• Journal of Dairy Science and Biotechnology
• /
• v.35 no.1
• /
• pp.39-45
• /
• 2017

The market for lactose-hydrolyzed milk is growing due to an increased awareness of lactose intolerance, and increased market interest for modified milk with health claims. The aim of this study was to compare the quality characteristics of 2% lactose-hydrolyzed milk with its lactose hydrolysis rate, with the goal of applying the method to dairy product monitoring in the future. We observed that the freezing point of milk significantly decreased with increasing lactose hydrolysis rate. A linear relationship was found between lactose concentration and freezing point, following the equation (y=-50.416x + 767.91). However, no significant changes were observed in other physicochemical properties of the milk (pH, titratable acidity, total solids and color) (p<0.05). In conclusion, we could predict the residual lactose content quickly and easily in 2% low fat milk by measuring its freezing point. This could represent an easy means for assessing the lactose hydrolysis rate of dairy products.

• Korean Journal of Community Nutrition
• /
• v.23 no.6
• /
• pp.488-495
• /
• 2018

Objectives: This study examined the milk intake patterns with lactose and milk fat in Korean male adults using the following variables: milk intake level, awareness of lactose, and milk fat, health problems, and necessity of milk intake. In addition, the factors affecting milk intake were analyzed by multiple regression analysis. Methods: The subjects were 532 males aged 20 years or older among the nationwide milk purchasing group. The subjects were 223 (41.9%) in the 20-29 year age group, 188 (35.3%) in the 30-49 year age group and 121(22.7%) in the over 50 year age group. The survey was conducted using ANOVA and multiple comparative analysis to examine the differences in age and multiple regression analysis was performed to investigate the factors affecting the intake of milk. Results: The intake of milk in the subjects was $538.14{\pm}494.23ml$ per week. There were statistically significant differences in the subjects' age according to processed milk, low fat, nonfat milk, cheese, and ice cream. The perception of milk and lactose and milk fat was recognized as a good food for skeletal health when milk was consumed. Among the milk nutrients, lactose was highly recognized at the age of 20-29, and milk fat was recognized in those over 50 years. In addition to lactose and milk fat, calcium was the most highly recognized among the milk nutrients. Health problems associated with milk were skeletal health, obesity, and lactose intolerance. The perception of lactose intolerance was related to lactose intolerance and fatness, and the dietary behavior was unaffected. Conclusions: This study examined the milk intake patterns of adult Korean males. Many variables were found to be related to the intake of milk. In this study, the milk intake was high when there was no problem with the perception and dietary behaviors of milk nutrition (lactose and milk fat). This study focused on lactose and milk fat, which are major nutrients in milk, and it is a new perspective study among milk-related research.

• Asian-Australasian Journal of Animal Sciences
• /
• v.30 no.12
• /
• pp.1773-1783
• /
• 2017

Objective: This study evaluated the supplementary effect of higher concentrations of various disaccharides on processing yield, major physicochemical properties, and sensory attributes of Chinese-style pork jerky (CSPJ). Methods: CSPJ samples were prepared by marinating sliced ham (4 mm) with three dissaccharides, including sucrose, lactose, and maltose, at 0%, 15%, 18%, 21%, and 24%. Subsequently, the CSPJ samples were dried and roasted. The moisture content, water activity, crude protein, moisture-to-protein ratio, pH, processing yield, shear force, color, and sensory attributes of the CSPJ samples were evaluated. Results: The quality characteristics of CSPJ samples prepared with sucrose were more acceptable. By contrast, CSPJ samples prepared with lactose showed the lowest scores. However, the processing yield and moisture content were the highest for CSPJ samples prepared with lactose, which may be associated with improved benefits for cost reduction. Furthermore, sucrose and lactose supplementation resulted in contrasting quality characteristics; for example, CSPJ samples with sucrose and maltose supplementation had higher sensory scores for color than samples with lactose supplementation. Additionally, most quality characteristics of CSPJ samples with sucrose supplementation contrasted with those of the samples with lactose supplementation; for example, the samples with sucrose supplementation had higher scores for sensory attributes than those with lactose supplementation. Conclusion: Sucrose supplementation up to 21% to 24% was associated with the highest overall acceptability scores (5.19 to 5.80), enhanced quality characteristics, increased processing yield, and reduced production cost.

• Journal of Microbiology and Biotechnology
• /
• v.14 no.2
• /
• pp.225-230
• /
• 2004

A plasminogen kringle domain 1 to 3, rKl-3, was expressed in Escherichia coli under the control of T7 promoter. For the cost-effective production of rKl-3, the induction process was analyzed and optimized. Induction characteristics with lactose were analyzed in terms of induction time and inducer concentration in various culture conditions including batch and high-cell-density fed-batch cultures. In the fed-batch culture, the induction around 6 h after initiation of the DO-stat fed-batch culture resulted in the highest expression level of rKI-3 among the induction points examined. The highest demand of oxygen at this point was crucial for the maximum expression level of rKI-3. As the lactose concentration increased, the expression level also increased, though the expression level showed a plateau above a concentration of 14 mM of lactose. Lactose acted less specifically than IPTG since most of it was hydrolyzed to glucose and galactose. However, using lactose, the cell growth and the maximum expression level of rKl-3 increased by 20% and 24%, respectively, compared with those using IPTG in the fed-batch culture. The lactose seemed to be hydrolyzed by intracellular and extracellular $\beta$-galactosidase liberated by cell lysis at the same time. Residual concentration of glucose was maintained to a a limit of detection by high performance liquid chromatography, and galactose was not consumed by the host strain Escherichia coli BL2l(DE3).

• Korean Journal of Microbiology
• /
• v.23 no.3
• /
• pp.184-189
• /
• 1985

The cured mutant strains (CW, CSM, CEM, CAM) we obtained from Lactobacillus casei YIT 9018 spontaneously and by ethidium bromide treatments. The lactose fermenting ability of those mutants was tested and plasmid was found to have some functions in lactose metabolism. Plasmid (PLC) has been detected in Lactobacillus casei YIT 9018, but has not been detected in mutants CSM, CEM, CAM. These plasmid curred mutants showed a decrease in the ability to produce lactic acid from lactose.

• Journal of Microbiology and Biotechnology
• /
• v.4 no.4
• /
• pp.333-337
• /
• 1994

In order to develop the whey beverage, we examined the optimum conditions for alcohol fermentation by Kluyveromyces tragilis ATCC 46537. The optimum conditions for alcohol production by K. fragilis ATCC 46537 were as follows; pH 4.5, $30^{\cir}C$, with a supplement of 50 g/l of lactose. To develop a continuous production of alcohol from whey, we compared batch fermentation with continuous iermentation in conjunction with UF system. Batch fermentation produced 11.0 g/l of alcohol, whereas pseudocontinuous and continuous fermentation with UF system produced 8.5 g/l of alcohol. To increase the alcohol production, we added 50 g/l of lactose to both fermentations. Batch fermentation with lactose supplement produced 15.7 g/l of alcohol and continuous fermentation with lactose supplement in conjunction with UF system produced 15.0 g/l of alcohol. These results clearly demonstrate that the UF system can be used to increase the alcohol production from whey, supplemented with exogenous lactose.

• Journal of Dairy Science and Biotechnology
• /
• v.33 no.2
• /
• pp.153-157
• /
• 2015

Milk mineral, which is also called milk calcium, was recovered from concentrated skim milk ultrafiltration permeate (CUFP). Lactose, the major constituent of CUFP, was crystallized by the addition of ethanol; lactose precipitation was observed to increase as the ratio of CUFP to ethanol increased. The calcium content of CUFP remained constant at a CUFP to ethanol ratio of 1:2, while it significantly decreased at a CUFP to ethanol ratio of 1:4. When ethanol (95%, v/v) was reused to precipitate lactose out of CUFP, 85% of the initial lactose precipitated out, while 82% of calcium remained soluble in the CUFP after storage for 24 h.

• Microbiology and Biotechnology Letters
• /
• v.17 no.5
• /
• pp.524-528
• /
• 1989

A $\beta$-Galactosidase producing strain, Alkalophilic Bacillus sp, YS-309, has been isolated from soil sample. The strain was capable of producing large amount of intracellular $\beta$-galactosidase in the alkaline media rather than in the neutral media. The preferable medium composition has been determined to be as follows: 0.5% lactose, 0.5% yeast extract, 0.5% soybean meal, 0.1% KH$_2$PO$_4$, 0.02% MgSO$_4$7$H_2O$ 0,0.6% Na$_2$CO$_3$ (pH 9.9). The enzyme was produced by lactose or IPTG as in-ducer. But both Enzyme synthesis and cellular growth were decreased when lactose was added at the higher concentrations than 1.5% (v/v).

• Journal of Microbiology and Biotechnology
• /
• v.1 no.3
• /
• pp.151-156
• /
• 1991

In order to construct a yeast strain having high ethanol tolerance together with good lactose fermentation ability, the protoplast fusion using Saccharomyces cerevisiae STV 89 and Kluyveromyces fragilis CBS 397 was carried out. Auxotrophic mutants of K. fragilis were obtained as a selection marker by treatment of ethylmethane sulfonate. The best mutant for protoplast fusion was selected based on the capabilities of ${\beta}-galactosidase$ production and lactose fermentation. The protoplast fusion using polyethylene glycol and calcium chloride solution led to the fusion frequence of $3{\times}10^{-6}$ and a number of fusants were obtained. Among these fusants, a fusant F-3-19 showed the best results in terms of ethanol tolerance, ${\beta}-galactosidase$ activity and lactose fermentation. The performance of lactose fermentation and ethanol tolerance by this fusant were better than those of K. fragilis. Study on the ethanol tolerance having relation to fatty acid composition and intracellular ethanol concentration revealed that the fusant F-3-19 had a higher unsaturated fatty acids content and accumulated less amount of intracellular ethanol compared with a parent of K. fragilis.

• Journal of the Optical Society of Korea
• /
• v.20 no.1
• /
• pp.199-203
• /
• 2016

An enzyme-free optical method is proposed for estimating high concentrations of glucose in a glucose-lactose mixture, based on a predictive equation that takes advantage of the reflective optical power observed at two discrete wavelengths. Compared to the conventional absorption spectroscopy method based on Beer's Law, which is mainly valid for concentrations below hundreds of mg/dL, the proposed scheme, which relies on reflection signals, can be applied to measure higher glucose concentrations, of even several g/dL in a glucose-lactose mixture. Two probe wavelengths of 1160 and 1300 nm were selected to provide a linear relationship between the reflective power and pure glucose/lactose concentration, where the relevant linear coefficients were derived to complete the predictive equation. Glucose concentrations from 2 to 7 g/dL in a glucose-lactose mixture were efficiently estimated, using the established predictive equation based on monitored reflective powers. The standard error of prediction was 1.17 g/dL.