Food Chemistry: Water & Ice (PDF)

FBTU1206 FOOD CHEMISTRY By : Fransisca Wijaya, MP. This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! References § Velisek J. 2014. The Chemistry of Food....

FBTU1206 FOOD CHEMISTRY By : Fransisca Wijaya, MP. This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! References § Velisek J. 2014. The Chemistry of Food. John Wiley & Sons, Ltd. § S. Damodaran, K.L. Parkin, and O. R. Fennema (Eds.). 2017. Food Chemistry, 5th edition. CRC Press. § Belitz H-D et al. 2009. Food Chemistry, 4th Ed. Springer-Verlag: Berlin. § CEK E-BOOK! This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Silahkan scan dan dijawab This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  01 What is Food Chemistry? This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! What is food chemistry? Why and how? This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Introduction What is food chemistry? § Food chemistry deals not only with the composition of food raw materials and end food products, but also with the behaviour, interactions and reactions of food components and the changes occuring in these food raw materials and end food products under various conditions during production, storage, processing, preparing and cooking. § Minor areas: Biochemistry, chemical engineering, nutritional biochemistry, organic chemistry, physical chemistry, toxicology, and analytical chemistry This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Introduction What is food (2) determining those chemistry? 1) determining those chemical and biochemical reactions that have properties that are important characteristics of important influences on loss safe, high quality foods of quality and/or § An analytical wholesomeness of foods approach to food (3) integrating the first two (4) applying this chemistry points so that one understanding to various includes four understands how the key situations encountered components, chemical and biochemical during formulation, namely : reactions influence quality processing and storage of and safety food. This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Learning Objectives 07 Understand the microbiologic 05 al growth and food shelf life Understand Explain the moisture role of water 03 content, activity in water chemical activity, and reaction moisture sorption Understand isotherm the chemical Classify types 01 structure and of water in 06 physicochemi foods cal properties of water and Explain what Understand ice food the role of chemistry is water in 04 and explain foods the scope of food chemistry 02 This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Food composition/component Macronutrient Micronutrient Water Vitamins Carbohydrates Minerals Proteins Food Additives Lipids/ Fats This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  Water & Ice This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! 02 Understand the role of water in foods This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water in food Water content Water content Food Food (%) (%) Tomato 94 Dried fish 38 Watermelon 93 Beef 66 Cabbage 92 Bread 36 Pineapple 85 Dried fruits 28 Mungbean 88 Milk powder 14 Bovine milk 90 Wheat flour 12 This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water in food § Affect texture, freshness, and shelf life § Universal solvent (salt, vitamins, sugar, pigments) § Can ionize (H3O+, OH-) § Important for enzymatic activities § Microorganisms’ growth à determine food safety & stability § Heat transfer medium § No calories § Involved in chemical reactions This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  Involved in chemical reactions Dehydration Reaction in the Synthesis of a Polymer This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Involved in chemical reactions Hydrolysis Reaction of a Polymer This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  Involved in chemical reactions Water involvement in starch-glucose polymerization This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  Involved in chemical reactions Water involvement in lipid synthesis This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  Involved in chemical reactions Water involvement in peptide synthesis This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! 03 Understand the chemical structure and physicochemical properties of water and ice This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water molecule Rumus molekul: H2O § Atom H dan O dihubungkan dengan ikatan kovalen § Bersifat polar: § H cenderung bermuatan positif (d+) § O cenderung bermuatan negatif (d-) This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water molecule Water is a "polar" molecule, meaning that there is an uneven distribution of electron density. Water has a partial negative charge near the oxygen atom due the unshared pairs of electrons, and partial positive charges near the hydrogen atoms. An electrostatic attraction between the partial positive charge near the hydrogen atoms and the partial negative charge near the oxygen results in the formation of a hydrogen bond. The ability of ions and other molecules to dissolve in water is due to polarity. Example, sodium chloride in its crystalline form dissolves in water. This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water molecule This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Physical properties of water v The bond is formed due to the affinity of electro-positive hydrogen atoms for electro-negative atoms such as O. v H-bond results in the high boiling point of water and water flowability. High heat of vaporization Strong surface tension High specific heat H – bond Nearly universal solvent Energy of H-bond = 10% of covalent bond (10 kcal/mol) The H-bond results in high Tboil of water (100oC) at 1 atm This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Physical properties of water At 1 atm (atmospheric pressure): § Liquid (T > 0oC) § Solid/ ice (T = 0oC) à Freezing point § Gas (T = 100oC) à Boiling point § Density = 1 g/ml This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Physicochemical properties Physical Constants Molecular weight 18.0153 Melting point at 1 atm 0.0oC Boiling point at 1 atm 100oC Heat of fusion at 0oC 6.012 kJ (1.436 kcal)/mol Phase transition properties Heat of vaporization at 100oC 40.657 kJ (9.711 kcal)/mol Heat of sublimation at 0oC 50.91 kJ (12.16 kcal)/mol This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! pH value of water and water containing components This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water in food Sifat koligatif : sifat pelarut (air) dipengaruhi oleh interaksi dengan zat terlarut Tekanan uap ↓ Titik beku ↓ Titik didih & tekanan osmotik This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  Dispersion Systems Solution : Suspension: Colloid : Salt/Sugar in water flour in water Milk This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  The effect of dispersed particles on the colligative properties in different dispersion systems Colligative Effect of Dispersed Particles Property Solutions Colloids Suspensions Boiling Point Freezing Point slightly affected no affect of significantly affected by by dispersed dispersed Water Activity solute particle particle Osmosis This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Phase changes of water § Affected by atmospheric pressure § At standard/normal condition (1 atm): freezing point(0oC), boiling point (100oC) § Other condition: P< 1 atm: Tboil < 100oC; Tfreeze > 0oC P> 1 atm: Tboil > 100oC, Tfreeze < 0oC This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Phase Diagram of H2O 375oC 218 atm Titik Beku Mendidih Kondensasi 1 atm Cair Gas Tekanan Padat 0.0098oC 4.6 Torr 0.0061atm Triple point Sublimasi Deposisi 0 Suhu (oC) 100 (Tb) (Td) This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  375oC 218 atm Critical point adalah sebuah titik yang menjadi batas akhir dari kurva ekuilibrium fase cair dan gas sehingga dapat berada pada satu kondisi tekanan dan temperatur yang sama. 0.0098oC 4.6 Torr 0.0061atm This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  Freeze drying??? Ø Suhu produk diturunkan sehingga air membeku. Ø Tekanan diturunkan sehingga dapat menye-babkan sublimasi es menjadi uap. This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Drying This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Physical properties of ice § Structure: Hexagonal (1 H2O molecule binds 4 other H2O molecule in the vicinity) § Density: 0.92 g/ml (floating on water) This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  04 Classify types of water in foods This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Types of water Water is not evenly distributed in food. They can have different degree of binding with other molecule of food matrix. 1. Type 1 § The real bound water § Bound to other molecules by hydrogen bond § Forms hydrate with other molecules, e.g. protein, carbohydrates, lipids. § Cannot freeze 2. Type 2 § Forms hydrogen bond with other molecules, trapped in microcapillar of food (Monolayer water) § Different properties from pure water § Water that is tied up by the presence of soluble solids § More difficult to remove than free water This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Types of water (cont’d) 3. Type 3 § Physically bound in matrix tissue of food, such as membrane, capillary, fiber, etc § Act as free water § Easily removed § Can be used for biological & chemical reaction § Responsible for the humidity of food § Water from which water activity is measured 4. Type 4 § Free/ mobile water § Easily removed § Can be used for biological & chemical reaction This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  05 Understand moisture content, water activity, and moisture sorption isotherm This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Discuss! § Apa bedanya aktivitas air dan kadar air? § Bagaimana cara mengukurnya? § Fungsi dari aktivitas air dan kadar air? § Bagaimana hubungan keduanya? This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water § Moisture content: the amount of water contained in food (%). Do not necessarily describe the biological activities. § Relative humidity (RH): the amount of water contained in the air (%). § Water activity (aw): the measure of water availability/ activity in food materials, either for chemical or biological reaction. Value: 0 – 1. Aw=1 (pure water) This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water activity § Used as criteria for determination of food safety and food quality § Water activity is better index than moisture content to address microbial or chemical activities in food. Microbes can only use free water for their growth. § Aw: 0.0 - 1.0 (no unit). § Aw=0 (absolutely dry) § Aw=1 (pure water) This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water activity § When pure water is stored in closed room, it will reach equilibrium with surrounding air (Po). § When salt solution is stored in closed room/ chamber à changes in vapor pressure (P) § Equilibrium Relative Humidity (ERH) is percentage of P and Po ratio. § When food is stored in closed chamber containing saturated salt solution, Aw and moisture content will change until equilibrium is reached. - if Aw of food > ERH, water released to air - if Aw of food < ERH, water from air will be absorbed This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water in food T Aw = ERH/100 = P/Po ERH P Where: Aw : water activity Foods ERH: equilibrium relative humidity P: vapour pressure of above sample at T Po: vapour pressure of pure water at T This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water activity Food products aw Meat, fish, fruits 0.95-1 Syrups, sweet condensed milk 0.8-0.87 Jam 0.75-0.8 Milk powder 0.2 Potato chips 0.08 This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Aw vs moisture content § Aw increase will always be followed by moisture content increase, though not linear § The relationship of Aw (or RH) with equilibrium moisture content at certain T is depicted in Moisture Sorption Isotherm (MSI): § The curve is made experimentally and mostly is sigmoidal. § Specific for each food material and depends on T § For highly hygroscopic foods, the curve is not sigmoidal as they continue absorbing water (do not reach equilibrium) This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Water activity 0.11 0.33 0.38 0.75 0.86 0.97 LiCl MgCl2 NaI NaCl K2CrO4 K2Cr2O7 § Different salt has different solubility, hence different P changes. § Food stored in different saturated salt solution will have different Aw and moisture content. § Equilibrium state will be reached when no more moisture content changes, so final Aw = ERH/100 This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Moisture sorption isotherm Zone I Zone II Zone III This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  Tipe Kurva Sorpsi Isotermis Air Zone I Zone II Zone III 1 - Highly hygroscopic Moisture Content 1 2 - Medium 2 hygroscopic 3 - Low hygroscopic, 3 sensitive to high air humidity Water Activity This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Moisture sorption isotherm § Adsorption curve: from dry to wet (e.g. rehydration) Moisture content (gH2O/g) Zone I Zone II Zone III § Desorption curve: Desorpsi from wet to dry (e.g. drying). § Adsorption and Adsorpsi desorption have different shape, known 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 as moisture sorption Aw hysteresis. This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! 06 Explain the role of water activity in chemical reaction This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Why Aw important § Affect texture (crispiness, crunchiness) - the crunching sound of breakfast cereal disappear at about Aw = 0.65 § Affect the rate of agglomeration in hygroscopic foods (easy to absorb water); e.g. milk powder § Affect chemical reaction - fat oxidation - non-enzymatic browning (Maillard reaction) - enzymatic reaction This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  Laju Reaksi pada Produk Pangan Akibat Perubahan Aktifitas Air Zone I Zone II Zone Relative Reaction Rate III Oksidasi lemak Reaksi Moisture Content hidrolisis Reaksi browning non- enzimatis Moisture sorption isotherm th gro th h Ba as row ria row wt g cte t g nzim ld s e Mo ifita Akt Ye 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Water Activity This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Fat oxidation vs Aw § At low Aw (0.4, oxidation becomes increasingly rapid. The hydration causes physical swelling of protein and carbohydrate and exposure of additional oxidizable sites, causing the increase of oxidation rates This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only!  Maillard reaction vs Aw Moisture directly impacts the Maillard reaction primarily by dissolving and/or diluting reactants. At low Aw ( 0.95 : highly perishable § Affect risk for food safety - the higher the Aw of a food, the riskier it is This material belongs to Universitas Prasetiya Mulya Do not upload and share this material to public domain. For private use only! Aw and microbial growth Most bacteria, some yeasts, pathogenic aw Fresh meat, fish, vegetables, etc. Foods with 0.86 with 15% water Most mold, no growth of pathogenic bacteria Jam, marmalade, old salami, foods with 0.80-0.87 26% (w/w) NaCl Most halophilic bacteria wth 0.75-0.80 o Flour, cereals, nuts Xerophilic mold Gr 0.65-0.75 Caramels, honey Osmophilic yeast 0.60-0.65 Breakfast cereals, snack foods, food powders No growth