Aggregation profile, preparation and nutritional characterization of African yam bean (Sphenostylis stenocarpa) acid and salt protein isolates

Aggregation tendencies of African yam bean (Sphenostylis stenocarpa) protein in the various aqueous extraction media with Ca²⁺, Mg²⁺ or at pI (isoelectric point) were determined. Water extractable S. stenocarpa protein aggregates more with addition of either Ca²⁺ or Mg²⁺ than at pI. In alkaline extractants considered (except at pH 10), aggregation tendency of the protein is in the order: pI > Ca²⁺ > Mg²⁺. The protein aggregation trend in salt media is a function of the salt type, aggregation in NaCl solution is of order: Ca²⁺ = pI > Mg²⁺, while in Na₂SO₄, we had pI > Mg²⁺ > Ca²⁺. S. stenocarpa protein aggregation was significantly (P < 0.05) more in Na₂SO₄ than NaCl. The amount of Ca²⁺ required for maximum precipitation of S. stenocarpa from alkaline (water-pH10) extractant was higher than that of Na₂SO₄ and more Ca-proteinate was obtained from the alkaline aliquot. The crude protein of the Ca-proteinates and isoelectric protein isolates obtained from salt and alkaline extract were in the range 71.7–91.8% (dry basis). Protein isolate from alkaline extract had significantly (P < 0.05) higher fat content than the one from salt extract. Isoelectrically precipitated isolates had lower ash content than Ca-proteinates. The percentage ratio of essential to non-essential amino acid was in the range 45–47%. With reference to FAO/WHO standard, the chemical score showed that most of the essential amino acid were in excess, thus, the amino acid distribution of S. stenocarpa protein isolates showed that it can fulfill the essential amino acid requirement of human especially the acid proteins and can be a good protein supplement in food and a wide range of new food products.     

Schinus terebinthifolius Raddi extract and linoleic acid from Passiflora edulis synergistically decrease melanin synthesis in B16 cells and reconstituted epidermis

Several treatments for skin whitening are available today, but few of them are completely adequate, especially owing to the carcinogenic potential attributed to classical drugs like hydroquinone, arbutin and kojic acid. To provide an alternative and safer technology for whitening, we developed two botanical compounds originated from Brazilian biodiversity, an extract of Schinus terebinthifolius Raddi and a linoleic acid fraction isolated from Passiflora edulis oil. The whitening effect of these compounds was assessed using biochemical assays and in vitro models including cellular assays and equivalent skin. The results showed that S. terebinthifolius Raddi extract is able to reduce the tyrosinase activity in vitro, and the combination of this extract with linoleic acid is able to decrease the level of melanin produced by B16 cells cultured with melanocyte‐stimulating hormone. Furthermore, melanin was also reduced in human reconstituted epidermis (containing melanocytes) treated with the compounds. The combination of the compounds may provide a synergistic positive whitening effect rather than their isolated use. Finally, we demonstrated that the performance of these mixed compounds is comparable to classical molecules used for skin whitening, as kojic acid. This new natural mixture could be considered an alternative therapeutic agent for treating hyperpigmentation and an effective component in whitening cosmetics.     

Yield and vitamin C content of tomatoes grown in vermicomposted wastes

Increasing quantities of earthworm digested materials (vermicompost) are being marketed as a peat‐free growth medium for amateur and professional food producers. Several studies indicate that growing tomatoes in peat mixed with low concentrations of vermicompost (10–20% by volume) produced by the earthworm Eisenea fetida increases yield of plants and marketability of fruits. Here we examined the effect of substituting commercial peat‐based compost with four different vermicomposts produced by the earthworm Dendrobaena veneta. Vermicompost was added to peat‐based compost at rates of 0%, 10%, 20%, 40% and 100% (v/v) and the following characteristics of tomato (Lycopersicon esculentum var. Money maker) assessed: germination, yield, marketability, fruit weight and ascorbic acid concentration. Vermicompost significantly increased germination rates (176%) and improved the marketability of fruits at 40% and 100% substitution rates due to the lower incidence of physiological disorders ('blossom end rot' and fruit cracking). Total fruit yield, marketable fruit yield, fruit number, individual fruit weight and vitamin C concentration were unaffected by the presence of vermicompost. Although vermicompost may provide a viable alternative to peat‐based growth media, overall, we found little added benefit from using vermicompost. We conclude that some of the previously reported benefits of vermicompost on horticultural production may be overstated and that marketing strategies should reflect this in order to preserve consumer confidence in vermicompost products. Copyright © 2007 Society of Chemical Industry     

Antibacterial activity and mechanism of the ethanol extracts from Sonchus brachyotus DC.

Sonchus brachyotus DC. (S. brachyotus) is considered a vegetable, and rarely considered to be medicinal. However, S. brachyotus is used as a kind of traditional folk herb in Europe. Pharmacological studies are necessary in order to provide a scientific basis to substantiate their use. This study investigated the antimicrobial effect and mechanism of action of the ethanol extract from S. brachyotus. Ethanol extract from S. brachyotus exhibited antimicrobial activity against Escherichia coli, Enterobacter cloacae, Klebsiella pneumonia, Salmonella enteric, Staphylococcus aureus, and Micrococcus luteus; this is especially so in the case of E. coli. This study investigated the novel antibacterial mechanism of ethanol extract from S. brachyotus that shows an apoptosis-like response in E. coli. At all the tested concentration, it was found that ethanol extract from S. brachyotus–treated E. coli cells displayed various apoptotic markers, such as membrane damage, reactive oxygen species accumulation, and membrane depolarization. Expression of caspases protein, which mediates a bacterial apoptosis–like response, was also increased by ethanol extract from S. brachyotus. In order to evaluate the influence of caspases on the appearance of other apoptotic markers, phosphatidylserine exposure and DNA fragmentation were detected and compared with untreated and with ethanol extract from S. brachyotus. These characteristics were detected in E. coli cells, but not in untreated, with ethanol extract from S. brachyotus. In conclusion, the data obtained demonstrated that ethanol extract from S. brachyotus induces an apoptosis-like response in E. coli that associates with caspase-like protein.     

Utilization of waste loquat (Eriobotrya Japonica Lindley) kernels as substrate for scleroglucan production by locally isolated Sclerotium rolfsii

Present study mainly focused on investigating the feasibility of waste loquat kernels as substrate in submerged culture of Sclerotium rolfsii MT-6 for scleroglucan production. Loquat kernel contained high protein (22.5%) and total carbohydrate (71.2%) contents. Dried and powdered kernels were subjected to acid hydrolysis with 2 N HCl. The obtained hydrolysate was used for the preparation of loquat kernel extract (LKE) and detoxified loquat kernel extract (DLKE). S. rolfsii MT-6 was isolated from fermented squash (Cucurbita pepo). Optimal conditions for scleroglucan production were initial pH 5.0, shaking speed 150 rpm, 28°C, and cultivation time of 72 hr. Production media prepared with DLKE or LKE gave maximum biomass concentrations of 17.06 and 16.21 g/L, and maximum scleroglucan concentrations of 12.08 and 10.53 g/L, respectively. DLKE was also favorable substrate for mycelial growth in a uniform pellet form. This is a first report on the application of waste loquat kernels as scleroglucan production substrate and on the use of a local S. rolfsii isolate for this purpose.     

Cultivation of Pleurotus ostreatus mushroom in peat

Pleurotus ostreatus (oyster mushroom) was cultivated in a peat moss based substrate. Acid-hydrolysed peat and non-hydrolysed peat were used in the preparation of the spawn and in the further stage of growing the mushroom fruiting bodies. For comparison, P. ostreatus was also cultivated on paper. Three harvests of mushrooms were obtained in 45 days. The highest total yield gave 10% conversion of peat substrate into mushroom biomass. The mushrooms had 36% crude protein content and all the essential amino acids were present.     

Characterization of an active GST-human Cdc2 fusion protein kinase expressed in the fission yeast Schizosaccharomyces pombe: A new approach to the study of cell cycle control proteins

Characterization of cdk (c yclin d ependent k inases) substrates and studies of their regulation require purified enzymatic complexes of cdc2-related catalytic and cyclin regulatory subunits. We produced human Cdc2 kinase in the fission yeast Schizosaccharomyces pombe as a fusion protein with glutathione S-transferase (GST). The GST-human Cdc2p fusion protein was active in vivo since it rescued a temperature-sensitive allele of cdc2. The fusion protein was purified using a one-step chromatography procedure with glutathione–Sepharose and exhibited a catalytic activity in vitro. Yeast cyclin B and suc1 were found in association with GST-Cdc2. A 17-fold stimulation of GST-Cdc2 kinase activity was obtained by incubation of recombinant human cyclin A with the S. pombe cellular extract prior to affinity purification. This indicates that cyclin concentration is limiting in this overexpression system. These findings describe a fast and easy production of active recombinant human Cdc2 kinase in yeast that can be used for biochemical studies.     

Partial characterization of a lipoxygenase from fusarium proliferatum

Summary

Biomass of the fungus Fusarium proliferatiim was produced and used to obtain a crude extract (FI) of lipoxygenase. The enzyme was further purified by ammonium sulfate precipitation at 40% of saturation (FII). The enzymatic extract (FII) showed its optimum activity at pH 6.0. The apparent K _m and V _max values for the lipoxygenase (FII) were calculated to be 5.15 × 10^?5 M and 1.61 μmol hydroperoxide/mg protein/min, respectively. Enzyme activity remained relatively stable at potassium cyanide concentrations as high as 60 mM. The presence of 5 mM ethylenediaminetetraacetate activated the enzyme by 50%, whereas the use of 1.2 mM hydroquinone resulted in a 2‐fold increase in lipoxygenase activity. The partially purified enzyme (FII) showed a three‐fold enhancement of activity towards linoleic acid compared to linolenic acid as well as mono‐, di‐ and trilinolein.     

Potent Anticariogenic Activity of Aceriphyllum rossii and Its Components,Aceriphyllic Acid A and 3-oxoolean-12-en-27-oic Acid

ABSTRACT: Aceriphyllum rossii Engler (Saxifragaceae) have been used as a nutritious food in Korea. We found that the methanol extract of A. rossii root and its components, aceriphyllic acid A and 3-oxoolean-12-en-27-oic acid, potently inhibited the growth of the key cariogenic bacteria, Streptococcus mutans, with MIC of 2 to 4 μg/mL. They also showed antibacterial activity against other cariogenic bacteria such as S. oralis, S. sobrinus, and S. salivarius with the similar potency . In the time-kill study, aceriphyllic acid A reduced the viable counts of S. mutans by 90% in 1 min at 8 μg/mL, indicating that aceriphyllic acid A had the fast bacteriostatic activity. Severe damages of the cell surface of S. mutans by aceriphyllic acid A were observed by transmission electron microscopy, suggesting with its fast antibacterial activity that its mechanism of action might be membrane disruption. These results suggest that the methanol extract of A. rossii root and its components, aceriphyllic acid A and 3-oxoolean-12-en-27-oic acid, could have the great potential as natural agents for preventing dental caries.     

Utilization of <Emphasis Type="Italic">Echium amoenum</Emphasis> Extract as a Growth Medium for the Production of Organic Acids by Selected Lactic Acid Bacteria

Gol-gavzaban (Echium amoenum Fisch. & Mey.) is an indigenous herbal plant, related to the Boraginaceae family, cultivated historically in Iran. In this study, the suitability of Echium extract as a raw material for production of fermented juice by four strains of lactic acid bacteria (Lactobacillus paracasei, Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus delbrueckii) was examined. Echium extract was inoculated with these bacteria and incubated at 30 °C for 24 h. Changes in microbial population, pH, acidity, sugars, and organic acids metabolism were measured during the fermentation process. Results showed that all of the selected bacteria were capable to grow well in Echium extract without any supplementation. They all metabolized sugars including glucose, fructose and sucrose simultaneously. L. paracasei showed more affinity to sugar consumption at almost 45.2%, 38%, and 21.6% of initial glucose, fructose, and sucrose concentration, respectively. Lactic acid was produced immediately after the fermentation started. L. plantarum, L. delbrueckii, and L. acidophilus produced 6.8, 6.6, and 6.4 g/l lactic acid, respectively, which were significantly higher than that produced by L. paracasei (5 g/l). On the other hand in the case of acetic acid, L. paracasei produced significantly greater quantities in comparison with other strains (4.48 g/l). It was proved that E. amoenum was a desirable media for the production of some organic acids by all these bacterial strains.     

Comparative efficacy of actinidin from green and gold kiwi fruit extract on in vitro simulated protein digestion of beef Semitendinosus and its myofibrillar protein fraction

This study was conducted to evaluate the comparative efficacy of actinidin from green and gold kiwifruit extract on in vitro simulated gastrointestinal protein digestion of cooked beef Semitendinosus and its myofibrillar protein fraction. Samples collected during gastrointestinal digestion were analysed for protein profile, protein digestibility (%), soluble protein (%) and free amino acid analysis. The addition of kiwifruit extracts significantly (P < 0.05) increased protein digestibility, soluble protein and free amino acids released during in vitro gastrointestinal digestion. The in vitro digestibility (%) of the meat samples digested along the green or the gold kiwifruit extract was 2.08% and 3.47% higher than control samples respectively. The soluble protein (%) of the meat samples digested along the green kiwifruit extract was significantly (P < 0.05) higher (18.28%) than control samples (13.03%) after gastrointestinal digestion. Comparatively, actinidin from green kiwifruit extract was more effective than gold kiwifruit extract.     

The ability of Schisandra chinensis fruit to inhibit the growth of foodborne pathogenic bacteria and the viability and heat resistance of Bacillus cereus spores

The objective of this study was to investigate the influence of Schisandra chinensis fruit on the growth of spoilage and pathogenic bacteria and on the viability and heat resistance of Bacillus cereus spores. Schisandra chinensis fruit was extracted with one of three different solvents (50% ethanol, 100% ethanol and distilled water), and the extracts exhibited antimicrobial activity against all the bacteria tested. Particularly, the ethanol extracts of S. chinensis fruit had the strongest activity, in a concentration‐dependent manner. Fractionation of extracts by ion chromatography revealed that the antimicrobial activity of S. chinensis fruit is mainly due to organic acids such as citric acid and malic acid. Meanwhile, S. chinensis fruit extract (10%) significantly reduced the viability and heat resistance of B. cereus spores. Therefore, this study suggests that S. chinensis fruit extract has potential as a natural food preservative and/or sanitising agent for the reduction of spoilage and pathogenic contamination.     

Composition of Saccharomyces fragilis biomass grown on lactose permeate

Saccharomyces fragilis (NRRL y 1109) was grown on a medium composed of Cheddar cheese whey ultrafiltration permeate, supplemented with inorganic nitrogen. The biomass had a crude protein content of 49.5% and an ash content of 7.6%. The “true protein” content, based on a N fractionation procedure was 37.2% and the total nucleic acid content was 5.7%. Qualitatively, the amino acid composition of S. fragilis was similar to that reported for other whey-yeasts. The quantity of individual essential amino acids was greater in the permeate grown S. fragilis. The sulphur containing amino acids, methionine and cyst(e)ine were present at a combined level of 3.2 g/16g N, compared with 2.2g/16 g N in a commercial whey-yeast product. The chemical score (CS) and essential amino acid index (EAAI) were 58.2 and 76.0 respectively. Rats fed on a diet containing S. fragilis biomass as the sole source of dietary protein showed a net weight increase. NPU_carcass for S. fragilis protein was 67.0±3.9 compared with a value of 75.3±3.0 for a casein control. Supplementation of S. fragilis biomass with DL-methionine(2 g/16 g N) raised the NPU_carcass value to 84.4 ± 2.8.     

Emulsifying properties of soy protein isolate fractions obtained by isoelectric precipitation

Soy protein isolate (SPI) fractions were produced by isoelectric precipitation based on results of isoelectric focusing carried out on the crude soy extract. The fractions were produced from crude protein extract (pH 9.0) sequentially and non‐sequentially at isoelectric points (pIs) of 5.6, 5.1 and 4.5. Emulsions stabilised by soy proteins with pIs between 5.6 and 5.1 had the highest (P < 0.01) emulsion stability index (ESI), while those stabilised with proteins having pIs between 5.1 and 4.5 resulted in the lowest ESI for sequentially precipitated fractions. Non‐sequential fractionation at pI 5.1 produced fractions with higher emulsifying activity index (EAI) than sequential fractionation. SDS‐PAGE profiles indicated that the fractions exhibiting high functionality in terms of ESI and EAI were also richer in 7S globulin protein subunits. © 2001 Society of Chemical Industry     

Antibacterial Effect of Glucose Oxidase on Growth of Pseudomonas fragi as Related to pH

The effect of glucose oxidase (GOX) catalyzed reaction with glucose on Pseudomonas fragi was analyzed in nutrient broth and fish extract media. Growth of P. fiugi in nutrient broth was clearly suppressed by 1.0, 2.0 and 4.0 mg/mL glucose when combined with 0.5–2.0 U/mL GOX. The same GOX/glucose combinations inhibited P. frasi growth in fish extract media. Viable cell numbers in fish media showed clear growth inhibition with combinations of l.0–2.0 U/mL GOX and 8.0–16.0 mg/mL glucose. Higher GOX and glucose rapidly produced 2.0–2.5 unit decreases in pH, but produced enough gluconic acid to precipitate fish proteins. Use of 0.5 U/mL GOX in fish extract media resulted in slow, sustained activity with potential for inhibition of microbial growth in foods without excessive acidity.     

Composite malt with dark-purple rice malt improves the phenolic profile and antioxidant activity of malt extract

This research presents a modification of bioactive compounds of malt extract produced from Riceberry rice malt (RRM)–barley malt composite for malt-based beverage. Malt extract was produced by varying RRM at 20% w/w, 40% w/w, 60% w/w, 80% w/w, and 100% w/w and were analysed for total polyphenol content (TPC), phenolic acids constituent, and antioxidant activity. The 100% RRM extract was rich in TPC relative to 100% w/w barley malt extract. The composite malt extract containing 40% w/w–80% w/w RRM had enough TPC in the filtered malt extract (236–524 mg L⁻¹) and boiled hopped malt extract (216–485 mg L⁻¹) and were directly proportional to the antioxidant activity in the extract. Barley malt fraction in the malt extracts had a positive response on ferulic acid and sinapic acid, whereas RRM inclusion in malt extract increased p-coumaric acid, vanillic acid, rutin, and methyl coumarate concentration. Therefore, the cereal malt composite could provide strong oxidative stability to the malt extract and derived products.     

Phytochemicals of ethanolic extract and essential oil of Persicaria hydropiper and their potential as antibacterial agents for food packaging polylactic acid film

This study aims to determine phytochemicals and antibacterial activity of ethanolic extract and essential oil of Persicaria hydropiper, and their potential as antibacterial agents in polylactic acid (PLA) film. The yield of ethanolic extract and essential oil were 11.02 and 0.70%, respectively. Chlorogenic acid, ferulic acid, rutin, myricetin and quercetin were detected as major components in the P. hydropiper ethanolic extract, while dodecanal, caryophyllene, caryophyllene oxide, decanal, α‐caryophyllene, citronellol, heptadecanal, linalool and phytol were detected in the P. hydropiper essential oil. Based on the disc diffusion assay, both ethanolic extract and essential oil of P. hydropiper possessed antibacterial activity against bacteria Staphylococcus aureus only at different concentrations, with minimum inhibitory concentration values: 0.625 and 5 mg/ml, respectively; and minimum bactericidal concentration values: 5 and 40 mg/ml, respectively. However, they found to show antibacterial activity against three bacteria S. aureus, Escherichia coli and Salmonella Typhimurium at different concentrations and time using time‐kill kinetics assay. Incorporation of ethanolic extract and essential oil in PLA film also exhibited an antibacterial effect against S. aureus. Our findings confirmed the potential use of both P. hydropiper ethanolic extract and essential oil as antibacterial agents in biodegradable PLA film.     

Adaptive response and tolerance to weak acids in Saccharomyces cerevisiae boulardii: a metabolomics approach

Weak acids inhibit the growth of probiotics, such as Saccharomyces boulardii. We explored the tolerance of S. boulardii to different weak acids. S. boulardii had better fermentation ability under lactic acid conditions compared with acetic and butyric acid conditions; however, the budding of S. boulardii was significantly stronger than that of Saccharomyces cerevisiae under acetic acid conditions. Although the surface structure of S. boulardii was destroyed, it produced more daughter cells. S. boulardii metabolites were also significantly different from S. cerevisiae under acidic stress. The growth of S. boulardii under weak acid conditions differed significantly from that of S. cerevisiae. S. boulardii-mediated fingerprints under weak acid conditions were identified as latent biomarkers, related to fructose and mannose metabolism, tricarboxylic acid cycle, and the glycolysis pathway. Identified biomarkers will aid in the genetic engineering of S. boulardii and other Saccharomyces strains for improved acid resistance and biomass yield.     

Free D- and L-Amino Acid Evolution During Sourdough Fermentation and Baking

The evolution of free D- and L-amino acids in sourdoughs started with various lactic acid bacteria (LAB) and yeasts was studied. Lactobacillus brevis subsp. lindneri CB1 and Lactobacillus plantrum DC400 had high proteolytic activity. During sourdough fermentation, Saccharomyces cerevisiae 141 and Saccharomyces exiguus M14 sequentially utilized free amino acids produced by bacterial activity. Due to increased cell yeast autolysis, more S. exiguus M14 inocula caused more free amino acids which were partially utilized by LAB without causing hydrolysis of wheat flour protein. D-alanine, D-glutamic acid and traces of other D-isomers were observed in sourdoughs fermented with L. brevis subsp. lindneri CB1 and S. cerevisiae 141. Free total D- and L-amino acid content decreased by more than 44% after baking the sourdoughs. No abiotic generation of new D-amino acid isomers was detected in the baked sourdoughs.     

Improved Acid, Flavor and Volatile Compound Production in a High Protein and Fiber Soymilk Yogurt-like Product

The effects of added caseinate (CAS), casein hydrolyzate (CASHY) and whey protein hydrolyzate (WPHY) on acid, flavor and volatile compound production in a high protein and fiber soymilk yogurt-like product were studied. High protein and fiber soymilk, produced by blending soaked, boiled and dehulled soybeans with Swiss cheese whey ultrafiltration permeate, was fermented with a mixed S. thermophilus and L. bulgaricus yogurt culture. The concentrations of lactic acid, key volatile compounds, i.e., acetaldehyde, acetone, and diacetyl, and the flavor and texture of the resulting soymilk based yogurt formulated with added CAS or CASHY were comparable to those in a milk yogurt control.