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1.
The total glycoalkaloid concentrations in aerial and subterranean tubers of 14 potato genotypes were measured using high-performance liquid chromatography immediately after harvest. Post-harvest, aerial tubers from all genotypes were exposed to 144 h continuous fluorescent light; additionally three genotypes (cvs Home Guard, Kerrs Pink and Desiree) were subjected to mechanical wounding prior to glycoalkaloid analysis. Variations in glycoalkaloid concentrations between aerial tubers taken from a single genotype (cv Kerrs Pink) were determined by analysis of eight aerial tubers formed in the second leaf axil, selected from separate individual plants. Irrespective of genotype, total and individual glycoalkaloid concentrations were higher in aerial than in subterranean tubers. The highest glycoalkaloid concentrations were found in aerial tubers of cv Kerrs Pink (1343·0 mg kg−1 FW) and lowest in cv Lindsey (301·0 mg kg−1 FW). Ratios of α-chaconine: α-solanine in aerial tubers differed significantly ( P< 0·05) from those in subterranean tubers of cv Cara, Golden Wonder, Home Guard, Lindsey, Maris Piper, Record and 8859 indicating that exposure to light during aerial tuber growth enhanced the synthesis of one glycoalkaloid to a greater degree than the other. In all cultivars except cv Maris Piper, exposure of aerial tubers to 144 h continuous fluorescent light post-harvest increased total and individual glycoalkaloids compared with dark-treated controls. However, the ratios of α-chaconine: α-solanine in all genotypes except cv Golden Wonder (decreased α-chaconine: α-solanine, P< 0·05) were not significantly altered in comparison with dark controls, indicating that light exposure of aerial tubers post-harvest fails to enhance selectively synthesis of individual glycoalkaloids in the majority of cultivars. Regardless of cultivar, total glycoalkaloid, α-solanine and α-chaconine concentrations were higher in wounded than unwounded aerial tubers. Wounding stimulated synthesis of α-solanine more than α-chaconine ( P< 0·05) in cv Home Guard and Desiree. Glycoalkaloid concentrations in aerial tubers varied widely from a minimum of 1010 mg kg−1 to a maximum of 2520 mg kg−1 FW when harvested from individual plants of cv Kerrs Pink but selected from equivalent positions on the plant. Throughout the experiments large, non-significant increases in total and individual glycoalkaloid concentrations were recorded following light and wounding treatments. The scientific implications of aerial tuber formation are discussed.  相似文献   

2.
The total glycoalkaloid concentration of dormant (non-sprouted) and sprouted potato tubers cv Pentland Hawk was measured following 13 days continuous illumination (250 μmol m?2 s?2 photosynthetically active radiation) using high-performance liquid chromatography. Comparisons were made of the influence of three sources of illumination: high-pressure mercury, high-pressure sodium and fluorescent tube type warm white. Glycoalkaloid concentrations in both dormant and sprouted tubers increased over 13 days illumination regardless of the form of illumination used. Glycoalkaloid concentrations accumulated with time in dormant and sprouted tubers exposed to sodium and fluorescent light but fluctuated in those exposed to mercury light. Dormant tubers were more sensitive to illumination than sprouted tubers regardless of light souce. Fluorescent light was associated with maximum glycoalkaloid synthesis in dormant tubers; while sodium light enhanced glycoalkaloid synthesis in sprouted tubers to the greatest extent. Mercury light weakly elicited glycoalkaloid synthesis in both sets of tubers. Exposure of dormant tubers to continuous light altered the ratio of α-chaconine to α-solanine irrespective of illumination source.  相似文献   

3.
The total glycoalkaloid concentration of non‐sprouted potato tubers, cvs Marfona, Fianna, Maris Piper, Kestrel and Golden Wonder, was measured following 15 days of continuous illumination (250 µmol m−2 s−1 photosynthetically active radiation) using high‐performance liquid chromatography. Comparisons were made of the influence of four sources of illumination: fluorescent tube‐type warm white, high‐pressure sodium, high‐pressure mercury types MB/U and MBFR/U. Irrespective of cultivar, glycoalkaloid concentrations of tubers placed in the dark remained relatively constant from day 0 to day 15 and did not exceed food safety values of 200 mg kg−1 FW. A highly significant cultivar, light and cultivar × light (P < 0.01) interaction was recorded. Cultivar Kestrel was shown to be light‐sensitive with high rates of glycoalkaloid accumulation irrespective of light source, and cv Maris Piper was demonstrated to be light‐insensitive. In the majority of cultivars tested, maximal rates of glycoalkaloid accumulation were recorded following exposure of tubers to sodium or fluorescent light, and minimal rates of accumulation were recorded following exposure of tubers to mercury (MB/U and MBFR/U) illumination. In virtually all cases glycoalkaloid concentrations steadily increased with time during light exposure with no indication of cessation. In some instances the α‐chaconine/α‐solanine ratio decreased over 15 days of illumination (P < 0.05), indicating enhanced α‐solanine synthesis over that of α‐chaconine. The implications of these results in terms of consumer safety are discussed. © 1999 Society of Chemical Industry  相似文献   

4.
Individual tubers from mature plants of cultivars Pentland Dell and Estima were harvested from experimental plots in two successive years and analysed for α‐solanine, α‐chaconine and total glycoalkaloid concentration (α‐solanine and α‐chaconine combined) using high‐performance liquid chromatography. Mean tuber glycoalkaloid concentration per plant was strongly affected by genotype and was much higher in plants of Pentland Dell (10.0 and 16.3 mg per 100 g fresh weight in 1994 and 1995, respectively) than Estima (4.0 and 4.3 mg per 100 g fresh weight in 1994 and 1995, respectively). The variation between plants in mean tuber glycoalkaloid concentration, expressed as coefficient of variation, was similar for the two cultivars in both years. Variation within plants was higher for cultivar Pentland Dell than Estima for both years but it was statistically significant only in 1995. Tuber position within a plant had no effect on glycoalkaloid concentrations in tubers of similar size. An inverse relationship between total glycoalkaloid concentration and tuber fresh weight of individual tubers was found for both cultivars and small tubers of Pentland Dell (20–40 g fresh weight) exceeded the safety limit of 20 mg per 100 g fresh weight. The pattern of glycoalkaloid accumulation differed between genotypes and appeared related to tuber growth. The implications of these results in terms of food safety are discussed. © 1999 Society of Chemical Industry  相似文献   

5.
Potato (Solanum tuberosum L) tubers (cvs Pentland Dell and Record) were treated with the chlorophyll biosynthesis inhibitors 4-amino-5-fluoropentanoic acid (AFPA) and 3-amino-2,3-dihydrobenzoic acid (gabaculine), and subsequently exposed to daylight for up to 10 days prior to pigment and glyco-alkaloid analysis. AFPA inhibited the accumulation of total chlorophyll (Chl) by between 50 and 70% in both cultivars throughout the duration of light exposure. The synthesis of Chl b was inhibited by over 80% in both cultivars. Neither inhibitor had a significant effect on light-enhanced glycoalkaloid accumulation. It is concluded that there is no direct metabolic link between Chl and glycoalkaloid biosynthesis. © 1998 SCI.  相似文献   

6.
Six varieties of Solanum tuberosum L potato grown in the Bolivian highlands under drought stress, with and without irrigation, were analysed for their content of glycoalkaloids (GAs). The plant material consisted of three drought‐tolerant varieties from a local breeding programme (PROINPA), Potosina, Chapaquita and Pampeña, and three control cultivated varieties, Malcacho, Sani Imilla and Desiree, either susceptible or relatively tolerant to drought. α‐Solanine and α‐chaconine were quantified in both the peel and flesh of the tubers. A significant increase in GA concentration (α‐solanine + α‐chaconine) was observed under drought stress conditions in most varieties; average concentration increases of 43 and 50% were registered in the improved and control cultivars respectively. In all tested cultivars, however, the GA concentration remained lower than the recommended food safety level (200 mg kg−1 fresh tubers). It ranged from 52.4 to 100 mg kg−1 fresh tubers in the improved cultivars and from 55.6 to 122.3 mg kg−1 fresh tubers in the controls. In the improved and control varieties the α‐solanine content averaged 42.6 and 35.4% of the total potato GAs respectively and was not significantly affected by drought stress, except in Desiree. In all conditions the peel contained the greatest proportion of total GAs. The hybrid variety Pampeña (new drought‐tolerant variety) contained the lowest amounts of GAs, which were lower than those of the control varieties, with and without irrigation. © 2000 Society of Chemical Industry  相似文献   

7.
In 1986, potentially toxic levels of the glycoalkaloids α-solanine and α-chaconine were unexpectedly found in tubers of the established Swedish consumer potato variety Magnum Bonum, leading to the imposition of a conditional sales ban on such potatoes. The combined amounts of α-solanine and α-chaconine in more than 300 commercial lots of Magnum Bonum potatoes analysed as a consequence of the ban ranged from 61 to 665 mg kg?1 fresh weight with an average of 254 mg kg?1. Sixty-six percent of the samples exceeded a temporary maximum residue limit of 200 mg kg?1, 8% were above 400 mg kg?1. Peeling did not significantly remove the glycoalkaloids in tubers with a high content. The occasional glycoalkaloid elevation was initially attributed to the unusually cold and rainy conditions during the late part of the season in 1986, but subsequent investigations have failed to confirm this hypothesis. Varietal characteristics are likely to have been involved since most other common Swedish varieties seemed to have had normal glycoalkaloid levels in 1986. There were no indications of serious or widespread adverse health effects in consumers due to the high glycoalkaloid levels, although there was circumstantial evidence that a few cases of temporary gastrointestinal disturbances were caused by consumption of Magnum Bonum potatoes with glycoalkaloid concentrations in the range 310–1000 mg kg?1.  相似文献   

8.
Tubers from five potato cultivars were selected on the basis of their low, intermediate or high rates of glycoalkaloid synthesis in response to stresses such as light or cold storage temperatures. The tubers were subjected to a standard degree of damage sufficient to cause bruising but not severe damage such as cracking or splitting. Increases in glycoalkaloid levels in response to damage were observed in all cultivars. Importantly, the rates of glycoalkaloid synthesis in response to damage were in good agreement with cultivar response to light and cold temperature stress. The cultivars, Ailsa and Eden, exhibited a slower response than the higher synthesis rates observed in Pentland Dell or Brodick. The cultivar Torridon exhibited severe internal damage symptoms throughout the tuber as opposed to localised bruising observed in the other cultivars. The extensive cell death observed in the tubers of the cultivar Torridon severely curtailed glycoalkaloid and chlorogenic acid synthesis. The increased levels of glycoalkaloids in response to bruising damage ranged from approximately 27% (Ailsa, Torridon) to 130% for the cultivar Brodick. Chlorogenic acid levels increased in two cultivars (Brodick and Torridon) but not in the others, Ailsa, Eden and Pentland Dell. The α-chaconine/α-solanine ratios observed within the five cultivars were in good agreement with previous research. The consistency across years is notable, indicating a strong relationship in the synthesis of the two glycoalkaloids. The results are discussed in terms of implications for the potato industry, for the retail trade and also for selection within potato breeding programmes. © 1998 SCI.  相似文献   

9.
The composition of aerial and subterranean tubers of two potato genotypes cvs Desiree (red skin) and Epicure (white skin) was compared immediately after harvest using a range of analytical methods. Irrespective of genotype, aspartic acid, arginine, glycine, glutamic acid, histidine, leucine, serine, threonine and total amino acid concentrations were significantly higher (P<0·05) in aerial compared with subterranean tuber tissue. Significant increases (P<0·05) in valine in aerial tubers, but no significant differences in alanine, tyrosine and iso-leucine, when compared with subterranean tubers of cv Desiree, were found. In cv Epicure, alanine, tyrosine and iso-leucine were significantly higher in aerial tubers (P<0·05); however, no significant differences in valine were recorded. There was no significant increases in lysine and phenylalanine between tuber types. Regardless of genotype α-solanine, α-chaconine, chlorogenic acid, chlorophyll and crude protein concentrations were significantly higher in aerial tubers compared with subterranean ones (P<0·01). No significant increases in total lipids between tuber types were found. In cv Desiree, ascorbic acid content was not significantly different between aerial and subterranean tuber tissue, but in cv Epicure concentrations were significantly higher (P<0·01) in aerial tubers. Starch concentrations were significantly higher in subterranean tubers of both cultivars (P<0·05). Sugar content was significantly higher in aerial tubers of cv Epicure (P<0·01), but not significantly different between aerial and subterranean tubers of cv Desiree. Regardless of genotype, phosphorus, magnesium, potassium, zinc, manganese and sodium concentrations were significantly higher (P<0·05) in aerial tubers. Iron and copper concentrations were significantly higher in aerial tubers of cv Desiree (P<0·01), but significantly less in cv Epicure compared with subterranean tubers (P<0·01, P<0·05). Calcium concentrations were not significantly different between aerial and subterranean tubers of cv Desiree, but significantly higher in aerial tuber tissue of cv Epicure (P<0·01). Total gross energy (mJ kg−1 FW) was higher in aerial tubers of cv Desiree compared with subterranean tubers (P>0·05), but not significantly different between aerial and subterranean tubers of cv Epicure. The potential applications of aerial tubers for industrial purposes are discussed. © 1997 SCI.  相似文献   

10.
An improved high-performance liquid chromatography (h.p.l.c.) procedure for determination of glycoalkaloid levels in potato tubers has been developed in which Sep-Pak cartridges replace the commonly used alkaline precipitation for clean-up of tuber extracts. Glycoalkaloids are extracted from fresh tuber tissue into an aqueous medium, the extract is submitted to clean-up and α-solanine and α-chaconine are quantitatively separated on a reversed phase column with ethanolamine modifier added to the mobile phase. Potato tubers were comparatively analysed for their glycoalkaloid content by this and two other methods: a recently developed immunoassay (ELISA) and a colorimetric procedure representing the traditional chemical approach. Agreement between the h.p.l.c. and the other methods was good.  相似文献   

11.
The effects of low temperature and of combined stresses, cool temperature and waterlogging and also warm temperature and drought, on potato tuber glycoalkaloid levels were investigated, with emphasis on comparison of tubers of similar size. The early maturing cultivars Home Guard, Rocket and British Queen were grown under favourable controlled environment conditions (18/14 °C day/night temperature, 14 h photoperiod) until the imposition of treatments after the start of tuber initiation. Transfer to low temperature (12/9 °C) did not increase total glycoalkaloid concentration in any of the three cultivars. However, waterlogging at 12/9 °C increased total glycoalkaloid concentration during the later stages of development of British Queen. Drought stress at 24/18 °C also increased total glycoalkaloid concentration in British Queen, although the response varied between individual tubers of similar size. Total glycoalkaloid concentrations in tubers of Rocket were not affected by the combined stress treatments, and any effects on Home Guard were very much less than on British Queen. © 1999 Society of Chemical Industry  相似文献   

12.
Potato tubers of four varieties (Brodick, King Edward, Pentland Dell and Record) were stored under commercial conditions and exposed to light for up to 10 days after 0, 10, 20 and 30 weeks. These were analysed for photosynthetic pigment and glycoalkaloid content. There was no significant alteration in either tuber chlorophyll or glycoalkaloid content during dark storage. All four varieties greened in response to light exposure, but only three exhibited a significant increase in glycoalkaloid concentrations during this exposure. Storage duration did not significantly affect pigment accumulation. However, there was a marked effect of storage on the extent of glycoalkaloid accumulation. Tubers of all four varieties stored for more than 10 weeks did not accumulate glycoalkaloids to the same extent as fresh tubers. Indeed, Brodick and Record did not accumulate any glycoalkaloids in response to light after 30 weeks of storage. A number of artificial neural network models of the results were produced. These accurately modelled cultivars individually, but a model encompassing all the data was not successful at predicting cultivar differences. © 1999 Society of Chemical Industry  相似文献   

13.
The effect of a range of concentrations of α-tocopherol in the initial yolk on the subsequent levels of this vitamin in the tissues of the newly hatched chick was investigated. Four batches of fertile eggs (Ross 1 broiler-breeder type) with mean yolk α-tocopherol concentrations (μg g−1 yolk) of 60·8, 155·3, 272·2 and 376·6 were incubated and the levels of the vitamin in the liver, brain, heart and kidney of the resultant chicks were measured. The liver of the day-old chick contained far higher levels of the vitamin than were found in the other tissues studied. The concentration of α-tocopherol in the liver was directly proportional to the initial level of this vitamin in the yolk. The concentrations of α-tocopherol in the brain were only about 1% of the corresponding liver values but were also directly proportional to the levels initially present in the yolk. The concentrations of α-tocopherol exhibited by the heart and kidney were affected by the initial yolk values but the response was not linear over the range of yolk α-tocopherol concentrations studied. The results indicate that the initial concentration of α-tocopherol in the yolk has a profound effect on the subsequent levels of this vitamin in the tissues of the chick. In a separate experiment, the changes in the concentration of α-tocopherol in the liver were studied over the first 9 days after hatching. The vitamin was found to be rapidly depleted from the liver after hatching. © 1997 SCI.  相似文献   

14.
Tubers from six cultivars selected on the basis of their rates of glycoalkaloid accumulation in response to light exposure were stored at 10, 7 and 4°C. After 9 weeks at 10°C a subset from each cultivar was removed and subsequently stored at lower temperatures. Samples were removed after 9, 18 and 24 weeks storage and analysed for their glycoalkaloid content. At all temperatures the rate of glycoalkaloid accumulation was independent of the level found at harvest and significant interactions were found between cultivar and temperature. The highest rates of accumulation were seen in tubers from the cultivars Brodick and Pentland Crown stored at 4°C. During the first 9 weeks of storage at this temperature the glycoalkaloid content of these two cultivars increased by 7·4 and 19·1 mg per 100 g fresh weight respectively and thereafter remained constant. At 7°C glycoalkaloid content tended to increase more rapidly than at 10°C with again the greatest increases being found for Brodick and Pentland Crown. In the case of the former glycoalkaloid content increased linearly during the 24 weeks of the experiment but the glycoalkaloid content of Pentland Crown tubers stored at 7°C increased rapidly in the first 9 weeks and thereafter increased more slowly, reaching a final value which exceeded the recommended maximum glycoalkaloid concentration for human consumption by 50%. Cultivars which did not accumulate glycoalkaloids rapidly in response to light exposure were the most stable and least sensitive to storage temperature. Tubers transferred to colder conditions nine weeks after storage at 10°C did not accumulate glycoalkaloids at a similar rate to those placed in similar conditions soon after harvest. © 1997 SCI  相似文献   

15.
Starch, potato protein concentrate, and potato pulp were produced in order to determine the fate of endogenous toxic glycoalkaloids during potato processing. Potato protein concentrate was precipitated from potato fruit water using acid and heat. Glycoalkaloid concentrations were determined using matrix- assisted laser desorption/ionization mass spectrometry. No correlation was observed between tuber protein concentration and yield of potato protein concentrate (r = 0.257). Glycoalkaloids could not be detected in starch extracted from tubers with a glycoalkaloid concentration of 6.6 mg/i 00 g (fwb). Dry potato protein concentrate and dry potato pulp produced from the same tubers contained 60 and 50 mg glycoalkaloid/100 g, respectively. the apparent partitioning of glycoalkaloids into the protein concentrate and pulp indicates toxicity might be a concern for these products, given that a maximum acceptable level of 20 mg glycoalkaloid/100 g is often cited for tubers.  相似文献   

16.
Changes in contents of protein, starch, ash, l-ascorbic acid, and glycoalkaloids in tubers of 15 clones of cultivar Irga transformed with viral genome sequences in order to improve their resistance to a necrotic strain of potato virus Y (PVYN) were investigated. The influence of modification type and year of cultivation on the contents of all chemical compounds examined for particular modified clones appeared to be irregular over the 3-year period of examination, and the clone of the best and stable content of chemical compounds was not found. Stable tendencies in the chemical compounds of tubers composed into groups and subgroups of clones representing the same modification type were not confirmed either. An essential stable decrease in glycoalkaloid content and an increase in starch content (compared with parental cultivar Irga) were found in almost all genetically modified clones. Glycoalkaloid content in green tubers of modified clones was usually (except three clones) higher than this for parental cultivar Irga. Correlation between glycoalkaloid content and tuber size for all, normal and green tubers of selected clones and parental cultivar Irga was examined as well.  相似文献   

17.
Samples of Swedish domestic early potatoes were collected from wholesalers and analysed for their content of glycoalkaloids (GA), α-solanine and α- chaconine, using a modified HPLC procedure. The varieties included were, in order of increasing GA content; Maris Bard, Ukama, Pro vita, Evergood Eldorado, Maria, Early Puritan, Silla and Ulster Chieftain. The average total GA content (α-solanine and α-chaconine combined) for the different varieties ranged from 51 to 221 mg kg?1 fresh weight. α-Solanine constituted on average between 35 and 41% of the GA detected. The GA concentrations in individual samples were in the range 31-344 mg kg?1. The variety Ulster Chieftain accounted for 88% of the samples above 200 mg kg ?1. The results obtained with tubers grown experimentally in field trials in two different years were consistent with the findings for commercially grown potatoes in terms of GA content rank among varieties.  相似文献   

18.
The use of gamma irradiation to control sprouting and increase the length of storage time of potatoes has been proposed as an alternative to cold storage or the use of chemical sprout suppressants. Indeed, it is applied on a commercial-scale to potatoes in Japan. This research reports on the effects of different levels of gamma irradiation on seven potato cultivars in relation to chlorophyll and glycoalkaloid synthesis on subsequent exposure to light after a period of storage. There were significant genotype differences between cultivars in their response to gamma irradiation, with some cultivars exhibiting dramatically reduced levels of glycoalkaloid synthesis compared with others. Also, cultivars responded differently to variable irradiation levels. The implications of the results are discussed in relation to public health concerns and selection within potato breeding programmes. © 1997 SCI.  相似文献   

19.
With the increasing production and consumption of potato and its products, glycoalkaloid (GA) formation and toxicity are likely to become an important focus for food safety researchers and public health agencies. Not only the presence of GA, particularly in the form of α‐solanine and α‐chaconine, but also the changes occurring as a result of various post‐harvest handling practices and storage, are critical issues influencing the quality of stored potatoes. Studies on various factors (pre‐harvest, during harvest and post‐harvest) affecting GA have been carried out from time to time, but it is difficult to compare the results of one study with another due to wide variation in the parameters chosen. This review aims to develop a clear understanding of these issues. Published information on the types of GA, their effects on health, their typical concentrations in potatoes, their formation mechanisms, and how their levels can be controlled by following appropriate post harvest practices and storage regimes are critically analysed. The levels of GA in potato can be controlled effectively by adopting appropriate post‐harvest practices. Further studies are necessary, however, to investigate best practices, which either check completely or retard substantially their formation. Copyright © 2008 Society of Chemical Industry  相似文献   

20.
Twenty‐four Large White × Landrace pigs were individually fed, from 50 to 90 kg live weight, either a control (CONT) diet containing palm oil or one of three diets based on full‐fat rapeseed (250 g kg−1) (diets RD). The RD diets were supplemented with 0, 200 or 500 mg DL ‐α‐tocopherol acetate (ATA) kg−1 diet (diets RD0, RD200 and RD500 respectively). Diets were formulated to be isonitrogenous and isocaloric. Daily live weight gain was significantly increased (p < 0.01) in pigs fed diet RD500. Plasma AT concentration was significantly increased by dietary supplementation with 200 mg ATA kg−1 but showed no further significant increase by supplementation with 500 mg ATA kg−1. At slaughter, after 45 days, carcass weights were increased for the RD500 group but dressing percentage was unaffected. ATA supplementation significantly reduced drip loss on days 4 and 5–7 in fresh muscle and on days 1 and 4 in frozen muscle. The concentrations of calcium, sodium and potassium in drip loss fluid collected on days 1 and 4 from fresh muscle were not significantly affected by treatment or by time of collection and did not suggest any change in the relative contribution of intra‐ and extracellular fluid to total drip loss. Plasma enzyme activities related to tissue damage (creatine kinase, alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase) were not influenced by dietary treatments. © 2000 Society of Chemical Industry  相似文献   

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