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Revista de la Sociedad Química del Perú

Print version ISSN 1810-634X

Rev. Soc. Quím. Perú vol.74 no.1 Lima Jan./mar. 2008


Fibra dietaria en variedades peruanas de frutas, tubérculos, cereales y leguminosas

Dietary fiber in fruits, roots, tubers, cereals and pulses from peruvian cultivars


Glorio, P.*, Repo-Carrasco, R.1, Velezmoro, C.1, Anticona, S.1, Huaranga, R.1, Martínez, P.1, Melgarejo, S.1, Astuhuaman, L.1, Huamán, N.E.1, Icochea, J.C.1, Peña, J.C.1

1 Departamento de Ingeniería de Alimentos, Facultad de Industrias Alimentarias. Universidad Nacional Agraria La Molina. Av La Molina s/n. Lima 12 P.O. Box 12-056 Lima Perú. Fax: 511 349 5764. E-mail:  



Las diferentes variedades de cultivos peruanos llaman la atención debido a sus componentes bioactivos; sin embargo, a pesar de existir datos nutricionales, no se encuentra información disponible sobre fibra dietaria. En este trabajo se utilizó la metodología enzimática gravimétrica AOAC985.29 en la determinación de contenido de fibra dietaria total (TDF), fibra soluble (SF) y fibra insoluble (IF). Entre las frutas estudiadas el mayor contenido de IF fue encontrado en la lúcuma, variedad palo 31,66±0398 %dm. Los contenidos más altos de SF fueron los de chirimoya (6,65±0,215 %dm) cuando son considerados sobre la base de dm peso fresco. En raíces y tubérculos, los valores más altos de TDF fueron los encontrados para la maca (22%dm), seguidos por mashua (14,4%dm) y yacón (14,4 %dm). Entre las papas nativas destacó la variedad Killo acoto (12,5% TDFdm) con IF (8,2±1,147 %dm) y un contenido de SF (4,3±0,636 %dm), el más alto entre las papas nativas. Por el lado de los cereales, la variedad cupi de kañiwa mostró los valores más altos de TDF (27,6%dm). Entre las leguminosas, los frijoles mostraron los valores más altos de TDF, especialmente la variedad de frijol caraota negra.

Palabras clave: fibra dietaria, frutas, nueces, cereales, leguminosas, raíces y tubérculos.  


Peruvian cultivars have called attention due to their bioactive components, but no dietary fiber information was available. This work determines Total Dietary Fiber (TDF), soluble fiber (SF) and insoluble fiber (IF) by AOAC 985.29 methodology. Among the fruits studied the highest IF content was found in lucuma, palo variety (31,66±0398 %dm) and the highest SF contents in chirimoya (6,65±0,215 %dm) when expressed this value over fresh weight. In roots and tubers the highest values of TDF were found in maca (22%dm), followed by mashua (14,4%dm), yacon (14,4 %dm) and potato, yungay variety (14,9 %dm). Killo acoto, native potato,stood out for its high TDF content (12,5%dm) and the highest value of SF (4,3±0,636 %dm) among native potatoes. Between cereals, Kaniwa cupi variety showed the highest values for TDF (27,6%dm). Between pulses, beans showed highest TDF values specially the caraota negra variety.

Key words: dietary fiber, fruits, cereals, pulses, native potatoes, mashua, maca.  


The beneficial aspects of dietary fiber (DF) in humans diet have been studied extensively through the years. Fiber consumption was initially recommended to improve the colonic function, properties mainly attributed to the insoluble fraction. Important physiological effects were attributed to soluble fiber such as normalizing serum lipid levels as cholesterol or attenuating postprandial glucose response. The increased incidence of cardiovascular and chronic diseases has lead to the awareness need for a change on food consumption habits, towards foods with bioactive properties, such as those rich in DF. Nowadays, consumers are demanding DF in their foods. General DF recommendations for adults are in the range of 20 to 35g/day 1.

Dietary fibers, as suberin in tubers, cutin and waxes in leafy vegetables and phenolic esters in lignified tissues of wheat bran have shown beneficial effects which depend not only on the amount of fiber present, but also in the extend of the intact botanical structure conserved. Thus, a consumption of whole foods: fruits, vegetables and grains rich in DF and associated compounds would be more effective than DF extracts or concentrates, in the prevention of chronic diseases.

Typical peruvian roots cultivars, tubers, andean cereals and fruits have called attention due to their bioactive properties. Isothiocyanates and pigments in mashua (Tropaeolum tuberosum Ruiz & Pav.) with reported antibacterial properties against E. pilori; alkaloids and esteroids in maca with fertility and vigor enhancer properties; carotenoids, provitamin A in sweet potato as a source of micronutrients 2; antioxidants in yacon, native potato, mashua, oca and olluco; flavonols, phytoestrogens and phenolic acids in beans 3 and bioactive peptides determined in pulses are reported. In addition, important ingredients for the food industry have been identified in yacon, such as fructans, a source of a low-calorie sweetener 4 and in lucuma, natural pigments and flavor compounds. Among fruits, their content of vitamins and minerals is remarkably. Finally, for the andean cereals the contributions of essential aminoacids, as lysine in amaranth and quinoa protein, is noteworthy 5.

Curiously, we found a lack of information regarding dietary fiber content in peruvian cultivars, even though there is abundance of other nutritional data for peruvian crops. However, there exists DF information for cultivars from other countries of the region. The purpose of this study was to find and provide dietary fiber information to consumers and processors, determining the soluble (SDF), insoluble (IDF) and total dietary fiber (TDF) in those cultivars by using the enzymatic-gravimetric methodology based in AOAC 985.29 6.


Biological material:

Fruits, from different regions of the country, showing sensorial maturity were sampled and purchased from the producers market at Lima - Peru. Those fruits were: papaya (Carica papaya) PauPau from the province of Jaen; Chirimoya (Annona cherimola), cumbe, from the province of Huarochiri; mango (Manguifera indica), criollo, from the department of Piura; lucuma (Pouteria lucuma), seda and palo varieties, from the province of Huaral; pineapple (Ananas comosus), selva variety and banana (Musa paradisiaca), palillo, from the province of Chanchamayo; banana isla and seda varieties, from Lima and Loquat (Eryobotria japonica), from Lima.

The cereals determined by their fiber content were: quinoa (Chenopodium quinoa), Salcedo INIA, blanca de Juli, Kcancolla and Sajama varieties, from the department of Puno and La Molina-89 variety from National Agrarian University in La Molina (UNALM) in Lima; amaranth known in Perú as “kiwicha” (Amaranthus caudatus) centenario variety, was provided by the UNALM cereals program, from Lima; canihua (Chenopodium pallidicaule Heller) cupi, LP-1 and ramis varieties provided by INIA (National Institute for the Agrarian Research) from Puno - Perú.

The leguminous studied were lentils (Lens esculenta), Chick-pea (Cicer arietinum) and Lima beans (Phaseolus lunatus) commercially obtained. Beans (Phaseolus vulgaris L.) caballero, canario, caraota and red kidney varieties provided by the leguminous program from UNALM in Lima.

Roots and tubers were: potato (Solanum tuberosum) yungay and huairo varieties; olluco (Ullucus tuberosus Caldas); aracacha (Arracacia zanthorhiza Bancr); maca or peruvian ginseng (Lepidium meyenii) and mashua (Tropaeolum tuberosum Ruiz & Pav.), all of them commercially obtained at a local market in Lima. Sweet potato (Ipomoea batatas) Jewell, 199047.1, INIA100INIA and Huambachero varieties; kindly provided by INIA (Agricultural research national Institute of Peru). Native potatoes: Solanum tuberosum ssp andigena varieties killo acoto, muro shocco and camusa; Solanum stenotomum varieties calhua rosada, poluya, morar nayra mari; Solanum chauca variety huayro; Solanum goniocalyx variety Garhuash Pashon, yacon (Polymnia sonchifolia Poepp.&Endl) Can Can, Tintin, Bambamarca varieties and oca or New Zealand yam (Oxalis tuberosa)entry GOM 105 were provided by the International Potato Center from Lima. Native potato samples were grown at the province of Huacavelica at 3900 m.a.s.l.

Sample preparation:

About 4 Kg from each sampled cultivar was prepared as followed. Fruits were manually peeled and cut for the selection of the edible portion and for some cases, such as lucuma, pineapple and banana; they were sulfite bleached before freeze-drying. Oleaginous seeds were manually selected, peeled and husk removed, grounded, and finally defatted using a soxhlet extraction apparatus with hexane as solvent. The roots and tubers, samples were freeze-dried with the exception of olluco, maca, aracacha and mashua which were air-dried at 65°C. All samples were grounded till 0,3 mm mesh, before packaging in high density polyethylene bags.

Method of chemical analysis:

Fruits were characterized in terms of acidity, Brix, protein and ash content, following AOAC 7 procedures. For determinations of soluble and insoluble fiber the enzymaticgravimetric method was followed, based on official method from AOAC 985.29 and using a kit from Sigma® (TDF-100 kit). Analytical determinations were performed in the installations of the Physical-Chemical Laboratory of the Food Industry Faculty of the UNALM.


Sample determinations for insoluble dietary fiber (IDF) and soluble dietary fiber (SDF) content were performed by quadruplicates so that protein and ash determinations in the fiber residues could be determined by duplicates following experimental design earlier reported by Marlett and Vollendorf 8; standards deviations were calculated and used for the estimations of the confidence interval (C.I.) for our dietary fiber data. A 95% level of certainty with three degrees of freedom was chosen for selecting the t-value at the statistical “t” table as suggested by Smith 9 when sample numbers are four.


Fractions determined as fiber using this methodology includes hemicelluloses, celluloses, lignin, pectin, nondigestible oligosaccharides, gums and waxes. However, some limitations in the data found may be expected to be due to the methodology adopted because as was earlier reported, there is a variable solubility in alcohol of soluble fiber fractions such as β-glucans, fructans and polydextrose 10; those fractions, may not be completely recovered in the AOAC official methodology 985.29 11; neither may be determined insoluble fractions such as resistant maltodextrin and resistant starch, postulated by Saura-Calixto 12 to be included in the fiber fraction.

Dietary fiber analysis in fruits

Lucuma, a typical peruvian fruit, showed the highest value of total dietary fiber, and the highest dry matter content among the fruit studied, especially for the cultivar known as “seda” (Table 1); lucuma is frequently processed into flour and used by the food industry in icecream, pies and tarts; similar technological applications are reported for banana, palillo variety. Lucuma's dietary fiber was found as mainly insoluble.

Papaya, a fruit of great acceptance among consumers in the region, shows a TDF value, presented in Table 1, higher than data published earlier by Ramulu and Rao 13 (11,7 TDF % dm ),  but comparable, taking into consideration differences in weather, soil and varieties. Also, indian banana TDF values from Ramulu and Rao 13 of 9,5 %dm  were found similar to TDF data for peruvian banana palillo and seda varieties. In general, TDF values for banana in Table 1 were close to those reported by Pak14 (11,03 TDF %dm) for chilean varieties. Chilean chirimoya TDF reported as 14,2 %dm  for Pak was found smaller than TDF data for chirimoya in Table 1.


From all the fruits studied, chirimoya showed the highest amount of SF when it was expressed in terms of g/100g fresh weight (1,91%) followed by banana (Musa spp) palillo variety (1,27% fresh wt.). This information supports the importance of those fruit consumption for assuring health promoting properties reported for soluble fiber. Chirimoya was also found as a fruit with the highest °Brix and the lowest acidity values, followed by banana and lucuma.

                                                                                                                                                                                                                                                                        SF nature in fruits could be affected by intrinsic maturation processes during post-harvest and extrinsic factors, like storage conditions and processing; being frequently observed during maturation, the solution of pectin and loss of galactose from lateral ramifications.

Dietary fiber analysis in roots and tubers

For potatoes, a well known tuber domesticated by the Incas during the VIII century BC, TDF data is shown in Table 2, Solanum Chaucha huayro dietary fiber determinations approached TDF contents earlier reported for Maine potato 8. Also, such results expressed on fresh weight were comparable with red potato data reported by Marlett and Cheung 15. Differences were perceived as resulting, not only due to variety differences, but also, in changes due to processing (cooking and boiling) applied to samples in the references. Potato huayro variety is commonly used in dishes such as stews and sauces where absorption of juices is sought. Therefore the observed lower value in IF could be consistent with the more permeable nature of cells in this potato variety. Solanum tuberosum spp, yungay TDF determinations expressed on fresh weight approached results published for unpeeled baked white potato by Marlett and Cheung 8. However, yungay TDF%dm (hybrid white potato commercially available for all uses) showed a higher value than the one reported for spanish potatoes (11,1 TDF%dm) by Saura-Calixto and others 16. Among the native potato cultivars studied killo acoto showed the highest TDF value with a high insoluble fiber component. Meanwhile, the lowest TDF%dm values in native potatoes were observed for calhua rosada and dm camusa cultivars. The main components of SF have been identified as pectin and hemicellulose and interestingly in our study Killo acoto showed also the highest values of SF among native potatoes, suggesting that this variety may also have greater plasma cholesterolreducing properties since that property was observed in pectin rich food rather than in IF rich ones (except for oats fiber). Finally, it is worth to mention that consumption of 400gfw of this fw cultivar (which is not a rare, for andean populations in Peru during some seasons) would be providing the recommended daily fiber intake stated by the American Dietetic Association.

Yacon, reference data 17 for a Brazilian cultivar, Polymnia edulis, Wedd, indicated TDF 17,88%dm , IF 15,39%dm  and SF 2,43%dm; those are higher values than the one observed in Table 2 for yacon peruvian cultivar. This root was traditionally cultivated for subsistence by samallholders in the Andes. Its fructo-oligosaccharides (FOS) and its organoleptic attributes reported by Herman et al.4 as succulent, tender crunchiness and mildly resinous but pleasantly sweet, have called the attention of scientists and food processors; nowadays, it is being industrialized as a source of syrup, a dietetic sweetener, since FOS are considered indigestible at the small intestine. In Brazil and Japan processing of yacon (such as air-dried tuber slices) offers a low calorie food. This tuber has a high content of oligofructans.

Table 2 reports also TDF values for mashua, olluco and oca roots traditionally cultivated at the Andes by smallholders; but recently, those crops have been enticing people at the cities due to attributed bioactive properties that are being used by traditional medicine and for its characteristic flavor that offer new dimensions in dishes for Chefs under the “novo-andina” cooking trend. Roca et al2 reports for mashua antibacterial (E. pilori) and antioxidant properties, attributed to its isothiocyanates and pigments. The Oxalis tuberosa GOM 105 studied exhibited in Table 2 a TDF % value similar to most of the native potatoes, however, the amounts of SF % for Oxalis tuberosa was the lowest in that table. Olluco, potato and sweet potato are commonly consumed by peruvian population mainly as a source of calories but at the same time they get important quantity of dietary fiber.


Sweet potato cultivars in Table 2 indicated similar SF %dm  values for cultivars Jewell,INIA:199047.1and INIA: 100 which was comparable with some hawaiian varieties earlier reported by Huang and Others 18 however, our Jewell cultivar was different from hawaiians cultivars mainly in the %IFfraction where ours showed highest values. The lowest amount of dietary fiber was observed for huambachero whose TDF content (TDF %fw 1,83) when expressed in fresh weight was comparable with the Satsuma hawaiian variety (TDF %fw 2,27).

Dietary fiber analysis in andean cereals

The andean cereals: quinoa, kaniwa and amaranth, presented high levels of TDF (Table 3). The kaniwa variety cupi had the highest total dietary fiber content. The kaniwa variety LP1 had the highest content of soluble dietary fiber. The high value of total and insoluble dietary fiber of the kaniwa seed is consistent with its higher proportion of pericarp in comparison with the other cereals. The pericarp contains mainly cellulose, lignin and hemicellulose which are part of the insoluble dietary fiber. The values of total dietary fiber in Table 3 are somewhat higher than the values of the rye and much higher than the values of other common cereals, like wheat, oat, barley and maize 19.The content of soluble dietary fiber is similar to the content of this component in rye, about 4 %.


The varieties of quinoa presented had total dietary fiber values between 14,5 and 26,56 %. Some of these values are very similar to wheat 19. The content of SF was also similar to the content of dietary fiber in wheat and in oat. The salcedo variety had the highest content of dietary fiber, similar to the values of kaniwa.

The content of total dietary fiber in amaranth variety centenario presented similar values to barley 19. The content of SF was similar to the quinoa, wheat and oat.

The coefficients of variation (CV) found in insoluble dietary fiber determinations were lower than 10 % in almost all varieties except for quinoa blanca de Juli. The CV values for soluble dietary fiber determinations were higher than 10 % in almost all cereal varieties. Those results are similar to the results of Piccoli da Silva and Santorio 19. According to Prosky et al 20 the method lacks of sensitivity when evaluating samples with low level of soluble dietary fiber.

Dietary fiber analysis in pulses

The content of total dietary fiber in bean varieties in Table 3 was between 15,1 and 25,1 % on dry basis. Among the pulses, beans showed the highest values of TDF, specially the variety caraotas negras. This variety had also the highest proportion of SF (3,12 %). Martin-Cabrejas et al. 21 studied a bean variety carilla, and they found that this variety had 24,5 % TDF of which 7,7 % was soluble and 17,1 % insoluble. Kutos et al. 22 studied the pinto variety and found 23,3 % of total dietary fiber and 3.5 % of soluble dietary fiber. De Alameida et. al 23 found 22,6 % IF and 2,6 % SF for common bean. Perez-Hidalgo et al. 24 studied the white kidney variety (26,3% TDF) and found higher values than those found in this study for canario and caballero variety.


Dietary fiber content information from commonly consumed peruvian cultivars is provided here. This data show a big diversity in those TDF values among cultivars. Those cultivars are utilized in the region as the main source of energy and nutrients. We included in this work as reference materials some cultivars common in other parts of the world for whom there is already fiber content data from other laboratories, However, further work is recommended for improving the estimations of accuracy and precision for these data, such as recovery studies with standards of insoluble and soluble fiber in the matrix of each cultivar studied.

This is one of the fist attempts in providing valuable dietary fiber information for those cultivars. It may be appropriate to suggest for the case of high density foods (80-90% dry matter) cereals and beans and additional future determination of Insoluble fraction content in the processed food since those cultivars are usually subjected to high temperatures during extensive cooking or extrusion before being served, which may change proteins, starch and tannins forming condensed and enzymatic resistant forms which has been reported having physiological importance as well.

Dietary fiber information generated here will help consumers to improve their diet and food processors and nutritionists to explore new food formulations for local and foreign markets. We are not away of the world consumers tendency for searching a better quality of life through an improved diet and due to the high costs of medicine, people is each day more concerned about this matter.


This study was granted with financial support by the CONCYTEC (National Science and Technology Council of Peru). This work was part of the data presented at the Symposium: Functional Foods, Bioactive Compounds and Human Health organized by Cornell University at Ithaca N.Y, between may 22 -27, 2005. We acknowledge the technical assistance of Karina Ccapa



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