The effect of ripening temperature, pH and salinity on the formation of N-nitrosamine (NA) during Kimchi fermentation and in vitro was studied, respectively. During Kimchi fermentation for six weeks at cold storage temperature (4℃) and room temperature (16 ±2℃), the contents of nitrite and dimethylamine (DMA) showed variation at room temperature but no variation at cold storage temperature. The maximum generation of nitrosodimethylamine (NDMA) resulted low content (2.69 ug/kg) at cold storage temperature but started to increase after one week fermentation and reached to the 18-fold higher generation (49.6 ug/kg) at room temperature. During Kimchi fermentation, no correlation was observed between the variation of nitrite and DMA content and the generation of NDMA. However, pH showed effective relation to NDMA generation such as the highest NDMA generation was obtained at lowest pH 4. During in vitro test, higher temperature and lower pH resulted more NDMA generation and generation amount was affected more by pH. Also, the salinity of Kimchi provided inhibitory effects on the formation of NDMA. NDMA was produced 5.86 ug/kg at normal salinity (2.5%) but 90.9 ug/kg at lower salinity (15%) after three week. The higher salinity showed lower formation of NDMA in vitro test, too.

Polyvinyl alcohol[PVA] is useful for the production of water-soluble packaging, paper, textile sizes. PVA and Chitosan are known as biodegradable polymers. PVA/chitosan blend films were prepared by solution blends method in the weight ratio of chitosan for the purpose of useful biodegradable films. Thermal and mechanical properties of PVA/chitosan blend films such as DSC, impact strength, tensile strength and morphology by SEM were determined. As a result, The ratio of 10.0wt% PVA/chitosan blend films were similar to PVA. Blend films were completely degraded pH 4.0 better than 7.0, 10.0 in the buffer solution. Also, Blend films were rapidly degraded enzyme(β-glucosidase) solution better than pH solution by Enzymolysis.

Effects of benzoate (0-0.6 g/l and sorbate (0-2.0 g/l) on the growth of Escherichia coli O157:H7 in tryptic soy broth at various pH levels (4-8) and temperatures (4℃, 37℃) were investigated. Benzoate and sorbate were inhibited the growth of E. coli 0157:H7 up to 12 hours cultivation at 4℃, and 2.0 g/l sorbate was only inhibited during 48 hours cultivation at 37℃. Among the pH levels tested, pH 4 showed significant inhibitory effect against the E. coli O157:H7 on 4℃ and at 37℃, respectively. When used in combination 0.2 g/l benzoate and sorbate were completely inhibited the growth of E. coli O157:H7 on pH 4 and at 37℃. While on pH 5 at 4℃, all of the concentration tested did not exert any inhibitory effect. The combined effects were retarded more than single treatment of E. coli O157:H7.

겉뿌림 산지초지의 조성, 수량, 식생 및 목초품종등에 미치는 3요소(N--O: 0-0-0; 0-10-10; 6-15-15; 12-20-20; 24-25-20 kg/10a/year)와 소석회(0, 250kg/10g; 조성시만 시용)의 시용효과를 구명하는 10년간 시험후, 별도로 토심별 토양의 화학성(I보; pH, OM, T-N, 유효 , 흡수계수, 석회소요량. II보: 치환성 Ca, Mg, K, Na 및 CEC, 염기포화도, 토양보존)을 조사하여 검토하

Dendrobium kingianum의 유묘증식(幼苗增殖)을 위한 기초자료(基礎資料)를 얻고자 발아(發芽)에 미치는 기본(基本) 배지(培地)의 영향(影響)과 유묘생장(幼苗生長)에 미치는 hyponex의 종류별농도(種類別濃度), auxin 농도(濃度), 당(糖), 한천(寒天) 및 pH의 영향(影響)을 알고자 실험(實驗)한 결과(結果)를 요약(要約)하면 다음과 같다. 종자(種子)의 발아(發芽)는 hyponex +peptone 가 함유된 배지(培地)에서 가장 양호(良好)하였으며 유묘(幼苗)의 증식(增殖) 및 생장(生長)은 hyponex +peptone 가 함유된 배지(培地)에 IBA , sucrose , agar 첨가배지(添加培地)에서 multiple shoot가 형성(形成)되었으며 유묘(幼苗)의 생장(生長)을 촉진(促進)시키기 위해서는 auxin이 첨가(添加)되지 않은 배지(培地)에 sucrose 한천(寒天) 및 pH는 5.0이 가장 적합(適合)하였다.

This study aimed to investigate the effect of amino acid additives to weaned piglet diets on the pH and volatile fatty acids of pig slurries. A total of 135 weaned 22 -day-old piglets (Yorkshire x Landrace x Duroc) were used in this 56-d study. The three dietary treatments were as follows: (1) Control as a basal diet, (2) 1% amino acid additive and (3) 2% amino acid additive. Both pH and acetic acid values at 71 and 78 days were significantly different in all treatment groups (p<0.05). In addition, significant differences in propionic acid values were observed among treatment groups at 64 and 78 days (p<0.05). However, pH, acetic acid, and propionic acid values did not differ between 1% and 2% amino acid treatment groups. In conclusion, adding 1% and 2% amino acid to weaned piglet diets reduced the pH, acetic acid and propionic acid contents of pig slurries by acting as a probiotic. This may help formulate increase management strategies for improving the pig housing environment.

The effects of essential oils on pH, pathogens, and volatile fatty acids (VFA) in two poultry litters were investigated through a lab study. Essential oil-added poultry litters were randomly divided to two groups: control (200 g poultry litter) and Treatment (50 g thymol/Briefly, 200 g broiler litter was treated with or without 50 g thymol (Control and T1, respectively; 1 groups) and 200 g duck litter was treated with or without 50 g carvacrol (Control and T2, respectively; 2 group). Adding thymol to broiler litter increased the pH, reduced pathogens, and did not affect VFA. Interestingly, adding carvacrol slightly reduced the pH of duck litter, but had no significant effect on reducing pathogens and VFA. This difference is probably because the essential oil used and the properties of the two litters are different. In addition, pH was thought to control the odor generated from the litter, but this has not been proven. Further field studies should focus on clarifying this point.

가죽 제조 산업의 현황을 살펴보면 가공에 사용되는 원료피의 50%가 폐기물로 발생되어 진다. 가죽 원료에서 많은 부분이 폐기물로 발생하기 때문에 해당 공정의 폐기물 처리와 함께 자원으로서의 활용적 측면이 함께 고려되어야한다. 하지만 현재 대부분의 피혁폐기물은 주로 매립과 소각 방법으로 처리되고 있어 보다 지속가능하고 환경 친화적인 처리 방법이 요구되고 있는 실정이다. 본 연구에 사용된 피혁폐기물은 가죽 제조 공정 중 탈모공정(Liming) 후에 발생하는 Pelt scrap으로, 주성분이 지질과 단백질로 구성되어 있어 혐기성 소화를 통한 처리 시 효율적인 메탄 생성 기질로 사용될 수 있다. 다만, 피혁폐기물은 pH와 C/N 비가 높아 혐기성 소화 시 메탄 생성 과정에 저해를 줄 수 있어 이에 대한 조절이 필요하다. 일반적으로 피혁폐기물의 pH는 12 부근으로 알려져 있으며, 혐기성소화 공정에서 기질의 pH가 6이하 또는 8.5이상인 경우 메탄 생성에 영향을 줄 수 있다. 이에 효율적인 피혁폐기물 처리와 메탄가스 생산을 위해서는 기질의 pH 조절이 필요하다. 본 연구에서는 피혁폐기물의 높은 pH를 혐기성소화에 알맞은 중성으로 조절해주기 위해 pH가 낮으면서 생분해도가 높은 음폐수를 통합 기질로 사용해 혐기성소화를 실시하였다. 실험에 사용된 피혁폐기물과 음폐수의 pH는 각각 12.4와 4.2였으며, 이를 VS기준 0.13:0.87의 비율로 혼합하여 혼합기질의 pH를 7.7로 만들었다. 250mL serum bottle에 하수슬러지 100mL를 식종하고 기질 1g VS를 주입하였고 35℃, 150rpm으로 유지되는 항온교반기에서 진행하였다. 기질 pH 조절에 의한 소화 성능 확인을 위해 피혁폐기물과 음폐수 단독소화를 실시하고, 이를 pH 7로 조절한 통합소화 조건과 비교하였다. 이때 소화성능은 유기물 감량과 바이오가스 생산량 및 메탄함량을 통해 평가하였다. 실험 결과, 단독 소화와 비교해 기질의 pH를 조절해 통합소화에서 바이오가스 생산량과 메탄 함량이 증대되는 경향을 보였다. 결론적으로 혐기성소화 시 기질 혼합을 통한 중성 pH 조성은 바이오가스 생산량과 메탄 함량의 증가에 영향을 주는 것으로 판단된다.

The objective of this study was to evaluate the effect of applying alum (aluminum sulfate) and aluminum chloride on pH and pathogen populations of Hanwoo manure. A total of 36 steers (8 months old and averaging 300 kg in weight) were used in this trial and allotted to 9 pens (3 replication pens per group with 4 steers per experimental unit, 5 x 8 m). Chemical additives were applied as a top dressing with garden rake to a depth of 1 cm of manure with wood shavings in each treatment. The chemical amendments were control (without chemical amendments), 50 g of alum and 50 g of aluminum chloride/kg of Hanwoo manure. The experiment was carried out for 4 weeks. Adding alum and aluminum chloride to Hanwoo manure reduced (P < 0.05) pH compared to untreated controls during the 4-wk period. Both levels of the alum and aluminum chloride treatments tested decreased (P < 0.05) Escherichia coli and Salmonella enterica populations in Hanwoo manure at 2 and 4 weeks. It appears that the reduction in pathogen populations was primarily associated with the lower manure pH. If more strict environmental regulations are put into effect regarding pathogen populations from Hanwoo facilities, treating Hanwoo manure with alum and aluminum chloride may be a good management practice.

Batch cultivations were performed to evaluate the influences of the initial pH condition on mesophilic and thermophilic acidogenic fermentation with food waste recycling wastewater. In both conditions of mesophilic and thermophilic fermentation, TVFAs production rates were maximized at the initial pH 7 condition as 0.15 and 0.23 g TVFAs/L·hr, respectively. And pH was also maintained stably between 6 and 7 during 72hr acidogenic cultivation at both conditions. However, predominant VFA components were different according to reaction temperature conditions. In mesophilic condition, propionic acid which has low conversion efficiency to methane was accumulated up to 1,348 mg/L while acetic and butyric acid were predominant in thermophilic condition. Therefore, thermophilic acidogenic fermentation was superior for the effective VFAs production than mesophilic condition. From the DGGE analysis, the band patterns were different according to the initial pH conditions but the correlations of the each band were increased in similar pH conditions. These results mean that microbial communities were certainly affected by the initial pH condition. Consequently, the adjustment of the initial pH to neutral region and thermophilic operation are needed to enhance acidogenic fermentation of food waste recycling wastewater.

오염 원인 물질의 해양 내 거동에 대한 파악은 환경 변화에 따른 부영양화 등 해양 수질 오염에 대한 예측 및 대응 방안 선정을 위한 전제 조건이다. 본 연구에서는 부영양화 원인 물질인 인의 해양퇴적물에서 해수로의 용출 특성을 조사하였다. 검토된 환경 조건은 pH 7-9, 온도 10-20℃, 용존 산소 농도(dissolved oxygen, DO) 0.7-7.0 mg/L 였다. 생물학적 요인을 배제한 조건에서 회분식 실험을 통해 구해진인 용출 자료는 1차 반응식으로 해석되었으며, 환경 조건의 영향은 통계학적 방법을 통해 정량화 되었다. 해양 퇴적물로부터 해수로의 인 용출은 pH와 온도가 높고 DO가 낮을수록 증가하였다. 1차 반응 평형 농도 기준으로 검토된 범위의 pH 증가, 온도 증가, DO 감소는 각각 인용출을 2-3배 증가시켰다.

The goals of this study were conducted to investigate the effects of applying liquid aluminum chloride (AlCl3) to rice hulls on pH and soluble reactive P (SRP). A total of 800 broiler chicks (4 treatments × 4 replicates × 50 birds) were housed into 16 floor pens in a single house for 5 weeks. The treatments were divided into 4 groups: control, 100 g of liquid AlCl3/kg of rice hulls, 200 g of liquid AlCl3/kg of rice hulls, and 300 g of liquid AlCl3/kg of rice hulls. Liquid AlCl3 was sprayed on the rice hulls surface at a rate of 100 g, 200 g, and 300 g liquid AlCl3 per kg rice hull. pH values and SRP contents were significantly decreased (P<0.05) with the increased liquid AlCl3 levels in comparison with control. However, no significant differences in SRP contents were observed among all treatments at 3 and 4 weeks. Applying 100 g, 200 g, and 300 g liquid AlCl3 to rice hulls reduced SRP contents by 18, 25, and 52% for 5 weeks, respectively, compared with the controls. In conclusion, these results suggest that using liquid AlCl3 on rice hulls should be promising for reducing water contamination and resulted in a reduction in SRP contents, which reduced pH.

인위적인 토양 pH 변화가 식물에 미치는 영향과 식물의 생화학적 방어반응을 조사하고자 황산용액을 첨가하여 산성화시킨 토양(pH 5.3, 4.5, 3.9, 3.5)에 만수국을 이용하여 실험을 수행하였다. 토양 산성화에 의해 MDA 함량이 크게 증가되었다. 토양의 H+ 부하량 증가에 따라 산화형인 DHA 및 GSSG의 함량이 크게 증가되었다. 항산화 효소의 활성도 토양의 H+ 부하량의 증가에 따라 증가하는 것으로 나타났다.

바위취의 토양산도별 생육특성을 보면 초장, 엽수, 엽장, 엽폭 그리고 초폭에 있어서 모두 pH 4.5에서 생육량이 많았으며 pH가 높을수록 생육량이 현저하게 떨어지는 경향으로 통계적인 유의성이 인정되었다. 따라서 바위취 분화생산시 경량 배양토의 토양산도를 pH4.5~5.0 정도로 맞추어 주는 것이 pH 6.0보다 초기 활착이 빠르고 생육이 양호하며 균일성이 높아지는 것으로 나타났다.

기린초의 토양 pH별 생육특성을 보면 pH가 낮을수록 생육초기부터 후기까지 초장, 엽수, 분지수 등의 생육이 좋았으며 특히 초장과 분지수에서는 pH처리에 따라 통계적인 유의성이 인정되었다. 따라서 기린초 재배시에는 토양 pH를 4.5~5.0정도로 맞추어 주는 것이 pH 6.0보다 초기 활착이 빠르고 생육이 양호하며 균일성이 높아지는 것으로 나타났다.

The effects of pH (5, 7 and 9) and ionic strength of different salts on the flocculation characteristics of humic acid by inorganic (alum, polyaluminum chloride (PAC) with degree of neutralization, r=(OH/Al) of 1.7) and organic (cationic polyelectrolyte) coagulants, have been examined using a simple continuous optical technique, coupled with measurements of zeta potential. The results are compared mainly by the mechanisms of its destabilization and subsequent removal. The destabilization and subsequent removal of humic acid by PAC and cationic polyelectrolyte occur by a simple charge neutralization, regardless of pH of the solution. However, the mechanism of those by alum is greatly dependent on pH and coagulant dosage, i.e., both mechanisms of charge neutralization at lower dosages and sweep flocculation at higher dosages at pH 5, by sweep flocculation mechanism at pH 7, and little flocculation because of electrostatic repulsion between negatively charged humic acid and aluminum species at pH 9. The ionic strength also affects those greatly, mainly based on the charge of salts, and so is more evident for the salts of highly charged cationic species, such as CaCl2 and MgCl2. However, it is found that the salts have no effect on those at the optimum dosage for alum acting by the mechanism of sweep flocculation at pH 7, regardless of their charge.