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Eve Emshwiller - One of the best experts on this subject based on the ideXlab platform.
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genetic basis for folk classification of oca Oxalis tuberosa molina oxalidaceae implications for research and conservation of clonally propagated crops
Genetic Resources and Crop Evolution, 2017Co-Authors: Lauren J Moscoe, Raúl Blas, Daniel Huaman Masi, Modesto Huaman Masi, Eve EmshwillerAbstract:Clonally propagated crops exhibit great diversity and are integral components of global and regional food systems. At the same time, little is known about the mechanisms that generate diversity within clonal crop species, and this diversity is increasingly threatened by economic, environmental, and social change. Research addressing the genetic basis for folk classification of clonal crops can address both of these challenges. Here, we carry out such research through a case study of the Andean tuber crop, oca (Oxalis tuberosa Molina). We employ ethnobotanical and molecular genetic methods to assess the congruence in partitioning of 216 oca accessions with respect to 26 folk taxa and with respect to 31 genetic clones. We find that the greatest number of folk taxa (11) correspond to single, unique genetic clones, but we also identify two instances of single folk taxa comprising multiple genetic clones and two instances of multiple folk taxa comprising single, shared genetic clones. We discuss the potential roles of different diversity-generating mechanisms, such as somaclonal variation and sexual reproduction, underlying these varied forms of congruence in order to inspire more directed research on this topic. We also discuss the implications of our findings on in situ and ex situ conservation work, in which practitioners often approximate crop genetic diversity by counting folk taxa. Ultimately, we argue that efforts to understand and conserve clonal crop diversity will be most effective when both folk classification and its genetic basis are considered together.
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Genetic basis for folk classification of oca (Oxalis tuberosa Molina; Oxalidaceae): implications for research and conservation of clonally propagated crops
Genetic Resources and Crop Evolution, 2017Co-Authors: Lauren J Moscoe, Raúl Blas, Daniel Huamán Masi, Modesto Huamán Masi, Eve EmshwillerAbstract:Los cultivos propagados por clones muestran una gran diversidad y son componentes integrales de los sistemas alimentarios globales y regionales. Al mismo tiempo, se sabe poco sobre los mecanismos que generan la diversidad dentro de las especies de los cultivos clonales, y la amenaza a esta diversidad aumenta cada vez más por los cambios económicos, medioambientales y sociales. Ambos desafíos pueden abordarse con las investigaciones sobre la base genética de la clasificación campesina de los cultivos clonales. Por ello, se llevó a cabo esta investigación por medio de un estudio de caso del tubérculo andino, oca ( Oxalis tuberosa Molina). Se empleó métodos etnobotánicos y genéticos moleculares para evaluar la congruencia de la clasificación de 216 entradas de oca con respeto a 26 taxones campesinos y a 31 clones genéticos. Se encontró que el número más alto de los taxones campesinos (11) corresponde a clones genéticos individuales y únicos, pero también se identificó dos casos en que los taxones campesinos individuales constan de múltiples clones genéticos y dos casos en que múltiples taxones campesinos constan de clones genéticos únicos y compartidos. Se discuten los roles potenciales de los distintos mecanismos de generación de la diversidad que subyacen estas formas variadas de la congruencia, como la variación somaclonal y la reproducción sexual, para incentivar más la investigación dirigida en este tema. También se discuten de las implicaciones de nuestros resultados en el los trabajos de conservación in situ y ex situ, en que es común aproximar la diversidad genética de cultivos por medio del conteo de los taxones campesinos. Por último, argumentamos que los esfuerzos por entender y conservar la diversidad de los cultivos clonales tendrán más éxito cuando se tome en cuenta la clasificación campesina junto con su base genética. Clonally propagated crops exhibit great diversity and are integral components of global and regional food systems. At the same time, little is known about the mechanisms that generate diversity within clonal crop species, and this diversity is increasingly threatened by economic, environmental, and social change. Research addressing the genetic basis for folk classification of clonal crops can address both of these challenges. Here, we carry out such research through a case study of the Andean tuber crop, oca ( Oxalis tuberosa Molina). We employ ethnobotanical and molecular genetic methods to assess the congruence in partitioning of 216 oca accessions with respect to 26 folk taxa and with respect to 31 genetic clones. We find that the greatest number of folk taxa (11) correspond to single, unique genetic clones, but we also identify two instances of single folk taxa comprising multiple genetic clones and two instances of multiple folk taxa comprising single, shared genetic clones. We discuss the potential roles of different diversity-generating mechanisms, such as somaclonal variation and sexual reproduction, underlying these varied forms of congruence in order to inspire more directed research on this topic. We also discuss the implications of our findings on in situ and ex situ conservation work, in which practitioners often approximate crop genetic diversity by counting folk taxa. Ultimately, we argue that efforts to understand and conserve clonal crop diversity will be most effective when both folk classification and its genetic basis are considered together.
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farmer perspectives on oca Oxalis tuberosa oxalidaceae diversity conservation values and threats
Journal of Ethnobiology, 2016Co-Authors: Lauren J Moscoe, Eve EmshwillerAbstract:Abstract Traditional crops contribute to food security and agroecological sustainability, but their diversity is threatened by economic, environmental, and sociocultural factors. We use a case study of the Andean tuber crop oca (Oxalis tuberosa; Oxalidaceae), in Pisac District, Cusco Region, Peru, to explore the commonly held assumptions that: 1) farmers maintain traditional crop diversity for practical purposes and 2) that the major threats to this diversity occur when increased access to resources compromises farmers’ motivations for maintaining traditional crops. Using a qualitative research approach, we examine motivations for, and threats to, oca diversity in two smallholder farming communities. Farmers reveal agricultural, economic, and dietary and medicinal motivations for oca conservation, though they are most strongly motivated by intangible cultural factors. Farmers describe threats to some of these motivations, but they suggest that oca conservation is most immediately threatened by the oca wee...
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Diversity of Oxalis tuberosa Molina: a comparison between AFLP and microsatellite markers
Genetic Resources and Crop Evolution, 2015Co-Authors: Lauren J Moscoe, Eve EmshwillerAbstract:Traditional crops contribute to food security and agroecological sustainability, but their diversity is increasingly threatened by complex interplays of local and global sociocultural and economic change. Molecular markers are powerful tools to measure and characterize this diversity, and comparisons among different molecular marker systems are necessary to assess their appropriateness in different research contexts. Using a common sample set, we compare amplified fragment length polymorphism (AFLP) and microsatellite (simple sequence repeats; SSRs) techniques to assess their utility in research on the Andean tuber crop oca ( Oxalis tuberosa Molina, Oxalidaceae). We find that 26 of 27 individuals have distinct AFLP genotypes, and all 27 individuals have distinct SSR genotypes. Both markers systems cluster samples in agreement with morphotype groups and separate clusters with similar strength, but more variation occurs within AFLP-based clusters than within SSR-based clusters. In addition, correlation between marker systems of pairwise distances is positive and significant (R = 0.831, p = 0.001). Ultimately, we discuss each system’s advantages and disadvantages for future oca diversity research.
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The Role of Organic Acids in the Domestication of Oxalis tuberosa: A New Model for Studying Domestication Resulting in Opposing Crop Phenotypes^1
Economic Botany, 2011Co-Authors: E. Jane Bradbury, Eve EmshwillerAbstract:Los ácidos orgánicos y la domesticación de Oxalis tuberosa: un nuevo modelo para el estudio de la domesticación que resulta en los fenotipos domésticos opuestos. Aunque pocos cultivos presentan fenotipos domésticos directamente opuestos , estos cultivos pueden ser la clave para entender los procesos de domesticación que muestran conflicto en la presión selectiva en el ecosistema agrícola. Dos ejemplos relativamente bien conocidos son la yuca (Manihot esculenta Crantz), que tiene variedades de alto y bajo contenido de cianuro, y la papa (Solanum sección Petota). Entre las papas hay varias especies, incluyendo la papa común (Solanum tuberosum L.), que tienen bajos niveles de glicoalcaloides mientras otras especies como las "papas amargas", tienen elevados niveles de glicoalcaloides. Nosotros proponemos que Oxalis tuberosa Molina, oca, puede representar un tercer ejemplo de este sistema de cultivo, con niveles altos y bajos de ácidos orgánicos. Cada grupo de variedades de oca tiene diferentes practicas culturales respecto a su preparación como alimentos (categorías de uso), similar a las categorías de uso que se han descrito para las papas en los Andes (Brush et al. Economic Botany 35;70–88, 1981 ; Zimmerer Journal of Biogeography 18;165–178, 1991 ). Los análisis iniciales sugieren que los ácidos orgánicos en los tubérculos pueden deberse a una diferencia bioquímica importante entre el uso de categorías basadas en el ácido oxálico y los datos de pH. En este artículo examinamos nuestra interpretación de los ácidos orgánicos en los tubérculos de oca, además de destacar las áreas que merecen mayor investigación. The Role of Organic Acids in the Domestication of Oxalis tuberosa : A New Model for Studying Domestication Resulting in Opposing Crop Phenotypes. Though few crops display directly opposing domesticated phenotypes, these crops may be the key to understanding domestication processes that address conflicting selective pressures in the agricultural ecosystem. Two relatively well-known examples are cassava ( Manihot esculenta Crantz), which has high-cyanide and low-cyanide varieties, and potato ( Solanum section Petota ). Among the potatoes are several species, including the common potato ( Solanum tuberosum L.), that have low levels of glycoalkaloids and there are other species of “bitter potato” with elevated levels of glycoalkaloids. We propose that Oxalis tuberosa Molina, “oca,” may represent a third example of such a crop system, with opposing high organic acid and low organic acid cultivars. Each cultivar set has different cultural food preparation practices (“use-categories”), similar to the “use-categories” that have been described for potatoes in the Andes (Brush et al. Economic Botany 35;70–88, 1981 ; Zimmerer Journal of Biogeography 18;165–178, 1991 ). Our initial analyses suggest that organic acids in tubers may be an important biochemical difference between use-categories, based on both oxalic acid and pH data. Here, we review our understanding of organic acids in oca tubers, while highlighting areas that merit further investigation.
Geoffrey P Savage - One of the best experts on this subject based on the ideXlab platform.
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oxalate content of raw and cooked oca Oxalis tuberosa
Journal of Food Composition and Analysis, 2001Co-Authors: Chancherdchai Sangketkit, Geoffrey P Savage, Richard J Martin, Susan L MasonAbstract:Oca (Oxalis tuberosa Mol.) or New Zealand yam, in common with other members of this genus, contains oxalate, an antinutritive factor. Twelve South American and two New Zealand cultivars of oca were analysed for the total oxalate contents of tubers. Total oxalate levels ranged from 80 to 194 mg/100 g wet matter (WM). As these tubers are normally cooked before consumption, the oxalate levels were measured after they had been cooked by three conventional cooking methods. Oxalate levels ranged from 77 to 220 mg/100 g WM for boiled and steamed tubers, while the levels of oxalate found in baked tubers were significantly increased when compared to the raw tubers. The oxalate content of the baked tubers ranged from 164 to 335 mg/100 g WM. Total calcium content of the raw tubers ranged from 7.5 to 15.5 mg/100 g WM; cooking had little effect on the calcium content. Among cultivars mean oxalate/calcium ratio of the raw, boiled and steamed tubers ranged from 2.5 to 9.9. Baked tubers had a significantly increased oxalate/calcium ratio (mean for all cultivars 9.5). L'Oca (Oxalis tuberosa Mol.) est une plante a tubercule cultivee dans les Andes et en Nouvelle Zelande. Cette etude recherche les changements possibles dans les concentrations en oxalate, compose antinutritionnel, qui peuvent survenir avec la cuisson (ebullition, vapeur, a l'etouffee). Elle determine si la cuisson a un effet sur le ratio oxalate/calcium dans le tissu vegetal. Les tubercules cuits a l'etouffee presentent le taux d'oxalate et le ratio oxalate/calcium le plus fort. La cuisson a peu d'effet sur la teneur en calcium.
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the effect of cooking on the location and concentration of oxalate in three cultivars of new zealand grown oca Oxalis tuberosa mol
Journal of the Science of Food and Agriculture, 2001Co-Authors: P B E Albihn, Geoffrey P SavageAbstract:Oca (Oxalis tuberosa Mol) originates from South America but is now also grown commercially in New Zealand. It contains moderate amounts of oxalate, which is only present in its soluble form. The skin of the oca tuber is thought to contain more oxalate than the flesh. In this study the concentration of soluble oxalate was measured in the skin and outer and inner flesh and in the whole tuber of raw, boiled, baked and steamed oca. The analysis was carried out on the traditionally pinkish-red New Zealand cultivar and on the newly introduced cultivars 'Mellow Yellow' and 'Apricot Delight'. In the raw oca tuber the oxalate concentration in the skin is significantly higher than in the flesh (mean value 7.3 g kg fresh weight (FW) compared to 1.7 and 1.4 g kg - 1 FW in the outer and inner flesh respectively). The highest concentration was found in the skin of the pinkish-red cultivar (10.9 ± 1.0 g kg -1 FW). All cooking methods seemed to cause a migration of oxalate from the skin to the underlying flesh. On a fresh weight basis, baking significantly increased the oxalate concentration in the whole tuber, whereas boiling decreased the concentration and steaming had no significant effect (p La concentration en oxalate soluble a ete mesuree dans la peau, la chair, et le tubercule entier de l'oca (Oxalis tuberosa Mol) cru, bouilli, cuit au four et a la vapeur.Toutes les methodes de cuisson provoquent un migration de l'oxalate de la peau vers la chair. Par rapport au poids frais, l'oca bouillie a une teneur plus faible en oxalate, c'est donc la methode de preparation a privilegier quand une ingestion faible d'oxalate est desiree.
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sensory evaluation of new lines of oca Oxalis tuberosa grown in new zealand
Food Quality and Preference, 2000Co-Authors: Chancherdchai Sangketkit, Geoffrey P Savage, Richard J Martin, B P Searle, S L MasonAbstract:Abstract Five new and one local cultivar of oca or New Zealand yam ( Oxalis tuberosa ) were evaluated by a consumer-type panel for appearance, flesh colour, flavour, texture and overall acceptability of raw, steamed and baked tubers. The intensity, ‘just right’ or liking scores were analysed using the proportional odds model. Skin and flesh colour of tubers were also measured objectively using a colorimeter. For raw oca, panellists preferred bright red tubers, but size was also important. Flesh colour, bitterness and mealiness were important variables which described the overall acceptability of steamed oca, while only flesh colour and bitterness were important variables for baked oca. Cultivars which had flesh colour described as ‘bright yellow’, flavour as ‘no bitter taste’, and a ‘very slightly mealy’ texture were more preferred. Cultivars with higher yellow/blue ( b ∗ ) and chroma ( c ∗ ) values for cooked tuber skin and flesh colours were more acceptable.
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oxalates in oca new zealand yam Oxalis tuberosa mol
Journal of Agricultural and Food Chemistry, 1999Co-Authors: Alastair B Ross, Geoffrey P Savage, Richard J Martin, Leo P VanhanenAbstract:Oca (Oxalis tuberosa Mol.) or New Zealand yam, in common with other members of this genus, contains oxalate, an antinutritive factor. Twelve South American and two New Zealand cultivars of oca were analyzed for total and soluble oxalate contents of the tubers. The range of total oxalate levels was 92-221 mg/100 g of fresh weight. Levels of soluble and total oxalate extracted from the tubers were not significantly different, suggesting that no calcium oxalate is formed in the tubers. The oxalate concentrations obtained in this study for oca suggest that previously reported values are too low and that oca is a moderately high oxalate-containing food. This is the first report of a tuber crop containing moderate to high levels of soluble oxalates in the tubers and no insoluble oxalates.
David Campos - One of the best experts on this subject based on the ideXlab platform.
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hplc dad characterisation of phenolic compounds from andean oca Oxalis tuberosa mol tubers and their contribution to the antioxidant capacity
Food Chemistry, 2009Co-Authors: Rosana Chirinos, Indira Betalleluzpallardel, Anabel Huaman, Carlos Arbizu, Romina Pedreschi, David CamposAbstract:Abstract A qualitative and quantitative characterisation of the main non-anthocyanin phenolic compounds from two different colored oca ( Oxalis tuberosa Mol.) genotypes with potential antioxidant capacity was carried out by high performance liquid chromatography with photodiode array detection (HPLC-DAD). Phenolic compounds were fractionated in two main fractions: an aqueous (Faq) and a ethyl acetate fraction (Fea). In addition, the contribution of these phenolic fractions to the antioxidant capacity was evaluated. The Faq revealed the presence of caffeic, vanillic and cinnamic acid derivatives, flavan-3-ols and flavones derivatives, as the main non-anthocyanin phenolic compounds for both genotypes. Anthocyanins for the purple genotype were significantly present in this fraction. Acid hydrolysis revealed the presence of vanillic, caffeic and cinnamic acids and malvidin in Faq. The Fea was composed mainly of caffeic and cinnamic acid derivatives as well as flavan-3-ols, flavones and flavanone derivatives. Based on their UV–Vis spectral data the flavan-3-ols, flavones and flavanones detected in both fractions seem to correspond to bound forms of catechin, luteolin and apigenin and naringenin, respectively. The Faq fractions were the major contributors to the ABTS antioxidant capacity (77–82%). The results obtained in the present study suggest that oca tubers could potentially be considered beneficial for human health and for potential industrial applications.
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antioxidant capacity and secondary metabolites in four species of andean tuber crops native potato solanum sp mashua tropaeolum tuberosum ruiz pavon oca Oxalis tuberosa molina and ulluco ullucus tuberosus caldas
Journal of the Science of Food and Agriculture, 2006Co-Authors: David Campos, Rosana Chirinos, Carlos Arbizu, Giuliana Noratto, Willian Roca, Luis CisneroszevallosAbstract:Four species of edible tubers endemic to and domesticated in the Andes, native potato (Solanum sp.), mashua (Tropaeolum tuberosum Ruiz & Pav ´ on), oca (Oxalis tuberosa Molina) and ulluco (Ullucus tuberosus Caldas), were studied for their antioxidant capacity and associated secondary metabolites. The antioxidant capacity was measured using ABTS − radicals and total phenolics, carotenoids, anthocyanin, betaxanthin and betacyanin content were also characterized. The antioxidant capacity found in the crops studied ranged from 483 to 9800 µ gt rolox equiv. g −1 , phenolics ranged from 0.41 to 3.37 mg chlorogenic acid equiv. g −1 , anthocyanins ranged from 0.08 to 2.05 mg cyanidin 3-glucoside g −1 and carotenoids ranged from 1 to 25 µg β-carotene g −1 . The content of bioactive compounds was high and variable between crops and within the genotypes studied. In general, mashua tubers showed the highest antioxidant capacity and phenolic, anthocyanin and carotenoid content compared with other crops. Ulluco was the only crop that contained betalains in the acid form of betaxanthins (22-96 µ gg −1 )a nd betacyanins (64 µ gg −1 ) with no presence of carotenoids or anthocyanins. This is the first publication regarding the antioxidant capacity of and associated secondary metabolites in Andean tubers. This information can be useful in the identification of Andean tubers species and genotypes with potential value as a novel dietary source of antioxidants for food, and also for medicinal use. 2006 Society of Chemical Industry
Jeff J Doyle - One of the best experts on this subject based on the ideXlab platform.
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origins of domestication and polyploidy in oca Oxalis tuberosa oxalidaceae 2 chloroplast expressed glutamine synthetase data
American Journal of Botany, 2002Co-Authors: Eve Emshwiller, Jeff J DoyleAbstract:In continuing study of the origins of the octoploid tuber crop oca, Oxalis tuberosa Molina, we used phylogenetic analysis of DNA sequences of the chloroplast-active (nuclear encoded) isozyme of glutamine synthetase (ncpGS) from cultivated oca, its allies in the ‘‘Oxalis tuberosa alliance,’’ and other Andean Oxalis. Multiple ncpGS sequences found within individuals of both the cultigen and a yet unnamed wild tuber-bearing taxon of Bolivia were separated by molecular cloning, but some cloned sequences appeared to be artifacts of polymerase chain reaction (PCR) recombination and/or Taq error. Nonetheless, three classes of nonrecombinant sequences each joined a different part of the O. tuberosa alliance clade on the ncpGS gene tree. Octoploid oca shares two sequence classes with the Bolivian tuber-bearing taxon (of unknown ploidy level). Fixed heterozygosity of these two sequence classes in all ocas sampled suggests that they represent homeologous loci and that oca is allopolyploid. A third sequence class, found in eight of nine oca plants sampled, might represent a third homeologous locus, suggesting that oca may be autoallopolyploid, and is shared with another wild tuber-bearing species, tetraploid O. picchensis of southern Peru. Thus, ncpGS data identify these two taxa as the best candidates as progenitors of cultivated oca.
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origins of domestication and polyploidy in oca Oxalis tuberosa oxalidaceae nrdna its data
American Journal of Botany, 1998Co-Authors: Eve Emshwiller, Jeff J DoyleAbstract:As part of a study aimed at elucidating the origins of the octoploid tuber crop "oca," Oxalis tuberosa, DNA sequences of the internal trancribed spacer of nuclear ribosomal DNA (nrDNA ITS) were determined for oca and several wild Oxalis species, mostly from Bolivia. Phylogenetic analysis of these data supports a group of these species as being close relatives of oca, in agreement with morphology and cytology, but at odds with traditional infrageneric taxonomy. Variation in ITS sequences within this group is quite low (0-7 substitutions in the entire ITS region), contrasting with the highly divergent (unalignable in some cases) sequences within the genus overall. Some groups of morphologically differentiated species were found to have identical sequences, notably a group that includes oca, wild populations of Oxalis that bear small tubers, and several other clearly distinct species. The presence of a second, minor sequence type in at least some oca accessions suggests a possible contribution from a second genome donor, also from within this same species group. ITS data lack sufficient variation to elucidate the origins of oca precisely, but have identified a pool of candidate species and so can be used as a tool to screen yet unsampled species for possible progenitors.
Richard J Martin - One of the best experts on this subject based on the ideXlab platform.
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oxalate content of raw and cooked oca Oxalis tuberosa
Journal of Food Composition and Analysis, 2001Co-Authors: Chancherdchai Sangketkit, Geoffrey P Savage, Richard J Martin, Susan L MasonAbstract:Oca (Oxalis tuberosa Mol.) or New Zealand yam, in common with other members of this genus, contains oxalate, an antinutritive factor. Twelve South American and two New Zealand cultivars of oca were analysed for the total oxalate contents of tubers. Total oxalate levels ranged from 80 to 194 mg/100 g wet matter (WM). As these tubers are normally cooked before consumption, the oxalate levels were measured after they had been cooked by three conventional cooking methods. Oxalate levels ranged from 77 to 220 mg/100 g WM for boiled and steamed tubers, while the levels of oxalate found in baked tubers were significantly increased when compared to the raw tubers. The oxalate content of the baked tubers ranged from 164 to 335 mg/100 g WM. Total calcium content of the raw tubers ranged from 7.5 to 15.5 mg/100 g WM; cooking had little effect on the calcium content. Among cultivars mean oxalate/calcium ratio of the raw, boiled and steamed tubers ranged from 2.5 to 9.9. Baked tubers had a significantly increased oxalate/calcium ratio (mean for all cultivars 9.5). L'Oca (Oxalis tuberosa Mol.) est une plante a tubercule cultivee dans les Andes et en Nouvelle Zelande. Cette etude recherche les changements possibles dans les concentrations en oxalate, compose antinutritionnel, qui peuvent survenir avec la cuisson (ebullition, vapeur, a l'etouffee). Elle determine si la cuisson a un effet sur le ratio oxalate/calcium dans le tissu vegetal. Les tubercules cuits a l'etouffee presentent le taux d'oxalate et le ratio oxalate/calcium le plus fort. La cuisson a peu d'effet sur la teneur en calcium.
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sensory evaluation of new lines of oca Oxalis tuberosa grown in new zealand
Food Quality and Preference, 2000Co-Authors: Chancherdchai Sangketkit, Geoffrey P Savage, Richard J Martin, B P Searle, S L MasonAbstract:Abstract Five new and one local cultivar of oca or New Zealand yam ( Oxalis tuberosa ) were evaluated by a consumer-type panel for appearance, flesh colour, flavour, texture and overall acceptability of raw, steamed and baked tubers. The intensity, ‘just right’ or liking scores were analysed using the proportional odds model. Skin and flesh colour of tubers were also measured objectively using a colorimeter. For raw oca, panellists preferred bright red tubers, but size was also important. Flesh colour, bitterness and mealiness were important variables which described the overall acceptability of steamed oca, while only flesh colour and bitterness were important variables for baked oca. Cultivars which had flesh colour described as ‘bright yellow’, flavour as ‘no bitter taste’, and a ‘very slightly mealy’ texture were more preferred. Cultivars with higher yellow/blue ( b ∗ ) and chroma ( c ∗ ) values for cooked tuber skin and flesh colours were more acceptable.
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oxalates in oca new zealand yam Oxalis tuberosa mol
Journal of Agricultural and Food Chemistry, 1999Co-Authors: Alastair B Ross, Geoffrey P Savage, Richard J Martin, Leo P VanhanenAbstract:Oca (Oxalis tuberosa Mol.) or New Zealand yam, in common with other members of this genus, contains oxalate, an antinutritive factor. Twelve South American and two New Zealand cultivars of oca were analyzed for total and soluble oxalate contents of the tubers. The range of total oxalate levels was 92-221 mg/100 g of fresh weight. Levels of soluble and total oxalate extracted from the tubers were not significantly different, suggesting that no calcium oxalate is formed in the tubers. The oxalate concentrations obtained in this study for oca suggest that previously reported values are too low and that oca is a moderately high oxalate-containing food. This is the first report of a tuber crop containing moderate to high levels of soluble oxalates in the tubers and no insoluble oxalates.
