Insights into Yacon drying: Applications and challenges ahead

Abstract

Yacon (Smallanthus sonchifolius) is a tuberous root with notable functional properties, primarily due to its high content of fructooligosaccharides (FOS) (38–64 % dry basis) and low glycemic index, which provide recognized health benefits, including prebiotic effects. However, its high moisture content (80–90 % wet basis) results in rapid perishability, limiting its commercial utilization. This review provides a comprehensive analysis of the effects of different drying techniques—including convective drying, freeze drying, sun/solar drying, foam-mat drying, spray drying, and microwave-assisted drying—on the physicochemical properties, bioactive compound retention, and functional quality of yacon. Quantitative comparisons reveal that microwave-assisted drying combined with pulsed vacuum osmotic dehydration achieves the highest FOS retention (up to 95.74 %) and reduces drying time by 50 %, while freeze-drying provides excellent preservation of phenolic compounds but is limited by high energy consumption and operational costs. Conversely, convective drying, though cost-effective, often leads to significant FOS degradation (retention as low as ∼38 %) and structural collapse. Additionally, this review discusses the impact of pretreatments—such as blanching, ethanol immersion, and ultrasound—on drying kinetics, color preservation, and bioactive retention. Industrial applications are explored, highlighting the use of dried yacon in functional flours, probiotic carriers, and as a sugar substitute in bakery products, despite existing barriers related to production costs and consumer awareness. The review also outlines critical research gaps, including the influence of soil pH and climate on FOS content, the need for optimization of energy consumption, and strategies to enhance process scalability. These insights aim to support the sustainable industrialization of yacon-based products and promote the wider adoption of this underutilized crop in functional food markets.