• Journal of Dairy Science and Biotechnology
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• v.14 no.2
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• pp.185-193
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• 1996

This study was to investigate principle of freeze concentration such as nucleation, crystal growth and procedure of freeze concentration, essential factor and application of freeze concentration. Especially, quality of milk was emphasized. For exemple, in sensory evaluation of freeze concentrated and reconstituted skim milk and whole milk, taste, color, mouth feel and texture were superior to control. Recently developed technique of freeze concentration for quality milk and dairy products may be expected for advanced quality of various milk and dairy products in near future.

• Food Science and Biotechnology
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• v.15 no.5
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• pp.756-762
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• 2006

Freeze concentration of milk was carried out through the controlled recrystallization of ice in a multi-stage freeze concentrator. Rheological characteristics of ice slurries were analyzed to determine efficient concentration levels for the freeze concentration process. It was determined that efficient concentration level was 17% of total solids in the first and 27% in the second stage. Physicochemical properties were compared between freeze concentrated and evaporated milk. Freeze concentrated milk was more similar in color appearance to control milk than was evaporated milk. pH significantly decreased in evaporated milk than in freeze concentrated milk. pH of freeze concentrated milk resulted in similar value to control. These results indicated the advantages of freeze concentration as a non-thermal milk processing technology in terms of physicochemical properties. Consequently, we investigated the influence of ice recrystallization on the rheological characteristics of ice slurries and physicochemical properties of freeze concentrated milk.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.05a
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• pp.297-302
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• 2005

Physicochemical properties were compared between freeze concentrated and vacuum evaporated milk through colour, brix, viscosity, freezing point and pH measurement. Brix and viscosity in each concentrated milk significantly increased due to solute concentration(p<0.05), and there was not much difference between freeze concentrated and evaporative one. Brix results were numerically modeled with the logarithmic regression: Y=-33.460+18.4513 ${\cdot}$ ln(X), $R^2=0.9798$ and this model was fairly fit to predict the solute concentration in the middle of freeze concentration process. Freezing point significantly decreased according to concentration increment(p<0.05) and there was not the significant difference between freeze concentrated and evaporated one. Whereas, in colour and pH value, there were some differences between freeze concentrated and evaporative milk. Vacuum evaporated milk expressed higher discoloration comparing to freeze concentrated one. In pH values, evaporated milk showed the significantly decreased results comparing to freeze concentrated sample, whereas the pH value of freeze concentrated sample expressed the similar value to the reference milk.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.196-201
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• 2006

Freeze concentration of milk was carried out thorough the controlled recrystallization of ice in a multi-stage freeze concentrator. Artificial temperature control was used to induce ice recrystallization via a heat and cold shock process. In each stage of freeze concentration, the recrystallization time was fixed at 1, 2, 4, and 8 hr to compare the solute concentrate, yield, Brix, ice crystal size, and freezing point at each experimental condition. Higher concentrations of milk solids were seen with increased durations of recrystallization time, and a maximum total solids in the final product of 32.7% was obtained with a ripening time of 8 hr in a second stage process. Milk solid yield decreased according to the solute concentration and recrystallization time. The results of Brix and ice crystal size showed a positive correlation with recrystallizaiton time. These results suggest the possibility of freeze concentration being of practical use in the dairy industry.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.6
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• pp.984-989
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• 1995

The concentration-efficiencyh of blue dextran solution in the progressive freeze-concentration was related to the freezing conditions such as the freezing speed and the stirring speed in the solution phase. From the theoreticla balance equation of heat and mass transfer at freezing front, the relationship between the freezing conditions and the ice structure at freezing front was drived. A high freeze-concentration efficiency was obtained under the operating conditions represented by a low speed of freezing and a high speed of stirring. The operating conditions were related to a smooth solid-liquid interface and these results were well explained by the theoretical equation. Effect of the solute component size on the concentration efficiency in the progressive freezeconcentration was also tested. The concentration efficiency of latex particles showed a lower value than that of blue dextran, however, its difference was insignificant.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.05a
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• pp.290-296
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• 2005

This study was carried out to develop the efficient freeze concentration process of milk through controlling the recrystallisation phenomena of ice. Freeze-concentration was progressed with multi-stage freeze concentrator and there was artificial temperature control to induce recrystallisation phenomena. In each stage of freeze concentration process, the regular recrystallisation time was fixed as 1, 2, 4 and 8 hr to compare the solute increment, yield, brix and ice-crystal size among experimental conditions. Higher concentration as total solids was observed due to the elapse of recrystallisation time, and the maximum total solids in final products: 32.67% was obtained at the ripening time of 8 hr in two-stage process. This result was excessively high concentration comparing to the existing researches and presented the possibilities of milk freeze concentration in the dairy industry, The results of brix and ice-crystal size showed the direct correlation with the recrystallisation time that meant the increased processing time showed the increment of brix and ice-crystal size. Obtained results were numerically modelled to predict the progress of concentration in the industrial process and all of them had fairly high R2 of determination. Therefore, we regarded that these numerical models could be utilized for the development of efficient technology in industrial freeze concentration process.

• The Korean Journal of Food And Nutrition
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• v.33 no.5
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• pp.512-523
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• 2020

The objective of this study was to investigate the quality characteristics of Cheongsoo wine using freeze concentration fermented with 5 kinds of yeast strains (Saccharomyces cerevisiae EJ18, EJ30, HK22, HK32 and Fermivin). We compared the characteristics, volatile flavor component and physiological activity of 5 wines. The freeze concentration can increase the sugar concentration in grape juice by reducing its water content and the alcohol content of freeze-cententrated Cheongsoo wines ranged between 15.0~15.8%. The pH of wines ranged from 2.92 to 2.94 and the total acidity and soluble solid of wines ranged from 12.40~13.27. °Brix. The major organic acid in the wines was tartaric acid (4.49~5.11 mg/mL) and malic acid (7.00~7.97 mg/mL). It contains higher functional compounds in wine fermented with yeast (EJ18, EJ30, HK22, HK32) than wine fermented with fermivin. α-glucosidase and tyrosinase inhibitory activity had the highest values (78.87% and 62.25%) in wine fermented with HK22 and EJ18 yeast, respectively. 16 volatile flavor compounds (alcohols, esters, ketones, acids, and others) were detected in the Cheongsoo wines by freeze concentration. These results provide useful information that the quality characteristics of wine developed by the freeze-concentration method using grapes cultivated in Korea.

• The Korean Journal of Food And Nutrition
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• v.32 no.5
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• pp.485-493
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• 2019

The purpose of this study was to investigate the quality characteristics and volatile flavor components of Doonuri wine, using freeze concentration. The freeze concentration can increase the sugar concentration in grape juice by reducing its water content. In this study, after eight days od fermentation, the alcohol content of freeze-concentrated Doonuri wines was 12.5~14.1%. The pH of the wine was 3.42~3.50 and the total acid content was 0.68~0.94 g/100 mL, respectively. The brghtness of freeze-concentrated Doonuri wines was 19.28~54.42, the redness was 41.98~49.58, and the yellowness was 36.16~42.36. The organic acid analysis of Doonuri wines was that most of the organic acids contain tartaric and malic acid. By using freeze concentration with grape juice, significant increase in the total polyphenol content of Doonuri wines was 122.40~137.26 mg/mL, the total anthocyanin content was 117.06~118.40 mg/L and the tannic acid content was 66.23~83.70 mg%. In GC/MS analysis, the volatile flavor component analysis of Doonuri wines identified six alcohols, five esters, two ketones, on acid, two alkanes, and four other compounds.

• Food Science and Biotechnology
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• v.15 no.6
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• pp.844-850
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• 2006

This study was designed to compare various quality characteristics, such as nutrient composition and physicochemical and sensory properties of freeze-concentrated milk made by a newly developed continuous multi-stage process with those of evaporated milk. The freeze concentration process reduced the water content up to 73%. Most of the physicochemical properties of evaporated milk were different from raw milk; however the freeze-concentrated milk showed little difference from the raw milk. The thiobarbituric acid value and free fatty acid concentrations were significantly greater in the evaporated milk than in the freeze-concentrated milk. Several effects on sensory characteristics, such as off-taste, were significantly stronger in the evaporated milk. Overall, this study indicates that the newly developed freeze concentration technique results in improved physicochemical and sensory properties, and has little effect on most nutrient levels when compared with the evaporation process. Further research is necessary to further elucidate the chemical and sensory properties of freeze-concentrated milk.

• Korean Journal of Food Science and Technology
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• v.41 no.1
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• pp.32-36
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• 2009

The physical properties of freeze-dried Aloe vera gel powders were examined according to the influence of the concentration degrees of the gel solutions as raw materials during freeze-drying. As a pre-treatment prior to freeze-drying, the gel solutions were vacuum-concentrated at three concentration levels (g water/g solids): high (H), 76; medium (M), 119; and low (L), 159. The water contents of the three powder samples were almost the same. For their viscosity measurements, non-Newtonian fluid behavior with shear thinning was observed in samples H and M, whereas Newtonian liquid behavior was found in sample L. In electrical conductivity measurements, sample H showed the highest conductivity upon dissolving the powder in water. For their water sorption isotherms, sample H was analyzed to have the least amount of bound water. Finally, it was determined that the degree of concentration caused only slight differences in the physical properties of freeze-dried Aloe gel powders.