Papers by Dr. Edward Richter
Pediococcus acidilactici PO2 Bacteriocin Production in Whey Permeate and Inhibition of Listeria monocyfogenes in Foods
Journal of Food Science, 1993
ABSTRACTGrowth of Pediococcus acidiluctici PO2 and production of associated bacteriocin (pediocin... more ABSTRACTGrowth of Pediococcus acidiluctici PO2 and production of associated bacteriocin (pediocin PO2) were demonstrated in whey permeate (WP) supplemented with 0.5–4% yeast extract (YE). Initial pH 6.5 (without PH regulation during fermentation) wag optimal for production of uediocin PO2 in WP containing 2% YE. A pediocin‐rich dairy ingredient (PRDI) powder was made of the fermented WP and applied in heat‐treated whole milk and pasteurized liquid whole egg. PRDI in‐hibited Listeria monocyfogenes in milk. L. monocytogenes was inhib‐ited by untreated liquid whole egg and PRDI appeared to contain a factor that offsets the inherent antilisterial action of the egg product.
Journal of Food Protection, 1982
Salmonella gallinarom and Salmonella pullorom have been considered as one serovar, S. gallinarom-... more Salmonella gallinarom and Salmonella pullorom have been considered as one serovar, S. gallinarom-pullorom or S. gallinarom. This serovar possesses group D somatic antigens with no flagellar antigen. Reportedly S. gallinarom differs from S. pullorom in dulcitol fermentation. This reaction is positive, but delayed up to 5 d for S. gallinarom and negative for S. pullorom. Gas-liquid chromatography of organic acid by-products from a dulcitol medium was performed on 10 isolates of each biovar. Viable plate counts confirmed approximately the same number of organisms per ml of culture. Results of pH determinations supported gas-liquid chromatographic analysis of more acid formation in all S. gallinarom cultures as compared with the S. pullorom cultures after incubation for 24 h. A quantitative measurement of succinic acid resulted in confirmation of the differences in metabolic function of both biovars. The additional test procedure of gas-liquid chromatography of organic acid by-products ...
Journal of Food Processing and Preservation, 1990
Although the idea of electrical treatment of foods for microbial control is not new, the data ava... more Although the idea of electrical treatment of foods for microbial control is not new, the data available on nonthermal effects of electriciry are limited and inconclusive. An understanding of such effects would be useful in developing new methods for microbial inactivation. The present review discusses a number of different methods of electrical treatment and their nonthermal effects on microorganisms. Subjects discussed include electric pasteurization of milk, electrohydraulic shock, electroporation, and electroconductive heating. Information relating to mechanisms contributing to microbial death is summarized and discussed.
Applied and Environmental Microbiology, 1983
Some foods contain low numbers of microbes that may be difficult to enumerate by the plate count ... more Some foods contain low numbers of microbes that may be difficult to enumerate by the plate count method due to small food particles that interfere with the counting of colonies. Ludox colloidal silicon was coated with reducing agents to produce a nontoxic density material. Food homogenates were applied to a layered 10 and 80% mixture of modified Ludox and centrifuged at low speed. The top and bottom of the tube contained the food material, and the Ludox-containing portion was evaluated by conventional pour plate techniques. Plate counts of the Ludox mixture agreed with plate counts of the food homogenate alone. The absence of small food particles from pour plates resulted in a plate that was more easily read than pour plates of the homogenate alone. Modified Ludox was evaluated for its effect on bacteria at 4°C during a 24-h incubation period. No inhibition was observed. This method is applicable to food products, such as doughnuts, spices, tomato products, and meat, in which small ...
Applied and Environmental Microbiology, 1990
Two types of commercial products for feeding zoo animals (a frozen meat product, referred to as z... more Two types of commercial products for feeding zoo animals (a frozen meat product, referred to as zoo food, and a dry product, referred to as dry food) were microbiologically examined for spoilage organisms (aerobic, psychrotrophic, coliform, Escherichia coli, mold, and yeasts) and pathogens (Salmonella spp., Listeria monocytogenes, and Campylobacterjejuni). Levels of microorganisms in frozen ground zoo food were compared with those in frozen ground beef and frozen ground turkey meat. The level of microbial contaminants in frozen ground zoo meat was found to be similar to that in frozen ground beef and higher than that in frozen ground turkey meat. Sixty percent of the frozen zoo meat samples were Salmonella positive, and all of the samples were L. monocytogenes positive. Dry zoo food was documented to have microbial levels lower than those in frozen zoo meat; the pathogen levels were <1/25 g of food. Defrosting zoo meat at 10, 25, and 37°C for 24 h showed that 10°C is the best temperature for defrosting frozen ground zoo meat loaves (length, 9 in. [22.8 cm]; radius, 2 in. [5.1 cm]) without affecting the microbiological quality or safety of the product.
Antimicrobial activity of banana puree
Food Microbiology, 1989
... Chaudhry and Frooqi, 1970 TM Chaudhry and MAR Frooqi, Chemical composition of guava and banan... more ... Chaudhry and Frooqi, 1970 TM Chaudhry and MAR Frooqi, Chemical composition of guava and banana fruits grown in Hyderabad region. Pakistan J. Sci. Ind. ... 18851890. Ketiku, 1973 AO Ketiku, Chemical composition of unripe (green) and ripe plantain (Musa paradisiaca). ...
Applied and Environmental Microbiology, 2000
Both 25-g single-size ground beef samples and 375-g composite ground beef samples were tested by ... more Both 25-g single-size ground beef samples and 375-g composite ground beef samples were tested by a method combining an immunomagnetic separation (IMS) technique with a sandwich enzyme-linked immunosorbent assay (ELISA) system (IMS-ELISA). The results demonstrated that IMS-ELISA could detect the target, Escherichia coli O157:H7, at the level of 10 −1 CFU/g of sample in either the 25- or 375-g sample size.
Journal of Food: Microbiology, Safety & Hygiene, 2017
Rapid and specific identification of foodborne pathogens is important for not only for food produ... more Rapid and specific identification of foodborne pathogens is important for not only for food producers but also consumers as well as food safety authorities. Foods can harbor pathogen bacteria of different species, thus it is also important to be able to detect different pathogens simultaneously from the food samples even though they are in very low number. Detection of bacteria depends on different factors such as the initial number, food matrix, sensitivity of the method, competitor microflora and physical state of the bacteria whether they are injured or not. Simultaneous detection of different bacteria yet adds another hurdle for the level of detection, and thus, different approaches have developed and tested so far to optimize the maximum recovery.
Journal of Food Safety, 1994
Thirty seven strains of lactobacilli and leuconostocs were screened for bacteriocin production. A... more Thirty seven strains of lactobacilli and leuconostocs were screened for bacteriocin production. A bacteriocin-like substance (designated lacidin A) was detected in culture filtrate of Lactobacillus acidophilus OSU133. Lacidin A inhibited Enterococcus faecalis, L. acidophilus, Lactobacillus delbrueckii subsp. lactis, and Staphylococcus aureus. The bacteriocinogenic nature of lacidin A was confirmed by eliminating the inhibitory effects of acid, hydrogen peroxide and phage and by loss of activity upon hydrolysis with proteolytic enzymes. The bacteriocin is relatively heat-stable and has considerable bactericidal action against S. aureus in phosphate buffer. Lacidin A also demonstrated bacteriostatic action against S. aureus in brain heart infusion and heat-treated milk and liquid whole egg.
Ultraviolet Light Disinfection: The Energy, Time, and Distance to Eradicate Multi-Drug Resistant Organisms and Clostridium difficile?
ABSTRACT
Microbial safety and shelf-life of apple juice and cider processed by bench and pilot scale PEF systems
Innovative Food Science …, 2000
... of this study were to determine the inactivation of E. coli O157:H7 inoculated in apple juice... more ... of this study were to determine the inactivation of E. coli O157:H7 inoculated in apple juice by PEF processing on a bench scale and to identify if the PEF processing on a pilot plant scale is effective in extending the shelf-life of fresh apple cider and reconstituted apple juice. ...
Uploads
Papers by Dr. Edward Richter