Background: Diarrhoea is the second leading cause of illness and death in developing countries an... more Background: Diarrhoea is the second leading cause of illness and death in developing countries and the second commonest cause of death due to infectious diseases among children under five in such countries. Parasites, as well as bacterial and viral pathogens, are important causes of diarrhoea. However, parasitic infections are sometimes overlooked, leading after a period of time to an uncertain aetiology. In this paper we report the prevalence of Giardia lamblia, Entamoeba histolytica and Cryptosporidium sp. in and around Kolkata. Findings: A hospital-based laboratory surveillance study was conducted among the patients admitted between November 2007 and October 2008 to the Infectious Diseases (ID) Hospital (Population = 1103) with diarrhoeal complaints. Of the 1103 samples collected, 147 were positive for Giardia lamblia, 84 for Cryptosporidium sp. and 51 for Entamoeba histolytica. For all these parasites there was a high rate of mixed infection with common enteric viruses and bacteria such as Rotavirus, Vibrio cholerae and Shigella sp. There were also cases of co-infection with all other diarrheogenic pathogens. The age group ≥ 5 years had the highest prevalence of parasites whereas the age group >5-10 years was predominantly infected with Giardia lamblia (p =< 0.001; Odds ratio (OR) = 3.937; 95% Confidence interval (CI) = 1.862-8.326) and with all parasites (p = 0.040; OR = 2.043; 95% CI = 1.033-4.039). The age group >10-20 years could also be considered at risk for G. lamblia (p = 0.009; OR = 2.231; 95% CI = 1.223-4.067). Month-wise occurrence data showed an endemic presence of G. lamblia whereas Cryptosporidium sp. and E. histolytica occurred sporadically. The GIS study revealed that parasites were more prevalent in areas such as Tangra, Tiljala and Rajarhat, which are mainly slum areas. Because most of the population surveyed was in the lower income group, consumption of contaminated water and food could be the major underlying cause of parasitic infestations. Conclusion: This study provides important information on the occurrence and distribution of three important intestinal parasites and indicates their diarrheogenic capacity in Kolkata and surrounding areas.
Worldwide, consumers demand for fresh and chemical free fresh fruits and vegetables are continuou... more Worldwide, consumers demand for fresh and chemical free fresh fruits and vegetables are continuously expanding, as these food items are rich in nutrition promoting good health and immunity. The primary challenge to cater to these increasing demands is the fact that fresh produce are perishable commodities, and need effective preservation strategies to successfully mitigate this challenge. Biopolymer based films and coatings have emerged as effective, biodegradable alternatives to their synthetic counterparts. Reinforcement of biopolymers with natural active agents such as essential oils and/or nanomaterials improves mechanical, thermal, barrier, and functional (antimicrobial and antioxidant) properties of these composite films and coatings. Numerous published reports have demonstrated that biopolymer-based films and coatings can effectively reduce weight loss, and postharvest decay such as biochemical and microbial spoilage of coated fresh fruits and vegetables resulting in their po...
Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farm... more Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farmers in Minnesota were conducted to determine the coliform count and the prevalence of Escherichia coli, Salmonella, and E. coli O157:H7. A total of 476 and 129 produce samples were collected from 32 organic and 8 conventional farms, respectively. The samples included tomatoes, leafy greens, lettuce, green peppers, cabbage, cucumbers, broccoli, strawberries, apples, and seven other types of produce. The numbers of fruits and vegetables was in uenced by their availability at participating farms and varied from 11 strawberry samples to 108 tomato samples. Among the organic farms, eight were certi ed by accredited agencies and the rest reported the use of organic practices. All organic farms used aged or composted animal manure as fertilizer. The average coliform counts in both organic and conventional produce were 2.9 log most probable number per g. The percentages of E. coli–positive sam...
Microbiological analyses of fruits and vegetables produced by farms in Minnesota and Wisconsin we... more Microbiological analyses of fruits and vegetables produced by farms in Minnesota and Wisconsin were conducted to determine the prevalence of Escherichia coli in pre-harvest fruits and vegetables. During the 2003 and 2004 harvest seasons, 14 organic (certified by accredited organic agencies), 30 semi-organic (used organic practices but not certified) and 19 conventional farms were sampled to analyze 2029 pre-harvest produce samples (473 organic, 911 semi-organic, 645 conventional). Before each harvest season, a farmer survey was conducted to collect relevant information on farm management practices that might affect the risk of E. coli contamination in fresh produce. The use of animal wastes for fertilization of produce plants increased the risk of E. coli contamination in organic (OR=13.2, 95% CI=2.2-61.2, P-value<0.0001) and semi-organic (OR=12.9, 95% CI=2.9-56.3, P-value<0.0001) produce significantly. Improper ageing of untreated animal manure significantly increased this ri...
Rapid postharvest losses and quality deteriorations in pineapple are major challenges to growers ... more Rapid postharvest losses and quality deteriorations in pineapple are major challenges to growers and handlers. Chitosan-based coatings on fruit surfaces have gained importance in recent years to enhance postharvest shelf life of the fruits. In this study, aloe vera gel was added as a natural antioxidant in chitosan-based composite coating containing ZnO nanoparticles. The developed formulation was applied on the surface of freshly harvested pineapple fruits. ZnO nanoparticles were used as an antimicrobial agent. Coated pineapple fruits were evaluated for weight loss, total soluble solids, titratable acidity, decay index, maturity index, and sensory attributes, including visual appearance, periodically at 5 day interval during storage. The results showed that the coating of the fruit reduced weight loss by about 5%, and also delayed ripening and oxidative decay compared to the uncoated fruit. Thus, the developed coating formulation is a promising sustainable solution to reduce postha...
Consumers increasingly prefer healthy and nutritious diet worldwide, and demands for fresh fruits... more Consumers increasingly prefer healthy and nutritious diet worldwide, and demands for fresh fruits and vegetables are rapidly growing. Fresh produce are perishable commodities, and physical damage, moisture loss, biochemical changes, and postharvest microbial decay are primary causes of quality loss and reduced shelf-life. Packaging, including plastic films and coatings is an effective strategy to improve postharvest-life of whole and cut fruits and vegetables. However, plastic packaging is a significant environmental concern globally. Biopolymer based films and/or coatings are environment-friendly alternative packaging for food. But, these biopolymers, derived from plant, animal and microbial sources, lack some of the primary physico-chemical and mechanical properties compared to conventional plastic packaging. Reinforcement of biopolymer with nanomaterials addresses these shortcomings, and adds functional properties such as antimicrobial and/or antioxidant activities to the nanocomposites. Organic (e.g. nanocellulose fibrils), and inorganic (e.g. montmorillonite, zinc oxide, silver) nanomaterials are effective in achieving these improvements in biopolymer based nanocomposite. Plant-extracts and compounds derived from plant (e.g. essential oil) are also effective in imparting antimicrobial and antioxidant properties to biopolymer based nanocomposites. This is an extensive review of research works on effectiveness of biopolymer based nanocomposite films and coatings used for packaging of whole and cut fruits and vegetables to extend their shelf-life. Numerous reports have demonstrated effectiveness of biopolymer based nanocomposites in improvement in shelf-life of packaged and/or coated whole and cut fruits and vegetables by at least 4-5 days to as much as a few months. Highlights Fresh produce are perishable commodities requiring package or coating. Conventional plastics and waxes are major environmental and health concerns. Biopolymer based nanocomposites are environment-friendly alternatives. These nanocomposite films and coatings are effective in enhancing shelf-life.
Zinc oxide nanoparticles (ZnONPs) were synthesized by green protocol using Mimusops elengi fruit ... more Zinc oxide nanoparticles (ZnONPs) were synthesized by green protocol using Mimusops elengi fruit extract as a novel natural resource. The synthesized particles were polyhedral (mostly hexagonal) in shape between 14 - 48 nm with an average size of 24.75 ± 0.78 nm. Nano zinc oxide (ZnO) at concentrations of 2% (w/w) and 4% (w/w), were incorporated into agar matrix. Solution casting method was used to fabricate the bionanocomposite films with ZnONPs in agar. Surface morphology, particle size, crystallinity, thermal stability and functional groups were determined using SEM, TEM, XRD, TGA and FTIR, respectively. Loading of ZnONPs in composite films improved thermal stability, elongation and film thickness, whereas tensile strength and transparency decreased. The films were used for packaging of green grapes, and appearance of the fruit was observed during ambient storage. Grapes packaged in composite films showed fresh appearance up to 14 and 21 days in ambient conditions for 2% (w/w) and 4% (w/w) ZnONPs in films, respectively. The results showed the potential of the fabricated agar-ZnO nanocomposite film as a promising packaging material to enhance postharvest shelf-life of fresh fruits like green grapes.
Internalization of Escherichia coli O157:H7 in nonintact beef products during mechanical tenderiz... more Internalization of Escherichia coli O157:H7 in nonintact beef products during mechanical tenderization or during injection of marination and tenderization ingredients is of concern if such products are undercooked. This study tested organic acids (0.2% citric acid and 0.3% acetic acid), potassium and calcium salts (1.8% potassium lactate, 0.63% calcium lactate, 0.86% calcium ascorbate, and 0.23% calcium chloride), and sodium chloride (2.5%) for their influence on thermal destruction of E. coli O157:H7 in ground beef serving as a model system. Ground beef batches (700 g; 5% fat) were mixed with equal volumes (22 ml) of each treatment solution or distilled water and portions (30 g) of treated ground beef were extruded in test tubes (2.5 by 10 cm). A five-strain mixture of E. coli O157:H7 (0.3 ml; 7 log CFU/g) was introduced at the center of the sample with a pipette. After overnight storage (4 degrees C), simulating product marination, samples were heated to 60 or 65 degrees C internal temperature, simulating rare and medium rare doneness of beef, in a circulating water bath. At 65 degrees C, treatments with citric and acetic acid showed greater (P < 0.05) reduction (4 to 5 log CFU/g) of E. coli O157:H7 than all the other ingredients and the control (3 to 4 log CFU/g). Sodium chloride reduced weight losses (16 to 18% compared with 20 to 27% by citric or acetic acid) and resulted in a 4-log reduction in counts during cooking to 65 degrees C. Ingredients such as citric or acetic acid may improve thermal inactivation of E. coli O157:H7 internalized in nonintact beef products, while sodium chloride may reduce cooking losses in such products.
International journal of clinical and experimental medicine, 2015
A green method of Silver nanoparticles (AgNPs) preparation has been established. This method depe... more A green method of Silver nanoparticles (AgNPs) preparation has been established. This method depends on reduction of silver nitrate with soluble starch. The formation of AgNPs was observed by the color change from colorless to dark brown through the starch addition into silver nitrate solution. It was observed that use of starch makes convenient method for the synthesis of silver nanoparticles and can reduce silver ions into the produced silver nanoparticles within one hour of reaction time without using any harsh conditions. The prepared silver nanoparticles were characterized by using UV-visible spectroscopy and evaluated for its antimicrobial activity. The synthesized green AgNPs showed a potential antibacterial activity that was stronger against Gram positive pathogenic bacteria (Staphylococus aureus and Streptococus pyogenes) than against Gram negative pathogenic bacteria (Salmonella typhi, Shigellasonnei and Pseudomonas aeruginosa). Inhibition zones diameter of antibacterial a...
Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farm... more Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farmers in Minnesota were conducted to determine the coliform count and the prevalence of Escherichia coli, Salmonella, and E. coli O157:H7. A total of 476 and 129 produce samples were collected from 32 organic and 8 conventional farms, respectively. The samples included tomatoes, leafy greens, lettuce, green peppers, cabbage, cucumbers, broccoli, strawberries, apples, and seven other types of produce. The numbers of fruits and vegetables was influenced by their availability at participating farms and varied from 11 strawberry samples to 108 tomato samples. Among the organic farms, eight were certified by accredited agencies and the rest reported the use of organic practices. All organic farms used aged or composted animal manure as fertilizer. The average coliform counts in both organic and conventional produce were 2.9 log most probable number per g. The percentages of E. coli-positive sam...
Microbiological analyses of fruits and vegetables produced by farms in Minnesota and Wisconsin we... more Microbiological analyses of fruits and vegetables produced by farms in Minnesota and Wisconsin were conducted to determine coliform and Escherichia coli counts and the prevalence of E. coli, Salmonella, and E. coli O157:H7. During the 2003 and 2004 harvest seasons, 14 organic farms (certified by accredited organic agencies), 30 semiorganic farms (used organic practices but not certified), and 19 conventional farms were sampled to analyze 2,029 preharvest produce samples (473 organic, 911 semiorganic, and 645 conventional). Produce varieties included mainly lettuces, leafy greens, cabbages, broccoli, peppers, tomatoes, zucchini, summer squash, cucumber, and berries. Semiorganic and organic farms provided the majority of leafy greens and lettuces. Produce samples from the three farm types had average coliform counts of 1.5 to 2.4 log most probable number per g. Conventional produce had either significantly lower or similar coliform populations compared with the semiorganic and organic...
The demand for fresh fruits and vegetables as popular food choices in our daily diet has been inc... more The demand for fresh fruits and vegetables as popular food choices in our daily diet has been increasing in recent years. As consumers are becoming increasingly aware of the potential health benefits, they are consuming more fresh produce in their diets. The market for fresh ...
This study evaluated chemical tenderizers and cooking methods to inactivate Escherichia coli O157... more This study evaluated chemical tenderizers and cooking methods to inactivate Escherichia coli O157:H7 in ground beef patties (model system for non-intact beef). Ground beef was inoculated with E. coli O157:H7 and mixed with (i) nothing (control), (ii) calcium chloride (CC) and flavoring agents (FA), (iii) CC, FA, and acetic acid (AA), (iv) sodium chloride (SC), sodium tripolyphosphate (ST), and potassium lactate (PL), and (v) the combination of SC, ST, PL, and AA. Patties were stored in aerobic or vacuum bags at − 20, 4, and 12°C. Samples were grilled, broiled, or pan-fried to 60 or 65°C. Total bacterial and E. coli O157:H7 populations remained unchanged during storage. Broiling was more effective in reducing E. coli O157:H7 than grilling and pan-frying, and acidified tenderizers reduced E. coli O157:H7 more than non-acidified tenderizers in broiling. Higher reductions were observed at 65°C than 60°C in broiled and grilled samples. These results indicate that acidified tenderizers and broiling may be useful in non-intact beef safety.
This study evaluated the effects of meat binding or restructuring formulations, including salt/ph... more This study evaluated the effects of meat binding or restructuring formulations, including salt/phosphate, algin/calcium, Activa TM RM, and Fibrimex R , with or without 0.27% (wt/wt) lactic acid, on thermal inactivation of internalized Escherichia coli O157:H7 in ground beef, serving as a model system for restructured products. Ground beef batches (700 g; approximately 5% fat) were mechanically mixed with a 5-strain composite of E. coli O157:H7 (7 log CFU/g) and then with the restructuring formulations. Product portions (30 g) were extruded into plastic test tubes (2.5 × 10 cm) and stored at 4 • C (18 h), before heating to 60 or 65 • C in a circulating water bath to simulate rare or medium-rare doneness of beef, respectively. Cooking to 60 or 65 • C reduced (P < 0.05) bacterial counts of control samples by 1.8 and 3.2 log CFU/g, respectively. Thermal destruction at 60 • C was not different (P > 0.05) among all treatments and the control. At 65 • C, greater (P < 0.05) thermal inactivation of E. coli O157:H7, as compared to the control, was obtained in samples treated with lactic acid alone (reductions of 4.9 log CFU/g), whereas for all other treatments, microbial destruction (reductions of 2.2 to 4.5 log CFU/g) was comparable (P > 0.05) to that of the control. Cooking weight losses were lower (P < 0.05) in salt/phosphate samples (<1%) compared to other formulations and the control (7.4% to 15.9%). Findings indicated that, under the conditions examined, restructuring of beef with salt/phosphate, algin/calcium, Activa TM RM, or Fibrimex R did not affect inactivation of internalized E. coli O157:H7 in undercooked (60 or 65 • C) samples, whereas inclusion of lactic acid (0.27%) in nonintact beef products enhanced pathogen destruction at 65 • C.
Escherichia coli O157:H7 is a pathogenic bacterium that causes enterohaemorrhagic infections. Acc... more Escherichia coli O157:H7 is a pathogenic bacterium that causes enterohaemorrhagic infections. According to the Centers for Disease Control and Prevention, this organism is responsible for more than 73 000 human cases every year in the United States, and the majority of those infections are sporadic cases (Mead et al. 1999). In recent years, however, there has been a decline in the incidence of E. coli O157:H7 (CDC 2005). Infections caused by E. coli O157:H7 are typically associated with the consumption of contaminated foods, but approximately half of all outbreaks are transmitted by other routes such as water and person to person (Rangel et al. 2005). Because cattle are a primary natural reservoir, the risk factors identified for sporadic cases include consumption of poorly cooked ground beef, visiting and living on a farm, living in agricultural areas, contact with farm animals and contact with cattle manure (Michel et al. 1999; Kassenborg et al. 2004). Cattle and sheep manure can serve as the vehicle for E. coli O157:H7 contamination of fruits, vegetables, water and soil (Hilborn et al. 1999; Chalmers et al. 2000; Rangel et al. 2005). This pathogen can also be transmitted directly from manure; this infection route has been implicated in several outbreaks (Duffy 2003). In 2000, 20
... Thermal Inactivation of Escherichia coli O157:H7 in Beef Treated with Marination and Tenderiz... more ... Thermal Inactivation of Escherichia coli O157:H7 in Beef Treated with Marination and Tenderization Ingredients AVIK MUKHERJEE, YOHAN YOON, KEITH E. BELK, JOHN A. SCANGA, GARY C. SMITH, AND JOHN N. SOFOS* ...
Background: Diarrhoea is the second leading cause of illness and death in developing countries an... more Background: Diarrhoea is the second leading cause of illness and death in developing countries and the second commonest cause of death due to infectious diseases among children under five in such countries. Parasites, as well as bacterial and viral pathogens, are important causes of diarrhoea. However, parasitic infections are sometimes overlooked, leading after a period of time to an uncertain aetiology. In this paper we report the prevalence of Giardia lamblia, Entamoeba histolytica and Cryptosporidium sp. in and around Kolkata. Findings: A hospital-based laboratory surveillance study was conducted among the patients admitted between November 2007 and October 2008 to the Infectious Diseases (ID) Hospital (Population = 1103) with diarrhoeal complaints. Of the 1103 samples collected, 147 were positive for Giardia lamblia, 84 for Cryptosporidium sp. and 51 for Entamoeba histolytica. For all these parasites there was a high rate of mixed infection with common enteric viruses and bacteria such as Rotavirus, Vibrio cholerae and Shigella sp. There were also cases of co-infection with all other diarrheogenic pathogens. The age group ≥ 5 years had the highest prevalence of parasites whereas the age group >5-10 years was predominantly infected with Giardia lamblia (p =< 0.001; Odds ratio (OR) = 3.937; 95% Confidence interval (CI) = 1.862-8.326) and with all parasites (p = 0.040; OR = 2.043; 95% CI = 1.033-4.039). The age group >10-20 years could also be considered at risk for G. lamblia (p = 0.009; OR = 2.231; 95% CI = 1.223-4.067). Month-wise occurrence data showed an endemic presence of G. lamblia whereas Cryptosporidium sp. and E. histolytica occurred sporadically. The GIS study revealed that parasites were more prevalent in areas such as Tangra, Tiljala and Rajarhat, which are mainly slum areas. Because most of the population surveyed was in the lower income group, consumption of contaminated water and food could be the major underlying cause of parasitic infestations. Conclusion: This study provides important information on the occurrence and distribution of three important intestinal parasites and indicates their diarrheogenic capacity in Kolkata and surrounding areas.
Worldwide, consumers demand for fresh and chemical free fresh fruits and vegetables are continuou... more Worldwide, consumers demand for fresh and chemical free fresh fruits and vegetables are continuously expanding, as these food items are rich in nutrition promoting good health and immunity. The primary challenge to cater to these increasing demands is the fact that fresh produce are perishable commodities, and need effective preservation strategies to successfully mitigate this challenge. Biopolymer based films and coatings have emerged as effective, biodegradable alternatives to their synthetic counterparts. Reinforcement of biopolymers with natural active agents such as essential oils and/or nanomaterials improves mechanical, thermal, barrier, and functional (antimicrobial and antioxidant) properties of these composite films and coatings. Numerous published reports have demonstrated that biopolymer-based films and coatings can effectively reduce weight loss, and postharvest decay such as biochemical and microbial spoilage of coated fresh fruits and vegetables resulting in their po...
Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farm... more Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farmers in Minnesota were conducted to determine the coliform count and the prevalence of Escherichia coli, Salmonella, and E. coli O157:H7. A total of 476 and 129 produce samples were collected from 32 organic and 8 conventional farms, respectively. The samples included tomatoes, leafy greens, lettuce, green peppers, cabbage, cucumbers, broccoli, strawberries, apples, and seven other types of produce. The numbers of fruits and vegetables was in uenced by their availability at participating farms and varied from 11 strawberry samples to 108 tomato samples. Among the organic farms, eight were certi ed by accredited agencies and the rest reported the use of organic practices. All organic farms used aged or composted animal manure as fertilizer. The average coliform counts in both organic and conventional produce were 2.9 log most probable number per g. The percentages of E. coli–positive sam...
Microbiological analyses of fruits and vegetables produced by farms in Minnesota and Wisconsin we... more Microbiological analyses of fruits and vegetables produced by farms in Minnesota and Wisconsin were conducted to determine the prevalence of Escherichia coli in pre-harvest fruits and vegetables. During the 2003 and 2004 harvest seasons, 14 organic (certified by accredited organic agencies), 30 semi-organic (used organic practices but not certified) and 19 conventional farms were sampled to analyze 2029 pre-harvest produce samples (473 organic, 911 semi-organic, 645 conventional). Before each harvest season, a farmer survey was conducted to collect relevant information on farm management practices that might affect the risk of E. coli contamination in fresh produce. The use of animal wastes for fertilization of produce plants increased the risk of E. coli contamination in organic (OR=13.2, 95% CI=2.2-61.2, P-value<0.0001) and semi-organic (OR=12.9, 95% CI=2.9-56.3, P-value<0.0001) produce significantly. Improper ageing of untreated animal manure significantly increased this ri...
Rapid postharvest losses and quality deteriorations in pineapple are major challenges to growers ... more Rapid postharvest losses and quality deteriorations in pineapple are major challenges to growers and handlers. Chitosan-based coatings on fruit surfaces have gained importance in recent years to enhance postharvest shelf life of the fruits. In this study, aloe vera gel was added as a natural antioxidant in chitosan-based composite coating containing ZnO nanoparticles. The developed formulation was applied on the surface of freshly harvested pineapple fruits. ZnO nanoparticles were used as an antimicrobial agent. Coated pineapple fruits were evaluated for weight loss, total soluble solids, titratable acidity, decay index, maturity index, and sensory attributes, including visual appearance, periodically at 5 day interval during storage. The results showed that the coating of the fruit reduced weight loss by about 5%, and also delayed ripening and oxidative decay compared to the uncoated fruit. Thus, the developed coating formulation is a promising sustainable solution to reduce postha...
Consumers increasingly prefer healthy and nutritious diet worldwide, and demands for fresh fruits... more Consumers increasingly prefer healthy and nutritious diet worldwide, and demands for fresh fruits and vegetables are rapidly growing. Fresh produce are perishable commodities, and physical damage, moisture loss, biochemical changes, and postharvest microbial decay are primary causes of quality loss and reduced shelf-life. Packaging, including plastic films and coatings is an effective strategy to improve postharvest-life of whole and cut fruits and vegetables. However, plastic packaging is a significant environmental concern globally. Biopolymer based films and/or coatings are environment-friendly alternative packaging for food. But, these biopolymers, derived from plant, animal and microbial sources, lack some of the primary physico-chemical and mechanical properties compared to conventional plastic packaging. Reinforcement of biopolymer with nanomaterials addresses these shortcomings, and adds functional properties such as antimicrobial and/or antioxidant activities to the nanocomposites. Organic (e.g. nanocellulose fibrils), and inorganic (e.g. montmorillonite, zinc oxide, silver) nanomaterials are effective in achieving these improvements in biopolymer based nanocomposite. Plant-extracts and compounds derived from plant (e.g. essential oil) are also effective in imparting antimicrobial and antioxidant properties to biopolymer based nanocomposites. This is an extensive review of research works on effectiveness of biopolymer based nanocomposite films and coatings used for packaging of whole and cut fruits and vegetables to extend their shelf-life. Numerous reports have demonstrated effectiveness of biopolymer based nanocomposites in improvement in shelf-life of packaged and/or coated whole and cut fruits and vegetables by at least 4-5 days to as much as a few months. Highlights Fresh produce are perishable commodities requiring package or coating. Conventional plastics and waxes are major environmental and health concerns. Biopolymer based nanocomposites are environment-friendly alternatives. These nanocomposite films and coatings are effective in enhancing shelf-life.
Zinc oxide nanoparticles (ZnONPs) were synthesized by green protocol using Mimusops elengi fruit ... more Zinc oxide nanoparticles (ZnONPs) were synthesized by green protocol using Mimusops elengi fruit extract as a novel natural resource. The synthesized particles were polyhedral (mostly hexagonal) in shape between 14 - 48 nm with an average size of 24.75 ± 0.78 nm. Nano zinc oxide (ZnO) at concentrations of 2% (w/w) and 4% (w/w), were incorporated into agar matrix. Solution casting method was used to fabricate the bionanocomposite films with ZnONPs in agar. Surface morphology, particle size, crystallinity, thermal stability and functional groups were determined using SEM, TEM, XRD, TGA and FTIR, respectively. Loading of ZnONPs in composite films improved thermal stability, elongation and film thickness, whereas tensile strength and transparency decreased. The films were used for packaging of green grapes, and appearance of the fruit was observed during ambient storage. Grapes packaged in composite films showed fresh appearance up to 14 and 21 days in ambient conditions for 2% (w/w) and 4% (w/w) ZnONPs in films, respectively. The results showed the potential of the fabricated agar-ZnO nanocomposite film as a promising packaging material to enhance postharvest shelf-life of fresh fruits like green grapes.
Internalization of Escherichia coli O157:H7 in nonintact beef products during mechanical tenderiz... more Internalization of Escherichia coli O157:H7 in nonintact beef products during mechanical tenderization or during injection of marination and tenderization ingredients is of concern if such products are undercooked. This study tested organic acids (0.2% citric acid and 0.3% acetic acid), potassium and calcium salts (1.8% potassium lactate, 0.63% calcium lactate, 0.86% calcium ascorbate, and 0.23% calcium chloride), and sodium chloride (2.5%) for their influence on thermal destruction of E. coli O157:H7 in ground beef serving as a model system. Ground beef batches (700 g; 5% fat) were mixed with equal volumes (22 ml) of each treatment solution or distilled water and portions (30 g) of treated ground beef were extruded in test tubes (2.5 by 10 cm). A five-strain mixture of E. coli O157:H7 (0.3 ml; 7 log CFU/g) was introduced at the center of the sample with a pipette. After overnight storage (4 degrees C), simulating product marination, samples were heated to 60 or 65 degrees C internal temperature, simulating rare and medium rare doneness of beef, in a circulating water bath. At 65 degrees C, treatments with citric and acetic acid showed greater (P < 0.05) reduction (4 to 5 log CFU/g) of E. coli O157:H7 than all the other ingredients and the control (3 to 4 log CFU/g). Sodium chloride reduced weight losses (16 to 18% compared with 20 to 27% by citric or acetic acid) and resulted in a 4-log reduction in counts during cooking to 65 degrees C. Ingredients such as citric or acetic acid may improve thermal inactivation of E. coli O157:H7 internalized in nonintact beef products, while sodium chloride may reduce cooking losses in such products.
International journal of clinical and experimental medicine, 2015
A green method of Silver nanoparticles (AgNPs) preparation has been established. This method depe... more A green method of Silver nanoparticles (AgNPs) preparation has been established. This method depends on reduction of silver nitrate with soluble starch. The formation of AgNPs was observed by the color change from colorless to dark brown through the starch addition into silver nitrate solution. It was observed that use of starch makes convenient method for the synthesis of silver nanoparticles and can reduce silver ions into the produced silver nanoparticles within one hour of reaction time without using any harsh conditions. The prepared silver nanoparticles were characterized by using UV-visible spectroscopy and evaluated for its antimicrobial activity. The synthesized green AgNPs showed a potential antibacterial activity that was stronger against Gram positive pathogenic bacteria (Staphylococus aureus and Streptococus pyogenes) than against Gram negative pathogenic bacteria (Salmonella typhi, Shigellasonnei and Pseudomonas aeruginosa). Inhibition zones diameter of antibacterial a...
Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farm... more Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farmers in Minnesota were conducted to determine the coliform count and the prevalence of Escherichia coli, Salmonella, and E. coli O157:H7. A total of 476 and 129 produce samples were collected from 32 organic and 8 conventional farms, respectively. The samples included tomatoes, leafy greens, lettuce, green peppers, cabbage, cucumbers, broccoli, strawberries, apples, and seven other types of produce. The numbers of fruits and vegetables was influenced by their availability at participating farms and varied from 11 strawberry samples to 108 tomato samples. Among the organic farms, eight were certified by accredited agencies and the rest reported the use of organic practices. All organic farms used aged or composted animal manure as fertilizer. The average coliform counts in both organic and conventional produce were 2.9 log most probable number per g. The percentages of E. coli-positive sam...
Microbiological analyses of fruits and vegetables produced by farms in Minnesota and Wisconsin we... more Microbiological analyses of fruits and vegetables produced by farms in Minnesota and Wisconsin were conducted to determine coliform and Escherichia coli counts and the prevalence of E. coli, Salmonella, and E. coli O157:H7. During the 2003 and 2004 harvest seasons, 14 organic farms (certified by accredited organic agencies), 30 semiorganic farms (used organic practices but not certified), and 19 conventional farms were sampled to analyze 2,029 preharvest produce samples (473 organic, 911 semiorganic, and 645 conventional). Produce varieties included mainly lettuces, leafy greens, cabbages, broccoli, peppers, tomatoes, zucchini, summer squash, cucumber, and berries. Semiorganic and organic farms provided the majority of leafy greens and lettuces. Produce samples from the three farm types had average coliform counts of 1.5 to 2.4 log most probable number per g. Conventional produce had either significantly lower or similar coliform populations compared with the semiorganic and organic...
The demand for fresh fruits and vegetables as popular food choices in our daily diet has been inc... more The demand for fresh fruits and vegetables as popular food choices in our daily diet has been increasing in recent years. As consumers are becoming increasingly aware of the potential health benefits, they are consuming more fresh produce in their diets. The market for fresh ...
This study evaluated chemical tenderizers and cooking methods to inactivate Escherichia coli O157... more This study evaluated chemical tenderizers and cooking methods to inactivate Escherichia coli O157:H7 in ground beef patties (model system for non-intact beef). Ground beef was inoculated with E. coli O157:H7 and mixed with (i) nothing (control), (ii) calcium chloride (CC) and flavoring agents (FA), (iii) CC, FA, and acetic acid (AA), (iv) sodium chloride (SC), sodium tripolyphosphate (ST), and potassium lactate (PL), and (v) the combination of SC, ST, PL, and AA. Patties were stored in aerobic or vacuum bags at − 20, 4, and 12°C. Samples were grilled, broiled, or pan-fried to 60 or 65°C. Total bacterial and E. coli O157:H7 populations remained unchanged during storage. Broiling was more effective in reducing E. coli O157:H7 than grilling and pan-frying, and acidified tenderizers reduced E. coli O157:H7 more than non-acidified tenderizers in broiling. Higher reductions were observed at 65°C than 60°C in broiled and grilled samples. These results indicate that acidified tenderizers and broiling may be useful in non-intact beef safety.
This study evaluated the effects of meat binding or restructuring formulations, including salt/ph... more This study evaluated the effects of meat binding or restructuring formulations, including salt/phosphate, algin/calcium, Activa TM RM, and Fibrimex R , with or without 0.27% (wt/wt) lactic acid, on thermal inactivation of internalized Escherichia coli O157:H7 in ground beef, serving as a model system for restructured products. Ground beef batches (700 g; approximately 5% fat) were mechanically mixed with a 5-strain composite of E. coli O157:H7 (7 log CFU/g) and then with the restructuring formulations. Product portions (30 g) were extruded into plastic test tubes (2.5 × 10 cm) and stored at 4 • C (18 h), before heating to 60 or 65 • C in a circulating water bath to simulate rare or medium-rare doneness of beef, respectively. Cooking to 60 or 65 • C reduced (P < 0.05) bacterial counts of control samples by 1.8 and 3.2 log CFU/g, respectively. Thermal destruction at 60 • C was not different (P > 0.05) among all treatments and the control. At 65 • C, greater (P < 0.05) thermal inactivation of E. coli O157:H7, as compared to the control, was obtained in samples treated with lactic acid alone (reductions of 4.9 log CFU/g), whereas for all other treatments, microbial destruction (reductions of 2.2 to 4.5 log CFU/g) was comparable (P > 0.05) to that of the control. Cooking weight losses were lower (P < 0.05) in salt/phosphate samples (<1%) compared to other formulations and the control (7.4% to 15.9%). Findings indicated that, under the conditions examined, restructuring of beef with salt/phosphate, algin/calcium, Activa TM RM, or Fibrimex R did not affect inactivation of internalized E. coli O157:H7 in undercooked (60 or 65 • C) samples, whereas inclusion of lactic acid (0.27%) in nonintact beef products enhanced pathogen destruction at 65 • C.
Escherichia coli O157:H7 is a pathogenic bacterium that causes enterohaemorrhagic infections. Acc... more Escherichia coli O157:H7 is a pathogenic bacterium that causes enterohaemorrhagic infections. According to the Centers for Disease Control and Prevention, this organism is responsible for more than 73 000 human cases every year in the United States, and the majority of those infections are sporadic cases (Mead et al. 1999). In recent years, however, there has been a decline in the incidence of E. coli O157:H7 (CDC 2005). Infections caused by E. coli O157:H7 are typically associated with the consumption of contaminated foods, but approximately half of all outbreaks are transmitted by other routes such as water and person to person (Rangel et al. 2005). Because cattle are a primary natural reservoir, the risk factors identified for sporadic cases include consumption of poorly cooked ground beef, visiting and living on a farm, living in agricultural areas, contact with farm animals and contact with cattle manure (Michel et al. 1999; Kassenborg et al. 2004). Cattle and sheep manure can serve as the vehicle for E. coli O157:H7 contamination of fruits, vegetables, water and soil (Hilborn et al. 1999; Chalmers et al. 2000; Rangel et al. 2005). This pathogen can also be transmitted directly from manure; this infection route has been implicated in several outbreaks (Duffy 2003). In 2000, 20
... Thermal Inactivation of Escherichia coli O157:H7 in Beef Treated with Marination and Tenderiz... more ... Thermal Inactivation of Escherichia coli O157:H7 in Beef Treated with Marination and Tenderization Ingredients AVIK MUKHERJEE, YOHAN YOON, KEITH E. BELK, JOHN A. SCANGA, GARY C. SMITH, AND JOHN N. SOFOS* ...
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