Abstract Twenty-two colored-flesh potatoes and three commercial noncolored-flesh varieties – which were all raw as they were microwaved (800 W, 8 min) and fried (180 °C, 5 min) – were characterized in terms of functional, sensory aspects and suitability for use. Twelve genetic samples were more suitable for frying (> 20% dry matter), four for boiling (~15-18% dry matter) and nine for preparing puree or roasting (~18 to 20% dry matter). The total polyphenol content (TPC) of the raw colored-flesh potatoes contained between 1.10 to 3.68 g of gallic acid equivalent kg-1 in fresh weight (FW), which was between two- and three-fold higher than the measured values in noncolored-flesh varieties. The total antioxidant capacity (TAC) was between 1.00 to 4.71 g of Trolox equivalent kg-1 FW, which was also lower in noncolored-flesh potatoes. The cooking process (frying and microwave) did not affect the TPC in most of the genetic samples analyzed, but it reduced the TAC by 40-75% (fried) and 30-90% (microwaved). According to sensory evaluation results, the genetic samples R2, R19, R3 and R5 were suitable for frying, while R16, R21, R9, R15 and R22 were suitable for microwaving. Colored-flesh potatoes are an interesting alternative for consumers due to their greater phytochemical content.

Abstract: The critical value of soil Olsen-P (mg Olsen-P kg-1) is the value of soil Olsen-P above which the probability of crop response to P fertilization is small or null. The aim of the present study was to determine the critical value of soil Olsen-P for potato tuber yield in volcanic soils. The data used in this study were taken from 41 experiments of P fertilization conducted in southern Chile from 1977 to 2015 by the National Potato Center at the Instituto de Investigaciones Agropecuarias (INIA). To identify the critical values of soil Olsen-P, relationships between relative yields and initial soil P-Olsen were assessed using three models (linear-plateau, boundary and Mitscherlich function). Across experiments, the average fresh tuber yield was 41.9 Mg ha-1 and varied between 4 and 89 Mg ha-1. Fresh tuber yield decreased up to 92% by P deficiency; however, yield reduction was concentrated between 20 and 40%. The critical Olsen P values determined were 41, 33 and 11 mg Olsen-P kg-1 obtained (P < 0.01) with linear-plateau, boundary function and Mitscherlich function, respectively. However, linear-plateau and Mitscherlich functions showed lower coefficient of determinations (R2 = 0.23 - 0.31) than the boundary function (R2 = 0.97). Therefore, we suggest that the critical Olsen-P value of 33 mg P kg-1 determined with the boundary function is more appropriate for potato growers than the critical value determined with the other models. This information will be valuable for optimizing strategies for P fertilizer management in potato production systems aimed at achieving optimal crop yield and minimizing potential environmental risk.