Waste from peach (Prunus persica) processing used for optimisation of carotenoids ethanolic extraction

The processing of peaches to produce fruit pulp generates solid and liquid wastes rich in phytochemicals, such as carotenoids; thus, the objective of this work was to study the use of this waste for carotenoid extraction based on a complete experimental design and using response surface methodology. The parameters studied were the amount of solvent (20–50 mL), the number of extractions (1–5) and the extraction time (10–30 min). The extracts were analysed by spectrophotometry and the optimised conditions by HPLC. The optimised results were four extractions of 10 min using 38.5 mL of ethanol, which presented a yield of 168.59 μg g^?1 DW of total carotenoids of which 67.55 μg g^?1 corresponds to β‐carotene, 86.75 μg g^?1 to cryptoxanthin, 12.08 μg g^?1 to zeaxanthin and 2.2 μg g^?1 to lutein, which representing 66% of extraction pigments relative to the total content of carotenoids present in the peach waste.     

Phenolic and carotenoid profiles of papaya fruit (Carica papaya L.) and their contents under low temperature storage

BACKGROUND: Tropical fruits are rich in phenolic and carotenoid compounds, and these are associated with cultivar, pre‐ and postharvest handling factors. The aim of this work was to identify major phenolics and carotenoids in ‘Maradol’ papaya fruit and to investigate their response to storage temperature. RESULTS: Ferulic acid, caffeic acid and rutin were identified in ‘Maradol’ papaya fruit exocarp as the most abundant phenolic compounds, and lycopene, β‐cryptoxanthin and β‐carotene were identified in mesocarp as the major carotenoids. Ranges of contents of ferulic acid (1.33–1.62 g kg^?1 dry weight), caffeic acid (0.46–0.68 g kg^?1 dw) and rutin (0.10–0.16 g kg^?1 dw) were found in papaya fruit, which tend to decrease during ripening at 25 °C. Lycopene (0.0015 to 0.012 g kg^?1 fresh weight) and β‐cryptoxanthin (0.0031 to 0.0080 g kg^?1 fw) were found in fruits stored at 25 °C, which tend to increase during ripening. No significant differences in β‐carotene or rutin contents were observed in relation to storage temperature. CONCLUSION: Phenolics and carotenoids of ‘Maradol’ papaya were influenced by postharvest storage temperature with exception of β‐carotene and rutin. Ripe papaya stored at 25 °C had more carotenoids than those stored at 1 °C. Low (chilling) temperature (1 °C) negatively affected the content of major carotenoids, except β‐carotene, but preserved or increased ferulic and caffeic acids levels, as compared to high (safe) temperature (25 °C). Copyright © 2010 Society of Chemical Industry     

Comparison of releasing bound phenolic acids from wheat bran by fermentation of three Aspergillus species

Wheat bran was fermented at 28 °C for 7 days under 70% humidity by Aspergillus niger, Aspergillus oryzae and Aspergillus awamori. Total phenolic content (TPC) of the unfermented sample was 1531.5 μg g^?1 wheat bran. After the fermentation of Aspergillus awamori, Aspergillus oryzae and Aspergillus niger, TPC reached 5362.1, 7462.6 and 10 707.5 μg g^?1, respectively. The antioxidant activity in the extractions of fermented wheat bran also increased significantly compared with the unfermented sample (P < 0.05). Aspergillus niger showed the greatest capacity to release bound ferulic acid (416.6 μg g^?1). Aspergillus oryzae and Aspergillus awamori had the advantages of releasing more chlorogenic acid (84.0 μg g^?1) and syringic acid (142.3 μg g^?1), respectively. The destructive effect of Aspergillus niger on wheat bran structure was the strongest, followed by that of Aspergillus oryzae. This effect of Aspergillus niger may be due to its higher cellulase, xylanase, arabinofuranosidase and β‐xylosidase activities. Besides, Aspergillus oryzae possessed higher β‐glucosidase activity, and Aspergillus awamori had higher α‐amylase and feruloyl esterase activities. Aspergillus niger may be the best to release bound phenolic acids in the three Aspergillus species. These will provide the helpful information for understanding mechanism of the fermentation by Aspergillus species releasing bound phenolic in wheat bran.     

The antioxidant activity and the composition of free and bound phenolic acids in dough of wheat flour enriched by Boletus edulis after mixing and thermal processing

The porcino is good source of phenolics and has been used to enrich wheat flour. The antioxidant activity and the content and composition of free and bound phenolic acids in the dough of wheat and porcino flour mixture (70:30 w/w) were investigated. The free form in the amount of 1305.76 μg g^?1 was the main part of the phenolic content in the flour mixture. By dough mixing, the content of free phenolics increased by approximately 70%. Further thermal processing decreased the content of both forms of phenolics compared to dough after mixing, but the content of free phenolics of 1764.24 μg g^?1 is still higher than in the flour mixture. The stability of the detected phenolic acids during mixing and thermal processing depended on whether they were in free or bound form. After thermal processing, the total content of detected phenolic acids was 683.31 μg g^?1, indicating that approximately 87% of the total content of phenolic acids detected in flour mixture was retained.     

Antioxidative and anti‐inflammatory potential of phenolics from purple basil (Ocimum basilicum L.) leaves induced by jasmonic,arachidonic and β‐aminobutyric acid elicitation

The study presents changes in the phenolic levels, antioxidant and anti‐inflammatory potential of purple basil leaves caused by different chemical elicitors: arachidonic acid (AA), jasmonic acid (JA) and β‐aminobutyric acid (BABA). The application of the all tested elicitors increased the concentration of phenolic compounds, including flavonoids and phenolic acids; especially, in comparison with control (457.62 μg g^?1 FW), the rosmarinic acid level significantly increased after AA and JA treatment ‐ 705.0 and 596.5 μg g^?1 FW, respectively. Phenolics from AA‐elicited plants showed the highest anti‐inflammatory activities designated as lipoxygenase (EC₅₀ = 1.67 mg FW mL^?1) and cyclooxygenase inhibition (EC₅₀ = 0.31 mg FW mL^?1). Elicitors' treatments (especially AA and JA) may be a very useful biochemical tool for improving the production of phenolic compounds in purple basil leaves.     

Comparative study of the essential oils of three Beilschmiedia species and their biological activities

This study was designed to examine the chemical compositions of the essential oils from three Beilschmiedia species and antioxidant, antimicrobial, antityrosinase, acetylcholinesterase and anti‐inflammatory activities. The essential oils of B. kunstleri, B. maingayi, B. penangiana gave β‐caryophyllene (10.6–12.1%), β‐eudesmol (17.5–24.1%) and δ‐cadinene (17.5–28.7%) as the most abundant components respectively. The bark oil of B. maingayi showed the highest activity in β‐carotene/linoleic acid (125.9%) and phenolic content (288.2 mg GA g^?1), while B. penangiana bark oil was found to have strong activity in DPPH (IC₅₀ 84.7 μg mL^?1) and ABTS (IC₅₀ 108.3 μg mL^?1). The essential oils of B. penangiana showed the best activity against Candida glabrata with MIC value 31.3 μg mL^?1. The bark oil of B. penangiana gave 82.5% tyrosinase inhibiton. The leaf oil of B. maingayi gave the highest inhibition in AChE (66.6%) and lipoxygenase (77.0%) assay. Our findings demonstrate that the essential oils have great potential for applications in pharmaceutical and food industries.     

Carotenoids in yellow‐ and red‐fleshed papaya (Carica papaya L)

Vitamin A deficiency is a disorder of public health importance in Sri Lanka. A recent national survey revealed that 36% of preschool children in Sri Lanka have vitamin A deficiency (serum retinol <0.2 µg ml^?1). In view of its well‐established association with child morbidity and mortality, this is a reason for concern. One of the main fruits which has been recommended for prevention of vitamin A deficiency in Sri Lanka is papaya (Carica papaya L). In this study the carotenoid profiles of yellow‐ and red‐fleshed papaya were analysed by medium‐pressure liquid chromatography (MPLC) and UV‐vis spectrophotometry. A section of yellow‐fleshed papaya showed small carotenoid globules dispersed all over the cell, whereas in red‐fleshed papaya the carotenoids were accumulated in one large globule. The major carotenoids of yellow‐fleshed papaya were the provitamin A carotenoids β‐carotene (1.4 ± 0.4 µg g^?1 dry weight (DW)) and β‐cryptoxanthin (15.4 ± 3.3 µg g^?1 DW) and the non‐provitamin A carotenoid ζ‐carotene (15.1 ± 3.4 µg g^?1 DW), corresponding theoretically to 1516 ± 342 µg kg^?1 DW mean retinol equivalent (RE). Red‐fleshed papaya contained the provitamin A carotenoids β‐carotene (7.0 ± 0.7 µg g^?1 DW), β‐cryptoxanthin (16.9 ± 2.9 µg g^?1 DW) and β‐carotene‐5,6‐epoxide (2.9 ± 0.6 µg g^?1 DW), and the non‐provitamin A carotenoids lycopene (11.5 ± 1.8 µg g^?1 DW) and ζ‐carotene (9.9 ± 1.1 µg g^?1 DW), corresponding theoretically to 2815 ± 305 µg kg^?1 DW mean RE. Thus the carotenoid profile and organisation of carotenoids in the cell differ in the two varieties of papaya. This study demonstrates that carotenoids can be successfully separated, identified and quantified using the novel technique of MPLC. Copyright © 2003 Society of Chemical Industry     

Effect of extraction method and ripening stage on banana peel pigments

Carotenoids are one of the most widespread pigments in nature and can be used as health‐promoting natural food colorants. Banana peel, which is a by‐product of banana processing, contains a range of bioactive compounds including carotenoids. There is no published research on the extraction of food‐grade carotenoids from banana peels. This study evaluated the change in the banana peel carotenoid content over its ripening stages and determined the best possible solvent to extract carotenoid for food applications. The solvents permitted under Food Standard Australia New Zealand were used in the study. Ripeness stage 5 contained the highest content of total carotene at 1.86 μg g^?1 of banana peel. From one gram of banana peel, 0.57 μg of xanthophyll and 0.84 μg of beta‐carotene were extracted from ripening stage 5 with a solvent combination of hexane–diethyl ether–acetone and hexane–diethyl ether, respectively.     

Polyphenolic and phytochemical content of Cucumis sativus seeds and study on mechanism of preservation of nutritional and quality outcomes in enriched mayonnaise

Oxidative rancidity in food emulsions leads to a reduction in shelf life. Synthetic antioxidants are widely used in food industry to prevent the development of rancidity. The present study was focussed on investigating the antioxidant potential of Cucumis sativus seeds (CSS) and correlates these findings with mayonnaise enrichment and extends its shelf life. CSS exhibited the highest abundance in phenolic compounds (93.5 ± 0.1 mgGAE g^?1), flavonoids (57.4 ± 0.1 mgQE g^?1), β‐carotene (19.46 ± 0.4 mg carotenoids per 100 g) and high free radical scavenging activity. CSS (200 ppm) and butylated hydroxyanisole (200 ppm) were incorporated in mayonnaise and the oxidative stability was evaluated by peroxide, p‐anisidine and TBARS values during storage at different temperatures. Organoleptic evaluations indicated that CSS enriched sample was recorded the highest overall acceptability. The results from our study will provide scientific basis for CSS as natural preservative against lipid oxidation or food enrichment while developing functional foods.     

Phytochemical composition and antioxidant activity of peach as affected by pasteurization and storage duration

Fruit are very perishable and are often preserved as heat-processed foods. Clingstone peach [Prunus persica (L.) Batsch ‘Catherine’] fruit were heat-treated at 90 °C for 5 min and stored under aseptic conditions at room temperature (ca. 22 °C) for 90 days. Significant reductions in total carotenoids were observed immediately after pasteurization but total antioxidant activity and the concentration of total phenolics were unaffected. Pasteurization induced significant reductions in the concentration of protocatechuic acid (from 10.2 to 5.8 μg/g fw), zexanthin and β-cryptoxanthin. Significant reduction in antioxidant activity, expressed as ascorbic acid equivalents, from 0.52 to 0.25 mg/g fw, was observed during storage of pasteurized peach for 90 days. Total phenolics, expressed as gallic acid equivalents, decreased during storage from 0.57 to 0.28 mg/g fw and total carotenoids decreased from 4.0 to 1.3 μg/g fw. Procyanidin B1 increased from 15.8 to 26.8 μg/g fw and chlorogenic acid and neochlorogenic acid increased 35 and 43%, respectively. (?)-Epicatechin decreased during storage from 13.1 to 4.0 μg/g fw and quercetin-3-glucoside from 7.3 to 4.4 μg/g fw. All carotenoids decrease significantly with the exception of zeaxanthin, which increased during storage. Storage duration strongly affected the concentration of phenolics and carotenoids in pasteurized peach.     

Comparison of the antioxidant activities of roasted and explosive puffed coffees

We investigated the explosive process effect on antioxidant activities of coffee bean. The total polyphenol contents of powdered extract of explosive puffing coffee bean at 0.75 MPa (PEP 7.5) and powdered extract of explosive puffing coffee bean at 0.9 MPa (PEP 9.0) were at a significantly higher than that of the powdered extract of roasting coffee bean (PER) (P < 0.05). PEP 7.5 showed the highest levels of 3‐CQA (86.23 μg mg^?1), 4‐CQA (43.71 μg mg^?1), and 5‐CQA (31.66 μg mg^?1), and PEP 9.0 had also similar levels of chlorogenic acids, with 3‐CQA (77.99 μg mg^?1), 4‐CQA (43.71 μg mg^?1), and 5‐CQA (30.32 μg mg^?1). PEP 7.5 and PEP 9.0 showed relatively higher antioxidant capacities in DPPH, ABTS, taurine, FRAP, and β‐carotene/linoleic acid assays. PEPs partly recovered the HepG2 cell damage induced by t‐BOOH. These results suggest that puffed coffee has beneficial health effects, and could be used for the development of novel processed coffee products.     

Biochemical characterisation of the seed oils of four safflower (Carthamus tinctorius) varieties grown in north‐eastern of Morocco

The quality of the oil of four safflower varieties, originating from Spain (Rancho), India (Sharda) and Morocco (Cartamar and Cartafri), which were cultivated at the experimental station in Oujda (a semi‐arid region of eastern Morocco) was evaluated through analysis of their phenolic and carotenoid contents. The composition of the phenolic compounds of safflower oil has not yet been documented. Therefore, in this preliminary study, Thirty different phenolic compounds were identified, and significant differences between the oil varieties were observed (P < 0.05). In the seed oil from the Rancho and Sharda safflower varieties, the main phenolic compound was trans‐chalcone, representing 13.45% and 11.8%, respectively, of the total phenolics, whereas in Cartamar and Cartafri oils, naringin accounted for 26.82% and 16.5%, respectively, of the total phenolics. The total carotenoid contents ranged from 1.13 mg kg^?1 (Rancho) to 1.34 mg kg^?1 (Cartamar and Cartafri). We observed that β‐cryptoxanthin (0.31–0.37 mg kg^?1) and β‐carotene (0.3–0.35 mg kg^?1) were the predominant carotenoids in all of the safflower oils that were studied.     

Validation of analytical method for α‐dicarbonyl compounds using gas chromatography–nitrogen phosphorous detector and their levels in alcoholic beverages

This study aimed to establish an analytical method for α‐dicarbonyl compounds (α‐DCs) including glyoxal, methylglyoxal and diacetyl, to determine the content of α‐DCs in 101 various alcoholic beverages using gas chromatography–nitrogen phosphorous detector (GC‐NPD) and to perform exposure assessment. The limit of detection and limit of quantification for α‐DCs were 0.05–0.22 and 0.15–0.70 μg g^?1, respectively. The accuracy and precision were validated in five matrices. The raspberry fruit wine had the highest value at 139.74 μg g^?1 total α‐DCs. The lowest α‐DC concentration among the beverages was detected in rice wine (Makgeolli) at 1.59 μg g^?1. The levels of α‐DCs in various samples were detected as follows: 1.59–56.68 μg g^?1 in rice wine (Makgeolli), 2.73–16.77 μg g^?1 in beer, 8.22–139.74 μg g^?1 in fruit wine and 8.17–91.56 μg g^?1 in rice wine (Cheongju). The estimated daily intake of α‐DCs in the intake‐only group and population group was calculated as 4.22–97.94 μg kg^?1 bw day^?1 and 0.28–7.13 μg kg^?1 bw day^?1, respectively.     

Comparative study of antioxidant and antibacterial properties of the edible mushrooms Pleurotus levis,P. ostreatus,P. pulmonarius and P. tuber‐regium

Comparative studies of functional properties among closely related mushroom species, supported by molecular identification, standard cultivation and extraction protocols, are not well documented. We compared antioxidant and antibacterial properties of standardised hydroalcoholic extracts of four Pleurotus species (P. levis, P. ostreatus, P. pulmonarius and P. tuber‐regium). Antioxidant properties were investigated using DPPH and ABTS radical scavenging capacity, total phenolic content, β‐carotene‐linoleic and ORAC assays. Antibacterial effect was assessed using the microplate method. The functional properties of standardised mushroom extracts were different in species studied. β‐carotene–linoleic acid and ORAC assays showed high antioxidant activity, particularly in P. ostreatus. Pleurotus tuber‐regium exhibited the lowest antioxidant activity in the ORAC assay (3316.0 μmol of trolox equivalent mL^?1), but exerted the most potent bacteriostatic and bactericidal activity. Bacillus subtilis showed a high degree of susceptibility to a very low concentration (3.33 μg mL^?1) of P. levis extract. Remarkable antioxidant and antibacterial properties were found in P. levis and P. tuber‐regium compared to the other species studied that are cultivated commercially.     

Bioactive components,ABTS radical scavenging capacity and physical stability of orange,yellow and purple sweet potato (Ipomoea batatas) powder processed by convection‐ or vacuum‐drying methods

This study aims to investigate the antioxidant properties and physical stability of convection‐ or vacuum‐dried orange, yellow and purple sweet potato (Ipomoea batatas) powder upon room temperature storage at different relative humidity (RH) of 33%, 43%, 54% and 75% for 25 days. Both convection and vacuum‐dried samples had lower total phenolic content (TPC), anthocyanin content and antioxidant activity compared to the fresh samples. Vacuum‐dried powder retained higher antioxidant activity than convection‐dried powder. Storage of the powder at high RH of 75% resulted in apparent clump formation, which was likely attributed to the decrease of glass transition temperature (T_g). In general, purple sweet potato powder contained the highest TPC (255.0 mg GAE 100 g DW^?1) and antioxidant activity (1924.0 μmol TEAC 100 g DW^?1), while orange powder had the highest beta‐carotene content (127.2 mg 100 g DW^?1). Vacuum‐dried sweet potato powder, which has relatively higher antioxidant activity, could be a potential functional ingredient or natural colourant for the food industry.     

Variation in the carotenoid composition of acerola and its processed products

Acerola is now commercially produced and processed in Brazil. Known for its very high vitamin C content, this fruit is also a good source of β‐carotene. The present study was carried out to verify variation in the carotenoid composition along the food chain. Neoxanthin, violaxanthin, lutein, β‐cryptoxanthin, α‐carotene and β‐carotene were found in the acerola fruit. β‐Carotene predominated with mean concentrations of 12.4 and 38.1 µg g^?1 in the ripe fruit, 8.8 and 30.1 µg g^?1 in the peeled ripe fruit and 5.4 and 12.0 µg g^?1 in the partially ripe fruit of an undefined variety taken from home gardens and the commercial cultivar Olivier, respectively. Aside from β‐carotene, β‐cryptoxanthin increased significantly in both garden and commercial fruits and violaxanthin in the latter fruits during ripening. Peeling reduced β‐carotene in both garden and commercial lots, violaxanthin decreased in the commercial fruits, and the other carotenoids remained virtually unchanged. Four brands of frozen pulp and three brands of processed juice had variable and markedly lower carotenoid levels than those of the fresh fruit, indicating that the processing should be improved. Copyright © 2006 Society of Chemical Industry     

Effect of fermentation by Bacillus subtilis on antioxidant and cytotoxic activities of black rice bran

Black rice bran was fermented with Bacillus subtilis KU3 isolated from Korean traditional food, Kimchi. Antioxidant and cytotoxic activities of the fermented black rice bran were investigated. Total phenolic and anthocyanin contents decreased from 171.54 mg GAE g^?1 and 2.31 mg g^?1 to 139.13 mg GAE g^?1 and 2.12 mg g^?1, respectively, after fermentation. Antioxidant activities determined by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, β‐carotene bleaching and ferric thiocyanate assay were correlated with total phenolic and anthocyanin contents. Non‐fermented black rice bran extract (NFBE) showed greater antioxidant activities than fermented black rice bran extract (FBE). Cytotoxic activities measured by MTT assay showed that both NFBE and FBE had over 50% activities. The cytotoxic activities of FBE against MCF‐7 and HeLa cells were 71.65% and 68.07%, respectively, at 8.0 mg mL^?1, but those of NFBE were lower than 50%. These results suggested that the cytotoxic activity of black rice bran improved through fermentation, while antioxidant activity reduced.     

Physicochemical characterisation and oxidative stability of refined hoki oil,unrefined hoki oil and unrefined tuna oil

Physicochemical characterisation and oxidative stability of refined hoki oil, unrefined hoki oil and unrefined tuna oil were carried out in the present study. Tuna oil contains a higher percentage of polyunsaturated fatty acids (42.57%) than the hoki oils (28.79–30.13%), which have higher percentages of monounsaturated fatty acids (45.02–47.16%). All oils showed a good ratio of n‐3 to n‐6 fatty acid (7.01–8.10). Cholesterol contents in the unrefined hoki (5149.40 μg g^?1) and tuna (2045.48 μg g^?1) oils were higher than the refined hoki oil (1411.27 μg g^?1). Tuna has a higher concentration of natural α‐tocopherol (752.49 μg g^?1) but lower concentration of vitamin A (110.99 μg g^?1) than unrefined hoki oil (151.44 μg g^?1 and 997.60 μg g^?1, respectively). Higher percentages of unsaponifiable matter were found in the hoki oils (4.90–7.24%) compared with the tuna oil (0.56%). The hoki oils appear more yellow than the tuna oil, which is darker by comparison. Moisture, p‐anisidine value and free fatty acid contents in the hoki oils were lower than the tuna oil. Other indicators of oxidative stability showed that the hoki oils were more stable than the tuna oil.     

Comparative study on antioxidant properties of carrot juice stabilised by high‐intensity pulsed electric fields or heat treatments

BACKGROUND: The effect of high‐intensity pulsed electric field (HIPEF) processing (35 kV cm^?1 for 1500 µs using 6‐µs bipolar pulses at 200 Hz) on the antioxidant features (vitamin C, β‐carotene, total phenolic compounds and antioxidant capacity) of carrot juice as well as on peroxidase activity was investigated and compared to the observed in heat pasteurised juices (90 °C for 60 s or 30 s) having the fresh juice as a reference. RESULTS: HIPEF and heat‐treated carrot juices had higher β‐carotene and lower vitamin C contents than the untreated juices immediately after processing. The antioxidant capacity of the juices was significantly modified neither by HIPEF nor by thermal treatments. POD activity decreased drastically (≥93.3%) after processing irrespective of the treatment applied. Vitamin C and β‐carotene content decreased throughout the storage following an exponential trend (R² = 0.801–0.984) with degradation rates between 1.7 × 10^?2 and 3.5 × 10^?2 day^?1. Vitamin C and β‐carotene contents were better maintained in HIPEF‐treated than in heat‐pasteurised juices throughout the storage. Total phenolic content and the antioxidant capacity of the HIPEF‐treated juice did not substantially differ from that of the thermally treated juice for 56 days. CONCLUSION: HIPEF processing may help to achieve fresh‐like carrot juices with increased amounts of health‐related phytochemicals. Copyright © 2009 Society of Chemical Industry     

Antioxidant capacity and secondary metabolites in four species of Andean tuber crops: native potato (Solanum sp.), mashua (Tropaeolum tuberosum Ruiz & Pavón), Oca (Oxalis tuberosa Molina) and ulluco (Ullucus tuberosus Caldas)

Four species of edible tubers endemic to and domesticated in the Andes, native potato (Solanum sp.), mashua (Tropaeolum tuberosum Ruiz & Pavón), 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 µg trolox 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 µg g^?1) and betacyanins (64 µg g^?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. Copyright © 2006 Society of Chemical Industry