# Utilization of Yacon Damaged Roots as a Source of FOS-Enriched Sweet-Tasting Syrup
## 3 Results and Discussion
### Syrup Production
#### 3.2.1 Effect of Citric Acid Concentration on Syrup Properties  
The addition of 0.1% CitA to yacon juice decreased the pH from 6.0 to the range of 4.9-5.1 (Table 3). Upon concentration, the water loss was 87-90%, resulting in syrups of a dark/brown color (Figure S1) presenting 68-73 \({}^{\circ}\)Brix and containing 72-79% (\(w/w\)) of yacon dry matter. The carbohydrates accounted for 460 g/kg of syrup obtained from the Hualqui variety and 598 g/kg of syrup for the Crespo variety (Figure 4c,e and Table S3). In the 0.1% CitA Hualqui syrup, free sugars accounted for the most abundant carbohydrates (263 g/kg of syrup), while in the 0.1% CitA Crespo syrup, these accounted for FOS (212 g/kg of syrup) and inulin (165 g/kg of syrup). This composition led to a lower theoretical relative sweetness and theoretical relative glycemic index compared to the Hualqui variety syrup (Table 3). The presence of GalA (5 mol%), Ara (1 mol%), and Gal (1 mol%) in the polymeric material of the syrup also suggested that a portion of yacon pectin polysaccharides becomes solubilized during juice extraction (Table 4). It was also determined that the protein content of yacon syrup is 2.7 g/kg (0.3%), making a negligible contribution to the syrup's caloric value. This protein content was lower than the 10 to 16 g/kg reported for other yacon syrups [21; 44; 45] and the 15 g/kg reported for map syrups [46]. However, it falls within the range typically found in honey [47]. The back extrusion test showed that the resistance provided by the liquid to probe penetration (surface stickiness) was lower for the 0.1% CitA Hualqui syrup than for the Crespo syrup (Table 5). The distance traveled by the probe untilthe liquid no longer offered resistance due to physical separation (stringiness) was also lower for the Hualqui syrup than for the Crespo syrup. This difference can be attributed to the viscosity conferred by inulin [12]. When 0.25% CitA was introduced into yacon juice, the juice pH decreased to a range of about 4 (Table 3). The resulting syrups presented a brown color (Figure S1) and carbohydrate content of 572 g/kg of syrup and 566 g/kg of syrup for the Hualqui and Crespo syrups, respectively (Figure 4c,e and Table S3). Comparing these syrups to the 0.1% CitA syrups, it was observed that the use of 0.25% CitA led to increased Glc content by 14-23%, Fru content by 20-24%, and FOS content by 4-40%. Additionally, it resulted in an increase in the proportion of inulo-type FOS to 13-24% for both varieties (Figure 4d,f). This sug  
Figure 4: Composition of (**a**) Hualqui 5% lemon juice, commercial yacon syrup, and commercial agave syrup and of the (**b**) Hualqui syrups and (**c**) Crespo syrups produced with citric acid (0.1%, 0.25%, 0.25%, and 0.08% ascorbic acid and 0.5%). In (**d–**f**) is represented the proportion of FOS of kesto-type and inulo-type for the corresponding syrup. CitA—citric acid; AA—ascorbic acid; Glc—glucose; Fru—fructose, Suc—sucrose; FOS—fructooligosaccharides. gested a more extensive degradation rate of FOS and inulin than was observed with 0.1% of CitA. In fact, for the Hualqui syrup, the average DP of inulin was 14, lower than that found in the syrup at 0.1% CitA. For the Crespo syrup, the inulin content was reduced by 33%, supported by the lower recovery of polymeric material (100 g/kg, Table 4). The protein content of the yacon syrup decreased to 1.8 g/kg (Table 4), which was 33% lower than in the 0.1% syrup. Given that these syrups only differed on the amount of citric acid added during juice extraction, these differences in protein content can be attributed to protein precipitation in a highly concentrated acid medium, rendering the proteins close to their isoelectric point, at which proteins are less soluble [48]. Compared to 0.1% CitA syrup, the 0.25% CitA syrup had an increase of 10-25% in the theoretical relative sweetness, 7-17% in the relative glycemic index, and 1-24% in the caloric value (Table 3).