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Science News: Wondrous blue: Nanostructures and pigments in fruit coloration

– A.P., Editor

Fruits present a stunning array of colors, ranging from the fiery red of strawberries to the sunny yellow of bananas, each contributing to the visual delight of nature's bounty. Yet, amidst this colorful tapestry, the hue of blue remains a rarity, gracing only a select few fruits with its mesmerizing presence. Exploring the mystery behind blue fruits unveils a captivating narrative of nanostructures and pigments, shedding light on the intricate relationship between science and aesthetics. In this exploration, the unassuming blueberry emerges as a key player, its striking blue hue hiding secrets within its waxy coating.

Researchers have unraveled the secret behind the blueberry's captivating color: the intricate structure of its waxy coating. Blue-colored fruits like blueberries (Vaccinium corymbosum), grapes (Vitis vinifera), and certain plums feature nanostructures embedded within their waxy covers. These nanostructures scatter blue and ultraviolet light, resulting in the vivid blue appearance perceived by humans. Interestingly, birds, with their ability to see ultraviolet light, likely view these fruits as blue-UV treats.

Despite containing anthocyanin, a pigment commonly associated with dark red hues, blueberries exhibit a striking blue coloration due to the unique properties of their waxy outer layers. The revelation of these structural intricacies presents intriguing possibilities. Scientists envision replicating the color-forming capabilities of blueberries to innovate approaches for imparting a blue tint to plastics or cosmetics, highlighting its non-staining nature.

To unravel the mysteries of fruit coatings, researchers conducted meticulous analyses using scanning electron microscopy. Their observations unveiled an array of minuscule molecular structures within the wax layers, adept at scattering blue and UV light. In a remarkable feat, the researchers successfully replicated this effect in laboratory settings. By dissolving wax from Oregon grapes (Mahonia aquifolium) with chloroform and allowing it to recrystallize on a black surface, they observed the restoration of its distinct blue hue. This breakthrough unveils promising applications of nature-inspired coloration techniques across industries, promising innovations yet to unfold in the fascinating interplay between science and aesthetics within fruit coloration.

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