Introduction
The integration of natural bioactive compounds into food products has emerged as a transformative strategy to enhance their nutritional and functional properties, while aligning with consumer demands for clean and sustainable ingredients. Among these natural compounds, olive leaf extract (OLE) has gained attention for its remarkable antioxidant and antimicrobial properties, primarily owing to its high concentration of bioactive phenolics such as oleuropein. Olive leaves, a by-product of the olive oil industry, represent a largely underutilized resource with immense potential. By repurposing these leaves into functional food ingredients, the food industry can address the issues of agricultural waste while offering consumer products with added health benefits.
Cheese, particularly ripened varieties such as Cantal, are an ideal medium for incorporating functional ingredients because of their global popularity and nutritional richness. Cantal cheese, which is known for its distinct texture and flavor, undergoes a maturation process that can influence its antioxidant potential through microbial activity. This natural progression can be further amplified by fortification with bioactive extracts, such as OLE, opening avenues for enhanced shelf life, flavor stability, and health benefits.
Despite the growing interest in plant-derived food preservatives, limited research has focused on the direct incorporation of OLE into ripened cheeses. Previous studies have highlighted the fortification of dairy products, such as yogurt, with plant extracts, yet their application in cheese remains relatively unexplored. This gap underscores the importance of the present study, which investigates the impact of varying OLE concentrations on the physicochemical, microbiological, and functional properties of Cantal cheese over a 63-day storage period.
This research not only addresses the practical applications of OLE in food preservation but also aligns with broader sustainability goals by reducing agricultural waste and promoting circular economic practices. By combining tradition with innovation, this study offers valuable insights into enhancing the quality and functionality of dairy products, paving the way for healthier and more sustainable food systems.
Materials and Methods
This study adopted a systematic approach to evaluate the effects of OLE on various parameters of Cantal cheese.
Preparation of Olive Leaf Extract (OLE)
- Olive leaves from the Chemlali variety were dried, ground, and processed using an autoclave to extract bioactive compounds.
- The resulting extract was spray-dried into a powder for incorporation into cheese.
Cheese preparation
- Commercially available young Cantal cheese was used in this study.
- Four groups were created with varying OLE concentrations: 0% (control), 1%, 2%, and 3%.
- Cheese samples were pressed, vacuum-packed, and stored at 2°C for 63 days.
Analysis parameters:
- Physicochemical properties, antioxidant activity, texture, rheological behavior, color, and microbiological quality were analyzed on Days 1, 28, and 63.
- Advanced techniques, such as MIR spectroscopy and fluorescence spectroscopy, were employed to investigate the molecular structural changes.
Results
Antioxidant Activity
- OLE significantly increased the total phenolic content (TPC) and antioxidant activity of the cheese.
- Higher OLE concentrations (3%) resulted in the most substantial improvement, with antioxidant activity peaking at 7746.49 μmol TE/100 g on day 1.
Microbiological Quality
- OLE exhibited strong antimicrobial effects, particularly against spoilage and pathogenic microorganisms, such as Staphylococcus spp. and Enterococci.
- Although a mild inhibitory effect on beneficial bacteria, such as Lactococcus and Lactobacillus, was observed, the overall microbiological stability of the cheese improved significantly.
Physicochemical Properties
- The pH and fat content remained relatively stable across OLE concentrations, while the chloride content decreased slightly, potentially due to the chelating properties of oleuropein.
- The protein and dry matter contents showed minimal variation.
Texture and Rheology
- Texture profile analysis indicated an increase in hardness and cohesiveness with the addition of OLE, which was attributed to polyphenol-protein interactions.
- Dynamic oscillatory testing revealed that higher OLE concentrations reduced the elasticity of the cheese protein network.
Color
- OLE altered the color of cheese, resulting in darker and reddish hues, consistent with the natural pigmentation of olive leaf compounds.
Molecular Structure
- MIR spectroscopy highlighted significant changes in the protein and fat molecular regions, reflecting enhanced interactions with OLE.
- Fluorescence spectroscopy further supported these findings, showing shifts in the molecular environment of tryptophan residues, indicative of protein-polyphenol bonding.
Discussion
The integration of natural bioactive compounds into food products has emerged as a transformative strategy to enhance their nutritional and functional properties while aligning with consumer demands for clean-label and sustainable ingredients. Among these natural compounds, olive leaf extract (OLE) has gained attention for its remarkable antioxidant and antimicrobial properties, primarily attributed to its high concentration of bioactive phenolics such as oleuropein. Olive leaves, a byproduct of the olive oil industry, represent a largely underutilized resource with immense potential. By repurposing these leaves into functional food ingredients, the food industry can address issues of agricultural waste while offering consumers products with added health benefits.
Cheese, particularly ripened varieties like Cantal, presents an ideal medium for incorporating functional ingredients due to its global popularity and nutritional richness. Cantal cheese, known for its distinct texture and flavor, undergoes a maturation process that can influence its antioxidant potential through microbial activity. This natural progression can be further amplified by fortification with bioactive extracts like OLE, opening avenues for enhanced shelf-life, flavor stability, and health benefits.
Despite the growing interest in plant-derived food preservatives, limited research has focused on the direct incorporation of OLE into ripened cheese. Previous studies have highlighted the fortification of dairy products like yogurt with plant extracts, yet their application in cheese remains relatively unexplored. This gap underscores the importance of the present study, which investigates the impact of varying OLE concentrations on the physicochemical, microbiological, and functional properties of Cantal cheese over a 63-day storage period.
This research not only addresses the practical applications of OLE in food preservation but also aligns with broader sustainability goals by reducing agricultural waste and promoting circular economy practices. By combining tradition with innovation, the study offers valuable insights into enhancing the quality and functionality of dairy products, paving the way for healthier, more sustainable food systems.
Conclusion
This study highlights the transformative potential of olive leaf extract in enhancing the quality and functionality of Cantal cheese. By leveraging the natural bioactivity of OLE, cheese producers can not only improve product quality but also contribute to sustainable food practices. These findings serve as a foundation for future innovations in the dairy industry, emphasizing the value of integrating sustainability and health-driven approaches into food production.
Read all at: Tarchi, I., Bouaziz, M., Bhat, Z. F., & Aït-Kaddour, A. (2024). Effect of olive leaf extract on the quality of Cantal cheese. Food Chemistry: X, 101966. https://doi.org/10.1016/j.fochx.2024.101966