# Utilization of Yacon Damaged Roots as a Source of FOS-Enriched Sweet-Tasting Syrup
## 1 Introduction  
Yacon (_Smallanthus sonchifolus_) is a perineal plant from the family Asteraceae characteristic of the Andean region. This crop has been promoting the development of many Andean communities with low incomes, where it represents a relevant food source. The adaptability of yacon to moderate edaphoclimate conditions has also allowed the expansion of yacon cultivation to many other geographical areas, such as in the USA, New Zealand, the Czech Republic, Italy [1], and Portugal. In Europe, the most common varieties are Morado, Blancom Llanera, among others, that have been cultivated according to their adaptability to the local edaphoclimate conditions [2]. Depending on the variety, yacon plants form underground tuberous roots of yellowish, pink, purple, or brownish color, with an average of 15-20 cm long, a thickness of 10 cm, and a weight that might reach 2 kg [3]. Yacon cultivation presents a major issue related to its breakage during harvesting, packaging, and transportation. Such a process causes the darkening of the damaged tissues by polyphenol oxidation reactions, which are perceived as spoiled by the consumer [3]. Inthis context, the damaged roots account for an agro-industrial by-product that, when not channeled to low-commercial-value applications, is treated as an agro-industrial disposable due to its high perishability. Many studies have focused on yacon valuation for flour applications [4], dried chips [5], or beverages [6]. However, the current association between type 2 diabetes, obesity, tooth decay, and high daily intakes of sugar, highlighted by the World Health Organization [7], has promoted the use of yacon for sweetening purposes in the form of syrups [8]. This results from the fact that, unlike many other plants that accumulate starch, yacon accumulates inulin, a polysaccharide composed of a sucrose unit extended by 1)\(\rightarrow\)Fruf-(\(\beta\)2\(\rightarrow\) chain [9; 10]. This structure differs from that of branched inulins, such as those found in agave, that present long 1)\(\rightarrow\)Fruf-(\(\beta\)2\(\rightarrow\) and short 6)\(\rightarrow\)Fruf-(\(\beta\)2\(\rightarrow\) chains at C1 and C6 of fructose of the sucrose unit, respectively. In agave inulins, the glucose unit of sucrose might also be branched at C6 with Fru [11]. Although the high temperatures of extraction can promote hydrolysis and debranching, these structural features are still present in the extracted fractions, allowing us to clearly distinguish linear and branched fructans. The decrease in the degree of polymerization of fructans due to the high temperatures of extraction also results in an increase in the sweetness of the products [12]. For linear inulin and derived fructologosaccharides (FOS), the estimated sweetness sensation is 10% and 40% compared to sucrose [13]. Notably, they are not degraded by digestive enzymes. Consequently, both inulin and FOS have a role as dietary fiber and are reported to stimulate the growth of beneficial bacteria in the gut, acting as prebiotics [4; 14]. In addition, antioxidants such as chlorogenic and caffeic acid derivatives and minerals such as potassium, calcium, and phosphorus, which also comprise relevant yacon components [15], together with the low content of fructose, glucose, and sucrose when compared to fruits, render yacon a low-caloric and high-nutrition food [16]. As a natural product, yacon has the potential to be a \"clean label\" sugar reduction strategy, currently demanded by informed consumers [8]. Accounting for this, yacon-damaged roots could be mitigated as agricultural by-products by their use in the development of syrups for sugar reduction in foods. This work studies the potential use of the damaged roots of Hualqui and Crespo yacon varieties harvested in Portugal, with a specific emphasis on the carbohydrates present to produce syrups. This aims to comprehensively understand the fate of carbohydrates, especially when using \"clean label\" technological adjuvants, such as lemon juice.