abstracts - INCDCSZ Brasov

Reducing sugars increased especially in the cultivar Bintje (tubers with severe symptoms),
whereas the other cultivars remained most stable. Sucrose concentration increased significantly in
tubers with severe symptoms (gummy-like texture). Bintje had the highest sucrose level, followed by
Saturna and Hermes. They all exceeded levels above 1000 mg sucrose/100 g FW. Lady Claire had the
lowest sucrose concentration in stolbur affected tubers (Table 2).
Tab. 2: Sucrose content [mg/100 g FW] of the three quality classes of the investigated cultivars
Object Bintje Agria Lady Claire Pirol Saturna Hermes
Average 692 ± 441 500 ± 346 410 ± 204 487 ± 256 691 ± 413 757 ± 419
Healthy
tubers
328 ± 3.69 b 234 ± 58.6 b 297 ± 15.2 b 311 ± 25.9 b 356 ± 54.3 b 367 ± 56.6 a
Minor
symptoms
516 ± 50.4 b 333 ± 83.4 b 292 ± 33.4 b 352 ± 87.8 b 544 ± 78.1 b 722 ±452 a
Severe
symptoms
1,233 ± 320 a 932 ± 220 a 642 ± 209 a 798 ± 188 a 1,174 ± 351 a 1,182 ± 53.7 a
Different letters indicate a statistically significant difference (P > 0.05) (Student-Newman-Keuls-Test)
Next to the absolute concentration of constituents also the distribution within tubers was investigated.
Tubers with severe stolbur symptoms had a higher dry matter concentration than tubers
with minor symptoms. In both cases, the core region had a lower dry matter concentration than bud or
stem end. Glucose and fructose concentration was highest in the stem end region, whereas sucrose
concentration was uniform over the different tuber regions (Tab. 3).
Tab. 3: Dry matter and low-molecular weight carbohydrates in potato tubers with stolbur symptoms,
separated into sections.
Stolbur Section DM [%] Glucose
[mg/100 g FW]
Minor
symptoms
Severe
symptoms
596
Fructose
[mg/100 g FW]
Sucrose
[mg/100 g FW]
Whole tuber 25.9 52 19 1,011
Bud end 26.1 206 69 1,165
Core 22.5 21 12 972
Stem end 26.2 110 20 871
Whole tuber 30.9 51 17 2,550
Bud end 33.6 252 149 2,325
Core 28.2 38 17 2,451
Stem end 34.6 89 13 2,485
Conclusion
Potatoes with stolbur symptoms had significantly higher sucrose levels than the control, equally
distributed within tubers. These tubers are not qualified for any processing. It will be a challenge to
develop tools to separate infected tubers from single lots. This seems to be the only way to prevent a
non-acceptance by the factories.