Distribution of glycoalkaloids in potato plants and commercial potato products

Abstract

As part of a program to control the biosynthesis of Solanum glycoalkaloids in potatoes, we used a modified extraction-HPLC assay to measure the -chaconine and -solanine content of commercial and new potato varieties, different parts of the potato plant, and commercial potato products. The improved assay was accomplished by extracting, precipitating, and filtering the hot methanol extract through a 0.45-µ membrane before HPLC analysis. Recoveries of spiked samples ranged from 89 to 95%. The combined -chaconine and -solanine contents of different parts of the new NDA 1725 potato cultivar (in milligrams per 100 g of fresh weight) were as follows: tubers, 14.7; main stems, 32.0; small stems, 45.6; roots, 86; leaves, 145; and sprouts, 997. The -chaconine content of several other potato cultivare ranged from 1.17 to 13.5 mg/100 g of fresh weight and the corresponding a-solanine content from 0.58 to 5.9 mg/100 g of fresh weight. The corresponding values for potato berries were 22.1 and 15.9 mg/100 g of fresh weight, respectively. The total glycoalkaloid content determined by titration with bromophenol blue was 12-30% greater than the sum of -chaconine and a-solanine determined by HPLC. The extraction-HPLC method was adapted to measure the glycoalkaloids in freeze-dried french fries (0.08-0.84 mg/100 g of product), skins (3.1-20.3 mg/100 g of product), potato chips (2.4-10.9 mg/100 g of product), and potato pancake powders (4.S-6.5 mg/100 g of product). The presence of the two glycoalkaloids in commercial foods was also confirmed by thin-layer chromatography. The possible significance of these findings to food safety and plant physiology is discussed.

Cooking influence on physico-chemical fruit characteristics of eggplant (Solanum melongena L.)

“…Glycoalkaloids content (Table 1) generally was quite stable after cooking, in accordance with previous data reported on potato (Friedman & Si Dao, 1992). This is demonstrated by the general trend of total glycoalkaloids (Table 1) that showed an increase after grilling and a decrease after boiling, caused, as previously stated, by a water loss (concentration) and by a leaching (dilution), respectively.…”

The influence of French fries processing on the glycoalkaloid content in coloured-fleshed potatoes

“…nema et al [23] reported that Tga content in frozen peels of different edible varieties ranged from 6.5 to 12.1 mg 100 g −1 f.w. Many authors, Friedman and Dao [6], Wünsch and Munzert [39], Friedman [5], and Friedman and levin [7], reported that most Tga in the tuber are accumulated in the peel, especially in the area of eyes, whereas the distribution of Tga in a tuber differs among varieties. Some researchers, Wünsch and Munzert [39], Friedman and McDonald [8], Pęksa et al [26], Friedman [8], Tajner-Czopek et al [37] and Ostry et al [25], think that there may occur significant differences in Tga content among of the same varieties.…”

“…The ratio of α-solanine to α-chaconine varies between varieties, although α-chaconine usually occurs in distinctly higher concentration than α-solanine [6,8,16,23,30,37]. The scientific literature most frequently has provided data on the ratio of α-solanine to α-chaconine in lightfleshed varieties.…”

Metabolite Measurements

“…A number of different columns and elution protocols for many different compounds or compound classes have been developed and successfully applied for metabolic studies. Methods exist for small sugar analysis [15], amino acids [41], nucleotides [57,68], flavonoids [59], volatiles [6], or alkaloids [30].…”