Bioactive Compounds in Potato Tubers: Effects of Farming System, Cooking Method, and Flesh Color

Abstract

We investigated the effect of cultivation system (conventional or organic), cooking method, and flesh color on the contents of ascorbic acid (AA) and total phenolics (TPs), and on total antioxidant activity (Trolox equivalents, TE) in Solanum tuberosum (potato) tubers. The research material, consisting of 4 potato cultivars, was grown in experimental fields, using organic and conventional systems, at the experimental station in 2012 and 2013. The analysis showed that organically grown potatoes with creamy, light yellow, and yellow flesh had significantly higher TPs than did potatoes grown conventionally. Flesh color and cooking method also affected AA. The greatest losses of AA occurred in yellow-fleshed potatoes grown conventionally and cooked in the microwave; such losses were not observed in potatoes grown organically. A dry cooking method (baking in a microwave) increased the TP contents in potatoes by about 30%, regardless of the flesh color and the production system. TE was significantly higher in organically grown potatoes (raw and cooked in a steamer) than in conventionally grown potatoes. TE and AA contents showed a significant positive correlation, but only in potatoes from the organic system [R2 = 0.686]. By contrast, the positive correlation between TE and TPs was observed regardless of the production system. Therefore, we have identified the effects of farming system, cooking method, and flesh color on the contents of bioactive compounds in potato tubers.

Effect of Organic Potato Farming on Human and Environmental Health and Benefits from New Plant Breeding Techniques. Is It Only a Matter of Public Acceptance?

“…Protein profiling also changes, with organic tuber proteome enriched in stress-related proteins [14], even though other authors, such as Brazinskene et al [15], are not in agreement with these findings. As reported by Brandt et al [16], the plants managed by organic practices have necessarily to cope more frequently with pathogens, and accordingly accumulate more defense-related compounds (such as phenylpropanoids [9,10,12,17]) than conventionally produced tubers. Some phenolics are associated with health-promoting effects, mainly related to their antioxidant activity: chlorogenic acid, carotenoids, and anthocyanins have been reported to protect against degenerative diseases, cancer, heart diseases, hypertension, and viral and bacterial diseases [18].…”

“…Up to date, only few studies focused on organic potatoes and most of them investigated target beneficial (vitamin C, flavonoids, vitamin B1, phenolics) and harmful compounds (heavy metals, glycoalkaloids, nitrates, residues of pesticides), organoleptic properties, and agronomic parameters (yield, tuber size, germination of tubers, starch content). Surprisingly, a high vitamin C content, typical of most organic food, is not always confirmed in organic tubers [7,[9][10][11][12] that, indeed, frequently show high content of vitamin B1 [11]. Organic restrictions on fertilization causes a reduced nitrogen availability, resulting in a lower N content in organic tubers, that could strongly influence the vitamin C content, together with the concentration of nitrate and total proteins [6,7] and the content and composition in free amino acids.…”

Phytochemicals in Leaves and Roots of Selected Kenyan Orange Fleshed Sweet Potato (OFSP) Varieties

“…It is, however, noted that antioxidant activity does not depend solely on coloured compounds analyzed in this study since the white fleshed roots with undetectable levels of phenolics and flavonoids had considerable amounts of antioxidant activity. e sweet potato leaves with high amounts of phytochemicals indicated quite high levels of free radical scavenging activity, the highest correlation (푟 = 0.975, 푝 < 0.0001) being displayed by total flavonoids (Table 4) showing the contribution of these phytochemicals to antioxidant activity [32,39] as indicated by significant positive correlattion. High levels of phenolics, flavonoids, vitamin C and antioxidant properties in sweet potatoes, and especially, the leaves can therefore be exploited to prepare different food mixes with high antixidant properties useful in preventing and controlling some lifestyle diseases.…”

“…Leaves of all sweet potato varieties may not be suitable for frequent human consumption especially for those with kidney stones problems due to the high levels of oxalates exhibited in these varieties [51]. Oxalates bind calcium and magnesium and interfere with their absorption and metabolism hence the need to limit compared to Yildirim et al [38] who reported a range of 23.7-38.6 mg/100 g. Compared to potato tubers [39,40], the roots vitamin C content in tested sweet potato varieties was lower. e leaves exhibited high vitamic C content that are comparable to conventional fruits and leafy vegetables that range between 2 and 500 mg/100 g dry weight [41].…”

Effect of Different Methods of Thermal Treatment on Starch and Bioactive Compounds of Potato

“…This group of compounds includes, among the others, phenolic acids (chlorogenic, caffeic, coumaric, and vanillic). In potatoes with yellow, purple-and red-coloured flesh, flavonoids, such as catechin, rutin and anthocyanins as well as carotenoids (carotene, lutein, neoxanthin) are found [10,11]. Most bioactive compounds undergo changes during the thermal treatment of potatoes, and these changes are determined by the process time and temperature as well as the presence of water or steam [2,5,[10][11][12].…”