# Utilization of Yacon Damaged Roots as a Source of FOS-Enriched Sweet-Tasting Syrup
## 3 Results and Discussion
### Syrup Production
#### 3.2.2 Effect of Ascorbic Concentration on Syrup Properties  
The incorporation of 0.08% ascorbic acid alongside 0.25% CitA decreased the yacon juice pH to around 4.3, with values falling within the range achieved by using only 0.25% CitA (Table 3). The obtained syrups presented 70-75 \({}^{\circ}\)Brix and contained 57-78% of yacon material. The syrups produced using the Hualqui and Crespo damaged roots presented a carbohydrate content of 377 g/kg of syrup and 531 g/kg of syrup, respectively (Figure 4b,c and Table S3). In comparison to the 0.25% CitA syrup, the addition of 0.08% ascorbic acid decreased Glc content by 3-9% and Fru content by 8-21%. This effect could be attributed to the thermal degradation, occurring between 70 and 90 \({}^{\circ}\)C, of ascorbic acid through a non-enzymatic browning reaction with the available carbonyl groups of sugars [53]. Furthermore, the capacity of Fru to rearrange as a furanose makes it more reactive than pyranoses as Glc, in particular when in the presence of citric acid [54]. In the Hualqui syrups, a significant decrease in FOS content of 83% was observed, suggesting that oligosaccharides achorides rich in Fru might also react with ascorbic acid. Such an effect was not as pronounced in the  
Figure 5: Proportion of total Fru and Glc units (mol/kg) present as free sugar and as part of FOS and inulin found in the syrups made from (**a**) Hualqui and (**b**) Crespo varieties. CitA—citric acid; AA—ascorbic acid; Glc—glucose; Fru—fructose.  
Crespo syrups, possibly due to a balance between the reaction rate of FOS with ascorbic acid and their formation by inulin depolymerization. As observed in the CitA experiments, the newly formed FOS were predominantly of the inulo-type, increasing to a proportion of 27-36% compared to the initial yacon raw material (Figure 4e,f). However, when following syrup production using reduced pressure via rotary evaporation, which lowers the boiling point of water, the amount of inulo-type FOS formed only increased to 9% of a total of 263 g/kg (Table S3). Furthermore, the Glc (79 g/kg) and Fru (172 g/kg) content was lower due to a reduced rate of hydrolysis of inulin, resulting in a theoretical relative sweetness lower than the syrup made at atmospheric pressure (Table 3). However, the decrease in processing temperatures from 90 \({}^{\circ}\)C to 70 \({}^{\circ}\)C has been reported to limit ascorbic acid degradation [54], as well as the formation of bitter compounds [55] that likely mask the sweetness estimated for the syrup produced at atmospheric pressure. The syrup produced under reduced pressure exhibited a caloric value coherent with the 196-222 kcal/100 g reported for yacon syrups produced under vacuum pressures and was reported to be composed of 140 g of Glc/kg, 229 g of Fru/kg, and 307 g of FOS/kg of syrup [44,45]. Therefore, in an industrial context, the use of 0.08% ascorbic acid negatively impacts the syrup's sweetness as it reacts with sugars. In this context, ascorbic acid addition as an antioxidant should be limited to assure the production of FOS-rich syrup with high sweetening power.