oscar ramos - Academia.edu (original) (raw)
Papers by oscar ramos
Critical Reviews in Food Science and Nutrition, 2015
Whey proteins are widely used as nutritional and functional ingredients in formulated foods becau... more Whey proteins are widely used as nutritional and functional ingredients in formulated foods because they are relative inexpensive, generally recognized as safe (GRAS) ingredient and possess important biological, physical and chemical functionalities. Denaturation and aggregation behavior of these proteins is of particular relevance toward manufacture of novel Downloaded by [89.155.140.137] at 16:41 11 June 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 nanostructures with a number of potential uses. When these processes are properly engineered and controlled, whey proteins may be formed into nanohydrogels, nanofibrils or nanotubes and be used as carrier of bioactive compounds. This review intends to discuss the latest understandings of nanoscale phenomena of whey protein denaturation and aggregation that may contribute for the design of protein nanostructures. Whey protein aggregation and gelation pathways under different processing and environmental conditions such as microwave heating, high voltage and moderate electrical fields, high pressure, temperature, pH and ionic strength were critically assessed. Moreover, several potential applications of nanohydrogels, nanofibrils and nanotubes for controlled release of nutraceutical compounds (e.g. probiotics, vitamins, antioxidants and peptides) were also included. Controlling the size of protein networks at nanoscale through application of different processing and environmental conditions can open perspectives for development of nanostructures with new or improved functionalities for incorporation and release of nutraceuticals in food matrices. Encapsulation Downloaded by [89.155.140.137] at 16:41 11 June 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT Downloaded by [89.155.140.137] at 16:41 11 June 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 4 2009; Chau et al. , 2007). Since nanostructures are submicron and sub-cellular in size, they have versatile advantages for targeted, site-specific delivery purposes as long as they may penetrate circulating systems and reach specific sites in the body . The properties of materials at this scale can be very different from conventional-sized materials manufactured from the same substance. This behavior is due to the large surface areato-volume ratio typically found in such nano-materials, but also to physical and chemical interactions between materials at the nanoscale that have a significant effect upon the overall properties of those systems . This nano-scale range can change or enhance properties, such as strength, reactivity and electrical characteristics, thus providing different or new functionality to existing productse.g. allow specific delivery and controlled release of nutraceuticals in food matrices, and improve adhesion to and absorption rates through cells .
Critical reviews in food science and nutrition, 2012
The latest decade has witnessed joint efforts by the packaging and the food industries to reduce ... more The latest decade has witnessed joint efforts by the packaging and the food industries to reduce the amount of residues and wastes associated with food consumption. The recent increase in environmental awareness has also contributed toward development of edible packaging materials. Viable edible films and coatings have been successfully produced from whey proteins; their ability to serve other functions, viz. carrier of antimicrobials, antioxidants, or other nutraceuticals, without significantly compromising the desirable primary barrier and mechanical properties as packaging films, will add value for eventual commercial applications. These points are tackled in this review, in a critical manner. The supply of whey protein-based films and coatings, formulated to specifically address end-user needs, is also considered.
Conventional and Advanced Food Processing Technologies, 2014
Food Research International, 2014
Production of edible nanostructures constitutes a major challenge in food nanotechnology, and has... more Production of edible nanostructures constitutes a major challenge in food nanotechnology, and has attracted a great deal of interest from several research fieldsincluding (but not limited to) food packaging. Furthermore, whey proteins are increasingly used as nutritional and functional ingredients owing to their important biological, physical and chemical functionalities. Besides their technological and functional characteristics, whey proteins are generally recognized as safe (GRAS). Denaturation and aggregation kinetics behavior of such proteins are of particular relevance toward manufacture of novel nanostructures possessing a number of potential uses. When these processes are properly engineered and controlled, whey proteins may form nanostructures useful as carriers of bioactive compounds (e.g. antimicrobials, antioxidants and nutraceuticals). This review discusses the latest advances in nano-scale phenomena involved in protein thermal aggregation aiming at formation of bio-based nano-coating networks. The extent of aggregation is dependent upon a balance between molecular interactions and environmental factors; therefore, the impact of these conditions is addressed in a critical manner. A particular emphasis is given to the effect of temperature as long as being one of the most critical variables. The application of moderate electric fields (MEF), an emergent approach, as such or combined with conventional heating is considered as it may inhibit/prevent excessive denaturation and aggregation of whey proteinsthus opening new perspectives for development of innovative protein nanostructures (i.e. nanocoatings). A better understanding of the mechanism(s) involved in whey protein denaturation and aggregation is crucial as it conveys information relevant to select methods for manipulating interactions between molecules, and thus control their functional properties in tailor-made applications in the food industry.
International Journal of Biological Macromolecules, 2012
The main objective of the present study was to evaluate the antibacterial effect -through the det... more The main objective of the present study was to evaluate the antibacterial effect -through the determination of minimum inhibitory (and lethal) concentrations, as well as the possible prebiotic potential of chitooligosaccharides (COS) -through the determination of growth curves, on Bifidobacterium animalis Bb12, Bifidobacterium animalis Bo and Lactobacillus acidophilus Ki. Atomic force microscopy was further used to obtain high resolution images of COS effects upon the cell morphology. Our results demonstrate that COS do not stimulate the growth of those strains, neither the strains are capable of using COS as a primary source of carbon. Analysis of morphology when exposed to inhibitory/bactericidal concentrations, suggested that COS do not exert any direct damage upon the bacteria structure, instead the bacteria are apparently covered by COS, which likely prevent nutrient uptake.
Food Research International, 2012
The goal of this research effort was to assess the efficacy of edible films produced from whey pr... more The goal of this research effort was to assess the efficacy of edible films produced from whey protein isolate (WPI) and glycerol, including incorporation of lactic acid (LA) and propionic acid (PRO), chitooligosaccharides with nominal MW of 3 kDa (COS) and natamycin (NA) as antimicrobial agents. Their features were evaluated in vitro via agar diffusion and viable cell counting, against spoilage microflora often found contaminating cheese surfaces. The effect of incorporating the aforementioned compounds upon thickness, moisture content (MC), solubility (S), density (ρ s ), water activity (a w ) and water vapor permeability (WVP), as well as upon tensile and optical properties of those films were also evaluated. Films formulated with LA, PRO or COS exhibited antimicrobial activity against all microorganisms tested, yet the viable cell count assay was more sensitive and reproducible. COS was the most active against Gram-negative bacteria, whereas LA was the most active against Gram-positive ones. NA was not active against bacteria, but displayed the strongest effect against yeasts. Incorporation of said antimicrobial compounds did not significantly (pN 0.05) affect film thickness, yet it significantly (p b 0.05) reduced tensile strength (TS). Incorporation of LA and NA in particular did not significantly (pb 0.05) affect MC, S, ρ s , WVP, elongation at break (EB) and Young's modulus (YM) values; however, a statistically significant increase (pb 0.05) of MC, S and WVP, together with a statistically significant decrease (p b 0.05) of ρ s were attained upon incorporation of PRO or COS. Moreover, PRO produced the highest variation (pb 0.05) in EB, TS and YM, whereas COS produced the highest change (pb 0.05) in optical properties.
Food Engineering Reviews, 2013
Nanotechnology has been referred to as one of the most interesting topics in food technology due ... more Nanotechnology has been referred to as one of the most interesting topics in food technology due to the potentialities of its use by food industry. This calls for studying the behavior of nanosystems as carriers of biological and functional compounds aiming at their utilization for delivery, controlled release and protection of such compounds during food processing and oral ingestion. This review highlights the principles of design and production of bio-nanosystems for oral delivery and their behavior within the human gastrointestinal (GI) tract, while providing an insight into the application of reverse engineering approach to the design of those bio-nanosystems. Nanocapsules, nanohydrogels, lipid-based and multilayer nanosystems are discussed (in terms of their main ingredients, production techniques, predominant forces and properties) and some examples of possible food applications are given. Phenomena occurring in in vitro digestion models are presented, mainly using examples related to the utilization of lipid-based nanosystems and their physicochemical behavior throughout the GI tract. Furthermore, it is shown how a reverse engineering approach, through two main steps, can be used to design bio-nanosystems for food applications, and finally a last section is presented to discuss future trends and consumer perception on food nanotechnology.
Critical Reviews in Food Science and Nutrition, 2012
Critical Reviews in Food Science and Nutrition, 2015
Whey proteins are widely used as nutritional and functional ingredients in formulated foods becau... more Whey proteins are widely used as nutritional and functional ingredients in formulated foods because they are relative inexpensive, generally recognized as safe (GRAS) ingredient and possess important biological, physical and chemical functionalities. Denaturation and aggregation behavior of these proteins is of particular relevance toward manufacture of novel Downloaded by [89.155.140.137] at 16:41 11 June 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 nanostructures with a number of potential uses. When these processes are properly engineered and controlled, whey proteins may be formed into nanohydrogels, nanofibrils or nanotubes and be used as carrier of bioactive compounds. This review intends to discuss the latest understandings of nanoscale phenomena of whey protein denaturation and aggregation that may contribute for the design of protein nanostructures. Whey protein aggregation and gelation pathways under different processing and environmental conditions such as microwave heating, high voltage and moderate electrical fields, high pressure, temperature, pH and ionic strength were critically assessed. Moreover, several potential applications of nanohydrogels, nanofibrils and nanotubes for controlled release of nutraceutical compounds (e.g. probiotics, vitamins, antioxidants and peptides) were also included. Controlling the size of protein networks at nanoscale through application of different processing and environmental conditions can open perspectives for development of nanostructures with new or improved functionalities for incorporation and release of nutraceuticals in food matrices. Encapsulation Downloaded by [89.155.140.137] at 16:41 11 June 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT Downloaded by [89.155.140.137] at 16:41 11 June 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 4 2009; Chau et al. , 2007). Since nanostructures are submicron and sub-cellular in size, they have versatile advantages for targeted, site-specific delivery purposes as long as they may penetrate circulating systems and reach specific sites in the body . The properties of materials at this scale can be very different from conventional-sized materials manufactured from the same substance. This behavior is due to the large surface areato-volume ratio typically found in such nano-materials, but also to physical and chemical interactions between materials at the nanoscale that have a significant effect upon the overall properties of those systems . This nano-scale range can change or enhance properties, such as strength, reactivity and electrical characteristics, thus providing different or new functionality to existing productse.g. allow specific delivery and controlled release of nutraceuticals in food matrices, and improve adhesion to and absorption rates through cells .
Critical reviews in food science and nutrition, 2012
The latest decade has witnessed joint efforts by the packaging and the food industries to reduce ... more The latest decade has witnessed joint efforts by the packaging and the food industries to reduce the amount of residues and wastes associated with food consumption. The recent increase in environmental awareness has also contributed toward development of edible packaging materials. Viable edible films and coatings have been successfully produced from whey proteins; their ability to serve other functions, viz. carrier of antimicrobials, antioxidants, or other nutraceuticals, without significantly compromising the desirable primary barrier and mechanical properties as packaging films, will add value for eventual commercial applications. These points are tackled in this review, in a critical manner. The supply of whey protein-based films and coatings, formulated to specifically address end-user needs, is also considered.
Conventional and Advanced Food Processing Technologies, 2014
Food Research International, 2014
Production of edible nanostructures constitutes a major challenge in food nanotechnology, and has... more Production of edible nanostructures constitutes a major challenge in food nanotechnology, and has attracted a great deal of interest from several research fieldsincluding (but not limited to) food packaging. Furthermore, whey proteins are increasingly used as nutritional and functional ingredients owing to their important biological, physical and chemical functionalities. Besides their technological and functional characteristics, whey proteins are generally recognized as safe (GRAS). Denaturation and aggregation kinetics behavior of such proteins are of particular relevance toward manufacture of novel nanostructures possessing a number of potential uses. When these processes are properly engineered and controlled, whey proteins may form nanostructures useful as carriers of bioactive compounds (e.g. antimicrobials, antioxidants and nutraceuticals). This review discusses the latest advances in nano-scale phenomena involved in protein thermal aggregation aiming at formation of bio-based nano-coating networks. The extent of aggregation is dependent upon a balance between molecular interactions and environmental factors; therefore, the impact of these conditions is addressed in a critical manner. A particular emphasis is given to the effect of temperature as long as being one of the most critical variables. The application of moderate electric fields (MEF), an emergent approach, as such or combined with conventional heating is considered as it may inhibit/prevent excessive denaturation and aggregation of whey proteinsthus opening new perspectives for development of innovative protein nanostructures (i.e. nanocoatings). A better understanding of the mechanism(s) involved in whey protein denaturation and aggregation is crucial as it conveys information relevant to select methods for manipulating interactions between molecules, and thus control their functional properties in tailor-made applications in the food industry.
International Journal of Biological Macromolecules, 2012
The main objective of the present study was to evaluate the antibacterial effect -through the det... more The main objective of the present study was to evaluate the antibacterial effect -through the determination of minimum inhibitory (and lethal) concentrations, as well as the possible prebiotic potential of chitooligosaccharides (COS) -through the determination of growth curves, on Bifidobacterium animalis Bb12, Bifidobacterium animalis Bo and Lactobacillus acidophilus Ki. Atomic force microscopy was further used to obtain high resolution images of COS effects upon the cell morphology. Our results demonstrate that COS do not stimulate the growth of those strains, neither the strains are capable of using COS as a primary source of carbon. Analysis of morphology when exposed to inhibitory/bactericidal concentrations, suggested that COS do not exert any direct damage upon the bacteria structure, instead the bacteria are apparently covered by COS, which likely prevent nutrient uptake.
Food Research International, 2012
The goal of this research effort was to assess the efficacy of edible films produced from whey pr... more The goal of this research effort was to assess the efficacy of edible films produced from whey protein isolate (WPI) and glycerol, including incorporation of lactic acid (LA) and propionic acid (PRO), chitooligosaccharides with nominal MW of 3 kDa (COS) and natamycin (NA) as antimicrobial agents. Their features were evaluated in vitro via agar diffusion and viable cell counting, against spoilage microflora often found contaminating cheese surfaces. The effect of incorporating the aforementioned compounds upon thickness, moisture content (MC), solubility (S), density (ρ s ), water activity (a w ) and water vapor permeability (WVP), as well as upon tensile and optical properties of those films were also evaluated. Films formulated with LA, PRO or COS exhibited antimicrobial activity against all microorganisms tested, yet the viable cell count assay was more sensitive and reproducible. COS was the most active against Gram-negative bacteria, whereas LA was the most active against Gram-positive ones. NA was not active against bacteria, but displayed the strongest effect against yeasts. Incorporation of said antimicrobial compounds did not significantly (pN 0.05) affect film thickness, yet it significantly (p b 0.05) reduced tensile strength (TS). Incorporation of LA and NA in particular did not significantly (pb 0.05) affect MC, S, ρ s , WVP, elongation at break (EB) and Young's modulus (YM) values; however, a statistically significant increase (pb 0.05) of MC, S and WVP, together with a statistically significant decrease (p b 0.05) of ρ s were attained upon incorporation of PRO or COS. Moreover, PRO produced the highest variation (pb 0.05) in EB, TS and YM, whereas COS produced the highest change (pb 0.05) in optical properties.
Food Engineering Reviews, 2013
Nanotechnology has been referred to as one of the most interesting topics in food technology due ... more Nanotechnology has been referred to as one of the most interesting topics in food technology due to the potentialities of its use by food industry. This calls for studying the behavior of nanosystems as carriers of biological and functional compounds aiming at their utilization for delivery, controlled release and protection of such compounds during food processing and oral ingestion. This review highlights the principles of design and production of bio-nanosystems for oral delivery and their behavior within the human gastrointestinal (GI) tract, while providing an insight into the application of reverse engineering approach to the design of those bio-nanosystems. Nanocapsules, nanohydrogels, lipid-based and multilayer nanosystems are discussed (in terms of their main ingredients, production techniques, predominant forces and properties) and some examples of possible food applications are given. Phenomena occurring in in vitro digestion models are presented, mainly using examples related to the utilization of lipid-based nanosystems and their physicochemical behavior throughout the GI tract. Furthermore, it is shown how a reverse engineering approach, through two main steps, can be used to design bio-nanosystems for food applications, and finally a last section is presented to discuss future trends and consumer perception on food nanotechnology.
Critical Reviews in Food Science and Nutrition, 2012