• Title/Summary/Keyword: off-flavor

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Quality Changes of Yoghurt Added with Microencapsulated Iron during Storage (미세피복된 철분을 첨가한 요구르트의 저장 중 품질 변화)

  • 김윤지;윤칠석
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.28 no.3
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    • pp.542-546
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    • 1999
  • Uncoated, ethyl cellulose(EC) coated or methacrylic acid copolymer(MAC) coated ferrous sulfate was added to the yoghurt made from whole milk powder and quality changes of those yoghurt were observed. Among treatments uncoated ferrous sulfate added yoghurt showed the lowest quality in the view of pH, total acidity, total counts of lactic acid bacteria, and sensory characteristics. Quality change of MAC comparing to control was lower than that of EC. MAC and EC showed higher TBA value than no iron added or uncoated iron added one during storage. From sensory evaluation, MAC was not signif icantly different from control in color and off flavor after one day storage(p>0.05), however significant difference was observed in off flavor after 7 day storage(p<0.05). From above results, MAC coated ferrous sulfate added yoghurt showed better quality than uncoated or EC coated ferrous sulfate added one during storage.

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Comparison of Three Radiation Sources on Quality Properties of Three Dried Condiments (건조 향신료 3종에 대한 방사선종별 조사효과 비교)

  • Park, Kyung-Sook
    • Journal of Radiation Industry
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    • v.8 no.2
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    • pp.83-88
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    • 2014
  • Application of X-ray irradiation of dried condiments was studied using commercially prepared dried garlic, onion and welsh onion flakes as model samples. Total load of aerobic microbes (TAM), color differences, and generation of off-flavor were quantified for samples individually irradiated with gamma rays, electrons, or X-rays. TAM load was decreased by irradiation in a dose-dependent manner. The three types of radiation did not differ in the extent of TAM reduction (P>0.05). The samples did not differ in color. Off-flavor was detected from 6 kGy-irradiated samples, regardless of radiation sources. The results indicated that X-ray irradiation could be used for irradiation of dried condiments with the same effects as gamma rays and an electron beam.

Effect of Deodorizing Temperature on Physicochemical Characteristics in Corn Oil IV. Effect of Deodorizing Temperature on Volatile Flavor Component Composition in Corn Oil (탈취온도가 옥수수기름의 이화학적 특성에 미치는 영향 제4보, 탈취온도가 옥수수기름의 휘발성 냄새성분 변화에 미치는 영향)

  • 이근보;한명규;이미숙
    • The Korean Journal of Food And Nutrition
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    • v.11 no.3
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    • pp.272-277
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    • 1998
  • We carried out separation and guantitation of flavor components by GC about essential oils extracted from deodorized corn oil at the different deodorizing temperature. Flavor components were detected total 16 kinds included aldehydes of 8 kinds, major components were propane, pentane, hexanal etc. These major components content was about 70~75% of the total flavor components. According to rise of deodorizing temperature, both ethane and aldehydes of 8 kinds content were in proportion to increase, but propane, pentane, hexane, octan, pentyl furan content were decreased by contraries, respectively. On the other hand, total flavor component content was appeared the lowest level at 245$^{\circ}C$ treating group, aldehydes content was in proportion to increase according to rise of deodorizing temperature. These phenomenons consider that the undesirable reactions such as partial auto-oxidation, degradation, polymerization and hydrolysis etc. by effecting factors of stripping steam and vacuum degree. Conclusively, deodorizing temperature under high temperature was undesirable for the minimization of off-flavor materials.

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Relationship between the Production of Fermentational Off-flavor and Presence of Microbial Endophytes in Bloody Watermelon (수박의 이상 발효(피수박)와 내생세균의 존재와의 연관성)

  • Choi, Jae-Eul;Choi, Chun-Hwan;Ryuk, Jln-Ah;An, Gil-Hwan;Hwang, Yong-Soo
    • Research in Plant Disease
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    • v.10 no.4
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    • pp.285-289
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    • 2004
  • The bloody watermelon exhibiting dark red and fermentation off-flavor results in a great economic loss. As an effort to clarify the cause of the bloody watermelon, relationship between the fermentational off-flavor and the presence of endophytic bacteria was studied. The number of endophytes was 2.2-37.0 ${\times}10^3$ cfu/g fw (fresh weight) in normal watermelons, compared to 1.26-1.75 ${\times}10^6$ cfu/g fw in bloody ones. Seventeen bacteria among 56 isolates from bloody watermelons could induce bloody watermelons. The bacteria responsible for bloody watermelons were mainly Gram negative: aerobic Pseudomonas spp and some anaerobic bacteria. The results in this study strongly suggested that the bloody watermelons were produced by abnormal fermentation and growth of endophytic Gram negative bacteria.

A study on shelf life of prepackaged retail-ready Korean native black pork belly and shoulder butt slices during refrigerated display

  • Hoa, Van-Ba;Seol, Kuk-Hwan;Kang, Sun-Moon;Kim, Yun-Seok;Cho, Soo-Hyun
    • Animal Bioscience
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    • v.34 no.12
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    • pp.2012-2022
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    • 2021
  • Objective: In most retail centers, primal pork cuts for sale are usually prepared into retail-ready slices and overwrapped with air-permeable plastic film. Also, meat of Korean native black pig (KNP) is reputed for its superior quality, however, its shelf life during retail display has not been studied. Thus, the objective of this study was to evaluate shelf life of prepackaged retail-ready KNP belly and shoulder butt slices during refrigerated display. Methods: Bellies and shoulder butt obtained at 24 h post-mortem from finishing KNP were used. Each belly or shoulder butt was manually cut into 1.5 cm-thick slices. The slices in each cut type were randomly taken and placed on white foam tray (2 slices/tray) overwrapped with polyvinyl chloride film. The retail-ready packages were then placed in a retail display cabinet at 4℃. Shelf life and sensory quality of the samples were evaluated on day 1, 3, 6, 9, 12, and 15 of display. Results: The shoulder butt reached the upper limit (20 mg/100 g) of volatile basic nitrogen for fresh meat after 9 days while, the belly remained within this limit throughout the display time (15 days). Both the cuts reached a thiobarbituric acid reactive substances level of above 0.5 mg malondialdehyde/kg after 9 days. The a* (redness) values remained unchanged during first 9 days in both cuts (p>0.05). After 9 days, off-flavor was not found in either cut, but higher off-flavor intensity was found in shoulder butt after 12 days. The shoulder butt was unacceptable for overall eating quality after 12 days while, belly still was acceptable after 12 days. Conclusion: The belly showed a longer shelf life compared to the shoulder butt, and a shelf life of 9 and 12 days is recommended for the prepackaged retail-ready KNP shoulder butt and belly slices, respectively.

Effects of Lipolysis and Fatty Acid Composition on Off-flavor in Goat Milk (산양유의 지방분해 특성과 지방산 조성이 산양유 이취에 미치는 영향)

  • Lim, Y.S.;Ham, J.S.;Jeong, S.G.;Ahn, J.N.;Choi, S.H.
    • Journal of Animal Science and Technology
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    • v.50 no.1
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    • pp.111-120
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    • 2008
  • The average milk fat content in goat milk was 3.88% on yearly basis. The milk fat content of 3.8% during summer season was lower than 4.2% during winter season. Total solid content increased in proportion to milk fat. When goat milk was stored at 4℃ for 24 hr, short-chain FFA(C4:0~C10:0) and medium- and long-chain FFA(C12:0~C18:1) increased about 106% and 203%, respectively. Induced lipolysis of goat milk by homogenization increased short-chain FFA and medium- and long-chain FFA by 22% and 199%. When goat milk was treated with calf lipase, there was increase of short-chain FFA by 9 times greater than increase of medium- and long-chain FFA by 5.6 times. Treatment with lipases from Candida rugosa and Pseudomonas fluorescens resulted in increase of medium- and long-chain FFA by 34 and 162 times, respectively, which was greater than increase of short-chain FFA by 6 and 14 times, respectively. Lipolysis in goat milk stored at 4℃ for 24 hr was correlated with LPL activity in goat milk(r=0.5635). Off-flavor of goat milk was correlated with LPL activity(r=0.5777). Milk fat content was negatively correlated with LPL activity(r=-0.4627). Palmitic acid content in goat milk was correlated with off-flavor(r=0.7226).

Volatile Compounds in the Oxidation of Unsaturated Fatty Acids Caused in Off-flavor of Porcine Liver by HS-SPME (Headspace solid-phase microextraction(HS-SPME)를 이용한 간의 비린내불쾌취에 기인하는 불포화지방산 산화생성물의 휘발성성분)

  • Im, Sung-Im;Choi, Sung-Hee
    • Korean Journal of Food Science and Technology
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    • v.35 no.3
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    • pp.359-365
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    • 2003
  • Headspace solid-phase microextraction(HS-SPME) was used to isolate the off-flavor volatile compounds, which are formed during the oxidation of porcine liver and unsaturated fatty acids in porcine liver induced by iron. Three fibers for HS-SPME method development were tested, and the polydimethylsiloxane/divinylbenzene(PDMS/DVB) fiber was selected as providing the best detection of analyzed compounds. In the oxidized arachidonic acid, the major compounds identified were hexanal, 1-octen-3-one(metallic), (Z)-4-heptenal, (E)-2-octenal, 1-octen-3-ol(mushroom), (Z)-2-nonenal (cardboard-like), and (E,E)-2,4-decadienal(fatty, oily). In the oxidized linolenic acid, the major ones were (E,E)-2,4-heptadienal(fishy), (E,E)-3,5-octadien-2-one and (E,Z)-2,6-nonadienal. Moreover, those of th oxidized porcine liver with iron were hexanal, 1-octen-3-one, (Z)-4-heptenal, (E,Z)-2,4-decadienal and (E,E)-2,4-decadienal. These results showed that the fishy and metallic off-flavor in porcine liver were due to the oxidation of unsaturated fatty acids in porcine liver.

Pseudanabaena Species Diversity and Off-flavor Material (2-MIB) Production by Cyanobacteria in Korea (우리나라 Pseudanabaena 속 남조류 종다양성 및 남조류 기원 이취미 물질(2-MIB)의 발생)

  • Kim, Keonhee;Park, Chaehongk;Shim, Yeonbo;Kim, Nan-young;Lee, Soogone;Jang, Jaeyoung;Lee, Karam;Hwang, Soon-Jin
    • Journal of Korean Society on Water Environment
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    • v.37 no.5
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    • pp.381-397
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    • 2021
  • Off-flavor materials (geosmin and 2-methylisoborneol (2-MIB)) produced by microorganisms, such as, cyanobacteria and actinomycetes, cause freshwater use problems worldwide. Due to unpleasant taste and odor, these microorganisms have raised issues especially in drinking water resources. Recently, there has been increasing concern about 2-MIB and causal cyanobacteria, namely, Pseudanabaena, in Korea. However, material production and ecological dynamics remain largely unexplored. This study reviewed the distribution of Pseudanabaena, its species diversity, and the research trend of molecular ecology related to 2-MIB production in Korea. Based on published literature, we found that seven species of Pseudanabaena which include P. mucicola, P. limnetica, P. redekei, P. catenata, P. galeata, P. yagii, and P. cinerea appeared to occur in a variety of Korean water systems. All of these Pseudanabaena species were found in the North-Han River system (Lakes Soyang, Chuncheon, Uiam, and Paldang). Some of these species were also detected in other watersheds, but the precise species diversity was not identified. Species belonging to the Pseudanabaena genus are hard to classify through general microscopic alpha taxonomy, due to their very small cell size and similar morphological characters. Moreover, the potential of 2-MIB production cannot be detected by microscopic observation. Combining molecular ecological techniques, such as, environmental genomic materials (eDNA, eRNA) analyses to conventional methods could be useful to better understand the off-flavor material production and dynamics, thereby providing more efficient management strategies of freshwater systems.

Sensory Characteristics of Cooked Rice Stored in an Electric Rice Cooker (전기보온밥솥으로 보온한 쌀밥의 관능적 특성)

  • Lee, Young-Joo;Min, Bong-Kee;Shin, Myung-Gon;Sung, Nae-Kyung;Kim, Kwang-Ok
    • Korean Journal of Food Science and Technology
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    • v.25 no.5
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    • pp.487-493
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    • 1993
  • The changes of cooked rice stored in an electric rice cooker at different temperature were investigated using sensory and mechanical methodology. The desirability of cooked rice was deteriorated during storage, particulary cooked rice stored at $80^{\circ}C$ had the lowest desirability. As the storage time increased, glossiness, clumpiness, adhesiveness, moistness and sweet flavor of cooked rice decreased but browning and off-flavor increased. The higher storage temperature resulted in the lower in glossiness, firmness, cohesiveness, moistness, sweet flavor and in the more browning, adhesiveness and off-flavor. L and b values measured by Hunter Color Difference Meter were highly correlated with the sensory glossiness and color.

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Analysis of Headspace Volatile Compounds in Cold-stored and Freeze-dried Krill Eupausia superba

  • Park, Jin-Yong;Kim, Ye-Joo;Lee, Yang-Bong
    • Fisheries and Aquatic Sciences
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    • v.17 no.2
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    • pp.189-195
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    • 2014
  • Headspace volatile compounds of cold-stored and freeze-dried Krill Eupausia superba were analyzed to investigate their flavor qualities using a system combining a dynamic headspace isolator, an automatic thermal desorber, and a gas chromatograph-mass-selective detector. Levels of oxidation products of polyunsaturated fatty acids such as aldehydes, alcohols, and ketones, which are known to give seafood a nasty smell because of their low flavor threshold values, increased during cold storage of krill. Notably, levels of 2-methylpropanal, 3-methylbutanal, 2-methylbutanal and 2-butanone increased during its storage. They can be considered index compounds of off-odor according to freshness degradation during storage. By contrast, in freeze-dried krill powder, levels of aldehydes, ketones, and aromatic compounds decreased rapidly. Only alcohols, which did not greatly affect the food flavor, were isolated in large amounts. It was confirmed that levels of oxidized compounds of krill increased during cold storage, but decreased in freeze-dried krill.