Yacon (Smallanthus sonchifolius [Poepp. & Endl.] H. Robinson) is an under-exploited native root crop of the Andes, which stores oligofructans (fructo-oligosaccharides, FOS) as its main component of dry matter (DM). FOS are of increasing economic interest because of their low caloric value in human diets and bifidogenic benefits on colon health. Two on-farm experiments were conducted to: (i) determine the effect of shaded, short-term storage at 1990 and 2930 m a.s.l. in the Andean highlands; and (ii) address the effects of a traditional sunlight exposure ('sunning') on the carbohydrate composition in the DM of tuberous yacon roots. After a 6-day shade storage FOS concentrations were smaller at the lower (36-48% of DM) than at the higher altitude (39-58% of DM). After 12 days FOS concentrations were nearly equal at both sites (27-39% of DM). The concentration of free sugars (fructose, glucose, sucrose) increased accordingly from 29-34 to 48-52%. During the 6-day sunning experiment FOS concentrations decreased from 50-62 to 29-44% and free sugars increased from 29-34 to 45-51%. The results indicate that partial hydrolysis of oligofructans starts shortly after harvest. Storage in highland environments should wherever possible exploit the cooler temperatures at higher altitudes. Sunning of yacon's tuberous roots effectively reduces much of the roots' water content, in this experiment 40%, and thus allows energy to be saved if yacon is processed into dehydrated products. #

Colour type has to be considered in maca production, as colour associates with variations in concentrations of distinct bioactive metabolites. Leaves may be interesting for animal nutrition purposes as they contain essentially the same secondary metabolites as the hypocotyls but in clearly lower concentrations.

Andean potatoes are gaining popularity not only for their appealing colors and culinary uses but also for their potential higher content of polyphenolic compounds. The objective of this study was to identify potato varieties with increased phenolic content. This was achieved through characterization and quantitation of the phenolic composition in 20 varieties of native Andean potatoes from 4 different Solanum species with different colors. Major quantitative and qualitative differences among evaluated samples were more dependent on the coloration of the extracted sample rather than on the species. The most predominant anthocyanidins were petunidin-3-coumaroylrutinoside-5-glucoside and pelargonidin-3-coumaroylrutinoside-5-glucoside in purple and red potato extracts, respectively, while chlorogenic acid and its isomers were the main phenolic compund (43% of the total phenolic content). Our study suggested that the appropriate selection of native potatoes could provide new sources of polyphenolics with health promoting properties and natural pigments with increased stability for food applications.

Background: Yacon is a root crop which contains high amounts of fructooligosaccharides (FOS). The aim of this study was to investigate the effects of yacon syrup on colon transit time in healthy volunteers. Methods: In a placebo-controlled, double-blind study yacon was administered to 16 healthy individuals (8 males, 8 females) in a dose of 20 g daily (equal to 6.4 g FOS) in a 2-week crossover design. Each period was interrupted by a 2-week wash-out phase. Transit time was assessed by a radio-opaque marker technique. Results: Transit time (mean ± SEM) through the gastrointestinal tract was significantly decreased from 59.7 ± 4.3 to 38.4 ± 4.2 h (p < 0.001). Yacon was well tolerated with an excellent side effect profile. Bloating is not an uncommon side effect observed with FOS, but bloating-related disturbances were not significantly more often reported with yacon compared to placebo. Stool frequency increased from 1.1 ± 0.1 to 1.3 ± 0.2 times per day and the consistency showed a tendency for softer stools as assessed by a numerical depicted stool protocol. Neither parameter did, however, reach statistical significance. Conclusion: Yacon markedly accelerates colonic transit in healthy individuals. Further studies are needed in constipated patients to confirm these preliminary data. Due to the low caloric content of yacon, the root could be a useful treatment in constipated diabetics or obese patients.

A gronomy J our n al • Volu me 102 , I s sue 2 • 2 010 431 ABSTRACT Maca (Lepidium meyenii Walpers) hypocotyls are reported to have a favorable biological activity in man. Th e presumed bioactive constituents seem to vary among maca hypocotyl color types, but the residual variation is large. Th is study tested the hypothesis that, apart from color types, environmental factors have a distinct infl uence on the concentration of characteristic secondary metabolites in maca. In a fi eld experiment at 4100 m altitude (Peru), maca of four hypocotyl color types was evaluated at two sites with diff erent soil types. At each site, experimental areas were either never cultivated or cultivated with maca 2 to 3 yr ago followed by a fallow period. Applying four color replicates per site and area resulted in 64 plots (100 plants plot -1 ). Especially color type largely infl uenced concentrations of macaene, macamides, β-sitosterol, campesterol, and glucosinolates. Site (also clearly aff ecting growth yield) was weaker in eff ect on these metabolites but still signifi cantly infl uenced concentrations of some constituents, while the eff ect of cultivation history was widely absent. Macaene, macamides, and β-sitosterol were negatively correlated with glucosinolates. Th is shows that environmental conditions and color type have to be considered in producing maca with high concentrations of distinct bioactive metabolites.