Phenolics and Antioxidant Properties of Fruit Pulp and Cell Wall Fractions of Postharvest Banana (Musa acuminata Juss.) Cultivars

Banana fruits are important foods, but there have been very few studies evaluating the phenolics associated with their cell walls. In the present study, (+) catechin, gallocatechin, and (-) epicatechin, as well as condensed tannins, were detected in the soluble extract of the fruit pulp; neither soluble anthocyanidins nor anthocyanins were present. In the soluble cell wall fraction, two hydroxycinnamic acid derivatives were predominant, whereas in the insoluble cell wall fraction, the anthocyanidin delphinidin, which is reported in banana cell walls for the first time, was predominant. Cell wall fractions showed remarkable antioxidant capacity, especially after acid and enzymatic hydrolysis, which was correlated with the total phenolic content released after the hydrolysis of the water-insoluble polymer, but not for the posthydrolysis water-soluble polymer. The acid hydrolysis released various monosaccharides, whereas enzymatic hydrolysis released one peak of oligosaccharides. These results indicate that banana cell walls could be a suitable source of natural antioxidants and that they could be bioaccessible in the human gut.

Isoflavones and Antioxidant Capacity of Commercial Soy-Based Beverages: Effect of Storage

Samples of 11 different brands of commercially available soy-based beverages (n = 65), including products made from soy protein isolate (SPI) and soy milk, mixed with fruit juice and/or flavoring, were analyzed for their isoflavone content and in vitro antioxidant activity. There was a large variation in isoflavone and total phenolics contents ranging from 0.7 to 13 mg of isoflavones/200 mL and from 6 to 155 mg equivalents of catechin/200 mL, respectively. The antioxidant activity also varied significantly among products. Storage of the beverages at room temperature caused a significant decrease of antioxidant capacity, soluble phenolics, and isoflavone contents after 9 months. When soybeans used for beverage production were stored for up to 6 months in silos, the resulting products were not affected. However, a decrease of malonyl and a proportional increase of free glucosidic forms of isoflavones were observed after storage of both the raw material and the beverages.

Phenolic compounds in raw and cooked rice (Oryza sativa L.) and their inhibitory effect on the activity of angiotensin I-converting enzyme

Whole rice has been widely studied due to the abundance of bioactive compounds in its pericarp. Some of the beneficial effects of these compounds on human health have been attributed to their antioxidant and other biological activities, such as enzyme inhibition. In this work, we evaluated the contents of total, soluble and insoluble phenolic compounds of 6 red and 10 non-pigmented genotypes of whole rice as well as their inhibitory effect on the activity of angiotensin I-converting enzyme (ACE). The effects of cooking on phenolics and their inhibitory activities were also investigated. Red genotypes showed high content of phenolics, mainly soluble compounds, at an average of 409.7 mg ferulic acid eq./100 g, whereas overall lower average levels (99.4 mg ferulic acid eq./100 g) at an approximate soluble/insoluble compound ratio of 1:1 were observed in non-pigmented rice. Pigmented rice displayed a greater inhibitory effect on ACE than non-pigmented rice. In fact, a significant correlation between the content of soluble phenolics and ACE inhibition was observed (r = 0.8985, p < 0.05). In addition to significantly reducing the levels of total phenolics and ACE inhibition, cooking altered the soluble/insoluble compound ratio, especially among red rice genotypes. (C) 2011 Elsevier Ltd. All rights reserved.

Fresh-cut aromatic herbs: Nutritional quality stability during shelf-life

Fresh-cut vegetables are a successful convenient healthy food. Nowadays, the presence of new varieties of minimally processed vegetables in the market is common in response to the consumers demand for new flavours and high quality products. Within the most recent fresh-cut products are the aromatic herbs. In this work, the objective was to evaluate the nutritional quality and stability of four fresh-cut aromatic herbs. Several physicochemical quality characteristics (colour, pH, total soluble solids, and total titratable acidity) were monitored in fresh-cut chives, coriander, spearmint and parsley leaves, stored under refrigeration (3 ± 1 ºC) during 10 days. Their nutritional composition was determined, including mineral composition (phosphorous, potassium, sodium, calcium, magnesium, iron, zinc, manganese and copper) and fat- and water-soluble vitamin contents. Total soluble phenolics, flavonoids and the antioxidant capacity were determined by spectrophotometric methods. The aromatic herbs kept their fresh appearance during the storage, maintaining their colour throughout shelf-life. Their macronutrient composition and mineral content were stable during storage. Coriander had the highest mineral and fatsoluble vitamin content, while spearmint showed the best scores in the phenolic, flavonoid and antioxidant capacity assays. Vitamins and antioxidant capacity showed some variation during storage, with a differential behaviour of each compound according to the sample.

Influence of wheat straw and rhizosphere on seed germination, early seedling growth and bio-chemical attributes of Trianthema portulacastrum

Decomposing wheat (Triticum aestivum) straw and rhizosphere-infested soil were evaluated for their suppressive activity against horse purslane (Trianthema portulacastrum), a noxious summer weed in Pakistan. Two separate pot studies were carried out. Wheat straw was incorporated at 4, 6 and 8 g kg-1 soil five days before the sowing of horse purslane. Pots without straw incorporation were maintained as control. In a second study, soil was taken from 15 and 30 cm depths from a previously cropped wheat field immediately after its harvest and was used as growing medium. Soil from an intentionally uncropped area of the same field was used as control. Suppressive activity was measured in terms of germination dynamics, seedling growth, and biochemical attributes such as chlorophyll contents, total soluble phenolics, soluble protein and antioxidant enzymes. Germination, seedling growth, chlorophyll contents and soluble protein of horse purslane were all negatively influenced. Higher phenolics and enhanced activities of antioxidant enzymes were noticed in response to wheat residues incorporation and its rhizosphere soil. Both studies established that the phytotoxic influence of wheat straw and wheat-infested rhizosphere soil on horse purslane can further be exploited for horse purslane management as a sustainable approach.

Toxic action of aqueous wheat straw extract on horse e purslane

The toxic action of aqueous wheat (Triticum aestivum) straw extracts was investigated on germination, early seedling growth, some biochemical attributes and the antioxidant enzymes of horse purslane (Trianthemaportulacastrum). Aqueous extracts of wheat straw were prepared by soaking the wheat straw in distilled water in 1:10 w/v ratio and diluted to obtain the concentrations of 0, 25, 50, 75 and 100%. These were used as pre and post emergence in laboratory and screen house trials. Wheat aqueous extracts exhibited phytotoxicity to horse purslane by inhibiting and delaying its germination and suppressing seedling growth. Wheat phytotoxins in its aqueous extracts suppressed the chlorophyll content and soluble protein, and enhanced soluble phenolics and the activity of antioxidant enzymes as catalase, peroxidase and superoxide dismutase in the seedlings of horse purslane compared with the control. Such inhibitory activity is believed to originate from exposure to wheat phytotoxins that are present in its aqueous straw extract. The suppressive effects of wheat straw need to be investigated further under field conditions.

Comparative allelopathic potential of metabolites of two Alternanthera species against germination and seedling growth of rice

A laboratory study was conducted to investigate the allelopathic effect of aqueous extracts of plant parts of Alternanthera philoxeroides and A. sessilis and soil incorporated residues on germination and seedling growth of rice (Oryza sativa). Aqueous extracts prepared from different plant parts of Alternanthera species delayed rice germination. Alternanthera philoxeroides and A. sessilis inhibited rice germination by 9-100% and 4-49%, respectively. Germination of rice seeds was reduced with increasing concentration of aqueous leaf extracts of both weed species. Early seedling growth (root and shoot lengths) and seedling vigor index were significantly reduced by 5% aqueous leaf extract compared with distilled water treated control. Germination, root and shoot lengths, root and shoot dry weights and seedling vigor index of rice were drastically reduced by 3 and 4% in residue infested soil compared with residue free soil. The inhibitory effect of A. philoxeroides in terms of germination and seedling growth of rice was greater than that of A. sessilis. Five percent aqueous leaf extract and 4% residue infested soil of A. philoxeroides caused complete failure of rice seed germination. Alternanthera philoxeroides contained water soluble phenolics, namely 4 hydroxy-3-methoxy benzoic acid (16.19 mg L-1) and m-coumaric acid (1.48 mg L-1), whereas Alternanthera sessilis was rich in chlorogenic acid (17.85 mg L-1), gallic acid (11.03 mg L-1) and vanillic acid (9.88 mg L-1). The study indicates that the allelopathic potential of Alternanthera species may play an important role in enhancing the invasiveness of these species and may suppress rice plants in the vicinity.

Effect of huitlacoche (Ustilago maydis DC Corda) paste addition on functional, chemical and textural properties of tortilla chips

AbstractThis study analyzed the addition of huitlacoche paste (HP) in baked tortilla chips (TC), evaluating its effects on functional, physicochemical and structural changes during processing. Two blue corn grains were nixtamalized, stone milled, air dried and milled to obtain flour; commercial blue corn flour (TM1) and commercial TC (TM2) were used as controls. Additions of 0, 3, 6 and 9% of HP were formulated; masas were prepared at 55% moisture content (MC), precooked and baked in an industrial machine. TC crispiness was influenced by grain characteristics and percentage of HP. Huitlacoche paste addition caused an increase in total dietary fiber (from 5.27 to 14.54%), total soluble phenolics content (from 17.52 to 37.60 mg GAE/100 g) and antioxidant capacity (from 6.74 to 7.98 μmol TE/g) in TC. Results suggest that tortilla chips added with huitlacoche can be an alternative to prepare this traditional edible fungus and produce healthier snacks, not fried and enriched with bioactive compounds.

Chemical composition and in vitro fermentation of tannin-rich tree fruits

Dry and mature tree fruits are a potential source of protein for goats in the semi-arid areas of southern Africa, but their chemical composition and feeding value is largely unknown. This study presents the chemical composition and in vitro fermentation of indehiscent whole fruits and separated seed and hull fractions from Acacia nilotica, Acacia erubescens, Acacia sieberiana, Acacia erioloba, Piliostigma thonningii and Dichrostachys cinerea trees. Results indicate that the N contents of whole fruits ranged between 13.5 g/kg DM (A. nilotica) and 27.1 g/kg DM (A. erubescens). Seeds had a higher N content than hulls for all tree species. A. nilotica, D. cinerea and P thonningii fruits had high levels of extractable phenolics (758, 458 and 299 g/kg DM, respectively). Soluble phenolics (SPh) and ytterbium precipitable phenolics (YbPh) levels were negatively correlated to in vitro gas production but positively correlated to in vitro organic matter degradability (iOMD). Partition factors for whole fruits at 48 h ranged between 3.6 mg/ml for A. erioloba and 7.8 mg/ml for A. nilotica. Seeds of A. erioloba, A. erubescens and P thonningii were consistently fermented more efficiently throughout the incubation period compared to their whole fruits or hulls. Estimating in vitro degradability of phenolic-rich substrates through filtration procedures can give erroneous results due to the loss of soluble phenolics, which are not necessarily degradable. The feeding value of fruits from D. cinerea and A. nilotica tree species may be reduced due to the presence of high levels of phenolics. (C) 2007 Elsevier B.V. All rights reserved.

Impacts of groundwater discharge at Myora Springs (North Stradbroke Island, Australia) on the phenolic metabolism of eelgrass, Zostera muelleri, and grazing by the juvenile rabbitfish, Siganus fuscescens

Myora Springs is one of many groundwater discharge sites on North Stradbroke Island (Queensland, Australia). Here spring waters emerge from wetland forests to join Moreton Bay, mixing with seawater over seagrass meadows dominated by eelgrass, Zostera muelleri. We sought to determine how low pH / high CO2 conditions near the spring affect these plants and their interactions with the black rabbitfish (Siganus fuscescens), a co-occurring grazer. In paired-choice feeding trials S. fuscescens preferentially consumed Z. muelleri shoots collected nearest to Myora Springs. Proximity to the spring did not significantly alter the carbon and nitrogen contents of seagrass tissues but did result in the extraordinary loss of soluble phenolics, including Folin-reactive phenolics, condensed tannins, and phenolic acids by ?87%. Conversely, seagrass lignin contents were, in this and related experiments, unaffected or increased, suggesting a shift in secondary metabolism away from the production of soluble, but not insoluble, (poly)phenolics. We suggest that groundwater discharge sites such as Myora Springs, and other sites characterized by low pH, are likely to be popular feeding grounds for seagrass grazers seeking to reduce their exposure to soluble phenolics.

Soluble proteins and polyphenoloxidase activity in bud flowers, flowers and leaves of cold stored lisianthus

This study evaluated the activity of the enzyme polyphenol oxidase (PPO) and the content of soluble protein present in lisianthus bud flowers, flowers and leaves in room temperature (24±2°C) and pre-exposure cold chamber at 9±2°C for 24 h, in order to examine a possible correlation between these parameters and postharvest longevity of lisianthus flowers. After treatments, flowers were kept in pots with water, stored at room temperature and evaluated every three days until the end of their decorative life for biochemical analyzes. During the experimental period the enzymatic activity increased with the aging of the material, directly related to the high concentration of phenolics that were accumulated in injured tissue, providing browning, while soluble protein content slightly decreased. Thus, PPO enzyme activity can be applied for plant senescence evaluation, acting as a biochemical marker for product visual quality.

Wine phenolics: looking for a smooth mouthfeel

Each grape variety has its own phenolic profile. However, the concentration of the phenolic compounds present in wine mainly dependson winemaking processes. Phenolic compounds influence wine sensorial characteristics namely taste or mouthfeel, bitterness, astringency and color. Humans can perceive six basic tastes: sweet, salty; sour; umami; fat-taste and bitter taste. This last basic taste is considered as a defense mechanism against the ingestion of potential poisons. Some of the genes,encoding G-protein-coupled receptors - TAS2Rs, which translate for these distinct bitter compounds detectors have been identified. Different phenolic compounds activate distinguished combination of TAS2Rs. Astringency in wine is primarily driven by proanthocyanidins, soluble protein-proanthocyanidins complexes which diminish the protective salivary film and bind to the salivary pellicle; insoluble protein-proanthocyanidins complex and proanthocyanidins are rejected against salivary film and trigger astringency sensation via increasing friction. Thus, the aim of this review is to expand the knowledge about the role of wine phenolic compounds in wine sensorial properties, namely in bitterness and astringency phenomenon’s.

The Soluble Guanylyl Cyclase Activator Bay 60-2770 Potently Relaxes The Pulmonary Artery On Congenital Diaphragmatic Hernia Rabbit Model.

Congenital diaphragmatic hernia (CDH) is associated with pulmonary hypertension which is often difficult to manage, and a significant cause of morbidity and mortality. In this study, we have used a rabbit model of CDH to evaluate the effects of BAY 60-2770 on the in vitro reactivity of left pulmonary artery. CDH was performed in New Zealand rabbit fetuses (n = 10 per group) and compared to controls. Measurements of body, total and left lung weights (BW, TLW, LLW) were done. Pulmonary artery rings were pre-contracted with phenylephrine (10 μM), after which cumulative concentration-response curves to glyceryl trinitrate (GTN; NO donor), tadalafil (PDE5 inhibitor) and BAY 60-2770 (sGC activator) were obtained as well as the levels of NO (NO3/NO2). LLW, TLW and LBR were decreased in CDH (p < 0.05). In left pulmonary artery, the potency (pEC50) for GTN was markedly lower in CDH (8.25 ± 0.02 versus 9.27 ± 0.03; p < 0.01). In contrast, the potency for BAY 60-2770 was markedly greater in CDH (11.7 ± 0.03 versus 10.5 ± 0.06; p < 0.01). The NO2/NO3 levels were 62 % higher in CDH (p < 0.05). BAY 60-2770 exhibits a greater potency to relax the pulmonary artery in CDH, indicating a potential use for pulmonary hypertension in this disease.

Bay 41-2272, A Soluble Guanylate Cyclase Stimulator, Relaxes Isolated Human Ureter In A Standardized In Vitro Model.

To characterize the relaxation induced by BAY 41-2272 in human ureteral segments. Ureter specimens (n = 17) from multiple organ human deceased donors (mean age 40 ± 3.2 years, male/female ratio 2:1) were used to characterize the relaxing response of BAY 41-2272. Immunohistochemical analysis for endothelial and neuronal nitric oxide synthase, guanylate cyclase stimulator (sGC) and type 5 phosphodiesterase was also performed. The potency values were determined as the negative log of the molar to produce 50% of the maximal relaxation in potassium chloride-precontracted specimens. The unpaired Student t test was used for the comparisons. Immunohistochemistry revealed the presence of endothelial nitric oxide synthase in vessel endothelia and neuronal nitric oxide synthase in urothelium and nerve structures. sGC was expressed in the smooth muscle and urothelium layer, and type 5 phosphodiesterase was present in the smooth muscle only. BAY 41-2272 (0.001-100 μM) relaxed the isolated ureter in a concentration dependent manner, with a potency and maximal relaxation value of 5.82 ± 0.14 and 84% ± 5%, respectively. The addition of nitric oxide synthase and sGC inhibitors reduced the maximal relaxation values by 21% and 45%, respectively. However, the presence of sildenafil (100 nM) significantly potentiated (6.47 ± 0.10, P <.05) this response. Neither glibenclamide or tetraethylammonium nor ureteral urothelium removal influenced the relaxation response by BAY 41-2272. BAY 41-2272 relaxes the human isolated ureter in a concentration-dependent manner, mainly by activating the sGC enzyme in smooth muscle cells rather than in the urothelium, although a cyclic guanosine monophosphate-independent mechanism might have a role. The potassium channels do not seem to be involved.

Immobilization Of Papain On Chitin And Chitosan And Recycling Of Soluble Enzyme For Deflocculation Of Saccharomyces Cerevisiae From Bioethanol Distilleries.

Yeast flocculation (Saccharomyces cerevisiae) is one of the most important problems in fuel ethanol production. Yeast flocculation causes operational difficulties and increase in the ethanol cost. Proteolytic enzymes can solve this problem since it does not depend on these changes. The recycling of soluble papain and the immobilization of this enzyme on chitin or chitosan were studied. Some cross-linking agents were evaluated in the action of proteolytic activity of papain. The glutaraldehyde (0.1-10% w·v(-1)), polyethyleneimine (0.5% v·v(-1)), and tripolyphosphate (1-10% w·v(-1)) inactivated the enzyme in this range, respectively. Glutaraldehyde inhibited all treatments of papain immobilization. The chitosan cross-linked with TPP in 5 h of reaction showed the yield of active immobilized enzyme of 15.7% and 6.07% in chitosan treated with 0.1% PEI. Although these immobilizations have been possible, these levels have not been enough to cause deflocculation of yeast cells. Free enzyme was efficient for yeast deflocculation in dosages of 3 to 4 g·L(-1). Recycling of soluble papain by centrifugation was effective for 14 cycles with yeast suspension in time perfectly compatible to industrial conditions. The reuse of proteases applied after yeast suspension by additional yeast centrifugation could be an alternative to cost reduction of these enzymes.