## 4 Discussion
However, in transgenic tomato fruits [31] and tobacco plants [32], where the biosynthesis of lignin was down-regulated, higher levels of neo-CGA, crypto-CGA, and CGA were detected, indicating that CGA and its isomers are involved in lignin biosynthesis. Regarding the other phenolic compounds identified (FA, \(p\)-CA, and 3,5-diCQA), only mild changes on their concentration were detected during storage of the whole and wounded tissue. For instance, FA and \(p\)-CA were not detected in the CBS sample, whereas their highest content of 6.97 mg/kg and 9.20 mg/kg were detected in pie-cut and whole potatoes stored at 20 \({}^{\circ}\)C for 168 h and 144 h, respectively (data not shown). Likewise, only a mild increase in 3,5-diCQA content was observed in whole carrots stored for 144 h at 20 \({}^{\circ}\)C. The low accumulation of FA and \(p\)-CA in the wounded tissue supports previous findings indicating that their biosynthesis and utilization rates (for lignin and suberin production) are similar, giving only a slight positive balance on the accumulation of both lignin and suberin precursors [8; 33]. Finally, in accordance with previous reports, the low accumulation of 3,5-diCQA detected in the wounded tissue and the slight, but significant, increase in the whole tissue, support the previous hypothesis that this compound is not involved as a precursor of lignin and suberin [8]. Practical Approaches for the Use of Potatoes as Biofactories of CGA Isomers and Its Potential Use as Raw Material or in the Production of Functional Foods and Ingredients  
Recently, it was proposed that fruits and vegetables with an increased content of bioactive compounds, induced by the application of postharvest treatments, could be used as raw material to produce food and beverages with enhanced nutraceutical value [34; 35; 36; 37; 38; 39; 40]. Following this approach, products such as carrot juice [37] and purce [38] with an enhanced content of CGA have been produced. In the specific case of the carrot purce, it was tested on animal subjects to validate its pharmacological effect to enhance the cognitive abilities and neural development of rats. Moreover, food ingredients using the raw material of stressed carrot tissue with enhanced levels of CGA have been developed and added to highly consumed foods such as tortillas [35] and sausages [36]. In this context, potatoes containing higher levels of CGA due to wounding stress could also be used as ingredients to produce functional foods. Based on previous reports and the results obtained in the present study, Figure 2 presents different postharvest wounding stress and storage conditions that could be applied in potatoes to enhance the accumulation of specific CGA isomers. Figure 2: Postharvest wounding stress and storage temperature conditions to trigger the accumulation of specific chlorogenic acid (CGA) isomers in potatoes. The tissue with an increased content of CGAs could be used as raw material to produce functional foods or dietary supplements. Potatoes with increased levels of CGAs could be used to produce value-added products such as functional foods or dietary supplements. In accordance with the results obtained herein, if potatoes with a high content of CGA are desirable, pie-cut potatoes should be stored for 120 h at 20 \({}^{\circ}\)C, whereas if an enhanced concentration of crypto-CGA is expected, the tissue should be stored for 144 h at 20 \({}^{\circ}\)C, and to trigger the accumulation of neo-CGA, potato pie-cuts should be stored for 120 h at 10 \({}^{\circ}\)C. These raw materials with an increased content of CGA isomers could be used for the manufacturing of potato products fortified with CGA isomers. Examples of possible processed products include potato puree, or fried potatoes. Interestingly, regarding potato fries, it is likely that if stressed potatoes are used for their production, a lower content of acrylamide would be produced during frying, since asparagine content (a precursor for acrylamide formation) is highly decreased at the storage conditions of wounded potatoes [24].