Recovery of flavonoids from three-phase olive pomace by aqueous ethanol extraction

A three-phase olive pomace (OP), the solid by-product originating from the production of olive oil, was investigated as a potential source of flavonoids. Flavonoids were extracted by an environmentally friendly procedure using aqueous ethanol as solvent. The flavonoid content of OP, expressed as quercetin equivalents (QE) per unit weight of dry material, was 25.28 ± 0.93 mg QE/g. To evaluate the effects of temperature (T), extraction time (E), liquid-to-solid ratio (R) and solvent composition (C) on the yield of flavonoid extraction (y), a Central Composite Design (CCD) coupled with Response Surface Methodology (RSM) was used. Statistical analysis of the results showed that T was the most influential factor, followed by E, R and C. A reduced polynomial model was developed by the stepwise regression method which provided an accurate description of the extraction process. Maximization of the response variable gave: ymax = 90.5% at T = 69.9 °C, E = 212 min, R = 36.7 mL/g and C = 43.7%. Overall, the obtained results support the use of three-phase OP as a source of flavonoids and give useful indications on the influence of process variables on their recovery

Evaluation of dissolved organic carbon (DOC) as a measure of cell wall degradation during enzymatic treatment of microalgae

The feasibility of using Dissolved Organic Carbon (DOC) measurements as a means to assess the efficacy of an enzyme-assisted pretreatment on the recovery of lipids from microalgae was investigated. Attention was focused on Nannochloropsis sp., a marine microalga of great biotechnological interest for its ability to accumulate large amounts of lipids and other valuable compounds. The enzymatic pretreatment was carried out using two commercial enzyme preparations, one (CEL) rich in cellulase and the other (GMA) rich in galactomannase. Experiments were performed according to a fractional two-level factorial design. The factors studied were temperature (15–75 °C), pH (2–8), pretreatment time (30–270 min), CEL dosage (0–20mg/g) and GMA dosage (0–2 mg/g). DOC was determined by a TOC analyzer and used as the response variable. Under the experimental design conditions, temperature, pH, pretreatment time and CEL dosage were found to be statistically significant (p < 0.05), with the former factor being the most influential. No significant interactions were observed between the main factors, indicating that each of them exerted its effect independently of the others. A good correlation was also found between the measured DOC values and the yields of lipid extraction from the enzymatically treated biomass, demonstrating that DOC measurements can be used to quantify the enzyme-induced degradation of algal cell walls

Extraction of bioactive polyphenols with high antioxidant activity from bilberry (Vaccinium myrtillus L.) processing waste

Bioactive polyphenols were extracted from the peel fraction of bilberry processing waste using aqueous ethanol as solvent. A response surface methodology was used to evaluate the effects of liquid-to-solid ratio (R), solvent composition (C), extraction time (E) and temperature (T) on the extraction yield. The following optimal conditions were determined: R = 30 mL/g, C = 57%, E = 160 min, T = 40 °C. Phenolic extracts with a polyphenol content of 83.75 ± 4.16 mg GAE/g and an antioxidant activity of 7.64 ± 0.43 mmol TE/g were also produced using a batch extractor operating under optimal process conditions

Antibacterial and anti-quorum sensing activities of selected italian honeys against antibiotic-resistant pathogens

Three nectar honeys (eucalyptus, thyme and forest) and two honeydew honeys (fir and Metcalfa) from Italy were tested for their antibacterial activity against pathogens commonly associated with wound and burn infections, including methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE) and vancomycin-resistant Enterococcus faecalis (VREF). All honeys showed bactericidal activity against the microorganisms used, with honeydew honeys being the most effective. They also inhibited, in a dose-dependent manner, violacein production in Chromobacterium violaceum, thus demonstrating their ability to affect quorum sensing-regulated biofilm formation. Overall, the results obtained suggest that the honeys examined may have potential for developing natural antimicrobial compositions or dressings for the treatment of infected wounds or burns

Production of metal nanoparticles by agro-industrial wastes. A green opportunity for nanotechnology

The feasibility of producing silver nanoparticles (Ag NPs) using phenolic extracts from agro-industrial wastes as reducing agents was investigated. Phenolic extracts were obtained from bilberry wastes (BW) and spent coffee grounds (SCG) with aqueous ethanol as extraction solvent. Experiments were carried out in batch at 25 °C by adding appropriate amounts of phenolic extracts to a silver nitrate aqueous solution. The formation of Ag NPs was monitored spectrophotometrically by measuring the intensity of the surface plasmon resonance (SPR) band of silver at 415-435 nm. Depending on the process conditions, the synthesis of Ag NPs was completed in 3 to 5 hours. Characterization of the resulting reaction products by XRD, SEM and DLS showed that nanoparticles were formed with a spherical shape and an average size of 10-20 nm. Overall, the results obtained suggest that BW and SCG could be used as a source of reducing agents for the production of metal NPs and that agro-industrial wastes may represent a valid alternative to the use of microorganisms, whole plants or plant parts for the biogenic synthesis of NPs

Kinetics of lycopene degradation in sunflower and grape seed oils

The stability of lycopene in two vegetable oils, sunflower seed oil (SSO) and grape seed oil (GSO), was investigated by analyzing the carotenoid degradation kinetics in the temperature range of 10–40°C. A tomato oleoresin containing 6% (w/w) of lycopene was used to prepare lycopene-enriched oil samples. Analysis of kinetic data showed that lycopene degradation follows first-order kinetics, with an apparent activation energy of 70.7 kJ mol–1 in SSO and 69 kJ mol–1 in GSO. The estimated half-life of lycopene was found to depend on oil type and storage temperature. At 20°C, it varied between 59 and 122 days, while at 4°C it was comprised between 302 and 650 days. At all temperatures, lycopene was more stable in SSO than in GSO, which is likely due to the higher content of antioxidant compounds in SSO

Improved lycopene extraction from tomato peels using cell-wall degrading enzymes

Four commercial enzyme preparations with pectinolytic, cellulolytic and hemicellulolytic activities were tested for their ability to enhance lycopene extraction from tomato peels. Screening experiments were performed at 25 degrees C by subjecting the peels to a 4-h enzyme incubation followed by 1-h hexane extraction. Peclyve EP and LI were the most efficient, with an almost 20-fold increase in extraction yield. Peclyve LI was used to evaluate the influence of solvent type and enzyme incubation time on lycopene recovery. Hexane, ethyl acetate and the mixture hexane/acetone/ethanol 50:25:25 (v/v) were used as solvents. Under the best extraction conditions (1-h enzyme incubation followed by a 3-h solvent extraction at 40 degrees C) up to 440 mg of lycopene per 100 g of dry tomato peels were obtained. The percentage recoveries were in the range of 3-30%, for the untreated peels, and 77-98% for the enzymatically treated material

Effect of Trehalose on Thermal Stability of Bovine Serum Albumin

Trehalose at 10-30% (w/w) greatly stabilized bovine serum albumin (BSA) against thermal denaturation. The highest stabilization was reached in 30% trehalose at 65 degrees C, when the protein's half life was increased from 72 to 335 min. A kinetic analysis based on the Lumry-Eyring mechanism of inactivation showed that BSA denaturation can be described by a first-order rate expression with an apparent activation energy ranging from 238.1 to 246.4 kJ mol(-1)

Stability and degradation kinetics of lycopene in vegetable oils

The stability of lycopene in sunflower seed oil (SSO), grape seed oil (GSO) and rice bran oil (RBO) was investigated in the temperature range of 10-40 °C. Kinetic analysis of lycopene degradation showed that the process is first-order with respect to the carotenoid concentration, with apparent activation energies between 50.8 kJ mol-1 (RBO) and 70.0 kJ mol-1 (GSO). The half-life of lycopene in the oils was dependent on the storage temperature and varied from 303 to 530 days, at 4 °C, and from 86 to 104 days, at 20 °C. Below 15-20 °C, stability increased in the order: RBO < GSO < SSO, while at higher temperatures such differences tended to disappear. This is likely due to the combined effects of endogenous antioxidants and unsaturated triacylglycerols in the oils on the degradation pathway of lycopene. 2011 Praise Worthy Prize S.r.l. - All rights reserved

Enhanced lycopene recovery from tomato processing waste by enzymatic degradation of plant tissue components

Eight commercial enzyme preparations with pectinolytic, cellulolytic, hemicellulolytic and proteolytic activities were tested for their ability to enhance lycopene extraction from tomato peels. Screening experiments were performed at 40 °C by subjecting the peels to a 1-h enzyme incubation followed by 1-h hexane extraction. The resulting yields were between 51 and 195.9 mg of lycopene per 100 g of dry tomato peels, while the value obtained for the untreated peels was 23.7 mg /100 g. Synergistic and antagonist effects were observed when different enzyme products were used in 50:50 (v/v) combination. The preparations richest in cellulase and pectinase were the most efficient, with an up to 10-fold increase in extraction yield. A statistical analysis of factors affecting lycopene extraction revealed that enzyme dosage was the most influential, followed by temperature and enzyme incubation time. A strong interaction was also found between the latter two variables