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Öğe Antimicrobial effect of some olive phenols in a laboratory medium(1993) Tunçel G.; Nergiz C.The minimum inhibitory concentration (MIC) of several phenolic compounds found in olive against four pathogenic bacteria in laboratory medium was determined. The results indicated that caffeic acid was the most effective compound. Copyright © 1993, Wiley Blackwell. All rights reservedÖğe Degradation of cyanogenic glycosides of bitter apricot seeds (Prunus armeniaca) by endogenous and added enzymes as affected by heat treatments and particle size(1998) Tunçel G.; Nout M.J.R.; Brimer L.Bitter apricot (Prunus armeniaca) seeds (kernels) are by-products of the apricot processing industry. They contain approximately 50-150 µMol/g (dry weight basis) of potentially toxic cyanogenic glycosides, mainly amygdalin and prunasin. The present paper deals with the degradation of these glycosides by endogenous and added enzymes in raw and blanched seeds of different particle sizes. A hot water blanching treatment of 20 min at 100°C was adequate to inactivate endogenous ß-glucosidase activity in raw bitter apricot seeds. In addition to raw seeds, such blanched seeds were used as an experimental model to investigate the effect of particle size and added individual enzyme preparations on the degradation of cyanogenic glycosides. Finely ground (< 2 mm) fractions showed increased glycoside degradation, supporting the hypothesis that particle size is a limiting factor for enzymic degradation. Our hypothesis that added pectinase activity would enhance degradation of glycosides by improving enzyme-substrate contact could not be affirmed. Furthermore, it was observed that substantial enzyme addition (ß-glucosidase) is required to fully degrade residual glycoside levels in raw and/or blanched seeds.Öğe Effect of different methods of soaking soya beans on the growth of Bacillus cereus, klebsiella pneumoniae and Staphylococcus aureus in tempeh(1990) Tunçel G.; Göktan D.Tempeh is usually made by fungal solid state fermentation of soaked and cooked soya beans. In this research the effect of different soaking conditions of soya beans on the growth of Bacillus cereus, Staphylococcus aureus and Klebsiella pneumoniae either alone or with a mixed inoculum of Rhizopus oligosporus and lactic acid bacteria was investigated. Natural acidification did not prevent the growth of undesirable bacteria. The acidification of soya beans soaked in water at 25°C for 24 h prevented the growth of S aureus. To prevent growth of S aureus in tempeh by chemical acidification it was necessary to add 0.6 % lactic and 0.06 % acetic acids and to adjust the pH to about 4.0. Copyright © 1990 John Wiley & Sons, LtdÖğe Effect of ingredients on quantitative recovery of Salmonella in raw meat balls(1988) Göktan D.; Tunçel G.Raw meat balls is a special Turkish meal, prepared from minced meat, bulgar, onion, garlic and different spices. In this experiment raw meat balls were prepared by using minced meat which was inoculated with Salmonella typhimurium at two different levels. Salmonella inoculated minced meat was also used in the experiment as a control. Samples were analysed at intervals. The lowest recovery of Salmonella was observed in raw meat balls which has been inoculated at the higher level. © 1988.Öğe The effect of vacuum packaging and gaseous atmosphere on microbial growth in tripe(1988) Göktan D.; Tunçel G.; Ünlütürk A.Changes in bacterial flora of tripe samples, stored at 4°C in air, vacuum packaged or in a CO2-enriched atmosphere were studied. Aerobic plate counts showed a rapid increase in samples stored in air reaching a level of 1·6 × 109/g from an initial level of 9·0 × 103/g. The aerobic bacterial population inhibited in both vacuum packed and CO2-enriched atmosphere storage. The shelf lives of samples stored in air, under vacuum packaging or in gas mixtures, were 4, 8 and 9 days, respectively. Enterobacteriaceae and anaerobic counts tended to be higher under vacuum storage than in a CO2-enriched atmosphere. The numbers of lactic acid-producing bacteria were generally found to be lower under vacuum storage than in gas mixtures. © 1989.Öğe The effects of grinding, soaking and cooking on the degradation of amygdalin of bitter apricot seeds(1995) Tunçel G.; Nout M.J.R.; Brimer L.More than 650 metric tonnes of bitter apricot seeds are produced in Turkey per year as a by-product from the fruit canning industry. The seeds contain the toxic cyanogenic glycoside amygdalin in amounts up to around 150 µmol/g fresh weight. The effect of grinding, soaking and cooking on the degradation of amygdalin to prunasin, benzaldehyde cyanohydrin and HCN, has been studied, as has the release of these cyanides into the soaking water. Analysis for total cyanogenic potential (TCP), cyanogenic glycosides and non-glycosidic cyanogens were thus made on a number of differently processed seed batches. The parameters were: particle size, soaking time and temperature, the presence of a natural microflora, and the duration of cooking. Great reductions were obtained for all three values measured, i.e. from the initial TCP of 85 µmol/g and down to around 2-4µmol/g. However, none of the products obtained were considered safe for human consumption, i.e. a further microbiological detoxification must be added. © 1995.Öğe Microbial degradation of amygdalin of bitter apricot seeds (Prunus armeniaca)(1995) Nout M.J.R.; Tunçel G.; Brimer L.Amygdalin is a cyanogenic glycoside occurring among others in almonds and bitter apricot seeds with interesting levels of dietary protein. Utilization of seeds for human or animal nutrition requires adequate detoxification. In the present paper, selected filamentous fungi (Mucor circinelloides, Penicillium nalgiovense) and yeasts (Hanseniaspora valbyensis, Endomyces fibuliger) were tested for their in-situ ability to decompose amygdalin. The latter (Endomyces fibuliger) was best able to grow on autoclaved bitter apricot seeds and detoxify them from 30 µMol CN g dry matter to less than 1 µMol CN g dry matter after 48 h of incubation at 27 °C. © 1995.Öğe Microbial quality, and effect of cooking on survival of Salmonella, in Kokariç(1991) Göktan D.; Tunçel G.; Ceylan S.A special preparation from the small intestine of lamb, called kokariç, is widely consumed in Turkey. In this study, Salmonella was not isolated from raw kokariç. Conventional ways of cooking, except precooking, destroyed Salmonella in artificially contaminated kokariç. The microbial quality of cooked kokariç bought from street sellers was not safe for public health consumption because of environmental contamination. © 1991.Öğe Simple screening procedure for microorganisms to degrade amygdalin(Kluwer Academic Publishers, 1993) Brimer L.; Tunçel G.; Nout M.J.R.Amygdalin is a cyanogenic glycoside occurring among others in almonds and bitter apricot seeds. Utilization of seeds for human or animal nutrition requires adequate detoxification. The present method for screening microbial cultures for their ability to degrade amygdalin is a convenient micro-titre version based on the picrate reaction principle. © 1993 Chapman & Hall.Öğe Toxicological, nutritional and microbiological evaluation of tempe fermentation with Rhizopus oligosporus of bitter and sweet apricot seeds(1990) Tunçel G.; Nout M.J.R.; Brimer L.; Göktan D.Bitter and sweet apricot seeds are by-products of the apricot processing industry. Bitter seeds, in particular, contain toxic levels of the cyanogenic substance amygdalin. Tempe was made from both kinds of seeds. The bitter seeds contain antimicrobial substances which must be removed by leaching and boiling prior to tempe fermentation. Apricot seed tempe had an agreeable taste. It contained approx. 21% (w/w) crude protein, 52% (w/w) crude fat, 1.5% (w/w) crude fibre and 25.5% (w/w) carbohydrates based on dry matter. The extent of biological acidification during soaking prior to fungal inoculation was inadequate to prevent growth of Bacillus cereus, and requires further optimisation. Bitter seeds were detoxified by the tempe process (approx. 70% of total cyanide was removed). However, additional improvement of the detoxification process is required to obtain a completely safe product. © 1990.
