Chemical constituents of fresh‐cut potato as affected by cultivar, age, storage, and cooking

Abstract

Certain changes in phenolics and sugars can occur during the storage of potatoes, where particularly amounts of sugars represent the critical factor as they are involved in potentially harmful acrylamide (AA) formation during frying. This research investigates the impact of cultivars (Birgit and Lady Claire), tuber's age (1, 5, and 9 months), and storage duration (1, 5, and 8 days at 10 • C) on the content of phenolics and sugars in raw, boiled, and fried fresh-cut potato (FCP). The influence of these factors on the formation of AA in fried FCP was also assessed. Significant differences in phenolics and sugars were observed between cultivars (cv. Birgit contained 5.77 mg of phenolics 100 g -1 of dry weight (DW) and 1.75 g of sugars 100 g -1 DW, while cv. Lady Claire contained 10.13 mg of phenolics 100 g -1 DW and 0.65 g of sugars 100 g -1 DW). The content of phenolics significantly decreased, while sugars increased during tubers' aging. FCP storage time had no significant influence on the content of phenolics and sugars. The phenolics and sugars were the highest in the raw samples and the lowest in the boiled ones. Although the AA level in fried samples was significantly influenced by cultivar (Birgit > Lady Claire) and it increased with FCP storage time, it was below European Food Safety Authority (EFSA) regulation's approved maximum value (750 µg kg -1 FW) in both cultivars. Therefore, cvs. Birgit and Lady Claire could be considered as promising FCP cultivars and for frying purposes. Practical Application: The results of this research reveal that quantitative changes of chemical constituents occurring during storage and cooking of freshcut slices of potato cultivars Birgit and Lady Claire are not a concern. This is of particular importance to fresh-cut producers and customers. Phenolics were reduced during storage, but they were still present in all cooked samples independently of the cooking method. The analysis of sugars showed that tubers as old as 9 months could be used for fresh-cut potato processing, providing safe frying without critical levels of acrylamide.

Effect of UV-C Irradiation, Storage and Subsequent Cooking on Chemical Constituents of Fresh-Cut Potatoes

“…Grand mean (GM) value of chlorogenic acid content was 9.67 mg 100 g −1 DW, which is slightly higher when compared to the chlorogenic acid GM of the same potato variety in the 2017 harvest (7.46 mg 100 g −1 DW) [28]. Statistical analysis did not show a significant effect of UV-C treatment on the content of chlorogenic acid, although a slight decrease with increasing of UV-C dose can be observed.…”

“…Extraction of phenolics was conducted as previously described by Dite Hunjek et al [28]. Briefly, phenolics from homogenized freeze-dried samples (0.5 g) were extracted with 5 mL of 80% methanol with 1% formic acid (v/v), using ultrasonic bath (Elmasonic 40H, Elma, Germany) for 30 min at 50 • C. After centrifugation at 3000 rpm/10 min (Hettich ® Rotofix 32a, Tuttlingen, Germany), the procedure was repeated by adding 5 mL of extraction solvent to precipitate.…”

“…The extraction of sugars was performed according to the method described by Dite Hunjek et al [28]. The 4 mL of 80% methanol (v/v) was added into 0.4 g of the ground freeze-dried sample.…”

“…(Nacalai Tesque, INC., Kyoto, Japan) column. The chromatographic conditions were as described by Dite Hunjek et al [28]: mobile phase (80% acetonitrile, v/v) was in isocratic elution mode at flow rate of 1.3 mL min −1 , injection volume was 10 µL, and the column temperature was set at 45 • C. Identification and quantification of sugars was conducted by comparing retention times and peak areas with the one obtained from standard solutions. Standard solutions were prepared in 80% ethanol (v/v) and a fixed concentration of each sugar standard was used for quantification.…”

“…The UPLC MS 2 analysis of acrylamide was performed as previously described by Dite Hunjek et al [28] by Agilent UPLC system (Section 2.6.2). A Hypercarb TM col-umn (5 µm, 50 mm × 2.1 mm) with a guard column (5 µm, 10 mm × 2 mm) (Thermo Hypersil-Keystone, Bellefonte, PA, USA) was used for the separation, column temperature was set at 22 • C, injection volume was 10 µL, and flow rate 0.7 mL min −1 .…”