Composition and stability of anthocyanins in blue-grained wheat

Wheat grain is recognized as a good source of potentially health-enhancing components such as dietary fiber, phenolics, tocopherols, and carotenoids. Anthocyanins, another group of bioactive compounds, are found in blue and purple wheat grains. In the present study, a blue aleurone spring wheat line "Purendo 38" with relatively high content of total anthocyanins was used to investigate the composition and stability of anthocyanins over three crop years. Commercial cultivars of purple (Konini) and red (Katepwa) wheats were included in the study. Separation of anthocyanins by high-performance liquid chromatography (HPLC) showed that each wheat had a distinct anthocyanin profile. Four major anthocyanins were separated from blue wheat extracts as compared to five anthocyanins in purple wheat. Cyanidin 3-glucoside was the predominant anthocyanin in purple wheat, whereas it was the second major anthocyanin in blue wheat. The predominant anthocyanin in blue wheat, making up approximately 41% of the total anthocyanin content, remains to be structurally unidentified. Blue wheat anthocyanins were thermally most stable at pH 1. Their degradation was slightly lower at pH 3 as compared to pH 5. Increasing the temperature from 65 to 95 degrees C increased degradation of blue wheat anthocyanins. Addition of SO(2) during heating of blue wheat had a stabilizing effect on anthocyanin pigments. The optimal SO(2) concentrations were 500-1000 ppm for whole meals and 1000-3000 ppm for isolated anthocyanins. Further studies are underway to identify and verify individual anthocyanins in blue wheat and their potential end uses.     

Anthocyanin composition in black, blue, pink, purple, and red cereal grains

Anthocyanin pigments from a wide variety of edible and ornamental black, blue, pink, purple, red, and white wheat, barley, corn, rice, and wild rice were identified and quantified to evaluate their potential as natural colorants or functional food ingredients. The total anthocyanin contents varied significantly and exhibited a range of 7-3276 microg/g. Some grains, such as red rice and black rice, contained a limited number of pigments, whereas others, such as blue, pink, purple, and red corns, had complex anthocyanin profiles. Of the 42 anthocyanin compounds observed, 9 were characterized by comparison of the spectroscopic and chromatographic properties with those of authentic standards. The remaining compounds were tentatively identified on the basis of spectroscopic properties and electrospray ionization mass spectra. The most abundant anthocyanins were cyanidin 3-glucoside in black and red rices and in blue, purple, and red corns, pelargonidin 3-glucoside in pink corn, and delphinidin 3-glucoside in blue wheat.     

Phytochemical profile of main antioxidants in different fractions of purple and blue wheat, and black barley

Two pigmented wheat genotypes (blue and purple) and two black barley genotypes were fractionated in bran and flour fractions, examined, and compared for their free radical scavenging properties against 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation (Trolox equivalent antioxidant capacity, TEAC), ferric reducing antioxidant power (FRAP), total phenolic content (TPC), phenolic acid composition, carotenoid composition, and total anthocyanin content. The results showed that fractionation has a significant influence on the antioxidant properties, TPC, anthocyanin and carotenoid contents, and phenolic acid composition. Bran fractions had the greatest antioxidant activities (1.9-2.3 mmol TEAC/100 g) in all four grain genotypes and were 3-5-fold higher than the respective flour fractions (0.4-0.7 mmol TEAC/100 g). Ferulic acid was the predominant phenolic acid in wheat genotypes (bran fractions) while p-coumaric acid was the predominant phenolic acid in the bran fractions of barley genotypes. High-performance liquid chromatography analysis detected the presence of lutein and zeaxanthin in all fractions with different distribution patterns within the genotypes. The highest contents of anthocyanins were found in the middlings of black barley genotypes or in the shorts of blue and purple wheat. These data suggest the possibility to improve the antioxidant release from cereal-based food through selection of postharvest treatments.     

Use of Pigmented Maize in Both Conventional Dry‐Grind and Modified Processes Using Granular Starch Hydrolyzing Enzyme

In the dry‐grind ethanol process, distillers dried grains with solubles (DDGS) is the main coproduct, which is primarily used as an ingredient in ruminant animal diets. Increasing the value of DDGS will improve the profitability of the dry‐grind ethanol process. One way to increase DDGS value is to use pigmented maize as the feedstock for ethanol production. Pigmented maize is rich in anthocyanin content, and the anthocyanin imparts red, blue, and purple color to the grain. It is reported that anthocyanin would be absorbed by yeast cell walls during the fermentation process. The effects of anthocyanin on fermentation characteristics in the dry‐grind process are not known. In this study, the effects of anthocyanin in conventional (conventional starch hydrolyzing enzymes) and modified (granular starch hydrolyzing enzymes [GSHE]) dry‐grind processes were evaluated. The modified process using GSHE replaced high‐temperature liquefaction. The ethanol conversion efficiencies of pigmented maize were comparable to that of yellow dent corn in both conventional (78.4 ± 0.5% for blue maize, 74.3 ± 0.4% for red maize, 81.2 ± 1.0% for purple maize, and 75.1 ± 0.2% for yellow dent corn) and modified dry‐grind processes using GSHE (83.8 ± 0.8% for blue maize, 81.1 ± 0.3% for red maize, 93.5 ± 0.8% for purple maize, and 85.6 ± 0.1% for yellow dent corn). Total anthocyanin content in DDGS from the modified process was 1.4, 1.9, and 2.4 times of that from the conventional process for purple, red, and blue maize samples, respectively. These results indicated that pigmented maize rich in anthocyanin did not negatively affect the fermentation characteristics of the dry‐grind process and that there was a potential to use pigmented maize in the dry‐grind process, especially when using GSHE.     

A Rapid Method for Quantifying Total Anthocyanins in Blue Aleurone and Purple Pericarp Wheats

A simple, rapid method for determining total anthocyanins was developed for use in developing wheat cultivars with dark-blue grains. The method was evaluated as a screening test and for quantification of total anthocyanins in blue and purple wheats and related cereals. Wheat anthocyanins were significantly more extractable in ethanol or methanol than in water at different pH levels. A sample-to-solvent ratio of 1:8 at pH 1 and 25°C was used. Anthocyanin extracts of pigmented wheat and barley grains exhibited absorbance spectra similar to cyanidin 3-glucoside. The absorbance of anthocyanin extracts of 160 blue wheat experimental lines were significantly correlated with whole-grain Hunterlab color values. Total anthocyanins averaged 157 mg/kg in blue wheat whole meal and 104 mg/kg in purple wheat whole meal, whereas blue wheat bran contained 458 mg/kg as compared with 251 mg/kg in purple wheat bran.     

In‐Depth Study of Durum Wheat Grain Tissue Distribution at Milling

The starchy endosperm proportion in durum wheat grain and its ability to be isolated from the peripheral tissues appear as main intrinsic characteristics potentially related to the milling value but still difficult to assess. In this study, several durum wheat samples displaying distinct grading characteristics were analyzed and processed through a pilot mill. The histological composition of grains and milling fractions was monitored by using identified biochemical markers of each wheat grain tissue. Contrasted milling yields of semolina and flour were observed between samples, despite displaying a similar starchy endosperm proportion determined by hand dissection. These yields were related both to differences in the starchy endosperm extraction and to the presence of the aleurone layer, particularly its cellular content. Furthermore, two distinct types of fractionation behavior of the aleurone layer were distinguished depending on the wheat grain sample. Extraction of the envelopes and embryonic axis into semolina and flours were found negligible in comparison with the other tissues.     

Comparison of black,purple, and yellow barleys

Many barley landraces are purple-or black-seeded, but the chemical composition of these purple-and black- seeded barley is rarely examined. Therefore, studies were conducted to determine if the chemical composition of purple and black barleys differs from that of yellow barleys. Four sets of genetic materials were used for these studies: 96 doubled-haploid (DH) lines, 10 near-isogenic lines, 40 landraces, and four F3 bulks. The results showed that purple DH lines contained a similar amount of lignin as yellow DH lines and that anthocyanin-containing isogenic lines did not differ from anthocyanin-free lines in lignin content. Therefore, these results suggest that anthocyanin biosynthesis is independent of lignin biosynthesis in barley. The results also showed that black barley contained more protein and more lignin than yellow barley in two crosses and that among the 40 landraces studied, the three with the highest concentration of lignin happened to be black seeded. Lignin content was not associated with seed weight except in defective endosperm lines. The presence of pigments and a relatively high concentration of lignin might help reduce the level of kernel blight severity in black barley. More studies are needed to determine the chemical composition and pest resistance associated with purple and black barleys.     

Anthocyanin Content and Composition in Winter Blue Barley Cultivars and Lines

This study focuses on the examination of the total anthocyanin content (TAC) and spectrum of winter barley cultivars with blue caryopsis. Preparation of grain samples was simplified, and extraction was performed with 85% methanol acidified by 1% trifluoroacetic acid. Compared with our previous tests performed with 1% hydrochloric acid in aqueous methanol, the extraction process resulted in higher total anthocyanin content with more acylated derivatives. The TAC measured by spectrophotometry varied in two blue Hungarian cultivars and two lines from 46.9 to 84.4 mg/kg. The anthocyanin spectrum was analyzed by electrospray ionization tandem mass spectrometry. The predominant anthocyanins were delphinidin‐3‐malonylglucoside and cyanidin‐3‐malonylglucoside, followed by delphinidin‐3‐glucoside and cyanidin‐3‐glucoside. The caryopsis retains the anthocyanins in long‐term storage. The TAC values of the crops over the last 10 years were definable retroactively. The relative abundance of the main anthocyanin components in grains of different harvest years (2000 and 2010) was similar. Statistical analysis revealed a relatively strong negative correlation (r = –0.7439, P < 0.05) between two variables: TAC and rainfall during the grain‐ripening period.     

Grain and Nutritional Quality Traits of Southwestern U.S. Blue Maize Landraces

Anthocyanin‐rich Southwestern blue maize (Zea mays L.) landraces are receiving interest as functional foods, and commercial production is increasing. We determined variation in kernel color, anthocyanin content, texture, and selected compositional traits of representative varieties. In 2013, eight varieties were grown at four locations in New Mexico. Total kernel anthocyanin content (TAC) and component pigments were measured with spectrophotometry and HPLC, respectively. Oil, protein, starch, and kernel density were determined using NIR spectroscopy and amino acid concentrations using wet chemistry. An average of 49.6 mg/100 g of TAC with a range of 17.6–65.1 mg/100 g was observed. Cyanidin and pelargonidin were major components, and peonidin and succinyl 3‐glucoside were minor components. Low levels of disuccinyl glucoside were detected. Blue kernels were higher in anthocyanin than purple or red kernels. Floury kernels displayed the highest protein and oil contents and the lowest starch content and kernel density. The highest starch and kernel density levels were observed in small flint/dent and pop‐flint/dent kernels. Amino acid content was variable across genotypes and locations.     

Comparative Studies on Composition and Distribution of Phenolic Acids in Cereal Grain Botanical Fractions

The phenolic acid composition and concentration of four manually separated fractions (pericarp, aleurone layer, germ, and endosperm fractions) as well as whole grains of yellow corn, wheat, barley, and oats were analyzed by HPLC‐MS/MS following microwave‐assisted alkaline aqueous extraction. Phenolic acid compositions in whole grains and their fractions were similar, with minor differences among the grain fractions. Significant differences (P < 0.05), however, were observed in phenolic acid concentrations among cereal types, within cereal varieties, and among grain fractions, with yellow corn exhibiting the highest values. The concentrations of p‐coumaric and syringic acid in the pericarp were 10‐ to 15‐fold and 6‐ to 10‐fold higher, respectively, in yellow corn than in wheat, barley, and oats. In the aleurone layer, sinapic and vanillic acids in yellow corn were about 8‐ and 30‐fold more than in wheat. The germ fraction of wheat had 1.8 times more syringic acid than yellow corn germ. Grain fractions, excluding endosperm, had enhanced levels of phenolic acids compared with whole grain. Sinapic acid was more concentrated in the pericarp and germ of wheat, whereas isoferulic acid was concentrated in the germ of purple barley. Syringic and vanillic acids were concentrated in the pericarp and sinapic acid in the aleurone layer of yellow corn. These findings are important in understanding the composition and distribution of phenolic acids, and they act as a guide in identification of grain fractions for use as food ingredients. In addition, yellow corn fractions (aleurone and pericarp) may be potential alternative phenolic‐rich functional food ingredients in grain‐based food products.     

Differences in the Aleurone Layer Fate Between Hard and Soft Common Wheats at Grain Milling

In the milling process, efficient separation between the starchy endosperm and the other grain tissues is a key parameter estimated by ash measurement. Because this separation occurs near the aleurone layer interface, better understanding of this tissue fractionation is critical for a better analysis of the wheat milling behavior. Samples from hard and soft common wheat cultivars that had the same protein content were processed on a pilot mill, and whole grain meals or flour streams were analyzed for ash content. The para‐coumaric acid (p‐CA) and phytic acid flour contents were compared with ash measurement and used as markers of the aleurone cell walls or aleurone cell content, respectively. A greater amount of phytic acid in hard wheat flour compared with soft wheat flour was found and reveals a distinct milling behavior between those wheat classes, mainly at the breaking step. Therefore simple ash content measurement is not sufficient to analyze flour purity. At the reduction stage, quantity of phytic acid increases with the other markers and may result from the overall mechanical resistance of the aleurone tissue. As a consequence, wheat hardness not only determines grain milling behavior but also affects flour composition.     

Relationship between phenolic compounds, anthocyanins content and antioxidant activity in colored barley germplasm

Barley and its products are good sources of antioxidants. This experiment was conducted to examine the classification and concentration of phenolic compounds, proanthocyanidins, and anthocyanins in 127 lines of colored barley. Their relationship with 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was also examined. Barley was placed into seven groups using the colorimeter: hulled (black 1, black 2, black 3, and purple) and unhulled (black, blue, and purple). The contents of phenolic compounds and anthocyanins were analyzed by using HPLC. The average content of phenolic compounds in unhulled barley groups (268.6 microg/g) was higher than that in hulled (207.0 microg/g) (P > 0.05). The proanthocyanidins content was determined by modified vanillin assay. The average content of proanthocyanidins was significantly higher in purple and blue barley groups compared with black (P < 0.05). The content of anthocyanins varied from 13.0 to 1037.8 microg/g. Purple and blue barley groups contained higher average contents of anthocyanins than black (P < 0.05). The most common anthocyanin in the purple barley groups was cyanidin 3-glucoside, whereas delphinidin 3-glucoside was the most abundant anthocyanin in the blue and black groups. In colored barley, DPPH radical scavenging activity had high positive correlation to the content of phenolic compounds and proanthocyanidins.     

Plasma and urine responses are lower for acylated vs nonacylated anthocyanins from raw and cooked purple carrots

The bioavailability of acylated vs nonacylated anthocyanins and the effect of cooking and dose on the comparative bioavailability were investigated in a clinical feeding study using purple carrots as the anthocyanin source. Treatments were purple carrots as follows: 250 g raw (463 micromol of anthocyanins: 400 micromol acylated, 63 micromol nonacylated), 250 g cooked (357 micromol of anthocyanins: 308.5 micromol acylated, 48.5 micromol nonacylated), and 500 g cooked (714 micromol of anthocyanins: 617 micromol acylated, 97 micromol nonacylated). Four of the five carrot anthocyanins were found intact in plasma by 30 min after carrot consumption and peaked between 1.5 and 2.5 h. Acylation of anthocyanins resulted in an 11-14-fold decrease in anthocyanin recovery in urine and an 8-10-fold decrease in anthocyanin recovery in plasma. Cooking increased the recovery of nonacylated anthocyanins but not acylated anthocyanins. Large dose size significantly reduced recovery of both acylated and nonacylated anthocyanins, suggesting saturation of absorption mechanisms.     

Comparative evaluation of the antioxidant potential of infant cereals produced from purple wheat and red rice grains and LC-MS analysis of their anthocyanins

Cellular oxidative damage by endogenous and exogenous sources of free radicals and reactive oxygen species is a particular threat in infants. Antioxidant protection is normally achieved through a balance between pro-oxidants and endogenous and/or dietary antioxidants. Comprehensive research is required on optimization to achieve good antioxidant protection through infant foods, in particular, the commercially available infant cereals. This study therefore investigated the properties of whole purple wheat, unpolished red rice, and partially polished red rice before and after processing to produce infant cereals. Total phenolic content (TPC), total anthocyanin content (TAC), oxygen radical absorbance capacity (ORAC), individual anthocyanin components, and cellular antioxidant activity were measured. Home-made and laboratory-made pigmented infant cereals differed in that the latter required longer exposure to higher temperature and enzymatic hydrolysis. Home-made and laboratory-made unpolished red rice infant cereals showed higher total phenolic contents and peroxyl radical scavenging activity than home-made and laboratory-made purple wheat infant cereals; however, the latter had higher TAC. Pigmented infant cereals generally had higher TPC, TAC, and ORAC than the commercial ones (p < 0.05). Anthocyanins were identified in whole purple wheat, but they were not detected in unpolished red rice. C-Glycosyl apigenin was found in both whole purple wheat and unpolished red rice. Processing significantly decreased anthocyanin and C-glycosyl apigenin contents (p < 0.05). Purple wheat infant cereals had higher cellular antioxidant activity than unpolished red rice ones (p < 0.05). Whole purple wheat infant cereals showed higher antioxidant activity than the commercial infant cereal, suggesting a possibility of improving infant antioxidant status by incorporating this grain in their diet.     

花青素积累与谷子低温胁迫响应的关系

为探究花青素积累与谷子低温胁迫响应的关系,本研究以绿叶和富含花青素的紫叶谷子品种为材料,通过对不同品种幼苗进行低温和常温(对照)处理,观察叶片中色素分布,测定叶片光合作用以及花青素、相对叶绿素、丙二醛(MDA)、脯氨酸(Pro)、可溶性糖(SS)含量。结果表明,低温诱导后紫叶品种叶片花青素主要分布在叶肉细胞和上下表皮细胞,而绿叶品种叶片中几乎无花青素积累。低温诱导后紫叶品种花青素变化明显,绿叶品种无明显变化;与对照相比,低温诱导12 d紫叶品种B13、B45、B55花青素含量分别增加了234%、226%、126%。低温诱导后,紫叶品种叶片的净光合速率(Pn)和相对叶绿素含量均降低,但SS和Pro含量显著升高,MDA含量无规律性变化。相关性分析结果表明,低温诱导12 d紫叶品种叶片花青素含量与相对叶绿素含量、Pn呈极显著负相关,而与Pro含量、SS含量呈极显著正相关,相对叶绿素含量与Pn呈正相关。由此可知,紫色谷子品种叶片花青素的合成可以被低温诱导,且与Pro、SS共同参与植物对低温胁迫的响应。本研究为探索紫叶谷子的抗寒性以及扩大其种植区域提供了理论依据。     

Automated Single‐Kernel Sorting to Select for Quality Traits in Wheat Breeding Lines

An automated single kernel near‐infrared system was used to select kernels to enhance the end‐use quality of hard red wheat breeder samples. Twenty breeding populations and advanced lines were sorted for hardness index, protein content, and kernel color. To determine whether the phenotypic sorting was based upon genetic or environmental differences, the progeny of the unsorted control and sorted samples were planted at two locations two years later to determine whether differences in the sorted samples were transmitted to the progeny (e.g., based on genetic differences). The average hardness index of the harvested wheat samples for segregating populations improved significantly by seven hardness units. For the advanced lines, hardness index was not affected by sorting, indicating little genetic variation within these lines. When sorting by protein content, a significant increase from 12.1 to 12.6% was observed at one location. Purity of the red samples was improved from ≈78% (unsorted control) to ≈92% (sorted samples), while the purity of the white samples improved from 22% (control) to ≈62% (sorted samples). Similar positive results were found for sorting red and blue kernel samples. Sorting for kernel hardness, color, and protein content is effective and based upon genetic variation.     

Effects of Allelic Variations in Wx‐1, Glu‐D1, Glu‐B3, and Pinb‐D1 Loci on Flour Characteristics and White Salted Noodle‐Making Quality of Wheat Flour

Doubled haploid wheat lines developed from a cross between a hard white winter wheat variety of normal starch endosperm and a waxy wheat variety were used to determine the effects of allelic variation in Wx‐1, Glu‐D1, Glu‐B3, and Pinb‐D1 loci on physiochemical properties of flour, noodle dough properties, and textural quality of cooked noodles. Milling yield, damaged starch content, protein content, and SDS sedimentation volume of flour were influenced the most by allelic composition of Pinb‐D1 loci, less by Wx‐1 loci, and least by Glu‐B3. Wheat lines carrying Pinb‐D1b or Glu‐B3h alleles exhibited higher milling yield and damaged starch content of flour than those with Pinb‐D1a and Glu‐B3d alleles. Wheat lines carrying the Pinb‐D1b allele were higher in protein content and SDS sedimentation volume than those carrying Pinb‐D1a. Mixograph water absorption was largely influenced by allelic composition of Wx‐1 loci, whereas mixograph mixing time and mixing tolerance were predominantly determined by allelic composition of Glu‐D1 loci. Amylose content and pasting properties of starch were mainly determined by allelic composition of Wx‐1 loci with little influence by allelic compositions of Glu‐D1, Glu‐B3, and Pinb‐D1 loci. Allelic composition of Wx‐1 loci contributed 53.4% of the variation in optimum water absorption of noodle dough and 26.7% of the variation in thickness of the noodle dough sheet. The variation of 7.8% in optimum water absorption of noodle dough was contributed by the allelic composition of Pinb‐D1 loci. Allelic composition of Wx‐1 loci was responsible for 73.2, 74.4, and 59.6% in the variation of hardness, springiness, and cohesiveness of cooked noodles, respectively. Cohesiveness of cooked noodles was also influenced by the allelic compositions of Glu‐B3 and Pinb‐D1 loci to a smaller extent.     

Calf thymus DNA-binding ability study of anthocyanins from purple sweet potatoes ( Ipomoea batatas L.)

A total of 10 anthocyanin compounds were identified from five purple sweet potato ( Ipomoea batatas L.) varieties, Qunzi, Zishu038, Ji18, Jingshu6, and Ziluolan, by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to assess their calf thymus DNA-binding ability in vitro. The interaction between anthocyanins and calf thymus DNA in Tris-HCl buffer solution (pH 6.9) was evaluated by fluorescence spectroscopy. Using ethidium bromide (EB) as a fluorescence probe, fluorescence quenching of the emission peak was seen in the DNA-EB system when anthocyanins were added, indicating that the anthocyanins bound with DNA. The acylated groups influenced the ability of the interaction with DNA. Anthocyanins from purple sweet potato with more acylated groups in sorphorose have a stronger binding ability with DNA.     

Functional and Nutritional Characteristics of Soft Wheat Grown in No‐Till and Conventional Cropping Systems

The effects of no‐till versus conventional farming practices were evaluated on soft wheat functional and nutritional characteristics, including kernel physical properties, whole wheat composition, antioxidant activity, and end‐product quality. Soft white winter wheat cultivar ORCF 102 was evaluated over a two‐year period from three long‐term replicated no‐till versus conventional tillage studies in Oregon. Wheat from the no‐till cropping systems generally had greater test weight, kernel diameter, and kernel weight and had softer kernels compared with wheat from the conventional tillage systems. Compared with the conventional systems, no‐till whole wheat flour had lower protein and SDS sedimentation volume. Ash content as well as most minerals measured (calcium, copper, iron, magnesium, and zinc), except for manganese and phosphorus, were generally slightly lower in no‐till than in conventional wheat. Whole wheat flour from the no‐till cropping systems generally had slightly lower total phenolic content and total antioxidant capacity. Milling properties, including flour yield, break flour yield, and mill score, were not affected by tillage systems. Refined flour from no‐till systems had lower protein, SDS sedimentation volume, and lactic acid and sucrose solvent retention capacities compared with flour from conventional tillage. No‐till wheat generally had greater sugar‐snap cookie diameter than conventionally tilled wheat. In conclusion, no‐till soft white winter wheat generally had slightly reduced nutritional properties (protein, ash, most minerals, and total antioxidant content) compared with wheat from conventionally tilled systems, and it had equivalent or sometimes superior functional properties for baking cookie‐type products.     

Soluble and bound phenolic compounds in different Bolivian purple corn ( Zea mays L.) cultivars

In nine Bolivian purple corn ( Zea mays L.) varieties the content of phenolic compounds as well as the anthocyanin composition has been determined. The phenotypes under investigation included four red and five blue varieties (Kulli, Ayzuma, Paru, Tuimuru, Oke, Huaca Songo, Colorado, Huillcaparu, and Checchi). In purple corn, phenolic compounds were highly concentrated in cell walls. Thus, simultaneous determination of soluble and bound-form phenolics is essential for analysis, extraction, and quantification. The present study reports the determination of soluble and insoluble-bound fraction of phenolic compounds by HPLC-DAD and HPLC-ESI-MS(n) in Bolivian purple corn varieties. Enzymatic, thermal, and alkaline hydrolyses were used to obtain the cell wall-linked phenolic compounds. Ferulic acid values ranged from 132.9 to 298.4 mg/100 g, and p-coumaric acid contents varied between 251.8 and 607.5 mg/100 g dry weight (DW), respectively, and were identified as the main nonanthocyanin phenolics. The total content of phenolic compounds ranged from 311.0 to 817.6 mg gallic acid equivalents (GAE)/100 g DW, and the percentage contribution of bound to total phenolics varied from 62.1 to 86.6%. The total monomeric anthocyanin content ranged from 1.9 to 71.7 mg cyanidin-3-glucoside equivalents/100 g DW. Anthocyanin profiles are almost the same among the different samples. Differences are observed only in the relative percentage of each anthocyanin. Cyanidin-3-glucoside and its malonated derivative were detected as major anthocyanins. Several dimalonylated monoglucosides of cyanidin, peonidin, and pelargonidin were present as minor constituents.