Salmonella enterica Typhimurium is a common foodborne pathogen, and ready-to-eat (RTE) seafood is a potential source of Salmonella outbreaks. Lactic acid is a classical preservative in the meat industry and it is used with high efficacy to sanitize meat surfaces. Cetylpyridinium chloride (CPC) is a cationic quaternary ammonium compound proposed for use as a pathogen intervention substance. Cetylpyridinium chloride activity can be potentially affected by interactions between cetylpyridinium chloride and lactic acid. Lactic acid treatment (up to 1%) reduced Salmonella Typhimurium counts by less than 0.5 log cfu/g. Cetylpyridinium chloride treatment (up to 1%) reduced Salmonella Typhimurium counts by 0.9 log cfu/g. Cetylpyridinium chloride treatment at 18 and 45°C reduced populations of Salmonella Typhimurium by 1.34 and 1.14 log cfu/g. Combined treatment with cetylpyridinium chloride and lactic acid at 18 and 45°C decreased Salmonella Typhimurium counts by 0.83 log cfu/g and 1.05 log cfu/g. The single intervention of cetylpyridinium chloride was more effective than lactic acid used alone or combination of cetylpyridnium chloride and lactic acid to reduce Salmonella Typhimurium attached on ready-to-eat shrimp.

Enterobacter sakazakii has been associated with powdered infant formula outbreaks which caused high mortality rate illnesses in infants in recent years. Current research was mainly focused on searching for natural antimicrobial agents which may be incorporated into baby foods to control this emerging pathogen. Yogurt and muscadine products were used in this study. The antimicrobial effects of yogurt were evaluated on agar plates and in a simulated gastrointestinal model. In the agar spot tests, diluted yogurt sample containing lactic acid bacteria at 106 CFU/mL was antagonistic toward E. sakazakii. However, the antimicrobial effect of yogurt on E. sakazakii in the simulated GI model was not noted. Certain numbers of tested E. sakazakii and lactic acid bacteria in yogurt were able to survive the acidic gastric condition and recovered in the intestinal model. By measuring the viable E. sakazakii cells in liquid cultures, the strong antimicrobial activities of muscadine juices and muscadine seed extracts were demonstrated. Within two hours, all inoculated E. sakazakii at 106 CFU/mL were decreased to non-detectable level. Juice and seed extract from dark-skinned muscadine demonstrated stronger antimicrobial activities than those form white-skinned muscadine. The characteristics of muscadine juices and seed extracts were also analyzed. The high phenolics and organic acid contents, such as ellagic, gallic, tannic, and tartaric acids in muscadine were correlated to the inhibitory effect observed.

No description available.

Shellfish waste obtained from seafood processing plants contains chitin, protein and calcium carbonate. Chitin is a versatile biopolymer with many applications. Conventionally, chitin is separated from calcium carbonate and protein by acid and alkali respectively. In this project, a biotechnological approach was applied to recover chitin from scampi (Nephrops norvegicus) waste using lactic acid bacteria (LAB) to produce lactic acid from glucose which lowers the pH of the mixture, thus preserving the waste from spoilage. The acid also dissolves the calcium carbonate and under these conditions native enzymes breakdown the protein (autolysis), thus affording a substantial amount of purification of chitin. LAB were isolated and identified from various shellfish waste fermentations. Studies on their acid-producing ability revealed a few potentially good strains, identified as Lactobacillus paracasei, Lactobacillus plantarum and Pediococcus sp. The strain of Lactobacillus paracasei was used as a starter culture in the fermentation of shellfish waste in a horizontal rotating bioreactor in order to evaluate the feasibility of the process. The design of the bioreactor was such that it enabled separation of solid and liquid end products during fermentation. Several important fermentation parameters were studied including mode of rotation, concentration of glucose, temperature, rotation rates, loading capacity, type and particle size of waste. Partial purification of the scampi waste was achieved using both batch and fed batch operation, but in the latter, improved purification was achieved at the cost of increased glucose consumption and extended fermentation times. Whilst higher temperatures increased the rates of fermentation, higher rotation rates seemed to have the reverse effect. Mincing the waste helped to increase breakdown of protein whilst larger particles tended to undergo rapid spoilage. Analysis of the chitin product enabled this method to be compared with the conventional method. The results obtained showed that this method is capable of saving large volumes of chemicals and besides producing chitin, the protein liquor by-product could also be used as an ingredient in an animal feed which is not possible by the conventional method.

Please read the abstract in the section 00front of this document / Dissertation (MSc Agric (Food Science))--University of Pretoria, 1999. / Food Science / unrestricted

The diploma thesis deals with the growth of biomass and production of selected metabolit–lactic acid by thermophilic bacteria Bacillus coagulans. The resulting selected metabolite was determined by HPLC method. Cultivations of this genus were performed on synthetic media, where the influence of carbohydrate used as carbon source was tested. Lactose was more suitable fot growth of biomass and glucose for production of lactic acid. On natural whey media the influence of different conditions were tested. The highest yields of biomass and production of lactic acid were observed on enriched whey medium. The last part deals with comparing the production of biomass and metabolites, depending on the volume of media. There were compared selected bioengineering characteristics of all cultivations.

No description available.

This diploma thesis deals with senthesis of lactic acid ethyl ester from slats of lactic acid. The literature review has been processed in the theoretical part of the diploma thesis. It is focused on manufacturing technologies of lactic acid esters, mainly on ethyl lactate by conventional and non-conventional ways of producing. Also the literature review involves producing of lactic acid and slats of lactic acid by fermentation because subsequently is possible produce ethyl lactate from that two substances. The laboratory apparatus for preparation of ethyl lactate and methyl lactate has been designed, realized and verificated function of it in the experimental part. There were carried out laboratory experimnets for production ethyl lactate and methyl lactate in this apparaturs.

Call number: LD2668 .T4 1985 C84 / Master of Science

Master of Science / Department of Grain Science and Industry / Praveen V. Vadlani / Paper mill sludge is a solid waste generated from the paper-making industry. Cellulose in the sludge can be hydrolyzed into glucose using a cellulase enzyme complex, which can then be fermented to produce value added chemicals, such as lactic acid. The enzyme requirement for hydrolysis of the cellulose in paper sludge was benchmarked against paper pulp. Enzymatic requirements for complete conversion of cellulose in paper pulp was found to be 12 fpu cellulase, supplemented with 5 egu of beta-glucosidase per gram of cellulose. However, beta-glucosidase supplementation had to be increased to 38 egu to obtain a similar level of hydrolysis in the case of paper sludge indicating a decrease in enzyme activity due to sludge components. Response Surface Methodology (RSM) was used to study the lactic acid yield from paper sludge using enzyme dosage and temperature as parameters and operating in simultaneous saccharification and fermentation (SSF) mode. Maximum lactic acid yield of 0.75 g/g glucose was obtained within 36 hours using 10 fpu cellulase supplemented with 32 egu beta-glucosidase at a temperature of 39 degree C. Using the optimization function of the software, the optimal operational conditions for paper sludge hydrolysis were found to be 9 fpu cellulase, 12.5 egu beta-glucosidase at 40 degree C which resulted in a lactic acid yield of 0.58 g /g glucose. Lactic acid producing microbial cultures, Lactobacillus plantarum and Rhizopus oryzae were evaluated for fermentation of the pulp and sludge hydrolyzate at 125-ml shake flask and 2-L fermenter levels. In paper pulp media, the yields obtained by bacterial and fungal fermentations were 0.89 and 0.36 g/g glucose, respectively. In the case of paper sludge, the yield remained same, but inhibition of bacterial growth occurred. This resulted in lower substrate uptake and productivity than those obtained in paper pulp. On the other hand, fungal growth rate was enhanced due to the high solids content of paper sludge. The yield of lactic acid from paper sludge using L. plantarum and R. oryzae was 0.88 and 0.72 g/g glucose, respectively. Microbial cultures native to the sludge were isolated and evaluated for their performance of lactic acid production.