• Title/Summary/Keyword: Temperature

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Measurement of Biogenic Amines with a Chitopearl Enzyme Reactor (Chitopearl 효소 Reactor를 이용한 Biogenic Amines 측정)

  • Park, In-Seon;Kim, Dong-Kyung;Shon, Dong-Hwa;Cho, Yong-Jin;Kim, Nam-Soo
    • Korean Journal of Food Science and Technology
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    • v.31 no.3
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    • pp.593-599
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    • 1999
  • Substrate specificity of a flow-injection-analysis (FIA)-type biogenic amine sensor with enzyme reactor was determined. The enzyme reactor was prepared with a diamine oxidase immobilized on preactivated chitosan porous beads (Chitopearl) by intramolecular cross-linking via glutaraldehyde. The sensor showed a rapid response to putrescine and a quasi-linear calibration curve was obtained up to 15.0 mM. The optimal pH and temperature of the enzyme reactor system were 7.5 and $35^{\circ}C$. Interferences due to ATP-related compounds and trimethylamine, and the effects of NaCl and amino acids were measured. Inhibitory effects owing to these components could be mitigated by sample extraction with perchloric acid. Polyamines except putrescine were determined by a putrescine calibration range within 26.7%. This system was confirmed as rapid and convenient for biogenic amine determination.

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Comparison on Physicochemical Properties of Amaranth Starch with Other Waxy Cereal Starches (아마란스 전분과 곡류 찰전분의 특성 비교)

  • Lee, Jae-Hak;Kim, Sung-Ran;Song, Ji-Young;Shin, Mal-Shick
    • Korean Journal of Food Science and Technology
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    • v.31 no.3
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    • pp.612-618
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    • 1999
  • Physicochemical properties of amaranth starch were compared with those of waxy rice and waxy corn starches. Amaranth starch granules vary from $1.1{\sim}1.9\;{\mu}m$ in diameter and are polygonal in shape. Total amylose contents from waxy rice, waxy corn and amaranth starches were 0.01, 0.03 and 0.07%, respectively. Swelling power of amaranth starch granule was slightly different from waxy rice. The swelling power of amaranth increased at $70^{\circ}C$. X-ray diffraction patterns of amaranth and other waxy cereal starches showed an A-type crystalline structure. Relative crystallinities of their starches were similar. According to pasting properties by Rapid Visco-Analyzer, amaranth starch showed a very high gelatinization temperature $(75.1^{\circ}C)$ and lower viscosity and higher stability than other waxy cereal starches during heating and cooling cycle. Peak onset temperatures (To) of starches from waxy rice, waxy corn and amaranth in DSC thermograms were $58.7{\sim}64.0$, 67.2 and $71.5^{\circ}C$, respectively, and their peak enthalpies were similar. Enthalpy of reheated amaranth starch after 3 day storage at $4^{\circ}C$ was higher than those of waxy corn and rices starchs.

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Changes of Internal Pressure during Freezing, Frozen Storage and Thawing of Meats (식육의 동결, 냉동냉장 및 해동시 내부압력 변화)

  • Jeong, Jin-Woong;Kim, Jong-Hoon
    • Korean Journal of Food Science and Technology
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    • v.31 no.3
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    • pp.682-687
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    • 1999
  • The destruction of tissues by volume increase at food freezing is accepted as one of the factor responsible for quality damage. For this reason, the internal pressure developed in meats were investigated with a pressure transducer during freezing, frozen storage and thawing. Increasement of 6.33% for volume and $942.17\;kg/cm^2$ for density at $-20^{\circ}C$ for beef were shown. In quick and slow freezing of beef, internal pressure reached to highest point after reached to the lowest point at initial of the zone of ice crystal formation. The internal pressure was approximately $8{\sim}10\;psig$ and pressure difference was about 1 psig, which was bigger in immersion freezing than that of still-air freezing. During frozen storage of pork, internal pressure of $1.84{\sim}2.32\;psig$ occurred repeatedly as a function of sample weight at material temperature difference of ${\pm}1^{\circ}C$. The internal pressure during thawing of pork was decreased slowly after rapid increase to the maximum for less than 5min at the beginning of thawing. Internal pressure value at thawing was higher than that at freezing in most cases. Internal pressure of beef with thermal equalized freezing was about $1{\sim}4\;psig$, which was lower than that of non-thermal equalized freezing. Also, freezing time was shortened to $10{\sim}20%$.

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Microwave Vacuum Drying of Brown Rice Koji as an Enzymic Health Food (효소식품으로서 현미코오지의 마이크로파 진공건조)

  • Kim, Suk-Shin;Roh, Hoe-Jin;Kim, Sang-Yong
    • Korean Journal of Food Science and Technology
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    • v.31 no.3
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    • pp.625-630
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    • 1999
  • This work was to study drying characteristics of the brown rice koji, an enzymic health food, using microwave under vacuum. Cooked brown rice was inoculated with Aspergillus oryzae and incubated at $32^{\circ}C$ for 6 days. The brown rice koji was dried by different drying methods: microwave vacuum drying, hot air drying, vacuum drying and freeze drying. Each drier except freeze drier was set to maintain the sample temperature at $40^{\circ}C$. During microwave vacuum drying, the sample reached $40^{\circ}C$ much faster (within $5{\sim}10\;min$) and was dried much faster (2 hrs) than the other drying methods. The initial drying rate of microwave vacuum drying was ten times faster than that of hot air drying. The microwave vacuum drying produced a dry sample of the highly retained enzymic activity, followed by freeze drying, vacuum drying, and hot air drying.

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Various Properties and Phenolic Acid Contents of Rices and Rice Brans with Different Milling Fractions (품종 및 도정도별 백미와 미강의 특성 및 페놀산 함량)

  • Kim, Sung-Ran;Ahn, Ji-Yun;Lee, Hyun-Yu;Ha, Tae-Youl
    • Korean Journal of Food Science and Technology
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    • v.36 no.6
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    • pp.930-936
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    • 2004
  • Effects of rice cultivars and degree of milling (DM) on composition, pasting properties, total phenolic contents, and distribution of phenolic acids were investigated. Rice and bran fractions with 94.4, 92.0, and 90.4% milling yields from brown rice of four cultivars (Odae, Nampyung, Chucheong, and Ilmi) were used. Fat and ash contents of milled rices decreased with increasing DM, whereas protein contents were not affected. In rice bran, differences in fat and ash contents by cultivars were higher than those caused by DM. With increasing DM, gelatinization temperature of rice flour decreased, whereas peak viscosity and hold viscosity at $95^{\circ}C$ increased. While cold viscosity, final viscosity, and setback varied among cultivars, DM had little effect. Total polyphenolic contents in brown rice, milled rice, and rice bran were 93.9-88.8, 30.3-71.9, and 310.0-541.6 mg catechin eq/100g, respectively. Major phenolic compounds were identified as ferulic and p-coumaric acids. Total phenolic content of brown rice (65.9-27.9 mg%) decreased with increasing DM, whereas ratio of ferulic acid composition increased. Chucheong and Ilmi varieties showed biggest reduction of phenolic acid contents by milling. In rice bran, ferulic and p-coumaric acids were 157.8-240.2 and 31.8-90.4 mg%, respectively. Contents of sinapinic, benzoic, and m-hydroxybenzoic acids in rice bran were higher than those of brown and milled rices.

Quality Characteristics of Chocolate Blended with Bifidobacterium-fermented Isoflavone Powder (Bifidobacterium으로 발효한 이소플라본 함유물 첨가 쵸코렛의 품질 특성)

  • Moon, Sung-Won;Park, Myung-Soo;Ahn, Jun-Bae;Ji, Geun-Eog
    • Korean Journal of Food Science and Technology
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    • v.35 no.6
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    • pp.1162-1168
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    • 2003
  • Development of chocolate products to improve the quality and functional properties with Bifidobacterium-fermented isoflavone powder (BFIP) was attempted. Effects of BFIP on sensory value, isoflavone contents, and microbiological characteristics of chocolate products during storage at room temperature $(24{\pm}0.5^{\circ})$ for 90 day were studied. Five different BFIP concentrations of 0, 1, 2, 3, and 4% (w/w) were added and blended into the chocolate products. Results of sensory evaluation showed that the scores for softness and bitter taste decreased as the BFIP contents increased. In sweet and sour taste, the highest score was shown at 1% BFIP treatment. In overall acceptability, 1% treatment was the most favored, followed by 2% treatment. Contents of isoflavone in chocolate products were stably maintained during 90 storage days. The viable cell numbers of Bifidobacterium remained relatively stable until 70 day, followed by a slow decrease thereafter in all treatments.

Production and Characteristics of Lytic Enzyme against Streptococcus mutans Cell Wall from Alkalophilic Bacillus sp. 4830 (호알카리성 Bacillus sp. 4830이 생산하는 Streptococcus mutans 세포벽 분해효소의 분리와 특성)

  • Kim, Yun-Keun;Bai, Dong-Hoon
    • Korean Journal of Food Science and Technology
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    • v.35 no.6
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    • pp.1143-1149
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    • 2003
  • To elucidate a method of preventing dental caries, strains producing lytic enzymes were isolated and their characteristics were investigated. Among 5,00 alkalophilic strains isolated from soil, 22 strains showed lytic activity against Streptococcus mutans. Strain No. 4830, with the highest lytic activity, was selected for further study. Strain 4830 showed 94% sequence homology with the 16S rDNA sequence of Bacillus alcalophilus, but it was concluded to be different from Bacillus alcalophilus because of its biochemical characteristics. The strain was named Bacillus sp. 4830. The lytic enzyme from Bacillus sp. 4830 was purified by ethanol precipitation and CM-agarose column chromatography. The molecular weight of the lytic enzyme was determined to be 28 kDa by SDS-PAGE. The lytic enzyme was stable between pH 5.0 and pH 11 and up to $40^{\circ}C$. The optimal pH and temperature for the lytic activity was 9.0 and $50^{\circ}C$, respectively.

Comparison of Gelatinization and Retrogradation Characteristics among Endosperm Mutant Rices Derived from Ilpumbyeo (일품벼 유래 배유 돌연변이품종 쌀의 호화 및 노화 특성 비교)

  • Kang, Hee-Jin;Seo, Han-Seok;Hwang, In-Kyeong
    • Korean Journal of Food Science and Technology
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    • v.36 no.6
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    • pp.879-884
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    • 2004
  • Effects of soaking time and particle size on physicochemical properties of nonwaxy rice flour were investigated. Nonwaxy rice grains were soaked at $4^{\circ}C$ for 0, 1, 12, and 24 hr, dried at room temperature, and milled. Resulting flours were passed through 45-mesh ($<355\;{\mu}m$, IL45) and 100-mesh ($<150\;{\mu}m$, IL100) sieves and separated into $<40\;{\mu}m\;and\;40-100\;{\mu}m$ series. IL45 series showed higher amount of large particles ($40-100\;{\mu}m$) than IL100 series. As the soaking time increased, protein and ash contents decreased, and amylose content, water-binding capacity, swelling power, and solubity of nonwaxy rice flours increased. Swelling power and solubility of nonwaxy rice flours also increased between $65-85^{\circ}C$. Water-binding capacity, swelling power, and solubility of IL100 series were higher than those of IL45 series. 12 hr-soaked nonwaxy rice flour pastes showed higher peak viscosity and breakdown but lower setback and viscosity at 95 and $50^{\circ}C$ than 1 hr-soaked ones. X-Ray diffractograms of nonwaxy rice flours were not affected, whereas surface appearance was affected, by soaking time and particle size.

The Inhibition of Green Discoloration in Garlic by Conditioning (Conditioning에 의한 마늘의 녹변억제)

  • Hwang, Jin-Bong;Shin, Dong-Bin;Park, Wan-Su;Lee, Young-Chun
    • Korean Journal of Food Science and Technology
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    • v.35 no.6
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    • pp.1007-1016
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    • 2003
  • Garlic was stored at 4, 8, and $12^{\circ}C$ to investigate the development of green discoloration. Green discoloration developed after 7 day of storage ar $4^{\circ}C$, while it developed after 15 day of storage at 8 and $12^{\circ}C$. The effect of maleic hydrazide fertilization on green discoloration of garlic was not observed. Green discoloration of garlic was accelerated by gamma-radiation treatment. The addition of cysteine did not prevent green discoloration, which decreased the commercial value of the garlic due to the presence of white specks on the surface. When 3% ascorbic acid was added to the garlic, green discoloration developed in 6 and 24 hr at room temperature and $4^{\circ}C$, respectively. The tendency of garlic to discolor was also investigated at various storage temperatures. Discolored garlic stored for 30 day at low temperatures was conditioned at $20{\sim}45^{\circ}C$ for 20 day. The green discoloration of garlic conditioned at 20 and $25^{\circ}C$ did not disappear in 20 day, but disappeared in 20 day when conditioned at $30^{\circ}C$. The L, a, and b values of garlic conditioned at 35, 40, and $45^{\circ}C$ for 4 day were similar to those of normal garlic. Conclusively, our results indicated that the best method for suppressing green discoloration was conditioning discolored garlic at $35^{\circ}C$ for 4 day.

Effects of Frying Oils and Storage Conditions on the Rancidity of Yackwa (약과(藥菓)의 산패(酸敗)에 미치는 튀김기름 및 저장조건의 영향)

  • Min, Byung-Aye;Lee, Jin-Hwa;Lee, Su-Rae
    • Korean Journal of Food Science and Technology
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    • v.17 no.2
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    • pp.114-120
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    • 1985
  • This study was carried out to investigate the storage stability of Yackwa (a Korean fried cake made from wheat flour, honey and 20% oil), with the variation in frying oils (soybean oil of fresh or heat-treated corn oil and rapeseed oil) and storage conditions (temperature, humidity and in dark or under fluorescent light) for 20 weeks period. In $5^{\circ}C$ storage, acid and peroxide values increased slowly, showing the peroxide value of 20 meq/kg after 13 weeks. In $40^{\circ}C$ storage, acid and peroxide values increased remarkably. The product became harder at storage humidity of 25% and softer by moistening at storage humidity of 80%. Acid and peroxide values of Yackwa from corn, rapeseed and soybean oils increased with storage period, to a different extent. The values of fluorescent groups, especially rapeseed oil group, were higher than those of control groups and the heat-treated oil groups were higher than those of fresh oil groups. Sensory scores for rancid flavor were gradually increased with the storage period in all groups. There was no significant difference with the kinds of frying oils, storage conditions and heat treatment. Correlation of sensory scores with acid values was positive throughout whole storage period, with low ${\gamma}-values$. Its correlation with peroxide values was positive up to 6th week but negative at 9th week of storage.

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