Milk Processing

Quality Control

conducted through all steps in milk processing , numerous tests are gathered to analyze presence of microbiological organisms

SPC

specific plate count, total number of bacteria and is used in grading process

PMO

grade A pasteurized milk ordinance, voluntary participated in all 50 states

Grade A

Class 1, 2, or 3

Grade B

class 3

Class one

fluid milk

Class two

cottage cheese, cream, frozen desserts

Class three

butter, cheese

Grade A microbial count

max allowed 100,000 per mL prior to commingling, after may not exceed 300,000 prior to pasteurization

Grade B microbial count

maximum count 1,000,000 per ml prior to commingling, 3,000,000 after

Grade A Somatic cell count (SCC)

not to exceed 750,000 per ml (individual producer)

Handling

within 72 hours after arriving milk must be processed, tested for butterfat and SNF, tested for proper temp, total acidity, flavor, odor, cleanliness, and absence of antibodies

Processing

taken from cow using sanitary milking machine, travels to holding tank (bulk tank), picked up by tank truck and delivered to processing plant, kept in holding tanks, milk separated, pasteurized, pumped through series of pressurized valves to homogenize, cooled less than 42C and then packaged

Seperation

Whole milk is separated into cream and skim milk, centrifuge used cream moves toward center and skim moves outward

Standardization

important to ensure every consumer gets milk with consistent fat content, remixes cream and skim to reach desired for specific designation (product making)

Pasteurizing

heating a liquid to below the boiling point to destroy microorganisms

High temp short time (HTST)

74C for 15 seconds, slightly altered depending on product

ultra high temperature (UHT)

138C for 3 seconds, has a greater shelf life, usually in shelf safe cartons (milk and orange juice)

Homogenization

reduces the milk fat globule size allowing fir even distribution, prevents milk fat separation

Fortification

fluid milk often fortified with vitamins A and D (A reduced during separation, D naturally low), Must be labeled

Shelf life

microbiological stability- growth, biochemical stability- enzymatic or similar changes, Chemical stability- oxidation color changes flavor degradation, physical stability- separation and sedimentation

Shelf life of Pasteurized Milk

8-10 days at 5-7C, can be improved by combining with bactofugation, microfiltration, or high heat treatment

Light effect

losses of tatse and vitamins at 1500 lux