A Sustainable Alternative to Measuring Calcium in Orange Juice

Orange juice remains a popular beverage worldwide because of some of its nutritional benefits, including its vitamin C and calcium content. Recently, a study that was published in the Journal of Food Composition and Analysis proposed and tested a new approach for monitoring the nutritional quality of orange juice (1). This study, which was led by researchers from the Universidad de la República in Montevideo, Uruguay, demonstrates that near-infrared spectroscopy (NIR) can serve as a reliable and sustainable alternative to traditional analytical methods for evaluating juice quality.

Orange fruit and glass of juice on brown wooden background | Image Credit: © avirid - stock.adobe.com.

What are the nutritional benefits of orange juice?

Orange juice is one of the most popular juices, and it is primarily consumed at breakfast. Known for its refreshing taste, orange juice also contains nutritional benefits, but these vary depending on the type of juice. For example, there are some varieties that contain a lot of added sugars and very little juice (2). However, fresh-squeezed orange juice contains some of the health benefits consumers look for in the beverage (2).

Uruguay is a country that produces a sizable amount of orange juice, thanks to its abundance of citrus farming in the country. The country is the second-largest citrus exporter in Latin America, and among the top twenty citrus exporters globally (1). As a result, the economic importance of orange juice in Uruguay underscores the need for modern, efficient, and environmentally friendly techniques to ensure that consumers worldwide receive high-quality juice (1).

What did the study focus on?

In their study, the researchers focused on juice made from Valencia oranges (Citrus sinensis L. Osbeck), the primary cultivar grown for juice production in Uruguay. The researchers collected fruits from the Paysandú region, one of the main hubs in the country where citrus farming takes place. The fruits were collected during the optimal harvesting season from September to November (1). Over three months, they sampled 120 fruits across 12 batches, ensuring a robust dataset for their analysis (1).

In previous studies, standard chemical methods were used to analyze the nutritional components of orange juice and similar products. However, these methods are resource-intensive and require significant time, reagents, and laboratory infrastructure (1).

The researchers decided to test whether NIR spectroscopy can speed up analysis time without sacrificing accuracy. The results achieved were encouraging. Calcium, an essential nutrient that supports bone health and metabolic functions, showed a strong correlation between standard chemical analyses and NIR results (1). Specifically, the study reported a slope greater than 0.94 and a Residual Predictive Deviation (RPD) above 3, benchmarks that indicate robust predictive accuracy (1). This discovery suggests that NIR could be adopted as a practical tool for routine calcium analysis in orange juice, reducing costs while aligning with the principles of Green Analytical Chemistry (GAC).

What were some of the other findings in the study?

One of the more interesting findings from this study is that calcium and other metals forming coordinated bonds with organic molecules could be reliably measured by NIR, whereas elements such as iron demonstrated weaker correlations (1). This highlights both the strengths and limitations of using NIR spectroscopy in food analysis, suggesting that it is best suited for certain nutrients rather than all mineral components.

Beyond its technical contributions, the research has broader implications for the citrus industry. By adopting NIR spectroscopy, producers could streamline quality control processes, making them faster, greener, and more affordable. This could help exporters like Uruguay maintain their competitive edge while responding to growing consumer concerns about sustainability and food quality (1).

The study reaffirms the nutritional value of Valencia orange juice from Uruguay, confirming its strong health profile while demonstrating that advanced analytical technologies can help safeguard and promote this iconic beverage (1). As consumer demand for transparency and sustainability grows, the integration of NIR spectroscopy into quality monitoring may mark a significant step forward for the global juice industry.

References

1. Miro, E.; Boido, E.; Farina, L; et al. Comparative Study of NIR Spectroscopy and Traditional Analytical Methods in the Determination of Orange Juice Nutritional Quality Parameters. J. Food Comp. Anal. 2025, 140, 107276. DOI: 10.1016/j.jfca.2025.107276
2. McCulloch, M. Is Orange Juice Good or Bad for You? Healthline. Available at: https://www.healthline.com/nutrition/orange-juice (accessed 2025-09-19).