Changes of tofu structure and physical properties in coagulant concentration

Transcription

1 Changes of tofu structure and physical properties in coagulant concentration Tofu curd formation from soymilk (by T.Ono) Soluble proteins Particle protein Oil body Phytin Tomotada Ono, Yuzuru Onodera, Chen Yeming, and Katuhiko Nakasato Soymilk Coagulant Coagulate Tofu curd Iwate University, Biochemical & Food science The new idea of tofu curd formation has been introduced by us, years ago. Soymilk looks like bovine milk containing micellar protein particles and fat globules. Soymilk also contains particle proteins and oil body. Tofu curd formation from soymilk (by T.Ono) By the increase of / protein ratio, particulate protein was increased. Braking stress of tofu curd with and GDL were increased, too. Soluble proteins Particle protein Oil body Soymilk Phytin Coagulant Coagulate Tofu curd When coagulant is added, Particle proteins adhere to oil body surface. These oil bodies are able to combine each others. Then, the protein-packed oil bodies form tofu curd containing water. Particulate protein (%) Particle% GDL : 1:3 : 3:1 : / ratio 1 ( 3 xn/cm ) Braking stress ( (Guo & Ono, JFS 5) By the increase of content, the more coagulant was needed for the aggregation of soy proteins in soy milk. When Tosan5 ( rich) in soymilk of mixed soybeans increased, the coagulant concentration for protein aggregation increased. olubility (%) Protein so Y/T= / Y/T=7 / 3 Y/T=5 / 5 Y/T=3 / 7 Y/T= / 1 1 CaCl CaCl (mm) (Guo,,, & Ono, JFS ) G: Yumeminori,C: Tosan5 ( rich) ( rich) The soy milk containing the more protein has the more particulate proteins, and makes the more hard tofu texture. On the other hand, the soy milk containing the more protein needs the more coagulant for the protein aggregation. In this experiment, the change of the tofu texture by the variation of / ratio and coagulant concentration was studied. The optimal coagulant concentration was estimated for soymilk from the soybeans having different / ratio Tofu were made from the soybeans having different / ratio by adding coagulants of various concentrations. The physical and the electron microscope of the tofu were measured. 1

2 Materials & Methods Soybeans: Tosan5 (T, rich), Yumeminori (Y, rich),, Tamahomare, Enrei, Nakasennari Mixed soybeans; T:Y = :, 1:3, :, 3:1, : Commercial soybeans; Soymilk added 7 times water of soybean, Preparation: grinding for min, heating for 5min at more 95ºC filtered with defatted cotton sheet soymilk TY-soymilk from mixed soybeans of Tosan & suzukari CM-soymilk from commercial soybeans Tofu preparation Soymilk (TY-soymilk or CM-soymilk) added coagulant (CaSO H O;.15,.,.35,.5%) standing for min at ºC cooled to room temp. Tofu (filled type) TY-tofu form TY-soymilk CM-tofu from CM-soymilk Measurement of physical properties of tofu (5x13mm) penetration test ( mm plunger) with Rheometer Scanning electron microscopy of tofu fixed with glutaraldehyde freeze drying post-fixed with osmium tetraoxide tofu sample scanning electron microscope (JSM-5LV ) Protein patterns of Mixed soybeans by SDS-PGE cidic Basic ST : 3:1 : 1:3 : (T:Y) (T, Tosan5) (Y, Yumeminori) Tosan5 : Yumeminor Protein composition of mixed soybean soymilk from T:Y=: to : were calculated and are shown below. T:Y = : is about : = :, and T:Y = : is about : = 7 : 3. : 1:3 : 3:1 : % % % % % % Protein composition TY-tofu in this experiment were made from these mixed soybean soymilk. This Figure shows the relationship between braking stress of TY-tofu and coagulant concentration. The increase in the content (T/Y from : to :) induced in quick attainment of the maximum braking stress at low coagulant concentration. The values in (Tosan5) rich is like this, and The values in (Yumeminori) rich is like this. ss (kpa) Braking stres.15%.%.3%.5% : 3:1 : 1:3 : (T:Y) : This Figure shows the relationship between strain rate of TY-tofu and coagulant concentration. The increase in the content (T/Y from : to :) induced in quick attainment of the maximum strain rate value at low coagulant concentration. The values in (T) rich is like this, and The values in (Y) rich is like this. -) Strain rate ( %.%.3%.5% : 3:1 : 1:3 : (T:Y) :

3 The relationship between Yang s modulus of TY-tofu and coagulant concentration are shown in Figure. The tendency of value variation against coagulant concentration is almost the same as the values of braking stress and strain rate as shown before. s (kpa) Yang's modulu 15 5 (T:Y).15%.%.3%.5% : 3:1 : 1:3 : (T:Y) : This Figure shows the relationship between water holding capacity of TY-tofu and coagulant concentration. Water holding capacity of TY-tofu was decreased with increasing coagulant concentration in spite of T()/Y() ratio. ng capacity Water holdin % 7% % 5% %.15%.%.3%.5% CaSO : 3:1 : 1:3 : (T:Y) : Scanning electric microscopes of TY-tofu against coagulant concentration are shown in figure. Magnification is TY-tofu from upper to bottom line are T:Y= :, :, and :. Coagulant concentration from left to right are.15,.3, and.5% CaSO.15% 3%.3%.5% T : Y : CaSO T : Y : :.15%.3%.5% T:Y(:) tofu shows a thin wall & large cell-like network at.15% coagulant, a uniform fine network at.3%, and the non-uniform network at.5%. T:Y(:) tofu shows a thin wall & large cell-like network at.15% coagulant, a uniform network at.3%, and the rough & non-uniform network at.5%. : : : m T:Y(:) tofu shows a fine network at.15% coagulant, a rough & non-uniform network at.3%, and the big holes & thin wall network at.5%. m Mag: X5 m The just coagulant concentration is low in rich tofu, & high in rich tofu. Coagulant () Tofu shows thin flat wall & big cell-like network at low coagulant. m t too much coagulant, tofu shows large non-uniform cell-like network & non-flat wall t just coagulant concentration, tofu shows a fine uniform network. m.15%.5% t the changing point of texture, the tofu shows a fine network. The point of -rich tofu is in high coagulant concentration, The point of -rich tofu is in low coagulant concentration. was decreased with increasing coagulant in spite of / ratio. Breaking stress, Y s Ma Strain rate.15%.5% 3

4 Is this theory adapted to commercial soybeans? Protein composition of commercial soybeans are shown in figure as a SDS-PGE pattern Enrei 3.. Miyagishirome 5. Tamahomare. Nakasennari These are major soybeans for tofu proceeding in Japan. The ratio of / was analyzed by an image analyzer. is rich in protein, and Fukuyuta is rich in protein. These soybeans were used for the next experiment. Tamahomare Enrei Nakasennari Ryuho Miyagishirome % % % % % % Protein composition β cidic Basic The braking stress of tofu from commercial soybeans against coagulant concn., rich, is the blue line, and changing point of values is about.%., rich, is the red line, and changing point of values is about.%. The strain rate of tofu from commercial soybeans against coagulant concns., rich, is the blue line, and changing point of values is about.%., rich, is the red line, and Changing point of values is about.%. Breaking st tress kpa %.%.3%.%.5% CaSO Tamahomare Nakasennari Enrei n rate Strain 7% % 5% % 3% %.%.%.3%.%.5% CaSO Tamahomare Nakasennari Enrei This Figure shows the relationship between water holding capacity of CM-tofu and coagulant concentration. Water holding capacity of CM-tofu was decreased with increasing coagulant concentration in spite of T()/Y() ratio rich Scanning electric microscopes of & tofu at Magnification X. 9% capacity Water holding % 7% % 5%.%.%.3%.%.5% rich.15%.3%.5% CaSO Tamahomare Nakasennari Enrei

5 (Mag; X) rich.15%.3%.5% ( rich) tofu at.5% coag. Is in changing point of texture..15%.5% rich tofu shows a thin wall & large cell-like network at.15% coagulant, the similar network at.3%, and a uniform fine network at.5%. Thin & large Flat & uniform Flat & fine tofu shows a uniform fine cell-like network at.15% coagulant, a large cell-like network at.3%, and not-flat big cell network at.5%. Non-flat m Fukuyu ( rich) tofu at.% is in changing point of texture. S rate Fuku B stress B stress S rate.15%.5% Summary.15%.5% t the changing point of texture, the tofu shows a fine network. -rich tofu is in high coagulant concentration, -rich tofu is in low coagulant concentration. was decreased with increasing coagulant in spite of / ratio. Breaking stress, Y s Ma Strain rate.15%.5% 5