FST 140: Factors affecting Duration of Thermal Process

Nature of Food

• low acid food

• Medium

• Acid food

• High acid food

Low-acid food

pH 5.0 and higher

Medium

pH 5.0 - 4.5

Acid foods

pH 4.5 to 3.7

High acid foods

pH 3.7 and lower

Redox potential (Eh)

• easy by which a substrate gains or lose electrons

Oxidized Environment

produces aerobic conditions

Reduced Environments

creates anaerobic conditions

Storage Temperature

higher storage temperatures accelerate microbial growth

Danger Zone

• temperatures between 40F - 140F allow rapid growth of bacteria, yeast and molds

Conduction heating

• in solid foods, relatively slow transfer of heat

Convection heating

in fluid foods, relatively faster rate of heating compared to solid foods

Mixed heating

in foods such as changes in viscosity during the process

Microbial load

the higher the initial microbial load, the longer required processing time

Size and type of can

• container is an essential factor in the preservation of foods by canningHe

Hermetically sealed containers

container designed and intended to be secure against the entry of mcgs to maintain the commercial sterility of its content after processing

type L plate

used for strongly corrosive products

type MR plate

used for mildly corrosive foods

type MC plate

used for foods with little corrosion

Oleoresinous

these enamels have good barrier resistance between acid foods and the metal of the can

R - enamel

to protect the natural pigment of highly colored foods such as fruits

C - enamel

this offers sulfur resistance to prevent black sulfide discoloration in foods

Phenolics

enamels have greater impermeability and chemical resistance than oleoresinous types

Epoxy

characterized by heat stability and excellent stability

Vinyl

used for double coating in combination with oleoresinous or phenolic enamel

Can size

determined by a code or a can number