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Papers by Madhuram Ravichandran

Research paper thumbnail of Preparation of Soy Protein Hydrolysates through alcalase treatment using Response Surface Methodology with Alzheimer's β‐amyloid (Aβ 1–42) Peptide Aggregation inhibition property

Research paper thumbnail of Electrostatic Sprays of Food-Grade Acids and Plant Extracts are More Effective than Conventional Sprays in Decontaminating Salmonella Typhimurium on Spinach

Journal of Food Science, 2010

About 40000 people fall victim to Salmonella infections every year in the United States. Recent o... more About 40000 people fall victim to Salmonella infections every year in the United States. Recent occurrences of Salmonella contaminated spinach and its recalls have accelerated the need for efficient antimicrobials targeting these pathogens. Our study was aimed at evaluating the inhibitory properties of malic, tartaric, and lactic acids, and grape seed extract (GSE) alone and in combinations and their application methods against Salmonella Typhimurium-inoculated spinach using a response surface method. Fresh spinach leaves were washed, disinfected with sodium hypochlorite solution (0.04% v/v), rewashed with sterile deionized (DI) water, and inoculated with a 2nd-day culture of S. Typhimurium (7.0 log CFU/mL). Adhered S. Typhimurium population on day 0 were 7.5 log CFU/g. These were treated with individual and combinations of organic acids with GSE or DI water (control) adjusted to the same pH as that of the test solutions with both the modes of application and leaves were refrigerated at 4 • C. Malic acid (2%) in combination with GSE (3%) or lactic acid (3%) sprayed electrostatically showed reductions of 2.6 to 3.3 log CFU/g compared to lower log reductions (0.0 to 0.3 log CFU/g) by day 14 if sprayed conventionally. These findings indicate that malic acid in combination with GSE/lactic acid solutions applied by electrostatic spraying exhibited higher inhibition of pathogens than conventional spraying and can be used for commercial applications to enhance food safety.

Research paper thumbnail of Enhancement of Antimicrobial Activities of Naturally Occurring Phenolic Compounds by Nanoscale Delivery Against Listeria Monocytogenes, Escherichia Coli O157:H7 and Salmonella Typhimurium in Broth and Chicken Meat System

Journal of Food Safety, 2011

Phenolic compounds commonly occurring in fruits, vegetables and tea were studied for their effect... more Phenolic compounds commonly occurring in fruits, vegetables and tea were studied for their effects on Listeria monocytogenes (L.m.), Escherichia coli O157:H7 (E.c.) and Salmonella Typhimurium (S.T.) in brain-heart infusion broth (BHI) and meat system. Incubated at 37C for 72 h in BHI, gentistic, benzoic and vanillic acids inhibited L.m., E.c and S.T. at 5,000 mg/mL by 2.8 to 3.0 log CFU/mL, 2.8 to 3.0 log CFU/mL and 2.7 to 2.9 log CFU/mL, respectively. Encapsulation of benzoic acid (1,100 mg/mL) in polylactic-co-glycolic acid nanoparticles inhibited 6.5 log CFU/mL of L.m. and S.T., and 6.0 log CFU/mL of E.c. at 48 h. In raw and cooked chicken meat systems, nanoparticle delivery of benzoic acid was effective against S.T. and L.m. (1.0 and 1.6 log CFU/g reduction of S.T. and 1.1 and 3.2 log CFU/g reduction of L.m. compared with 1.2 log CFU/g without nanoparticles on the days 9 and 14 of storage, respectively). These findings demonstrate the efficacy of phenolics on pathogen reduction delivered by nanoparticles and their potential for commercial food safety applications. PRACTICAL APPLICATIONS Nanotechnology is an emerging and promising technology that has been advocated for the delivery of antimicrobial phenolic compound extracts to effectively inhibit foodborne pathogens. The method improves the rate of inhibition compared with conventional delivery and retains the antimicrobial efficacy for a longer time. This hurdle technology using natural antimicrobials (phenolic compounds) and nanoparticle-mediated delivery system can effectively decontaminate foodborne pathogens and improve food safety. Phenolic compounds can be used as natural and safer alternatives to chemical disinfectants in food systems and delivered using nanoparticles to better control pathogens for commercial food safety applications. * Reduction in logs = (log number of controllog number of treatment) Ϯ standard error of mean. † The values with the same uppercase letters within a column were not statistically significant at P < 0.05; Log number at 0 h = 8.9 Ϯ 0.2 log CFU/mL. NANO-MEDIATED DELIVERY OF ANTIMICROBIALS * Reduction in logs = (Log number of control-Log number of treatment); Log number at 0 h in raw chicken were 5.9 Ϯ 0.1 log CFU/g of L.m. and 5.3 Ϯ 0.0 log CFU/g of S.T. Log number at 0 h in cooked chicken were 5.9 Ϯ 0.2 log CFU/g of L.m. and 5.3 Ϯ 0.1 log CFU/g of S.T. † There were no log reductions for the control (no treatment) samples. NANO-MEDIATED DELIVERY OF ANTIMICROBIALS

Research paper thumbnail of Enhancement of Antimicrobial Activity of Naturally occuring Phenolic Compounds by Nano-particle Mediated Delivery Against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium

II CHAPTER II LITERATURE REVIEW …………………………………………………………. A. United States meat industry and associ... more II CHAPTER II LITERATURE REVIEW …………………………………………………………. A. United States meat industry and associated outbreaks…………………………….. B. Methods of decontaminating raw and cooked poultry meat……………………….. C. Plant extracts ……………………...………………………………………………. D.

Research paper thumbnail of Biosorption of reactive dye using acid-treated rice husk: Factorial design analysis

Journal of Hazardous Materials, 2007

A factorial experimental design technique was used to investigate the biosorption of reactive red... more A factorial experimental design technique was used to investigate the biosorption of reactive red RGB (λ max = 521 nm) from water solution on rice husk treated with nitric acid. Biosorption is favored because of abundance of biomass, low cost, reduced sludge compared to conventional treatment techniques and better decontamination efficiency from highly diluted solutions. Factorial design of experiments is employed to study the effect of four factors pH (2 and 7), temperature (20 and 40), adsorbent dosage (5 and 50 mg/L) and initial concentration of the dye (50 and 250 mg/L) at two levels low and high. The efficiency of color removal was determined after 60 min of treatment. Main effects and interaction effects of the four factors were analyzed using statistical techniques. A regression model was suggested and it was found to fit the experimental data very well. The results were analyzed statistically using the Student's t-test, analysis of variance, F-test and lack of fit to define most important process variables affecting the percentage dye removal. The most significant variable was thus found to be pH.

Research paper thumbnail of Effects of process variables on kinetics of methylene blue sorption onto untreated guava (Psidium guajava) leaf powder: Statistical analysis

Chemical Engineering Journal, 2008

... Flasks were then kept in an incubated shaker and agitated at 200 rpm. ... [1] TG Chuah, A. Ju... more ... Flasks were then kept in an incubated shaker and agitated at 200 rpm. ... [1] TG Chuah, A. Jumasiah, I. Azni, S. Katayon and SY Thomas Choong, Rice husk as a potentially low-cost biosorbent for heavy metal and dye removal: an overview, Desalination 175 (2005), pp. 305–316. ...

Research paper thumbnail of Preparation of Soy Protein Hydrolysates through alcalase treatment using Response Surface Methodology with Alzheimer's β‐amyloid (Aβ 1–42) Peptide Aggregation inhibition property

Research paper thumbnail of Electrostatic Sprays of Food-Grade Acids and Plant Extracts are More Effective than Conventional Sprays in Decontaminating Salmonella Typhimurium on Spinach

Journal of Food Science, 2010

About 40000 people fall victim to Salmonella infections every year in the United States. Recent o... more About 40000 people fall victim to Salmonella infections every year in the United States. Recent occurrences of Salmonella contaminated spinach and its recalls have accelerated the need for efficient antimicrobials targeting these pathogens. Our study was aimed at evaluating the inhibitory properties of malic, tartaric, and lactic acids, and grape seed extract (GSE) alone and in combinations and their application methods against Salmonella Typhimurium-inoculated spinach using a response surface method. Fresh spinach leaves were washed, disinfected with sodium hypochlorite solution (0.04% v/v), rewashed with sterile deionized (DI) water, and inoculated with a 2nd-day culture of S. Typhimurium (7.0 log CFU/mL). Adhered S. Typhimurium population on day 0 were 7.5 log CFU/g. These were treated with individual and combinations of organic acids with GSE or DI water (control) adjusted to the same pH as that of the test solutions with both the modes of application and leaves were refrigerated at 4 • C. Malic acid (2%) in combination with GSE (3%) or lactic acid (3%) sprayed electrostatically showed reductions of 2.6 to 3.3 log CFU/g compared to lower log reductions (0.0 to 0.3 log CFU/g) by day 14 if sprayed conventionally. These findings indicate that malic acid in combination with GSE/lactic acid solutions applied by electrostatic spraying exhibited higher inhibition of pathogens than conventional spraying and can be used for commercial applications to enhance food safety.

Research paper thumbnail of Enhancement of Antimicrobial Activities of Naturally Occurring Phenolic Compounds by Nanoscale Delivery Against Listeria Monocytogenes, Escherichia Coli O157:H7 and Salmonella Typhimurium in Broth and Chicken Meat System

Journal of Food Safety, 2011

Phenolic compounds commonly occurring in fruits, vegetables and tea were studied for their effect... more Phenolic compounds commonly occurring in fruits, vegetables and tea were studied for their effects on Listeria monocytogenes (L.m.), Escherichia coli O157:H7 (E.c.) and Salmonella Typhimurium (S.T.) in brain-heart infusion broth (BHI) and meat system. Incubated at 37C for 72 h in BHI, gentistic, benzoic and vanillic acids inhibited L.m., E.c and S.T. at 5,000 mg/mL by 2.8 to 3.0 log CFU/mL, 2.8 to 3.0 log CFU/mL and 2.7 to 2.9 log CFU/mL, respectively. Encapsulation of benzoic acid (1,100 mg/mL) in polylactic-co-glycolic acid nanoparticles inhibited 6.5 log CFU/mL of L.m. and S.T., and 6.0 log CFU/mL of E.c. at 48 h. In raw and cooked chicken meat systems, nanoparticle delivery of benzoic acid was effective against S.T. and L.m. (1.0 and 1.6 log CFU/g reduction of S.T. and 1.1 and 3.2 log CFU/g reduction of L.m. compared with 1.2 log CFU/g without nanoparticles on the days 9 and 14 of storage, respectively). These findings demonstrate the efficacy of phenolics on pathogen reduction delivered by nanoparticles and their potential for commercial food safety applications. PRACTICAL APPLICATIONS Nanotechnology is an emerging and promising technology that has been advocated for the delivery of antimicrobial phenolic compound extracts to effectively inhibit foodborne pathogens. The method improves the rate of inhibition compared with conventional delivery and retains the antimicrobial efficacy for a longer time. This hurdle technology using natural antimicrobials (phenolic compounds) and nanoparticle-mediated delivery system can effectively decontaminate foodborne pathogens and improve food safety. Phenolic compounds can be used as natural and safer alternatives to chemical disinfectants in food systems and delivered using nanoparticles to better control pathogens for commercial food safety applications. * Reduction in logs = (log number of controllog number of treatment) Ϯ standard error of mean. † The values with the same uppercase letters within a column were not statistically significant at P < 0.05; Log number at 0 h = 8.9 Ϯ 0.2 log CFU/mL. NANO-MEDIATED DELIVERY OF ANTIMICROBIALS * Reduction in logs = (Log number of control-Log number of treatment); Log number at 0 h in raw chicken were 5.9 Ϯ 0.1 log CFU/g of L.m. and 5.3 Ϯ 0.0 log CFU/g of S.T. Log number at 0 h in cooked chicken were 5.9 Ϯ 0.2 log CFU/g of L.m. and 5.3 Ϯ 0.1 log CFU/g of S.T. † There were no log reductions for the control (no treatment) samples. NANO-MEDIATED DELIVERY OF ANTIMICROBIALS

Research paper thumbnail of Enhancement of Antimicrobial Activity of Naturally occuring Phenolic Compounds by Nano-particle Mediated Delivery Against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium

II CHAPTER II LITERATURE REVIEW …………………………………………………………. A. United States meat industry and associ... more II CHAPTER II LITERATURE REVIEW …………………………………………………………. A. United States meat industry and associated outbreaks…………………………….. B. Methods of decontaminating raw and cooked poultry meat……………………….. C. Plant extracts ……………………...………………………………………………. D.

Research paper thumbnail of Biosorption of reactive dye using acid-treated rice husk: Factorial design analysis

Journal of Hazardous Materials, 2007

A factorial experimental design technique was used to investigate the biosorption of reactive red... more A factorial experimental design technique was used to investigate the biosorption of reactive red RGB (λ max = 521 nm) from water solution on rice husk treated with nitric acid. Biosorption is favored because of abundance of biomass, low cost, reduced sludge compared to conventional treatment techniques and better decontamination efficiency from highly diluted solutions. Factorial design of experiments is employed to study the effect of four factors pH (2 and 7), temperature (20 and 40), adsorbent dosage (5 and 50 mg/L) and initial concentration of the dye (50 and 250 mg/L) at two levels low and high. The efficiency of color removal was determined after 60 min of treatment. Main effects and interaction effects of the four factors were analyzed using statistical techniques. A regression model was suggested and it was found to fit the experimental data very well. The results were analyzed statistically using the Student's t-test, analysis of variance, F-test and lack of fit to define most important process variables affecting the percentage dye removal. The most significant variable was thus found to be pH.

Research paper thumbnail of Effects of process variables on kinetics of methylene blue sorption onto untreated guava (Psidium guajava) leaf powder: Statistical analysis

Chemical Engineering Journal, 2008

... Flasks were then kept in an incubated shaker and agitated at 200 rpm. ... [1] TG Chuah, A. Ju... more ... Flasks were then kept in an incubated shaker and agitated at 200 rpm. ... [1] TG Chuah, A. Jumasiah, I. Azni, S. Katayon and SY Thomas Choong, Rice husk as a potentially low-cost biosorbent for heavy metal and dye removal: an overview, Desalination 175 (2005), pp. 305–316. ...