Hóa - Dầu - Chất keo thực phẩm

8/1/2016 1 CHẤT KEO THỰC PHẨM (Food hydrocolloids) Giảng viên: Mạc Xuân Hòa 1 NỘI DUNG 1. Giới thiệu chung về chất keo 2. Một số chất keo sử dụng làm phụ gia TP 3. Modification 2 8/1/2016 2 NỘI DUNG 1. Giới thiệu chung về chất keo 2. Một số chất keo sử dụng làm phụ gia TP 3. Modification 3 Hydrocolloids  Hydrocolloids are a heterogeneous group of long chain polymers (polysaccharides and proteins) characterised by their property of forming viscous dispersions and/or gels when dispersed in water.  The foremost reason behind the ample use of hydrocolloids in foods is their ability to modify the rheology of food system. This includes two basic properties of food system namely, flow behaviour (viscosity) and mechanical solid property (texture)  to modify its sensory properties. 4 8/1/2016 3 Kích thước cấu tử hòa tan Dung dịch 1 pha (<10-6 mm ) Dung dịch keo (10-4 - 10-6 mm ) Huyền phù (1 - 10-2 mm ) pH Nhiệt độ Lực ion, Đông tụ 5 Nguồn gốc 6 8/1/2016 4 Functional properties • Thickening (basic) • Gelling (basic) • Emulsifying • Controlling the crystal growth of ice and sugar • . 7 NỘI DUNG 1. Giới thiệu chung về chất keo 2. Một số chất keo sử dụng làm phụ gia TP 8  Thickening agent/Thickener  Gelling agent 8/1/2016 5 NỘI DUNG 1. Giới thiệu chung về chất keo 2. Một số chất keo sử dụng làm phụ gia TP 9  Thickening agent/Thickener  Gelling agent Thickening agents  A thickening agent or thickener is a substance which can increase the viscosity of a liquid without substantially changing its other properties. 10 8/1/2016 6 Examples of food products containing hydrocolloids 11 Soups GraviesSalad dressings Sauces Toppings Process of thickening In dilute dispersion, the individual molecules of hydrocolloids can move freely and do not exhibit thickening. In concentrated system, these molecules begin to come into contact with one another; thus, the movement of molecules becomes restricted. The transition from free moving molecules to an entangled network is the process of thickening. 12 8/1/2016 7 Factors effecting thickening properties  Molecular weight  Concentration  Shear rate  Temperature, 13 14  M: the molecular weight  K, α: the parameters of Mark-Houwink equation Mark-Houwink equation 8/1/2016 8 15 The critical overlap concentration C*  The polysaccharide concentration at which the sharp change in viscosity occurs is referred to as the critical overlap concentration and is denoted by C*.  Polysaccharide dispersions below C* will typically exhibit near Newtonian steady shear flow and the increase in the viscosity of the dispersion is roughly proportional to the number of molecules present. Above C* entanglement dispersion networks will exhibit shear thinning meaning that apparent viscosity decreases with increasing shear rate. 16 8/1/2016 9 Khi C>C* độ nhớt (viscosity) và tốc độ cắt (shear rate) có quan hệ như dạng đường cong ở trên. 17 Shear thining 18 At low shear rates, solutions of xanthan gum have approximately 15 times the viscosity of guar gum and significantly more viscosity than carboxymethylcellulose (CMC) or sodium alginate which accounts for its superior performance in stabilising suspensions. 8/1/2016 10 Amylose will have a higher intrinsic viscosity than amylopectin. 19 20 8/1/2016 11 21 Regulations 22 8/1/2016 12 Xanthan Gum (E415) 23 XANTHAN GUM  Nguồn gốc  Cấu tạo hóa học  Tính chất  Ứng dụng 24 8/1/2016 13 XANTHAN GUM  Nguồn gốc  Cấu tạo hóa học  Tính chất  Ứng dụng 25 26 Nguồn gốcXANTHAN GUM  An extracellular polysaccharide secreted by the bacterium Xanthomonas campestris.  Xanthan gum is produced from a pure culture of the bacterium by an aerobic, submerged fermentation process. 8/1/2016 14 XANTHAN GUM  Nguồn gốc  Cấu tạo hóa học  Tính chất  Ứng dụng 27 28 Cấu tạo hóa họcXANTHAN GUM Xanthan gum is a linear (1  4) linked β – D - glucose backbone (as in cellulose) with a trisaccharide side chain on every other glucose at C-3, containing a glucuronic acid residue linked (14) to a terminal mannose unit and (12) to a second mannose that connects to the backbone. 8/1/2016 15 XANTHAN GUM  Nguồn gốc  Cấu tạo hóa học  Tính chất  Ứng dụng 29 30 Tính chấtXANTHAN GUM Xanthan gum is widely used as a rheology control agent for aqueous systems: Increasing viscosity (thickening)  Stabilizing emulsions  Preventing the settling of solids 8/1/2016 16 31 Tính chấtXANTHAN GUM  The viscosity and yield value of compositions containing the gum will not change significantly between ambient temperature and 60°C.  Xanthan gum provides the same thickening, stabilizing and suspending properties during long-term storage at elevated temperature as it does at ambient conditions.  It imparts excellent freeze/thaw stability to most compositions. 32 Tính chấtXANTHAN GUM Complex aggregates, with weak intermolecular forces  High viscosity at low shear rates (suspension stabilising properties) 8/1/2016 17 33 At low shear rates, solutions of xanthan gum have approximately 15 times the viscosity of guar gum and significantly more viscosity than carboxymethylcellulose (CMC) or sodium alginate which accounts for its superior performance in stabilising suspensions. Tính chấtXANTHAN GUM 34 Tính chấtXANTHAN GUM 8/1/2016 18 35 Tính chấtXANTHAN GUM The viscosity remains nearly constant between pH 2 and pH 12 36 Tính chấtXANTHAN GUM Synergistic Effect Xanthan gum có có hiệu ứng “hiệp đồng” với các chất keo sau:  Guar gum  Locust bean gum  Cassia gum  Konjac mannan  Tăng khả năng làm dày 8/1/2016 19 XANTHAN GUM  Nguồn gốc  Cấu tạo hóa học  Tính chất  Ứng dụng 37 38 Ứng dụngXANTHAN GUM 8/1/2016 20 Introduction • Stabilizer gums are used to improve the texture, increase the firmness and prevent syneresis in yogurt. This is important to help maintain good textural and visual properties during transportation and storage. 39 Introduction Xanthan is used widely in the food industry because it has:  Solubility in hot or cold water,  High viscosity at low concentrations,  Little variation in viscosity with changing temperature,  Excellent solubility and stability in an acid system,  Unique rheological properties that provide high viscosity under low shear and low viscosity under high shear,  Excellent compatibility with a wide range of salts, 40 8/1/2016 21 Objectives • To determine the influence of laboratory- produced xanthan gum either singly or in combination with other gums on the rheological properties of yogurt and soy yogurt during refrigerated storage. 41 Method: Preparation of yogurt 42 Cow's milk Treat ment I 0.005% All treatments were heated to 90 °C for 10 min and rapidly cooled to 42 °C, inoculated with 2% yogurt starter, and were then distributed into 120 ml plastic cups and incubated at 42 °C until a uniform coagulum was reached (3 - 5h depending on the type of milk). The yogurt and soy yogurt cups were then transferred to refrigerated storage and analyzed after 1, 5 and 10 days of storage for their chemical, microbiological, rheological, microstructural and sensory properties. Treat ment II Treat ment III Treat ment I 0.01%Treat ment II Treat ment III Soy milk Treat ment I 0.005%Treat ment II Treat ment III Treat ment I 0.007%Treat ment II Treat ment III Treat ment I: Xanthan gum Treatment II: Xanthan gum + CMC Treatment III: Xanthan gum + locust bean gum + guar gum 8/1/2016 22 Method: Rheological properties • Viscosity: 43 Method: Rheological properties • Curd tension: 44 8/1/2016 23 Method: Rheological properties • Syneresis: 45 Syneresis of yogurt and soy yogurt was determined by measuring the volume of separated whey (milliliters whey/50 g yogurt). The amount of free whey collected after 30 min at room temperature (25±1 °C) was taken as the index of syneresis.  The viscosity values of cows’ milk yogurt or soy milk yogurt during the fermentation period were affected by the type and concentration of stabilizer used.  These values increased markedly using gum either singly or in combination with other gums. 46 Results: Viscosity of yogurt and soy yogurt during fermentation 8/1/2016 24 Results: Viscosity of yogurt and soy yogurt during fermentation 47 Results: Curd tension • The use of xanthan gum or its mixtures at mentioned concentration rates markedly increased the curd tension of yogurt as compared to the control when fresh and during storage. This increase may be attributed to the interaction between the gum and the milk portion. • Yogurt: treatment (I) with xanthan gum at a concentration of 0.01% exhibited the highest curd tension. • Soy yogurt: the addition of xanthan gum at a concentration of 0.005% (Treatment I) resulted in the highest curd tension of soy yogurt 48 8/1/2016 25 Results: Syneresis • No syneresis was found with xanthan gum at a concentration of 0.005% when fresh or during storage (in both yogurt and soy yogurt). 50 8/1/2016 26 NỘI DUNG 1. Giới thiệu chung về chất keo 2. Một số chất keo sử dụng làm phụ gia TP 52  Thickening agent/Thickener  Gelling agent 8/1/2016 27 Gels are  A three-dimensional network that traps or immobilizes water within it to form a rigid structure 53 Gels are  A form of matter intermediate between solid and liquid and show mechanical rigidity.  A viscoelastic system with a ‘storage modulus’ (G′) larger than the ‘loss modulus’ (G″). 54 8/1/2016 28 Rheology of gels 55 What is  ? Phase angle Solid-like Fluid-like Deformation tests: Oscillatory rheometer 56 8/1/2016 29 57   = 0  tan = 0: G” = 0  Solid   = /2  tan = : G’ = 0  Fluid  0 <  < /2  0 < tan <   Viscoelastic material  Gel is a viscoelastic material with G’ > G’’  We can measure G’ and G’’ by using a Oscillatory rheometer 58 8/1/2016 30 Silly putty 59 60 8/1/2016 31 Which one is stronger ? 61 62 Which one is stronger ? 8/1/2016 32 Process of gelling • The formation of gel is the phenomenon involving the association of the polymer chains to form a three-dimensional network that traps or immobilizes water within it to form a rigid structure. 63 Process of gelling: physical association  Hydrogen bonding  Hydrophobic association  Cation mediated cross-linking 64 Junction zones 8/1/2016 33 Process of gelling: ‘junction zones’ 65 • Type of hydrocolloids • Concentration of Gelling Agent • Conditions at which “junction zones” can be formed: temperature, ionic strength, high pressure, 66 CONDITIONS OF GEL FORMATION 8/1/2016 34 Type and Concentration of hydrocolloids • Not all hydrocolloids can form gel. Gel formation only occurs above a critical minimum concentration, C∗. 67 Conditions at which “junction zones” can be formed:  Temperature (low or high): agar, gelatin,..  Ionic strength: alginate, LM pectin, or carrageenan,..  pH: HM pectin  High pressure 68 8/1/2016 35 Conditions at which “junction zones” can be formed:  Temperature: agar, gelatin,..  Ionic strength: alginate, pectin, or carrageenan,..  pH  Pressure 69 70 Một số loại chất keo tạo gel khi làm lạnh (agar, gelatin, pectin, tinh bột,) 8/1/2016 36 Thermoreversible gels: agar, gelatin, 71 72 GELATIN Cooling Sol Heating (35–40ºC): ‘melt in the mouth’ 8/1/2016 37 AGAR Gelling temperature: around 380C Melting temperature: around 850C Gelling concentration: between 0,5 – 2% 73 Conditions at which “junction zones” can be formed:  Temperature: agar, gelatin,..  Ionic strength: alginate, pectin, or carrageenan,..  pH  Pressure 74 8/1/2016 38 75 Low Methoxyl Pectin DUNG DỊCH GEL Ca2+ 76 Alginate gel formation 8/1/2016 39 Conditions at which “junction zones” can be formed:  Temperature: agar, gelatin,..  Ionic strength: alginate, pectin, or carrageenan,..  pH  Pressure 77 78 High Methoxyl Pectin DUNG DỊCH GEL (hydrogen bonds) 65% chất khô H+ [Pectin] = 0,5-1%  Đường có khả năng hút ẩm  giảm mức độ hydrat hóa của phân tử pectin trong dung dịch;  H+ trung hòa bớt các gốc COO-  làm giảm độ tích điện của các phân tử; 8/1/2016 40 79 Making Jam Cooling Conditions at which “junction zones” can be formed:  Temperature: agar, gelatin,..  Ionic strength: alginate, pectin, or carrageenan,..  pH  High pressure (a single process or in combination with increased temperature): usually applied to form protein gels 80 8/1/2016 41 81 Keywords  Rapeseed  Protein isolate 82 Bodybuilder 8/1/2016 42 Introduction • Heat and high pressure can improve gelation propertie of food protein: increased exposure of hydrophobic and sulfhydryl (SH) groups (structure modification). 83 Introduction 84 • The effect of high pressure-induced modification depends on the protein system, the treatment temperature, the protein solution conditions, and the magnitude and duration of the applied pressure. 8/1/2016 43 Introduction • The objectives of this study are to determine the effects of high temperature or HP processing on protein gelation with relationships to free sulfhydryl content, surface hydrophobicity, 85 Method: HP and Heat Processing 86  1 % (w/v) RPI slurry was prepared in 50mMTris– HCl buffer (pH 7.5) with stirring at 4 °C for 12 h.  For HP treatment, the RPI slurrywas sealed in a polyethylene bag and then subjected to a 4-l HP reactor unit equipped with temperature and pressure regulation as transmitting medium of water, followed by freeze-drying and storage at −20 °C until needed for further analysis. 8/1/2016 44 Method: Design of experiment • Trial 1: HP was operated at 200, 400, and 600 MPa for 15 min each while the temperature was kept at 25 °C. • Trial 2: the RPI slurry was heated in a water bath at 60, 80, and 100 °C for 15 min. 87 Method: Determination of responses  Free Sulfhydryl Content (M/g protein)  Surface Hydrophobicity (So)  Gelation properties: least gelation concentration (LGC), Hardness (N), . 88 8/1/2016 45 Results: Free Sulfhydryl Content (M/g protein) 89 200 MPa: a significant (p<0.05) increase, which probably reflects pressureinduced exposure of inaccessible thiol groups buried within the hydrophobic interior. 400 – 600 MPa: a progressive decrease in free SH groups, which may be due to formation of disulfide bonds as pressure-induced protein– protein interactions intensified. Heat had stronger effects on Free Sulfhydryl Content when compared to HP treatments 90 Results: Surface Hydrophobicity (So) So of RPI was significantly (p<0.05) increased following HP and thermal treatments, which suggests that the native protein had a higher degree of globular (folded) structure when compared to the treated samples. The higher protein unfolding efficiency of HP treatment may be due to the effective ability to disrupt hydrogen bonds that hold proteins in a folded state. HP had a stronger effect on Surface Hydrophobicity (So) when compared to Heat. 8/1/2016 46 91 Results: Gelation properties LGC of RPI was significantly (p<0.05) decreased from 15 to 6 % by HP treatment, while heat treatment decreased LGC from 15 to 10 %. The unfolded proteins are then able to interact through hydrophobic bonding to increase strength of resultant gel networks and reduce amount of proteins required to form the gel, i.e., decreased LGC. Conclusions • Overall, pressure treatments (200–600 MPa) were better than heat treatments (60–100 °C) to modify the structure and improve gelation properties of RPI. 92 8/1/2016 47 93 94 8/1/2016 48 95 96 Jam Jelly Confectionery 8/1/2016 49 97 98 8/1/2016 50 Other Applications  Surface activity and emulsifying properties  Hydrocolloids as edible films and coatings  Hydrocolloids as fat replacers 99 100 8/1/2016 51 NỘI DUNG 1. Giới thiệu chung về chất keo 2. Một số chất keo sử dụng làm phụ gia TP 3. Modification 101 Why do we modify food hydrocolloids ? • Some native hydrocolloids have often been reported to present a number of undesired properties, including is insolubility in cold water, crumbling after heating, and loss of viscosity, 102 8/1/2016 52 Starch 103 Cấu tạo hóa họcTINH BỘT Hydrogen bonds 104 8/1/2016 53 Rheological propertiesSTARCH Heating Cooling Reassociation of Amylose 105 Three categories of digestible starches are distinguished by the rate at which glucose is formed and absorbed in the blood  Rapidly digestible starches (RDS) are hydrolysed in the small intestine within the first 20 min of digestion.  Slowly digestible starches (SDS) acquire more time to degrade.  Resistant starch (RS) generally escapes digestion in the small intestine and passes through the large intestine as dietary fiber for fermentation by bacteria, where it helps to maintain colon health and protect against disease 106 8/1/2016 54 Starch modificatiion • Starch modifications are a means of altering the structure and affecting the hydrogen bonding in a controllable manner to enhance and extend their application. The alterations take place at the molecular level, with little or no change taking place in the superficial appearance of the granule. Therefore, the botanical origin of the starch may still be identified microscopically 107 108 Hạt tinh bột khoai tây ở thời điểm trước và sau biến tính bằng enzyme amylase 8/1/2016 55 Biến tính tinh bột (Starch modification) TINH BỘT  Phương pháp vật lý  Phương pháp hóa học  Phương pháp hóa sinh (enzyme) 109 Biến tính tinh bột (Starch modification) TINH BỘT  Phương pháp vật lý  Phương pháp hóa học  Phương pháp hóa sinh (enzyme) 110 8/1/2016 56 Biến tính tinh bột (Starch modification) TINH BỘT Phương pháp vật lý: Tiền hồ hóa (Pre-gelatinisation)  Mục đích: pregelatinisation is designed to remove the necessity for cooking.  Phương pháp: tinh bột ban đầu được hồ hóa trong một lượng thừa nước, sau đó sấy để tách ẩm. 111 Drum Drying 112 8/1/2016 57 113 Production of pre-gelatinized wheat starch Wheat starch was first dispersed in cold water (10% w/w, starch in water), then, it was dried using a twin drum drier (Model Benton Harbor, USA) at drum speed of 5 rpm, steam pressure of 5 bar, clearance between the drums of 0.4 mm and the surface temperature was 158 °C. The dried starch sheet with moisture content of 7.3% ± 0.2 (dry weight basis) was milled using a laboratory mill and then sieved to obtain a powder with particle size of 150-250 μm. The PGS was packed in polyethylene bags and stored at room temperature for further experiments. 114 8/1/2016 58 115 Twin Drum Drier 116 Pre-gelatinized Wheat Starch 8/1/2016 59 117 Pre-gelatinized Wheat Starch 118 Pre-gelatinized Wheat Starch A cold water viscosity of 3833 centi Poise (cP) was observed for PGS at 25 ºC, while no peak was seen for the native starch at this temperature. For the latter, a peak viscosity of 2011 cP was observed at 95 ºC when the sample was held for 11 min. 8/1/2016 60  The PGS had the ability to increase the viscosity at temperatures below gelatinization temperature of native starch. At high temperatures, however, the native starch was able to increase the viscosity.  Moreover, if PGS is heated and then cooled down, it produces lower final viscosity than native starch. 119 Pre-gelatinized Wheat Starch 120 8/1/2016 61 Keywords Imitation cheese 121 Keywords Imitation cheese 122 Imitation (analogue) cheese products may be classifed as cheese substitutes or imitations, which partly or wholly substitute or imitate cheese and in which milk fat, milk protein or both are partially or wholly replaced by non-milk-based components, principally of vegetable origin. Ingredients such as rennet casein, vegetable oils or fats, salts, acids and Xavourings are generally used in the manufacture of imitation cheese. Rennet casein: Due to its high cost, considerable eVort has been vested in the partial replacement of casein with cheaper ingredients, of which, starch has been the most effective low-cost casein substitute 8/1/2016 62 Objectives • The objective of this study is to investigate the eVects of pre-gelatinised starches on the rheology, meltability and microstructure of imitation cheese. 123 Materials & methods: imitation cheese Water 48% Renet casein/PG starch 24.5% Vegetable fat 26% Emusifying salt (trisodium citrate, citric acid, disodium phosphate) 2.18% Sodium chloride 1.67% Sorbic acid 0.1% 8/1/2016 63 Control PG maize PG waxy maize PG wheat PG potato PG rice Rennet casein replacing 15% of the rennet casein by PGS  Micro-structure  Melt  Hardness  Dynamic rheology  Viscosity Results 126 8/1/2016 64 Micro - structure PGS had poorer fat emulsification. Imitation cheese products containing pre-gelatinized starches had larger fat globule size distributions (especially rice or waxy-maize starch). 128 8/1/2016 65 129 The G’ of all products decreased signiWcantly (P · 0.05) with increasing measuring temperature from 22 to 85 °C, due to melting of the vegetable fat and softening of the protein matrix. Imitation cheese containing potato starch had the highest G’ values in the temperature ranges 55–85 °C, which was possibly due to extensive starch retrogradation impeding the Xow of casein. 130 All products containing starch had significantly lower tan values at 22 °C (ranging from 0.36 - 0.02 for waxy-maize to 0.42 - 0.013 for rice starch- containing imitation cheese) compared to the control imitation cheese (0.44 - 0.012), indicating more elastic (less viscoelastic) structural behaviour compared to the control. 8/1/2016 66 The replacement of 15% of the protein in the dispersions with pre-gelatinised starches resulted in increases in apparent viscosity in the order rice starch (26.3 - 1.2 mPa s) > waxy-maize (24.6 - 0.4 mPa s) > wheat (22.2 - 0.5 mPa s) > potato (21.6 - 0.6 mPa s) > maize (20.0 - 0.5 mPa s) starch. 131 Biến tính tinh bột (Starch modification) TINH BỘT  Phương pháp vật lý  Phương pháp hóa học  Phương pháp hóa sinh (enzyme) 132 8/1/2016 67 Biến tính tinh bột (Starch modification) TINH BỘT Phương pháp hóa học:  Acid hydrolysis  Oxidation  Cross-linking  Stabilisation  Lipophilic substitution  Dextrinisation 133 Biến tính tinh bột (Starch modification) TINH BỘT Phương pháp hóa học: Acid hydrolysis  When the starch is heated beyond its gelatinisation temperature the granules rupture quickly.  A lower hot viscosity due to the increase in the ratio of smaller, linear molecules  A stronger gel develops on cooling (set-back) Water/alcol 134 8/1/2016 68 Biến tính tinh bột (Starch modification) TINH BỘT Phương pháp hóa học: Oxidation Alkaline hypochlorite  The relatively bulky carboxyl (COOH) and carbonyl (C=O) groups are introduced together  the bulky groups disrupts any tendency towards re-association (set back) of the shorter chains reduce the gel strength.  Partial depolymerisation of the starch chains  a significantly reduced hot viscosity.  Bleaching 135 136  Độ nhớt khi hạt tinh trương nở cực đại  Tính bền nhiệt: sự thay đổi độ nhớt ở nhiệt độ cao  Tốc độ hồ hóa  Độ bền gel: độ nhớt khi tạo gel 8/1/2016 69 Biến tính tinh bột (Starch modification) TINH BỘT Phương pháp hóa học: Cross - linking Distarch phosphates Distarch adipates Cross – linking Replacement of the hydrogen bonding between starch chains by stronger, more permanent, covalent bonds: typically one cross-link per 100–3000 anhydroglucose units of the starch:  The swelling of the starch granule is inhibited;  The starch becomes more resistant to gelatinisation;  Heat and shear stability over their parent native starches. 137 138 8/1/2016 70 139 acetate-adipate starch. distarch phosphate Biến tính tinh bột (Starch modification) TINH BỘT Stabilisation Phương pháp hóa học: 140  Bulky groups are substituted onto the starch to take up space and hinder (steric hindrance) any tendency for dispersed (cooked), linear fragments to re-align and retrograde (freezethaw cycles).  Degree of Substitution (DS): is a measure of the number of substituents per 100 anhydroglucose units (those with DS below 0.2 are typically used).  Easy cooking, particularly useful in low-moisture environments and where the moisture level is restricted by competition from co- ingredients. Acetylated Hydroxypropylated 8/1/2016 71 141 E1420: acetylated starch  Độ nhớt khi hạt tinh trương nở cực đại  Tính bền nhiệt: sự thay đổi độ nhớt ở nhiệt độ cao  Tốc độ hồ hóa  Độ bền gel: độ nhớt khi tạo gel 142 Biến tính tinh bột (Starch modification) TINH BỘT Lipophilic substitution Phương pháp hóa học: Hydrocarbon chain The glucose part of starch binds the water while the lipophilic part binds the oil  emulsion stabilisation. 8/1/2016 72 143 Biến tính tinh bột (Starch modification) TINH BỘT Dextrinisation Phương pháp hóa học:  (a) Depolymerisation: dry roasting the starch either alone, making use of its natural 10–20% moisture content, or in the presence of catalytic quantities of acid.  (b) Recombination: in a branched manner. (a) (b) Biến tính tinh bột (Starch modification) TINH BỘT Combination treatments are used to achieve the desired objective: Cross-linking/Stabilisation Cross-linking/Stabilisation/Pregelatinisation 144 8/1/2016 73 145  Độ nhớt khi hạt tinh trương nở cực đại  sự thay đổi độ nhớt ở nhiệt độ cao  Tốc độ hồ hóa  Độ bền gel: độ nhớt khi tạo gel 146 E1412: distarch phosphate (Cross-linking) E1414: acetylated distarch phosphate (Cross-linking/Stabilisation) E1422: acetylated distarch adipate (Cross-linking/Stabilisation)  Độ nhớt khi hạt tinh trương nở cực đại  Tính bền nhiệt: sự thay đổi độ nhớt ở nhiệt độ cao  Tốc độ hồ hóa  Độ bền gel: độ nhớt khi tạo gel 8/1/2016 74 Biến tính tinh bột (Starch modification) TINH BỘT  Phương pháp vật lý  Phương pháp hóa học  Phương pháp hóa sinh 147 Biến tính tinh bột (Starch modification) TINH BỘT Phương pháp hóa sinh 8/1/2016 75 149 Dextrose Equivalent (DE): Biến tính tinh bột (Starch modification) TINH BỘT  DE = 100: dextrose (glucose)  DE = 0: starch  DE = 50: maltose  DE < 20: maltodextrin  DE = 20 ÷ 100: glucose syrup Phương pháp hóa sinh Bai bao dual starch 150 8/1/2016 76 151