• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.8
• /
• pp.922-929
• /
• 2007

The complete oxidation of ammonia to nitrate is a distinctive two-step process divided into the oxidation of ammonia to nitrite(nitritation) by Nitrosomonas and the oxidation of nitrite to nitrate(nitratation) by Nitrobacter. The nitrogen removal via nitrite accumulation offers several advantages such as saving costs for aeration, saving carbon source and finally reduction of sludge discharge. In this work a suspended bioreactor coupled with membrane filtration(MBR) was used to find the process conditions of nitrite build-up. The MBR enables to reach sufficient nitrifying bacteria in the bioreactor, although the autotrophic bacteria can be easily washed out due to their lower growth rate. The dissolved oxygen concentration $c'_{O2}$ and ammonia concentration $c_{NH3}$ in the reactor were varied and investigated as parameters for nitrite accumulation. As a result the higher ammonia concentration in the reactor is very effective for starting nitrite build-up and the effect was strengthened in combination with lower dissolved oxygen concentration. With lower $c'_{O2}<0.3$ $mgL^{-1}$ $O_2$ and high $c_{NH3}=6.3\sim14.9$ $mgL^{-1}$ $NH_3N$ the 74% of the nitrite accumulation was achieved. Specially, it was found that the nitrite accumulation could occur not only in biofilm reactor as many references showed but also in the membrane bioreactor carried out in this study.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.26 no.4
• /
• pp.556-562
• /
• 1997

Depletion of nitrite by lactic acid bacteria isolated from Kimchi and the effects of pH and temperature on depletion of nitrite in Lactobacillus MRS broth were investigated. Depletion of nitrite by Lactobacillus plantarum and Lactobacillus sake was low in initial stage of growth but increased during growth at 15 and 2$0^{\circ}C$. L. plantarum and L. sake depleted than 90 and 75% of nitrite(250$\mu\textrm{g}$/$m\ell$) in 1 day of growth at 25 and 3$0^{\circ}C$, respectively, but depleted almost all of nitrite in 2 days. While the effect of Leuconostoc mesenteroides (150$\mu\textrm{g}$/$m\ell$) was lower compared to Lactobacillus(250$\mu\textrm{g}$/$m\ell$). In addition, even high concentrations(600 and 900 $\mu\textrm{g}$/$m\ell$) of nitrite was depleted at 2 days of growth by L. plantarum. pH of growing broth decreased as the increase of growth time and temperature, and depletion of nitrite in- creased as the decrease of pH of growing culture. However, pH of broth related with the decrease of depletion of nitrite at 25 and 3$0^{\circ}C$, but not at 15 and 2$0^{\circ}C$. Therefore, depletion of nitrite was greatly affected by growth temperature rather than by pH.

• Journal of Animal Science and Technology
• /
• v.48 no.4
• /
• pp.563-574
• /
• 2006

This study was performed to investigate if high molecular weight(～200kDa) of chitosan can be a potential possibility to replace with the sodium nitrite in low-fat sausages. pH, proximate analysis, Hunter color values, vacuum purge, expressible moisture(EM, %), texture profile analysis(TPA), shelf-life effect were measured. No differences in physico-chemical properties were observed between controls and chitosan treatments(p>0.05). Since Hunter-a-values(redness) were reduced with the addition of chitosan as compared to the sausages containing sodium nitrite and sodium lactate, it could not be replaced by chitosan completely. However, total plate counts(TPC), thiobarbituric acid reactive substance(TBARS), volatile basis nitrogen(VBN) did not differ between chitosan treatments and controls. These results indicated that the addition of chitosan into meat products would be replaced with sodium nitrite partially, but it may not be completely replaced due to the reduced Hunter-a-values. Further research will be continuously performed to screen the natural ingredients which might have a cured pigment in meat products.

• Journal of Life Science
• /
• v.8 no.5
• /
• pp.473-478
• /
• 1998

The radical scavenging activity of the methanol extracts was in the order of doenjang〉 meju〉 soybean. The metha-nol extracts were further fractionated with dichloromethane, ethyl acetate, butanol and water in sequence. Among the solvent fractions of the methanol extracts, the ethyl acetate fraction demonstrated high levels of radical scave-nging activity. On the other hands, the nitrite scavenging activity of the methanol extrats was in the order of doen-jang〉soybean〉meju. All fractions from doenjang were exhibited the strong nitrite scavenging effect. Especially, $H_2O$, EtOAc and BuOH fractions with 6gmg/10$m\ell$ concentration exhibited much stronger nitrite scavenging effect than that of L-ascorbic acid. The ethyl acetate fraction showed remarkable antioxidant and nitrite scavenging effects compared with the other fractions obtained from soybean, meju and doenjang. The ethyl acetate fraction of doenjang was fur-ther purified by repeated chromoatograpic methods and isolated three compounds. There are identified as genistin, dai-dzein and genistein on the basis of spectral data.

• Korean Journal of Food Science and Technology
• /
• v.20 no.3
• /
• pp.453-458
• /
• 1988

This research was carried out to investigate the effects of Maillard reaction products and nondialyzable melanoidins on the nitrite-scavenging. Nitrite-scavenging reactions were done at the different pH conditions(pH 1.2, 4.2 and 6.0). Maillard reaction products and nondialyzable melanoidins, produced from the glucose-amino acids(lys., gly., arg., his.)model systems, had a great of nitrite-scavenging effects. Nitrite-scavenging effects of Maillard reaction products and nondialyzable melanoidins were also pH dependent, being higher at pH 1.2 and lower at pH 6.0. By the treatment of Maillard reaction products and nondialyzable melanoidins with sodium borohydride, nitrite-scavenging effects were remarkably decreased at pH 1.2.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.8 no.1
• /
• pp.15-20
• /
• 1979

The nitrite and nitrate levels of carrot juice at various temperature and periods were studied. The nitrite level of carrot juice at high temperature increased rapidly as the bacterial level increased. When carrot juice was held at $30^{\circ}C$, nitrite concentration began to decline after 14 hours, although there was no decrease in bacterial population, The nitrate level of carrot juice at high temperature decreased rapidly. The bacteria in carrot juice were supposed to reduce nitrates to nitrites, No increase in nitrite and no decrease in nitrate occured when bacterial growth was prevented by holding the juice at $5^{\circ}C$ or by adding potassium dehydroacetate.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.38 no.7
• /
• pp.892-901
• /
• 2009

This study confirmed depletion efficiency of nitrite when incubate lactic acid bacteria was isolated from commercial Chinese cabbage pickles (Baechu kimchi), pickled ponytail radishes (Chongkak kimchi), radish cube kimchi (Kaktugi) and pickled Wakegi (Pa kimchi) at temperatures of $15^{\circ}C$ and $25^{\circ}C$. At $15^{\circ}C$, lactic acid bacteria isolated from commercial kimchi depleted nitrite actively except Leuconostoc mesenteroides subsp. mesenteroides and Leuconostoc paramesenteroides. In particular, Leuconostoc mesenteroides subsp. dextrinicum and Leuconostoc lactis depleted nitrite by very actively without period adaptation in nitrite. Lactobacillus sake, Lactobacillus plantarum, Lactobacillus casei subsp. pseudoplantarum, and Lactobacillus coryniformis subsp. torquens depleted nitrite very actively after 1 day. L. mesenteroides subsp. mesenteroides depleted nitrite relatively actively after 2 days pass. In contrast, L. paramesenteroides displayed very low nitrite depletion ratio compared to other species. At $25^{\circ}C$, all lactic acid bacteria isolated from commercial kimchi did not need adapting period in nitrite, and depleted nitrite very actively except L. paramesenteroides. Also, all lactic acid bacteria except L. mesenteroides subsp. mesenteroides and L. paramesenteroides nitrite of more than 90% after 1 day, and L. mesenteroides subsp. mesenteroides depleted nitrite of more than 90% after 2 days. However, because L. paramesenteroides was not active even at $25^{\circ}C$, nitrite depletion efficiency was very low compared to other species. On the other hand, the same species of Lactobacilli and Leuconostocs except L. mesenteroides subsp. mesenteroides and L. paramesenteroides of other kimchi origin at $15^{\circ}C$ as well as $25^{\circ}C$ by vitality depleted nitrite very actively without statistically significant difference (p<0.05).

• 레미콘
• /
• no.1 s.74
• /
• pp.33-45
• /
• 2003

• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.1
• /
• pp.57-63
• /
• 2013

A combined process consisted of a biofilm reactor and a continuously stirred-tank reactor (CSTR) was investigated for highly loaded ammonium wastewater treatment via nitrite accumulation. To enhance ammonium oxidizing bacteria over nitrite oxidizing bacteria on the surface of carriers, the biofilm reactor was operated at temperature of $35^{\circ}C$ for more than three months but the influent ammonium (500 mg-N/L) was partially oxidized to nitrite (240 mg-N/L). As pH was increased from 7.5 to 8.0, nitrite accumulation was fully achieved due to the inhibition of nitrite oxidizing bacteria under high free ammonia concentration. The biofilm reactor performance was severely deteriorated at the hydraulic retention time of 12 hr, at which incomplete nitrification of ammonia was observed. Various solubilization methods were applied to sewage sludge for enhancing its biodegradability and the combined method, alkaline followed by ultrasonic, gave the highest solubilization efficiency (58%); the solubilized solution was used as the external carbon source for denitrification reaction in CSTR. FISH analysis showed that the dominant microorganisms on the carriers were ammonium oxidizing bacteria such as Nitrosomonas spp. and Nitrospirar spp. but low amounts of nitrite oxidizing bacteria as Nitrobacter spp. was also detected.

• Food Science of Animal Resources
• /
• v.23 no.4
• /
• pp.299-308
• /
• 2003

Quality characteristics of sausage added with green tea powder was studied to investigate the substitutive effect of green tea for nitrite. Residual nitrite, thiobarbituric acid reactive substances(TBARS) and volatile basic nitrogen(VBN) contents of 9 different sausages prepared with 3 levels of nitrite(50, 100 or 150 ppm) and 3 levels of green tea(0, 0.5 or 1％) were measured during storage at l0$^{\circ}C$ for 6 weeks or 20$^{\circ}C$ for 14 days. Proximate compositions of the sausage were not affected by the addition level of green tea or nitrite. The lightness(L value) and redness(a value) of sausage decreased, while yellowness(b value) increased, with the addition of green tea powder. Residual nitrite content was lower in sausages containing green tea when prepared with same amount of nitrite, showing the addition of green tea powder has a beneficial effect on reducing the residual nitrite content in sausage. TBARS and VBN contents were lower in sausages with nitrite and green tea than those with nitrite alone. The TBARS and VBN lowering effects of green tea were higher in sausages prepared with low level of nitrite than those prepared with high amount of nitrite. The results suggest that the addition of green tea powder may reduce the residual nitrite content of sausage, and the use of green tea may also cut down the use of nitrite in the production of pork sausage with little deterioration in preservation.