1 FOOD ANALYSIS BTFT302IU PHAM VAN HUNG, PhD Department of Food Technology School of Biotechnology, IU 2 INTRODUCTION • This module is a very brief overview of common methods of food analysis used in food processing organizations. 3 WHY ANALYZE FOOD? • Government regulations require it for certain products with standards of identity (e.g.% fat and moisture in meat products). • Nutritional Labeling regulations require it. • Quality Control- monitor product quality for consistency. • Research and Development - for the development of new products and improving existing products. Food analysis is critical to ensure the food – is safe, free from harmful contaminants – is compositionally correct – contains only permitted additives – is correctly described and labeled What must a food scientist be able to do? • Know chemical properties of foods • Understand food composition and quality • Control compositional interactions • Know current analysis procedures • Select appropriate procedure for a food • Be aware of developments and changes 6 What Properties are Typically Analyzed? • Chemical Composition – water, fat, carbohydrate, protein etc • Physical Properties - Rheological or stability • Sensory Properties - Flavor, mouth-feel, color, texture etc. 7 References on Analytical Techniques • Official Methods; - Vietnamese Standards (TCVN) - Association of the Official Analytical Chemists (AOAC) - American Oil Chemists Society (AOCS) - American Association of Cereal Chemists (AACC) 8 Criteria for Selecting an Analytical Technique • There are many techniques to analyze foods but each has drawbacks or compromises. • You must select the technique that is required or fits into your system. • For example, the most accurate techniques generally take longer to perform and you may not have the time if the food product you are making requires “real time” results such as in the formulation of processed meats. 9 Criteria for Selecting an Analytical Technique • Precision • Accuracy • Reproducibility • Simplicity • Cost • Speed • Sensitivity • Specificity • Safety • Destructive/ Non- destructive • On-line/off-line • Official Approval 10 SAMPLING AND SAMPLE PREPARATION 11 What is the Purpose of the Analysis • Official Samples •Raw Materials • Process Control Samples • Finished Products 12 Sampling Plan • A sampling plan is a predetermined procedure for the selection, withdrawal, preservation, transportation and preparation of the portion to be removed from a lot as samples. • The sampling plan should be a clearly written document containing details such as; - Number of samples selected - Sample location (s). - Method of collecting samples 13 Factors Affecting a Sampling Plan • Purpose of inspection -acceptance/rejection, variability/average • Nature of the product -homogenous, unit, cost • Nature of the test method -Critical/minor, destructive, cost, time • Nature of the population -uniformity, sublot 14 Developing a Sampling Plan • Number of samples selected -Variation in properties, cost, type of analytical techniques • Sample location -random sampling vs systematic sampling vs judgment sampling • Manner in which the samples are collected -manual vs mechanical device 15 The Bottom Line in Sampling • Depending upon the nature of the material to be analyzed, you must determine a method of taking small subsamples from a large lot ( 5,000 lb blender, 20 combos on a truck etc) that accurately reflect the overall composition of the whole lot. • An inaccurate sample of a large lot may actually be worse than no sample at all. 16 Preparation of Laboratory Samples • You may have taken as much as 10 lbs of sub- samples from a lot that now needs to be further reduced in size; -Make the sample homogeneous by mixing and grinding and then more sub-sampling. -Be aware of any changes that might occur between sampling and analysis and take proper action ( e.g. enzymatic action, microbial growth etc). -Properly label the final sample with name, date/time, location, person and other pertinent data. 17 FOOD COMPONENTS • Food consists primarily of water( moisture), fat (or oil), carbohydrate, protein and ash (minerals). • Since food consists of these 5 components, it is important that we understand how these components are measured. 18 COMPOSITION OF FOODS COMPONENT Milk Beef Chicken Fish Cheese Cereal grains Potatoes Carrots Lettuce Apple Melon % Water %Carbohydrates %Protein % Fat % Min/Vit 87.3 5.0 3.5 3.5 0.7 60.0 0 17 5 22.0 0.9 66.0 0 20.2 12.6 1.0 81.8 0 16.4 0.5 1 3 37.0 2.0 25.0 31.0 5.0 10-14 58-72 8-13 2-5 0.5-3.0 78.0 18.9 2.0 0.1 1.0 88.6 9.1 1.1 0.2 1.0 94.8 2.8 1.3 0.2 0.9 84.0 15.0 0.3 0.4 0.3 92.8 6.0 0.6 0.2 0.4 19 Moisture Determination • Moisture or water is by far the most common component in foods ranging in content from 60 – 95%. • The two most common moisture considerations in foods is that of total moisture content and water activity. 20 PROTEINS • Proteins are made up of amino acids. • Amino acids are the building blocks of protein. • Nitrogen the most distinguishing element versus other food components (carbohydrates, fats etc) • Nitrogen ranges in proteins : 13.4 - 19.1% • Non-protein nitrogen: free amino acids, nucleic acids, amino sugars, some vitamins, etc. • Total organic nitrogen = protein + non-protein nitrogen 21 Types of Protein Analysis • Kjeldahl – measures the amount of nitrogen in a sample. •Lowry - measures the tyrosine/tryptophan residues of proteins. • Bradford – use Bradford reagent to determine protein content. 22 Fats • Fats refers to lipids, fats and oils. • The most distinguishing feature of fats versus other components ( carbohydrates, protein etc) is their solubilty. Fats are soluble in organic solvents but insoluble in water. 23 Types of Fat Analysis • Extraction Methods Continuous – Goldfinch Semi-Continuous- Soxhlet Discontinuous- Mojonnier • Instrumental Methods Dielectric Infrared Ultrasound 24 Ashes •Ash: total mineral content; inorganic residue remaining after ignition or complete oxidation of organic matter • Minerals: – Macro minerals (>100 mg/day) • Ca, P, Na ,K, Mg, Cl, S – Trace minerals (mg/day) • Fe, I, Zn, Cu, Cr, Mn, Mo, F, Se, Si – Ultra trace minerals • Va, Tn, Ni, Sn, B – Toxic mineral • lead, mercury, cadmium, aluminum 25 Methods for Determining Ash – Dry ashing • high temperature – Wet ashing • oxidizing agent and/or acid – Low-temperature plasma ashing • dry ashing in partial vacuum at low temperature 26 Carbohydrates • Next to water, carbohydrates are the most abundant food component • %carbohydrate=100% - (H 2 O + ash + fat + protein) • Types of carbohydrates include; – monosaccharide: glucose, fructose, galactose – disaccharide: sucrose, lactose, maltose – oligosaccharids: raffinose – polysaccharide: starch, cellulose 27 Methods for Determining Carbohydrate – Chemical reaction • Develop color with chemical solution –HPLC • Determine individual sugar 28 Physical Properties of Foods 29 PHYSICAL PROPERTIES • While chemical properties measures the chemical components of food such as water, protein, fat, carbohydrates, the physical properties determine how the chemical properties and processing ultimately effect the color and texture of foods. 30 Physical Properties • Physical properties include; Color Texture Viscosity (liquids) Texture analysis machines Sensory panels Trained Consumer 31 COLOR • Color can be described in terms of hue, value and chroma; Hue is the aspect of color which we describe by words like green, blue, yellow and red Value or lightness describes the relationship between reflected and absorbed light, without regard to specific wavelength. Chroma describes reflection at a given wavelength and shows how much a color differs from gray. 32 COLOR • More subjective color determination systems include; - Paint color match pages -The Pantone Matching System. - Actual photos of finished food products 33 TEXTURE • The methods of measuring the texture of foods can be roughing divided into those used for liquids (viscosity) versus those used for more solid foods. 34 Fluid Viscosity • Viscosity: a key property of liquids and a measure of the resistance to flow. • More energy required to make a viscous fluid flow than a non-viscous fluid. • The viscosity of a solution increases non-linearly with polymer concentration. • The properties of the solution are conventionally split into three regions: 35 Sensory Properties • Trained Sensory Panels – a few well trained people that characterize flavor, texture and odor versus like/dislike, • Consumer Panels- usually consist of 200 plus people who determine like/dislike, desirability etc. • Additional detailed information on sensory panels can be found in the module “Sensory Evaluation of Foods; 1213” Instruments in Food Analysis Spectrometric Analyses The study how the chemical compound interacts with different wavelenghts in a given region of electromagnetic radiation is called spectroscopy or spectrochemical analysis. The collection of measurements signals (absorbance) of the compound as a function of electromagnetic radiation is called a spectrum. Chromatography Chromatography basically involves the separation of mixtures due to differences in the distribution coefficient of sample components between 2 different phases. One of these phases is a mobile phase and the other is a stationary phase. Kinds of Chromatography 1. Liquid Column Chromatography 2. Gas Liquid Chromatography 40 SUMMARY • This module has presented the topic of Food Analysis by discussing why we analyze food, sampling and preparation, the components of food generally analyzed for (water, protein, fat, carbohydrates) and some general methods of analyzing the physical properties of food (color, viscosity and texture). . 0 17 5 22.0 0.9 66.0 0 20.2 12 .6 1. 0 81. 8 0 16 .4 0.5 1 3 37.0 2.0 25.0 31. 0 5.0 10 -14 58-72 8 -13 2-5 0.5-3.0 78.0 18 .9 2.0 0 .1 1.0 88.6 9 .1 1 .1 0.2 1. 0 94.8. Kinds of Chromatography 1. Liquid Column Chromatography 2. Gas Liquid Chromatography 40 SUMMARY • This module has presented the topic of Food Analysis by