Food Science deals with the production, distribution, preparation and evaluation of food., Schemes and Mind Maps of Food Process Engineering

Download Food Science deals with the production, distribution, preparation and evaluation of food. and more Schemes and Mind Maps Food Process Engineering in PDF only on Docsity! Course outline  Introduction Macronutrient Water in a food system Lipid/fat Protein Carbohydrate yyyy Cont. Micronutrient Vitamins, Enzymes, Minerals Food additives Antioxidants, Sweating substances, Emulgators, Conserving sub, Color, thikning sub. Cont. Its cost Quality Processing Safety nutrition value Whole sameness and convenience. Cont’d  Food Science deals with the production, distribution, preparation, evaluation, and utilization of food. Food chemists work with plants that have been harvested for food, and animals that have been slaughtered for food. Cont.d Food chemists are concerned with how these food products are processed, prepared, and distributed. For example, to address consumer demands, some food chemists are involved with finding fat and sugar substitutes that do not alter food taste and texture Develop and understanding of how individual components contributes to the overall quality of foods. Achieve an understanding of the chemical changes that take place with food components during processing and storage. Cont.  To develop a successful food product one needs a basic understanding on how ingredients work chemically and how they interact with each other  Shelf stability  Appearance  Texture  Taste  Nutrition If one fails the whole product can fail Cont. Food chemists work with biological systems that are dead or dying (post-harvested plants and postmortem animal tissues) and study the changes they undergo when exposed to different environmental conditions.  For example, during the marketing of fresh tomatoes, the food chemist must determine the optimal conditions to sustain the residual life in the tomatoes so the tomatoes will continue to ripen and arrive at the supermarket as a high-quality product for the consumer. Cont. The study of food science / chemistry also includes biotechnology, which is the use of biological processes to make new foods, enzymes, supplements, drugs, and vaccines. For thousands of years, people have been using microorganisms in the fermentation of beer and in the making of cheeses, wines, and breads. Today biotechnology also encompasses genetically engineered foods. In genetic engineering, scientists splice (join) genetic material from plants, animals, or bacteria and insert this genetic material in to the DNA of other organisms. These new organisms are called genetically modified organisms (GMOs). Quality and safety attributes  Safety is the first requisite of any food in a broad sense, this means a food must be free of any harmful chemical or microbial contaminate at the time of its consumption. E.g. In the canning industry commercial sterility means the absence of viable spores of clostridium botulinum. This can be translated in to a specific set of heating conditions for a specific product in a specific package. These heating requirements, can then select specific time - temp. conditions that will optimize retention of quality attributes.  In peanut butter, operational safety can be regarded primarily as the absence of aflatoxins –carcinogenic substances produced by certain spices of moldes Cont.  In fabricated foods, the comp. can be controlled by adding approved chemicals, such as Acidulates, chelating agents, flavors, or antioxidants, or by removing undesirable reactants.  Composition of the atmosphere is important mainly with respect to relative humidity and oxygen content.  The consequences of a small amount of residual oxygen sometimes become apparent during product storage e.g. early formation of a small amount of dehydro-ascorbic acid (from oxidation of ascorbic acid) can lead to Millard browning during storage.  Some products must not exposure to light during packaging Cont.  Food chemists must be able to integrate information about quality attributes of foods, deteriorative reactions to which foods are susceptible, and the factors governing kinds and rates of these deteriorative reactions, in order to solve problems related to food formulation, processing, and storage stability.  To day, with nation wide industries and with the growth of a consumer market which expects and demands a uniform product, it is necessary to control processes carefully.  This control demands understanding of the process, some industries have been very active in attempting to develop a scientific basis for their procedures Cont. The water content or the moisture content of a food influences its appearance, texture and flavor.  It varies a great deal in different food items. Products                 Water (%) Green leaves 95 Tomato 95 Watermelon 93 Orange 87 Potato 78 Banana 75 Butter 16 Rice 12 Legumes (dry) 9-11 Types of Water in Foods Water in foods can be either in free or bound form, depending on its interaction with the surrounding molecules. The ‘bound water’ refers to water that is physically or chemically bound to food components. Many compounds like starch, proteins and some salts have water bound to them in the form of hydrates. Cont. The free water is the bulk water free from any other constituents.  It is held in narrow channels between certain food components due to capillary forces and is held trapped within the spaces in food. It is surrounded by physical barrier e.g., biological cell that prevents it from escaping.  It is actually responsible for the microbial growth and deterioration of food. It is also called the available water. This free /unbound /available water is expressed in terms of water activity. Moisture Content The moisture content of a food item is defined as the amount of water lost per gram of the food product at about 100o C. Though important, water content or % moisture is not a reliable predictor of microbial responses and chemical reactions in food products.  The water content of a safe product varies from product to product and from formulation to formulation. One safe, stable product might have a water content of 15% while another with a water content of just 8 % is susceptible to microbial growth. This is so because the microbial stability or physicochemical properties of food are often determined by amount of free water Present rather than the total amount of water Cont. Reducing the amount of free--or unbound--water also minimizes other undesirable chemical changes that occur during storage. The processes used to reduce the amount of free water in consumer products include techniques like concentration, dehydration and freeze drying. Freezing is another common approach to controlling spoilage. Water in frozen foods is in the form of ice crystals and therefore unavailable to microorganisms and for reactions with food components. Properties of water that is important to the chemistry of life  The physical properties of water allow it to act as a solvent for ionic and other polar substances  Water molecules can form weak bonds with other compounds including other water molecules.  Water affects the interactions of substances that have low solubility in water.  The Ionization of water and its acidity and basicity are important for understanding the molecules and the metabolic processes of life.  Water molecules is polar  Water molecule has hydrogen bonding (e.g. ice). Cont. Specific heat and heat of vaporization of water are related to its hydrogen bonding. The specific heat of a substance is the amount of heat needed to raise the temperature of 1 gram of the substance by 10C The abundance of water in the cells of all organisms means that temperature fluctuations with in cells are minimized.  This feature is of critical biological importance since the rates of most biochemical reactions are sensitive to temperature. Cont.  A large amount of heat is required to evaporate water because hydrogen bonds must be broken to permit water molecules to dissociate from one another and enter the gas phase.  Because the evaporation of water absorbs so much heat, perspiration (sweating) is an effective mechanism for decreasing body temperature.  The unusual thermal properties of water make it a stable environment for living organisms as well as an excellent medium for the chemical processes of life.  Water can interact with and dissolve other polar compounds and compounds that ionize. Cont.  The solubility of organic molecules in water is determined chiefly by their polarity and their ability to form hydrogen bonds with water.  An increase in the number of polar groups, such as hydroxyl groups, in an organic molecule increases its solubility in water. • E.g. a glucose molecule is very soluble in water. Water is essential to life:- As an important governor of body temperature As a solvent As a carrier of nutrients and waste products As a reactant and reaction medium As a lubricant and plasticizer As a stabilizer of biopolymer conformation Water is the major component of many foods  Water in the proper amount, location and orientation profoundly influences the structure appearance and texture of foods and their susceptibility to spoilage.  Because most kinds of fresh foods contain large amounts of water effective forms of preservation are needed if long term storage is desired.  Removal of water, either by conventional dehydration or by separation locally in the form of pure ice crystals (freezing), greatly alters the native properties of foods and biological matter,. Cont.  Furthermore , all attempts (rehydration, thawing) to return water to its original status are never more than partially successful. Physical properties of water  As there are many physical properties of water, thermal conductivity of water is large compared to those of other liquids, and the thermal conductivity of ice is moderately large compared to those of other nonmetallic solids.  The thermal conductivity if ice at 0ºc is approximately four times that of water at the same temp., indicating that ice will conduct heat energy at a much greater rate than will immobilized water (e.g. in tissue). Determination of Moisture  Solar drying  Frizz drying  Oven drying method  Many foods decompose to some degree if they are heated to 100ºc. E.g. foods which contain fructose. It is necessary to dry them in a vacuum oven where the temperature is maintained at a lower figure and the pressure is reduced too facilitate less of moisture. Cont. The immiscible solvent distillation method. Those foods which contain volatile compounds other than water must be treated by another method.  None of the weight-loss methods are adequate to differentiate b/n loss of water and loss of some other volatile substances. The sample is placed in a flask which is connected with a reflux condenser equipped with a distillate trap. The sample is covered with a suitable solvent and the trap filled with the solvent. The solvent must be immiscible with water so that as they distill separation of the two liquids can occur.. Water activity and spoilage Cont. Most foods have a water activity above 0.95 and that will provide sufficient moisture to support the growth of bacteria, yeasts, and mold. The amount of available moisture can be reduced to a point that will inhibit the growth of microorganisms Water activity values of selected foodsFood Wat r a tivity Fresh meat and fish 0.99 Liverwurst 0.96 Bread 0.95 Cookies 0.3 Instant coffee 0.2 Predicting Food Spoilage Water activity (aw) has its most useful application in predicting the growth of bacteria, yeast, and mold.  For a food to have a useful shelf-life without relying on refrigerated storage, it is necessary to control either its acidity level (pH) or the level of water activity (aw) or a suitable combination of the two. This can effectively increase the product's stability and make it possible to predict its shelf life under known ambient storage conditions. Food can be made safe to store by lowering the water activity to a point that will not allow pathogens such as Clostridium botulinum and Staphylococcus aureus to grow in it.