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Development of an eco-friendly agar extraction technique from the red seaweed Gracilaria lemaneiformis
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Abstracts / Journal of Biotechnology 131S (2007) S188–S195
extraction. On short times, the influence of the temperature was more noticeable than long extraction times. The conditions of temperature and time that produced the best yield of phenolic compound extraction from raspberry residues were of 60 ◦ C and 36 h with 37.7 g of total phenolic compounds extracted/100 g of dried sample, expressed like gallic acid equivalents and an EC 50 of 0.26 g extract/L, measured by the amount of extract necessary to cause 50% inhibition of the DPPH radical. References Cruz, J.M., Dom´ınguez, H., Paraj´o, J.C., 2004. Assessment of the production of antioxidants from winemaking waste solids. J. Agric. Food Chem. 52, 5612–5620. Wanasundara, U.N., Shahidi, F., 1998. Antioxidant and pro-oxidant activity of green tea extracts in marine oils. Food Chem. 63, 335–342.
doi:10.1016/j.jbiotec.2007.07.344 13. Non-reducing disaccharides for protection of lactic acid bacteria during lyophilisation and fluidised bed drying and subsequent storage Stephan Strasser ∗ , Markus Neureiter, Michaela Geppl, Rudolf Braun, Herbert Danner Department for Agrobiotechnology, Environ. Biotechnology, University of Natural Resources and Applied Life Sciences, Vienna, IFA-Tulln, Konrad Lorenz Str. 20A-3430 Tulln, Austria Introduction: In order to meet the requirements of product quality in terms of long-term stability, viability and activity of lactic acid bacteria starter cultures, the focus of the present study lies on the comparison of two different drying technologies, lyophilisation and fluidised bed drying. Enterococcus faecium and Lactobacillus plantarum were grown on a semi-industrial scale and harvested in early stationary phase after the end of acidifying activity. After separation the resulting bacterial suspension was incubated with 32% (w/v) of the protective carbohydrate additives glucose, trehalose, sucrose, or maltodextrin for 1 h at room temperature (Giulio et al., 2005). Subsequently the solutions were subjected to either freeze drying without further additives or to fluidised bed drying with powdered cellulose as inert carrier material. Samples of each experiment were stored at 4, 22, and 35 ◦ C and at certain intervals within half a year bacterial viability was determined by plate counting after 20 min of rehydration by submersion to examine storage stability. Results: In the presence of protective compounds freeze drying of E. faecium resulted in higher survival rates of up to 88% than fluidised bed drying maintaining a maximum of 70% viable cells of the initial population. In comparison, survival rates of untreated cells after freeze and fluidised bed drying decreased to 40 and 10%, respectively. The long-term stability of either dried samples decreased during storage, showing higher losses in viability at elevated storage temperatures. Storage at 35 ◦ C lead to a significant loss of bacterial viability after 1 month, especially of untreated and glucose treated cells. Sucrose turned out to be the most effective stabilising compound at this temper-
ature minimising the viability of freeze and fluidised bed dried cells after 4 months of storage for 30 and 20%, respectively. Sucrose and trehalose induced a greater protection for freeze and fluidised bed dried L. plantarum compared to maltodextrin and glucose. Untreated fluidised bed dried cells suffered severe damage losing three log cycles of the initial population. The reduction in viability observed during storage at 4 and 22 ◦ C was less in freeze dried than in fluidised bed dried cells, while neither of the protective additives exhibited a good preservative effect at 35 ◦ C storage temperature. Conclusion: L. plantarum is more sensitive to both drying methods than E. faecium which may be due to the higher surface area of lactobacillus cells and as a consequence increased membrane damage (Fonseca et al., 2000). Although survival rates vary between the strains, the non-reducing disaccharides trehalose and sucrose revealed best protection for both investigated lactic acid bacteria during processing and storage. The influence of protective additives appears to be species specific and therefore needs to be determined on a case-to-case basis. For industrial application it is necessary that a starter culture preserves high viability during the drying process and subsequent storage. In addition a process calculation needs to consider that fluidised bed drying consumes less time and energy than freeze drying and is a cost-effective alternative for preserving sensitive bioactive compounds. References Fonseca, F., B´eal, C., Corrieu, G., 2000. Method of quantifying the loss of acidification activity of lactic acid starters during freezing and frozen storage. J. Dairy Res. 67, 83–90. Giulio, B.D., Orlando, P., Barba, G., Coppola, R., Rosa, M.D., Sada, A., Prisco, P.P.D., Nazzaro, F., 2005. Use of alginate and cryo-protective sugars to improve the viability of lactic acid bacteria after freezing and freeze-drying. World J. Microbiol. Biotechnol. 21, 739–746.
doi:10.1016/j.jbiotec.2007.07.345 14. Development of an eco-friendly agar extraction technique from the red seaweed Gracilaria lemaneiformis Wei Zhang a,b,∗ , Haiyan Li a a
Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning Province, China b Department of Medical Biotechnology, School of Medicine, Flinders University, Room 5E110, Flinders Medical Centre, Bedford Park, 5042 Adelaide, SA, Australia Gracilaria species, being an efficient nutrient pump, offer both high bioremediation efficiency and have potential commercial value in established markets, such as agar production, human consumption, and fodder for other high-valued aquaculture organisms, such as abalone. It is one of the algal genera from which agar is extracted commercially and the main source of agar in the world. The current industrial practice uses sodium hypochlorite, hydrochloric acid and other chemicals as bleach-
Abstracts / Journal of Biotechnology 131S (2007) S188–S195
ing agents during the agar extracting process for a long time in China. The process produced different concentration of chloride gas, which is a high threat to the workers’ health. Furthermore, the after-effect of chloride gas and its effluents produced after bleaching pose a major threat to the environment. Considering the above-mentioned facts, an environmentally eco-friendly “green” bleaching agar extraction process is an urgent request. The red seaweed, Gracilaria lemaneiformis growing along the coasts of Liaodong Peninsula, China, was investigated for the agar production. An eco-friendly method called agar photobleaching extraction process was developed for the benefit of workers’ health and safety of the environment. The native agar (NA), alkali-modified agar (AA), chemical-bleached agar (CA) and photobleached agar (PA), which extracted using different processes, were evaluated for their physical and chemical properties. The PA had desirable performances in terms of gel strength, gelling temperature, sulfate content and 3,6-anhydro-
S195
l-galactose content. Among the different processed agars, PA gel strength was 1913 g/cm2 , the highest among the different processed agars, increased 8.6% on the base of the AA. Further we applied the new technique to extract agars from Gracilaria asiatica, and the results showed similarity with that of G. lemaneiformis. This indicates that the agar photobleaching extraction process is a feasible method for Gracilaria species and has a potential application. During the whole agar photobleaching extraction process the pigment content of G. lemaneiformis declined gradually and the TOC concentration in photobleaching solution increased along with the increase in the irradiation time. The mechanism of agar photobleaching could be elucidated by the photolysis theory. doi:10.1016/j.jbiotec.2007.07.346
Abstracts / Journal of Biotechnology 131S (2007) S188–S195
extraction. On short times, the influence of the temperature was more noticeable than long extraction times. The conditions of temperature and time that produced the best yield of phenolic compound extraction from raspberry residues were of 60 ◦ C and 36 h with 37.7 g of total phenolic compounds extracted/100 g of dried sample, expressed like gallic acid equivalents and an EC 50 of 0.26 g extract/L, measured by the amount of extract necessary to cause 50% inhibition of the DPPH radical. References Cruz, J.M., Dom´ınguez, H., Paraj´o, J.C., 2004. Assessment of the production of antioxidants from winemaking waste solids. J. Agric. Food Chem. 52, 5612–5620. Wanasundara, U.N., Shahidi, F., 1998. Antioxidant and pro-oxidant activity of green tea extracts in marine oils. Food Chem. 63, 335–342.
doi:10.1016/j.jbiotec.2007.07.344 13. Non-reducing disaccharides for protection of lactic acid bacteria during lyophilisation and fluidised bed drying and subsequent storage Stephan Strasser ∗ , Markus Neureiter, Michaela Geppl, Rudolf Braun, Herbert Danner Department for Agrobiotechnology, Environ. Biotechnology, University of Natural Resources and Applied Life Sciences, Vienna, IFA-Tulln, Konrad Lorenz Str. 20A-3430 Tulln, Austria Introduction: In order to meet the requirements of product quality in terms of long-term stability, viability and activity of lactic acid bacteria starter cultures, the focus of the present study lies on the comparison of two different drying technologies, lyophilisation and fluidised bed drying. Enterococcus faecium and Lactobacillus plantarum were grown on a semi-industrial scale and harvested in early stationary phase after the end of acidifying activity. After separation the resulting bacterial suspension was incubated with 32% (w/v) of the protective carbohydrate additives glucose, trehalose, sucrose, or maltodextrin for 1 h at room temperature (Giulio et al., 2005). Subsequently the solutions were subjected to either freeze drying without further additives or to fluidised bed drying with powdered cellulose as inert carrier material. Samples of each experiment were stored at 4, 22, and 35 ◦ C and at certain intervals within half a year bacterial viability was determined by plate counting after 20 min of rehydration by submersion to examine storage stability. Results: In the presence of protective compounds freeze drying of E. faecium resulted in higher survival rates of up to 88% than fluidised bed drying maintaining a maximum of 70% viable cells of the initial population. In comparison, survival rates of untreated cells after freeze and fluidised bed drying decreased to 40 and 10%, respectively. The long-term stability of either dried samples decreased during storage, showing higher losses in viability at elevated storage temperatures. Storage at 35 ◦ C lead to a significant loss of bacterial viability after 1 month, especially of untreated and glucose treated cells. Sucrose turned out to be the most effective stabilising compound at this temper-
ature minimising the viability of freeze and fluidised bed dried cells after 4 months of storage for 30 and 20%, respectively. Sucrose and trehalose induced a greater protection for freeze and fluidised bed dried L. plantarum compared to maltodextrin and glucose. Untreated fluidised bed dried cells suffered severe damage losing three log cycles of the initial population. The reduction in viability observed during storage at 4 and 22 ◦ C was less in freeze dried than in fluidised bed dried cells, while neither of the protective additives exhibited a good preservative effect at 35 ◦ C storage temperature. Conclusion: L. plantarum is more sensitive to both drying methods than E. faecium which may be due to the higher surface area of lactobacillus cells and as a consequence increased membrane damage (Fonseca et al., 2000). Although survival rates vary between the strains, the non-reducing disaccharides trehalose and sucrose revealed best protection for both investigated lactic acid bacteria during processing and storage. The influence of protective additives appears to be species specific and therefore needs to be determined on a case-to-case basis. For industrial application it is necessary that a starter culture preserves high viability during the drying process and subsequent storage. In addition a process calculation needs to consider that fluidised bed drying consumes less time and energy than freeze drying and is a cost-effective alternative for preserving sensitive bioactive compounds. References Fonseca, F., B´eal, C., Corrieu, G., 2000. Method of quantifying the loss of acidification activity of lactic acid starters during freezing and frozen storage. J. Dairy Res. 67, 83–90. Giulio, B.D., Orlando, P., Barba, G., Coppola, R., Rosa, M.D., Sada, A., Prisco, P.P.D., Nazzaro, F., 2005. Use of alginate and cryo-protective sugars to improve the viability of lactic acid bacteria after freezing and freeze-drying. World J. Microbiol. Biotechnol. 21, 739–746.
doi:10.1016/j.jbiotec.2007.07.345 14. Development of an eco-friendly agar extraction technique from the red seaweed Gracilaria lemaneiformis Wei Zhang a,b,∗ , Haiyan Li a a
Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning Province, China b Department of Medical Biotechnology, School of Medicine, Flinders University, Room 5E110, Flinders Medical Centre, Bedford Park, 5042 Adelaide, SA, Australia Gracilaria species, being an efficient nutrient pump, offer both high bioremediation efficiency and have potential commercial value in established markets, such as agar production, human consumption, and fodder for other high-valued aquaculture organisms, such as abalone. It is one of the algal genera from which agar is extracted commercially and the main source of agar in the world. The current industrial practice uses sodium hypochlorite, hydrochloric acid and other chemicals as bleach-
Abstracts / Journal of Biotechnology 131S (2007) S188–S195
ing agents during the agar extracting process for a long time in China. The process produced different concentration of chloride gas, which is a high threat to the workers’ health. Furthermore, the after-effect of chloride gas and its effluents produced after bleaching pose a major threat to the environment. Considering the above-mentioned facts, an environmentally eco-friendly “green” bleaching agar extraction process is an urgent request. The red seaweed, Gracilaria lemaneiformis growing along the coasts of Liaodong Peninsula, China, was investigated for the agar production. An eco-friendly method called agar photobleaching extraction process was developed for the benefit of workers’ health and safety of the environment. The native agar (NA), alkali-modified agar (AA), chemical-bleached agar (CA) and photobleached agar (PA), which extracted using different processes, were evaluated for their physical and chemical properties. The PA had desirable performances in terms of gel strength, gelling temperature, sulfate content and 3,6-anhydro-
S195
l-galactose content. Among the different processed agars, PA gel strength was 1913 g/cm2 , the highest among the different processed agars, increased 8.6% on the base of the AA. Further we applied the new technique to extract agars from Gracilaria asiatica, and the results showed similarity with that of G. lemaneiformis. This indicates that the agar photobleaching extraction process is a feasible method for Gracilaria species and has a potential application. During the whole agar photobleaching extraction process the pigment content of G. lemaneiformis declined gradually and the TOC concentration in photobleaching solution increased along with the increase in the irradiation time. The mechanism of agar photobleaching could be elucidated by the photolysis theory. doi:10.1016/j.jbiotec.2007.07.346