Comparative study of carbohydrates in the two major species of jute (Corchorus capsularis and Corchorus olitorius

Unretted and retted bark and stem of Corchorus olitorius L and retted stem of C capsularis L, two species of jute, were analysed for ash, lignin, low molecular weight carbohydrates and polysaccharides. The results are compared with those from C capsularis published earlier. The unretted bark and stem of C olitorius contained less low molecular weight carbohydrates than the corresponding fractions of C capsularis. C olitorius bark contained less cellulose and more hemicellulose than C capsularis, particularly after retting. Xylans isolated from the retted fibre and stem of C olitorius were found to have a similar composition to those from C capsularis.     

Phenolic acids in the jute plant (corchorus capsularis)

The bark and the stem of unretted jute plant (Corchorus capsularis) were found to contain various free, glycosidic and ester-linked phenolic acids. From an 80% aqueous ethanol extract, p-coumaric, ferulic, caffeic, vanillic and p-hydroxybenzoic acids were identified and quantified. p-Coumaric acid, the major component, and β-sitosterol were isolated and characterised.     

Analysis of carbohydrates in the jute plant (Corchorus capsularis)

Jute plants (Corchorus capsularis) were fractionated into bark and stick. Jute fibre was produced from the bark by retting in water. Polysaccharides and lignin (estimated as Klason lignin) were the major constituents of the three jute fractions. Glucose, fructose, sucrose, six low-molecular weight sugar alcohols (glycerol, erythritol, threitol, rhamnitol, arabinitol, and mannitol), and two inositols (myo-inositol and scyllitol) were identified and quantified in the bark; all these compounds, except rhamnitol were also measured in the stick. Cellulose, xylans and pectins were major polysaccharide constituents in the three jute fractions. During fibre production by retting, extractives and pectic polysaccharides were solubilised or degraded, producing a fibre material enriched in cellulose and xylans.     

Carbohydrate composition and content of organic acids in fresh and stored apples

The contents of low‐molecular‐weight carbohydrates (LMWC; sorbitol, glucose, fructose and sucrose), starch, dietary fibre and organic acids were determined in seven apple cultivars at the start and end of the consumption interval. The cultivars included were Summered, Aroma, Ingrid Marie, Cox Orange, Mutzu, Belle de Boskoop and Jonagold. The total content of LMWC ranged between 615 and 716 g kg⁻¹ dry matter (DM). The dominating sugar was fructose, corresponding to on average 57% (range 48–62%) of the total LMWC. However, in Cox Orange the sucrose content was considerably higher and the fructose and sucrose contents constituted approximately 46% each. Total dietary fibre content was similar in the cultivars (total dietary fibre 160 ± 20 g kg⁻¹ DM), except for Belle de Boskoop which had a higher content (203 g kg⁻¹ DM). Mutzu had a lower proportion of soluble fibre (27% of total dietary fibre) compared with the others (mean 32%). The organic acid content was on average 80 ± 4 g kg⁻¹ DM, except for two of the cultivars (Summered and Belle de Boskoop) which had a higher content (105 ± 6 g kg⁻¹ DM). Interestingly, the organic acid content was only slightly reduced upon storage in the case of Belle de Boskoop, whereas there was a substantial decrease in all the other cultivars (p < 0.001). Sucrose (p < 0.01) and starch (p < 0.05) contents decreased in all cultivars following storage, whereas sorbitol (p < 0.05) and total dietary fibre (p < 0.05) contents increased. It is concluded that the observed differences in composition are of such magnitude that they may affect both nutritional and sensory properties. © 2000 Society of Chemical Industry     

苹果酒中酚酸、黄烷-3-醇的检测

以小国光(Ralls)和富士(Fuji)及其所酿制的新鲜苹果酒为试验材料,采用反相高效液相色谱法测定分析苹果原汁、发酵中酒样和苹果成品酒中11种酚酸、5种黄烷-3-醇的含量。结果表明:苹果和苹果酒中存在4种酚酸(原儿茶酸、绿原酸、咖啡酸、对-香豆酸)、2种黄烷-3-醇(儿茶素和表儿茶素);不同品种的苹果原汁和苹果成品酒中酚类物质的含量都存在显著差异。其中,小国光苹果和小国光苹果酒中的酚类物质总含量较高;对于每个品种,绿原酸都是最主要的酚酸类物质,含量最高的黄烷-3-醇类物质都是表儿茶素。随着发酵过程的进行,苹果酒中酚类物质的含量有不同程度的增加。其增加趋势为S型曲线,即先平缓再较快再平缓。     

Lignification of switchgrass (Panicum virgatum) and big bluestem (Andropogon gerardii) plant parts during maturation and its effect on fibre degradability

Five cultivars of switchgrass (Panicum virgatum L) and four cultivars of big bluestem (Andropogon gerardii Vitman) were harvested at vegetative, boot and heading stages of maturity. Leaf and stem fractions were analysed for detergent fibre composition and 48-h ruminal in-vitro degradability, ester- and ether-linked non-core lignin phenolic acids, and core lignin composition. Big bluestem leaves contained more neutral detergent fibre than switchgrass, but general composition of the fibre did not differ. Stem fibre of switchgrass had relatively lower levels of cellulose and lignin at the vegetative stage than observed in big bluestem. Esterified and etherified p-coumaric and ferulic acid concentrations were generally higher in switchgrass plant parts. Yield of nitrobenzene oxidation products from core lignin was greater for switchgrass leaves, but very little difference in composition was noted. Leaf tissue contained lower concentrations of all lignin components than stems. Maturation resulted in increased total lignification, but all components did not respond in the same manner. Variation for all measures of lignification seemed to be as great within species as between the grass species. Degradability of fibre declined with maturation. The only species difference was that switchgrass fibre was more degradable at the vegetative stage. Relationships between lignification and fibre degradability were in agreement with some, but not all, previously reported relationships. Concentration of core lignin was only a significant predictor of fibre degradability when the relationship was examined across maturity stages. Within a stage of maturity, lignin composition was more closely related to fibre degradability than was concentration. However, the best predictors of fibre digestibility differed among species, plant part and maturity.     

苦荞中酚酸和原花色素的分析测定

采用了反相液相色谱法 (RP HPLC) ,结合二极管阵列检测器 (DAD)分析 ,测定了苦荞籽粒各部分 (壳、麸皮、外层粉、内层粉 )的酚酸和原花色素。测定结果表明 ,苦荞中的酚酸种类主要是苯甲酸类———原儿茶酸和对羟基苯甲酸 ;酚酸总量在 94.61～ 1745 .3 3mg/kg。原花色素含量在 0 .0 3 %～ 5 .0 3 %。     

Distribution of bound and free phenolic acids in oranges (Citrus sinensis) and Grapefruits (Citrus paradisi)

Free phenolic acids may be the precursors for vinyl phenols and off-flavours formed in citrus products during storage. Quantitative determination of free and bound phenolic acids in fruit parts of grapefruit (Citrus paradisi Macfadyen) and oranges (Citrus sinensis (L) Osbeck) was performed by extraction with ethyl acetate, silica gel column chromatography and HPLC analyses of samples before and after alkaline hydrolysis. The content of free and bound phenolic acids was further determined in juice derived from fruit harvested early, mid and late in season. As found previously for ferulic acid, phenolic acids occur mainly in bound forms in grapefruits and oranges. In both fruits the peels contained the major portion of cinnamic acids compared with the endocarp, and the flavedo was richer in hydroxycinnamic acids than the albedo. In most cases, hydroxycinnamic acid content was in the following order: ferulic acid>sinapic acid>coumaric acid>caffeic acid. Results showed that the content of bound cinnamic acids was unchanged or slightly elevated from early to late season. However, the content of free acids was reduced during that period.     

Phenolic composition and antioxidant activity of white mulberry (Morus alba L.) fruits

Eight major mulberry cultivars [Nakhonratchasima 60 (NS 60), Buriram 60 (BR 60), Chumphon (CP), Wavee (WV), Chaingmai (CM), Pikultong (PT), Kamphaengsaen (KS) and Kamnanchul (KJ)] cultivated in Thailand were assessed for their flavonoid and phenolic acid composition using HPLC and tested for antioxidant potential using 2,2‐diphenyl‐1‐picrylhydrazyl hydrate (DPPH) assay. The total phenolic content (TPC) ranged from 104.78 to 213.53 mg GAE/100 g DW, and total flavonoid content (TFC) ranged from 69.58 to 211.01 mg CE/100 g DW. The major flavonoid compounds in mulberry fruit cultivars were (+)‐catechin (309.26–750.01 mg/100 g DW), procyanidin B1 (62.59–224.41 mg/100 g DW), quercetin (5.36–58.42 mg/100 g DW), rutin (18.73–26.90 mg/100 g DW) and (?)‐epicatechin (8.47–29.21 mg/100 g DW). Gallic acid, cinnamic acid and p‐hydroxybenzoic acid were found to be the major phenolic acids in mulberry fruit cultivars. The gallic acid and cinnamic acid contents ranged from 7.33 to 23.90 mg/100 g DW and from 11.64 to 15.05 mg/100 g DW, respectively. p‐Hydroxybenzoic acid content ranged from 1.77 mg/100 g DW (PT) to 7.13 mg/100 g DW (KJ). DPPH‐scavenging ability was excellent for ethanolic extract of NS 60, and EC₅₀ value of NS 60 (241.83 μg mL^?1) was significantly lower than those of the others (P < 0.05). TPC and TFC of the mulberry fruit were positively correlated with the DPPH‐scavenging ability.     

Biodegradability of Free Monomeric and Cell-Wall-Bound Phenolic Acids in Maize Stover by Two Strains of White-Rot Fungi

Development of fungal bioconversion technology to upgrade feeding value of fibrous crop residues into animal feed requires the understanding of the impact of fungal treatments on cell wall phenolic acids. This study investigated the capacity of two strains of white-rot fungi, Phanerochaete chrysosporium and Phlebia brevispora , in degrading cell wall-bound phenolic acids in maize ( Zea maize L) stover and the free phenolic monomers in a liquid culture medium. In the study, 150 mg litre⁻¹ of p -coumaric acid (PCA), ferulic acid (FA), syringic acid (SYA), p -hydroxybenzoic acid (PHBA), vanillic acid (VA), and 200 mg litre⁻¹ of caffeic acid (CA) were added to a liquid nutrient medium and incubated with each of the fungi for 28 days. The results indicated that within 21 days the fungal treatments completely removed the added PCA and FA from the medium, and over 94% of SYA was degraded after 28 days. During the incubation periods, VA and PHBA were also extensively removed by P chrysosporium , but resistant to degradation by P brevispora . Disappearance of caffeic acid from the medium was related to both fungal degradation and abiotic hydrolysis. In the culture media, P chrysosporium was superior to P brevispora in removing the phenolic acids. Solid incubation of maize stover with the selected fungi for 28 days resulted in extensive degradation of cell-wall-bound FA and PCA. However, complete degradation of cell wall FA and PCA did not occur in maize stover. In contrast to results in pure liquid medium, P chrysosporium degraded only 20% of the initial concentration of cell wall PCA, and was less effective in degrading cell wall FA compared to P brevispora . These results indicate that the white-rot fungi were able to degrade phenolic acids both in pure culture medium and in cell wall matrix of maize stover. Furthermore, P brevispora exhibited stronger ability to degrade cell-wall-bound phenolic acids. Thus, this fungus can be more effective for the enhancement of fibre digestibility.     

大麦酚类化合物及相关酶类的研究进展

大麦作为重要的粮食作物和啤酒酿造原料,其中的酚类化合物及其相关酶类（如酚类合成酶——苯丙氨酸解氨酶,酚类氧化酶——过氧化物酶和多酚氧化酶）对大麦的生长发育起重要的调节和保护作用,而在大麦的加工过程中会影响产品质量,如过氧化物酶和多酚氧化酶的氧化产物（苯醌和聚合产物）直接影响食品的质量。本文综述了大麦籽粒中酚类化合物及相关酶的种类和功能,并分析了对食品工业和啤酒酿造的影响。     

Combined effect of ultrasound and organic acids to reduce Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on organic fresh lettuce

This study was performed to compare the effectiveness of individual treatments (ultrasound and organic acids) and their combination on reducing foodborne pathogens on organic fresh lettuce. Lettuce leaves were inoculated with a cocktail of three strains each of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes and treated with ultrasound (40 kHz) alone, organic acids (0.3, 0.5, 0.7, 1.0, and 2.0% — malic acid, lactic acid, and citric acid) alone and combined with ultrasound and organic acids for 5 min. For all 3 pathogens, the combined treatment of ultrasound and organic acids resulted in additional 0.8 to 1.0 log reduction compared to individual treatments, without causing significant quality change (color and texture) on lettuce during 7 day storage. The maximum reductions of E. coli O157:H7, S. Typhimurium, and L. monocytogenes were 2.75, 3.18, and 2.87 log CFU/g observed after combined treatment with ultrasound and 2% organic acid for 5 min, respectively. Our results suggest that the combined treatment of ultrasound with organic acids was effective at increasing pathogen reduction compared to individual treatments without significantly affecting quality, and demonstrates its potential as a novel method to increase the microbial safety on organic fresh lettuce.     

Bioactivities,biosynthesis and biotechnological production of phenolic acids in Salvia miltiorrhiza

ABSTRACT

Salvia miltiorrhiza (Danshen in Chinese), is a well-known traditional Chinese medicinal plant, which is used as not only human medicine but also health-promotion food. Danshen has been extensively used for the treatment of various cardiovascular and cerebrovascular diseases. As a major group of bioactive constituents from S. miltiorrhiza, water-soluble phenolic acids such as salvianolic acid B possessed good bioactivities including antioxidant, anti-inflammatory, anti-cancer and other health-promoting activities. It is of significance to improve the production of phenolic acids by modern biotechnology approaches to meet the increasing market demand. Significant progresses have been made in understanding the biosynthetic pathway and regulation mechanism of phenolic acids in S.miltiorrhiza, which will facilitate the process of targeted metabolic engineering or synthetic biology. Furthermore, multiple biotechnology methods such as in vitro culture, elicitation, hairy roots, endophytic fungi and bioreactors have been also used to obtain pharmaceutically active phenolic acids from S. miltiorrhiza. In this review, recent advances in bioactivities, biosynthetic pathway and biotechnological production of phenolic acid ingredients were summarized and future prospective was also discussed.     

Phenolic content and antioxidant activity of cantaloupe (cucumis melo) methanolic extracts

The objectives of this study were to determine phenolic content and antioxidant activity of methanolic extracts from different parts of cantaloupe (leaf, stem, skin, seed and flesh). The flesh extract afforded the highest yield (89.6 ± 0.3%) whilst the lowest yield was obtained from the seed (13.7 ± 0.5%) (p < 0.05). The leaf extract showed the highest total phenolic content (26.4 ± 0.3 mg GAE/g extract) and total flavonoid content (69.7 ± 3.37 μg RE/g extract) accompanied with best antioxidant activity through all antioxidant assays (p < 0.05). In addition, the stem extract also exhibited good antioxidant activity. Thus, these results suggest that methanolic extracts of cantaloupe leaf and stem may serve as a potential source of natural antioxidant for food and nutraceutical application.     

Content of amino acids in fresh and frozen and cooked broad bean seeds (Vicia faba var major) depending on cultivar and degree of maturity

In broad been seeds (cultivars Comprimo RS and Threefoldwhite) harvested at four stages of maturity, which corresponded to dry matter content at the levels of I—25%, II—30%, III—35% and IV—40%, the content of amino acids was determined (g 16 g N⁻¹). The determinations concerned raw broad bean and frozen products cooked for consumption. The content of total and essential amino acids was similar in the two cultivars. With increasing maturity the content of total amino acids and essential amino acids varied, showing a tendency to increase between maturity stages I and IV in all the amino acids, except aspartic acid and alanine in Threefoldwhite. In both cultivars the content of cystine and glutamic acid showed the most rapid rise. Compared with raw broad beans, intact seeds cooked for consumption contained more total amino acids. In products of Comprimo RS the total content of amino acids and essential amino acids was similar in intact seeds and in the dehulled seeds. In products from Threefoldwhite the content of total amino acids and essential amino acids was higher in intact seeds than in dehulled seeds except in the most mature sample where these values were similar. The limiting amino acids were methionine with cystine in both raw broad bean and cooked seeds. © 1999 Society of Chemical Industry     

Phenolic acids released from bermudagrass (Cynodon dactylon) by sequential sodium hydroxide treatment in relation to biodegradation of cell types

Sections of solvent-extracted bermudagrass (Cynodon dactylon L Pers) leaf blades were treated sequentially with increasing concentrations of sodium hydroxide. The amounts of saponifiable phenolic acid monomers and cyclobutane dimers released and the digestibility of the treated blades (ie % dry weight loss) were determined. Leaf sections were examined by scanning electron microscopy for biodegradation of cell types and histochemically (light microscopy) for lignin after treatment with sodium hydroxide. Treatment with 0.1 m sodium hydroxide for 1 h resulted in only minor changes from untreated sections. However, this treatment for 24 h released 86% of the ferulic acid, 65% of the dimers, and c 50% of the p-coumaric acid. Digestibility was increased from 6.5% in the untreated control to 56.6%. Substantial loss of the slowly biodegradable tissues (ie epidermis and parenchyma bundle sheath) and partial biodegradation and disruption of the refractory tissues (ie sclerenchyma, xylem and mestome sheath) occurred; histochemical reactions for lignin were less intense after NaOH treatment. Treatment with 1 m sodium hydroxide for 24 h released 50% of the p-coumaric acid and the remainder of the alkali-extractable ferulic acid and dimers, increased digestibility to 72%, and increased biodegradation of mesophyll and phloem. Mestome sheath cell walls only gave a histochemical reaction for phenolics and the reaction was weak after 1 m NaOH treatment. Alkali treatment increased the biodegradation of all cell types, with lignified tissues reduced to single-cell fibres after 1 and 2 m treatments.     

Content of amino acids and the quality of protein in as‐eaten green asparagus (Asparagus officinalis L.) products

The content of amino acids in fresh green spears and in three as‐eaten products was considered, i.e., in fresh asparagus after cooking and in two products obtained from frozen asparagus stored for 12 months at ?20 °C. One of the frozen products was obtained using the traditional method (blanching–freezing–frozen storage) and then cooked. The other was obtained using the modified technology (cooking–freezing–frozen storage); after the storage period the product was defrosted and heated to consumption temperature in a microwave oven. The limiting amino acid of the first order was methionine with cystine, and of the second order leucine. Essential amino acids constituted 40–43% of the total amino acid content. The dominant amino acids were aspartic acid and glutamic acid. The culinary and technological procedures applied brought about a drastic decrease (50–56% in 16 g N) in tyrosine content.     

Biohydrogenation of fatty acids and digestibility of fresh alfalfa or alfalfa hay plus sucrose in continuous culture

The pattern of biohydrogenation of fatty acids from fresh alfalfa or alfalfa hay supplemented with 3 concentrations (0, 4, and 8%) of sucrose was studied at a constant pH of 6.2. Four continuous culture fermenters were used in a 4 × 4 Latin square design to test the hypothesis that fresh forage would increase flow of vaccenic acid (VA) from the fermenters compared with the same forage in hay form and that this difference would be diminished by adding sucrose to the hay diet by changing the bacterial community profile. Effluent was collected from each of the 4 fermenters during the last 3 d of each 10-d period. Nutrient digestibility, volatile fatty acids (VFA), and fatty acids in the effluent were measured. Flow of bacterial organic matter (OM) and neutral and acid detergent fiber and acid detergent fiber digestibilities were higher for fresh alfalfa than alfalfa hay. True OM digestibility of alfalfa hay tended to linearly decrease with sucrose supplementation. However, microbial efficiency and flow of bacterial OM (g/d) linearly increased with sucrose addition. There was no change in total VFA concentration; however, proportion of acetate linearly decreased and proportion of butyrate linearly increased with sucrose addition. Fresh alfalfa increased total biohydrogenation of fatty acids compared with than hay. Vaccenic acid flow (mg/d) was much higher for fresh alfalfa compared with alfalfa hay (216 vs. 41) and VA was the predominant 18:1 isomer, followed by trans-13 18:1; however, sucrose had no effect on VA flow. The percentage of VA (of total trans-18:1) was not different between fresh alfalfa and hay, whereas percentage of trans-10 18:1 was much lower for fresh alfalfa. Therefore, the ratio of VA to trans-10 18:1 was higher for fresh alfalfa. Flow of trans-12 18:1 linearly increased, whereas flows of cis-12 and total cis-18:1 had quadratic responses to sucrose supplementation. Total biohydrogenation and biohydrogenation of linoleic and linolenic acids linearly decreased with sucrose; however, there was no effect of sucrose on total trans fatty acid flow. Sucrose may be more detrimental to the last step of biohydrogenation of VA. The effects of sucrose on biohydrogenation and concentration of VFA may have been caused by a shift in microbial population by mechanisms that are independent of pH.     

顶空固相微萃取气质联用检测生姜挥发性成分

姜是我国传统的香辛料,其风味芳香而辛辣。本采用顶空固相微萃取气质联用(Head Space Solid Phase Microextraction Gas Chromatgraphy-Mass Spectrometry,HS-SPME-GC-MS)分析检测了生姜的挥发性成分,共检测到51种化舍物。大多是单萜、倍半萜烯类化舍物,Z-柠檬醛含量最多,达24．21％。同时也检测到了姜特有的辣味成分-姜醇。