ABSTRACT
Quality of a fruit is defined as a combination of features that distinguish an individual from its similar ones based on its standard. It determines how safe is it to consume a product postharvest, and hence its extent of acceptance and grading. Quality is defined on the basis of certain external features such as shape, weight, color, firmness, temperature, smoothness, taste, apparent spots and a few internal features like ripeness, sugar content, biochemical composition, pigments, dry matter and pectic ingredients. Scrutiny of fruits and vegetables for determining the quality is done either by human vision, i.e., manual observation or by machine vision, i.e., using sensors. Human monitoring requires a panel of 10–15 trained experts to check the shape, dimensions, age, ripeness, and other features of fruits and vegetables. Machine based scrutiny involves sensors and instruments and involvement of mathematical algorithms to measure quality of fruit. The conventional machine-based practice of examining the quality may damage the fruit itself, hence known as destructive method, however the advanced technique used for quality monitoring and control works without destroying the product, hence termed as non-destructive or non-invasive methods of monitoring. Non-destructive monitoring methods used in commercial applications include mechanical methods like impact, vibration analysis and electronic nose; optical methods like visible/near-infrared spectroscopy, time and space resolved spectroscopy and electronic eye; magnetic methods like magnetic resonance imaging and electrical conductivity method; acoustic methods 268like ultrasonics and impulse response method; and other dynamic methods like X-ray and CT scan.
