Search

Functional black garlic is obtained from fresh garlic (Allium sativum L.) that has been fermented for a period of aging time (35 days) at a controlled high temperature (50–80 °C) under controlled high humidity (85% relative humidity, RH). Subsequently, the Michiu Tou Wine (rice wine) extracts of black garlic was used to determine the allicin, total phenol, and amino acid content. In addition, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capability, trolox equivalent antioxidant capacity, and bacteriostatic capacity of the extract was evaluated. The results found that highest total phenol content was observed in the extracts of black garlic aged at 70 °C. However, the level of pH, water content, allicin content, and free amino acid content decreased with a higher aging temperature. Moreover, DPPH scavenging capability, TEAC, and SOD antioxidant capacity were all enhanced as the aging temperature increased. The black garlic extract aged at 70 °C and 80 °C demonstrated greater bacteriostatic capacity against tested strains. The results revealed that although extracts of both fresh garlic and black garlic possess excellent antioxidant and bacteriostatic capacity, black garlic extract exhibited an even greater capacity in both respects than did fresh garlic extract. The current results of changes in the functional bioactivity during the aging process of garlic, provide useful information for understanding the health benefits and prospect for possible applications as functional food products.

Antifungal activities of the commercial rice wine extracts of Allium fistulosum were analyzed. Antifungal activities were tested against 7 pathogenic fungi by using agar disc diffusion and tube dilution tests. The results show that the commercial rice wine extracts of Allium fistulosum have strong antifungal activity against Aspergillus brasiliensis ATCC 16404, Candida albicans ATCC 10231, Microsporumcanis ATCC 36299, M. gypseum ATCC 24102, Trichophyton mentagrophytes ATCC 9533, T. rubrum ATCC 28188, and T. tonsurans ATCC 28942. The commercial rice wine extracts of different A. fistulosum parts were found to exhibit significant antifungal activities with the minimal inhibitory concentration (MIC) in the range of 0.2 - 1.0 mg/mL. The antifungal activity of the extracts of different A. fistulosum parts was in the order of AFS (stem) > AFI (plant body) > AFL (leaf) > AFR (root).

The antioxidant and antibacterial activities of commercial rice wine extracts obtained from different plant parts of Allium fistulosum were assayed. The results showed that commercial rice wine extracts of A. fistulosum contained 28.3-95.9 μL/mL allicin and exhibited significant antioxidant and antibacterial activities. The DPPH radical scavenging capacity ranged from 90.2% to 52.1%, and the IC50 value ranged from 14.6 to 26.0 μg/mL. The total phenolic content of wine extracts was 56.4-198.9 mg GAE/g extracts. The TEAC assay of extracts ranged from 6.2 to 15.5 mmol/g extracts. Antibacterial activities were tested against 4 bacteria b y using agar disc diffusion and tube dilution tests. All extracts exhibited antibacterial activities against gram-positive bacteria, such as Bacillus subtilis and Staphylococcus aureus, and gram-negative bacteria, such as Escherichia coli and Pseudomonas aeruginosa. Thus, A. fistulosum wine extracts could be used as natural and functional additives in cooking foods.

Linear scan voltammograms of various concentrations of AA and UA was used to test the effect of screen-printed carbon electrode (SPCE) and oxygen plasma-treated SPCErsquos (OP-SPCE) ability to distinguish the oxidative peak potentials (Epa) of UA from AA. The oxygen plasma-treated SPCE (OP-SPCE) could make the oxidative peaks of ascorbic acid (AA) and uric acid (UA) on the linear scan voltammograms became more defined with the Epa to 150 mV (RSD =6.9%,n=7) and 350 mV (RSD =0.6%, n=7), respectively. While measuring a composite solution containing of AA and UA, the AArsquos current signals, generated at the shoulder of the AA peak curve on the linear scan voltammogram caused interference behavior thereby background currents presented to the uric acidrsquos oxidative peak. The degree of background was found proportional to the concentration of AA in the composite solution with a linear regression equation of y = 0.0226x + 2.421 (R2=0.9962). A sequential measurement of ascorbic acid and uric acid concentration in a composition solution by linear scan voltammograms on the plasma treated screen-printed carbon paste electrode has developed: (1) determined the AA concentration (2) determined the degree of interference caused by AA at the uric acidrsquos oxidative peak (3) the estimated interference-free UA peak current is determined by subtracting the level of AA interference. By using the fitting procedure, The UA concentration can be quantitatively and accurately analyzed. Excellent recovery rates (97.9 to 106%) and RSD of 1.4% were obtained for the measurement of UA, even in the presence of high concentrations of AA.

To realize the feasibility of biodiesel production from high-lipid cell culture, microbial lipid production by the oleaginous yeasts was studied using glucose and sucrose as carbon source. Among the tested strains, Cryptococcus sp. SM5S05 accumulated the highest levels of intracellular lipids. The crude lipid contents of Cryptococcus sp. cultured in yeast malt agar reached 30% on a dry weight basis. The accumulation of lipids strongly depended on carbon/nitrogen ratio and nitrogen concentration. The highest content of lipids, measured at a carbon/nitrogen ratio of 60–90 and at a nitrogen concentration of 0.2%, was 60–57% lipids in the dry biomass. Batch cultures using corncob hydrolysate demonstrated that there was minimal inhibitory effect with a reducing sugar concentration of 60 g l −1 or higher. Batch cultures of Cryptococcus sp. SM5S05 in the corncob hydrolysate medium with 60 g l −1 glucose resulted in a dry biomass, lipid yields, and content of 12.6 g l −1 , 7.6 g l −1 , and 60.2%, respectively. The lipids contained mainly long-chain saturated and unsaturated fatty acids with 16 and 18 carbon atoms. The fatty acid profile of Cryptococcus oils was quite similar to that of conventional vegetable oil. The cost of lipid production could be further reduced with corncob hydrolysate being utilized as the raw material for the oleaginous yeast. The results showed that the microbial lipid from Cryptococcus sp. was a potential alternative resource for biodiesel production.

The production of microbial lipids by a batch or fed-batch culture of oleaginous yeast was compared using glucose and corncob hydrolysate as carbon sources. Batch cultures using 4% (w/w) glucose as the carbon source reached a dry biomass, lipid yields and cellular lipid content of 9.4 g/l, 6.0 g/l and 63.5% (w/w), respectively. However, batch cultures demonstrated that there was an inhibitory effect on the biomass and lipid yields when the glucose concentration increased up to 6% (w/w). It was found that the fed-batch culture diminished the substrate’s inhibition of microbial lipid-accumulation. Fed-batch cultures in the corncob hydrolysate-based media containing an initial 4% reducing sugar and an addition 2% glucose for 4 d of cultivation resulted in dry biomass and cellular lipid content of 10.8 g/l and 61.3% (w/w), respectively. The overall lipid productivity increased to 1.08 g/l/d for the fed-batch culture with an initial 4% glucose in corncob hydrolysate and an addition of corncob hydrolysate containing 2% glucose. High concentrations of reducing sugar in the corncob hydrolysate can be efficiently and rapidly converted to Cryptococcus lipid in the fed-batch culture system. Therefore, microbial lipids from Cryptococcus sp. are prospects for a potential alternative oil resource for biodiesel production.

The extracts from different tissues of Allium fistulosum L. and Allium sativum L. were investigated to evaluate their antioxidant and antimicrobial capacity. The highest yields of the Allium extracts were prepared from the extraction of 30% ethanol solution. The DPPH scavenging activity was the highest in A. fistulosum L. leaves, which IC50 is 14.61 μg·mL-1. The highest antioxidant activity using TEAC assay and total phenolic content were observed in A. sativum L. stems and A. fistulosum L. stems, where they are determined to be 15.51 mMand 191.04 mg GAE·g-14.59 mMand 182.60 mg GAE·g-1,respectively. Statistic analysis revealed that the DPPH IC50 value was significantly correlated with total phenolic contents and antioxidant activity using TEAC assay. The extracts of A. sativum L. bulbs were found to exhibit antimicrobial activity against Staphylococcus aureus with the MIC and MBC of 0.2 mg·mL-1and 0.4 mg·mL-1, respectively. In addition, the extract of A. fistulosum L. stems was more active against Bacillus subtilis, with an MIC and MBC of 0.2 and 0.4 mg·mL-1, respectively. The inhibitory activity of various Allium extracts against the test bacteria was greater than that of 10 μg·mL-1 allicin. The results indicated that Allium spp. extracts could be used as a potential source of natural antioxidants and antimicrobial agents.

The optimal conditions for the maximum production of ethanol from cellulosic hydrolysate in batch and fed-batch cultures were investigated and compared. The pretreated corncob could be converted into reducing sugar with maximal yields after the enzyme mixtures were fed. After 48 h of hydrolytic reaction, overall reducing sugar and glucose concentrations reached 0.61 and 0.36 g/g dried substrate, respectively. Further batch fermentation of cellulosic hydrolysate was performed using batch cultures of Saccharomyces cerevisiae BCRC 21812, 23.3–41.1 g/l biomass and 6.9–23.0 g/l ethanol was obtained. For the fed-batch fermentation, the effects of feeding glucose concentrations on ethanol fermentation were studied. The feeding glucose concentration of 30 g/l resulted in a higher ethanol yield than that of 20 g/l and 10 g/l did. The cell biomass, ethanol yields, and ethanol conversion rate for the fed-batch fermentation, feeding at 30 g/l glucose concentration, were 44.5 g/l, 32.3 g/l and 0.64 g ethanol/g glucose, respectively. The results indicate that the fed-batch fermentation had a higher ethanol yield than that of the batch fermentation.

Screen-printed carbon electrodes (SPCEs) were selectively etched by oxygen plasma. The coefficient of variance (CV) of inter-electrode reproducibility was reduced from 21.6 to 4.6. Studies of the surface by color-level-indexing histogram analysis, scanning electronic microscopy (SEM) and resistance revealed that the inter-electrode reproducibility correlated with complete etching of the resin binder from the SPCE surface. The quality of the electrode was differentiated by this color level index analysis. This technique has great potential for application in on-line quality control of the SPCE plasma-treating process when integrated with suitable image processing software.

Production of reducing sugar by hydrolysis of corncob material with Streptomyces sp. cellulase and ethanol fermentation of cellulosic hydrolysate was investigated. Cultures of Streptomyces sp. T3-1 improved reducing sugar yields with the production of CMCase, Avicelase and β-glucosidase activity of 3.8, 3.9 and 3.8 IU/ml, respectively. CMCase, Avicelase, and β-glucosidase produced by the Streptomyces sp. T3-1 favored the conversion of cellulose to glucose. It was recognized that the synergistic interaction of endoglucanase, exoglucanase and β-glucosidase resulted in efficient hydrolysis of cellulosic substrate. After 5 d of incubation, the overall reducing sugar yield reached 53.1 g/100 g dried substrate. Further fermentation of cellulosic hydrolysate containing 40.5 g/l glucose was performed using Saccharomyces cerevisiae BCRC 21812, 14.6 g/l biomass and 24.6 g/l ethanol was obtained within 3 d. The results have significant implications and future applications regarding to production of fuel ethanol from agricultural cellulosic waste.

The antioxidant potentials of buntan pumelo (Citrus grandis Osbeck) and its fermented products were determined. The essential oil from peel had higher total phenolic (214 mM) and flavonoid (134 mg QE/g of dried material) contents than those of different solvent extracts from fruit pulp. In addition, DPPH free radical-scavenging activity and ferric-reducing antioxidant power values determined for the essential oil were 26.1 ± 1.2% and 2.3 ± 0.3 mM, respectively, which were significantly higher than those of various fruit pulp extracts. The ethanol-fermented products of pumelo juice had higher total phenolic and flavonoid contents than those of fresh juice. For maintenance of the substantial antioxidant properties of pumelo products, ethanol-fermented juice rather than fresh or acetate-fermented juice is recommended. Through correlation analysis, the phenolic compounds in the fermented pumelo products were found to be the major contributors to the free radical-scavenging activity and ferric-reducing power.

A novel method for monitoring the growth of coliforms in milk was developed based on measuring the current change in an amperometric sensor. The sensor consists of a circuit with a homemade potentiostat and a pair of electrodes. The electrode was immersed in milk samples containing methylene blue with various concentrations of bacterial inoculums. The microbial metabolism led to the reduction of methylene blue resulting in a change of current. The time required to identify readily detectable change (detection time, DT) provided an approximate measurement of the amount of microorganisms in the initial inoculums. The sensor system used in this study has the selectivity towards coliform bacteria such as Escherichia coli and Enterobacter aerogenes. The calibration curve of DT against concentration of coliform showed a linear correlation coefficient (R2 = 0.9192) over the range of 102–108 CFU/mL. The sensor was able to detect the coliform bacteria at initial concentrations of 105 CFU/mL within 6 h, making it suitable for use in real-time monitoring of bacterial growth. This system has potential application in the detection of coliform concentration in milk at dairy farms when a proper selective media is designed.

A series piezoelectric quartz crystal (SPQC) sensor was developed for quantitative determination of Lactobacillus spp. populations in milk. When the electrodes were immersed in a reaction cell with bacterial inoculum, the change of frequency was caused by the impedance change of the microbial metabolism. A significant frequency decrease was found due to the coagulation of milk when the Lactobacillus spp. was cultivated in the media. The SPQC sensor system established in this study demonstrated the specificity and selectivity for detection of Lactobacillus spp. in milk sample. The calibration curve of detection time against density of Lactobacillus spp. shows a linear correlation coefficient (R 2 = 0.8453) over the range of 102–2.4 × 105 CFU ml−1. The detection time was influenced by the addition of peptone and glucose. The sensor exhibited rapid (within 4 h) and enabled real time monitoring of Lactobacillus spp. growth. This system is potentially applicable to detect Lactobacillus spp. concentration at local farm when a suitable temperature control device is adapted.

To investigate the potential production of polyunsaturated fatty acids (PUFAs), a solid-state column reactor of rice bran with Mortierella alpina was used. The optimal conditions for PUFAs production were rice bran supplementation with 3.75% (ww(-1)) nitrogen source at initial moisture content 57%, initial pH 6-7, aeration, and incubation at 20 degrees C for 5 days and then at 12 degrees C for 7 days. Each gram of substrate carbon yielded 127 mg of total PUFAs, 12 mg of eicosapentaenoic acid (EPA), 6 mg of arachidonic acid (AA), 5mg of alpha-linolenic acid (ALA), and 117 mg of linoleic acid (LA) after 12 days incubation. Aeration enhanced the productions of AA, EPA, and total PUFAs. Supplementation of the nitrogen source on the fourth day and then a shift to lower temperature on the fifth day increased EPA production.

Chinese medicinal plant extracts were screened against some fungal strains, such as Aspergillus niger , Botrytis cinerea , Fusarium moniliforme , Glomerella cingulata , and Phyllosticta caricae . Plants were extracted with hot water, 80% methanol or acetone. Aliquots of the extracts at variable concentrations were then incubated with different fungal strains, and the minimum inhibitory concentrations (MICs) of each plant extract determined. In this study, the methanol extracts of Cinnamomum cassia had MIC values of 13.3 mg ml −1 , when tested against F. moniliforme and P. caricae . The acetone extracts of C. cassia had MIC values of 8.3 mg ml −1 and 10 mg ml −1 respectively, when tested against B. cinerea and G. cingulata . The hot water extracts of C. cassia inhibited significantly the growth of A. niger , B. cinerea , F. moniliforme , and P. caricae with MIC values at 10, 11.7, 5, and 6.7 mg ml −1 respectively. The acetone extracts of Curcuma longa inhibited effectively P. caricae with the MIC value at 6.7 mg ml −1 . To determine the stability, various plant extracts were stored at 4 and 25 °C over a period of one month and their effects on fungal growth examined. Results show that the acetone extracts of Cu. longa and Coptidis rhizoma maintained their activity against fungal strains when stored at 4 °C, but not at 25 °C. The methanol extracts of C. cassia lost a great portion of inhibitory activities but not all, after stored at 4 °C and 25 °C for one month. The effect of various combinations of these extracts on antimicrobial activity has also been examined. The combinations of herb extracts showed higher inhibitory effect towards tested fungi than that of individual extract. Results from these findings suggest that these herbal extracts may be used as natural antifungal agents to inhibit growth of foodborne pathogen.

Hydrogen peroxide (H2O2) residues are not permitted in food due to health concerns. An amperometric sensor based on a Nafion modified palladium (Pd) electrode was developed for the rapid determination of the H2O2 residue in aseptically packaged beverages. A prepared Pd electrode shows a slowly increasing reaction upon repeating the procedure of adding the same concentration of H2O2 into the reaction cell unless pretreating the electrode with cyclic voltammetry to obtain reproducible surfaces, whereas a Nafion modified Pd electrode can reach stable reaction to H2O2 without any pretreatment. The interference level of ascorbic acid (the ration of electrochemical response to ascorbic acid to the electrochemical response of H2O2) was calculated as 0.0004 for the Nafion modified Pd electrode. Interference (99.5%)from ascorbic acid was diminished by Nafion membrane. The response of the sensor to H2O2 in distilled water is linear over the range of 0.25–15 μM (r 2 = 0.9956). The sensor developed in this study can efficiently determine H2O2 residues in commercial beverages with good linear correlation between spiked H2O2 concentration and detected H2O2 concentration, for winter melon-flavored drink, r 2 = 0.9904 in the range of 0.25–15 μM and for lemon-flavored tea, r 2 = 0.9927 in the range of 0.25–25 μM.

The principal antioxidant components and content of cinnamon (Cinnamomum cassia), turmeric (Curcuma longa) and golden thread (Coptidis rhizoma) extracts were determined using high performance liquid chromatography (HPLC) with UV detection. In general, C. cassia, C. longa and C. rhizoma extracts from domestic Taiwan were rich in cinnamaldehyde, curcumin, and berberin, respectively. The contents of cinnamaldehyde, curcumin, and berberin in the acetone extracts were 1911, 2029, and 840 mg l−1, respectively. The Folin–Ciocalteu method was used to measure the total phenolic concentrations of extracts, which had the content of 9.6 (C. cassia), 2.6 (C. longa), and 4.3 (C. rhizoma) mM l−1. In addition, DPPH radical-scavenging, ferric-reducing antioxidant power (FRAP), and ferric thiocyanate (FTC) assays were employed to measure antioxidant activities. The C. cassia fresh extracts had higher antioxidant activities which were 84–90% (DPPH), 17–33 μmol l−1 (FRAP), and 53–82% (FTC). The activities of C. longa fresh extracts were 22–44% (DPPH), 7–11 μmol l−1 (FRAP), and 53–81% (FTC) while C. rhizoma were 53–64% (DPPH), 18–26 μmol l−1 (FRAP), and 59–82% (FTC).

A remote monitoring system based on a piezoelectric quartz crystal (SPQC) sensor was developed for the determination of the bacteria population in raw milk. The system employs the Windows XP server operating system, and its programs for data acquisition, display and transmission were developed using the LabVIEW 7.1 programming language. The circuit design consists of a circuit with a piezoelectric quartz crystal (SPQC) and a pair of electrodes. This system can provide dynamic data monitoring on a web-page via the Internet. Immersion of the electrodes in a cell culture with bacteria inoculums resulted in a change of frequency caused by the impedance change due to microbial metabolism and the adherence of bacteria on the surface of the electrodes. The calibration curve of detection times against density of bacteria showed a linear correlation coefficient ( R 2 = 0.9165) over the range of 70–10 6 CFU ml −1 . The sensor could acquire sufficient data rapidly (within 4 h) and thus enabled real-time monitoring of bacteria growth via the Internet. This system has potential application in the detection of bacteria concentration of milk at dairy farms. © 2005 Elsevier B.V. All rights reserved.

To improve the polyunsaturated fatty acid (PUFA) production by Mortierella, culture media and conditions were investigated. M. alpina ATCC 32222 had the highest yield of arachidonic acid, gamma-linolenic acid and linoleic acid among 11 test microbes. Soluble starch at 10% and the mixture of KNO3 and yeast extract at 2:1 (w/w) was the best carbon and nitrogen sources for arachidonic acid and total PUFAs production, respectively. The optimal C/N ratio ranged from 5.1 to 9.0. Each gram of carbon produced 17.4 mg of linoleic acid, 17.0 mg of gamma-linolenic acid, 103.0 mg of arachidonic acid and 194.2 mg of total PUFAs at 20 degrees C, while it yielded 21.4 mg of linoleic acid, 25.6 mg of gamma-linolenic acid, 2.6 mg of gamma-linolenic acid, 110.3 mg of arachidonic acid, 4.3 mg of eicosapentaenoic acid and 218.4 mg of total PUFAs at 12 degrees C. A high degree of unsaturation was found at low temperature incubation. Linseed oil supplementation (1%, w/v) increased the PUFAs production and each gram of carbon produced 403.4 mg of alpha-linolenic acid, 123.1 mg of arachidonic acid, 33.6 mg of eicosapentaenoic acid, 1.68 mg of docosahexaenoic acid and 943.2 mg of total PUFAs. From the optimization of culture media and conditions, PUFAs production increased from 30% to 5 times that was optimal for practical use.

The flow cytometry (FC) has been used to detect Giardia cysts and Cryptosporidium oocysts quantitatively and instantaneously in this study. The experimental results showed that FC is potential to become a more precise method for the detection of Giardia and Cryptosporidium in water. This study also evaluated the staining efficiencies for three commercial antibodies. After staining Cryptosporidium oocysts with direct immunofluorescent antibodies in water samples, two populations were detected in the scatter-plots (FL1 versus SSC) of the FC. The Cryptosporidium oocysts and Giardia cysts are significantly separated from other particles while stained with direct immunofluorescent antibodies produced by Meridian Diagnostics and Waterborne Inc.

A total of 26 thermophilic isolates, selected from a compost of agricultural waste, which was mostly composed of vegetable, corncob and rice straw, were cultivated at 50 °C for further studies of thermostable cellulase production. The thermostable cellulase gene from the chromosomal DNA of actinomycetes isolate no. 10 was shotgun-cloned and transformed into Streptomyces sp. IAF 10-164. A transformant, T3-1, was found to be a good strain for the production of thermostable cellulases. Cultivation of T3-1 in modified Mandels–Reese broth containing 1% carboxymethylcellulose (CMC)-sodium salt and the optimal condition for microbial growth were studied. Batch cultivation in a flask revealed that CMCase and Avicelase production reached the maximum between the third to fifth day, whereas maximum β-glucosidase production occurred on the ninth day. Microbial biomass increased from the first day to the fifth day and then decreased. The crude enzyme had the highest activity at 50 °C and at pH 6.5. The enzyme was shown to be a thermostable cellulase whose activities were stable at 50 °C for more than 7 days.

Thermostable cellulase was produced by Streptomyces sp. T3-1 grown in a 50-l fermenter. Maximum cellulase activity was attained on the fourth day when agitation speeds and aeration rates were controlled at 300 rpm and 0.75 vvm, respectively. Maximum enzyme activities were: 148 IU CMCase ml(-1), 45 IU Avicelase ml(-1), and 137 IU beta-glucosidase ml(-1) with productivity of 326 IU l(-1) h(-1), which were 10-32% higher than the values obtained in shake-flask cultures.