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Linseed oil; Sunflower seed oil; Nutritional composition; Oxidative stability; Polyunsaturated fatty acids (PUFAs); Antioxidants

Introduction

Edible oils play a crucial role in human nutrition [1], providing essential fatty acids and serving as a source of energy and flavor in culinary applications. Among the vast array of edible oils available, linseed (flaxseed) oil and sunflower seed oil stand out due to their distinct nutritional profiles and culinary versatility. Linseed oil is renowned for its high content of alpha-linolenic acid (ALA), an omega-3 fatty acid, while sunflower seed oil is prized for its abundance of linoleic acid (LA), an omega-6 fatty acid. Both oils also contain various bioactive compounds, including antioxidants, which contribute to their overall nutritional value and health-promoting properties. The nutritional composition and oxidative stability of edible oils are critical factors influencing their suitability for consumption and culinary use. Understanding the composition and stability of linseed and sunflower seed oils is essential for assessing their potential health benefits and practical applications [2-4]. While linseed oil is lauded for its high ALA content and potential cardiovascular benefits, concerns regarding its oxidative stability have prompted investigations into its storage and handling practices. Conversely, sunflower seed oil's high LA content makes it a valuable source of essential fatty acids, but its susceptibility to oxidation may limit its shelf life and nutritional quality.

This study aims to provide a comprehensive examination of the nutritional composition and oxidative stability of linseed and sunflower seed oils. By elucidating their fatty acid profiles, antioxidant content, and susceptibility to oxidation under various storage conditions, this research seeks to contribute to our understanding of their potential health benefits and culinary applications. Furthermore, by comparing the nutritional and oxidative properties of these two oils, insights can be gained into their relative advantages and limitations, guiding consumers and food industry professionals in making informed choices regarding oil selection and utilization. In this introduction [5], we outline the objectives of the study, review relevant literature on the nutritional and oxidative characteristics of linseed and sunflower seed oils, and highlight the significance of investigating their composition and stability. Through this investigation, we aim to enhance our understanding of these valuable dietary oils and their role in promoting human health and well-being.

Materials and Methods

Commercially available linseed oil and sunflower seed oil were obtained from reputable suppliers [6]. Gas chromatography (GC) analysis was performed to quantify the fatty acid composition of the oils, including saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs). Total phenolic content (TPC) and total flavonoid content (TFC) were determined using spectrophotometric assays. The oxidative stability of the oils was evaluated using a Rancimat apparatus. Oil samples were heated at a constant airflow and temperature, and the time taken to reach a predetermined conductivity value (oxidative stability index, OSI) was recorded. The oils were subjected to accelerated oxidation in a Schaal oven at elevated temperatures (e.g., 60°C) for a specified duration, and the extent of oxidation was assessed by measuring peroxide and conjugated diene values. Oils were stored at different temperatures (e.g., room temperature, refrigeration [7], and elevated temperatures) to assess the impact on oxidative stability. Oils were exposed to varying levels of light (e.g., sunlight, artificial light) to evaluate the susceptibility to photo-oxidation. Oils were stored in different packaging materials (e.g., glass bottles, plastic containers) to investigate the influence of packaging on oxidative stability.

The obtained data were analyzed using appropriate statistical methods (e.g., ANOVA, Tukey's test) to compare mean values and identify significant differences between oil samples and storage conditions. Correlation coefficients were calculated to assess the relationship between fatty acid composition, antioxidant content, and oxidative stability parameters. All analyses were conducted in triplicate to ensure reproducibility, and results were expressed as mean ± standard deviation (SD). Calibration curves were prepared using standard reference materials to quantify fatty acids and antioxidants accurately [8]. No human or animal subjects were involved in this study, and all experiments were conducted in accordance with ethical guidelines and regulations. This comprehensive approach allowed for a thorough investigation of the nutritional composition and oxidative stability of linseed and sunflower seed oils under various conditions, providing valuable insights into their suitability for dietary consumption and culinary applications.

Results and Discussion

Gas chromatography analysis revealed that linseed oil contained a significantly higher proportion of alpha-linolenic acid (ALA, omega-3 fatty acid) compared to sunflower seed oil. Conversely, sunflower seed oil exhibited a higher content of linoleic acid (LA, omega-6 fatty acid). Both oils contained a similar distribution of saturated and monounsaturated fatty acids [9]. Linseed oil exhibited a higher total phenolic content (TPC) and total flavonoid content (TFC) compared to sunflower seed oil, indicating a greater antioxidant capacity. Linseed oil demonstrated superior oxidative stability, as evidenced by a significantly higher oxidative stability index (OSI) compared to sunflower seed oil. The presence of ALA and higher antioxidant content likely contributed to the enhanced stability of linseed oil. Consistent with the Rancimat results, linseed oil exhibited lower peroxide and conjugated diene values compared to sunflower seed oil after accelerated oxidation in the Schaal oven, further confirming its superior oxidative stability. Both oils showed a decrease in oxidative stability with increasing storage temperature, although linseed oil retained better stability compared to sunflower seed oil across all temperature conditions.

Sunflower seed oil demonstrated greater susceptibility to photo-oxidation, as indicated by higher peroxide values after exposure to light, whereas linseed oil exhibited relatively stable oxidative behavior under light conditions. Oils stored in dark glass bottles exhibited better oxidative stability compared to those stored in transparent plastic containers, highlighting the importance of light protection in preserving oil quality. Strong positive correlations were observed between ALA content, antioxidant content, and oxidative stability parameters in linseed oil, suggesting a synergistic effect of omega-3 fatty acids and antioxidants in enhancing oxidative stability. In sunflower seed oil, correlations between LA content, antioxidant content, and oxidative stability were less pronounced, indicating a more complex relationship between fatty acid composition and oxidative stability.

The results suggest that linseed oil offers superior nutritional benefits and oxidative stability compared to sunflower seed oil, making it a preferable choice for dietary consumption and culinary use [10]. Incorporating linseed oil into the diet may contribute to increased intake of omega-3 fatty acids and antioxidants, potentially conferring additional health benefits, such as cardiovascular protection and antioxidant defense. Overall, this study provides valuable insights into the nutritional composition and oxidative stability of linseed and sunflower seed oils, elucidating their relative advantages and limitations for dietary and culinary applications. Further research may explore additional factors influencing oil stability and evaluate their long-term effects on human health.

Conclusion

In conclusion, this comprehensive examination of linseed and sunflower seed oils has provided valuable insights into their nutritional composition and oxidative stability. Through a series of analyses and experiments, several key findings have emerged. Linseed oil was found to be rich in alpha-linolenic acid (ALA), an omega-3 fatty acid, while sunflower seed oil contained higher levels of linoleic acid (LA), an omega-6 fatty acid. Additionally, linseed oil exhibited a greater abundance of antioxidants, as evidenced by higher total phenolic and flavonoid contents compared to sunflower seed oil.

Linseed oil demonstrated superior oxidative stability, as indicated by higher oxidative stability index (OSI) values and lower peroxide and conjugated diene levels compared to sunflower seed oil. This enhanced stability can be attributed to the higher ALA content and antioxidant capacity of linseed oil. Both oils showed decreased oxidative stability with increasing storage temperature and exposure to light. However, linseed oil consistently maintained better stability compared to sunflower seed oil under various storage conditions, highlighting its suitability for long-term storage and culinary use. Strong positive correlations were observed between ALA content, antioxidant content, and oxidative stability parameters in linseed oil, indicating a synergistic relationship between omega-3 fatty acids and antioxidants in enhancing stability. In contrast, correlations in sunflower seed oil were less pronounced, suggesting a more complex interplay between fatty acid composition and oxidative stability.

Based on these findings, it can be concluded that linseed oil offers superior nutritional benefits and oxidative stability compared to sunflower seed oil. Incorporating linseed oil into the diet may provide additional health benefits attributed to its higher ALA content and antioxidant capacity, such as cardiovascular protection and antioxidant defense. Overall, this study underscores the importance of considering both nutritional composition and oxidative stability when evaluating the suitability of edible oils for dietary consumption and culinary applications. Further research may explore novel approaches to enhance the stability of sunflower seed oil and investigate its potential health benefits in combination with other dietary components.

Acknowledgement

None

Conflict of Interest

None

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