Analysis of Aroma Compounds in Healthy and Diseased Orange Juice

Greg Howard
2nd May, 2024

Analysis of Aroma Compounds in Healthy and Diseased Orange Juice

Image Source: Natural Science News, 2024

Key Findings

  • Researchers found that citrus black spot (CBS) increases the total volatile content in citrus fruits, affecting aroma
  • CBS infection causes more floral and fruity aromas in juice, and enhances citrusy, floral, and green aromas in essential oils
  • The study identified specific marker compounds in juice and essential oils that can serve as fingerprints for CBS infection levels
Citrus fruits are not only beloved for their vibrant flavors but also for their aromatic appeal. However, the quality of these fruits can be compromised by various diseases, one of which is citrus black spot (CBS). CBS, caused by the fungus Phyllosticta citricarpa, leads to unsightly blemishes on the rind of citrus fruits. Researchers from Southwest University have recently delved into how CBS affects the aromatic profile of citrus fruits[1]. This study is particularly relevant as the aroma of citrus fruits is a key factor in consumer satisfaction and marketability. The study aimed to identify changes in the volatile compounds of citrus fruits when infected by CBS. Volatile compounds are chemicals that can easily become gases and contribute significantly to a fruit's aroma. Using gas chromatography-mass spectrometry (GC-MS), a technique that can separate and identify small molecules in a mixture, the researchers analyzed both orange juice and essential oil samples from fruits with varying levels of CBS infection. The findings revealed that CBS infection led to an increase in the total volatile content, especially in the juice of fruits with severe infections and the essential oil of moderately infected fruits. This increase was associated with heightened floral and fruity aromas, as well as off-flavors, while the green aroma typically found in citrus juice decreased. In the essential oil, citrusy, floral, and green aromas were more pronounced in CBS-infected samples. To better understand these changes, the researchers employed a method known as orthogonal partial least-square discriminant analysis (OPLS-DA). This statistical tool helps to identify potential marker compounds that can distinguish between different conditions—in this case, levels of CBS infection. Six potential markers were identified in the citrus juice and five in the essential oil. These markers can be seen as fingerprints of CBS infection, offering insights into how the disease alters the fruit's aromatic profile. This study builds on earlier research that has explored the aromatic compounds in citrus fruits. A previous study[2] quantified odor-active compounds in Valencia late and Navel oranges, identifying key fruity, grassy, and citrus-like odorants that contribute to their distinct aromas. Another study[3] investigated off-flavor compounds in Ponkan mandarin juice, finding that light exposure could induce off-flavors by promoting the formation of certain volatile sulfur compounds (VSCs). Additionally, research on grapefruit[4] showed how Huanglongbing (HLB), another citrus disease, alters the volatile profiles, reducing the content of key flavor compounds like nootkatone. The current study adds to this body of knowledge by showing how CBS specifically influences the volatile profiles of citrus fruits. It not only identifies the increase in total volatile content but also the nuanced shifts in aromatic profiles that could affect consumer perception. This research is crucial as it provides a deeper understanding of the effects of CBS on citrus aroma, which could inform strategies for disease management and breeding programs aimed at improving fruit quality. Moreover, the identification of potential aromatic markers for CBS could lead to the development of diagnostic tools for early detection and quantification of infection levels. This could be particularly useful for growers and the citrus industry as a whole, enabling them to take timely action to minimize the impact of CBS on their crops. In summary, the study from Southwest University has expanded our understanding of how citrus black spot disease can alter the volatile compounds and, consequently, the aroma profiles of citrus fruits. By identifying specific changes in aromatic profiles and potential markers for CBS infection, this research contributes to the broader efforts to protect citrus fruit quality and ensure the continued enjoyment of these flavorful and aromatic fruits.

FruitsBiochemPlant Science

References

Main Study

1) Characterization of volatile compounds from healthy and citrus black spot-infected Valencia orange juice and essential oil by using gas chromatography-mass spectrometry.

Published 30th June, 2024 (future Journal edition)

https://doi.org/10.1016/j.fochx.2024.101374

Related Studies

2) Evaluation of aroma differences between hand-squeezed juices from Valencia late and Navel oranges by quantitation of key odorants and flavor reconstitution experiments.

Journal: Journal of agricultural and food chemistry, Issue: Vol 49, Issue 5, May 2001

3) Identification of Light-Induced Key Off-Flavors in Ponkan Mandarin Juice Using MDGC-MS/O and GC-MS/PFPD.

https://doi.org/10.1021/acs.jafc.1c05465

4) Effect of Huanglongbing on the Volatile Organic Compound Profile of Fruit Juice and Peel Oil in 'Ray Ruby' Grapefruit.

https://doi.org/10.3390/foods12040713


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