Gelation mechanism of alkali induced heat-set konjac glucomannan gel

Konjac glucomannan (KGM) is a functional polysaccharide isolated from the tubers of Amorphophallus konjac C. Koch known for its superior heat-set gel-forming capacity. Although commonly used for decades in food industry, KGM's unique gelling behavior has drawn lots of attention in recent years, and it also presents significant challenges especially when elucidating its gelation mechanism. In this review, recent progress and developments on gelation mechanism of the alkali induced heat-set KGM gel have been summarized on many key topics, including the experimental techniques, differences between gel preparation routes, and most importantly, correlating morphological/structural features and intermolecular interactions during the gelling process. In addition, impacts of internal and external factors on the KGM gelation, especially the mechanically related properties, have been also discussed. The understanding of KGM gelation has been evolving over the last decade. The possible gelation includes the deacetylation induced by alkali addition, the stretch and physically association of chains upon heat-treatment, and the three-dimensional gel network established on the agglomeration of random network. Although insights have been provided into the gelation mechanism of KGM in this review which uncovers the foundational aspects of structure/property relationships in terms of KGM gel. There are still unanswered questions and areas, in particular the alkali and heat-treatment induced intermolecular association mechanism, where further research employing some state-of-the-art in situ characterization techniques as well as computation models is required.