Proximate Analysis

Question 1

What is Food Analysis?

Answer 1

development, application and study of analytical methods for characterizing foods and their constituents

Question 2

What’s the equation for % Moisture?

Answer 2

(wet weight - dry weight) / (wet weight) x 100%

Question 3

What’s the equation for Ether Extract ( % Crude/Estimated Fat)?

Answer 3

(weight of ether extract) / (wet weight of sample) x 100%

Question 4

Is dry weight over or underestimated? Why?

Answer 4

• underestimated
• loss of vitamins and minerals during drying

Question 5

Is Ether Extract ( % Crude/Estimated Fat) over or underestimated? Why?

Answer 5

• overestimated
• other things are dissolved by solvent

Question 6

What’s the equation for % Ash (Mineral Content)?

Answer 6

(weight of ash) / (wet weight of sample) x 100%

Question 7

What’s the equation for % Protein (Nitrogen)?

Answer 7

[ (N in sample)(6.25) / (wet weight of sample) ] x 100%

Question 8

Is % Protein (Nitrogen) over or underestimated? Why?

Answer 8

• overestimated
• assumes all proteins are 16% nitrogen
• there are additional sources of nitrogen

Question 9

What’s the equation for % Crude Fiber?

Answer 9

[(weight of ash + crude fiber) - (weight of ash)] / (wet weight of sample) x 100%

Question 10

What’s Crude Fiber?

Answer 10

• mostly ligand and cellulose (insoluble fibers)

Question 11

Does % Crude Fiber over or underestimate Dietary Fiber?

Answer 11

underestimates

Question 12

What are Soluble Fibers?

Answer 12

• pectins, gums, mucilages
• form a gel in water (dissolve)

Question 13

What are Insoluble Fibers?

Answer 13

• cellulose, lignin, hemicellulose
• remain intact in water (don’t dissolve)

Question 14

What’s Dietary Fiber?

Answer 14

describes all fiber (insoluble and soluble)

Question 15

What’s the equation for % Nitrogen Free Extract (Digestible Carbohydrate Content)?

Answer 15

100% - (% moisture + % crude fat + % ash + % crude protein + % crude fiber)

Question 16

What are the 2 accurate ways to measure fiber?

Answer 16

• Van Soest Method
• Southgate Method

Question 17

What’s the Van Soest Method? What are its strengths?

Answer 17

• method of measuring fiber
• differentiates insoluble from soluble fibers
• determines fermentability
• used for animal feeds

Question 18

What’s the Southgate Method? What are its strengths?

Answer 18

• method of measuring fiber
• provides info on sugars and starches
• provides info on insoluble fibers
• used for human nutrition