Flavonoid Content of U.S. Fruits, Vegetables, and Nuts

Abstract

Analytical data are reported for 20 flavonoids (as aglycones) determined for more than 60 fresh fruits, vegetables, and nuts collected from four regions across the United States at two times of the year. Sample collection was designed and implemented by the Nutrient Data Laboratory (USDA). Analyses of eight flavan-3-ols (catechin, catechin gallate, epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, gallocatechin, and gallocatechin gallate), six anthocyanins (cyanidin, delphinidin, malvidin, pelargonidin, peonidin, and petunidin), two flavanones (hesperetin and naringenin), two flavones (apigenin and luteolin), and two flavonols (myricetin and quercetin) were performed by the Food Composition Laboratory (USDA) using a hydrolysis method for the anthocyanidins, flavones, and flavonols and a direct extraction method for the flavan-3-ols and flavanones. Experimental results compare favorably (few statistically significant differences) to literature values in the flavonoid and proanthocyanidin database previously compiled by the Nutrient Data Laboratory. The results of this study showed a seasonal variation only for blueberries. This study also showed that the variation in the flavonoid content of foods, as purchased by the U.S. consumer, is very large. The relative standard deviation, averaged for each flavonoid in each food, was 168%.

Flavonoid intake and disability-adjusted life years due to Alzheimer’s and related dementias: a population-based study involving twenty-three developed countries

“…The determination of flavonoid content for each of these categories involved the use of information from the US Department of Agriculture (USDA) on the flavonoid content of selected foods (29) . Because some categories of minor grains and spices were not covered in the USDA publication, additional literature sources on food flavonoid content were used (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44) . The result was the creation of two flavonoid databases, one with USDAonly data as a source and one with USDA data supplemented with additional sources; the latter was used for all relevant figures and tables in the present study.…”

Profiling methods for the determination of phenolic compounds in foods and dietary supplements

“…Compromises in extraction and separation will affect both identification and quantification. Tables 1, 2, 3, 4 present 14 profiling methods for phenolic compounds that have been selected from the literature of the last 15 years [18][19][20][21][22][23][24][25][26][27][28][29][30][31]. This is not meant to be a comprehensive list.…”

“…In some cases, the methods were directed at a limited number of food materials, but could be readily modified for application to a greater breadth of materials than originally described [19,20,22,25,27]. In recent years, however, methods have appeared that were designed to cover a wide range of compounds in any type of food material [21,23,24,26,28,29] or as metabolite profiling methods [30,31]. For these methods, liquid chromatography (LC) is the method of choice for separation and diode array detection) and mass spectrometry (MS) detection are the detection methods of choice.…”

“…There are some exceptions, however. Methods are included that use multiple extractions [22], multiple chromatographic runs [28], and tandem MS (MS/MS) [30] or ion trap MS (IT/MS) [27,31] detection. Both of the latter methods are used in conjunction with collision-induced dissociation (CID).…”

“…Merken and Beecher [3] developed an LC-DAD method for the determination of 26 flavonoid aglycones in five phenolic subclasses based on a combination of acid hydrolysis (flavones, flavonols, and anthocyanidins) and direct extraction (flavan-3-ols and flavanones) with quantification using aglycones and some glycosidic flavanones. Harnly et al [28] used this method for the determination of 20 flavonoids in 59 fresh vegetables, fruits, and nuts sampled across the USA. A similar approach was used by Franke et al [36] for the determination of 12 polyphenols (in four phenolic subclasses) in Hawaiian fruits and vegetables.…”