Fate of resveratrol and piceid through different hop processings and storage times

Trans-Piceid and trans-resveratrol contents of hop cones, hop pellets, CO2 extracts, and spent hop from American varieties (harvest 2004) were determined by reverse-phase high-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry [RP-HPLC-APCI(+)-MS/MS]. Pelletization induced strong stilbene degradation in some cultivars. Similarly, 1 year of storage at 4 degrees C led to a huge loss of trans-piceid, especially in the case of hop cones (much faster than in model media, although well protected from light and oxygen). Therefore, after 8 months of storage, the overall stilbene content was in the same range whatever the conditioned form. Absent in fresh hop cones or pellets, cis-resveratrol was released from cis-piceid in all stored samples. On the other hand, no delta-viniferin was detected despite it is present in light-protected model media spiked with trans-piceid. Because supercritical carbon dioxide proved inefficient for recovering resveratrol and piceid from pellets, spent hop emerged as the most interesting material for subsequent specific stilbene extraction.     

Determination of stilbenes in hop pellets from different cultivars

About 30% of the polyphenols in wort and beer derive from hop, but little is yet known about their nutritional impact. The recent discovery of trans-resveratrol and piceid isomers in hop opens new doors to understanding beer health benefits. In the present work, resveratrol was quantified by HPLC-APCI-MS/MS in pellets from 9 different cultivars. Concentrations ranging from 4 to 9 mg/kg trans-piceid, from 2 to 6 mg/kg cis-piceid, and up to 1 mg/kg trans-resveratrol were detected. As previously shown for total polyphenols and flavonoids, the lower the alpha-acid content, the higher the total stilbene content.     

Identification and genetic structure of wild Italian <Emphasis Type="Italic">Humulus lupulus</Emphasis> L. and comparison with European and American hop cultivars using nuclear microsatellite markers

Nine genic SSR loci were used to evaluate the genetic diversity and identify accessions in wild Italian Humulus lupulus L., in comparison with widely cultivated European and U.S. commercial cultivars. A collection of 80 wild hop samples from Italy and 43 hop cultivars from Europe and U.S., were characterized. Allelic frequency analysis revealed 65 distinct Italian genotypes and differentiated all the commercial cultivars; moreover, specific alleles were observed for wild and cultivated hops. The number of alleles identified in the wild population were 104 and 123 within all the accessions. The maximum polymorphic information content was evidenced for locus HlGA23 in the Italian wild population and in the whole set of accessions (0.905 and 0.902 respectively). The dendrogram constructed from Euclidean distance with the UPGMA method showed two main clusters, one including commercial American and European accessions and one mostly composed by wild Italian accessions. Model-based clustering (Bayesian method) placed the accessions into five germplasm groups, one of which was characterized by Italian genotypes only. The study showed for the first time the great biodiversity present in Italy, and the remarkable differences with European and American hops. It was also found that within the population of north-central Italy a large genetic variability is present, suited to be studied and exploited; this genetic wealth could be used in future breeding programs in order to develop new hop varieties carrying characteristics useful for brewers.     

Comparison of the calystegine composition and content of potato sprouts and tubers from Solanum tuberosum Group Phureja and Solanum tuberosum Group Tuberosum

The calystegines detected in tubers from 17 Phureja ( S. tuberosum Group Phureja) lines and five Tuberosum ( S. tuberosum Group Tuberosum) cultivars were identified as the A 3 and B 2 structural types. Their concentration in whole tubers was of a similar order of magnitude in both species, as was the variability in the ratio of B 2 to A 3. On average, calystegine concentrations in the peel were about 13 times that found in the flesh for the five Tuberosum cultivars, and 4 times higher for four Phureja lines. Removal of the peel reduced the calystegine content by an average of over 50% in Tuberosum but by only 30% in Phureja, despite the latter having the greater proportion of peel. The calystegine content of sprouts was also determined for five Tuberosum cultivars and four Phureja lines and was found to include small amounts of four additional types, B 3, B 4, N 1, and X 2, in addition to the more abundant A 3 and B 2. Concentrations in the sprouts of Tuberosum were on average 100 times higher than that in the tuber flesh and 8 times higher than in the peel, whereas for Phureja, the equivalent values were 30 and 7 times higher, respectively. No correlation was found between sprout concentration and either flesh or peel calystegine concentration.     

The effect of sulfur fertilizer on glucoraphanin levels in broccoli (B. oleracea L. var. italica) at different growth stages

Three sulfur (S) treatements were imposed by applying gypsum to three broccoli cultivars (Claudia, Marathon, and TB-234) known to differ in glucoraphanin content of mature seeds. The S treatments were control (very low added S), low S (23 kg S ha(-)(1)), and high S (92 kg S ha(-)(1)). The gypsum applications during the early vegetative phase of the three broccoli cultivars increased S uptake and the glucoraphanin content in each plant organ. There were significant genotypic differences for the content of both S and glucoraphanin in all plant organs at different growth stages with gypsum applications. A large increase in S and glucoraphanin content was found in the green heads of broccoli and mature seeds. S present in glucoraphanin accounted for only 4-10% of total S content in broccoli heads. However, S present in glucoraphanin in mature seeds accounted for 40-46% of the total S in the seeds of moderate and high glucoraphanin cultivars (Marathon and TB-234). The partitioning of S into glucoraphanin also increased with gypsum applications. Differences in S uptake, S distribution between organs, and partitioning of S into glucoraphanin largely explained the differences in glucoraphanin content in the green heads and mature seeds for the three broccoli cultivars and three S treatments.     

Developmental and varietal differences in volatile ester formation and acetyl-CoA: alcohol acetyl transferase activities in apple (Malus domestica Borkh.) fruit

Apple (Malus domestica Borkh.) cultivars differ in their aroma and composition of volatile acetates in their fruit flesh and peel. Cv. Fuji flesh contains substantial levels of 2-methyl butyl acetate (fruity banana-like odor), while the flesh of cv. Granny Smith apples lacks this compound. Granny Smith apples accumulate mainly hexyl acetate (apple-pear odor) in their peel. Feeding experiments indicated that Fuji apples were able to convert hexanol and 2-methyl butanol to their respective acetate derivatives in vivo, while Granny Smith apples could only convert exogenous hexanol to hexyl acetate. Differential substrate specificities of the in vitro acetyl-CoA:alcohol acetyl transferase (AAT) activities were also detected among cultivars. In Granny Smith apples, the AAT activity was detected only in the peel, and its specificity was almost exclusively restricted to hexanol and cis-3-hexenol. In Fuji apples, the AAT activity was detected in both peel and flesh and apparently accepted a broader range of alcohols as substrates than the Granny Smith enzyme activity. Our data strongly suggest that different AAT activities are operational in apple tissues and cultivars and that these differences contribute to the variation observed in the accumulation of volatile acetates.     

The influence of European and American wild germplasm in hop (<Emphasis Type="Italic">Humulus lupulus</Emphasis> L.) cultivars

Microsatellite variation at the nuclear and chloroplast genomes was evaluated for wild European and wild American hops, in order to assess the genetic diversity and origin of cultivated hops. Seven nuclear loci and 32 chloroplast loci were used in the analysis of 182 hop accessions including wild European (68), wild American (48), and cultivars (66). A total of 116 alleles were identified using 7 nuclear microsatellites showing different averages of polymorphism and distribution in the wild American and European accessions and cultivars. Two main groups were established as revealed by several statistical analyses; one including European wild accessions and cultivars and a second group consisting of American wild accessions. Three polymorphic chloroplast microsatellite loci were detected, six alleles were scored which defined a total of five haplotypes that were exclusive or presented different distribution between American and European wild accessions. A major influence of the wild European haplotypes was detected among hop cultivars. To the best of our knowledge, this is the first work reporting the use of chloroplast microsatellites in hops.     

Zinc Deficiency in Selected Cultivars of Wheat and Barley as Tested in Solution Culture

Abstract

The relative zinc (Zn) efficiencies of 33 wheat and 3 barley cultivars were determined by growing them in chelate‐buffered culture solutions. Zn efficiency, determined by growth in a Zn‐deficient solution relative to that in a medium containing an adequate concentration of Zn, was found to vary between 10% and 63% among the cultivars tested. Out of the 36 cultivars tested, 12 proved to be Zn efficient, 10 were Zn inefficient, and the remaining 14 varieties were classed as intermediate. The most Zn‐efficient cultivars included Bakhtawar, Gatcher S61, Wilgoyne, and Madrigal, and the most Zn inefficient included Durati, Songlen, Excalibur, and Chakwal‐86. Zn‐efficient cultivars accumulated greater amounts of Zn in their shoots than inefficient cultivars, but the correlation between shoot Zn and shoot dry matter production was poor. All the cultivars accumulated higher concentrations of iron (Fe), copper (Cu), manganese (Mn), and phosphorus (P) at deficient levels of Zn, compared with adequate Zn concentrations. The Zn‐inefficient cultivars accumulated higher concentrations of these other elements compared to efficient cultivars.     

Induced Postharvest Yellowing in Southern U.S. Rice Cultivars

Rice can yellow during storage if moisture levels and temperatures are allowed to increase. This postharvest yellowed (PHY), or stackburn, rice is reduced in value but no study has investigated the inherent potential within rice germplasm for limiting PHY. To screen a large number of cultivars for propensity to PHY, a laboratory method for PHY using a small amount of rice was used. Ninety‐eight popular southern U.S. rice cultivars were yellowed under laboratory conditions. Additional samples of the low‐yellowing and high‐yellowing cultivars were retested after two and three years of storage as rough rice using higher amounts and larger containers. All cultivars showed greater color change with the higher amounts of rice and when yellowed as milled rather than as rough rice. Length of time of storage and storage temperature did not affect the degree of PHY. The low‐ and high‐yellowing groups remained distinguishable but the overall high level of coloring in southern U.S. rice cultivars indicates that a more diverse germplasm should be investigated to increase the likelihood of identifying low‐PHY cultivars.     

Metabolism of fenitrothion and conjugation of 3-methyl-4-nitrophenol in tomato plant (Lycopersicon esculentum)

The metabolism of (14)C-labeled fenitrothion (Sumithion, [O,O-dimethyl-O-(3-methyl-4-nitrophenyl)phosphorothioate]) in tomato plant (Lycopersicon esculentum Mill., cv. Ponderosa) grown in the greenhouse equipped with quartz glass was conducted to investigate the effect of sunlight on the behavior of fenitrothion and to elucidate the detailed structure of conjugated metabolites. Tomato plants (BBCH 85) were topically treated with (14)C-labeled fenitrothion twice with a 2 week interval between applications. At 15 days after the second application, more than half of the recovered (14)C was detected as unaltered fenitrothion, glucose, and cellobiose esters of 3-methyl-4-nitrophenol (NMC) in extracts from tomato fruit. The photoinduced formation of the S-methyl isomer of fenitrothion via thiono-thiolo rearrangement was detected only in the surface rinse but at trace amounts. In the whole tomato fruit, fenitrothion, the S isomer, NMC-beta-glucoside, and NMC cellobioside were detected at 34.16, 1.28, 7.47, and 15.07% of the recovered (14)C, respectively. Trace amounts of the oxon analogue of fenitrothion were detected only on tomato leaves. The chemical structure of the cellobiose conjugate of NMC, 1-O-beta-d-glucopyranosyl-(1-->4)-beta-d-glucopyranosyl-3-methyl-4-nitrophenol, was determined by spectroscopic analyses (liquid chromatography-mass spectrometry, NMR), using the metabolite obtained from leaves and stems of tomato plant hydroponically grown with (14)C-labeled NMC.     

Occurrence of Odorant Polyfunctional Thiols in Beers Hopped with Different Cultivars. First Evidence of an S-Cysteine Conjugate in Hop ( Humulus lupulus L.)

Forty-one thiols, mainly β-sulfanylalkyl acetates, β-sulfanylalkyl alcohols, and β-sulfanylalkyl carbonyls, were recently evidenced in hop. In a beer hopped with the Tomahawk cultivar, most of them were found at higher levels than expected. The aim of the present work was to investigate the polyfunctional thiols in beers hopped with different varieties. A few thiols proved not to come only from hop (mainly 2-sulfanylethyl acetate, μg/L levels, and 1-sulfanylpentan-3-one and 1-sulfanylpentan-3-ol, ng/L levels, internal standard (IST) equivalents). The thiol profile of Saaz-hopped beer proved similar to that of the reference beer produced without hop. A high level of 3-sulfanyloctan-1-ol emerged as an indicator of the use of Tomahawk hop (140 ng/L, IST equivalents; FD (flavor dilution) = 65536). In both Cascade- and Tomahawk-hopped beers, 3-sulfanylhexan-1-ol and 3-sulfanylheptan-1-ol were smelled at high flavor dilutions, although only for the latter, significant amounts of the unreduced 3-sulfanylheptanal were found in hop. As already claimed for hop authentication, 3-sulfanyl-4-methylpentan-1-ol remains a good marker of Nelson Sauvin-hopped beers (548 ng/L, IST equivalents; FD = 65536), together with 4-sulfanyl-4-methylpentan-2-one (128 ng/L, FD = 4096). As illustrated by the huge production occurring during fermentation, accurate prediction of hop varietal impact requires quantitating thiol adducts in hop. S-3-(1-Hydroxyhexyl)cysteine was evidenced here for the first time in Cascade hop.     

Categorizing Rice Cultivars Based on Cluster Analysis of Amylose Content,Protein Content and Sensory Attributes

Presently, rice cultivars are categorized according to grain dimensions, amylose content, and alkali spreading value (gelatinization temperature type). Categorization of rice cultivars based on total sensory impact is needed. This work endeavors to divide world rices into groups based on amylose, protein, flavor, and texture properties. Ninety‐one rice samples representing 79 different cultivars and seven growing locations were separated into seven groups with Ward's Cluster Analysis. Cluster 1 included a third of the rice samples and had cultivars with a large diversity of grain shapes and amylose contents. Mean attribute scores for this cluster were near the grand mean for the collective rice samples for nearly every sensory attribute. Cluster 2 included conventional U.S. short‐ and medium‐grain cultivars. Cluster 3 included conventional U.S. medium cultivars that were produced in Louisiana. Mean sensory scores for this cluster characterized these cultivars as having relatively undesirable flavor and texture attributes. Cluster 4 included Japanese premium quality cultivars and U.S. medium‐grain cultivars developed for the Japanese market. Cluster 5 included high‐amylose, indica types that had relatively firm textural properties. Cluster 6 included relatively soft cooking, aromatic cultivars. Cluster 7 included waxy cultivars and other soft cooking grains. In several cases, the production environment (location, weather effects, etc.) influenced flavor and texture characteristics and resulted in the cultivar falling into an unexpected cluster. This categorization serves as a catalyst for indexing rice cultivars for cooking and processing qualities.     

YIELD AND MINERAL CONCENTRATIONS OF SOUTHEASTERN UNITED STATES OAT CULTIVARS USED FOR FORAGE

A shift in oat (Avena sativa L.) production from grain to forage (hay and grazing) is occurring in the southeastern USA. However, most available cultivars were developed for improved grain production, rather than forage yield. We field tested several standard and new oat releases over 2 years, using repeated clippings to determine forage yield, nutrient uptake, and the potential to match plant nutrients with cattle mineral dietary needs. There were no differences in total annual forage yield among the tested cultivars within years but there was a difference between years. Forage tissue phosphorus (P), magnesium (Mg), and calcium (Ca) were sufficient, potassium (K), sulfur (S), and manganese (Mn) were excessive, and iron (Fe), copper (Cu), and zinc (Zn) were occasionally or frequently deficient to meet daily cattle dietary mineral needs. Sulfur, Cu, Fe, Zn, and Mn may be the most challenging to regulate in U.S. Coastal Plain soils at concentrations that satisfy both, oat and cattle nutritional requirements.     

Comparison of fatty acid and polar lipid contents of tubers from two potato species, Solanum tuberosum and Solanum phureja

Total and individual fatty acid contents were determined in raw tubers of four genotypes from each of the two species Solanum phureja and S. tuberosum. The four S. phureja genotypes contained statistically significantly higher concentrations of total fatty acids, with their average value being 37% greater than that for the mean of the four S. tuberosum cultivars. In both species, a total of 17 fatty acids were detected in quantifiable amounts, and in all genotypes the predominant fatty acid was linoleic followed by alpha-linolenic and palmitic acids. Unusually, 15-methyl hexadecanoate was present as a minor acid in both species. Although a number of statistically significant differences in the fatty acid percentage compositions were found between and within the two species, these were generally small. Averaged over all species and genotypes, tuber storage resulted in an initial small but statistically significant increase in total fatty acid content, but prolonged storage resulted in a fall to the initial values detected close to harvest. The same trend was evident for S. phureja alone (for mean values of all genotypes), but for S. tuberosum the total fatty acid content remained constant over the whole storage period. For both species, the contents (both as absolute levels and as percent compositions) of linoleic acid decreased and alpha-linolenic acid increased in tubers over the whole storage period, and possible mechanisms are discussed. Also, the absolute levels of these two acids were greater in S. phureja than in S. tuberosum, and this is discussed in relation to the development of flavor-related compounds during cooking. The polar lipids of one representative of S. tuberosum and of S. phureja were qualitatively similar. There were only minor differences in the polar lipid percentage compositions and in the corresponding fatty acid compositions of the individual polar lipids between the two species, although the absolute levels of the total, and of some individual, polar lipids were higher in S. phureja.     

Hop as an interesting source of resveratrol for brewers: optimization of the extraction and quantitative study by liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry

Nowadays, hop is used almost exclusively by brewers for bitterness and flavor. Although hop polyphenols have been widely studied in the past decade for their antioxidant activity in the boiling kettle, very little is known about their real impact on health. The discovery of resveratrol in hop pellets highlights the potential health-promoting effect of moderate beer consumption. Here, we have optimized a quantitative extraction procedure for resveratrol in hop pellets. Preliminary removal of hydrophobic bitter compounds with toluene and cyclohexane at room temperature allows 99% trans-resveratrol recovery by ethanol:water (75:25, v/v) solid/liquid extraction at 60 degrees C. Reverse phase liquid chromatography proves an excellent means of separating isomers. In addition, we have compared two mass spectrometry ionization methods-atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI)-in both the positive and the negative modes. On the basis of standard additions applied with the optimized extraction procedure and reverse phase high-performance liquid chromatography-APCI(+)-tandem mass spectrometry, it appears that Tomahawk hop pellets (T90, harvest 2002) contain 0.5 ppm trans-resveratrol, 2 ppm trans-piceid, no cis-resveratrol, and 0.9 ppm cis-piceid.     

Use of GC-olfactometry to identify the hop aromatic compounds in beer

This paper describes a sensorial aroma extract dilution analysis (AEDA) approach to the analysis of beer aromas derived from hops. To obtain an extract with an odor representative of the original product, the XAD extraction procedure was applied and the experimental conditions were optimized. The aromagrams of three beers were compared: one brewed without hops, one brewed with Saaz hop pellets, and one brewed with Challenger hop pellets. One spicy/hoppy compound, unmodified from hop to beer, proved responsible for the most intense odor in both hopped beer extracts. Another flavoring compound in hops, linalool, also survives through the process to the final beer. Other compounds such as gamma-nonalactone and humuladienone, although not found in our extracts of hop, significantly modify beer aromagrams after hopping. Sulfur compounds characteristic of Challenger hops proved to be at least partially responsible for the unpleasant flavor found in the corresponding beer.     

Effects of Nitrogen and Sulfur Fertilizers on Gliadin Composition of Several Cultivars of Durum Wheat

Four fertilizer treatments were applied to 10 cultivars of durum wheat (Triticum turgidum var. durum L.) in three seasons of designed field trials. The fertilizer treatments were N0S0 ‐ neither N nor S applied; N1S0 ‐ only N applied; N1S1 ‐ both N and S applied; N0S1 ‐ only S applied. It was found, through densitometric SDS‐PAGE, that the relative proportion of different gliadin components was influenced by the distinct regimes, even though our region in the center of the Argentinean Pampa is not considered to be deficient in soil S‐availability. The effects observed were more marked in one particular season of the three studied, were principally associated with the treatment expected to produce the maximum degree of grain S‐deficiency (N1S0), and were consistent with the hypothesis that the relative content of S‐poor gliadins increases under conditions of S‐deficiency, as has been found in related crops. Multivariate reverse‐phase high‐performance liquid chromatography (RP‐HPLC) analysis of samples from the season most affected generally supported these observations, but refined them in identifying quantitative differences between all four fertilizer treatments for the cultivars studied. These findings imply that differences in industrial quality might also be expected between the fertilizer treatments. RP‐HPLC also identified numerous genetically controlled qualitative differences in the gliadins between the cultivars studied, adding to previous published work on these cultivars based on SDS‐PAGE. These observations confirmed that one particular cultivar of very low gluten strength showed a gliadin profile markedly distinct from the remaining cultivars studied.     

Changes of folate and other potential health-promoting phytochemicals in legume seeds as affected by germination

Folate deficiency associated with low dietary intake is a well-documented public health problem, resulting in serious health and socioeconomic burdens. Therefore, optimization of the germination process of different cultivars of legume seeds in relation to the content and composition of folate, vitamin C, and total phenolics and total antioxidant capacity was carried out to maximize the health-promoting properties. The content and composition of folate, vitamin C, and total phenolic and total antioxidant capacities varied between species, among cultivars, and with germination time. During germination, total folate content was maximum at 815.2 μg/100 g fresh weight in soybean sprout and at 675.4 μg/100 g fresh weight in mungbean sprout on the fourth day, which were equivalent to, respectively, 3.5- and 3.9-fold increases in the seed's content, and total folate content strongly decreased thereafter. 5-CH(3)-H(4)folate was the most abundant folate species in legume sprouts and reached a maximum on the fourth day. Vitamin C was not detected in raw seeds, and its content increased sharply in soybean and mungbean sprouts and reached a maximum at the fourth day of germination (29 and 27.7 mg/100 g fresh weight, respectively). Germination of soybean and mungbean for 4 days provided the largest amount of total folate as well as the more stable species 5-CH(3)-H(4)folate and also brought about large amounts of vitamin C and total phenolics and substantial antioxidant capacities.     

Inventory methods for finding historically cultivated hop (<Emphasis Type="Italic">Humulus lupulus</Emphasis> L.) in Sweden

The relationship between the conservation of plant genetic resources and their culture history is intimate. Consequently, biodiversity research must also take into account historical and cultural factors. An inventory of plants collected from all over Sweden was made with the aim of establishing a national Swedish gene bank for once cultivated hop. Only female hop, which could be regarded as cultivated hop on the basis of history, were selected. In this study, two different inventory methods were used: one based on plant habitat and the other involving the use of historical documents, primarily large-scale maps from the first half of the seventeenth century, used to locate their cultivars today. The documented history of the hop, combined with its biology, is the basis for the methods used. Hop is the only Swedish crop that according to a 1442 law had to be cultivated. The law lasted for over 400 years. Since the hop is a perennial, dioecious plant and only female individuals are cultivated, over time very few genetic recombination events are expected. Today, it is possible to connect and identify living plants using historical documents. The degree of connection between today’s living plants and the historical evidence for hop cultivation differ between the two methods.