A team of chemists at Christ University in Bengaluru has transformed a traditional dye wood into a practical tool for addressing food safety concerns, specifically in detecting milk spoilage. By utilizing extracts from Caesalpinia sappan L., commonly known as sappan heartwood, the researchers have created a natural color indicator that changes color as milk loses its freshness.
This innovative indicator has the potential to be integrated into smart packaging, alerting consumers when milk and other perishable items are at risk of spoiling. The researchers emphasize that this real-time monitoring could significantly reduce food waste and help prevent unsafe consumption. With India producing over 239 million tonnes of milk each year—accounting for approximately one-fourth of the global total—milk spoilage is a pressing issue, particularly in regions with inadequate refrigeration.
The research, which merges traditional plant knowledge with contemporary chemistry, was recently published in the journal Food Analytical Methods, under Springer Nature. It is also the subject of a patent application in India. The study was led by Vinod TP, an associate professor in the department of chemistry at Christ University, along with doctoral researchers Simran Nagpal and Chaithra KP. The ideation process also included contributions from Sreelekha S from Tagore Memorial Higher Secondary School in Kannur.
The indicator solution is prepared by boiling sappan heartwood in water, which exhibits a strong response to changes in pH, a critical chemical indicator of milk spoilage. Fresh milk keeps the solution a vibrant orange-red color, which shifts to orange and ultimately yellow as acidity increases. These color changes reflect the pH decline from about 7.0 in fresh milk to approximately 3.5 in spoiled samples. The transformation is attributed to brazilein, a natural pigment found in sappan heartwood, recognized for its medicinal and dyeing properties. Its stability under light and heat makes it suitable for practical applications.
To enhance accessibility, the research team demonstrated that the color changes could be captured and analyzed using a smartphone camera. By processing digital images through RGB (red, green, blue) analysis, the “green chromatic shift” serves as a dependable indicator of freshness. Vinod noted, “This approach eliminates the need for laboratory tools or trained personnel. Anyone can visually assess the milk”s condition or utilize a smartphone app.”
By integrating traditional plant chemistry with modern digital tools, the team from Christ University has showcased a sustainable innovation that effectively translates color changes into a meaningful measure of food safety.
