A simple method for the extraction of the isocoumarin 6-methoxymellein from carrot tissues

The use of boiling water for the extraction of 6-mcthoxymellein, a phytoalexin of carrot, was investigated instead of the conventional organic solvent method. The recovery (118%) obtained by a two-step extraction with boiling water compared favourably with that obtained by the conventional two-step extraction with acetone.     

Elicitation of 6-Methoxymellein in Carrot Leaves by Cercospora carotae

The inoculation of carrot leaves with conidia of the fungus Cercospora carotae induced the accumulation of 6-methoxymellein in the leaf blade and petiole, but not the root, of susceptible carrot plants. Root slices directly inoculated with mycelium of C carotae also accumulated 6-methoxymellein. In leaves, the peak in 6-methoxymellein levels coincided with the appearance of the first lesions, 9 days after inoculation. After this point the compound started to degrade steadily. This phytoalexin could thus be a defence compound against foliar pathogens of carrot. © 1997 SCI.     

Polyacetylenes in fresh and stored carrots (Daucus carota): relations to root morphology and sugar content

BACKGROUND: Carrot roots contain polyacetylenes, reported to be both beneficial and distasteful when consumed by humans. This study aimed to investigate the relationships between polyacetylene contents, root morphology and sugar content in order to increase the opportunities to optimise the composition of polyacetylenes in carrots. RESULTS: The falcarinol/total polyacetylene ratio was positively correlated with root size, the amount of sucrose and the sucrose/total soluble sugar ratio among both fresh and stored samples. Root size was inversely correlated with the amounts of falcarindiol and falcarindiol‐3‐acetate, especially among stored samples. Stored carrots exhibited an inverse correlation between polyacetylenes and the amount of soluble sugar. At a falcarinol content at harvest below approximately 200 mg kg^?1 dry weight the amounts of all polyacetylenes increased during storage, but above that level the amounts of all polyacetylenes instead decreased. CONCLUSION: The results indicate similarities in the activity of the enzymes transforming sucrose to hexoses and the enzymes transforming falcarinol to falcarindiol‐3‐acetate and falcarindiol. The negative correlation between root size and polyacetylenes seems to be partly due to dilution but also to a higher synthetisation rate in smaller roots. The results indicate the existence of an equilibrium regulating the level of falcarinol. Copyright © 2011 Society of Chemical Industry     

Acetylenic compounds in stored packaged carrots

Stored carrots vacuum packed in plastic shrink bags showed significant variations in the concentration of certain important secondary compounds. In the acetylene group, 18 compounds were isolated and measured. Only eight of these compounds have previously been reported as carrot constituents. The concentrations of 10 of the 18 increased with storage time, and six were present only in stored samples.     

The role of volatile compounds on aroma and flavour perception in coloured raw carrot genotypes

Quantitative analyses of volatile compounds isolated from raw carrots were combined with sensory analysis in order to identify the role of these compounds on aroma and flavour perception in coloured carrots. A sensory map of carrots with different colours was developed, the content of the isolated volatiles was determined and the role of these compounds for harsh flavour perception in raw coloured carrots was evaluated using multivariate data analysis. The sensory map showed that the coloured carrots formed distinct groups within the sensory profile. The orange genotypes were characterised by having significantly higher intensities in carrot flavour and aroma, while the reverse was true for the yellow genotypes. The purple genotype was characterised by having significantly higher intensity in sickenly sweet flavour and nutty flavour, and the red genotype was characterised by having significantly higher intensities in green aroma and flavour, bitterness and burning aftertaste. From the multivariate data analysis it was concluded that the isolated terpenes do correlate to the harsh flavour attributes.     

Effects of Genotype, Root Size, Storage, and Processing on Bioactive Compounds in Organically Grown Carrots (Daucus carota L.)

ABSTRACT: The effects of genotype, root size, storage, and processing on the content of bioactive compounds in carrots were determined to investigate the possibilities for optimizing the health-promoting properties of this vegetable. The content of polyacetylenes (falcarinol, falcarindiol, falcarindiol-3-acetate), carotenoids (α-and β-carotene), and isocoumarin 6-methoxymellein (6-MM) varied significantly between 6 genotypes of the Nantes type. The content of falcarindiol, falcarindiol-3-acetate, and 6-MM was significantly higher in small (50- to 100-g root size) than in extra large root sizes (>250-g root size). Refrigerated storage of the roots for 4 mo at 1 °C before processing resulted in a significantly higher content of polyacetylenes and no differences in the content of carotenoids and 6-MM compared with frozen storage of processed carrots. The content of falcarinol increased and that of falcarindiol and falcarindiol-3-acetate decreased during steam blanching of the carrots before freezing. No changes were observed in the content of carotenoids and 6-MM.     

Bioactivity of falcarinol and the influenceof processing and storage on its content in carrots (Daucus carota L)

The concentration‐dependent activity of the polyacetylene falcarinol ((9Z)‐heptadeca‐1,9‐dien‐4,6‐diyn‐3‐ol), isolated from carrots, was investigated in a bioassay with primary mammary epithelial cells in collagen gels and compared with that of β‐carotene, the orange pigment in carrots. Falcarinol showed biphasic activity, having stimulatory effects between 0.01 and 0.05 µg ml^?1 and inhibitory effects between 1 and 10 µg ml^?1, whereas β‐carotene showed no effect in the concentration range 0.001–100 µg ml^?1. The results are discussed in relation to the health‐promoting effects of carrots and related vegetables. Falcarinol was quantified in the carrot cultivars Bolero, Rodelika and Fancy by analytical reverse phase HPLC, subjected to various processing and storage conditions in order to study how long‐term storage, blanching, freezing and boiling influence the content of falcarinol. Long‐term storage of raw carrot cubes (1 cm³) reduced the falcarinol content by almost 35%. A similar reduction was found in steam‐blanched carrot cubes (1 cm³). Long‐term storage at ?24 °C of steam blanched carrot cubes did not reduce the falcarinol content further. A reduction of almost 70% in the falcarinol content was found in carrot pieces boiled in water for 12 min compared with raw carrots. Copyright © 2003 Society of Chemical Industry     

Changes in texture,microstructure and nutritional quality of carrot slices during blanching and freezing

Thermal processing of vegetables has pronounced effects on the cell structure, often lowering the final textural properties of the product. In order to investigate the effect of thermal processing on carrot, slices were subjected to different blanching and freezing treatments before frozen storage. Microwave-, steam- or water-blanched material was frozen and then stored at −24 °C. Steam-blanched carrots were subjected to blast freezing or cryogenic freezing at different temperatures before frozen storage. The influence of these process conditions on the texture (maximum load and slope), microstructure, dry matter, sugars, carotene and drip loss was investigated. Microwave blanching differed from the other blanching methods by resulting in a heterogenic cell structure. The content of dry matter, carotene and sucrose was higher following microwave blanching. Blast freezing resulted in low maximum load which seemed to be caused by major tissue damage. Concerning cryogenic freezing, lowering the temperature from −30 °C to −70 °C resulted in better preservation of the native microstructure together with an increase in maximum load, which was most pronounced after one month of storage. No significant effect was observed when lowering the temperature from −30 °C to −70 °C for any of the other measured parameters. © 1999 Society of Chemical Industry     

Effects of limonene on the growth and physiology of cabbage (Brassica oleracea L) and carrot (Daucus carota L) plants

Monoterpenes are plant‐based alternatives for pest control in sustainable agriculture. This study investigated the phytotoxic effects of the monoterpene limonene on white cabbage (cv Rinda and Lennox) and carrot (cv Parano and Splendid) plants. The effects of increasing concentrations (from 10 to 120 ml l^?1) of limonene on visible leaf injuries, growth, chlorophyll fluorescence, net photosynthesis and stomatal conductance were studied. Limonene concentrations of 90 and 120 ml l^?1 were significantly phytotoxic in both cabbage and carrot, depending on the cultivar. However, there were major differences in limonene responses between the cultivars in both species. In carrot, lower shoot and root biomass was related to lower chlorophyll fluorescence (indicating lower efficiency of the photochemical processes) in cv Splendid, whereas in cv Parano it was related to lower stomatal conductance (indicating reduced gas exchange), suggesting that the mechanism behind the phytotoxicity may be different in different cultivars. In cabbage, better limonene tolerance and faster recovery processes in cv Lennox compared with cv Rinda were evident through increasing efficiency of photochemistry (chlorophyll fluorescence), and in the higher stomatal conductance and net photosynthesis rates, providing energy for defence and repair action. Since direct phytotoxic effects were detected on carrot and cabbage with limonene, we conclude that critical threshold concentrations for cultivated plants should be determined before monoterpenes are widely used as repellents and deterrents. These thresholds should, as far as possible, be species‐ and cultivar‐specific in order to provide full protection of plants. Copyright © 2004 Society of Chemical Industry     

Effects of organic and conventional growth systems on the content of carotenoids in carrot roots, and on intake and plasma status of carotenoids in humans

BACKGROUND: The demand for organic food products has increased during the last decades due to their probable health effects, among others. A higher content of secondary metabolites such as carotenoids in organic food products has been claimed, though not documented, to contribute to increased health effects of organic foods. The aim was to study the impact of organic and conventional agricultural systems on the content of carotenoids in carrots and human diets. In addition, a human cross‐over study was performed, measuring the plasma status of carotenoids in humans consuming diets made from crops from these agricultural systems. RESULTS: The content of carotenoids in carrot roots and human diets was not significantly affected by the agricultural production system or year, despite differences in fertilisation strategy and levels. The plasma status of carotenoids increased significantly after consumption of the organic and conventional diets, but no systematic differences between the agricultural production systems were observed. CONCLUSION: The expected higher content of presumed health‐promoting carotenoids in organic food products was not documented in this study. Copyright © 2011 Society of Chemical Industry     

Sensory and chemical changes in five varieties of carrot (Daucus carota L) in response to mechanical stress at harvest and post‐harvest

Carrots harvested by hand or machine and given additional mechanical stress by shaking in a transport simulator were analysed for taste, flavour and content of sugars, terpenes, 6‐methoxymellein and ethanol as well as for ethylene production and respiration. Carrots stressed by shaking had higher ethylene production and respiration, higher content of ethanol and 6‐methoxymellein and lower levels of total terpenes, several individual terpenes and sugars. This corresponded to a higher sensory score for ethanol flavour and odour, bitter taste, earthy flavour, terpene flavour, aftertaste and sickeningly sweet taste and a lower score for acidic taste and sweet taste as measured by an expert taste panel. Ethanol content was highly correlated with ethanol flavour and odour and sickeningly sweet taste. Of five varieties tested, ‘Bolero’ ‘Panter’ and ‘Yukon’ were most sensitive to mechanical stress, whereas ‘Napa’ and ‘Newburg’ were most resistant. Hand‐harvested carrots were not significantly different from machine‐harvested carrots as regards chemical or sensory variables. Principal component analysis showed only slightly different placing of these samples in the score plot. A digital carrot could monitor the degree of mechanical stress to which the carrots were subjected. © 2001 Society of Chemical Industry     

Changes in carotenoids including geometrical isomers and ascorbic acid content in orange–carrot juice during frozen storage

Fruits and vegetables are highly perishable foods, which explains the need to apply preservation techniques, such as freezing. The aim is to combine shelf life extension with maintenance of sensory and nutrient characteristics. The stability of orange–carrot juice stored at –40 °C for 132 days was studied. The ascorbic acid and carotene contents and the influence of storage time were analysed. Carotenes were identified and quantified by liquid chromatography and ascorbic acid was determined by differential pulse polarography. The initial concentration of ascorbic acid was 27.09 mg/100 ml and decreased by 4.1% during the storage period. Vitamin A activity in the orange–carrot juice increased during the period studied, fitting a linear model (R²=0.87). Of the 14 carotenes identified, only antheraxanthin and the mixture of 9-cis-violaxanthin and neoxanthin decreased in concentration during the storage period.     

Sensory quality of ethylene‐exposed carrots (Daucus carota L,cv ‘Yukon’) related to the contents of 6‐methoxymellein,terpenes and sugars

Carrots were analysed for taste and odour and for contents of terpenes, 6‐methoxymellein and sugars during 3 weeks storage at 15 °C in an atmosphere containing ethylene (1 µl l⁻¹). The ethylene treatment caused an increase in 6‐methoxymellein and the conversion of higher amounts of sucrose to fructose and glucose compared to control carrots stored in air. This corresponded to higher sensory scores for bitterness and terpene flavour and a lower score for sweetness, as measured by an expert taste panel. Principal component analysis showed a more expressed bitter taste, earthy flavour, green flavour, terpene flavour and aftertaste in the ethylene‐treated carrots. Correlations were found between sweet taste and the content of sucrose (r = 0.91, p < 0.005) and between the contents of various terpenes (particularly γ‐terpinene, limonene and caryophyllene) and terpene flavour, green flavour, aftertaste and bitter taste (r ≥ 0.72, p < 0.05). In the air‐stored carrots these off‐flavours seemed to be masked by a high sucrose content. © 2000 Society of Chemical Industry     

Effect of low‐cost storage and packaging on quality and nutritive value of fresh and dehydrated carrots

Fresh carrots (Daucus carota L cv ‘Nantes’) were packed in Netlon and ventilated low‐density polyethylene bags and stored in ambient, cool chamber and cool store conditions. Blanching and drying conditions were standardised and the sliced carrots were dehydrated to 7–9% moisture content using the best blanching and drying combination. Dehydrated carrots were packed in single and double layers of high‐density polyethylene bags and stored in ambient and cool store conditions for 9 months. The shelf‐life of fresh carrots varied from 3 to 20 days depending on the packaging and storage condition. A reduction in β‐carotene and ascorbic acid content and an increase in electrolyte leakage were observed during storage of fresh carrots. Blanching and drying caused a significant reduction in β‐carotene and ascorbic acid content, which further decreased during storage of dried product. The storage study of dried product showed that retention of β‐carotene and ascorbic acid was better in double‐packed and cool‐stored samples, and it also showed minimum browning during storage. © 2000 Society of Chemical Industry     

Effects of cultivar,root weight,storage and boiling on carbohydrate content in carrots (Daucus carota L)

The effects of cultivar (n = 4), root weight (n = 4), storage (5 months) and boiling (7 min) and their interactions on the content of dry matter and carbohydrates were studied and ranked in carrots. Boiling had the greatest effect and had an influence on all variables except the ratio between sucrose and the monosaccharides glucose and fructose. The choice of cultivar was also of great importance as regards glucose, fructose and sucrose content, while dietary fibre and dry matter were much less affected, or even unaffected, by this factor. Root weight and storage were consistently of less significance than boiling and cultivar. Thus dietary fibre solubility, fructose content and the ratio between sucrose and the monosaccharides glucose and fructose were independent of the root weight, while storage had no impact on the dry matter content. After storage the cultivar Lonto had lost more dry matter than the other cultivars (10% versus mean 1% for the others, P = 0.009) and the sugar ratio between sucrose and the monosaccharides glucose and fructose had increased in the cultivar Amarant, while it decreased in the other cultivars (P < 0.001). Furthermore, Amarant had a lower loss of sugars (35%) following boiling than the other cultivars (mean 39%, P = 0.002). Storage and boiling interacted concerning soluble and insoluble dietary fibre, fibre solubility and glucose content. It is concluded that the various factors (especially boiling and cultivar) gave rise to such differences in carbohydrate content and composition that they might be of nutritional importance. The results may thus provide a basis for selecting raw material when studying possible health effects of carrots. Copyright © 2004 Society of Chemical Industry     

Effects of washing and packing on sensory and chemical parameters in carrots (Daucus carota L)

Carrots washed and packed by hand or machine and stored at 2, 10 or 20 °C in three different package types were analysed for taste, flavour and content of sugars, terpenes, 6‐methoxymellein and ethanol as well as for ethylene, CO₂ and O₂ concentrations in the packages. Carrots washed by machine had increased micro‐organism decay and higher sensory scores for bitter taste, aftertaste, terpene flavour and odour, green odour and earthy flavour. The ability of packages to ventilate was important to avoid anaerobic conditions that caused decreased sucrose content, increased production of ethanol and a higher intensity of ethanol flavour and sickeningly sweet taste. Increasing temperature enhanced the concentration of ethanol, CO₂ and ethylene and decreased the O₂ concentration as well as the content of sucrose and total sugar. High temperature also increased the intensity of ethanol flavour and odour, aftertaste, earthy flavour, terpene flavour and bitter taste. Bitter taste was positively correlated with 6‐methoxymellein level, although this level was below the sensory threshold. Bitter taste, earthy flavour and aftertaste were correlated with total terpenes and several individual terpenes. Carrots washed and packed early in the long‐term storage period (November) were more bitter and had a higher level of 6‐methoxymellein and a higher intensity of terpene flavour and odour, green flavour and earthy flavour than those handled in January or March. Copyright © 2004 Society of Chemical Industry     

Effects of freezing on the pigment content in green beans and padrón peppers

 The amounts of chlorophylls a and b, β-carotene and lutein in green beans, blanched green beans and Padrón peppers, all frozen at −22 °C, were monitored over 12 months by reverse-phase, gradient HPLC (C18 column, visible detection). In unblanched beans, these amounts of the pigments decreased considerably during month 1, but were generally stable during the next 11 months (β-carotene content decreased further in month 2 before stabilizing). Similar results were obtained for blanched beans, but decreases were offset by increases due to blanching (carotenoids) and lipoxygenase deactivation (β-carotene), or enhanced by blanching-induced decreases (chlorophylls). In contrast, the amounts of pigments in frozen Padrón peppers fluctuated around more or less constant values over the 12 months. Freezing in bags sealed under vacuum lead to moderate decreases in chlorophyll a in Padrón peppers and in β-carotene in blanched green beans. Received: 22 July 1996 / Revised version: 4 December 1996     

The effects of topical treatments with 6-pentyl-2-pyrone and structural analogues on stem end postharvest rots in kiwifruit due to Botrytis cinerea

The picking wounds in kiwifruit formed by breaking off the pedicels at harvest were treated topically with the naturally occurring lactones 6-pentyl-2-pyrone (6PP), decano-δ-lactone (DL) and 2-deceno-δ-lactone (massoialacetone: ML), and with the synthetic fungicide vinclozolin. 6PP was applied at rates from 0·4 to 4 mg, neat or diluted in oil, water or acetone. 6PP treatments consistently reduced the incidence of Botrytis cinerea storage rots to low levels in both inoculated and naturally infected fruit. For inoculated fruit, control was achieved even when treatment was delayed up to 2 days from inoculation. ML gave significant but lesser control than 6PP, while DL was not generally effective. DL was also less effective than ML or 6PP at suppressing B cinerea inoculum germination in vitro. Much lower rates of vinclozolin (8 or 70 μg) also gave significant control of storage rots. Such topical treatment methods permit control of storage diseases with similar application quantities to currently accepted preharvest fungicide treatments. © 1998 SCI.