Articles

Optimization of Fermentation Conditions for the Utilization of Brewing Waste to Develop a Nutraceutical Rich Liquid Product

Shilpi Gupta et al. — Tue, 14 May 2013 04:06:35 PDT

Utilization of brewers’ spent grain (BSG), for the development of a fermented liquid product rich in value-added phenolic compounds was investigated. Changes in and liberation of phenolic compounds and antioxidant activity during fermentation of BSG was studied. The effect of various particle size (PS), solid liquid (SL) ratio, fermentation time and rotation speed was optimized using response surface methodology (RSM) for the purpose of improving bacterial growth and the enhancement in the release of polyphenolic compounds. Contour maps generated using the response surface equation showed that the experimental variables significantly affected the response. A production of 10.4 log cfu/ml, 2.95 g/l lactic acid accompanied by a release of 268.6 mg Gallic Acid Equivalent (GAE)/ml of phenolic compounds, 135 mg Quercetin equivalent (QE)/ml of flavonoid compounds, 33.7 mg TE/ml ferric reducing antioxidant power (FRAP) and 75.1% radical scavenging activity (RSA) was obtained with the optimized factors of 19 h fermentation time, 0.25 SL ratio, 85 rpm and 440 μm PS. Shelf life was monitored over a period of 30 days and the product was shelf stable in terms of bioactive components for 15 days. The cell numbers, total phenol content and acidity (in terms of lactic acid) were maintained till 15 days storage period and a reduction was observed only after that.

Isolation and Partial Characterization of Bioactive Fucoxanthin from Himanthalia elongata Brown Seaweed: A TLC-Based Approach

Gaurav Rajauria et al. — Mon, 13 May 2013 02:16:33 PDT

Seaweeds are important sources of carotenoids, and numerous studies have shown the beneficial effects of these pigments on human health. In the present study, Himanthalia elongata brown seaweed was extracted with a mixture of low polarity solvents, and the crude extract was separated using analytical thin-layer chromatography (TLC).The separated compounds were tested for their potential antioxidant capacity and antimicrobial activity against Listeria monocytogenes bacteria using TLC bioautography approach. For bio-autography, the coloured band on TLC chromatogram was visualized after spraying with DPPH and triphenyltetrazolium chloride reagents which screen antioxidant and antimicrobial compounds, respectively, and only one active compound was screened on the TLC plate. Preliminary identification of this active compound was done by comparing its colour and Rf (retention factor) value with the authentic fucoxanthin standard. Further, the active compound was purified using preparative TLC. This purified compound showed a strong antioxidant (EC50: 14.8 ± 1.27 ug/mL) and antimicrobial (inhibition zone: 10.27 mm, 25 ug compound/disc) activities, which were examined by DPPH scavenging and agar disc-diffusion bioassay, respectively. The bioactivity shown by the purified compound was almost similar to the fucoxanthin standard. The characteristic UV-visible and FT-IR spectra of the purified active compound completely matched with the standard. Hence, the main active compound in H. elongata was identified as fucoxanthin.

Degradation Kinetic Modelling of Colour, Texture, Polyphenols and Antioxidant Capacity of York Cabbage after Microwave Processing

Amit Kumar Jaiswal et al. — Mon, 29 Apr 2013 02:51:20 PDT

Vegetables as an essential component of the human diet usually undergo some type of processing before being consumed. In the present study, impact of microwave (MW) processing on various physiochemical properties of York cabbage was studied. York cabbage was processed at 400, 560 and 800W for 0 to 14 min with an increment of 2 min followed by a kinetic study for the degradation of polyphenols, flavonoids, antioxidant capacity, colour and texture were carried out. Results showed that MW processing leads to significant reductions in the texture, colour, polyphenols and antioxidant capacity. For all the MW processing power studied total phenolic content reduced by up to 85-90% while total flavonoid content reduced by up to 60-73% after 14 min of MW processing. These results were further confirmed by HPLC-DAD analysis. Serious losses in the antioxidant capacity (83-98%) were also observed as a result of MW processing as compared to fresh counterparts and a similar trend was observed for firmness, which reduced by up to 58.8-61.6%, and colour up to 15.2-36.9%. First-order reaction model showed a good fit for the different studied parameters, with coefficients of determination (R²) ranging from 0.90 to 0.99, except for texture (firmness) and colour (chroma), which followed zero-order (R²= 0.88-0.98).

Assessing the effect of product variability on the management of the quality of mushrooms (Agaricus bisporus)

Catherine Barry-Ryan et al. — Tue, 23 Apr 2013 04:05:05 PDT

To study the shelf-life of mushrooms, over 25 batches were subjected to three storage temperatures (T) (5, 15 and 25 ◦ C) and three storage relative humidity (RH) levels (70, 80 and 90%). The effect of T and the RH on the kinetics of quality attributes of the batches was studied by measuring water activity, turgor, colour (L, a* and b* in the Hunter Scale) and weight loss of three different tissues (cap, gills and stipe) of the mushroom. Linear mixed effect models, comprising polynomial models to describe quality kinetics and allowing for batch-to-batch and inside-batch nested variabilitystructure, were built. The resulting models described changes in the six quality factors with time, their kinetic dependence on temperature and relative humidity and estimated the variability components in a typical retailer situation. Signiﬁcant quadratic effects, pointing to optimal storage conditions were found for the temperature (L and a values, b value, water activity, turgor and weight) and for the relative humidity (L and a values, b value, water activity and total weight). Optimal storage conditions point to a practice of low temperature and high relative humidity to preserve product weight, although other properties can be optimally preserved using higher storage temperatures and therefore pointing to possible cost savings in storage. Signiﬁcant batch-to-batch and inside-batch variability components were identiﬁed, giving an estimate of the variability expected on the management of different quality attributes of such a biological product in an agricultural retail scenario.

Effect Of Different Rehydration Temperatures On The Moisture And Phytochemical Constituents Of Dried Edible Irish Brown Seaweed.

Sabrina Cox et al. — Thu, 22 Nov 2012 08:30:34 PST

The effect of temperature (20, 40, 60, 80 and 100 °C) on the rehydration kinetics and phytochemical constituents of dried edible Irish brown seaweed, Himanthalia elongata, were studied. The moisture content of fresh and dried seaweed was 4.07 and 0.07 g water/g dry basis, representing a 98.1% reduction in water content. All rehydration moisture curves had a clear exponential tendency, and it was observed that the rehydration time decreased when temperature was increased. Although restoration of the product to its original moisture content was achieved, rehydration resulted in losses in phytochemical content. Moisture equilibrium was achieved fastest at 100 °C (40 min) with losses of 83.2 and 93% in the total phenol and total flavonoid contents, respectively. The moisture content was fitted to empirical
kinetic models; Weibull, Peleg’s, first-order and exponential association. Activation energies of 4.03, 4.28 and 3.90 kJ/mol were obtained for the parameters of Peleg’s, first-order and exponential models, respectively.

Effect Of Processing Conditions On Phytochemical Constituents Of Edible Irish Seaweed Himanthalia Elongata.

Sabrina Cox et al. — Thu, 22 Nov 2012 04:22:10 PST

Seaweed iswell recognized as an excellent source of phytochemicals. This study was a preliminary screening to investigate the effects of various food processing methods on the phytochemicals of Himanthalia elongata. Hydrothermal processing was carried out until an edible texture was achieved. The total phenolic content (TPC) of fresh H. elongata was 175.27 mg gallic acid equivalent (GAE)/100 g fresh weight (FW) while boiling significantly reduced the TPC to 25.4 mg GAE/100 g FW
(P < 0.05).A drying pretreatment before boiling reduced the cooking time therefore leading to less leaching of antioxidants upon boiling. In terms of extract, drying of H. elongata followed by boiling had the most significant effect on the phytochemicals as TPC increased by 174%. Boiled extracts had the most effective 2, 2-diphenyl- 1-picrylhydrazyl scavenging activity (EC50 of 12.5 mg/mL). As a comparison, seaweed subjected to the same treatments was studied in terms of antimicrobial activity.Overall, extracts fromfresh H. elongata achieved the highest inhibition.

Application Of Response Surface Methodology For Studying The Influence Of Hydrothermal Processing On The Phytochemical Constituents Of Irish Edible Brown Seaweed

Sabrina Cox et al. — Thu, 22 Nov 2012 04:02:32 PST

We used response surface methodology to investigate the
effect of time and temperature of hydrothermal processing
(blanching) on the phytochemical content, texture and colour
of a semi-dried brown seaweed ( Himanthalia elongata ). A
central composite design was employed with a hydrothermal
processing time of 10 – 30 min and temperature of 60 – 90 ° C.
Predicted models were found to be signifi cant for total phenolic
content, 2,2-diphenyl-1-picrylhydrazyl radical scavenging
activity, total fl avonoids, total condensed tannins, texture and
colour. The predicted values for each of the responses were
in good agreement with experimental values. Processing time
had the most signifi cant effect on phytochemical constituents
of H. elongata . An acceptable edible texture and colour of
seaweed was also achieved during the blanching procedure.
Thus, central composite design and response surface methodology
can be used to model phytochemical content, texture
and colour of H. elongata while minimising the number of
experiments required. Multiple response optimisation demonstrated
that the phytochemical content of H. elongata may
be maximised by blanching for 20.4 min at 80.5 ° C.

Hyperspectral Imaging for Non-Contact Analysis of Forensic Traces

Patrick Cullen et al. — Thu, 25 Oct 2012 08:37:07 PDT

Hyperspectral imaging (HSI) integrates conventional imaging and spectroscopy, to obtain both spatial and spectral information from a specimen. This technique enables investigators to analyze the chemical composition of traces and simultaneously visualize their spatial distribution. HSI offers significant potential for the detection, visualization, identification and age estimation of forensic traces. The rapid, non-destructive and non-contact features of HSI mark its suitability as an analytical tool for forensic science. This paper provides an overview of the principles, instrumentation and analytical techniques involved in hyperspectral imaging. We describe recent advances in HSI technology motivating forensic science applications, e.g. the development of portable and fast image acquisition systems. Reported forensic science applications are reviewed. Challenges are addressed, such as the analysis of traces on backgrounds encountered in casework, concluded by a summary of possible future applications.

Brewer’s Spent Grain as a Functional Ingredient for Breadsticks

Anastasia Ktenioudaki et al. — Mon, 15 Oct 2012 04:11:17 PDT

Brewer’s spent grain (BSG) was evaluated for its potential as a functional baking ingredient. Scanning electron microscopy (SEM) was used to examine the microstructure of BSG and wheat flours. Baked snacks (breadsticks) were prepared using 15%, 25% and 35% BSG and evaluated for their baking quality and fibre and protein content (over a period of 3 months). The addition of BSG altered the baking characteristics of the breadsticks by affecting their structure and texture. The snacks appeared to lack in cellular structure and crispiness. However, they had quite a stable shelf-life, as changes in texture, moisture and aw progressed at a low rate. Addition of 25% and 35% BSG significantly increased the protein content of the snacks, and addition of 15% BSG more than doubled the content of dietary fibre in the samples.

Water at Room Temperature as a Solvent for the Extraction of Apple Pomace Phenolic Compounds

Sofia Reis et al. — Fri, 12 Oct 2012 08:16:32 PDT

A fractionation method was used for the extraction of phenolic compounds from apple pomace (AP) involving a first extraction with water and subsequent extractions of the same residue with two different organic solvents. The water extracts obtained presented high amounts of phenolic compounds with high antioxidant capacity however, the second and third extractions of the same residue still extracted considerable amounts of remaining phenolic compounds with significant antioxidant capacities. Liquid chromatography – electrospray ionization mass spectrometry (LC-ESI/MS) studies showed water to be a good solvent to extract hydroxycinnamic acids, flavonols, flavanols, dihydrochalcones and flavones present in the AP. However, water was not the ideal solvent to extract the quercetin glycosides and procyanidins.

Nonthermal Plasma Inactivation of Food-Borne Pathogens

N. N. Misra et al. — Tue, 15 May 2012 03:10:39 PDT

Non-thermal plasma (NTP) is electrically energized matter, composed of highly reactive species including gas molecules, charged particles in the form of positive ions, negative ions, free radicals, electrons and quanta of electromagnetic radiation (photons) at near-room temperature. NTP is an emerging nonthermal technology with potential applications for decontamination in the food industries. An upsurge in the research activities for plasma based inactivation of food borne pathogens is evident in the recent years. These studies have shown that NTP can be used for the surface decontamination of raw produce, dried nuts and the packaging materials etc. This paper reviews the action of plasma agents on the microbial classes and describes proven and potential applications in food processing. Novel developments in the technology and a future outlook for the application to foods are discussed.

Antimicrobial, Antioxidant and Free Radical-Scavenging Capacity of Brown Seaweed Himanthalia Elongata from Western Coast of Ireland

Gaurav Rajauria et al. — Tue, 24 Apr 2012 01:26:06 PDT

Water,methanol and mixtures (20–80%) thereof have been used for the extraction of phenolic compounds from Irish brown seaweed Himanthalia elongata for studying its antimicrobial and antioxidant properties.The 60%methanolic extract exhibited significantly (P < 0.05) the highest value of yield (6.8 6 0.24%), total phenol (286.0 6 4.61 mg gallic acid equivalents/g), flavonoid (109.8 6 2.68 mg quercetin equivalents/g) and condensed tannin content (35.6 6 1.03 mgcatechin equivalents/ g). Antimicrobial activity of 60% methanolic extract tested from disc diffusion and broth dilution methods was effective against various food spoilage and pathogenic bacteria studied.The same extract exhibited statistically highest reducing power and antioxidant capacity againstDPPHradical,metal ions, lipid peroxides and hydrogen peroxide radicals. The UV-visible spectroscopy showed absorption maxima at 205 and 260 nm and the presence of hydroxyl group (3,431 cm-1) and an aromatic ring (around 1,465, 1,505 and 1,624 cm-1) in Fourier Transform Infrared spectroscopy, suggested the presence of phenolic compounds in the extract.

Optimization of Lactic Acid Fermentation of York Cabbage for the Development of Potential Probiotic Products

Amit Jaiswal et al. — Tue, 24 Apr 2012 01:17:59 PDT

In the present study, York cabbage was used as the sole substrate for the lactic acid (LA) fermentation with Lactobacillus plantarum. York cabbage was blanched at 95°C for 12min to inactivate surface microflora prior to fermentation. To achieve an optimal fermentation condition which would result in higher release of phytochemicals and antioxidant (AO) capacity in the broth, Box-Behnken design integrating a desirability approach was used. A second-order polynomial equation was developed indicating the effect of solute/liquid ratio, agitation rate and fermentation time on desired parameters. The optimized factors were used for fermenting York cabbage to obtain maximum bacterial growth, LA, polyphenols and AO capacity. There was ≈5 log cfu/ml increment in bacterial growth after fermentation, whereas LA production reached up to 4.97mg/ml. Results showed that fermentation retains 95-98% and 90-95% of TPC and AOC, respectively. During refrigerated storage (4°C), the cell numbers, bioactive components and acidity were maintained till 15 days storage.

Application of Baranyi function to model the antibacterial properties of solvent extract from Irish York cabbage against food spoilage and pathogenic bacteria

Amit K. Jaiswal et al. — Mon, 23 Apr 2012 09:42:59 PDT

Cabbage is a rich source of a number of bioactive compounds such as flavonoids, glucosinolates and their breakdown products which may have antibacterial, antioxidant and anticancer properties. Outer green leaves of York cabbage were extracted with 60% methanol, ethanol or acetone. Antibacterial activities of vacuum dried crude extracts were estimated against a number of Gram-positive and Gram-negative food spoilage and food pathogenic bacteria. The crude extracts showed a broad spectrum of antibacterial activities but 60% methanol extract exhibited the highest antibacterial effect. Complete growth inhibition for Listeria monocytogenes was achieved with an extract concentration of 1.4%, whereas a two-fold concentration was required to achieve a reduction of 75% and 64% for Salmonella abony and Pseudomonas aeruginosa, respectively. For Enterococcus faecalis methanolic extract showed a weak inhibition only (31%). The lower concentrations of methanolic extract from York cabbage prolonged the lag phase and reduced both the exponential growth rate and final population densities of the culture. Survival of the micro-organisms in presence of methanolic extract was mathematically modeled using Baranyi model equations.

Statistical optimization of blanching time and temperature of Irish York Cabbage using desirability function

Amit K. Jaiswal et al. — Mon, 23 Apr 2012 09:42:46 PDT

The effect of different heat treatments, as a means of preprocessing, on the phytochemicals present in Irish York cabbage was studied. A comparison of blanching (by immersing in water) and microwaving (using water as a medium) indicated that microwaving is detrimental to the phytochemicals present in cabbage. To achieve a blanching time and temperature combination that would result in minimal loss of phytochemicals, central composite design that integrates a desirability approach was used. A second-order polynomial equation was developed, indicating the effect of the blanching time and temperature on the total phenol content (TPC), total flavonoid content (TFC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) values. Contour maps generated using the response surface equation showed that the experimental variables significantly affected the response. The optimized factors (85C and 2 min) were used for blanching York cabbage to obtain a TPC, TFC and half maximal effective concentration for DPPH of 31.01 mg gallic acid equivalents/g, 21.2 mg quercetin equivalents/g and 0.93 mg/mL, respectively.

A comparative study on the polyphenolic content, antibacterial activity and antioxidant capacity of different solvent extracts of Brassica oleracea vegetables

Amit K. Jaiswal et al. — Mon, 23 Apr 2012 09:41:44 PDT

Brassica vegetables are rich in polyphenols, flavonoids and glucosinolates. Investigation was undertaken to optimise the best solvents among 60% ethanol, acetone and methanol for the extraction of polyphenols from Brassica vegetables. Furthermore, different properties such as antibacterial activity and antioxidant capacity were also investigated. Results showed that a 60% methanolic extract showed the highest total phenolic content which was 23.6, 20.4 and 18.7 mg gallic acid equivalents (GAE) g−1 extract for broccoli, Brussels sprouts and white cabbage, respectively. The hydroxybenzoic acid content of various solvent extracts ranged from 5.86 to 8.91 GAE g−1 extract for broccoli, 2.70 to 5.44 GAE g−1 extract for Brussels sprouts and 3.69 to 4.86 GAE g−1 extract for white cabbage, while the hydroxycinnamic acid content ranged from 0.78 to 1.26 chlorogenic acid equivalents (CAE) g−1 extract for broccoli, 1.41 to 3.45 CAE g−1 extract for Brussels sprouts and 0.49 to 1.14 CAE g−1 extract for white cabbage. A concentration-dependent antioxidative capacity was confirmed for different reactive oxygen species, and moderate antibacterial activity was observed against a number of Gram-negative and Gram-positive food spoilage and food pathogenic bacteria. Solvents significantly affected polyphenolic content and its different properties, and the methanol was found to be the best solvent for the extraction of polyphenols from studied Brassica vegetables.

Application of Baranyi function to model the antibacterial properties of solvent extract from Irish York cabbage against food spoilage and pathogenic bacteria

Amit K. Jaiswal et al. — Mon, 23 Apr 2012 09:38:11 PDT

Substrate Profiling and Aldehyde Dismutase Activity of the Kvβ2 Subunit of the Mammalian Kv1 Potassium Channel

A. Kumari et al. — Wed, 30 Nov 2011 07:39:17 PST

Voltage-dependent potassium channels (Kv) are involved in various cellular signalling processes by governing the membrane potential of excitable cells. The cytosolic face of these α subunit-containing channels is associated with β subunits that can modulate channel responses. Surprisingly, the β subunit of the mammalian Kv1 channels, Kvβ2, has a high level of sequence homology with the aldo-keto reductase (AKR) superfamily of proteins. Recent studies have shown that Kvβ2 can catalyze the reduction of aldehydes and, most significantly, that channel function is modulated when Kvβ2-bound NADPH is concomitantly oxidized. As a result, the redox chemistry of this subunit is crucial to understanding its role in K+ channel modulation. The present study has extended knowledge of the substrate profile of this subunit using a single turnover fluorimetric assay. Kvβ2 was found to catalyse the reduction of aromatic aldehyde substrates such as 2, 3 and 4-nitrobenzaldehydes, 4-hydroxybenzaldehyde, pyridine 2-aldehyde and benzaldehyde. The presence of an electron withdrawing group at the position para to the aldehyde in aromatic compounds facilitated reduction. Aliphatic aldehydes proved to be poor substrates. We devised a simple HPLC-based assay to identify Kvβ2 reaction products. Using this assay we showed, for the first time, that Kvβ2 can catalyze a slow aldehyde dismutation reaction using 4-nitrobenzaldehyde as substrate and have identified the products of this reaction. The ability of Kvβ2 to carry out both an aldehyde reduction and a dismutation reaction is discussed in the light of current thinking on the role of redox chemistry in channel modulation.

Kinetic Evaluation of Colour, Texture, Polyphenols and Antioxidant Capacity of Irish York Cabbage After Blanching Treatment

Amit K. Jaiswal et al. — Thu, 15 Sep 2011 02:02:48 PDT

In the present work, York cabbage was blanched between 80 to100°C with an increment of 5°C for up to 14 min and kinetics of the different physio-chemical properties were studied. Significant reductions in the texture, color, polyphenols (PPs) and antioxidant (AO) capacity were observed due to blanching. Total phenolic and flavonoid content retained ranged from 19.6-24.5 and 22.0-25.7%, respectively. Heavy losses in the AO capacity also occurred as a result of blanching, which was evident with a loss of 74.0-82.0% in activity as compared to raw York cabbage. Textural studies showed that blanching caused a significant reduction in firmness in the range of 24.0-73.2% and similar trend also observed for color. Kinetic evaluation of degradation was carried out for all the studied quality parameters. The fractional conversion (FC) first-order reaction model showed a good fit for the different studied parameters with the coefficient of determination ranging from 0.892-0.992 except for texture and color, which followed first order and zero order kinetics, respectively. The temperature effect followed the Arrhenius law with activation energy for polyphenolic content, AO capacity, color and texture calculated as 9.22-11.5, 9.05-35.05, 15.73 and 33.8 kJ/mol K, respectively.

Phenolic Composition, Antioxidant Capacity and Antibacterial Activity of Selected Irish Brassica Vegetables

Amit K. Jaiswal et al. — Thu, 01 Sep 2011 02:51:51 PDT

Vegetables belonging to the Brassicaceae family are rich in polyphenols, flavonoids and glucosinolates, and their hydrolysis products, which may have antibacterial, antioxidant and anticancer properties. In the present study, phenolic composition, antibacterial activity and antioxidant capacity of selected Brassica vegetables, including York cabbage, Brussels sprouts, broccoli and white cabbage were evaluated after extraction with aqueous methanol. Results obtained showed that York cabbage extract had the highest total phenolic content, which was 33.5, followed by 23.6, 20.4 and 18.4 mg GAE/g of dried weight (dw) of the extracts for broccoli, Brussels sprouts and white cabbage, respectively. All the vegetable extracts had high flavonoid contents in the order of 21.7, 17.5, 15.4 and 8.75 mg QE/g of extract (dw) for York cabbage, broccoli, Brussels sprouts and white cabbage, respectively. HPLC-DAD analysis showed that different vegetables contain a mixture of distinct groups of phenolic compounds. All the extracts studied showed a rapid and concentration dependent antioxidant capacity in diverse antioxidant systems. The antibacterial activity was determined against Gram-positive and Gram-negative bacteria. York cabbage extract exhibited significantly higher antibacterial activity against Listeria monocytogenes (100%) and Salmonella abony (94.3%), being the most susceptible at a concentration of 2.8%, whereas broccoli, Brussels sprouts and white cabbage had moderate to weak activity against all the test organisms. Good correlation (r² 0.97) was found between total phenolic content obtained by spectrophotometric analysis and the sum of the individual polyphenols monitored by HPLC-DAD.