• Applied Biological Chemistry
• /
• 제49권2호
• /
• pp.158-162
• /
• 2006

두부의 저장 중 신선도를 판정 할 수 있는 신선도표시계를 제작하여 두부의 표면에 부착하여 품질변화를 측정하였다. 부패시점을 판정하기 위하여 pH, VBN, TBARS, 총균수 및 관능검사를 수행하였다. 두부의 저장 중 품질변화를 측정한 결과 신선도표시계의 반응 시점과 같은 저장 8일째에 두부는 부패초기수준에 도달하여 pH는 5.6, 총균수는 7.63 log CFU/g의 값을 나타내었다. 또한 VBN, TBARS 값도 상승하였고, 관능검사 결과도 저장 8일 이후에는 이취 및 표면에 점질물 생성 및 조직의 저하 등 가식이 불가능 하였다. 따라서 본 연구에서 사용된 신선도표시계는 두부의 저장 중 신선도를 실시간으로 나타내줌으로써 두부의 유통기한 확립 측면에서 매우 유용한 도구가 될 것으로 판단된다.

• Mass Spectrometry Letters
• /
• 제6권3호
• /
• pp.71-74
• /
• 2015

Low temperature plasma (LTP) ionization mass spectrometry (MS) is one of the widely used ambient analysis methods which allows soft-ionization and rapid analysis of samples in ambient condition with minimal or no sample preparation. One of the major advantages of LTP MS is selective analysis of low-molecular weight, volatile and low- to medium-polarity analytes in a sample. On the contrary, the selectivity for particular class of compound also implies its limitation in general analysis. One of the critical factors limiting LTP ionization efficiency is poor desorption of analytes with low volatility. In this study, a home-built LTP ionization source with Peltier heating sample stage was constructed to enhance desorption and ionization efficiencies of analytes in a sample and its performance was evaluated using standard mixture containing fatty acid ethyl esters (FAEEs). It was also used to reproduce the previous bacterial identification experiment using pattern-recognition for FAEEs. Our result indicates, however, that the bacterial differentiation from FAEE pattern recognition using LTP ionization MS still has many limitations.

• 한국축산식품학회지
• /
• 제23권4호
• /
• pp.285-291
• /
• 2003

도체등급과 쑥 분말의 첨가가 소시지의 저장 안정성에 미치는 영향에 대한 연구를 위하여 B 등급육과 E 등급육(경산 모돈육)에 쑥 분말을 0.3% 첨가한 것과 첨가하지 않은 소시지를 제조하고, 4$\pm$1$^{\circ}C$에서 8주 동안 저장하면서 pH, 휘발성 염기태질소(VBN) 함량, TBARS 값, 일반세균수 및 아질산염 잔류량에 대하여 검토하였다. 소시지의 pH는 B 등급육으로 제조한 소시지가 낮고, 냉장 중 쑥 분말을 첨가한 소시지가 현저한 차이는 아니었지만 비교적 낮았다. VBN 함량은 원료육과 쑥 분말 첨가에 의한 현저한 차이가 없었다. TBARS 값은 원료육의 등급에 따라 유의적인 차이를 나타내지 않았으며, 냉장 중 쑥 분말을 첨가한 소시지가 낮게 나타났다. 일반 세균수는 원료육의 등급에 의한 현저한 차이를 보이지 않았고, 냉장 중 쑥 분말을 첨가한 소시지가 적게 나타났다. 아질산염 잔류량은 원료육에 따른 차이를 보이지 않았고, 냉장 중 쑥 분말 첨가에 의해 감소되었다.

• 한국식품조리과학회지
• /
• 제33권3호
• /
• pp.256-263
• /
• 2017

Purpose: Essential oils are secondary metabolites of herbs and have antibacterial activities against foodborne pathogens. However, their applications for food protection are limited due to the hydrophobic and volatile natures of essential oils. Methods: In this study, essential oil nanoemulsions of rosemary and lavender were formulated with non-ionic surfactant Tween 80 and water using ultrasonic emulsification, and their antibacterial effects were determined. Results: The antibacterial activities of nanoemulsions were evaluated against 12 strains of 10 bacterial species, and significant antibacterial effects were observed against four Gram-positive and four Gram-negative bacteria but not against Streptococcus mutans and Shigella sonnei. In the disc diffusion test, the diameter of the inhibition zone proportionally increased with the concentration of nanoemulsions. Using cell turbidity measurement, minimum bactericidal concentration (MBC) of the nanoemulsions, which is the lowest concentration reducing viability of the initial bacterial inoculum by ${\geq}99.9%$, was significantly higher than the minimum inhibitory concentration (MIC) of the nanoemulsions. The largest bactericidal effects of lavender and rosemary essential oil nanoemulsions were observed against S. enterica and S. aureus, respectively. Conclusion: Nanoemulsion technique could improve antibacterial activity of essential oil nanoemulsions by increasing the solubility and stability of essential oils. Our findings shed light on the potential use of essential oil nanoemulsions as an alternative to chemical sanitizers in food protection.

• Mycobiology
• /
• 제46권1호
• /
• pp.52-63
• /
• 2018

In our previous studies, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15 have been shown to be antagonistic to Aspergillus flavus in stored rice grains. In this study, the biocontrol activities of these strains were evaluated against Aspergillus candidus, Aspergillus fumigatus, Penicillium fellutanum, and Penicillium islandicum, which are predominant in stored rice grains. In vitro and in vivo antifungal activities of the bacterial strains were evaluated against the fungi on media and rice grains, respectively. The antifungal activities of the volatiles produced by the strains against fungal development and population were also tested using I-plates. In in vitro tests, the strains produced secondary metabolites capable of reducing conidial germination, germ-tube elongation, and mycelial growth of all the tested fungi. In in vivo tests, the strains significantly inhibited the fungal growth in rice grains. Additionally, in I-plate tests, strains KU143 and AS15 produced volatiles that significantly inhibited not only mycelial growth, sporulation, and conidial germination of the fungi on media but also fungal populations on rice grains. GC-MS analysis of the volatiles by strains KU143 and AS15 identified 12 and 17 compounds, respectively. Among these, the antifungal compound, 5-methyl-2-phenyl-1H-indole, was produced by strain KU143 and the antimicrobial compounds, 2-butyl 1-octanal, dimethyl disulfide, 2-isopropyl-5-methyl-1-heptanol, and 4-trifluoroacetoxyhexadecane, were produced by strain AS15. These results suggest that the tested strains producing extracellular metabolites and/or volatiles may have a broad spectrum of antifungal activities against the grain fungi. In particular, B. megaterium KU143 and P. protegens AS15 may be potential biocontrol agents against Aspergillus and Penicillium spp. during rice grain storage.

• Animal Bioscience
• /
• 제34권4호
• /
• pp.613-620
• /
• 2021

Objective: This study aimed at studying the potential use of Flemingia (Flemingia macrophylla) as a protein source fodder to improve nutrients digestibility and ruminal fermentation efficiency in beef cattle. Methods: Four, Thai native beef cattle were randomly assigned in a 4×4 Latin square design. Four levels of Flemingia hay meal (FHM) were used to replace soybean meal (SBM) in the concentrate mixtures in four dietary treatments replacing levels at 0%, 30%, 60%, and 100% of SBM. Results: The experimental findings revealed that replacements did not effect on intake of rice straw, concentrate and total dry matter (DM) intake (p>0.05). However, the apparent digestibilities of DM, organic matter, crude protein, acid detergent fiber, and neutral detergent fiber were linearly increased up to 100% replacement levels. Moreover, the production of total volatile fatty acids, and propionate concentration were enhanced (p<0.05) whereas the concentration of acetate was reduced in all replacement groups. Consequently, the CH4 production was significantly lower when increasing levels of FHM for SBM (p<0.05). Furthermore, rumen bacterial population was additionally increased (p<0.05) while protozoal population was clearly decreased (p<0.05) in all replacement groups up to 100%. In addition, microbial nitrogen supply and efficiency of microbial nitrogen synthesis were enhanced (p<0.05), as affected by FHM replacements. Conclusion: The findings under this experiment suggest that 100% FHM replacement in concentrate mixture enhanced rumen fermentation efficiency, nutrients digestibilities, bacterial population, microbial protein synthesis, and subsequently reduced CH4 production in beef cattle fed on rice straw.

• 한국식품저장유통학회지
• /
• 제17권1호
• /
• pp.23-29
• /
• 2010

본 연구에서는 식초, 주정 및 비타민 C 등의 첨가물을 넣어 제조한 생강다대기를 튜브용 용기에 담아 $10^{\circ}C,\;20^{\circ}C,\;30^{\circ}C$에서 각각 보관하면서 저장기간별로 미생물 수, 색도, 향기성분변화, 유리당, 유리아미노산 및 지방산의 특성변화를 살펴보았다. 생강다대기의 일반세균수는 저장기간 동안 미생물 수의 변화가 거의 없었고, 곰팡이의 경우 생강다대기에서 존재하지 않는 것을 확인하였다. 효모의 경우 저장초기 $5{\times}10^1$ CFU/g의 효모가 존재하였으나, 저장 2주경과 후부터 존재하지 않는 것을 확인하였다. 생강다대기의 저장 중 색도를 측정한 결과, 저장기간이 경과할수록 그리고 저장온도가 높을수록 색깔의 변화가 증가하는 것을 볼 수 있었다. 생강다대기의 저장온도에 따른 향기성분은 저장초기와 비교하여 17주 경과 후 생강다대기의 향기성분의 총 함량이 다소 감소하는 경향을 나타내었다. 생강다대기 중의 유리당은 저장기간이 경과함에 따라서 sucrose 함량은 감소하고, fructose 및 glucose 함량은 증가하였다가 감소하는 경향을 나타내었다. 유리아미노산의 경우 저장온도가 높을수록 약간 감소하는 경향을 나타내었으며, 주요 아미노산 성분으로 glutamine, valine, alanine, asparagine, tyrosine 및 leucine이 검출되었다. 생강다대기의 지방산의 변화를 살펴본 결과 초기치 지방산 함량에 비하여 조금 증가한 결과를 나타내었고, 지방산의 조성으로 불포화 지방산보다 포화지방산의 비율이 높게 나타났다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제19권3호
• /
• pp.376-380
• /
• 2006

An experiment was conducted to study the effect of temperature and pH on in vitro nutrient degradability, volatile fatty acid profile and methane production. The fermenter used was the semi-continuous system, known as the rumen simulation technique (RUSITEC). Sixteen cylinders were used at one time with a volume of 800 ml, the dilution rate was set at 3.5%/hour, the infused buffer being McDougall's artificial saliva. Basal diet (9.6 g DM) used in RUSITEC consisted of (DM) 6.40 g Timothy hay, 1.86 g crushed corn and 1.34 g soybean meal. The food for the fermentation vessel was provided in nylon bags, which were gently agitated in the liquid phase. The experiment lasted for 17 d with all the samples taken during the last 5 d. Treatments were allocated at random to four vessels each and were (1) two temperature levels of $39^{\circ}C$ and $41^{\circ}C$ (2) two pH levels of 6.0 and 7.0. The total diet contained ($g\;kg^{-1}$ DM) 957 OM, 115 CP and $167MJ\;kg^{-1}$ (DM) GE. Although increase in temperature from $39^{\circ}C$ to $41^{\circ}C$ reduced degradation of major nutrients in vitro, it was non-significant. Interaction effect of temperature with pH also reflected a similar trend. However, pH showed a significant (p<0.05) negative effect on the degradability of all the nutrients in vitro. Altering the in vitro pH from 7 to 6 caused marked reduction in DMD from 60.2 to 41.8, CPD from 76.3 to 55.3 and GED from 55.3 to 35.1, respectively. Low pH (6) depressed total VFA production (61.9 vs. 34.9 mM) as well as acetate to propionate ratio in vitro (from 2.0 to 1.5) when compared to pH 7. Compared to pH 7, total gas production decreased from 1,841 ml to 1,148 ml at pH 6, $CO_2$ and $CH_4$ production also reduced from 639 to 260 ml and 138 to 45 ml, respectively. This study supported the premise that pH is one of the principal factors affecting the microbial production of volatile fatty acids and gas. Regulating the ruminal pH to increase bacterial activity may be one of the methods to optimize VFA production, reduce methane and, possibly, improve animal performance.

• Journal of the Korean Wood Science and Technology
• /
• 제42권6호
• /
• pp.747-757
• /
• 2014

건축재료와 생활용품으로부터 방출되는 실내공기 오염물질들로 인한 피해가 증가하고 있는 현시점에서 친환경 제품에 대한 관심이 높아지고 있다. 이러한 관심 속에 피톤치드에 대한 효능이 알려지면서 다양한 방법으로 사용되고 있다. 피톤치드를 다량 함유한 편백잎 증류추출수의 가습시 발생하는 휘발성유기화합물의 방출특성을 GC-MS를 이용하여 그 효과를 조사하였다. 편백잎추출수 가습시 115종의 화합물이 검출되었다. 검출된 화합물들은 aromatic compound, terpenoid, alkane, ketone, ester, aldehyde, alcohol, acid, miscellaneous compound류로 분류하였으며 aromatic compound류(13종, 38%)와 terpenoid류(23종, 33%) 화합물이 다른 화합물류에 비해 높은 비율로 검출되었다. Aromatic compound류 경우 편백잎추출수에 의한 추가 화합물은 검출되지 않아 그 영향이 없는 것으로 판단되며, terpenoid류 경우 편백잎추출수 가습시 10% 정도 증가하였고 7종의 화합물이 추가로 검출되었다. 편백잎추출수 가습시 방출된 terpenoid류 화합물들은 항균, 방충, 방부 효력뿐만 아니라 항고혈압성과 항암에 효과가 있는 것으로 알려져 있어 건강에 도움을 줄 것으로 판단된다.

• 한국식품영양과학회지
• /
• 제38권11호
• /
• pp.1564-1570
• /
• 2009

김치와 각각의 부재료들의 향기 성분을 비교하기 위하여 GC/MS로 정성 분석한 결과, 김치의 향기 성분은 sulfide 계열의 황 화합물과 유기산, 알코올류 등으로 나타났고, 김치의 냄새를 구성하는 물질들은 김치의 냄새를 각각의 부재료에서 검출된 향기 성분들로부터 유래한 것으로 확인되었다. 김치 특유의 이취를 저감시키기 위하여 김치의 부재료인 마늘, 생강, 양파 및 파를 각각 5 mm의 길이와 0.3 mm의 두께로 세절하고 100$^{\circ}C$ 에서 2분간 데친 후, 정수된 물 4$^{\circ}C$ 에서 12시간 동안 침지처리 하였다. 부재료 침지처리가 김치의 군덕내(moldy odor)와 신내(sour odor)에 미치는 영향을 관능검사로 평가한 결과, 세절침지처리김치에서 일반김치에 비하여 신내와 군덕내가 크게 감소한 것으로 나타났다. 또한 부재료의 침지처리가 숙성 중 김치에서 pH, 산도, 유산균수에 영향을 미치는 것으로 나타났다.