Food Analysis Lecture 2 PDF

Food analysis NUTR 225 3 Credit Hours Dr. Arafat Goja Lect. 2 Introduction to food analysis Objective of food analysis  INTRODUCTION o Food analysis in food science and technology, whether by the food industry, governmental agencies, or universities, often req...

Food analysis NUTR 225 3 Credit Hours Dr. Arafat Goja Lect. 2 Introduction to food analysis Objective of food analysis  INTRODUCTION o Food analysis in food science and technology, whether by the food industry, governmental agencies, or universities, often require determination of food composition and characteristics. o The nature of the sample and the specific reason for the analysis commonly dictate the choice of analytical methods. WHY ANALYZE FOOD?  WHY ANALYZE FOOD? Consumer trends and demands, national and international regulations, and the food industry’s need to manage product quality dictate the need for analysis of food ingredients and products. 1. Nutritional Information: It helps determine the nutrient content (such as proteins, fats, vitamins, and minerals) of food, which is essential for understanding its health benefits and making informed dietary choices. 2. Food safety: It helps identify contaminants like bacteria, pathogens, or harmful chemicals that could pose a health risk to consumers.  WHY ANALYZE FOOD? 3. Government regulations and International Standards and Policies Governments and organizations require food manufacturers to meet certain standards and regulations. Food analysis ensures that products comply with these guidelines, like: (a) Nutrition labeling (b) Standards (c) Food inspection and grading (d) Authenticity  WHY ANALYZE FOOD? 4. Quality control Food analysis ensures that food products meet specific standards for taste, texture, and appearance, ensuring consistency and quality for consumers. 5. Research and development for the development of new products and improving existing products. 6. Sustainability: It can also help in evaluating the environmental impact of food production, guiding decisions toward more sustainable practices.  What properties are mainly analyzed 1- Chemical composition 2- Microbial content 3- Physical properties 4- Sensory properties  References on food analysis techniques Official Methods: are critical in the analysis of foods, to ensure that they meet the legal requirements established by governmental agencies. 1- Association of the Official Analytical Chemists (AOAC) 2- American Oil Chemists Society (AOCS) 3- American Association of Cereal Chemists (AACC) 4- …..etc. Criteria for Selecting Food Analysis Methods  Criteria for Selecting Food Analysis Methods ✓ Making an appropriate choice of analytical technique for a specific application requires a good knowledge of the various techniques. For example, your choice of method to determine the salt content of potato chips would be different if it is for nutrition labeling compared to quality control. ✓ The success of any analytical method relies on the proper selection and preparation of the food sample, carefully performing the analysis, and doing the appropriate calculations and interpretation of the data.  Method selection in food analysis Objective of Characteristics Validity of Consideration assay of methods methods of food composition Applications: Selecting specific method to analyze specific component/characteristic In specific food Criteria & Characteristics for Selecting Food Analysis Methods 1-Safety 2- Simplicity 3- Cost 7- Precision 8- Speed 9- Reproducibility 4- Specificity 5- Sensitivity 6- Accuracy 10- Validation 11- Reliability 12- Official Approval Sampling and samples preparation  Sampling How to measure the quality attributes/ ingredients in food products? “The quality attributes are measured on small portions of food material that are taken from a certain number of small portions taken from a lot”. The process of taking samples from a population is called sampling  Sampling The primary aim and characteristics of sampling: 1- Representative sample 2- Subject to constraints of size 3- Satisfy the sampling plan specifications The sampling plan should be a clearly written with follows: - Number of samples selected - Sample location (s). - Method of collecting samples - Date of sampling  Selection of sampling procedures & analysis ✓ Define the population/lot. ✓ Define Sample: Information obtained from a sample of a particular production lot in a warehouse must be used strictly to make inferences about that particular lot. ✓ Sampling ✓ Sample preparation ✓ Laboratory analysis ✓ Data processing, and interpretation ✓ Results.. Each step of the sampling should represent the precision of the Process and accuracy  Sampling categories ✓ Most sampling is done for a specific purpose, and the purpose may dictate the nature of the sampling approach. ✓ Sampling purposes vary widely among different food industries and the most important categories include the following: 1- Nutritional labeling 2- Detection of contaminants and foreign matter 3- Quality Assurance 4- Acceptance of raw materials, ingredients, or products (Acceptance Sampling) 5- Release of lots of finished product 6- Detection of adulterations 7- Microbiological safety 8- Authenticity of food ingredients, etc.  Factors Affecting the Choice of Sampling Plans 1 2 3 4 Purpose of the Nature of the Nature of the Nature of the inspection population product test method Questions: 1- Is it to accept or reject the lot? 1- Is it homogeneous or heterogeneous? 1- Is the test critical or minor? 1- Is the lot large but uniform? 2- Will someone become sick 2- Is it to measure the average 2- What is the unit size? or die if the population fails 2- Does the lot consist of smaller, quality of the lot? 3- How consistently have past to pass the test? easily identifiable subplots? populations met specifications? 3- Is it to determine the 3- Is the test destructive or 3- What is the distribution of the variability of the product? 4-What is the cost of the material nondestructive? units within the population? being sampled? 4-How much does the test cost to complete?  TYPES OF SAMPLING PLANS Sampling plans are designed for examination of either attributes or variables: 1- Sampling by Attributes: Sampling is performed to decide on the acceptability of a lots/population based on whether the sample possesses a certain characteristic or not. The result has a binary outcome of either conforming or nonconforming. 2- Sampling by Variables: Sampling is performed to estimate quantitatively the amount of a substance (e.g., protein content, moisture content, etc.) or a characteristic (e.g., color) on a continuous scale. The results obtained is compared with an acceptable value and the deviation measured  Acceptance Sampling: Acceptance Sampling: Sampling is a procedure that serves a very specific role: to determine if a shipment of products or ingredients has enough quality to be accepted. Performed by: The food processor before receiving a lot of materials from a supplier or by a buyer who is evaluating the processor’s output Categories for acceptance sampling plane: 1- Single sampling plans. 2- Double sampling plans 3- Multiple sampling plans, ….etc.  Single sampling plans: The decision of accepting or rejecting a lot for this type of plan is based just on one sample of items taken at random. These according to (n, c) plans for a sample size n, where the lot is rejected if there are more than c defective samples Note: If results are inconclusive, a second sample is taken and the decision of accepting or rejecting is made based on the combined outcome of both samples. Double sampling plans: Similar to single sampling plan, but two samples are taken as shown in following (Figure). Double sampling plans: The decision of acceptance or rejection can be made according to diagram presented N= population size; n1 and n2 = sample size; a1 and a2 = acceptance numbers; r1 and r2 = rejection numbers; d1 and d2 = number of non-conformities,  Sampling Procedures: Homogeneous vs. Heterogeneous Populations The location within a population Sampling from such a population is simple, where a sample is taken will affect the as a sample can be taken from any location subsequent data obtained. and the analytical data obtained will be representative of the whole However, Sample preparation can make the sample representative of the population or take heterogeneity into account in some other way.  Sampling Procedures: Manual Sampling: Should take a “random sample” to avoid human bias in the sampling method. air under high pressure to collect multiple 1.5 mL samples. An automatic liquid sampling device that uses The sample must be taken from several locations within the population to ensure it is representative of the whole population. Continuous Sampling is performed mechanically, Continuous sampling should be less prone to human bias than manual sampling  Statistical considerations for sampling: Probability Sampling ✓ The selection of a sample from a population based on chance. ✓ Characterized by elimination of human bias. The most common are: 1- Simple random sampling: This occurs when several units in the population be known, and each unit is assigned an identification number. 2- Systematic sampling: Is used when a complete list of sample units is not available, but when samples are distributed evenly over time or space, such as on a production line.  Statistical considerations for sampling: 3- Stratified sampling: It involves dividing the population (size N) into a certain number of mutually exclusive homogeneous subgroups (size N1, N2, N3, etc.). Stratified sampling is used when subpopulations of similar characteristics can be observed within the whole population. Ex. Tomato juice in different plants.  Statistical considerations for sampling: Nonprobability Sampling ✓ Randomization is always desired. However, it is not always feasible, or even practical, to take samples based on probability methods ✓ Examples: 1- In the preliminary studies to generate hypothesis, in the estimation of the standard deviation so, a more accurate sampling plan can be designed. 2- In certain cases of adulteration such as rodent contamination, the objective of the sampling plan may be to highlight the adulteration rather than collect a representative sample of the population. ✓ The most common are: 1- Judgment sampling 2- Restricted sampling 3- Quota sampling Problems in Sampling ✓ Sampling Bias ✓ Population distribution Errors also may be introduced by not understanding the population distribution and subsequent selection of an inappropriate sampling plan. ✓ Sample storage Samples should be stored in a container that protects the sample from moisture and other environmental factors that may affect the sample (e.g., heat, light, air) ✓ Mislabeling of samples  Statistical considerations for sampling: The reliability of sampling is dependent more on the sample size than on the population size? Factors controlling sample size: Time, cost, sampling methods, and the logistics of sample handling, analysis, and data processing  The effects of samples problem Lack of Poor sample understanding the Mislabeling of Sampling bias population storage and techniques samples distribution Reduced reliability and adequacy of sampling techniques PREPARATION OF SAMPLES  PREPARATION OF SAMPLES Size Reduction ✓If the particle size or mass of the sample is too large for analysis, it must be reduced in bulk or particle size This obtained by dividing sample into quarters. Liquid materials': ✓ Mix, shaking, and homogenized ✓Piped, pumped …etc. Solid sample ✓Grinding ✓Sieving Solid sample ✓Cutting ✓Mincere ✓Blenders  PREPARATION OF SAMPLES Enzymatic Inactivation Food materials often contain enzymes that may degrade the food components being analyzed - The elimination or the controlling of enzymes depend on the nature of the food. - Heat denaturation to inactivate enzymes and freezer storage (−20◦C to −30◦C) for limiting enzyme activity are common methods - Some enzymes are more effectively controlled by changing the pH, or by salting out.  PREPARATION OF SAMPLES Lipid Oxidation Protection ✓ High-fat foods are difficult to grind and may need to be ground while frozen. ✓Unsaturated lipids are sensitive to oxidative degradation and should be protected by storing under nitrogen or vacuum, or by controlling storage conditions. Microbial Growth and Contamination ✓Microorganisms are present in almost all foods and can alter the sample composition. ✓Sample cross-contamination can occur if samples are not handled carefully. ✓Freezing, drying, and chemical preservatives are effective controls and often a combination of these is used.  Preparation of Laboratory Samples ✓ You may have representative samples (sub-samples) from a lot that 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.  Want big impact? USE BIG IMAGE Chairman’s Lorem ipsum dolor et vera Message adipiscing elit. Pellentesque Thank you 4 invax hendrerit diam, et mollis libero. Curabitur sed facilisis elit. UR Coming! 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