• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.755-759
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• 1999

To evaluate the effect of sterilizing method on the quality of iron fortified market milk, HTST(high temperature, short time) or LTLT(low temperture, long time) method was adopted after addition of 100ppm ferrous sulfate, ferric citrate, ferric ammonium citrate, or ferrous lactate in market milk. Sterilized iron fortified market milk was stored at 4oC and then pH, lipid oxidation, color change, and sensory quality were observed. The range of pH change in iron fortified market milk sterilized by HTST or LTLT was 6.51~6.74. The order of pH was control>ferric ammonium citrate>ferrous lactate>ferrous sulfate>ferric citrate. Oxygen consumption of ferric ammonium citrate and ferric citrate was lower than ferrous lactate and ferrous sulfate. This trend was same in HTST and LTLT method, but generally oxygen consumption was lower in iron fortified market milk sterilized by LTLT method than by HTST. In total color change, ferrous lactate treatment was closer to control than other treatments. Also sensory characteristics of ferrous lactate treatment was showed better quality than other treatment. From these results, LTLT method was more suitable than HTST method for iron fortified market milk and ferrous lactate was comparably suitable among iron salts used in this study.

• Journal of Dairy Science and Biotechnology
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• v.16 no.2
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• pp.90-97
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• 1998

This study was carried out to investigate changes of microbiological and sensory properties in various heat-treated market milks (LTLT, HTST, and UHT milks) stored at 10$^{\circ}C$ during 15d. Titratable acidity (TA) increased with storage, while pH tended to decrease. During the initial 9d, no difference was found in TA, however, after 9d, it was slightly higher in HTST and UHT milks than that in LTLT milk. In LTLT and HTST milks, total viable cells and psychrotrophs were dramatically increased during storage, In addition coliform and pathogenic bacteria were found at 12 and 15d. In UHT milk, total viable cells were found only at 15d. In sensory evaluation, LTLT and HTST milks developed a negligible off-flavor until 9d. At 12d, it became stronger in HTST milk than that in LTLT milk. In UHT milk, off-flavor was detected at 9d and increased rapidly there-after. The degree of off-flavor was little higher in HTST and UHT milks, compared with that of LTLT milk after 9d storage. These observations indicated that LTLT and HTST milks may not be microbiologically acceptable after 5d, while off-flavor was not detectable until 9d, In comparison, UHT milk keeps a good quality in microorganism until 15d, however, it may not be accepted in sensory aspect after 9d storage.

• Culinary science and hospitality research
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• v.20 no.2
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• pp.54-64
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• 2014

In order to enhance the firmness of retorted onion, long time, low temperature blanching(LTLT) in calcium solution was conducted. Pre-heating onion in calcium solution significantly improved its texture after high temperature sterilization as compared to conventional blanching alone. The improvement of the firmness by the LTLT blanching is related to the formation of strongly cross-linkages between carboxyl groups and divalent cations($Ca^{2+}$) by the action of pectin methy-lesterase(PME) in onion. A maximum firmness of retorted onion was obtained at the condition of pre-heating at $70^{\circ}C$ for 120min in 0.5%calcium solution. This result supports that the activity of PME and the content of bonded calcium in onion were highest at $70^{\circ}C$. Additionally, the reaction of alkali calcium with various divalent cations such as $Mg^{2+}$ provided a function to hydrolyze pectin molecules, resulting in firmer retorted onion in various calcium agents. Further investigation should be carried out to determine the optimal condition for prevention of tissue softening of various retorted vegetables.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.4
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• pp.390-397
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• 1992

This study was carried out to analyze the physicochemical properties of bovine milks, which were heated with LTLT, HTST, UHT pasteurization and UHT sterilization methods and to compare the heat intensity among the heating methods and samples. The mean HMF values per liter milk were measured as 0.66~1.62 $\mu$M (LTLT), 0.9~1.78$\mu$M (HTST), 3.53$\mu$M(UHT pasteurized) and 7.43~8.97$\mu$M (UHT sterilized) in samples, re- sportively. The available Iysine contents per 100ml milk showed 293.2 mg (Raw), 289.2~291.2 mg (LTLT), 298.4~292.4mg (HTST), 272.4~261.6mg (UHT pasteurized) and 279.0mg (UHT sterilized), respectively. The rates of whey protein denaturation were 9.5~11.4% (LTLT), 9.5~17.1% (HTST), 89.3~95% (UHT pas-tsterilized) and 62.7% (UHT sterilized), respectively. The contents of SH groups per g protein were determined as 2.86$\mu$M (Raw) and 2.95~3.15$\mu$M (LTLT), 3.08~3.18$\mu$M (HTST), 3.26~3.42$\mu$M (UHT Pasteurized) and 3. 36$\mu$M (UHT sterilized), respectively, The SS groups Contents per g protein were 28.93$\mu$M (Raw), 25.72~26. 51 $\mu$M (LTLT), 26.93~26.79$\mu$M (HTST), 23.65~23.04 $\mu$M (UHT pasteurized) and 24.69$\mu$M (UHT sterilized), respectively. The ascorbic acid contents per liter milk were measured 6.05mg (Raw), 1.47~1.65mg (LTLT), 2.50~3.85mg (HTST), 2.87~3.69mg (UHT pasteurized) and 4.50mg (UHT sterilized). The changes of some in-dices in milk samples depend on the heating temperature and time ; the HMF values, SH groups, whey protein denaturation rates increased, while the available lysine contents and SS groups decreased in LTLT, HTST, UHT pasteurized and UHT sterilized milks. No remarkable differences were found in heating indicators between LTLT and UHT milks.

• Journal of Food Hygiene and Safety
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• v.10 no.1
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• pp.19-22
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• 1995

Sensory characteristics of various milk samples-low-temperature long-time(LTLT) milk, high-temperature short-time (HTST) milk and ultra-high temperature (UHT) milk-were investigated using chemical analysis and sensory evaluation. The chemical composition was not much different among the milk samples. The results of evaluation of preference for color, flavor, taste and overall desirability of the milk samples by scoring and ranking tests indicated that significant difference on the sensory quality was recognized at 0.01 percent level. UHT milk samples (especially sample F and H) had better sensory acceptability than LTLT milk HTST milk samples.

• Food Science of Animal Resources
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• v.31 no.4
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• pp.596-602
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• 2011

The objective of this study was to analyze the pattern recognition of volatile compounds from different types of milk under LED (Light Emitting Dioxide) irradiation for 6 d. Yellow, red, blue, dark, and fluorescent light were produced using LED equipment. A mass spectrometry-based electronic nose and DFA (discriminant function analysis) were used to determine the change in volatiles from different types of milk under LED irradiation. As the LED exposure time was increased, DF1 of whole milk changed considerably under blue light, while that of skim milk changed significantly under red and yellow light irradiation. Among the types of milk tested, the most light-induced oxidation sample was LTLT milk under blue light. The volatile compounds that were shown to increase due to LED treatment in the electronic nose analysis, which was based on MS, were mainly acetaldehyde, propanal, pentanal, hexanal, heptanal, nonanal, 3-methyl butanal, 2-methyl propanal, 2-butanone, 2-pentanone, 2-hexanone, and 2-heptanaone and 2-nonanone.

• Journal of Dairy Science and Biotechnology
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• v.29 no.2
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• pp.37-42
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• 2011

The changes in pH, titratable acidity, chromaticity, total count, coliform group and organoleptic properties of the whole market milks (UHT, LTLT) that sold currently on the domestic market were stored after their production at 0, 10, 20, 30 and $40^{\circ}C$ to predict their quality during distribution, and examined prior to the analysis on the correlation of their quality properties and organoleptic preference level and discovery of optimal quality indicator. The investigation of correlation between pH, acidity and preference level of milks depending on respective storage temperature showed significant correlation (p<0.01) for the milk stored at 10, 20, 30 and $40^{\circ}C$, and the higher temperature was directly proportional to the higher correlation coefficient. The correlation between total count and preference level for LTLT milk stored at 0, 10, 20, 30 and $40^{\circ}C$ showed high correlation coefficient at every high temperature condition respectively as R=0.81, R=0.91, R=0.96, R=0.90 & R=0.99, and the correlation coefficients were also significant level for the UHT milk irrespective of their storage temperature except $0^{\circ}C$. Accordingly, the changes in total colonies turned out to be suitable to be the quality indicator for the quality prediction of the milk on the distribution.

• Journal of Nutrition and Health
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• v.28 no.2
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• pp.144-151
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• 1995

This study investigates the supplementing effects of milks by various heat treatment on growth performance and protein and calcium metabolism of rats. For 4 weeks, raw, LTLT-HTST-and UHT-processed milks were given to rats which fed on a calcium free, semi-synthetic diet containing 5%casein. There were no significant differences among the experimental groups in weight gain, feed efficiency ratio and the serum level of total protein and calcium. Also, no significant differences were showed in protein efficiency, nitrogen balance, apparent protein digestibiltiy and the contents of weight and calcium of the left femur as well as 2 incisors. However, the biological value of protein in the UHT-milk group was significantly higher than that of the raw-milk group. The apparent calcium digestibility and calcium balance in the UHT-milk group were higher than those in the raw-, LTLT- and HTST-milk groups. The weight of left femur in all the groups supplemented with various heat-treated milks was significantly impair the nutritive value of protein and calcium in milk. Futhermore, UHT-processing may improve the bioavailability of protein and calcium in milk.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.10a
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• pp.302-305
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• 2005

본 연구는 에너지 위기에 따른 고유가 시대에 에너지 소비가 많은 열처리에 의한 시유 생산을 영양적으로나 미생물학적으로 안전하게 대체할 수 있는 방법으로 감마선 조사처리에 대하여 검토하였다. 1, 2, 3, 5, 10 kGy의 감마선 조사시 당일에는 일반세균과 대장균군이 모두 검출되지 않았으나, 냉장상태에서 일주일후에는 1과 2 kGy 조사구에서 일반세균이 검출되었다. 반면 LTLT, HTST, 및 UHT 처리시에도 당일에는 일반세균이 검출되지 않았으나 일주일 후에는 LTLT 처리와 HTST 처리유에서 $10^6$ CFU/mL이상 검출된 반면 UHT 처리유에서는 일반세균이 검출되지 않아, 우유에서 미생물적으로 UHT 처리 정도의 살균효과를 거두기 위해서는 3 kGy 이상의 감마선 조사 처리가 요구되었다.

• Proceedings of the Korean Journal of Food and Nutrition Conference
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• 2000.05a
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• pp.9-11
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• 2000

국민의 영양상태가 크게 향상되어왔고 일부에서는 영양과잉과 운동부족으로 인한 비만에 대한 우려가 고조되고 있지만 최근에도 유아나 성장기 어린이들의 철분부족상태에 대한 문제점이 제기되고 있다. 외국에서는 철분 필요량이 높은 성장기 어린이나 유아들에게 영양학적 품질을 개선한 철분강화제품을 공급하기 위하여 이에 대한 연구가 오래 전부터 진행되어왔으나 여러 실험자에 의하여 행해진 실험조건, 사용된 철분염의 종류가 달라서 정확한 비교평가를 하기에는 미흡하다고 사료된다. 여러 가지 식품에서 특히 우유는 영양학적으로 완전식품이라고 하지만 철분은 거의 함유하고 있지 않아서 효과적으로 철분을 강화할 수 있는 기술은 국민영양개선 효과면에서 매우 유용하다고 사료된다. 본 연구에서는 식품첨가물로서 사용되고 있는 철분염 11종을 우유에 100 ppm수준으로 첨가하고 4$^{\circ}C$에서 저장하면서 pH, 지방산패도, 색도변화를 평가하여 우유에 사용하기 적합한 철분염을 1차적으로 선정하였다. 품질평가 결과를 종합하여 분석할 때 ferric citrate, ferric ammonium citrate, ferrous lactate가 철분강화우유 제조에 적합한 것으로 평가하였다. 또한 지금까지 철분강화식품에 일반적으로 자주 사용하고 있는 ferrous sulfate는 우유에 적합하지 않은 것으로 나타났으나 비교치로 사용하기 위하여 다음 실험에 사용하였다. 이상에서 screening된 철분염을 첨가한 우유를 HTST, LTLT으로 각각 살균하고 저장하면서 품질을 평가한 결과 HTST법이 LTLT법보다 PH, 지방산패도, 색도변화에서 나쁜 것으로 평가되었고, 철분염 종류에 따른 차이는 LTLT, HTST법에서 ferrous lactate가 우수한 것으로 나타났다. 본 연구에서 사용된 철분염 가운데에서는 ferrous lactate, ferric citrate가 유제품에 사용하기에 적합한 것으로 나타났다. 생이용성을 평가하기 위하여 우유에서 low molecular weight components(ILC)를 분리하고 철분과 복합체를 형성시킨 다음, 철분 결핍된 쥐의 소장에서 loop을 형성시켜 ILC-철분 복합체를 injection하여 철분 흡수도를 조사하였다. Ferrous lactate 100ppm에서 약 25.6%흡수되었고 ferric citrate 100ppm은 24.7%, ferrous sulfate는 19.7%흡수되었다. ILC를 첨가하지 않은 100ppm 철분염 용액은 ferrous sulfate를 제외하고는 흡수도가 감소되었다. 철분 결핍된 쥐에게 gavage 방법에 의하여 철분강화우유를 투여하였을 때 철분 25ppm 시료에서는 ferrous sulfate가 12.5%로 가장 높았고 ferrous lactate는 8.1%, ferric citrate는 6.5% 흡수되었다. 철분 100ppm수준에서는 흡수율이 낮아져 ferrous sulfate는 25ppm 시료보다 절반이하 수준이었다. Ferric citrate는 차이가 거의 없었으며 ferrous lactate는 70%수준이었다. 이상의 결과에서 철분강화우유에 사용하기 적합한 철분염은 ferrous lactate, ferric citrate였는데 특히 ferrous lactate는 제품의 이화학적 품질, 생이용성 측면 모두에서 가장 좋은 것으로 나타났다.