Jesus Arcos’s research while affiliated with Instituto Nacional de Innovación Agraria and other places

Variables and interaction effects affecting the mineral concentration of Andean bitter potatoes converted into so-called white chuño are unknown. We report on the effect of three contrasting production environments (E) on the dry matter (DM), zinc, iron, calcium, potassium, magnesium, phosphorus and sodium concentration of four potato native bitter genotypes (G) processed (P) into two different 'types' of white chuño. The DM content and iron, calcium, magnesium and sodium concentration of white chuño are significantly dependent on E, G, P, and E × G × P interaction (predominantly at P < 0.01). In particular, the DM content and calcium concentration are influenced by all variables and possible interaction effects. The zinc and potassium concentration are not significantly dependent on E × G, G × P or E × G × P interaction effects, while the phosphorus concentration is not significantly affected by the G × P or E × G × P interaction effect. Zinc, phosphorus and magnesium concentrations decrease in the ranges of 48.3-81.5%, 61.2-73.0% and 62.0-89.7% respectively. The decrease in potassium is particularly severe, with 122- to 330-fold losses. Iron and calcium increase by 11.2-45.6% and 74.5-714.9% respectively. E, G, P, and various interaction effects influence the mineral concentration of traditionally processed tubers. We speculate that mineral losses are caused by leaching, while increases of iron and calcium are a likely result of absorption.

Traditional Processing of Black and White Chuño in the Peruvian Andes: Regional Variants and Effect on the Mineral Content of Native Potato Cultivars. Farmers in the high Andes of central to southern Peru and Bolivia typically freeze-dry potatoes to obtain chuño. Processing of so-called black chuño follows tending, treading, freezing, and drying. The making of white chuño is generally more complex and involves exposure of tubers to water. Regional variants exist for each of these processes, yet their influence on the nutritional composition of native potato cultivars is little known. Tubers belonging to four distinct cultivars and produced in a replicated trial under uniform conditions were processed into four types of chuño following standard traditional procedures (farmer-managed). These regional variants were documented, and the dry matter, iron, zinc, calcium, potassium, phosphorus, magnesium, and sodium content of the four resulting different types of boiled chuño determined at the International Potato Center's Quality and Nutrition Laboratory (Lima, Peru). Content values were compared with those of boiled (unprocessed) tubers from the same experiment. Regional variants of processing are to a large extent determined by tradition, environmental condition, and market demand. The zinc, potassium, phosphorus, and magnesium content of all types of chuño decreases in comparison with unprocessed tubers. Concentrations of these same minerals decrease more drastically for white as compared to black chuño. The effect of the four regional variants of freeze-drying on the dry matter, iron, calcium, and sodium content of chuño differs by process and/or cultivar.

The potato in its Andean center of origin is commonly freeze-dried to assure long-term storability and consequent availability of food during periods of scarcity. The final product is known as chuño. Depending on the process and cultivars used, different kinds of chuño are prepared: white chuño (moraya, tunta) and black chuño. This paper explores the nutritional value of chuño using data from research in the Peruvian Andes. The paper specifically investigates the effect of regionally different processes on the mineral content of chuño: Zn, Fe, Ca, K, P, Mg and Na. First, the effect of 4 processes (P), resulting in 2 types of white and black chuño respectively, for 4 cultivars (C) belonging to distinct botanical species (P*C interaction). Second, the influence of locality, cultivar and process on nutrient concentrations (L*C*P interaction). Specifically, the effect of 3 contrasting growing environments on the mineral content of 4 cultivars processed into 2 types of white chuño. Results of the first experiment show that the mineral content of chuño, independent of the mineral analyzed, is significantly influenced by P*C interaction. Results of the second experiment show that particularly the dry matter, Ca, Mg and Na content of white chuño is significantly affected by L*C*P interaction. The zinc, potassium, phosphorus and magnesium content of all 'types' of chuño decreases in comparison with boiled (unprocessed) tubers. White chuño generally contains stable to high iron and high calcium concentrations.