Raw material specification, Lecture notes of Food Science and Technology

Download Raw material specification and more Lecture notes Food Science and Technology in PDF only on Docsity!

I N T R O D U C T I O N T O

F O O D P R O C E S S I N G A N D

P R E S E RVAT I O N ( 2

n d

L e c t u r e )

BS 2nd year (3rd semester)

Presented by;

Miss Kulsoom

LEARNING OBJECTIVES To have keen knowledge about Food Processing & Preservation Raw material specifications Deterioration and damage to raw materials

Deterioration of Raw Materials All raw materials deteriorate following harvest, by some of the following mechanisms:

Endogenous enzymes:

Postharvest senescence and spoilage of fruit and vegetables occurs through a number of enzymes mechanisms, including oxidation of phenolic substances in plant tissues by phenolase (leading to browning); sugar–starch conversion by amylases; postharvest de- methylation of pectic substances in fruits and vegetables leading to softening tissues during ripening and firming of plant tissues during processing.

Chemical changes:

These include deterioration in sensory quality by lipid oxidation; non-enzymic browning; and breakdown of pigments such as chlorophyll, anthocyanins, and carotenoids. Nutritional changes: Breakdown of ascorbic acid is an important example. Physical changes: These include dehydration and moisture absorption. Biological changes: Examples are the germination of seeds and sprouting. Microbiological contamination: Both the organisms themselves and their toxic products lead to deterioration of quality, as well as posing safety problems.

Difference b/w deterioration and damage…?

Damage of raw material arise through external or internal forces while deterioration is about post harvest changes and other changes

Thanks

For your kind attention