Structural and Functional Properties of Fiber From Psyllium (Plantago ovata) Husk: Current Knowledge and Strategies to Expand Its Application in Food and Beyond

Psyllium husk fiber, from the milled surface of Plantago ovata seeds, is known for its high viscosity and gelling capacity, making it a widespread health supplement with benefits for satiety, glycemic control, gastrointestinal and cardiovascular health, as well as a texturizer, stabilizer, and fat and gluten replacement. Nevertheless, its application often comes with certain challenges, such as difficulties in adjusting the hydration level, gumminess, and color change. The positive and negative results of the fiber implementation are a consequence of its unique gelation profile and high water uptake. Therefore, a need to uncover the structure and rheological behavior has yielded detailed studies on its fundamental properties, as well as research with the aim of modifying the behavior of fiber for easier application in food products. This review addresses the current literature on the nutritional and health benefits of psyllium, its rheological characterization, and the pros and cons of its application in diverse food groups. Novel approaches to expand its use by modifying its relatively narrow functionality are also suggested, such as fractionation, modification, and genetic strategies. Moreover, a new perspective and future direction for research are discussed, which can also be applied to other highly viscous fibers. This paper serves as an overview of the principal and practical properties of fiber and connects insights from multiple avenues of its exploration with the aim of facilitating its expanded use, not only in food but also in other applications that employ psyllium's unique functionalities.