식물성 대체식육 제조의 기초단계로 Soy protein isolate (SPI)를 이용한 dough의 물성학적 변화에서 CaCl2과 glucono-delta-lactone (GdL)에 의한 textural properties 영향에 대한 연구를 수행하였다. Soy protein isolate 20% (w/w) dough에 CaCl2 (0~2.0 g/100g) 또는 GdL (0~2.0 g/100g)을 첨가하여 90°C 30 min 열처리 후 textural profile analysis를 평가하였다. CaCl2 농도가 증가함에 따라 SPI dough의 hardness, gumminess, chewiness, cohesiveness, resilience가 점차 감소하였다. 반면 GdL 첨가에 의해서 hardness, gumminess, chewiness의 유의적 증가가 관찰되었고, cohesiveness, resilience가 약간 감소되었다. SPI dough의 springiness 변화에서 CaCl2 또는 GdL 첨가에 의한 영향이 없는 것으로 나타났다. 보수력 변화에서 CaCl2 1.5, 2.0 g/100g 첨가량에서 보수력의 유의적 감소가 관찰되었고, GdL 첨가량 0-2.0 g/100g 범위에서 보수력 변화는 관찰되지 않았다. Ca2+과 GdL은 protein coagulation에 영향을 미쳐서 SPI dough의 물성 변화가 유도된 것으로 사료되었다. 이를 근거로 향후 SPI를 이용한 식물성 대체식육 제조 시 anisotropic texture를 유도할 수 dough제조를 위한 기초 자료로 활용하고자 한다.

The objective of this study was to determine the effect of moisture content(45, 50, 55%), barrel temperature(140, 150°C), screw speed(150, 250 rpm) and two die configurations on the physical properties of extruded soy protein isolate(SPI). Water holding capacity(WHC), texture, integrity index and nitrogen solubility index(NSI) of extruded SPI were analyzed. The texture of extruded SPI was affected by the die configuration. The physical properties of extruded SPI was significantly influenced by barrel temperature, moisture content and die configuration. The increase in water injection rate and barrel temperature led to increase WHC and NSI. The higher water injection rate led to increase integrity index and texture(elasticity, cohesiveness, chewiness, cutting strength). The extruded SPI at 8 cm die configuration had higher integrity index than those of the 5 cm die configuration. Integrity index and NSI were negatively correlated. Thus, the die configuration can be useful to control quality of extruded SPI.

The objective of this study was to determine the effect of moisture contents (40, 50, 60%) and CO2 gas injection (0 and 800 mL/min) on physicochemical properties of extruded soy protein isolate (SPI). The expansion ratio and specific length at 40 and 50% moisture contents with CO2 gas injection increased while piece density decreased. On the contrary, the expansion ratio and specific length of extruded SPI at 60% moisture content with CO₂ gas injection decreased while piece density increased. Extruded SPI with CO2 gas injection had small cell size and higher amount of cell than extruded SPI without CO2 gas injection. The water holding capacity and nitrogen solubility index increased with CO2 gas injection increased while the integrity index and the springiness and cohesiveness decreased. In conclusion, extruded SPI with CO2 gas injection showed better expansion properties and cell formation than extruded SPI without CO2 gas injection.

The objective of this study was to determine the effect of moisture contents (40, 50, 60%) and CO2 gas injection (0 and 800 mL/min) on physicochemical properties of extruded soy protein isolate (SPI). The expansion ratio and the specific length increased, but piece density decreased with the increase in CO2 gas injection from 0 to 800 mL/ min at both 40 and 50% moisture contents. On the contrary, the expansion ratio and the specific length decreased, but piece density increased with the increase in CO2 gas injection from 0 to 800 mL/min at 60% moisture content. Extruded SPI with CO2 gas injection at 800 mL/min had small cell size and higher amount of cell than extruded SPI without CO2 gas injection. The water holding capacity and nitrogen solubility index increased, and the integrity index and the texture decreased with the increase in CO2 gas injection from 0 to 800 mL/min. In conclusion, extruded SPI with the CO2 gas injection at 800 mL/min showed better expansion properties and cell formation than extruded SPI without the CO2 gas injection.

The objective of this study was to determine the effect of moisture contents (40, 50, 60%) and CO2 gas injection (0 and 800 mL/min) on physicochemical properties of extruded soy protein isolate (SPI). The expansion ratio and the specific length increased, but piece density decreased with the increase in CO2 gas injection from 0 to 800 mL/ min at both 40 and 50% moisture contents. On the contrary, the expansion ratio and the specific length decreased, but piece density increased with the increase in CO2 gas injection from 0 to 800 mL/min at 60% moisture content. Extruded SPI with CO2 gas injection at 800 mL/min had small cell size and higher amount of cell than extruded SPI without CO2 gas injection. The water holding capacity and nitrogen solubility index increased, and the integrity index and the texture decreased with the increase in CO2 gas injection from 0 to 800 mL/min. In conclusion, extruded SPI with the CO2 gas injection at 800 mL/min showed better expansion properties and cell formation than extruded SPI without the CO2 gas injection.

The objectives of this investigation were to study the effects of moisture content, screw speed and barrel temperature on physical properties of extruded soy protein isolate (SPI) with L-cysteine and xylose. SPI with L-cysteine and xylose was extruded at 30 and 35% moisture contents, screw speed 150 and 250 rpm and barrel temperatures 140 and 160℃. SPI extruded at 30% moisture content, screw speed 250 rpm and barrel temperature 140℃ was control (100% SPI). Increasing barrel temperature and moisture content decreased expansion ratio of all extrudates but increasing screw speed increased expansion ratio. Moisture content, screw speed and barrel temperature affected the color (L, a, b, ΔE) of extrudates. Water absorption index (WAI) and fat binding capacity (FBC) increased with increasing barrel temperature and screw speed. WAI and FBC were the highest at 30% moisture content. The pore structure of extrudates was a finer at barrel temperature 160℃. The increase in screw speed and moisture content showed more organized fibrous and thicker cell walls. The extrusion condition and the addition of L-cysteine and xylose may improve physical properties such as the structure-forming and textures of extruded SPI products.

The effects of substituting whey protein isolate (WPI) powder for rice flour during the preparation of paeksulgi (Korean rice cake) were evaluated by objective and subjective tests. Milk whey is drained from milk curd as a by-product of the cheese manufacturing process. Whey protein is known as a good nutritional source and a functional material for many processed foods. WPI contains more than 90% whey protein. The moisture content decreased gradually during storage and the decrease was less in control than WPI powder-substituted groups. The color lightness (L) decreased significantly with increasing WPI powder, wherease the redness (a) and yellowness (b) both increased. Texture analyses revealed that the hardness, chewiness, gumminess, adhesiveness and fracturability of paeksulgitended to increase in proportion to the amount of WPI powder added. Evaluation of the gelatinization of paeksulgi by amylographing revealed that the initial pasting temperature, peak viscosity, hot pasting viscosity and breakdown was lower in samples that contained WPI powder. However, the lowest setback value was observed in the control. The results of the sensory evaluation indicated that paeksulgi prepared with 2% WPI powder had the highest overall acceptability. Taken together, these results suggest that WPI paeksulgi containing 2% WPI powder has the best quality.

In this study, physicochemical properties and the antioxidative activity of whey protein isolate(WPI) for com germ oil were measured. The pH of WPI was 6.26, and the titrable acidity was 0.18%. The WPI’s moisture content was 5.2% and each of the other element content such as lactose, crude protein, crude ash and crude fat was found to be 0.8%, 90.7%, 2.7% and 0.6%, respectively. The amounts of active SH group in WPI 9 μ M-g and total colony counts of bacteria was 5.9 × 103 CFU-g. α-Lactalbumin, β-lactoglobulin and bovine serum albumin(BSA) were shown in WPI as major protein by electrophoresis. The antioxidative effect of WPI and other antioxidants on com germ oil used as substrate was determined by peroxide value(POV) and conjuqated dienoic acid value(CDV). By these results, the order of antioxidative effects could be defined as BHT 0.02%〉ascorbic acid 0.1%〉WPI 0.1%〉WPI 0.02%〉ascorbic acid 0.02%〉control〉tocopherol 0.02%〉tocopherol 0.1%, respectively. Also the induction period of com germ oil added with WPI was longer by 1.6 times than that of control(none added any antioxidant). Therefore the fact suggested that WPI could be utilized as a good antioxidative agents.

This study was conducted to improve the functional properties of soybean protein isolate by dimethylglutarylation and acetylation. Amino acid composition and solubility of modified soybean protein by dimethylglutarylation were not changed, but lysine and trypsin inhibitor activity was decreased an isoelectric point was moved from pH5 to pH4 as a result of modification. Emulsification capacity and stability, foaming capacity and thermal stability were increased by the modification. In that 91% dimethylglutarylated protein did not coagulate when heating at 100℃ for 20 min. while its foaming stability was decreased. Whereas specific gravity was decreased by the modification of the soybean protein, relative viscosity and whiteness were improved. Generally, dimethylglutarylation produced more conformational changes in protein system than did in acetylation.

We studied to improve the functional properties of soybean protein isolate by dimethylglutarylation and acetylation. Soybean protein isolate was acylated rapidly up to 80% modification and more of 80% modification was proceed slowly. Electrophoretic analysis showed that more changes in modified protein. Also, modification of soybean protein produced more ionizable tyrosines and exposed more hydrophobic groups, while modified protein exhibited a loss of reactive sulfhydryl groups. Spectrophoretic studies demonstrated that the shift was occurred at the UV 278nm and fluorescence 333nm, respectively, and the intensity decreased as the degree of modification was increased.

Cheese analogs using lipoxygenase-defected soymilk and α -chymotrypsin modified soy protein isolate (SPI) were prepared. Color, textural properties, sensory attributes and melting spreadability of cheese analogs were evaluated and compared with mozzarella cheese, and relationships between textural properties, sensory attributes and melting spreadability of cheese analogs were analyzed. Off-flavors were not mostly discriminated. Cheese analogs containing 10% SPI untreated and containing 6% and 8% SPI treated by α -chymotrypsin in δE value of color were the most similar to mozzarella cheese. Quality characteristics and melting spreadability of cheese analogs were highly affected and improved by α -chymotrypsin modification. Sensory attributes and melting spreadability of cheese analogs containing 6% SPI treated by α -chymotrypsin were the most similar to mozzarella cheese, while in textural properties, cheese analogs containing 10% SPI were the most similar with mozzarella cheese. Hardness in sensory attributes was highly positively correlated with hardness (r>0.65), adhesiveness (r>0.56), chewiness (r>0.77) and gumminess (r>0.76) in textural properties, while it was highly negatively correlated with melting spreadability (r>-0.68).