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Antioxidant Capacity in Fruit and Vegetables -Cultivar Variation - Storage Conditions - Human Antioxidant Status

Nilsson, Jessica LU (2003)
Abstract (Swedish)
Popular Abstract in Swedish

De positiva hälsoeffekterna av ett högt intag av frukt och grönsaker har diskuterats intensivt under de senaste årtiondena. Flera befolkningsundersökningar har visat på samband mellan ett ökat intag av av frukt och grönsaker och en minskad risk för flera kroniska sjukdomar. Antioxidanter i vegetabilier anses vara en stor bidragande orsak till detta samband tack vare deras förmåga att ta hand om skadliga fria radikaler. Det finns därför ett stort behov att identifiera och mäta mängden av enskilda antioxidanter men också att finna och utveckla metoder som kan mäta de sammanlagda effekterna av antioxidanterna.



Syftena med studien var att utvärdera metoder som mäter den totala... (More)
Popular Abstract in Swedish

De positiva hälsoeffekterna av ett högt intag av frukt och grönsaker har diskuterats intensivt under de senaste årtiondena. Flera befolkningsundersökningar har visat på samband mellan ett ökat intag av av frukt och grönsaker och en minskad risk för flera kroniska sjukdomar. Antioxidanter i vegetabilier anses vara en stor bidragande orsak till detta samband tack vare deras förmåga att ta hand om skadliga fria radikaler. Det finns därför ett stort behov att identifiera och mäta mängden av enskilda antioxidanter men också att finna och utveckla metoder som kan mäta de sammanlagda effekterna av antioxidanterna.



Syftena med studien var att utvärdera metoder som mäter den totala antioxidativa kapaciteten (TAC) och att använda dessa för studier av frukt och grönsaker samt av human blodplasma. Variationen i TAC i olika bär och grönsaker undersöktes i relation till sortskillnader och efter lagring. Dessutom undersöktes effekten på TAC i human plasma efter intag av vegetabiliska måltider.



Två metoder för att mäta TAC jämfördes, den ena metoden (ABTS) mäter antioxidanternas radikalinfångande effekt och den andra (FRAP) mäter antioxidanternas förmåga att reducera trevärt järn till tvåvärt. Det fanns starka samband mellan mätvärden från de två metoderna i både vattenlösliga och vattenolösliga extrakt från jordgubbar och andra växter. TAC mättes också i sex antioxidativa substanser. Båda metoderna visade följande inbördes ordning i den antioxidativa kapaciteten: quercetin > ferulsyra > katekin > rutin > kaffesyra > Trolox > klorogensyra.



Den totala antioxidativa kapaciteten i växter hade följande rangordning: jordgubbar = grönkål >> blomkål > ärtor = vitkål. I både ärtor, jordgubbar och vitkål varierade TAC mellan olika sorter. I jordgubbar varierade halten av TAC, askorbinsyra, klorogensyra och ellagsyra tvåfalt medan TAC i ärtor varierade tvåfalt. I de vattenlösliga extrakten av ärtor och jordgubbar fanns det ett starkt samband med mängden askorbinsyra och i jordgubbar fanns det även ett samband mellan TAC i de vattenolösliga extrakten och ellagsyra. Askorbinsyra i ärtor bidrog till en stor del av det uppmätta TAC-värdet. Mogna jordgubbar hade högre nivåer av TAC och fenoliska antioxidanter än omogna och kyllagring av jordgubbar i tre dygn gav endast små förändringar av mängden antioxidanter. Vad gäller kålväxterna så observerades ingen skillnad i TAC mellan olika delar av plantan. Glukobrassicin, sinigrin och glukoiberin var de vanligast förekommande glukosinolaterna i både blomkål, vitkål och grönkål och för de flesta glukosinolaterna fanns skillnader mellan olika sorter av varje kålväxt. TAC i vitkål samvarierade med koncentrationen av flera glukosinolater.



Intag av en måltid bestående av 500 g ärtor eller blomkål höjde den totala antioxidativa kapaciteten i plasma på försökspersoner med 14% respektive 12%, medan en måltid bestående av 500 ml nyponsoppa eller svartvinbärsnektar inte visade någon effekt. Ökningen av urinsyra i plasma efter måltider med ärtor, blomkål eller jordgubbar visade samband med TAC-värdet i plasma. Man kunde dra slutsatsen att ändringar i halten urinsyra var en stor bidragande faktor till den uppmätta ökningen av TAC. Ökningen av TAC i plasma efter måltiderna var dock inte relaterad till TAC-värdena uppmätta i respektive måltid.



Studien visar att metoder för att mäta total antioxidativ kapacitet (TAC) i frukt och grönsaker är användbara för att utvärdera skillnader i antioxidativ potential mellan växtslag, växtsorter och odlingsperioder.. Fler undersökningar behövs som fokuserar på att utveckla specifika indikatorer på graden av oxidativ stress och antioxidantstatus i blodplasma hos konsumenten. (Less)
Abstract
The health-promoting effects of fruits and vegetables have been extensively discussed during the past decade since epidemiologic studies have shown relations between increased intake of fruit and vegetables and decreased incidences of several chronic diseases. It has been suggested that antioxidants are a main contributors to the observed effects, for example by acting as scavengers of free radicals. It is necessary to identify and quantify the antioxidants in plant food, but also to develop methods that measure the total effect of all antioxidants. The aims of the present study were to evaluate different methods of measuring the total antioxidant capacity (TAC), to apply them on plant foods and to human plasma. Variation in TAC of plants... (More)
The health-promoting effects of fruits and vegetables have been extensively discussed during the past decade since epidemiologic studies have shown relations between increased intake of fruit and vegetables and decreased incidences of several chronic diseases. It has been suggested that antioxidants are a main contributors to the observed effects, for example by acting as scavengers of free radicals. It is necessary to identify and quantify the antioxidants in plant food, but also to develop methods that measure the total effect of all antioxidants. The aims of the present study were to evaluate different methods of measuring the total antioxidant capacity (TAC), to apply them on plant foods and to human plasma. Variation in TAC of plants due to cultivar differences and storage was evaluated as well as the human antioxidant status after intake of plant food meals.



High correlations were obtained between TAC measured with two methods, a free radical scavenging method (ABTS) and a ferric reducing method (FRAP). Correlations were obtained both for strawberries and other plant extracts. The molar TAC response of six pure antioxidant substances were ranked in the following order by both methods: quercetin>ferulic acid>catechin>rutin>caffeic acid>Trolox=chlorogenic acid.



In the plant materials studied, the TAC was in the following order: strawberry=curly kale>>cauliflower>peas=white cabbage. TAC in peas, strawberries and white cabbage varied between varieties. In peas the variation was three-fold and in strawberries it was two-fold for TAC, ascorbic acid, chlorogenic acid and ellagic acid. TAC in water-soluble extracts of peas and strawberries correlated well with the ascorbic acid concentration, which also contributed a major part to TAC in peas. In strawberries the content of ellagic acid correlated with TAC in the water-insoluble extracts. Unripe strawberries had lower concentrations of TAC and phenolic antioxidants than riper berries. During cold storage for up to three days, relatively few changes in antioxidant concentration occurred. Regarding Brassica vegetables, TAC varied in cauliflowers cultivated in two consecutive years but there were no variations in TAC between the various parts of the plants. Glucobrassicin, sinigrin and glucoiberin were the most abundant glucosinolates, and for most glucosinolates differences were found in their contents between cultivars. TAC in the white cabbage samples was correlated to the content of several glucosinolates.



Intake of meals containing 500 g peas or cauliflower increased TAC in blood plasma by 14% and 12%, respectively, while 500 ml of rosehip or blackcurrant beverage did not affect the plasma TAC. The increase in uric acid after the intake of the pea and cauliflower meals was correlated with the plasma TAC, and uric acid was responsible for the major contribution to the measured increase in plasma TAC. The plasma levels of TAC were not related to TAC measured in the meals.



This study shows that methods of measuring TAC are valuable tools in revealing differences in antioxidant content between cultivars and cultivation periods of fruit and vegetables. Further investigations are, however, necessary to develop more selective indicators of antioxidant status in the blood plasma of the consumer. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Docent Dimberg, Lena, Department of Food Science, Swedish University of Agricultural Science, Uppsala, Sweden
organization
publishing date
type
Thesis
publication status
published
subject
keywords
human plasma antioxidants, Brassica, strawberry, pea, cultivar, ABTS, FRAP, Total antioxidant capacity, TAC, Food and drink technology, Livsmedelsteknik
pages
176 pages
publisher
Biomedical Nutrition, Lund University
defense location
Hall C, Center for Chemistry and Chemical Engineering, Lund Institute of Technology
defense date
2003-12-18 10:15
ISBN
91-7422-038-1
language
English
LU publication?
yes
id
99ca2a20-e9fb-46ee-a949-43c54ec24bf9 (old id 466521)
date added to LUP
2007-10-14 14:24:30
date last changed
2016-09-19 08:45:05
@misc{99ca2a20-e9fb-46ee-a949-43c54ec24bf9,
  abstract     = {The health-promoting effects of fruits and vegetables have been extensively discussed during the past decade since epidemiologic studies have shown relations between increased intake of fruit and vegetables and decreased incidences of several chronic diseases. It has been suggested that antioxidants are a main contributors to the observed effects, for example by acting as scavengers of free radicals. It is necessary to identify and quantify the antioxidants in plant food, but also to develop methods that measure the total effect of all antioxidants. The aims of the present study were to evaluate different methods of measuring the total antioxidant capacity (TAC), to apply them on plant foods and to human plasma. Variation in TAC of plants due to cultivar differences and storage was evaluated as well as the human antioxidant status after intake of plant food meals.<br/><br>
<br/><br>
High correlations were obtained between TAC measured with two methods, a free radical scavenging method (ABTS) and a ferric reducing method (FRAP). Correlations were obtained both for strawberries and other plant extracts. The molar TAC response of six pure antioxidant substances were ranked in the following order by both methods: quercetin&gt;ferulic acid&gt;catechin&gt;rutin&gt;caffeic acid&gt;Trolox=chlorogenic acid.<br/><br>
<br/><br>
In the plant materials studied, the TAC was in the following order: strawberry=curly kale&gt;&gt;cauliflower&gt;peas=white cabbage. TAC in peas, strawberries and white cabbage varied between varieties. In peas the variation was three-fold and in strawberries it was two-fold for TAC, ascorbic acid, chlorogenic acid and ellagic acid. TAC in water-soluble extracts of peas and strawberries correlated well with the ascorbic acid concentration, which also contributed a major part to TAC in peas. In strawberries the content of ellagic acid correlated with TAC in the water-insoluble extracts. Unripe strawberries had lower concentrations of TAC and phenolic antioxidants than riper berries. During cold storage for up to three days, relatively few changes in antioxidant concentration occurred. Regarding Brassica vegetables, TAC varied in cauliflowers cultivated in two consecutive years but there were no variations in TAC between the various parts of the plants. Glucobrassicin, sinigrin and glucoiberin were the most abundant glucosinolates, and for most glucosinolates differences were found in their contents between cultivars. TAC in the white cabbage samples was correlated to the content of several glucosinolates.<br/><br>
<br/><br>
Intake of meals containing 500 g peas or cauliflower increased TAC in blood plasma by 14% and 12%, respectively, while 500 ml of rosehip or blackcurrant beverage did not affect the plasma TAC. The increase in uric acid after the intake of the pea and cauliflower meals was correlated with the plasma TAC, and uric acid was responsible for the major contribution to the measured increase in plasma TAC. The plasma levels of TAC were not related to TAC measured in the meals.<br/><br>
<br/><br>
This study shows that methods of measuring TAC are valuable tools in revealing differences in antioxidant content between cultivars and cultivation periods of fruit and vegetables. Further investigations are, however, necessary to develop more selective indicators of antioxidant status in the blood plasma of the consumer.},
  author       = {Nilsson, Jessica},
  isbn         = {91-7422-038-1},
  keyword      = {human plasma antioxidants,Brassica,strawberry,pea,cultivar,ABTS,FRAP,Total antioxidant capacity,TAC,Food and drink technology,Livsmedelsteknik},
  language     = {eng},
  pages        = {176},
  publisher    = {ARRAY(0xa9c7660)},
  title        = {Antioxidant Capacity in Fruit and Vegetables -Cultivar Variation - Storage Conditions - Human Antioxidant Status},
  year         = {2003},
}