Food Analysis Project NDFS 350 March, 21, 2014 Ya Ya Wong. I. Yogurt

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1 Food Analysis Project NDFS 350 March, 21, 2014 Ya Ya Wong I. Yogurt II. Product Description and Summary of Standards of Identity Basic strawberry yogurt with little pieces of strawberries inside. According to Code of Federal Regulations Title 21, yogurt is the food produced by culturing one or more of the optional dairy ingredients (which are cream, milk, partially skimmed milk, or skim milk, used alone or in combination) with a characterizing bacterial culture that contains the lactic acid-producing bacteria, Lactobacillus bulgaricus and Streptococcus thermophilus. One of more of the other optional ingredient s(b) (d) may also be added. In addition, yogurt must contains no less than 3.25% milkfat and no less than 8.25% milk solids not fat, and has a titratable acidity of no less than 0.9%, expressed as lactic acid before the addition of bulky flavors. The food may be homogenized and shall be pasteurized or ultra-pasteurized prior to the addition of the bacterial culture. Flavoring ingredients may be added before or after pasteurization. For the purpose of extending shelf life, yogurt may be heat treated again after culturing is completed. There are other specifications in regard to optional vitamin addition, other optional ingredients, nutritive carbohydrate sweeteners, flavoring ingredients, color additives, and stabilizers. III. Nutritional Composition Table 1: Approximate amounts of nutrients per serving of yogurt (serving size 1 cup = 150g)* amount percentage Calories 80 cal - Calories From Fat 0 cal - Total Fat 0 g 0% Saturated Fat 0 g 0% Trans Fat 0 g 0% Cholesterol <5 mg 1% Sodium 75 mg 3% Potassium 240 mg 7% Total Carbohydrate 15 g 5% Dietary Fiber 0 g 0% Sugars 10 g - Vitamin A - 15% Vitamin C - 0% Calcium - 15% Iron - 0% *Dannon Light & Fit single serve 6-Oz. cup of strawberry yogurt

2 Table 2: Tests for measuring each of the nutrients required for nutritional labeling Nutrients Test Actual Method in Industry* Saturated Fat AOAC international 2005 Offical Method Fat (Total, Saturated, and Unsaturated) in Foods. Gas Chromatography See also AOAC 2005 Offical Method Fat in Foods. Chloroform-Methanol Extraction Method Trans Fat Soxhlet Method and Gas Chromatography Cholesterol AOAC international 2005 Offical Method Cholesterol in Foods Direct Saponification Gas Chromatographic Method Sodium Potassium Total Carbohydrate Dietary Fiber AOAC international 2005 Official Method Sodium in Fruits and Fruit Products. Flame Spectrophotometric Method Flame AES By difference AOAC international 2005 Official Method Total Dietary Fiber in Foods. Enzymatic Gravimetric Method Sugars AOAC international 2005 Official Method 925 Vitamin A AOAC international 2005 Official Method Determination of Vitamin A (Retinol) in Foods. Saponification, extraction with organic solvents, then normal phase HPLC with UV detection Liquid Chromatography Vitamin C Microfluorometeric Method Calcium Bioassay Iron AOAC international 2005 Official Method Atomic Absorption Method ICP-AES Data bases are utilized that provide the proper nutritional claims. IV. Raw Ingredients A. List of Raw Ingredients - List the raw ingredients used in your product. -Non Fat Milk -Modified food starch -Kosher Gelatin -Vitamin A -Water -strawberries -Fructose -modified corn starch -natural and artificial flavors -aspartame

3 -Malic acid -Potassium Sorbate -Sodium Citrate -Acesulfame Potassium -Sucralose -Yogurt cultures including L. Acidophilus B. Tests on Raw Ingredients 1. Milk Fat Solid in Milk a. Specific Name of Test: Near IR or Babcock b. References: i. Near IR: Joseph Love from Smith, private conversation. ii. Babcock milk fast test: AOAC 1980, ; Joseph Love from Smith, private conversation. iii. Roese-Gottlieb Method: AOAC 1980, ; online research CFR c. Purpose for Measuring: To determine the milk fat content so that it is of the standard of identity that the milk contains no less than 3.25 percent milk fat. d. Choice of Method: Near IR or the Babcock Method are more commonly used in industry instead of the Roese-Gottlieb Method, the official method (AOAC 1985, , CFR of the United States of America, online research.) By using the near infrared is fast and give finished butterfat and total solids. The reason why the calibration method most commonly used is the Babcock milkfat test rather than the Roese-Gottlieb method is not sure. Compared to Babcock method Gerber Method is actually simpler and faster, and there is a wider application of dairy products isoamyl alcohol prevents charring of sugar that occurs with Babcock method. However when using the Babcock method, sample do not need to be dried beforehand. e. Principle: i. Near IR: Fat is extracted from a homogeneous sample by a chloroformmethanol solvent containing an internal standard, and then is analyzed by infrared spectrometry. By the ratio of the areas of the bands fat content determined. ii. Babcock milk fat test: everything in milk except fat dissolves in sulfuric acid. iii. Roese-Gottlieb Method: using ammonia to break down any lipo protein bonds in milk allowing all the fat to then be dissolved by ether and after separating the organic layer. Then extracts are dried, weighed. f. Procedure: i. Near IR: After fat is extracted by a chloroform-methanol solvent, different ratio of the internal standard is added. The internal standard found using is a low viscosity apolar methylsilicone oil (MS 550). Two bands should be found on the infrared spectrum (5.72 µm and 7.88 µm). Fat content is determined by calculating the ratio of area under curves. ii. Babcock milk fat test: add concentrated sulfuric acid to milk sample. After centrifugation to ensure complete separation with no bubbles in the fat, fat content is measured.

4 iii. Roese-Gottlieb Method: After couple times of extraction by adding NH4OH, alcohol, ether and followed by shaking sample vigorously and cool it. The extracts are evaporated, dried in oven or vacuum oven, and weighed. 2. Milk Solid non from milk fat a. Specific Name of Test: i. Solids in Milk Enzymatic Method ii. Moisture analyzer b. References: i. Solids in Milk Enzymatic Method: AOAC 1980, ; online research CFR ii. Moisture analyzer: Joseph Love from Smith s, private conversation. c. Purpose for Measuring: To determine the lactose content in milk. d. Choice of Method: The latter method takes a lot less time (few minutes) compared to the first method. (Joseph Love from Smith s, private conversation) e. Principle: i. Lactose in Milk Enzymatic Method: After drying weight the residue and report as % total solids. ii. Moisture analyzer: moisture analyzer that uses a heating element in a scale and measures the remaining weight of the mix at the end of product sample heating f. Procedure: i. Lactose in Milk Enzymatic Method: Heat sample on steam bath and exposing maximum surface of dish bottom to live steam. Then sample is put in the air oven for couple hours. Weight the residue and calculate total solids. ii. Moisture analyzer: place sample on a moisture pan with the filter pad on the top. Then place it in the moisture analyzers.

5 Set yoghurt V. Processing of Product A. Schematic Diagram of Processing Steps Raw milk Quality test on raw milk Basic Yogurt Processing Standardisation of Milk tests on milk addition of stabilizers (pectin) Homogenization After cooling, add starter culture, flavoring and other ingredients Pasteurization Packing Incubation ph is measured Stirred yoghurt Incubation Cooling Cooling Stirring Cooling, pumping, and packaging Quality Tests To Market!

6 B. Description of Processing Steps - Briefly explain the steps in the processing diagram given in part A above. Milk Standardization is where milk is mixed with skim milk and cream to standardize or adjust the fat content to the desired level. Depending on the types of yogurt (skim milk yogurt to normal yogurt ) they are of different fat content. Stabilizers such as pectin are often added here as well to enhance the desired mouth feel, appearance, viscosity and to prevent whey separation. However it is noted that the use of stabilizers is not allowed for plain yogurt. Homogenization of the milk base is an important processing step for yogurts containing fat. It helps making milk fat globules into smaller globules. This prevents creaming (separation of fat) during fermentation or storage. It also increases whiteness and enhances consistency of yogurts. Heat Treatment of milk in yogurt processing is prior to culture addition. Usually batch pasteurization is used (85*C for 30 min or 90-95*C for 5 min). This kills unwanted microorganisms, which provides less competition for the starter culture. It also removes dissolved oxygen assisting starter growth. Fermentation process happens after the milk is being cooled down and starter cultures are added. In this case L. Acidophilus is used as starter cultures. Bacterial fermentation converts lactose into lactic acid, which reduces the ph of milk. Cooling of yogurt is allowed happens before the adding of fruit and flavoring ingredients. It is usually blast chilled to <10*C and stored to reduce further acid development. In the production of set yogurt, yogurts are directly transferred to a cold store or blast chilled in cooling tunnels. For stirred yogurts, cooling is first performed by agitation in the jacketed fermentation vat and the product is sheared and smoothened by devices like back-pressure values, high shear devices or sieves. Quality assurance tests are run before transporting product into market. C. Tests During Processing - Describe the tests required during processing using the format below (as described above in Section IV.B.1.a-f).. Note that quality control tests on the final product are described in Section VI. 1. ph value a. Specific Name of Test: ph meter b. References: i. ph meter: Joseph Love from Smith s, private conversation c. Purpose for Measuring: To ensure the yogurt is property fermented and to prevent over fermentation. d. Choice of Method: It is fast and easy. e. Principle: i. ph meter: By measuring voltage difference between the reference electrode and indicator electrode, concentration of hydronium ion can be calculated by using the Nernst equation and the activity equation. f. Procedure: i. ph meter: calibrate the ph meter with different buffer solutions, then used to meter ph of sample solution. VI. Tests on Final product A. Tests Required for Quality Control There may be tests that need to be conducted on your finished product to conform to the standard of identity or to ensure uniform quality and safety. Give

7 tests that are routinely required as well as those that need to be done less frequently. Some of the nutrients required for standard nutritional labeling or additional labeling information may need to be analyzed more often by a faster method for quality control purposes. Include a description of the appropriate methods for these faster analyses. 1. Viscosity a. Specific Name of Test: using Brookfield viscometer b. Reference: (Joseph Love from Smith s, private conversation) c. Purpose of Measuring: Viscosity is crucial aspects of the quality and overall sensory consumer acceptance of yogurts. d. Choice of Method: It s fast and easy. e. Principle: it uses the principle of rotational viscometry the torque required to turn a spindle in a fluid to measure the viscosity of the fluid. f. Procedure: put sample in the viscometer and obtain measurement. 2. Titratable acidity a. Specific Name of Test: ph meter b. References: i. Titrimetric Method: AOAC 1980, ; online research CFR ii. ph meter: Joseph Love from Smith s, private conversation c. Purpose for Measuring: To meet the standard of identity of no less than 0.9% of titratable acidity. d. Choice of Method: The Titratable acidity test is based on the printed Official Final Action. However, usually industry use ph meter to test ph more often than Titratable acidity due to time and easiness. e. Principle: i. Titrimetric Method: using phthln as indicator, by titrating sample with known amount of NaOH sample would have a persisting pink color. Concentration of lactic acid in the sample can be calculated by using the amount of NaOH used to get the end point. ii. ph meter: By measuring voltage difference between the reference electrode and indicator electrode, concentration of hydronium ion can be calculated by using the Nernst equation and the activity equation. f. Procedure: i. Titrimetric Method: titrate sample with phthln added with a known normality of NaOH. Concentration of lactic acid can then be calculated. ii. ph meter: calibrate the ph meter with different buffer solutions, then used to meter ph of sample solution. B. Tests Required for Additional Labeling Information There may be nutrients or other chemicals in your product which are not included in standard nutritional labeling requirements but could be required or are reasonable to give on the label of your products. (e.g. nitrates, the B vitamins, vitamin D). Describe the appropriate rapid and/or official method of analysis for such nutrients. There is none found from contacts.

8 VII.References AOAC, Section 16, Washington D.C. AOAC international, Section 16, Washington D.C. Anonymous Code of Federal Regulations. Title 21 (or 9). Office of the Federal Register, Washington, D.C. Lee WJ, Lucey JA Formation and Physical Properties of Yogurt. AAAP 23(9):

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