• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.1
• /
• pp.106-110
• /
• 2002

The purpose of this study was to examine the effect of different levels of crude pig plasma transglutaminase (TGase) on the quality of milk curd. Different levels (0, 0.1, 0.2, 0.4, 0.8 and 1.0%) of crude pig plasma TGase was added to fresh milk, individually, and then incubated at $35^{\circ}C$. The time of milk curdling was recorded. Simultaneously, rheological properties, L value and microstructure of the samples were measured and observed. The results showed that the time of milk curdling decreased and the curd strength of milk curd increased with increasing of TGase (p<0.05). The softness of milk curd had the highest value when 0.8% TGase was added (p<0.05). However, L value of milk curds was not significantly different among all treatments. The microstructure of milk curd observed by scanning electron microscopy (SEM) became more dense with TGase level increased.

• Journal of the East Asian Society of Dietary Life
• /
• v.14 no.5
• /
• pp.449-456
• /
• 2004

Different types of coagulant and characteristics of its concentration added in the process of making milk curd were compared in this study. The pH of whey decreased when the amount of coagulant increased. The turbidity of whey was decreased when 5% of acetic acid and lemon juice were put into as coagulants. The texture of milk curd made with cow's milk and skim milk was measured the highest when acetic acid and lemon juice were added at 3, 5% of their concentration. The fracturability of milk curd made only with cow's milk decreased as the concentration of each coagulant increased. The cohesiveness was decreased as concentration of coagulant increased. The springiness was slightly changed depending on its coagulant but didn't show much of difference. The gummminess of milk curd made with cow's milk was increased when 3, 5% of coagulant was added. The result of sensory evaluation of milk curd showed that preference of milk curd wasn't depending on types of milk nor its coagulant. Also, flavor preference showed better when lemon juice was added. Preference in texture of milk curd was the highest made with cow's milk and skim milk. Preference in taste was high when 10% of lemon juice was added to skim milk and preference in its appearance showed higher when the alum was added as a coagulant to both cow's milk and skim milk than other coagulants.

• Korean journal of food and cookery science
• /
• v.31 no.4
• /
• pp.485-496
• /
• 2015

This study was carried out to establish the optimal conditions for curd yogurt using saccharified rice solution. A central composite design was applied to investigate the effects of pectin (2.8~8.4 g), skim milk (14~70 g) and oligosaccharide (28~84 g) ratio on the physicochemical and sensory characteristics of curd yogurt using saccharified rice solution. pH, total acidity, and color value, were analyzed and sensory evaluation was performed. The pH of curd yogurt decreased with decreasing pectin and oligosaccharide ratio. The addition of pectin had a significant effect on the viscosity while skim milk had a significant effect on the color value (a and b value). The results of sensory evaluation showed that, oligosaccharide and skim milk had significant effects on sweetness and sour taste. Oligosaccharide and skim milk masked the sour taste of curd yogurt. The optimum range of ingredients for curd yogurt using saccharified rice solution was predicted to be 4.27~4.90 g of pectin, 30.80~41.30 g of skim milk, and 28.00~36.10 g of oligosaccharide. Based on the overlapped results of physicochemical and sensory evaluation, the optimal amounts of pectin, skim milk and oligosaccharide were 4.59 g, 36.50 g and 32.05 g, respectively.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.8
• /
• pp.1212-1217
• /
• 2003

Fifty-two Holstein cows with different phenotypes of $\kappa$-casein ($\kappa$-CN) and $\beta$-lactoglobulin ($\beta$-LG) were selected to provide weekly milk samples for heating at 30, 70, 75 and $80^{\circ}C$ for 2 min. Coagulating properties of heated milk samples measured as rennet clotting time, rate of curd firming and curd firmness at cutting were determined by a Formagraph. Milk samples were analysed for fat and casein. Least squares analyses of data, after adjustments were made for effect of milk casein and fat contents, indicated that although an increase in heating temperatures resulted in less desirable coagulating properties, the effect of milk types was inherent irrespective of heating temperatures. The shortest rennet clotting time (6.06 min), fastest rate of curd firming (5.61 min) and firmest curd (38.05 mm) were obtained from milk with the B variant for $\kappa$-CN and B variant for $\beta$ -LG when preheated at $30^{\circ}C$. It appears that milk bearing $\kappa$-CN B is more resistant to heat perturbation. All milk samples having the $\kappa$-casein AA (milk types AA/AA, AA/AB, AA/BB) did not have a measurable K20 value when preheated at $70^{\circ}C$. This effect was observed for $\kappa$-casein AB (milk types AB/AA, AB/AB, AB/BB) at $75^{\circ}C$ and $\kappa$-casein BB (milk types BB/AA, BB/AB, BB/BB) at $80^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
• /
• v.23 no.10
• /
• pp.1369-1379
• /
• 2010

This study investigated purification and milk-clotting activity of the enzymes produced by Bacillus subtilis var, natto and Rhizopus oligosporus compared with that of commercial rennet. The clotting time, viscosity, tension and microstructure of the curd and electrophoretic patterns of milk proteins were determined. The milk-clotting activity/proteolytic activity ratios (MCA/PA ratio) of B. subtilis, R. oligosporus and commercial rennet were also compared. The results revealed that the curd formed by the commercial rennet had the highest viscosity and curd tension and the shortest clotting time among the three enzymes. However, curd produced by Rhizopus enzymes was ranked as second. From the MCA/PA ratio and electrophoretogram analyses it could be concluded that the enzyme produced by B. subtilis had the highest proteolytic activity, while the commercial rennet had the highest milk-clotting activity. Observations of microstructures of SEM showed that the three-dimensional network for curd formed by commercial rennet was denser, firmer and more smooth. The milk-clotting activity, specific activity, purification ratio and recovery of the purified enzymes produced by both the tested organisms were also determined with ion exchange chromatography and gel filtration.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.14 no.4
• /
• pp.381-386
• /
• 1985

This experiment was conducted to investigate changes of soybean curd yield according to the extension of soaking time during manufacturing of soybean curd. To investigate those changes systematically, transmission electron microscopy and disc-gel electrophoresis were used. The soybean curd yield was increased from 45.0% to 50.5% and 55.4% respectively as soaking time is extended from 5 hours to 10 and 24 hours. The solid extraction and soybean milk coagulation were also increased according to the extension of soaking time. From disc-gel electrophoresis patterns of soybean milk protein and soybean curd protein, numbers of band were increased and major band thickened by expending the soaking time. Most of high molecular bands of soybean milk protein were transfered to soybean curd. Crude 7S proteins of soybean milk and soybean curd in dis-gel electrophoresis were appeared to be 4 and 5 bands respectively, and crude 11S proteins of soybean milk and soybean curd were appeared to be 9 and 8 bands respectively. Of soybean milk bands, most of 11S component transfered to soybean curd. Transmission electron photomicrographs revealed that the dimension of each protein body became larger and the numbers of spherosome around the protein bodies in unit area fewer by extending the soaking time of soybean.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.12 no.3
• /
• pp.137-141
• /
• 1979

A study on the processing of soy curd powder with soybean milk and kril autolasate has been carried out to prolong tile self life and to improve the taste and colour of soy curd. The soy curd was manufactured by coagulation of the soybean milk prepared from soybean through a series of processes of soaking, grinding, heating at $500^{\circ}C$ for 5 minutes and filtration. Ten hours was reasonable as the soaking time of the soybean for the high yield of soybean milk. The use of $3\%$ $glucono-\delta-lactone$ to the weight of the raw soybean showed the best coagulation of the soybean milk at $90^{\circ}C$ in relation to the yield and content of crude protein of the soy curd. The soy curd powder prepared by spray drying of soyben milk could be coagulated at $90^{\circ}C$ by the addition of $glucono-\delta-lactone$ after suspending in water. The powder manufactured by spray drying of the mixture of soybean milk and drill autolasate could also be coagulated under the same conditions to produce the soft soy curd. Another powder prepared by spray drying of the mixture of soybean milk, krill autolysate and $glucono-\delta-lactone$ could be coagulated by standing at room temperature after 2 minutes boiling.

• Korean Journal of Food Science and Technology
• /
• v.23 no.5
• /
• pp.587-592
• /
• 1991

The curd yogurt was prepared from milk or milk added with skim milk powder or four types of rice powder. Acid production by lactic acid bacteria in milk containing additive of 2% (w/v) was investigated and quality of curd yogurt (sensory property and keeping quality) was examined. Some organic acids in curd yogurt were analyzed by HPLC. Four types of rice powder, particularly brown rice, stimulated acid production by lactic acid bacteria more than control (milk yogurt). Among four organisms tested, Leuconostoc mesenteroides and Lactobacillus bulgaricus produced more acid than L. casei and L. delbrueckii. HPLC analysis of organic acids in curd yogurt showed that the amount of lactic acid markedly increased during the fermentation by L. bulgaricus for 24 hours while the amount of citric acid markedly decreased. Addition of rice powders to milk slightly reduced sensory property of curd yogurt. Among four types of rice powder tested, tongil rice added sample showed better sensory acceptability than other samples. When curd yogurt was kept at $5^{\circ}C$ for two weeks, acidity and number of viable cells of curd yogurt were not changed.

• Korean Journal of Food Science and Technology
• /
• v.22 no.6
• /
• pp.700-706
• /
• 1990

The curd yogurt was prepared from milk or milk added with skim milk powder or soy proteins. Acid production by lactic acid bacteria in milk containing additive of 2% was investigated and quality of curd yogurt(sensory property and keeping quality) was examined. Some organic acids in curd yogurt were analyzed by HPLC. The soy proteins, particularly defatted soy flour or soy flour, stimulated acid production by lactic acid bacteria more than skim milk powder. Among the four organisms tested, Leuconostoc mesenteroides and Lactobacillus bulgaricus produced more acid than L. casei and L. delbrueckii. HPLC analysis of organic acids in curd yogurt showed that the amount of lactic acid and acetic acid markedly increased during the fermentation by L. bulgaricus for 24 hours while the amount of citric acid markedly decreased. The major organic acid produced during the fermentation was lactic acid. Addition of soy proteins to milk reduced sensory property of curd yogurt. Among the soy proteins tested, soy protein concentrate or soy protein isolate added sample showed better sensory acceptability than other samples. When curd yogurt was kept at $5^{\circ}C$ for two weeks, titratable acidity, pH and number of viable cells of curd yogurt were not changed.

• Korean Journal of Food Science and Technology
• /
• v.25 no.2
• /
• pp.130-135
• /
• 1993

A curd yogurt was prepared from milk added with skim milk powder of four kinds of cereal. The effect of cereals at 2%(w/v) level on acid production by lactic acid bacteria in milk was investigated. The effect of cereals on quality of curd yogurt (apparent viscosity, sensory property) was also examined. Addition of cereals markedly stimulated acid production by lactic acid bacteria. Among three organisms tested, L. acidophilus produced more acid than others. Apparent viscosity of curd yogurt added with corn was the highest while that with barley was the lowest. Curd yogurt fermented with L. acidophilus showed characteristics of thioxotropic flow. Apparent viscosity of curd yogurt added with cereal markedly increased between 6 and 24 hours of fermentation. Sensory property of curd yogurt added with wheat was judged as better than reference sample, but that with barley was lodged as the worst among all samples.