Parsley Extract Helps Prevent Oil Spoilage in Soybean Emulsions

Jenn Hoskins
20th May, 2024

Parsley Extract Helps Prevent Oil Spoilage in Soybean Emulsions

Image Source: Natural Science News, 2024

Key Findings

  • The University of Padova's study found that acid hydrolysis significantly boosts the antioxidant activity of parsley extracts in soybean oil-in-water emulsions
  • By converting glycosidic polyphenols to aglycones, the extracts showed higher total phenolic content and improved radical scavenging activity
  • The enhanced extracts extended the shelf-life of emulsions by delaying lipid oxidation, increasing the lag phase for hexanal formation from 6 to 11 days
The University of Padova recently conducted a study investigating the effects of acid hydrolysis on the antioxidant activity of parsley extracts in soybean oil-in-water emulsions[1]. This research aimed to address the limitations of phenolic compounds in glycoside form, which often show reduced antioxidant activity in certain food systems. By converting glycosidic polyphenols to their aglycone forms through acid hydrolysis, the study sought to enhance the antioxidant properties of these extracts, thereby extending the shelf-life of emulsion-based foods. In the study, parsley extracts were obtained using an ultrasound-assisted extraction method. The extracts were then subjected to various acid hydrolysis conditions to maximize total phenolic content (TPC) and improve 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. The optimal conditions found were 0.6 M HCl for 2 hours at 80°C. Under these conditions, the TPC reached 716.92 ± 24.43 µmol gallic acid equivalent (GAE)/L, and the DPPH radical scavenging activity was 66.89 ± 1.63%. The researchers observed that acid hydrolysis not only increased the concentrations of individual polyphenols but also led to the release of new phenolics, such as myricetin and gallic acid. This transformation significantly enhanced the metal-chelating and ferric-reducing activities of the extracts. In practical terms, when the acid-hydrolyzed extract was used in a soybean oil-in-water emulsion with a TPC of 400 µmol GAE/L, it extended the lag phase for headspace hexanal formation to 11 days, compared to just 6 days for the unhydrolyzed extract. This indicates a substantial improvement in delaying lipid oxidation. This study builds on earlier research that explored antioxidant interactions in oil-in-water emulsions. For instance, previous findings demonstrated that myricetin could regenerate oxidized α-tocopherol and slow its degradation, thereby exhibiting synergistic antioxidant effects at neutral pH levels[2]. However, myricetin showed antagonistic behavior at acidic pH due to its high ferric-reducing activity. The current study's use of acid hydrolysis to release myricetin from parsley extracts aligns with these findings, suggesting that the form in which polyphenols are present can significantly impact their antioxidant efficacy. Additionally, the research complements studies that have examined other methods to enhance antioxidant activity. For example, phosphatidylethanolamine (PE) has been shown to regenerate oxidized α-tocopherol, thus delaying lipid oxidation in emulsions and bulk oil[3]. The current study's approach of converting glycosidic polyphenols to aglycones via acid hydrolysis offers an alternative strategy to achieve similar outcomes. Moreover, the increased metal-chelating and ferric-reducing activities observed in the acid-hydrolyzed extracts address concerns about the prooxidant activity of natural antioxidants in the presence of transition metals, such as Fe and Cu[4]. By enhancing the ability of the extracts to neutralize these metals, the study provides a more robust antioxidant solution for food systems. The research also ties into findings on the extraction methods and antioxidant capacity of various medicinal plants. For example, prolonged extraction and hydrolysis have been shown to improve the content of phenolic compounds and antioxidant capacity in plants like blackberry leaves and lemon balm[5]. The current study's use of ultrasound-assisted extraction followed by acid hydrolysis mirrors these methods, further validating the approach. In conclusion, the University of Padova's study demonstrates that acid hydrolysis can significantly enhance the antioxidant activity of parsley extracts in soybean oil-in-water emulsions. By converting glycosidic polyphenols to aglycones, the extracts become more effective in delaying lipid oxidation, thereby extending the shelf-life of emulsion-based foods. This research not only builds on previous findings but also provides a practical solution to improve food preservation through natural antioxidants.

NutritionBiochemPlant Science

References

Main Study

1) Acid-hydrolyzed phenolic extract of parsley (Petroselinum crispum L.) leaves inhibits lipid oxidation in soybean oil-in-water emulsions.

Published 19th May, 2024

https://doi.org/10.1016/j.foodres.2024.114452

Related Studies

2) Synergistic Mechanisms of Interactions between Myricetin or Taxifolin with α-Tocopherol in Oil-in-Water Emulsions.

https://doi.org/10.1021/acs.jafc.3c01226

3) Enzymatic Modification of Lecithin for Improved Antioxidant Activity in Combination with Tocopherol in Emulsions and Bulk Oil.

https://doi.org/10.1021/acs.jafc.2c05182

4) Prooxidant Activity of Polyphenols, Flavonoids, Anthocyanins and Carotenoids: Updated Review of Mechanisms and Catalyzing Metals.

https://doi.org/10.1002/ptr.5643

5) Phenolic composition and antioxidant properties of some traditionally used medicinal plants affected by the extraction time and hydrolysis.

https://doi.org/10.1002/pca.1264


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