Non-Destructive, Label Free Evaluation of the Biochemical Profile Associated With the Growth and Ripening Process of Jamun Fruit by Confocal Micro Raman Spectroscopy

Abstract

The evaluation of the maturity and ripening of fruits is important from both consumer and industry point of view in order to produce high quality horticultural products. This requires the need to explore the potential of reliable, cost effective and fast data acquiring techniques that have practical applicability for the nondestructive monitoring of fruits. Therefore, the present study explores the utility of confocal micro Raman spectroscopy for the nondestructive, extraction-free evaluation of biochemical changes associated with the ripening of jamun fruits. For this, the exocarp, mesocarp and seed of the jamun fruits have been examined at green, green-pink, reddish-pink, light-purple, dark-purple and blackish-blue stages of growth and ripening. The analysis of the acquired Raman spectrum of the exocarp and mesocarp of jamun shows the spectral features of starch, glucose, fructose, carotenoids, anthocyanins and flavonoids. In addition, seeds are rich in carotenoids and flavonoids. The decrease in the intensity of the starch band and simultaneous increase in the intensity of glucose and fructose bands at the onset of ripening indicate that ripening is associated with a decrease in non-reducing sugars with subsequent accumulation of reducing sugars. The appearance of the spectral features of anthocyanins and carotenoids in the ripe fruits indicates significant accumulation during ripening. The obtained spectral features may be used to monitor the maturity and ripening of the fruits in order to determine the appropriate harvest time to maximize fruit quality and minimize postharvest losses.