Recent developments in extraction and modification of pectin from unconventional fruit sources

Enormous levels of peel, core, seed, and pomace, weighing up to 50 % of fruit mass, end up as discards. Unused fruit parts are often regarded as zero-value wastes, dumped in landfills, adversely impacting the environment, or used in animal feeds. Of late, fruit discards are increasingly recognized as a valuable reserve of bioresources, highlighting the promising scope for 'resource recovery', 'zero discards', and 'upcycling'. One such popular ingredient that can be obtained is pectin. Although pectin is a well-reported molecule, in the past 5 years, significant advances have been made in developing innovative solutions in extraction and modification for improved functionality and application versatility. This review considers this aspect, focusing on pectin from discards of fruits, other than the conventional sources such as orange and apple peel/pomace. Traditional and emerging concepts of pectin processing are detailed, highlighting the dynamic landscape in research on pectin in food, nutraceuticals, and biomedical applications. Studies demonstrate that novel extraction and modification techniques not only process this macromolecule to meet specific application requirements but also are a pathway towards sustainability. Following this concern, an overview of industrial upscaling of pectin extraction/modification and associated environmental or economic trade-offs is discussed. Moreover, the variety, fruit portion, maturation stage, storage, and several such variables that critically decide the source-specific chemistry of pectin have also been discussed but need better focus.