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Markou G.,Institute of Soil and Water Resources | Markou G.,Agricultural University of Athens | Iconomou D.,Institute of Technology of Agricultural Products | Muylaert K.,Catholic University of Leuven
Algal Research | Year: 2016

In the present paper, the use of raw poultry litter (PL) as a nutrient source for the cultivation of Arthrospira platensis and Chlorella vulgaris was investigated. PL was added to acid solution (62.5 mM H2SO4) for the extraction of nutrients contained in PL. After settling, the supernatant, called PL leachate (PLL) was diluted 25×, 20×, 15×, and 10× and used as a mediumfor the cultivation of A. platensis and C. vulgaris. A. platensis could not survive in 15× and 10× diluted leachate andwhile in 20× and 25× dilutions the biomass production was only half of that in a control medium(Zarrouk). The biomass composition had a high carbohydrate content (37-44%),which suggests that A. platensis was stressed due to nutrient limitation. C. vulgaris grew well in PLL-based media and the biomass production was higher than in the control medium (BG-11). Biomass composition of C. vulgaris in PLL-basedmedia had lower protein content and higher carbohydrate and lipid content than in the control medium. The overall process for producing microalgal biomass fromPL thatwe propose includes: (i) acid extraction of nutrients through the generation of PL leachate (PLL), (ii) indoor PL composting and recovery of stripped ammonia and CO2, and (iii) use of recovered ammonia and CO2 along with the PLL for the cultivation of microalgae and cyanobacteria for the production of biomass. © 2015 Elsevier B.V. All rights reserved. Source


Argyri A.A.,Institute of Technology of Agricultural Products | Lyra E.,Institute of Technology of Agricultural Products | Panagou E.Z.,Agricultural University of Athens | Tassou C.C.,Institute of Technology of Agricultural Products
Food Microbiology | Year: 2013

The survival of Escherichia coli O157:H7, Salmonella Enteritidis and Listeria monocytogenes during the storage of fermented green table olives cv. Halkidiki in brine was studied in parallel with the evolution of lactic acid bacteria (LAB), yeasts and pH. The olives were previously fermented with a starter culture (a potential probiotic strain of Lactobacillus pentosus B281 - starter process) or with the indigenous microbiota (control). After the end of fermentation, olives were placed in brine, inoculated with a cocktail of 5 strains of E.coli O157:H7, 5 strains of L.monocytogenes and 4 strains of S. Enteritidis, with a final concentration in the brine of ca. 7.0 log CFU/ml, and subsequently packaged in polyethylene pouches and stored at 20°C. The population of E.coli O157:H7 reduced gradually and was detected in the brine until the 27th day of storage in both cases (i.e., starter and control process), and on olive fruits until the 19th and 16th days of storage in the starter and control process, respectively. S. Enteritidis population showed also a decrease and it was detected until the 21st day of storage in both brine and olive fruits in both cases. The population of L.monocytogenes declined during storage and it was detected until the 31st day of storage in both brine and olive fruits in both cases, showing a longer survival period in comparison to the other two studied pathogens. The presence of the potential probiotic starter did not affect the pathogen survival. The results demonstrated that even though the growth of the pathogenic strains was not supported, they may survive for a long period in a stressful environment of a fermented product with low pH value (4.2) and high salt concentration (6.0%). These results are a valuable contribution to risk assessment studies related to ready to eat foods in general. © 2013 Elsevier Ltd. Source


Blana V.A.,Agricultural University of Athens | Polymeneas N.,Agricultural University of Athens | Tassou C.C.,Institute of Technology of Agricultural Products | Panagou E.Z.,Agricultural University of Athens
Food Microbiology | Year: 2016

The survival of selected lactic acid bacteria (LAB) with in vitro probiotic potential was studied during storage of cv. Halkidiki green olives previously subjected to inoculated Spanish-style fermentation. After fermentation olives were packed in polyethylene pouches, covered with freshly prepared brine (9%, w/v, NaCl), acidified with 2‰ (w/v) citric acid and 1.5‰ (w/v) ascorbic acid, and stored at 4 and 20 °C for 357 days. Four packing treatments were studied, namely olives previously fermented by (i) the indigenous microbiota (control); (ii) Lactobacillus pentosus B281; (iii) Lactobacillus plantarum B282; and (iv) a co-culture of both LAB strains. Microbiological analyses were performed on the olives in parallel with physicochemical changes (pH, titratable acidity, salt content, aw and colour) at the early (day 1), middle (day 197) and final stage (day 357) of storage, as well as sensory evaluation at the end of the storage. The survival of probiotic strains was confirmed by Pulsed Field Gel Electrophoresis (PFGE). LAB decreased throughout storage reaching a final population of ca. 3.5-4.0 log CFU/g and 4.5-5.0 log CFU/g at 4 and 20 °C, respectively. The pH values ranged between 3.90 and 4.61 during storage depending on packaging condition. PFGE analysis revealed that L. pentosus B281 and L. plantarum B282 showed a high survival rate with a recovery of 100 and 96%, respectively, at 4 °C, and less than 20% for both strains at 20 °C. Finally, in the packing treatment with a co-culture of both strains, L. pentosus dominated over L. plantarum throughout storage at both temperatures. © 2015 Elsevier Ltd. Source


Blana V.A.,Agricultural University of Athens | Grounta A.,Agricultural University of Athens | Tassou C.C.,Institute of Technology of Agricultural Products | Nychas G.J.E.,Agricultural University of Athens | Panagou E.Z.,Agricultural University of Athens
Food Microbiology | Year: 2014

The performance of two strains of lactic acid bacteria (LAB), namely Lactobacillus pentosus B281 and Lactobacillus plantarum B282, previously isolated from industrially fermented table olives and screened invitro for probiotic potential, was investigated as starter cultures in Spanish style fermentation of cv. Halkidiki green olives. Fermentation was undertaken at room temperature in two different initial salt concentrations (8% and 10%, w/v, NaCl) in the brines. The strains were inoculated as single and combined cultures and the dynamics of their population on the surface of olives was monitored for a period of 114 days. The survival of inoculated strains on olives was determined using Pulsed Field Gel Electrophoresis (PFGE). Both probiotic strains successfully colonized the olive surface at populations ranged from 6.0 to 7.0logCFU/g throughout fermentation. PFGE analysis revealed that L.pentosus B281 presented higher colonization in both salt levels at the end of fermentation (81.2% and 93.3% in 8% and 10% NaCl brines, respectively). For L.plantarum B282 a high survival rate (83.3%) was observed in 8% NaCl brines, but in 10% NaCl the strain could not colonize the surface of olives. L.pentosus B281 also dominated over L.plantarum B282 in inoculated fermentations when the two strains were used as combined culture. The biochemical profile (pH, organic acids, volatile compounds) attained during fermentation and the sensory analysis of the final product indicated a typical lactic acid fermentation process of green olives. © 2013 Elsevier Ltd. Source


Argyri A.A.,Institute of Technology of Agricultural Products | Nisiotou A.A.,Institute of Technology of Agricultural Products | Mallouchos A.,Agricultural University of Athens | Panagou E.Z.,Agricultural University of Athens | Tassou C.C.,Institute of Technology of Agricultural Products
International Journal of Food Microbiology | Year: 2014

The performance of two potential probiotic Lactobacillus strains from olive microbiota, namely L. pentosus B281 and L. plantarum B282 was assessed as starter cultures in Spanish-style fermentation of heat shocked green olives cv. Halkidiki. Two different initial salt levels were studied, 10% (w/v) and 8% (w/v) NaCl, and the brines were inoculated with (a) L. pentosus B281, (b) L. plantarum B282, and (c) a mixture of both strains. A spontaneous fermentation was also taken into account as control treatment. Prior to brining, olives were heat shocked at 80. °C for 10. min to reduce the level of the indigenous microbiota on olive drupes and facilitate the dominance of the inoculated cultures. Microbiological, physicochemical and sensory analyses were conducted throughout fermentation. The composition of LAB population and the evolution of added inocula were assessed by Pulsed Field Gel Electrophoresis (PFGE). The final population of LAB was maintained above 6. log cycles in olive flesh. Both L. pentosus B281 and L. plantarum B282 were able to dominate over indigenous LAB, albeit strain B281 exhibited higher recovery percentages (100 or 94.7% for B281 and 58.8% or 55.0% for B282 in 10% or 8% NaCl, respectively). L. pentosus B281 also dominated over L. plantarum B282, when the two strains were co-inoculated in olive fermentations. The sensory assessment showed higher preference for inoculated fermentations of L. pentosus and L. plantarum separately in 8% NaCl, followed by the L. plantarum in 10% NaCl. The present study showed that probiotic strains L. pentosus B281 and L. plantarum B282, may offer a great potential for use as functional starter cultures in olive fermentation and deliver a promising probiotic food to the consumer. © 2013 Elsevier B.V. Source

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