranges reported by McWatters and Young (1978). However, the moisture content of peanut seeds (2.94 %) was lower than the range reported by Woodroof (1983).

These compositional changes are a direct result of the processing steps involved in peanut butter production. During roasting and subsequent de-skinning, the outer seed coat (testa) which is rich in fiber, minerals (ash), and carbohydrates is largely removed. This removal accounts for the significant decrease in these components. The grinding process ruptures the oil-bearing cells, releasing oil and leading to an apparent concentration of fat and protein as the less dense, fibrous materials are eliminated. The reduction in moisture content is primarily due to the heat applied during roasting and cooling. Thus, the final composition of peanut butter is characterized by a concentration of the core lipid and protein constituents from the cotyledons and a reduction of components associated with the seed coat and moisture.

These findings highlight the importance of optimizing processing conditions to maintain the nutritional quality of peanut butter while minimizing undesirable changes in its chemical composition.

3.4. Peroxide value of Peanut butter during storage

Fig. 2 demonstrates that the addition of 1.5 % and 2 % peanut lecithin powder, as well as 2 % sunflower lecithin powder, effectively maintained the peroxide value (PV) of peanut butter oil within acceptable limits for up to four months of storage. The peroxide values remained below the threshold specified by the Codex Standard for Vegetable Oils (CODEX STAN 19–1981), which states that the PV of crude oil should not exceed 15 meq O₂/kg oil.

Fig. 2.

Effect of addition different types and levels of lecithin powder and storage periods on peroxide value (Meq. O2/kg oil) of peanut butter (P₁B) at room temperature.

PB = peanut butter; PBPL(1.0) = peanut butter treated with 1.0 % peanut lecithin; PBPL(1.5) = peanut butter treated with 1.5 % peanut lecithin; PBPL(2.0) peanut butter treated with 2.0 % peanut lecithin; PBSL(1.0) peanut butter treated with 1.0 % sunflower lecithin; PBSL(1.5) = peanut butter treated with 1.5 % sunflower lecithin; PBSL(2.0) = peanut butter treated with 2.0 % sunflower lecithin.

These findings align with Elshimi (1992). This effect is attributed to the presence of phosphoric acid groups in phospholipids, which enhance the activity of phenolic antioxidants and chelate pro-oxidant metal ions, thereby improving oxidative stability. Sunflower lecithin, with its higher phospholipid content (Table 2), demonstrated superior performance, providing a greater concentration of these protective compounds.

The ability of lecithin to maintain low peroxide values in peanut butter oil during storage highlights its role as an effective antioxidant and stabilizer. The phosphoric acid groups in lecithin contribute to its antioxidant properties by chelating metal ions and scavenging free radicals, thereby slowing lipid oxidation (Yu et al., 2022). Sunflower lecithin, in particular, demonstrated superior performance at a 2 % concentration, likely due to its higher phospholipid content, which enhances its emulsifying and antioxidant capabilities (Shahidi, 2005).

These results underscore the importance of incorporating lecithin, particularly sunflower lecithin, into peanut butter formulations to extend shelf life and maintain product quality. The findings also support the use of lecithin as a natural alternative to synthetic antioxidants in food products.

3.5. Free fatty acid content of Peanut butter

Fig. 3 indicates that there were no significant differences (p > 0.05) in free fatty acid (FFA) content between the control sample and peanut butter treated with different types and concentrations of lecithin powder. The FFA content of all samples, including the control, remained within the limits specified by the Indian Standard Specification for peanut butter, which states that the FFA content should not exceed 2 %.

Fig. 3.

Effect of addition different types and levels of lecithin powder and storage periods on free fatty acids (%) of peanut butter (P₂B) at room temperature.

The absence of significant differences in FFA content among the control and treated peanut butter samples suggests that the addition of lecithin powder, regardless of type or concentration, did not adversely affect the hydrolytic stability of the product. This is consistent with the role of lecithin as an emulsifier and stabilizer, which helps maintain the integrity of the lipid matrix and prevents the release of free fatty acids (Shahidi, 2005). The compliance of all samples with the Indian Standard Specification (IS 5055: 1996) further confirms the suitability of lecithin as an additive for improving the quality and shelf life of peanut butter.

These findings highlight the potential of lecithin, particularly sunflower lecithin, as a natural stabilizer in peanut butter formulations. Its ability to maintain low FFA levels during storage underscores its effectiveness in preventing hydrolytic rancidity and preserving product quality.

3.6. Oil separation in Peanut butter during storage

The results in Fig. 4 demonstrates that storage periods significantly (p ≤ 0.05) influenced the oil separation content of both control and treated peanut butter samples. The results revealed that oil separation increased with prolonged storage but decreased with higher concentrations of added lecithin powder.

Fig. 4.

Effect of addition different types and levels of lecithin powder and storage periods on oil separation percent of peanut butter (P₃B)  at room temperature.

The lowest oil separation content was observed in peanut butter treated with 2 % sunflower lecithin powder (3.5 %), while the highest oil separation was recorded in the control sample (6.49 %). These findings indicate that increasing the concentration of both peanut and sunflower lecithin powder effectively reduced oil separation in peanut butter during storage.

The increase in oil separation over time in the control sample is consistent with the natural tendency of peanut butter to undergo phase separation due to the instability of its lipid matrix (Ereifej et al., 2005). The addition of lecithin, particularly at higher concentrations, significantly mitigated this issue by enhancing the emulsification and stabilization of the product.

The superior performance of sunflower lecithin in suppressing oil separation is directly linked to its higher phospholipid content (30.49 % vs. 16.98 %, Table 2). Phospholipids are potent surfactants that adsorb at the interface between the solid peanut particles, crystalline fat, and liquid oil. They reduce interfacial tension and form a stable, viscoelastic film that prevents the coalescence and migration of oil droplets. The higher concentration of these functional molecules in sunflower lecithin allows it to form a more continuous and robust network within the peanut butter matrix, effectively binding the liquid oil and preventing phase separation more efficiently than peanut lecithin (Shahidi, 2005). This underscores its value as a natural stabilizer to enhance product quality and shelf life.

3.7. Sensory evaluation of Peanut butter

As presented in Fig. 5 the sensory evaluation results for appearance, texture, flavor, and overall acceptability of peanut butter samples. The highest scores in all sensory attributes were recorded for peanut butter treated with 2 % sunflower lecithin powder, with scores of 4.17 (appearance), 4.18 (texture), 3.58 (flavor), and 3.99 (overall acceptability). In contrast, the control sample received the lowest scores: 2.33 (appearance), 1.92 (texture), 2.73 (flavor), and 2.3 (overall acceptability).

Fig. 5.

Effect of addition different types and levels of lecithin powder and storage periods on sensory properties of peanut butter.

The superior sensory scores of peanut butter treated with 2 % sunflower lecithin powder can be attributed to its enhanced emulsifying and stabilizing properties, which improve the product's texture and prevent oil separation (Shahidi, 2005). The higher phospholipid content in sunflower lecithin contributes to a smoother and more uniform consistency, which is highly preferred by consumers (Yu et al., 2022). Additionally, the reduced oil separation and improved oxidative stability likely contributed to better flavor retention and overall acceptability.

The low scores of the control sample highlight the negative impact of oil separation and texture instability on consumer perception. These findings emphasize the importance of incorporating sunflower lecithin, particularly at a 2 % concentration, to enhance the sensory quality and consumer appeal of peanut butter.

4. Conclusion

Lecithin powder extracted from crude sunflower oil demonstrated a higher content of active ingredients, particularly acetone-insoluble phosphatides, compared to lecithin derived from crude peanut oil. The oxidative stability of peanut butter improved significantly with increasing concentrations of sunflower lecithin powder, although stability declined with extended storage periods. Peanut butter treated with 2 % sunflower lecithin powder exhibited the lowest increases in peroxide value, free fatty acids, and oil separation content, highlighting its superior resistance to oxidation and rancidity. Furthermore, the addition of 2 % sunflower lecithin powder resulted in the highest sensory scores for appearance, texture, flavor, and overall acceptability, outperforming other concentrations and the control sample. These findings underscore the effectiveness of sunflower lecithin, particularly at a 2 % concentration, in enhancing the quality, stability, and consumer appeal of peanut butter. Future research should focus on exploring other natural lecithin sources, optimize processing conditions to enhance functionality, and investigate the long-term storage stability and mechanisms behind reduced oil separation.

CRediT authorship contribution statement

Mazin Mohamed Salih Ibrahim: Writing – original draft, Validation, Methodology, Investigation, Formal analysis, Conceptualization. Abdeen Elkhedir: Writing – review & editing, Supervision, Project administration, Investigation. Mahdi Abbas Saad Shakak: Writing – review & editing, Supervision. Alnazir Abderhaman Alagib: Writing – review & editing, Supervision.

Ethics statement

The sensory assessment followed the ethical standards set by the Agro-Industries Institute's Ethics Committee under the Industrial Research and Consultancy Centre (approval no. IRCC/ARFAN/2022/09). All participants provided informed consent prior to their involvement. According to the institutional guidelines and local regulations, ethical approval was not required for this type of sensory evaluation involving food products and non-vulnerable adult participants.

Funding

No financial support or funding was received for this research.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability

The data that has been used is confidential.