In this work the effect of the initial nitrogen concentration on the fatty acid methyl ester (FAME) properties namely the saponification number (SN), the iodine value (IV), the cetane number (CN) and the higher heating value (HHV) of bio-oil produced by Chlorella sorokiniana was examined. Also, the lipid and protein content of the biomass of C. sorokiniana and the biomass yield were measured. Anaerobic digestate and glycerol were used to formulate the culture media. The initial concentration of atomic nitrogen varied in the four cultivations and it was equal to 108.2 mg/l, 300 mg/l, 800 mg/l and 2000 mg/l while the initial concentration of carbon was held constant and equal to 13.99 & PLUSMN; 0.1 g/l. As the initial nitrogen concentration was increased, the lipid content decreased while the protein content and the biomass yield increased. Fatty acids (FA) from C10:0 to C26:1 were produced, however, the fatty acids that were found in the highest percentage were C16:0, C16:1, C18:1 and C18: 2. With respect to saturation, monosaturated FA were predominant in all treatments constituting from 55.9% to 59.4% of the total FA, while significant percentages of saturated FA were produced ranging from 24.5% to about 31.1%. With respect to the chain length, medium chain FA predominate constituting from 59.5% to 81.3% of the total FA. The four measured FAME properties, with the exception of the cetane number (CN) for the No = 2000 mg, were within acceptable limits. It was shown that when the nitrogen concentration in the medium increases, while the carbon concentration remains constant, the biomass carbon yield coefficient increases substantially.

The fatty acid (FA) distribution of bio-oil derived from Chlorella sorokiniana and the biodiesel basic properties were examined. C. sorokiniana was cultivated heterotrophically in two growth media: a) glycerol and inorganic salts (GLIN) and b) glycerol and anaerobic digestrate (GLAD). The cultivation took place in 42 L bioreactors. The bio-oil was extracted from the biomass collected. Extraction was performed using a mixture of n-hexane and isopropanol in a 3:2 ratio. The fatty acid (FA) distribution was determined in a gas chromatograph by converting the bio-oil in biodiesel. The fatty acid distribution covered chain lengths from C10 to C26. The great proportion of the FA were of medium chain FA C16-C18 constituting about 85% and 53% of the total fatty acids of the GLIN and GLAD treatments respectively. Also, the distribution of saturated, monounsaturated and polyunsaturated FA differed. The basic properties of the biodiesel such as the density, the kinematic viscosity, the acid value, the cetane number, the iodine value and the heating value were within the range of the respective values from biodiesel obtained from seed oils and differences in the properties of the two treatments were explained in terms of differences in FA distribution.

In the present study the heterotrophic growth of Chlorella sorokiniana and Chlorella kessleri cultivated in a fed-batch mode, using crude glycerol as the sole carbon source, was investigated. The effect of the mode of the organic carbon addition on the lipid and protein content of the biomass, the fatty acid (FAs) distribution of the bio-oil and the fatty acid methyl ester (FAME) properties was studied. The FAME properties namely, the saponification number, the iodine value, the cetane number and the higher heating value, were estimated from empirical equations. The duration all cultivations was 26 d and until the 20th day 800 mL glycerol were added in the cultivation medium (2.3% v/v). For C. sorokiniana, during the cultivation period, 400, 200 and 80 mL glycerol were added in the cultivation medium at 2, 4 and 10 equal intervals respectively. For C. kessleri 400, 200, 100 and 40 mL glycerol were added at 2, 4, 8 and 20 equal intervals, respectively. For C. sorokiniana lipid and protein content ranged from 35.1% to 47.5% and 16.4% to 21.8%, respectively. The percentage of short chain FAs (C10-C14), medium chain FAs (C16-C18) and long chain FAs (>C18) in the total FAs ranged from 6.6% to 19.8%, 80.2% to 91.3% and 0% to 13.1%, respectively. The percentage of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) of the total FAs ranged from 25.9% to 37.2%, 38.4% to 60.0% and 14.1% to 24.4%, respectively. For C. kessleri lipid and protein content ranged from 27.7% to 35.1% and 21.5% to 29.8%, respectively. The percentage of short chain FAs, medium chain FAs and long chain FAs of the total FAs ranged from 15.8% to 30.6%, 66.2% to 76.8% and 1.9% to 14.7%, respectively. The percentage of SFAs, MUFAs and PUFAs of the total FAs ranged from 38.7% to 54.1%, 40.7% to 53.1% and 5.2% to 16.3%, respectively. Although the treatment 2 x 400 mL of glycerol shows very good FAME properties for both species, the lipid productivities of C. sorokiniana are higher compared to those of C. kessleri and thus, C. sorokiniana is a better option compared to C. kessleri for potential use in biodiesel production.

The growth kinetics and the lipid and protein content of the microalgal species Chlorella sorokiniana (CS) grown heterotrophically in growth media containing glycerol and increasing amounts of anaerobic digestate (AD) equal to 0%, 15%, 30%, and 50% was studied. The effect of the AD on the fatty acid (FA) distribution of the bio-oil extracted from the CS, as well as on the fatty acid methyl ester (FAME) properties such as the saponification number (SN), the iodine value (IV), the cetane number (CN), and the higher heating value (HHV) was also estimated. The percentage of AD in the growth medium affects the rate of carbon uptake. The maximum carbon uptake rate occurs at about 30% AD. Protein and lipid content ranged from 32.3–38.4% and 18.1–23.1%, respectively. Fatty acid distribution ranged from C10 to C26. In all AD percentages the predominant fatty acids were the medium chain FA C16 to C18 constituting up to about 89% of the total FA at 0% AD and 15% AD and up to about 54% of the total FA at 30% AD and 50% AD. With respect to unsaturation, monounsaturated FA (MUFA) were predominant, up to 56%, while significant percentages, up to about 38%, of saturated FA (SFA) were also produced. The SN, IV, CN, and HHV ranged from 198.5–208.3 mg KOH/g FA, 74.5–93.1 g I/100 g FAME, 52.7–56.1, and 39.7–40.0 MJ/kg, respectively. The results showed that with increasing AD percentage, the CN values tend to increase, while decrease in IV leads to biofuel with better ignition quality.

The fatty acid (FA) distribution of bi-oil derived from Chlorella sorokiniana and FAME basic prop-erties were examined. C. sorokiniana was cultivated heterotrophically in two very different growth media: a) glycerol and inorganic salts (GLIN) and b) glycerol and anaerobic digestate (GLAD), as well as in two different modes: a) semi-batch (GLIN) and b) batch (GLAD). The culti-vation took place in 42 L bioreactors and from the biomass collected the bio-oil was extracted, converted to the corresponding fatty acid methyl esters (FAME) and subsequently their distribu-tion was determined in a gas chromatograph. The protein and lipid content were also determined and were used for the estimation of the carbon yield coefficients, which are equal to 0.13 and 0.25 for the GLIN and GLAD treatments respectively. The fatty acid distribution covered chain lengths from C10 to C26. The great proportion of the FA were of medium chain FA C16-C18 con-stituting about 85% and 53% of the total fatty acids of the GLIN and GLAD treatments respec-tively. Also, the distribution of saturated, monounsaturated and polyunsaturated FA differed. The basic properties of the biodiesel such as the density, the kinematic viscosity, the acid value, the cetane number, the iodine value and the heating value are within acceptable ranges and differ-ences in the properties of the two treatments are due to differences in FA distribution.

The aim of this work was to investigate the kinetics of the heterotrophic growth of Chlorella vulgaris as a means of producing bio-oil for biodiesel production. Glycerol was used as the sole organic carbon substrate. Anaerobic digestrate from a local plant was used to examine its effect on the kinetics and the protein and lipid content of the biomass. The effect of the initial carbon and nitrogen concentrations on the carbon uptake rate was studied independently. In one set of five experiments the organic carbon in the form of glycerol, varied from 0.27 g L -1 to 5.36 g L -1 while the concentration of atomic nitrogen was held constant and equal to 45.4 mg L -1 . The Co/No ratio varied from 6 to 118.1. In a second set, also of five experiments, the organic carbon was held constant and equal to 3.3 g L -1 and atomic nitrogen varied from 22.7 mg L -1 to 450 mg L -1 . The Co/No ratio varied from 7.3 to 145.4. In a third set of experiments anaerobic digestrate was added in increasing amounts into the culture media from 4% to 16%. It was found that the carbon uptake rate as well as the lipid and protein content depended on the Co/No ratio. Increasing ratios of Co/No lead to higher carbon uptake rates, higher lipid content and lower protein content. The initial nitrogen concentration was also found to affect the growth rate of C. vulgaris. The addition of anaerobic digestrate did not affect appreciably the protein and lipid content of the biomass while, addition of anaerobic digestrate up to 16% in the culture medium increased the carbon uptake rate up to about 24%.

The aim of this work was to investigate the kinetics of the heterotrophic growth of Chlorella vulgaris as a means of producing bio-oil for biodiesel production. Glycerol was used as the sole organic carbon substrate. Anaerobic digestate from a local plant was used to examine its effect on the kinetics and the protein and lipid content of the biomass. The effect of the initial carbon and nitrogen concentrations on the carbon uptake rate was studied independently. In the one set of five experiments, the organic carbon in the form of glycerol varied from 0.27 to 5.36 g L−1, while the concentration of atomic nitrogen was held constant and equal to 45.4 mg L−1. The Co/No ratio varied from 6 to 118.1. In the second set, also of five experiments, the organic carbon was held constant and equal to 3.3 g L−1 and atomic nitrogen varied from 22.7 to 450 mg L−1. The Co/No ratio varied from 7.3 to 145.4. In the third set of experiments, anaerobic digestate was added in increasing amounts into the culture media from 4 to 16%. It was found that the carbon uptake rate as well as the lipid and protein content depended on the Co/No ratio. Increasing ratios of Co/No led to higher carbon uptake rates, higher lipid content, and lower protein content. The initial nitrogen concentration was also found to affect the growth rate of C. vulgaris. The addition of anaerobic digestate did not affect appreciably the protein and lipid content of the biomass, while the addition of anaerobic digestate up to 16% in the culture medium increased the carbon uptake rate by about 24%.

Currently, there is a great interest in the production of animal feed with antioxidant activity. The aim of this study was to examine the potential antioxidant effects of a feed supplemented with grape pomace (GP), a winery by-product with high environmental load, in chickens. Broilers of 15 days post birth were separated into two groups fed either with standard diet or with diet supplemented with GP for 35 days. Blood and tissues collections were performed after feeding for 15 and 35 days with the experimental diet (i.e. at 30 and 50 days post birth). Free radical toxicity markers, namely thiobarbituric acid reactive substances, protein carbonyls, total antioxidant capacity, reduced glutathione, catalase activity and rate of H2O2 decomposition were determined in blood and tissues of vital organs. The results indicated that feed supplemented with GP decreased oxidative stress-induced toxic effects and improved chickens' redox status, and so it may also improve their wellness and productivity. On the other hand, this exploitation of GP may solve problems of environmental pollution in areas with wineries.

The aim of the present study was to examine the effectiveness of a new redox status marker, the static oxidation reduction potential (sORP), for assessing oxidative stress in 75 patients with metabolic syndrome (MetS) and type 2 diabetes (T2D). A total of 35 normal subjects were used as the controls. Moreover, conventional markers of oxidative stress were assessed, such as thiobarbituric acid reactive substances (TBARS), protein carbonyls, the total antioxidant capacity in plasma, glutathione (GSH) levels and catalase (CAT) activity in erythrocytes. The results revealed that sORP was significantly higher (by 13.4%) in the patients with MetS and T2D compared to the controls, indicating an increase in oxidative stress. This finding was also supported by the significantly lower levels (by 27.7%) of GSH and the higher levels (by 23.3%) of CAT activity in the patients with MetS and T2D compared to the controls. Moreover, our results indicated a great variation in oxidative stress markers between the different patients with MetS and T2D, particarly as regards the GSH levels. Thus, the patients with MetS and T2D were divided into 2 subgroups, one with low GSH levels (n=31; GSH <3 µmol/g Hb) and another with high GSH levels (n=35; GSH >4 µmol/g Hb). The comparison of the markers between the 2 subgroups indicated that in the low GSH group, the GSH levels were significantly lower (by 51.7 and 52.9%) than those in the high GSH group and the controls, respectively. Furthermore, sORP in the low GSH group was significantly higher (by 8.1%) compared to the high GSH group, suggesting its sensitivity for assessing oxidative stress in patients wtih MetS and T2D. Moreover, this variation in oxidative stress levels between the different patients with T2D suggests that the assessment of the redox status may be important in prediabetic conditions, since there is evidence indicating that differences in the redox status in pre-diabetes may result in different outcomes.

In the present study we investigated the effects of an olive polyphenol-enriched yogurt on yogurt microflora, as well as hematological, physiological and metabolic parameters, blood redox status and body composition. In a randomized double-blind, crossover design, 16 (6 men, 10 women) nonsmoking volunteers with non-declared pathology consumed either 400 g of olive fruit polyphenol-enriched yogurt with 50 mg of encapsulated olive polyphenols (experimental condition-EC) or 400 g of plain yogurt (control condition-CC) every day for two weeks. Physiological measurements and blood collection were performed before and after two weeks of each condition. The results showed that body weight, body mass index, hip circumference and systolic blood pressure decreased significantly (p < 0.05) following the two-week consumption of yogurt regardless of condition. A tendency towards significance for decreased levels of low density lipoprotein (LDL) cholesterol (p = 0.06) and thiobarbituric acid reactive substances (p < 0.05) following two weeks of polyphenol-enriched yogurt consumption was observed. The population of lactic acid bacteria (LAB) and production of lactate in yogurt were significantly enhanced after addition of olive polyphenols, contrary to the population of yeasts and molds. The results indicate that consumption of the polyphenol-enriched yogurt may help individuals with non-declared pathology reduce body weight, blood pressure, LDL cholesterol levels and lipid peroxidation, and promote growth of beneficial LAB.

The aim of the present study was to examine the changes occuring in the redox status in male basketball players at the beginning and end of a highly competitive season. For this purpose, the redox status of 14 professional athletes of a European basketball club was examined at 2 different time points, at the beginning (phase 1) and at the end of the season (phase 2). The redox status was assessed in blood using conventional oxidative stress markers, such as thiobarbituric acid reactive substances (TBARS), protein carbonyls (CARB) and the total antioxidant capacity (TAC) in plasma, as well as glutathione (GSH) levels and catalase (CAT) activity in erythrocytes. Moreover, a new static oxidation-reduction potential marker (sORP) was assessed in plasma. Our results revealed that sORP was significantly increased by 9.6% and GSH levels were significantly decreased by 35.0% at phase 2 compared to phase 1, indicating the induction of oxidative stress due to excessive exercise. Moreover, TAC was significantly increased by 12.9% at phase 2 compared to phase 1, indicating the activation of adaptive responses for counteracting oxidative stress. The CARB and TBARS levels were not significantly altered between the 2 phases, although there was a significant correlation (r=0.798) between the sORP and CARB levels. Furthermore, the variations in these markers between athletes were examined. We found that 3 markers exhibited a similar response between athletes, that is, sORP was increased in all 14 athletes, TAC was increased in 13 and the GSH levels were decreased in 14. However, the other 3 markers (i.e., TBARS, CARB and CAT) exhibited marked variations between the athletes, suggesting that the optimal approach with which to counteract (e.g., antioxidant supplementation) the observed increase in oxidative stress is the individualized examination of the redox status of athletes using a series of markers. This would allow the identification of athletes affected by severe oxidative stress and inflammation, and would thus indicate when necessary intervention measures are required to improve their health and performance.