title: Modification of kraft wood-pulp fibre with silica for surface functionalisation

authors: Love, Karen T.

subjects: wood

abstract: A new science strategy for natural fibre modification was devised in which glass surface properties would be imparted to wood-derived fibre. The enhancements known from addition of silane reagents to glass fibre–polymer composites could therefore be realised for modified cellulose fibre–polymer composites. A process is described whereby the internal void spaces and micropores of never-dried Kraft pulp fibre walls were impregnated with silica. This was achieved by initial dehydration of never-dried fibre through azeotropic distillation to achieve substitution of fibre water with the silicon chemical solution over a range of concentrations. Kraft fibres were stiffened and made resistant to collapse from the effect of the azeotrope drying. Specific chemical reaction of azeotrope-dried fibre with the reagent ClSi(OEt)3 followed by base-catalysed hydrolysis of the ester groups formed a fibre-bound silica composite. The physico-chemical substitution of water from micropores and internal voids of never-dried fibre with property-modifying chemicals offers possibilities in the development of new fibre characteristics, including fibres which may be hardened, plasticised, and/or stabilised against moisture, biodegradation or fire. The embedded silica may also be used as sites of attachment for coupling agents to modify the hydrophilic character of the fibre or to functionalise the fibre surface.

text: Modification of kraft wood-pulp fibre with silica for surface functionalisation A new science strategy for natural fibre modification was devised in which glass surface properties would be imparted to wood-derived fibre. The enhancements known from addition of silane reagents to glass fibre–polymer composites could therefore be realised for modified cellulose fibre–polymer composites. A process is described whereby the internal void spaces and micropores of never-dried Kraft pulp fibre walls were impregnated with silica. This was achieved by initial dehydration of never-dried fibre through azeotropic distillation to achieve substitution of fibre water with the silicon chemical solution over a range of concentrations. Kraft fibres were stiffened and made resistant to collapse from the effect of the azeotrope drying. Specific chemical reaction of azeotrope-dried fibre with the reagent ClSi(OEt)3 followed by base-catalysed hydrolysis of the ester groups formed a fibre-bound silica composite. The physico-chemical substitution of water from micropores and internal voids of never-dried fibre with property-modifying chemicals offers possibilities in the development of new fibre characteristics, including fibres which may be hardened, plasticised, and/or stabilised against moisture, biodegradation or fire. The embedded silica may also be used as sites of attachment for coupling agents to modify the hydrophilic character of the fibre or to functionalise the fibre surface.

year: 2008

title: The Structure Of Hexa-O-acetyl-α-D-fructofuranose-β-d-fructofuranose 1,2':2,6'-Dianhydride

authors: Manley-Harris, Merilyn

subjects: Difructose dianhydride

abstract: The crystal structure of 3,4,6,1',3'4'-hexa-O-acetyl-α-D-fructofuranose-β-D-fructofuranose
1,2':2,6'-dianhydride, 1, has been determined. The central, eight-membered
1,3,6-trioxacane ring is in a twist-boat-chair conformation. Molecular modeling has
shown that this conformation is inherent and not due to crystal packing forces and is
also the most likely conformation present in underivatized α-D-fructofuranose-β-D-fructofuranose
1,2':2,6'-dianhydride.

text: The Structure Of Hexa-O-acetyl-α-D-fructofuranose-β-d-fructofuranose 1,2':2,6'-Dianhydride The crystal structure of 3,4,6,1',3'4'-hexa-O-acetyl-α-D-fructofuranose-β-D-fructofuranose
1,2':2,6'-dianhydride, 1, has been determined. The central, eight-membered
1,3,6-trioxacane ring is in a twist-boat-chair conformation. Molecular modeling has
shown that this conformation is inherent and not due to crystal packing forces and is
also the most likely conformation present in underivatized α-D-fructofuranose-β-D-fructofuranose
1,2':2,6'-dianhydride.

year: 2003-01-01

title: Microbiological quality of Toroi:  A Māori food delicacy

authors: Dixon, Lorraine Louise

subjects: Maori

abstract: A study was undertaken to determine the food safety of the fermented Māori delicacy, Toroi.  Ten batches of Toroi were prepared by a commonly used traditional method that consisted of boiling the vegetable component, either watercress or puha, and combining it with chopped mussel flesh.  The mixture was cooled and then stored in a refrigerator for up to eight months to allow natural fermentation to take place.  All ingredients were sourced from retail outlets.  The Toroi was examined at intervals over eight months for a range of pathogens (seven in all) that have been related to incidents of food poisoning in ready-to-eat foods in New Zealand.  The survival of a faecal contamination indicator, the laboratory grown strain Escherichia coli NZRM 916, was mapped over eight months.  Two strategies to prevent the growth of Listeria monocytogenes in Toroi were also investigated.  

Only one of the seven pathogens sought was recovered from any sample.  This pathogen was Bacillus cereus, a spore-former known to be associated with vegetables.  All batches contained B. cereus on the day of preparation but after two weeks refrigerated storage there was no further recovery from any sample.  There was a very low incidence of natural E. coli in the Toroi, consistent with levels permitted in mussels sold in retail outlets.  The laboratory grown strain, E. coli declined substantially over two months and was not recovered from any samples at eight months.  
A laboratory grown strain of Listeria monocytogenes, (L70) was added to Toroi and grew well with an increase in concentration of about seven-fold, over 19 days storage in a refrigerator.  A bacteriocin producing lactic acid bacterium, Lactobacillus sake Lb706, was added in combined culture with L. monocytogenes to Toroi.  It was found that at least 5 x108 L. sake cells were required as an inoculum to ensure elimination of L. monocytogenes from the Toroi.  When a purified bacteriocin; nisin, was added, a concentration of 10 mg g-1 in the Toroi was required to eliminate L. monocytogenes.  The inhibition study results suggest that unacceptably high inocula or purified bacteriocin would be required to prevent the growth of L. monocytogenes in Toroi.

The results of this suggest that Toroi be prepared from mussels either purchased from a retail outlet or harvested from sites known to be free from contamination.  Toroi should be safe to eat if prepared carefully, chilled promptly and thoroughly and allowed to ferment for at least two weeks.  In addition, care should be taken to maintain Toroi at refrigerated temperatures until it is eaten.

text: Microbiological quality of Toroi:  A Māori food delicacy A study was undertaken to determine the food safety of the fermented Māori delicacy, Toroi.  Ten batches of Toroi were prepared by a commonly used traditional method that consisted of boiling the vegetable component, either watercress or puha, and combining it with chopped mussel flesh.  The mixture was cooled and then stored in a refrigerator for up to eight months to allow natural fermentation to take place.  All ingredients were sourced from retail outlets.  The Toroi was examined at intervals over eight months for a range of pathogens (seven in all) that have been related to incidents of food poisoning in ready-to-eat foods in New Zealand.  The survival of a faecal contamination indicator, the laboratory grown strain Escherichia coli NZRM 916, was mapped over eight months.  Two strategies to prevent the growth of Listeria monocytogenes in Toroi were also investigated.  

Only one of the seven pathogens sought was recovered from any sample.  This pathogen was Bacillus cereus, a spore-former known to be associated with vegetables.  All batches contained B. cereus on the day of preparation but after two weeks refrigerated storage there was no further recovery from any sample.  There was a very low incidence of natural E. coli in the Toroi, consistent with levels permitted in mussels sold in retail outlets.  The laboratory grown strain, E. coli declined substantially over two months and was not recovered from any samples at eight months.  
A laboratory grown strain of Listeria monocytogenes, (L70) was added to Toroi and grew well with an increase in concentration of about seven-fold, over 19 days storage in a refrigerator.  A bacteriocin producing lactic acid bacterium, Lactobacillus sake Lb706, was added in combined culture with L. monocytogenes to Toroi.  It was found that at least 5 x108 L. sake cells were required as an inoculum to ensure elimination of L. monocytogenes from the Toroi.  When a purified bacteriocin; nisin, was added, a concentration of 10 mg g-1 in the Toroi was required to eliminate L. monocytogenes.  The inhibition study results suggest that unacceptably high inocula or purified bacteriocin would be required to prevent the growth of L. monocytogenes in Toroi.

The results of this suggest that Toroi be prepared from mussels either purchased from a retail outlet or harvested from sites known to be free from contamination.  Toroi should be safe to eat if prepared carefully, chilled promptly and thoroughly and allowed to ferment for at least two weeks.  In addition, care should be taken to maintain Toroi at refrigerated temperatures until it is eaten.

year: 2007