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Papers by Amos Nussinovitch
Microbial biotechnology, May 20, 2023
Soft rot pectobacteria (SRP) are phytopathogens of the genera Pectobacterium and Dickeya that cau... more Soft rot pectobacteria (SRP) are phytopathogens of the genera Pectobacterium and Dickeya that cause soft rots on a wide range of crops and ornamental plants. SRP produce plant cell wall degrading enzymes (PCWDEs), including pectinases. Bdellovibrio and like organisms are bacterial predators that can prey on a variety of Gram‐negative species, including SRP. In this research, a low methoxyl pectin (LMP)‐based immobilization system for B. bacteriovorus is established. It takes advantage that pectin residues induce PCWDE secretion by the pathogens, bringing upon the release of the encapsulated predators. Three commercial LMPs differing in the degree of esterification (DE) and amidation (DA) were tested as potential carriers, by examining their effect on SRP growth, enzymes secretion and substrate breakdown. A clear advantage was observed for pectin 5 CS with the lowest DE and DA content. The degradation of 5 CS pectin‐based carriers was further optimized by reducing cross‐linker and pectin concentration, by adding gelatin and by dehydration. This resulted in SRP‐induced disintegration of the carrier within 72 h. The released encapsulated predator caused a large decrease in SRP population while its own significantly increased, demonstrating the efficiency of this system in which the pathogen brings about its own demise.
Hydrocolloid Applications, 1997
Hydrocolloid Applications, 1997
Hydrocolloid Applications, 1997
Hydrocolloid Applications, 1997
Water-Soluble Polymer Applications in Foods
Hydrocolloid Applications, 1997
Hydrocolloids, 2000
Publisher Summary This chapter describes the experiments conducted to highlight the use of starch... more Publisher Summary This chapter describes the experiments conducted to highlight the use of starch as filler, matrix enhancer, and a carbon source in freeze-dried denitrifying alginate breads. In these experiments, freeze-dried, alginate-based beads used for the immobilization of a denitrifying bacterium (Pseudomonas sp.) were filled with different concentrations of granular starch. The beads were incubated under denitrifying conditions in laboratory-scale, flow-through columns and monitored for changes in their physical and denitrifying properties. Freeze-dried beads containing high concentrations of starch were found to have better mechanical and denitrifying properties than beads containing low concentrations of this filler. Nitrate removal by the beads was found to be correlated with the starch content of the beads. Nitrite accumulation, because of incomplete denitrification, increased with the decrease in starch content of the beads. Nitrite in the outlet of the columns was measured in all types of beads during the initial phase of incubation but was undetectable, with exception of beads with the lowest starch content, at later stages of incubation. The results showed that that it is possible to improve the mechanical properties of beads made of natural polymers by using similar methods to those applied in the field of synthetic polymers. Not only the mechanical properties but also the biological properties of the freeze-dried alginate beads were improved by using starch as both a filler and carbon source. Beads containing the highest concentration of starch (40%) revealed a superior performance with respect to both longevity and denitrification, as compared to beads with less starch.
More Cooking Innovations, 2018
Gums and Stabilisers for the Food Industry 12
RSC Publishing Logo. ...
Hydrocolloid Applications, 1997
International Journal of Pharmaceutics, 2010
The innate immunity utilizes a battery of broad-spectrum antibacterial cationic polypeptides name... more The innate immunity utilizes a battery of broad-spectrum antibacterial cationic polypeptides named defensins. In humans, defensins are the first line of defense against pathogens, and their expression has been implicated in several diseases. In addition to exerting direct antimicrobial effects, defensins facilitate and amplify innate and adaptive immune responses. HD-5 is a polypeptide that plays a pivotal role in combating bacteria in the digestive system. Our results show that HD-5 can be entrapped within alginate carriers and strengthen their structure without changing their brittleness. In addition, carrierentrapped HD-5 is released when incubated in buffer and/or stomach-simulating solution and still retains its activity after the release. This incubation also led to a decrease in carrier strength as well as an increase in their brittleness. Nevertheless the carriers did not disintegrate and remained intact throughout the diffusion process. The release of the defensin exhibited a bimodal behavior, suggesting that it was found both in a cross-linked and non-cross-linked form within the carrier. These results indicate that defensins encapsulated within alginate carriers could possibly be used for better mucosal immunity in the digestive system.
Journal of Adhesion Science and Technology, 1999
The adhesion of fertilized and nonfertilized Xenopus laevis eggs to various surfaces differing in... more The adhesion of fertilized and nonfertilized Xenopus laevis eggs to various surfaces differing in texture, roughness, and chemical composition was examined. Techniques regularly used in the fields of coating and adhesives were adopted. The stresses for the disconnection of eggs from different surfaces were evaluated by a custom-made apparatus, which disconnects the eggs by applying a regulated water pressure. The strength of adhesion depends, among others, on the roughness of the surfaces. A commercial roughness tester evaluated this parameter. It was observed that the rougher the surface, the better the adhesion between the egg and the surface. Maximal adhesion between the eggs and rough surfaces was detected 1 h after the first contact. For smooth surfaces (hydrogels), such a maximum was recognized only after 24 h had elapsed. In addition to the character of the surfaces, the creep of the jelly coat with time significantly influenced the strength of adhesion. The creep of the jelly coat was also depende...
International Journal of Food Science and Technology, 1997
A method of controlling the porosity of cellular solid foods and its dependence on solids content... more A method of controlling the porosity of cellular solid foods and its dependence on solids content were investigated. Freeze-dehydration of cold-set alginate gels was used to produce tailor-made porous solids. Gels were composed of sodium alginate, corn starch, oil and other additives necessary to induce gelation. Porosity values were derived from particle and bulk densities utilizing a helium pycnometer and a volumetric displacement method. To achieve a wider range of porosities, the gels were immersed in sucrose solutions of 10 to 60 ЊBx. Gel porosity after drying decreased from 0.85 to 0.42 and 0.07 after immersion in the 30 and 60 ЊBx solution for 183 and 158 h, respectively. Similarly, after immersing gels containing an additional 5% soy oil, porosity decreased to 0.36 and 0.04 after 165 and 158 h, in 30 and 60 ЊBx solution, respectively. Preparation and formulation play a significant role in porosity, and they can both be utilized to control its value within the range 0.85-0.04. SEM micrographs revealed changes in the original cellular solid, characterized by numerous large void spaces, to a denser and more uniform appearance of the specimen after immersion in the 60 ЊBx sucrose solution. The dry gel system with controlled porosity provides a novel tool for the production of tailor-made cellular-solid foods.
Microbial biotechnology, May 20, 2023
Soft rot pectobacteria (SRP) are phytopathogens of the genera Pectobacterium and Dickeya that cau... more Soft rot pectobacteria (SRP) are phytopathogens of the genera Pectobacterium and Dickeya that cause soft rots on a wide range of crops and ornamental plants. SRP produce plant cell wall degrading enzymes (PCWDEs), including pectinases. Bdellovibrio and like organisms are bacterial predators that can prey on a variety of Gram‐negative species, including SRP. In this research, a low methoxyl pectin (LMP)‐based immobilization system for B. bacteriovorus is established. It takes advantage that pectin residues induce PCWDE secretion by the pathogens, bringing upon the release of the encapsulated predators. Three commercial LMPs differing in the degree of esterification (DE) and amidation (DA) were tested as potential carriers, by examining their effect on SRP growth, enzymes secretion and substrate breakdown. A clear advantage was observed for pectin 5 CS with the lowest DE and DA content. The degradation of 5 CS pectin‐based carriers was further optimized by reducing cross‐linker and pectin concentration, by adding gelatin and by dehydration. This resulted in SRP‐induced disintegration of the carrier within 72 h. The released encapsulated predator caused a large decrease in SRP population while its own significantly increased, demonstrating the efficiency of this system in which the pathogen brings about its own demise.
Hydrocolloid Applications, 1997
Hydrocolloid Applications, 1997
Hydrocolloid Applications, 1997
Hydrocolloid Applications, 1997
Water-Soluble Polymer Applications in Foods
Hydrocolloid Applications, 1997
Hydrocolloids, 2000
Publisher Summary This chapter describes the experiments conducted to highlight the use of starch... more Publisher Summary This chapter describes the experiments conducted to highlight the use of starch as filler, matrix enhancer, and a carbon source in freeze-dried denitrifying alginate breads. In these experiments, freeze-dried, alginate-based beads used for the immobilization of a denitrifying bacterium (Pseudomonas sp.) were filled with different concentrations of granular starch. The beads were incubated under denitrifying conditions in laboratory-scale, flow-through columns and monitored for changes in their physical and denitrifying properties. Freeze-dried beads containing high concentrations of starch were found to have better mechanical and denitrifying properties than beads containing low concentrations of this filler. Nitrate removal by the beads was found to be correlated with the starch content of the beads. Nitrite accumulation, because of incomplete denitrification, increased with the decrease in starch content of the beads. Nitrite in the outlet of the columns was measured in all types of beads during the initial phase of incubation but was undetectable, with exception of beads with the lowest starch content, at later stages of incubation. The results showed that that it is possible to improve the mechanical properties of beads made of natural polymers by using similar methods to those applied in the field of synthetic polymers. Not only the mechanical properties but also the biological properties of the freeze-dried alginate beads were improved by using starch as both a filler and carbon source. Beads containing the highest concentration of starch (40%) revealed a superior performance with respect to both longevity and denitrification, as compared to beads with less starch.
More Cooking Innovations, 2018
Gums and Stabilisers for the Food Industry 12
RSC Publishing Logo. ...
Hydrocolloid Applications, 1997
International Journal of Pharmaceutics, 2010
The innate immunity utilizes a battery of broad-spectrum antibacterial cationic polypeptides name... more The innate immunity utilizes a battery of broad-spectrum antibacterial cationic polypeptides named defensins. In humans, defensins are the first line of defense against pathogens, and their expression has been implicated in several diseases. In addition to exerting direct antimicrobial effects, defensins facilitate and amplify innate and adaptive immune responses. HD-5 is a polypeptide that plays a pivotal role in combating bacteria in the digestive system. Our results show that HD-5 can be entrapped within alginate carriers and strengthen their structure without changing their brittleness. In addition, carrierentrapped HD-5 is released when incubated in buffer and/or stomach-simulating solution and still retains its activity after the release. This incubation also led to a decrease in carrier strength as well as an increase in their brittleness. Nevertheless the carriers did not disintegrate and remained intact throughout the diffusion process. The release of the defensin exhibited a bimodal behavior, suggesting that it was found both in a cross-linked and non-cross-linked form within the carrier. These results indicate that defensins encapsulated within alginate carriers could possibly be used for better mucosal immunity in the digestive system.
Journal of Adhesion Science and Technology, 1999
The adhesion of fertilized and nonfertilized Xenopus laevis eggs to various surfaces differing in... more The adhesion of fertilized and nonfertilized Xenopus laevis eggs to various surfaces differing in texture, roughness, and chemical composition was examined. Techniques regularly used in the fields of coating and adhesives were adopted. The stresses for the disconnection of eggs from different surfaces were evaluated by a custom-made apparatus, which disconnects the eggs by applying a regulated water pressure. The strength of adhesion depends, among others, on the roughness of the surfaces. A commercial roughness tester evaluated this parameter. It was observed that the rougher the surface, the better the adhesion between the egg and the surface. Maximal adhesion between the eggs and rough surfaces was detected 1 h after the first contact. For smooth surfaces (hydrogels), such a maximum was recognized only after 24 h had elapsed. In addition to the character of the surfaces, the creep of the jelly coat with time significantly influenced the strength of adhesion. The creep of the jelly coat was also depende...
International Journal of Food Science and Technology, 1997
A method of controlling the porosity of cellular solid foods and its dependence on solids content... more A method of controlling the porosity of cellular solid foods and its dependence on solids content were investigated. Freeze-dehydration of cold-set alginate gels was used to produce tailor-made porous solids. Gels were composed of sodium alginate, corn starch, oil and other additives necessary to induce gelation. Porosity values were derived from particle and bulk densities utilizing a helium pycnometer and a volumetric displacement method. To achieve a wider range of porosities, the gels were immersed in sucrose solutions of 10 to 60 ЊBx. Gel porosity after drying decreased from 0.85 to 0.42 and 0.07 after immersion in the 30 and 60 ЊBx solution for 183 and 158 h, respectively. Similarly, after immersing gels containing an additional 5% soy oil, porosity decreased to 0.36 and 0.04 after 165 and 158 h, in 30 and 60 ЊBx solution, respectively. Preparation and formulation play a significant role in porosity, and they can both be utilized to control its value within the range 0.85-0.04. SEM micrographs revealed changes in the original cellular solid, characterized by numerous large void spaces, to a denser and more uniform appearance of the specimen after immersion in the 60 ЊBx sucrose solution. The dry gel system with controlled porosity provides a novel tool for the production of tailor-made cellular-solid foods.