Exam One Questions Flashcards
(17 cards)
Define normality.
Normality: the number of mole equivalents per liter of solution
Define titratable acidity.
Titratable acidity: the total amount of acid in a solution or product
Define proximate analysis.
Proximate analysis: analysis for the major compounds in a food: carbohydrates, water, lipids, protein, and ash
Define precision.
Precision: measures how reproducible the values are - how close they are to each other
How do you calculate the % coefficient of variation?
%CV: standard deviation/mean
List three types of food samples you might want to analyze in the laboratory. What are the reasons for analyzing these different types of samples?
Three types of food samples you might want to analyze are the raw ingredients to check for quality, meets specifications, and safety, presence of adulterants, complaint products to determine what was the cause of complaint or what went wrong during processing, and the process control product to check that the process is under control - producing products up to standards.
List at least four things you would need to consider before choosing an analytical technique.
Four things you need to consider before choosing an analytical technique are the cost of the technique, the time required to conduct it, the training required to conduct it, and the tools/equipment/reagents required.
What are the objectives of food analysis?
The objectives of food analysis are to assure a food/ingredient doesn’t have something it shouldn’t, to assure a food/ingredient meets composition requirements, and to determine if a process is under control.
What are the steps of food analysis?
The steps of food analysis are to select/prepare the sample, conduct the assay and calculate and interpret the results.
What are the macro/micro/phytonutrients found in a grapefruit?
Macronutrients: water, carbohydrates (sugar, pectin, cellulose), lipids, proteins (enzymes), and ash
Micronutrients: vitamins (vitamin C, ascorbic acid, acetic acid) and minerals (calcium and potassium)
Phytonutrients: lycopene, liminoids, and bergamottim
What are the metabolites formed from fermentation of pectin in the large intestine?
The metabolites that are formed from pectin in the large intestine are acetic acid, propionic acid, and butyric acid
What is the difference between attribute sampling and variable sampling?
The difference between attribute sampling and variable sampling is that attribute sampling is binary (yes/no) - it determines the presence of a certain characteristic. Variable sampling measures to what extent or how much that characteristic is present.
Describe the steps in determination of % titratable acidity of an unknown sample.
To determine %TA of an unknown sample, you must know the reaction stoichiometry and the normality of the base. You then conduct a titration of the unknown with the strong base. Measuring how much it takes to reach the endpoint of the titration with the help of an indicator and use the following equation (vol. of baseN of baseacid equiv)/vol. of sample
List two reasons why titratable acidity and pH are important to measure in foods and beverages.
pH is important for determining microbial growth and TA is important for taste and is a quality indicator in wine
How do you find the moisture content on a dry and wet basis?
MCWB: (Wi-Wf)/Wi
MCDB: (Wi-Wf)/Wf
Where are acetic acid, lactic acid, malic acid, and tartaric acid commonly found?
Acetic: vinegar
Lactic: yogurt/dairy
Malic: apples
Tartaric: grapes
What are some sample preparation considerations?
Some sample preparation considerations are enzyme inactivation, lipid oxidation, and microbial growth.
