In vitro bioavailability of phenolic compounds from five cultivars of frozen sweet cherries (Prunus avium L.)

The bioavailability of phenolic compounds from five cultivars of frozen sweet cherries was assessed by a digestion process involving pepsin-HCl digestion (to simulate gastric digestion) and pancreatin digestion with bile salts (to simulate small intestine conditions) and dialyzed to assess serum- and colon-available fractions. After pepsin digestion, the % recovery of total phenolics, relative to the original starting material, increased, whereas the % anthocyanins did not change. Following pancreatic digestion and dialysis, the total phenolics in the IN (serum-available) fraction was about 26-30% and the OUT (colon-available) fraction was about 77-101%. The anthocyanin content in the IN fraction was 15-21%, and in the OUT fraction, it was 52-67%. Skeena, Lapins, and Sweetheart cultivars contained higher levels of total phenolics and anthocyanins, which resulted in higher concentrations of these compounds in the IN and OUT fractions. The potential bioavailability of phenolic compounds was also assessed in Bing and Lapins cultivars at three ripening stages. Immature cherries had higher % total phenolics in the IN fraction than mature or overmature cherries. However, immature cherries had the lowest concentrations of these compounds, making the actual bioavailable amounts of these compounds lower than for mature and overmature fruit. High-performance liquid chromatography analysis of Lapins cherries at three maturity stages confirmed the results obtained using spectrophotometric methods for total phenolics and anthocyanins.     

Quantitative analysis of aroma compounds in carrot (Daucus carota L.) cultivars by capillary gas chromatography using large-volume injection technique

Dynamic headspace sampling was used to collect aroma compounds from raw samples of four carrot (Daucus carota L.) cultivars (Brasilia, Duke, Fancy, and Cortez). The collected volatiles were analyzed by capillary GC-FID and GC-MS using large-volume cool on-column injection (LVI-COC). Of the 36 compounds identified, 6 had not been previously detected in carrots. Significant differences between the carrot cultivars were found for 31 of the identified volatiles as well as for total monoterpenes, sesquiterpenes, and total volatile content. Mono- and sesquiterpenes accounted for about 98% of the total volatile mass in all cultivars. LVI-COC injection was used to determine the loss of carrot volatiles during concentration of headspace samples under a stream of nitrogen. The loss among major monoterpenes in the concentrated samples varied from 16% for p-cymene to >40% for alpha-pinene as compared to nonconcentrated samples. The loss among high-boiling sesquiterpenes varied from not detectable (beta-caryophyllene, alpha-humulene, and caryophyllene oxide) to approximately 7% for (E)- and (Z)-gamma-bisabolene.     

HPLC determination of chlorophyll and carotenoid pigments in processed green pea cultivars (Pisum sativum L.)

Chlorophyll and carotenoid pigments from six cultivars of processed green peas (Avola, Tristar, Rampart, Turon, Bella, and Greenshaft) were extracted with 100% acetone and analyzed by reversed-phase HPLC. A total of 17 pigments were identified in the pea cultivars including 8 xanthophylls ((all-E)-neoxanthin, (9'Z)-neoxanthin, (all-E)-violaxanthin, neochrome, (all-E)-lutein epoxide, (all-E)-lutein, neolutein B, neolutein A), 4 chlorophyll b related compounds (chlorophyll b derivative, chlorophyll b, chlorophyll b', and pheophytin b), 4 chlorophyll a related compounds (chlorophyll a derivative, chlorophyll a, chlorophyll a', and pheophytin a), and (all-E)-beta-carotene. The efficiency of different extraction procedures using 100% acetone showed that initial extraction followed by three reextractions without holding time between gave a higher extraction yield than no reextraction and 30 or 60 min holding time. All six cultivars contained the same pigments, but the concentration of each pigment varied significantly. On average of the two years, the chlorophyll a concentration varied from 4800 to 7300 microg/100 g fresh weight, the chlorophyll b concentration from 2100 to 2800 microg/100 g fresh weight, the (all-E)-lutein concentration from 1200 to 1900 microg/100 g fresh weight, and the (all-E)-beta-carotene concentration from 300 to 490 microg/100 g fresh weight in the processed pea cultivars. These differences in pigment concentration between the investigated cultivars are discussed in relation to maturity, product color and nutritional quality.     

Dietary fiber content and associated antioxidant compounds in Roselle flower (Hibiscus sabdariffa L.) beverage

The beverage of Hibiscus sabdariffa flowers is widely consumed in Mexico. Polyphenols contained in plant foods are frequently associated with dietary fiber. The aim of this work is to quantify the dietary fiber, associated polyphenols, and antioxidant capacity of the Roselle flower and the beverage traditionally prepared from it and its contribution to the Mexican diet. Roselle flower contained dietary fiber as the largest component (33.9%) and was rich in phenolic compounds (6.13%). Soluble dietary fiber was 0.66 g/L in beverage, and 66% of total extractable polyphenols contained in Roselle flower passed to the beverage and showed an antioxidant capacity of 335 micromoL trolox equivalents/100 mL beverage measured by ABTS. These data suggest that Roselle flower beverage intake in the Mexican diet may contribute around 166 and 165 mg/per serving to the intake of dietary fiber and polyphenols, respectively. The health benefits from consumption of Hibiscus beverage could be of considerable benefit to the whole population.     

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.     

Characterization of the aroma-active compounds in pink guava (Psidium guajava, L.) by application of the aroma extract dilution analysis

The volatiles present in fresh, pink-fleshed Colombian guavas ( Psidium guajava, L.), variety regional rojo, were carefully isolated by solvent extraction followed by solvent-assisted flavor evaporation, and the aroma-active areas in the gas chromatogram were screened by application of the aroma extract dilution analysis. The results of the identification experiments in combination with the FD factors revealed 4-methoxy-2,5-dimethyl-3(2 H)-furanone, 4-hydroxy-2,5-dimethyl-3(2 H)-furanone, 3-sulfanylhexyl acetate, and 3-sulfanyl-1-hexanol followed by 3-hydroxy-4,5-dimethyl-2(5 H)-furanone, ( Z)-3-hexenal, trans-4,5-epoxy-( E)-2-decenal, cinnamyl alcohol, ethyl butanoate, hexanal, methional, and cinnamyl acetate as important aroma contributors. Enantioselective gas chromatography revealed an enantiomeric distribution close to the racemate in 3-sulfanylhexyl acetate as well as in 3-sulfanyl-1-hexanol. In addition, two fruity smelling diastereomeric methyl 2-hydroxy-3-methylpentanoates were identified as the ( R,S)- and the ( S,S)-isomers, whereas the ( S,R)- and ( R,R)-isomers were absent. Seven odorants were identified for the first time in guavas, among them 3-sulfanylhexyl acetate, 3-sulfanyl-1-hexanol, 3-hydroxy-4,5-dimethyl-2(5 H)-furanone, trans-4,5-epoxy-( E)-2-decenal, and methional were the most odor-active.     

Chemometric studies of chemical compounds in five cultivars of potatoes from Tenerife

A statistical study of correlation and multivariate analysis on the chemical composition of five cultivars of potatoes harvested in Tenerife was carried out to establish the relationships between the chemical compounds and, therefore, to differentiate the samples according to traditional and recent importation potatoes, cultivars, and species/subspecies. A large number of significant correlations between the chemical compounds were found, which suggests biochemical relationships among them. After factor analysis, the dimension space was reduced from 24 variables to eight factors, accounting for 77.2% of the total variance. Starch, moisture, organic acids, and metals are the variables that make it possible to characterize the system without losing very much information. Total differentiation of potato samples according to the criteria species/subspecies and cultivars was obtained using discriminant analysis with all the variables. However, with only four variables (weight of tuber, starch, amylose, and glucose + fructose) it is possible to differentiate between the traditional and recent importation potatoes.     

Remobilization efficiency and photosynthetic characteristics of five barley (Hordeum vulgare L.) cultivars under terminal drought stress

Drought is an important limiting factor which can cause major loss in barley productivity. A field experiment was conducted to investigate the effects of irrigation regimes on assimilate remobilization and photosynthetic characteristics of five barley cultivars in 2012 and 2013. There were four levels of irrigation including well-watered [soil moisture content in root depth kept at 100% field capacity (FC)], mild drought (75% FC), severe drought (50% FC), and very severe drought (25% FC). Results showed that Karoon and Valfajr cultivars had the maximum net photosynthetic rate (P_n) ranged from 16.3 to 19.3 µmol CO₂ m^?2 s^?1 under very severe drought. Stomatal conductance (gs) was affected by drought so that Karoon and Valfajr had the lowest gs under severe and very severe drought. By improving the drought, remobilization efficiency in Karoon and Valfajr increased from 18.3% in well-watered to 54.1% under severe drought. In both years under severe and very severe drought, maximum 1000-grain weight and grain yield was obtained in Valfajr and Karoon. Overall, in arid areas, applying suitable irrigation regimes such as mild or severe drought can control soil drying, so that suitable cultivars such as Karoon and Valfajr can rehydrate overnight, and yield might not be inhibited severely.     

Extraction of polyphenols from processed black currant (Ribes nigrum L.) residues

The total phenol and anthocyanin contents of black currant pomace and black currant press residue (BPR) extracts, extracted with formic acid in methanol or with methanol/water/acetic acid, were studied. Anthocyanins and other phenols were identified by means of reversed phase HPLC, and differences between the two plant materials were monitored. In all BPR extracts, phenol levels, determined by the Folin-Ciocalteu method, were 8-9 times higher than in the pomace extracts. Acid hydrolysis liberated a much higher concentration of phenols from the pomace than from the black currant press residue. HPLC analysis revealed that delphinidin-3-O-glucoside, delphinidin-3-O-rutinoside, cyanidin-3-O-glucoside, and cyanidin-3-O-rutinoside were the major anthocyanins and constituted the main phenol class ( approximately 90%) in both types of black currant tissues tested. However, anthocyanins were present in considerably lower amounts in the pomace than in the BPR. In accordance with the total phenol content, the antioxidant activity determined by scavenging of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation, the ABTS(*)(+) assay, showed that BPR extracts prepared by solvent extraction exhibited significantly higher (7-10 times) radical scavenging activity than the pomace extracts, and BPR anthocyanins contributed significantly (74 and 77%) to the observed high radical scavenging capacity of the corresponding extracts.     

Sensory and instrumental evaluation of catnip (Nepeta cataria L.) aroma

The present study investigates the composition of volatile constituents and sensory characteristics of catnip (Nepeta cataria L.) grown in Lithuania. Hydrodistillation, simultaneous distillation-solvent extraction, static headspace, and solid phase microextraction methods were used for the isolation of aroma volatiles. Geranyl acetate, citronellyl acetate, citronellol, and geraniol were the major constituents in catnip. Differences in the quantitative compositions of volatile compounds isolated by the different techniques were considerable. A sensory panel performed sensory analysis of the ground herb, pure essential oil, and extract; aroma profiles of the products were expressed graphically, and some effects of odor qualities of individual compounds present in catnip on the overall aroma of this herb were observed.     

Effect of antioxidant protection of must on volatile compounds and aroma shelf life of Falanghina (Vitis vinifera L.) wine

Two vinification methods involving different degrees of antioxidant protection of Falanghina must during prefermentative steps, and referred as HAMP (high antioxidant must protection) and LAMP (low antioxidant must protection), were compared in terms of fermentation performances of four different yeast strains, composition of the volatile fraction of wines at the end of alcoholic fermentation, and shelf life of wines during storage. The use of HAMP technology resulted in wines with lower volatile acidity and higher concentrations of medium-chain fatty acid ethyl esters, acetates, and volatile fatty acids. For two of the four strains a lower concentration of isoamyl alcohol was also observed. HAMP wines also revealed increased shelf life because of the higher concentration of odor active esters at the end of storage and better preservation of varietal aromas.     

Characterization of volatiles in bullock's heart (Annona reticulata L.) fruit cultivars from Cuba

Volatile compounds were isolated from four cultivars of bullock's heart fruit (Cenizo, Rojo, Verde, and De Ojo) by simultaneous steam distillation-solvent extraction. Compounds were identified by HRGC and capillary GC-MS. One hundred and eighty compounds were identified in the aroma extracts, of which alpha-pinene, beta-pinene, myrcene, limonene, terpinen-4-ol, and germacrene D were found to be the major constituents. Fruit from cv. De Ojo containing the highest concentration of total volatile and the highest major terpenoid content had the highest custard-like and overall fruity aroma intensity. The presence of many terpenic compounds is thought to contribute to the unique flavor of the bullock's heart fruit.     

Variation and correlation analysis of flavonoids and carotenoids in Korean pigmented rice (Oryza sativa L.) cultivars

Flavonoids and carotenoids of pigmented rice ( Oryza sativa L.), including five black cultivars and two red cultivars, from Korea were characterized to determine the diversity among the phytochemicals and to analyze the relationships among their contents. Black cultivars were higher in flavonoids and carotenoids than the red and white cultivars. The profiles of eight phytochemicals identified from the rice grains were subjected to principal component analysis (PCA) to evaluate the differences among cultivars. PCA could fully distinguish between these cultivars. The Heugjinjubyeo (BR-1) and Heugseolbyeo (BR-2) cultivars were separated from the others based on flavonoid and carotenoid concentrations. Flavonoid contents had a positive correlation with carotenoid contents among all rice grains. The BR-1 and BR-2 cultivars appear to be good candidates for future breeding programs because they have simultaneously high flavonoid and carotenoid contents.     

Carotenoid biosynthesis changes in five red pepper (Capsicum annuum L.) cultivars during ripening. Cultivar selection for breeding

Changes in the biosynthesis of individual carotenoid pigments have been investigated during fruit ripening of five cultivars of red pepper (Capsicum annuum L.): Mana, Numex, Belrubi, Delfin, and Negral (a chlorophyll-retaining mutant when ripe). The study was carried out throughout the ripening process, and with special emphasis on the ripe stage, to discover possible differences between cultivars and to characterize these by their carotenoid pattern and content for selecting the best varieties for breeding programs. Ripening fruit of the five cultivars showed the typical and characteristic pattern of carotenoid biosynthesis for the Capsicum genus. In the five cultivars, lutein and neoxanthin, both characteristic chloroplast pigments, decreased in concentration with ripening and eventually disappeared. beta-Carotene, antheraxanthin, and violaxanthin increased in concentration, and other pigments were biosynthesized de novo: zeaxanthin, beta-cryptoxanthin, capsanthin, capsorubin, capsanthin-5,6-epoxide, and cucurbitaxanthin A. A pool of zeaxanthin stands out of the rest of pigment during ripening, which reveals the importance of this pigment as a branching point in the carotenoid biosynthesis in Capsicum. Quantitatively, Negral cultivar showed the highest increase in total carotenoid content (48. 39-fold), followed by Mana and Delfin with 38.03- and 36.8-fold, respectively, and by Belrubi and Numex with 28.03- and 23.48-fold, respectively. In all the red varieties, there was an inverse relationship between total carotenoid content and the red to yellow isochromic pigment fraction ratio (R/Y) and the capsanthin-to-zeaxanthin ratio (Caps/Zeax). This seems to be related to the carotenogenic capacity of the cultivar, and thus selection and breeding should not only seek a higher total carotenoid content but also attempt to increase these ratios. In the present study, the cultivar Mana had the highest total carotenoid content (13 208 mg/kg dwt), but the lowest R/Y (1.25) and Caps/Zeax (3.38) ratios, which are therefore the parameters to improve. The cultivar Negral had a high carotenoid content (8797 mg/kg dwt) and high R/Y and Caps/Zeax ratios and could be used for transfer of these characters in direct crosses with the cultivar Mana. The cultivar Numex had the highest Caps/Zeax ratio (7.17) and is thus an ideal progenitor for this character.     

Efficient and sensitive method for quantitative analysis of alkaloids in hardinggrass (Phalaris aquatica L.)

An efficient high-performance thin-layer chromatography (HPTLC) method for the analysis of alkaloids in hardinggrass (Phalaris aquatica L.) was developed. The method employed HPTLC glass plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of ethyl acetate/chloroform/7 N NH4OH in methanol (8:2:1, v/v/v). Using unidimensional double-development, bands were well separated for 10 alkaloid standards as well as alkaloids observed in hardinggrass plant extracts. Identities of compounds observed using HPTLC were validated by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Software was used to quantify individual alkaloids in plant samples based on HPTLC retention factors and intensities relative to standards of known concentration. Correlation coefficients of 0.99 were obtained between estimated and actual concentrations for four standards (methyltyramine, hordenine, gramine, and 5-methoxydimethyltryptamine), with linearity in the range of 120-3840 ng/spot. The HPTLC method is repeatable and specific for beta-carboline, tryptamine, gramine, and tyramine type alkaloids in mixed standard and plant extracts. Initial results indicate substantial variation in alkaloid composition among and within hardinggrass populations.     

Assessing genetic diversity of sweet potato (Ipomoea batatas (L.) Lam.) cultivars from tropical America using AFLP

The sweet potato genebank at the International Potato Center (CIP) maintains 5,526 cultivated I. batatas accessions from 57 countries. Knowledge of the genetic structure in this collection is essential for rational germplasm conservation and utilization. Sixty-nine sweet potato cultivars from 4 geographical regions (including 13 countries) of Latin America were randomly sampled and fingerprinted using AFLP markers. A total of 210 polymorphic and clearly scorable fragments were generated. A geographic pattern of diversity distribution was revealed by mean similarity, multidimensional scaling (MDS), and analysis of molecular variance (AMOVA). The highest genetic diversity was found in Central America, whereas the lowest was in Peru-Ecuador. The within-region variation was the major source of molecular variance. The between-regions variation, although it only explains 10.0% of the total diversity, is statistically significant. Cultivars from Peru-Ecuador, with the lowest level of within region diversity, made the most significant contribution to the between region differentiation. These results support the hypothesis that Central America is the primary center of diversity and most likely the center of origin of sweet potato. Peru-Ecuador should be considered as a secondary center of sweet potato diversity.     

Approaches to wine aroma: release of aroma compounds from reactions between cysteine and carbonyl compounds in wine

Under conditions close to those of wine, that is, low pH, aqueous medium, and low temperatures, this work examines the role of carbonyl (acetoin and acetol) and dicarbonyl (glyoxal, methylglyoxal, diacetyl, and pentane-2,3-dione) compounds associated with cysteine in the formation of odorous products. In particular, thiazole, 4-methylthiazole, 2-acetylthiazole, and trimethyloxazole and two sulfur and oxygenated heterocyclic compounds, 2-furanmethanethiol and thiophene-2-thiol, are examined. For thiophene-2-thiol, the reactional mechanism is proposed. Attempts were made to detect these compounds in wines from various origins. Certain molecules were identified for the first time in wine.     

Characterization of odorants causing an atypical aroma in white pepper powder (Piper nigrum L.) based on quantitative measurements and orthonasal breakthrough thresholds

Application of the aroma extract dilution analysis on an extract of white pepper powder showing an intense fecal, cowshed-like off-flavor revealed 3-methylindole (fecal, swine-manure) and 4-methylphenol (fecal, horse-like) with the highest flavor dilution (FD) factors among the 22 odor-active compounds detected. In addition, high FD factors and/or undesirable odor qualities suggested 3-methylphenol (phenolic), butanoic acid (cheese-like), and 2- and 3-methylbutanoic acid (cheese-like) as well as pentanoic acid and hexanoic acid (cheese-like odors) as contributors to the malodor. Although the intensities of the off-note were clearly different in 50 commercial samples of white pepper, quantitation of 3-methylindole and 3- and 4-methylphenol as well as of the five short-chain acids by means of stable isotope dilution assays showed similar concentrations in most of the samples. Storage of a freshly ground white pepper powder for up to 7 months revealed a significant decrease in the typical odor qualities of white pepper and an increase in the fecal odor note with storage time. Because the concentrations of the odorants mentioned above were not much changed during storage, possibly very volatile odorants, such as alpha-pinene, which are able to mask the malodor, are lost during storage of, in particular, pepper powders. On the basis of odor activity values, which were calculated using breakthrough thresholds, in particular, 3-methylindole, 4-methylphenol, 3-methylphenol, and butanoic acid could be suggested as the main sources of the fecal off-flavor.