Fermented foods play a very important role in Cambodian health and nutrition,as well as other developing countries where food preservation methods may be limited.SIENG,a Khmer fermented soybean product,naturally conta...Fermented foods play a very important role in Cambodian health and nutrition,as well as other developing countries where food preservation methods may be limited.SIENG,a Khmer fermented soybean product,naturally contains both beneficial and pathogenic microorganisms.Traditional fermentation that relies on natural microbial flora and environmental conditions results in variable product quality and can lead to spoilage.A starter culture such as Bacillus subtilis can ensure the safety and stability of the products.The objective of this study is to control the growth of Gram positive pathogens contaminated into traditional fermented soybean(SEING)by using antimicrobial Bacillus subtilis isolated from the same kind of food.Out of 120 SIENG samples,49 B.cereus strains were isolated,and 12 of B.cereus were positively synthesized compared with the lyophilized control enterotoxin.Two of these strains(BTM8-7 and BTM8-8)produced high levels of enterotoxin.We identified five Bacillus strains with the ability to fight against indicator pathogenic microorganisms.Among the five strains,B.CeM6-2 had the highest activity level against Lactobacillus plantrum ATCC 8014 and the largest diameter.B.CeM6-2 tolerated up to 20 h at 30℃ and 22 h at 37℃.In testing the strains with PK and PK-PMSF enzymes,bacteriocin produced by the strain B.CeM6PK untreated and B.CeM6-2PK-PMSF had a significantly stronger ability to suppress all the pathogenic indicators from 0 h to 47 h compared to the B.CeM6-2PK.Moreover,CeM6-2 outperformed the Miyagino strains,as it actively produced bacteriocin that fought against all four indicator strains of Gram positive and lactic acid groups,especially against Listeria monocytogenes,Streptococcus pyrogene,Leuconostoc mesenterids and L.plantarum,from 0 h-58 h and 0 h-40 h at 35℃.CeM6-2(1%)strain had the highest ability to fight against B.cereus at 24 h and at 34 h to 44 h incubation as well.CeM6-2(10:0 mL)and CeM6-2(9:1 mL)have the strongest ability to fight against B.cereus at room temperature(48 h and 72 h).The longer incubation and time at room temperature produce the highest level of bacteriocin.Thus,bacteriocins produced by B.CeM6-2 can be used as a preservative in food processing industries to avoid food spoilage even in higher temperatures and time.展开更多
Cold-chain is a well-known method for reducing postharvest losses and low-cost cooling technology has not previously been tested as part of postharvest handling in Cambodia.The objective of this study was to measure p...Cold-chain is a well-known method for reducing postharvest losses and low-cost cooling technology has not previously been tested as part of postharvest handling in Cambodia.The objective of this study was to measure postharvest loss,quality changes,and safety concerns of Chinese cabbage(Brassica campestris L.ssp.pekinensis),during transportation using a cold-chain and compared to current farmers’employing ambient-chain practices.The quality and safety of Chinese cabbage were further evaluated by using ambient storage and Coolbot-powered cold chamber storage with and without modified atmosphere packaging(MAP).The samples were transported from farm sources in Battambang Province to a Phnom Penh specialty wholesale market.Postharvest loss was evaluated by measuring weight loss and visual quality measurements,in addition to various physiochemical and nutritional quality measurements.In addition,food safety was evaluated by quantifying total coliforms and Enterobacteriaceae,as well as the Salmonella spcies,and Escherichia coli.The results revealed that the cold-chain avoided postharvest loss,as indicated by produce weight gain of 14%on market arrival due to rehydration while inside the ice box during transport.In contrast,the traditional practice of ambient transport(28-31°C,62-78%relative humidity)resulted in very high postharvest loss,comprising 11%weight loss and 10%visual quality loss,for a total loss of 21%.Moreover,leaf yellowing found no marked influence on shelf life as L*,a*and b*values did not greatly differ with treatment.The total soluble solids(TSS),titratable acidity(TA),pH and vitamin C content were not significantly affected during storage.Food safety indicators(coliforms,Enterobacteriaceae,Salmonella and Escherichia coli)were lower in cold-chain storage than ambient-chain with lower counts of coliform bacteria,Enterobacteriaceae,and Salmonella spp.than traditionally handled produce.Escherichia coli was detected only in cold-chain produce.MAP had no effect on these food safety indicators.展开更多
The objective of this study was to isolate Bacillus subtilis produced Bacteriocin from Khmer traditional fermented soybean to control the growth of pathogenic bacteria from 120 SIENG samples from 9 different loca...The objective of this study was to isolate Bacillus subtilis produced Bacteriocin from Khmer traditional fermented soybean to control the growth of pathogenic bacteria from 120 SIENG samples from 9 different local open markets in Phnom Penh, 1 local open market and 2 local producers in Kandal province in Cambodia. 119 out of 120 samples were positive with Bacillus subtilis strains. Fifteen of these isolated strains exhibited antimicrobial activity to Lactobacillus plantarum by agar well diffusion assay and one of them （CeM6-7 strain） exhibited strongest antimicrobial activity. The filtered supernatant of this strain also suppressed the growth of several Gram-positive pathogens （such as Staphylococcus aureus） or lactic acid bacteria in broth. The filtrate could also suppress the growth of L. plantarum inoculated into soymilk. Antimicrobial B. subtilis strain CeM6-7 is thought to be applicable for making a starter culture to produce much safe fermented soybean foods by suppressing the growth of naturally contaminated B. cereus or S. aureus during production. In addition, the use of this starter culture may contribute to prevent spoilage or quality loss of soybean products caused by the over growth lactic acid bacteria or other Gram-positive bacteria.展开更多
文摘Fermented foods play a very important role in Cambodian health and nutrition,as well as other developing countries where food preservation methods may be limited.SIENG,a Khmer fermented soybean product,naturally contains both beneficial and pathogenic microorganisms.Traditional fermentation that relies on natural microbial flora and environmental conditions results in variable product quality and can lead to spoilage.A starter culture such as Bacillus subtilis can ensure the safety and stability of the products.The objective of this study is to control the growth of Gram positive pathogens contaminated into traditional fermented soybean(SEING)by using antimicrobial Bacillus subtilis isolated from the same kind of food.Out of 120 SIENG samples,49 B.cereus strains were isolated,and 12 of B.cereus were positively synthesized compared with the lyophilized control enterotoxin.Two of these strains(BTM8-7 and BTM8-8)produced high levels of enterotoxin.We identified five Bacillus strains with the ability to fight against indicator pathogenic microorganisms.Among the five strains,B.CeM6-2 had the highest activity level against Lactobacillus plantrum ATCC 8014 and the largest diameter.B.CeM6-2 tolerated up to 20 h at 30℃ and 22 h at 37℃.In testing the strains with PK and PK-PMSF enzymes,bacteriocin produced by the strain B.CeM6PK untreated and B.CeM6-2PK-PMSF had a significantly stronger ability to suppress all the pathogenic indicators from 0 h to 47 h compared to the B.CeM6-2PK.Moreover,CeM6-2 outperformed the Miyagino strains,as it actively produced bacteriocin that fought against all four indicator strains of Gram positive and lactic acid groups,especially against Listeria monocytogenes,Streptococcus pyrogene,Leuconostoc mesenterids and L.plantarum,from 0 h-58 h and 0 h-40 h at 35℃.CeM6-2(1%)strain had the highest ability to fight against B.cereus at 24 h and at 34 h to 44 h incubation as well.CeM6-2(10:0 mL)and CeM6-2(9:1 mL)have the strongest ability to fight against B.cereus at room temperature(48 h and 72 h).The longer incubation and time at room temperature produce the highest level of bacteriocin.Thus,bacteriocins produced by B.CeM6-2 can be used as a preservative in food processing industries to avoid food spoilage even in higher temperatures and time.
基金the generous support of the American People provided through the United States Agency for International Development(USAID)to the following:Building Safe Vegetable Value Chains in Cambodia Program through the Feed the Future Horticulture Innovation Lab for Collaborative Research at the University of California Davis,subaward No.09-002945-130 to KL and GMYthe Borlaug Global Food Security Graduate Research Program as part of the U.S.government’s global hunger and food security initiative called Feed the Future,grant No.13076416 to KLand the Center of Excellence on Sustainable Agricultural Intensification and Nutrition(CE SAIN)of the Royal University of Agriculture through the Feed the Future Innovation Lab for Collaborative Research on Sustainable Intensification at Kansas State University(USAID)under Cooperative Agreement No.AID-OAA-L-14-00006.Additional support was provided by Sierra College and awards from the University of California President’s and Chancellor’s Postdoctoral Fellowship Program to KL.
文摘Cold-chain is a well-known method for reducing postharvest losses and low-cost cooling technology has not previously been tested as part of postharvest handling in Cambodia.The objective of this study was to measure postharvest loss,quality changes,and safety concerns of Chinese cabbage(Brassica campestris L.ssp.pekinensis),during transportation using a cold-chain and compared to current farmers’employing ambient-chain practices.The quality and safety of Chinese cabbage were further evaluated by using ambient storage and Coolbot-powered cold chamber storage with and without modified atmosphere packaging(MAP).The samples were transported from farm sources in Battambang Province to a Phnom Penh specialty wholesale market.Postharvest loss was evaluated by measuring weight loss and visual quality measurements,in addition to various physiochemical and nutritional quality measurements.In addition,food safety was evaluated by quantifying total coliforms and Enterobacteriaceae,as well as the Salmonella spcies,and Escherichia coli.The results revealed that the cold-chain avoided postharvest loss,as indicated by produce weight gain of 14%on market arrival due to rehydration while inside the ice box during transport.In contrast,the traditional practice of ambient transport(28-31°C,62-78%relative humidity)resulted in very high postharvest loss,comprising 11%weight loss and 10%visual quality loss,for a total loss of 21%.Moreover,leaf yellowing found no marked influence on shelf life as L*,a*and b*values did not greatly differ with treatment.The total soluble solids(TSS),titratable acidity(TA),pH and vitamin C content were not significantly affected during storage.Food safety indicators(coliforms,Enterobacteriaceae,Salmonella and Escherichia coli)were lower in cold-chain storage than ambient-chain with lower counts of coliform bacteria,Enterobacteriaceae,and Salmonella spp.than traditionally handled produce.Escherichia coli was detected only in cold-chain produce.MAP had no effect on these food safety indicators.
文摘The objective of this study was to isolate Bacillus subtilis produced Bacteriocin from Khmer traditional fermented soybean to control the growth of pathogenic bacteria from 120 SIENG samples from 9 different local open markets in Phnom Penh, 1 local open market and 2 local producers in Kandal province in Cambodia. 119 out of 120 samples were positive with Bacillus subtilis strains. Fifteen of these isolated strains exhibited antimicrobial activity to Lactobacillus plantarum by agar well diffusion assay and one of them （CeM6-7 strain） exhibited strongest antimicrobial activity. The filtered supernatant of this strain also suppressed the growth of several Gram-positive pathogens （such as Staphylococcus aureus） or lactic acid bacteria in broth. The filtrate could also suppress the growth of L. plantarum inoculated into soymilk. Antimicrobial B. subtilis strain CeM6-7 is thought to be applicable for making a starter culture to produce much safe fermented soybean foods by suppressing the growth of naturally contaminated B. cereus or S. aureus during production. In addition, the use of this starter culture may contribute to prevent spoilage or quality loss of soybean products caused by the over growth lactic acid bacteria or other Gram-positive bacteria.
